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    SUMMARY ?ELECTRIC POWER TRANSMISSION? Improved management of an electrical power transmission network is achieved by providing at each of the subscriber premises a load control device which includes a power correction system to apply a capacitive load and/or a switched reactor to voltage correction through the input voltage and a pickup system defined by a pair of meters one in the supply and the second one downstream of the voltage correction to detect variations in the power factor. A control system operates to control the power correction system in response to variations detected by the pickup system and to communicate between the load control device and the grid control system so as to provide a bidirectional interactive system.
    公开号:BR112017008064B1
    申请号:R112017008064-8
    申请日:2015-10-22
    公开日:2022-02-01
    发明作者:Glenn Kenton Rosendahl
    申请人:Glenn Kenton Rosendahl；
    IPC主号:
    专利说明:

    [001] This invention relates to an electrical power transmission network designed to compensate for the power factor which arises due to reactive loads in the network and to a load control device to be used at subscriber premises. on the network. BACKGROUND OF THE INVENTION
    [002] The most challenging problems that electrical systems face today are; power factor control, transformer load unbalance and non-linear loads, in addition to transformer unbalance and injection of disruptive harmonic currents into the system. All these problems erode the efficiency and stability of the electrical system, in some cases more than 40% of energy is lost en route to the customer.
    [003] Electrical system compensation is currently top-down, high-voltage and high-energy correction equipment is installed at secondary distribution stations. This can include static or switched capacitor banks and/or switched reactors for power factor or voltage correction, universal power flow controllers to balance loads and control bus voltages. These devices can address some of the challenges, but the costs are significant and the solutions are suboptimal. They require a large investment in engineering, made-to-order equipment, infrastructure to assemble equipment, have a low fault tolerance and require maintenance. SUMMARY OF THE INVENTION
    [004] In accordance with the invention there is provided a load control device for use in an electrical power transmission network including a plurality of subscriber dependencies for receiving electrical power, each including a plurality of user devices in a power supply circuit, at least some of which cause power factor variations when operated, and transmission lines supplying electrical power with each of the subscriber dependencies having a drop from one of the transmission lines to an input of power supply, the load control device being arranged for connection to a respective one of the power supply inputs to control the power supplied from the power supply input to the user devices in the power supply circuit. food,
    [005] the load control device comprising:
    [006] a detection system to detect variations in power factor caused by user devices;
    [007] a power correction system to apply a capacitive load to the power supplied by the outage at subscriber premises;
    [008] and a control system to control the power correction system in response to detected variations.
    [009] Preferably the detection system comprises a meter generating data related to the true standard RMS values of voltage, current and Real Power. These values can then be used by the control system to calculate the power factor to generate a value of a required capacitive load to improve the power factor.
    [010] The power factor may where possible be optimized to the maximum unity power factor so that only real power is flowing in the system. However, in some cases it is necessary to apply a load which provides an improvement without reaching the theoretically ideal situation. Either the system is at full compensation or the system is configured to improve transformer unbalance.
    [011] Transformer unbalance is a result of asymmetrical loading of each phase of a typical three-phase system. By compensating the capacitive load of each phase independently, improvements in transformer unbalance can be made. Although a less than ideal solution for both power factor and load unbalance will result when using only capacitor compensation the overall operating efficiency may be a better solution given the resources available. The present invention in its simplest form is passive capacitive compensation for one phase only. More load imbalance control can be done with the addition of reactive compensation components and multiphase implementation of the control, where current imbalances can be redirected within the control to balance phase currents. These improvements come at a price in complexity and cost. The addition of distributed solar/wind generation can help with unbalance issues by giving this power to heavily loaded phases.
    [012] In some cases the system can be used to correct the power supply waveform to remove distortion caused by noise, improving power quality. Such noise can arise from many different user devices which do not provide linear power usage. In order to correct for noise and thereby better balance the power supply waveform, the detection system generates data related to FFT spectra of the power supply waveform. The control system then uses the data from the FFT analysis to provide a correction signal at a rate significantly greater than the frequency of the power supply waveform. That is, the detection system can be used from this analysis to generate data reporting Total Harmonic Distortion (THD).
    [013] A reference current waveform is in phase with the voltage waveform and is sinusoidal. The error signal is developed from the results from the load current FFT spectra. The fundamental current frequency components are removed as no compensation is required. All other frequency components reduce the power quality and constitute the error signal. The reference signal minus the error signal provides correction pulses for an Active Power Factor Control (APFC). APFC shapes the shape of incoming current in sine waves by removing power noise and improving power quality.
    [014] The APFC produces a direct current to charge a local capacitor to a high voltage. This energy can be re-inverted back into the system using a power inverter, bled, or it can be another source of energy for local solar/wind generation systems. It should be mentioned that this system does not affect the power quality within the premises. Power quality is improved as viewed from the system side and limits the effect of noise on nearby premises. The present invention can be used to reduce noise from problematic loads within a facility, such as variable speed drives in industrial contexts. Where control is installed to monitor and compensate for a specific load or group of loads.
    [015] Preferably the detection system comprises a first meter generating data on the fall and a second meter generating data downstream of the power correction system. Both meters provide the same parameters taken from the power supply so that the data can be compared. For example, the control system can be used to compare data emitted from the second meter with data emitted from the first meter to determine a level of improvement in power factor achieved by the power correction system. This comparison provides an autonomous computing function where the level of ongoing improvement in power factor can be monitored. This value can be used if required in a calculation of a refund to the customer for that upgrade and can be used to monitor a set of dependencies on a particular transmission line where and how improvements are being made at the dependency level which may be compared with improvements detected at the macro level in the relevant transformer. That is, the load control device is arranged to communicate using the upgrade related communication system data to the network control system. Furthermore, the load control device can be arranged to communicate data related to Actual Power to the network control system. This provides data to the network management system of system operation and dependencies allowing better control of the network at the supply end.
    [016] Typically the power correction system comprises static or switched capacitor banks. These banks can be switched on and off as required by the control system to provide a capacitive load value to manage the power factor. For example, a binary system can be employed using n number of capacitors each having twice the value of the previous one to provide up to 2An different values for rigorous management of the capacitive load. Finer control of the power factor can be achieved with a reactor switched in parallel with the capacitor bank. By adjusting the firing angle on the reactor, infinite current resolution can be achieved from its maximum current rating to zero. This enables the system to track the power factor very accurately.
    [017] In addition to the capacitive load control, it is also possible in some cases to provide an Active Power Factor Control (APFC) in the power correction system. This is a known arrangement that can be switched at high rate to filter out noise and Total Harmonic Distortion detected by FFT analysis. The switch, which can be operated at a high rate of multiple times per cycle, connects and disconnects an inductor from the circuit, which therefore changes the input current consumption in a way that smoothes the effects generated by noise from user devices. The switch is thus operated in response to the error signal derived from the FFT analysis of the power supply waveform for current correction. This system consumes energy from the system, which can be bled with a resistor, be another source of energy for local solar/wind generation, or be the source for a local power inverter. Ideally this should be coupled with a local solar/wind generator as these systems already have an integrated power inverter saving installation costs. Wasting this energy through a bleed-in resistor is only convenient if the losses are minimal and does not justify the additional costs of a power inverter.
    [018] In addition, the load control device may include a system for disconnecting from the power supply circuit within the user's premises certain devices determined among the user devices for load shedding. This is typically accomplished by a switch on one or more of the circuit's drop wires to disconnect high load items such as heating and cooling systems.
    [019] The control system can also be programmable to change the response to variations detected by the detection system. That is, the control system can use adaptive intelligence to change the emission that controls the power correction system in response to detected variations depending on different circumstances. Such an emission change could use time of day or input voltage or power factor as parameters in the schedule. The system operates to maintain a power factor or voltage at a point or a weighted combination of several parameters to meet a required condition.
    [020] In addition, the control system can be programmable by data received by the communication system from the network control system. That is, the network control system can communicate to the individual control systems of the load control device instructions which depend on the state of the network as detected at the edge end of the network. This instruction may be to control the components, particularly the power correction system, in a different way than would be used by the system in the absence of information from the mains control. In this way voltages and load shedding can be centrally controlled by instructions from the network. Thus an interactive communication system can be configured where the communication system operates bidirectionally to supply information to the network control system and to receive instructions obtained from the network either as a result of that information or from other data. conventionally obtained from the network.
    [021] Typically the communication protocol is not configured to require high-speed communication of complex real-time instructions for the multiplicity of subscriber dependencies, but instead the system will typically be adaptive to generate programming over time. which changes in response to detected data. In this way, the central network control can communicate programs to the load control devices over time which are deployed on a real-time basis depending on locally sensed data. However, high-speed communication techniques can be used to manage the system in real time. The communication system can be configured to periodically provide a synchronization pulse to controls in the field. This enables the system to take a global snapshot of measurements across the system enabling better power tracking and access to system stability.
    [022] As is well known, the voltage on the transmission line can vary depending on the distance from the tip end and it is also known that the voltage can be managed by reactive loads, particularly capacitive loads applied to the transmission line in various positions along the line. Using this knowledge, the control system in all or some of the individual premises can be operated to change the voltage at the respective drop-off in response to data provided by or communicated by the grid control system. That is, the local control system can be used to add capacitive load or to drop loads in response to data from the grid control system. In this way, network instability can be detected early by data from the local load control devices and can be better managed by operating the local load control devices to take steps to alleviate stability problems. For example, a voltage profile along the transmission line can be managed in this way. The network control system can arrange individual dependency control systems to react to events in the system in order to maintain stability. Much like autopilot setting the voltage and switching loads on or off to keep the voltage measurement constant. This method has the net effect of leveling the voltage grading along a transmission line so that the voltage drop across the line as a whole is reduced.
    [023] Electrical systems are beginning to employ variable voltage transformers to manage overall system power utilization during peak periods. By lowering the system voltage, loads draw less current which means less energy is delivered overall, making the most of available resources. Variable voltage transformer efficiencies are increased by the ability of the present document layout to minimize the drop of a distribution line as a whole, thereby allowing for greater voltage drops while still maintaining rated voltage tolerances within each of the dependencies.
    [024] The grid in the present document can also be used to control a power supply system, such as solar energy stored in battery banks, at subscriber premises to add power to power at the premises. That is, the control system can be arranged to control the capacitor banks, any load shedding, and any energy added by the power supply system in response to detected variations. Local variations can be used in conjunction with data communicated from the network control system to control these components to better manage the network.
    [025] According to a second aspect of the invention there is provided a load control device for use in individual subscriber dependencies of an electrical power transmission network comprising a plurality of subscriber dependencies for receiving electrical power, each including a plurality of user devices in a power supply circuit, at least some of which cause power factor variations when operated; transmission lines supplying electrical power; and a network control system for controlling power supply on transmission lines where each of the subscriber dependencies has a drop from one of the transmission lines to a power supply input;
    [026] the load control device being arranged for connection to a respective one of the power supply inputs to control the power supplied from the power supply input to the user devices in the power supply circuit,
    [027] the load control device comprising:
    [028] a detection system to detect variations in power factor caused by user devices;
    [029] a power correction system to apply a capacitive load to the power supplied by the drop to subscriber premises;
    [030] a control system to control the power correction system in response to detected variations;
    [031] and a communication system to make the communication between the load control device and the network control system.
    [032] The load control device may be arranged to provide any one or more of the network features mentioned above.
    [033] The arrangement as described in this document therefore uses a bottom-up approach to electrical system compensation and monitoring. Instead of one large installation, many thousands of small units are distributed across a system, ideally across individual power services or loads. Point of Load Compensation (PLC) is the ideal setting to minimize losses and maximize system stability. Several design factors contribute to significantly reducing costs when compared to top-down solutions.
    [034] Designing compensation equipment for the low voltage side reduces component costs, increases component reliability and availability. Installation costs are minimal using well-established models from the telecommunications industry.
    [035] Typical substation to load distances are many kilometers and top-down compensation has limited effect on these transmission lines. Installing compensation closer to the loads and finer compensation resolution further reduce losses and increase system stability and flexibility.
    [036] The positioning of these devices at the load point gives rise to a natural communication network, the electrical system voltages, currents, and the phase vectors themselves. A global communication network is provided for system control and synchronization as a whole. But in the absence of global communication, individual units operate as a kind of reflective control, monitoring electrical system line values and reacting to changes with better operating practices. By providing a much faster response to disturbances than a traditional system, both system stability and availability are increased. This network of monitors and energy compensators generates a unique perception of the functioning of each installation. Using this information, self-organizing and learning algorithms extract operating best practices for each individual system. This information can assist in almost every aspect of electrical system management including energy theft. Current trends are leading to a distributed generation model with the advent of small-scale solar and wind generation. The distributed generation model presents many challenges for current supervision control and Data Acquisition (SCADA) systems, based on a centralized control ideology. The present unit can easily integrate the distributed generation model into the system and use them as active elements in power generation, system control and compensation.
    [037] One form of the present invention includes two measuring points: one on the system side and one on the load side. Power compensation modules are installed between these two meter points. This unique scheme allows compensation effects to be measured and quantified, and forms the basis for performance contract computation. Meter emissions from the load side (and/or system side) can be used as feedback by active compensation modules. This allows modules to cancel out or reduce noise generated from SMPS, CFL, problematic LED lighting and similar non-linear loads. Emissions from the meter on the system side show the results of such efforts. Each measurement point can measure the true standard RMS values of Voltage, Current, Actual Power, as well as precisely determine power factor, FFT spectra, Total Harmonic Distortion (THD) and many more. These meters are field-upgradable and under software control so that they can be programmed, tuned or focused on important aspects of the data to aid in control or monitoring tasks.
    [038] Dual meter structure enables compensation of visible loads and conditions avoiding any opportunity for overcompensation. And so any possibility of instability created by the device's compensation actions. The device is inherently stable by design and can only provide compensation or actions that will improve system stability. All this is done without the need for communication with any other device, control of electrical network, etc. This has a profound effect on network security. Hence the interruption of the electrical network by command of these (potentially millions of) devices to do damage to the system is impossible.
    [039] Using a current inverter as the compensation element significantly improves the flexibility and stability of the present invention. A current inverter measures the injected current and the system voltage as feedback to control the amount of injected current and the position of that current with respect to the system voltage. With the current inverter or Universal Compensator any passive element or combination of (capacitor, resistor, inductor and negative resistor) can be implemented with software using this framework. The current injection feedback control avoids any resonant interaction with external system components highlighting its inherent stable characteristic. Structures are constructed from half-bridges which interface direct current link bus(s) with alternating current systems or renewable energy sources. Current inverters can be constructed with half-bridges to interface with any number of alternating current phases or renewable energy sources (as shown in Figure 5). At a minimum, only one half-bridge is required to interface a renewable energy source such as solar, wind, or battery with a DC link bus. This structure has a natural modular design topology, where additions to the compensator can be made as needed. Multiple half-bridges can be mounted in parallel to maintain an AC phase or power source to increase current transfer capability and reduce operating noise through interleaving techniques.
    [040] Current Injection Compensation uses a two meter structure with the compensation injected between these two meter points. When power flows from the system to the service side the compensating action is determined by the service meter. The injection of correction currents enables the entire service side to appear from the systems side as a resistive load (PF=1). The power factor and harmonic content cleanup correction has a great benefit to the system. The margin of stability is significantly increased and systems with older relay equipment benefit from the removal of undetectable harmonics. As local renewable energy sources are added to the service side, power will flow to both the system and service loads. With the present two meter structure and injecting renewable energy once again between these two meter points the flow of this energy can be measured and conditioned using the current injection inverter used for compensation.
    [041] The system acts as a universal compensator where the dual meter structure is particularly useful in this instance to enable reverse power flow. Connect a renewable source such as solar panels, wind generators, and batteries at the offset point between the two meter structure using a generic half-bridge. This enables the inverter not only to compensate for VARs, but to inject real power from these renewable sources and add the required VAR compensation for these sources before they are injected into the system. The dual meter enables tracking of that Real Power, the amount and where it is delivered, whether to the system, service or both. This is an important distinction from current available systems where delivered energy is metered, but without VAR tracking and compensation. And if VAR compensation is provided, a communication network is required to provide Power and VAR orders. However, in the present invention communication is not required for the device to provide VAR compensation and maintain system stability.
    [042] The inverter can be configured as a single-phase, two-phase, three-phase delta- or Y-connected inverter, or almost any polyphase arrangement can be accommodated. If more than one phase is compensated, the inverter can also balance the phase currents as part of the compensation, without external communication. The net effect of a multiphase compensator is that power is balanced with a power factor of unity and harmonics are erased from the system. This load is now seen from the distribution transformer as an ideal balanced resistive load.
    [043] The system provides distributed compensation since SMPS and CFL devices, especially low-voltage ones, tend by design to concentrate the current drawn on voltage spikes. The peak current point is very narrow and large in magnitude, looking like a function of impulse. This creates a large number of high current harmonics injected into the system. In addition, multiple devices work to increase this peak amplitude regardless of manufacturer and it is an industry design practice for minimal cost. These types of loads can saturate compensation devices. The distributed compensation described in this document enables multiple units in the wiring path to assist in compensating these loads.
    [044] Therefore, some fixed devices may require more compensation than is available at the point of load. Now all devices on a wiring path can contribute to this compensation.
    [045] Distributed compensation for VARs, Harmonic Distortion, Real Power, if a renewable energy source is locally available, can take the form of devices installed along wiring paths to compensate for physically connected and renewable loads attached to these devices. Compensators built into outlets can replace standard outlets with added features for load shedding and demand-side management of fixed loads. Communications between these devices enable blackout management and recovery where priority loads are restored first and as more power sources become available more loads are restored. Priorities can be rigidly set, by location, or digital ID tags attached to pluggable loads such as refrigerators to set priority wherever they are plugged in. Communication is not strictly necessary to perform compensation functions, but is required to implement prioritized load restoration.
    [046] The arrangement revealed in this document provides the following unique features and advantages: 1) Dual meter structure: allows energy flow reversal and computation. 2) Distributed offset placement improves overall performance and efficiency. 3) Can be used to remove the need for a set of PFC circuits to be included within consumer devices, saving manufacturing costs, the environment, time to market, and the consumer. Power grid infrastructures are expected to last decades, perhaps centuries. Whereas consumer products have an average life of 3 to 5 years. If the current device circuitry is built into the electrical network it becomes adaptable and more resilient, reducing or eliminating the need for such circuitry to be included within consumer devices. This action can have a huge impact on society and the environment. 4) Enables delivery of more useful energy through individual circuit breaker circuits without tripping circuit breakers or violating electrical codes. This can be very significant in older neighborhoods where an electrical distribution network has lower capacity. Typical homes in these neighborhoods have service sizes in the range of 40 to 80 A. This may not be enough current to run modern appliances such as air conditioners which have low power factors. Employing the present compensation methods another 20 to 30% of power would become available to help satisfy these added loads. This can be achieved without adversely affecting the local distribution network, but actually improving its operation, stability, and maximizing power sales to the supplier.
    [047] The arrangement in this document can take many forms including a panel at the service entrance, as described in detail below. However, it can also be supplied as a black box along the individual wiring paths. In this way it can be used to replace outlets or can be molded into electrical cables.
    [048] The provision in this document can be used with a system for dual-phase services. In this case, the outputs along the wiring paths with both phases can now select which phase will be used to originate loads in order to improve the phase balance in a natural and transparent way.
    [049] Furthermore, if an SMPS load is identified as the load and can operate more efficiently at 240V and not at 120V it can be sourced at 240V once again in a natural and transparent way. Most Voltage adapters available today are of universal voltage construction which can be sourced from 90 to 260 Volts of alternating current and compatible with world markets. The downside is that the lower the source voltage, the lower the overall efficiency of the adapter. Hence, this new adaptation would allow these loads to operate at the design's peak efficiency even in 120 Volt alternating current environments.
    [050] One of the biggest problems facing electrical systems today is how to accommodate a large number of renewable energy sources distributed close to load centers. In some areas these distributed sources are larger than the grid connection of electrical systems. The problem arises when the system experiences a power cut. How to restore literally thousands of generators (distributed renewable energy sources) and thousands of loads in an orderly and stable way Traditionally, the grid connection is the strongest or only source after a power outage. The system restarts, but must start under the load of any load that was present before the power cut. This can result in a significant payload size. One of which in the near future will be beyond the capacity of grid connections and in that situation current methods will not work. A solution using the present invention is possible. Upon detection of grid instability and opening of the input supply switch 17, the local system can be isolated from the grid. Using available renewable energy sources and removing any non-priority loads this isolated system can continue to operate. After the grid bond connection is re-established and stable then the local system can re-sync with the grid and recover switch 17, connecting the local grid with the larger one again. Demand-side management is an important function of a modern electrical system design and is an integral part of solving this more difficult electrical system management problem. The present invention can perform demand-side management with load priority. Where the most important loads are maintained first and as more power becomes available more loads are reset. Demand-side management can help reduce the number of full or partial power outages by removing non-priority loads when it detects signals from a weak grid (voltage drop, line frequency drop, etc.) or being instructed by the grid to do so.
    [051] Sequencing and prioritization of fixed loads. This has a profound effect on current electrical systems during restoration in a power outage. With higher and higher levels of distributed generation sources expected in electrical systems, coordinating and synchronizing these many sources becomes increasingly difficult. Especially in systems dominated by distributed sources where the grid connection is weak and cannot be used as a synchronization source. Where in the present scheme loads are removed leaving only those with the highest priority, this makes the load side weak and allows the grid connection to function as the synchronization source for the distributed sources. As more sources become available more loads on the priority structure are reinstated. Again, this provides a natural and transparent way to solve a very difficult power grid problem. And more can be done with little or no communication. BRIEF DESCRIPTION OF THE DRAWINGS
    [052] An embodiment of the invention will now be described in conjunction with the accompanying drawings in which:
    [053] Figure 1 is a schematic illustration of an electrical network according to the present invention.
    [054] Figure 2 is a schematic illustration of the power correction circuit of Figure 1.
    [055] Figure 3 is a schematic illustration of an electrical network according to the present invention similar to that of Figure 1, but including additional features.
    [056] Figure 4 is a schematic illustration of the power correction circuit of Figure 3.
    [057] Figure 5 is a schematic illustration of a half-bridge to be used in the arrangement of Figures 3 and 4.
    [058] Figure 6 is a schematic illustration of an electrical network similar to that of Figure 1 showing an arrangement where compensators are built inside the outputs.
    [059] In the drawings, the same reference characters indicate corresponding parts in the different figures. DETAILED DESCRIPTION
    [060] An electrical power transmission network 10 includes a power supply 11 generally in a transformer supplying one or more transmission lines 12 and managed by a network control system 9 using many systems to detect network parameters and to control various network components to maintain voltage stability on transmission lines.
    [061] On the transmission line are a plurality of subscriber dependencies 13 for receiving electrical power, each including a plurality of user devices 14 in a power supply circuit 15. Each of the subscriber dependencies 13 has a drop 16 from the transmission line to a power supply input board 17 typically including a main input control switch. Typically at the drop a meter is provided to measure energy usage. In the present invention the meter is replaced by an integral component defining a load control device 18 connected to the power supply input 17 to control power supplied from the power supply input to user devices on the power supply circuit. power supply 15.
    [062] Each load control device includes a detection system 19 to detect variations in power factor caused by user devices 14, a power correction system 20 to apply load corrections to the power supplied by the drop to the subscriber and a control system 21 for controlling the power correction system in response to detected variations. The control system 21 connects to a communication system 91 to communicate between the load control device 19 and the network control system 9.
    [063] The detection system comprises a first gauge 22 and a second gauge 23 each of a generally known construction. Each acts to monitor the power supply waveform and to generate data related to the true RMS standard voltage and current values related to True Power. The detection system may also have systems which generate data related to FFT spectra of the power supply waveform by analyzing the waveform using conventional Fast Fourier Transform techniques. This can also be used to generate data reporting Total Harmonic Distortion (THD).
    [064] The first meter is located at the drop and the second meter is located downstream of the power correction system and the control system 21 which receives data from both acts to compare the data emitted from the second meter with the data emitted from the first meter to determine a level of improvement in power factor obtained by the power correction system 20.
    [065] The load control device is arranged to communicate data related to the measured improvement and the Actual Power consumed to the grid control system 9. This can be done in real-time, but is typically periodic.
    [066] As shown in Figure 2, the power correction system 20 comprises switched capacitor banks 24 including a switch 25 operated by control 21 which switches selected capacitors 26 in a binary switching system. System 20 additionally includes a switched reactor circuit 38 for voltage correction. This includes an inductor 28 and a switch 29 connecting the inductor across power supply buses 30 and 31. Switch 29 is operated by control 21 in response to a prominent power factor, provides greater power factor control by varying the angle trigger. Typically systems overcompensate the power factor with capacitors and use the commutator ballast combination to fine tune the power factor to unity. System 20 additionally includes an active power factor correction circuit 40 for noise correction and current shape shaping. This is composed of a rectifier 41 through supply buses 30 and 31 feeding an inductor 42 with a switch 43 connected to the rectifier return forming an amplifier circuit. Output from the amplifier circuit feeds diode 44 and holding capacitor 45. Switch 43 is operated by control 21 in response to noise and FFT analysis of downstream loads. A sine waveform of the fundamental frequency minus the sum of FFT waveforms minus the fundamental is used as the input to switch 43 modulated to a high frequency. This circuit 40 shapes the shape of load current in a sinusoid based on noise measured from downstream loads. The charge deposited on capacitor 45 can be bled off with a resistor (not shown), fed to a local solar/wind battery charging system, or reversed back onto the supply bus.
    [067] The load control device additionally includes a system for disconnecting certain devices determined from among the user load-shedding devices provided by a switch 33 operated by the control 21.
    [068] The control system includes a processor which is programmable from an external input from the communication system or is programmed to change the response to variations detected by the detection system so that the response is different under different circumstances. . In this way the entire system can be interactive or it can be adaptive to provide improved response to better manage the entire system depending on various aspects such as time of day and voltage levels locally or globally in the system.
    [069] In particular, the control system is operated by its program to change the drop voltage by changing the capacitive load in response to data from the mains control system or other factors so as to provide another tool for the control system. network management to better control voltages and to better maintain stability.
    [070] Some or all of the subscriber premises may include a power supply system at the subscriber premises to add power to power. This may comprise any of the known power supply systems such as solar panels, generators and other on-site systems. For example, the power supply as shown includes a solar generator 35 connected to a battery bank 36 operated by a switch 37 controlled by control 21 to take power from the drop 16 or to add power to the drop depending on data and or program instructions from sensor system 19 or from control network 9. In this way the control system is arranged to control the capacitor banks and the energy added by the power supply system in response to detected variations .
    [071] Dual meter structure 22, 23 enables compensation of visible loads and conditions preventing any opportunity for over-compensation. And from that any possibility of instability created by the device's compensation actions. The device is inherently stable by design and can only provide compensation or actions that will improve system stability. All this is done without the need for communication with any other device, control of electrical network, etc. This has a profound effect on network security. Hence the interruption of the electrical network by command of these (potentially millions of) devices causing damage to the system is impossible.
    [072] Returning now to Figures 3 and 4, an arrangement for connecting solar panels 351, wind generators 352, other energy sources 353 and battery banks 354 to the power correction circuit 20 is shown. In Figure 4 an arrangement for the connection is provided which includes a series of current inverters 355, 356 and 357 arranged in a row along a pair of conductors 358 and 359. A pair of current inverters is also connected through these conductors. 361 and 362. A capacitor 363 is also connected to leads 358, 359 and located between current inverters 361 and 362.
    [073] The construction of each current inverter is shown in Figure 5 and comprises an upper switch and suppressor diode 364 and the lower switch and suppressor diode 365 connected through conductors 358, 359, where the relevant intake from the power source is connected to 366. When connecting to an input power source such as a solar panel, wind generator, or charged battery, the inverter acts as an amplification regulator. Typically the DC link voltage is much higher than the voltage sourced from fixed renewable energy sources, hence an amplification conversion is necessary. The return or ground of the renewable energy source(s) is connected to point 359. The lower switch is turned on until a desired current “I” measured with 367 is developed through the inductor 368. The lower switch 365 is then off. The inductor has a stored charge which will now discharge through the suppressor diode of the upper switch 364, charging the DC link capacitor 363 connected between points 358 and 359 and finally completing the circuit by returning to the connected power source. . In this way the DC Link capacitor 363 is charged with energies that can be inverted back into the AC system via inverters 361 and 362 shown in Figure 4. To reverse this process and charge a battery the inverter current acts as a step-down converter, transferring energy from a high direct current voltage source to a lower voltage. Again, the negative battery terminal is attached to point 359. To charge a battery, power from the DC Link Capacitor 363 and buses 358 and 359 the upper switch 364 is turned on until a voltage at the terminal 366 is reached which is suitable for charging the fixed battery. This also creates an upward current within inductor 368 and is the charging current for the battery. Then the upper switch is turned off, this current continues to charge the battery through the suppressor diode of the lower switch 365, inductor 368, until the voltage/current drops to a point, where once again the upper switch is turned on, repeating the cycle. The current inverter now functions as a step-down converter, reducing the DC link capacitor voltage to a level required by the fixed battery. Both amplifier and step-down conversion cycles are well known in the industry as a way to transfer power between two DC voltages in a DC converter.
    [074] Using current inverters as the compensation element significantly improves the flexibility and stability of the arrangement. With the current inverter or Universal Compensator any passive element or combination of (capacitor, resistor, inductor and negative resistor) can be implemented with software using this structure. Current injection feedback control avoids any resonant interaction with external system components highlighting its inherent stable characteristic. Frames are constructed from half-bridges 364, 365 which interface direct current link buses 358, 359 with alternating current systems or renewable energy sources 351 to 354. Current inverters are constructed with half-bridges to interface with any number of alternating current phases or renewable energy sources. At a minimum, only one half-bridge is required to interface with a renewable energy source such as solar, wind or battery with a direct current link bus. This structure has a natural modular design topology where additions to the compensator can be made as needed. Multiple half-bridges can be mounted in parallel as shown in Figure 4 to maintain an AC phase or power source to increase current transfer capability and reduce operating noise through interleaving techniques.
    [075] As shown in Figures 1 and 3, the Injection Current Compensation uses a two meter structure 22, 23 with the compensation injected between these two meter points. When power flows from the system to the service side, a compensating action is determined by service meter 23. Injection of correction currents enables the entire service side to appear from the systems side (meter 22) as a resistive load (PF=1). The power factor and harmonic content cleanup correction has a great benefit to the system. The margin of stability is significantly increased and systems with older relay equipment benefit from the removal of undetectable harmonics. As local renewable energy sources 351 to 354 are added to the service side, energy will flow to both the system and the service loads 14. With the present two meter structure and injecting renewable energy once again between these two measuring points in the power correction circuit 20 as shown in Figure 4, the flow of this power can be measured and conditioned using the current injection inverter used for compensation.
    [076] The system acts as a universal compensator where the dual meter structure is particularly useful in this instance to enable reverse power flow. Connecting a renewable source such as solar panels, wind generators and batteries at the offset point between the two meter structure using a generic half-bridge. This enables the inverter to not only compensate for VARs but to inject real power from these renewable sources and add the required VAR compensation for these sources before they are injected into the system. The dual meter 22, 23 enables tracking of this actual power, the amount and where it is delivered from, whether to the system, service or both. This is an important distinction from currently available systems where delivered energy is metered, but without VAR tracking and compensation. And if VAR compensation is provided, a communication network as provided by communication system 91 to network 9 is required to provide Energy and VAR orders. However, in the present invention a communication system 91 is not required for the device to provide VAR compensation and maintain system stability.
    [077] The present invention can be packaged inside local output receptacles as shown in Figure 6. Where each panel breaker 600 originates a wiring path with multiple output compensation modules 601 connected along the wiring path . This forms a distributed compensation arrangement. Each module may contain a communications interface 691 to communicate with a panel mounted compensator via the communications interface 91 and/or with other similar units. Again the dual meter structure within each module enables the need for compensation and compensation results to be measured at each location along the trajectory. With communications all units can share this information to enable the group to maximize distributed netting efficiency. Without communications, a natural sharing mechanism for this information is provided by being placed along the wiring path. If a series trajectory is assumed then the module furthest from the circuit breaker is isolated, where that module can only see the loads attached to its output locations 602. Each module beyond the furthest one can see the effects and loads of every module even further. far from the panel he himself. This allows compensation to be added to loads further down the chain that might not be compensated by their local modules. While the compensation efficiency would not be as efficient as modules with communications, the added cost and complexity could be unwarranted. This distributed compensation arrangement can increase the capacity of the panel breaker and associated wiring by generating a VAR requirement of loads locally. So the interrupt only needs to carry the real power needed by these loads. Unlike before, the interruption had to carry the real and imaginary energy needs of each load. This can be significant, increasing energy transfer by 20-30% or more. All without violating established electrical codes for wiring current capacity. This can have a big impact on older installations and homes where minimal wiring was installed and a higher power requirement was not anticipated. Now, with the installation of compensating output modules, more useful energy can be carried by the same old cables installed many years ago, giving new life to older structures.
    [078] Demand-side management and prioritization of load identification and management functions require the 691 communications interface. Demand-side load commands are received by each module and the appropriate loads are either fixed or separated. depending on order. With a power grid control communications link such as 9 thinner electrical system demand management schemes are possible where millions of loads can be identified by importance, class (chargers, heating, cooling, etc.) , size, noise content, etc. This would enable greater and finer control of load profiles to match grid power availability, time of day, and energy types, renewable or grid, etc. Upon a power cut, all non-priority loads are removed. With power returning loads can be reset in order of priority to match current power availability criteria. Demand-side management and load sequencing can make a big difference to system reliability and stability, especially on power grids with a high concentration of renewable energy sources.
    权利要求:
    Claims (15)
    [0001]
    1. Load control device (18) for use in an electrical power transmission network (10), wherein the network comprises: a plurality of subscriber dependencies (13) for receiving electrical power, each including a plurality of of user devices (14) in a power supply circuit (15), at least some of which cause power factor variations when operated; transmission lines (12) supplying electrical power with each of the subscriber dependencies (13) having a drop (16) from one of the transmission lines to a power supply input (17); the load control device (18) being arranged for connection to a respective input among the power supply inputs (17) to control the power supplied from the respective power supply input to the user devices (14) ) in the respective power supply circuit (15); the load control device comprising: a detection system (19) for detecting variations in power factor caused by user devices; a power correction system (20) for applying reactive compensation components, wherein the components comprise a capacitive load, for the power supplied by the drop (16) to the subscriber premises (13); and a control system (21) for controlling the power correction system (20) in response to detected variations; CHARACTERIZED by the fact that the detection system comprises a first meter (22) generating data on the fall and a second meter generating data downstream of the power correction system, where both the first and second meters (22, 23) generate data on the same parameters obtained from the power supply circuit (15) and where the first and second meters generate data related to Real Power and in which the control system (21) is arranged to compare the data from the second meter (23) with the data from the first meter (22) to determine a level of improvement in power factor obtained by the power correction system (20).
    [0002]
    2. Load control device, according to claim 1, CHARACTERIZED by the fact that said first and second meters (22, 23) generate data related to FFT spectra of the power supply waveform.
    [0003]
    3. Load control device, according to any one of the preceding claims, CHARACTERIZED by the fact that said first and second meters (22, 23) generate data reporting Total Harmonic Distortion (THD).
    [0004]
    4. Load control device, according to any one of the preceding claims, CHARACTERIZED by the fact that the reactive compensation components comprise banks of static or switched capacitors.
    [0005]
    5. Load control device according to any one of the preceding claims, CHARACTERIZED by the fact that the reactive compensation components comprise a switched reactor.
    [0006]
    6. Load control device, according to any one of the preceding claims, CHARACTERIZED by the fact that the power correction system (20) uses a sinusoidal reference signal minus an error signal which provides correction pulses for Active Power Factor Control that shapes the input current into sine waves removing power noise and improving power quality.
    [0007]
    7. Load control device, according to any one of the preceding claims, CHARACTERIZED by the fact that a system is provided for disconnecting certain devices determined from among the user devices (14) for load shedding.
    [0008]
    8. Load control device, according to any one of the preceding claims, CHARACTERIZED by the fact that the control system (21) is programmable to change the response to variations detected by the detection system (19).
    [0009]
    9. Load control device, according to any one of the preceding claims, CHARACTERIZED in that it includes at least one power supply system (35, 36) at the subscriber premises to add power to the power from the and where the control system is arranged to control the reactive compensation components and the power added by the power supply system in response to detected variations.
    [0010]
    10. Load control device, according to claim 9, CHARACTERIZED in that said at least one additional power source (35, 36) is connected between the first and second meters so that the first and the second second meters provide tracking of added power from said at least one additional power supply.
    [0011]
    11. Load control device, according to any of the preceding claims, CHARACTERIZED by the fact that reactive compensation is performed by a current inverter (355).
    [0012]
    12. Load control device, according to claim 11, CHARACTERIZED by the fact that the current inverter (355) comprises one or more half-bridges (364).
    [0013]
    13. Load control device, according to any of the preceding claims, CHARACTERIZED by the fact that the load control device (18) is arranged after a power blackout to restore priority loads before other loads .
    [0014]
    14. Load control device, according to any one of the preceding claims, CHARACTERIZED by the fact that the power correction system includes an inductor (28) connected by a switch (29) which is operated multiple times per cycle to shape the current waveform into sine waves in phase with the voltage wave.
    [0015]
    15. Load control device, in accordance with any of the preceding claims, CHARACTERIZED by the fact that the power correction system corrects a waveform of the power supply circuit (15) to remove distortions arising from variations on the power factor of said at least one of the user devices (14).
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    同族专利:
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    EA201790903A1|2017-10-31|
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    NZ731719A|2020-10-30|
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    JP2017531988A|2017-10-26|
    EP3210274A4|2018-04-18|
    KR20170072315A|2017-06-26|
    MX2017005119A|2017-09-15|
    EP3210274A1|2017-08-30|
    ZA201701135B|2018-12-19|
    DK3210274T3|2021-03-08|
    US20160118792A1|2016-04-28|
    CN107112758B|2020-01-07|
    TW201633658A|2016-09-16|
    TWI633732B|2018-08-21|
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    CN107112758A|2017-08-29|
    SG11201702927QA|2017-05-30|
    CA2964496C|2020-11-24|
    EP3210274B1|2020-12-02|
    IL251634A|2021-04-29|
    AU2015336908B2|2019-07-25|
    CA2964496A1|2016-04-28|
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    法律状态:
    2020-06-23| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2021-12-14| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2022-02-01| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 22/10/2015, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    US14/521,971|US9634489B2|2014-10-23|2014-10-23|Electrical power transmission network|
    US14/521,971|2014-10-23|
    PCT/CA2015/051069|WO2016061687A1|2014-10-23|2015-10-22|Electrical power transmission|
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