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    • 专利摘要:
    Method and control system of a high voltage multilevel modular dc converter. Method and control system of a multilevel modular converter (500) for high voltage direct current transmission. The multilevel modular converter (500) has an input voltage (vdc) and an output voltage vector {image-01} whose possible values define a plurality of hexagons. Also, the multilevel modular converter (500) is configured to provide a load with a load voltage vector {picture-02} and a load current vector {picture-03} with respect to an absolute origin (0). The method and system comprises calculating a displaced output voltage vector of reference {image-04} with respect to a displaced origin (0 '), from the current increase vector {image-05} the input voltage (vdc) and a vector equation that describes a connection between the multilevel modular converter (500) and the load. The offset origin (0 ') is calculated in turn as a center of a hexagon closer to the load voltage vector {picture-02}. Finally, the displaced reference voltage vector of reference {picture-04} is transferred back to the absolute origin (0). (Machine-translation by Google Translate, not legally binding)
    公开号:ES2616274A1
    申请号:ES201730394
    申请日:2017-03-22
    公开日:2017-06-12
    发明作者:Dionisio Ramirez Prieto；Fernando Martinez Rodrigo；Luis Carlos Herrero De Lucas；Santiago De Pablo Gomez
    申请人:Universidad Politecnica de Madrid；Universidad de Valladolid；
    IPC主号:
    专利说明:

    Method and control system of a multi-level modular DC converterhigh voltage5
    Object of the invention
    The present invention relates to the field of power electronics, and more specifically to the technical sector dedicated to electronic converters for
    10 high voltage applications.
    Background of the invention
    Traditionally, the types of converters used in current transmission
    15 high-voltage continuous (HVDC) of the English 'High Voltage Direct Current' most commonly are the line-switched converter (LCC) of the English 'Line-Commutated Converter') and the converter in voltage source (VSC) Voltage Source Converter). The latter can present both two-level and multilevel topologies. For example, US 2014/0268926 A1 and US 2006/0282239 A1 present two converters for transmission
    20 HVDC according to multilevel LCC and VSC topologies respectively.
    However, recent research has led to the multilevel modular converter (MMC) topology, which presents the advantages of capacitive energy storage distribution, scalability, high switching frequency, and the possibility of Remove filters and transformer. On the contrary, MMC converters require a large number of semiconductors and drivers, in addition to storing more energy than in VSC converters with two or three conventional levels. For example, US 2016/0336751 A1 presents an MMC topology for HVDC with six bridges and after phases; while CN 10,217,0140 A presents a method
    30 to start the operation of this type of devices. In addition to HVDC transmission, MMC converters can be applied to motor drives, synchronous static compensators (STATCOM), back-to-back converters, solar and wind generation, and matrix converters, among others.
    35 Likewise, various techniques for controlling the tension of


    output of a converter of the HVDC-MMC type:
     Control by pulse width modulation (PWM) mult Pulse-Width modulation ’) multilevel. This method takes a reference of output voltage as a starting point, calculates the average value of the reference voltage in each period
    5 of PWM, and determines the time that each of the n MMC modules must be active (ON) for the average output value to be desired.
     PWM control with carrier phase shift. It is based on the comparison of the reference of the output voltage with a number of triangular carriers equal to the number of modules that make up each branch of the converter.
    10  Predictive control. Calculate, for each switching period, a cost function for each of the status combinations of the n modules of the MMC converter. Next, select the status with the lowest cost function.
     Current generation and feedback of the generated current. It is based on the use of hysteresis bands within which the current generated by the converter evolves.
    Although the techniques described control the alternating current (AC) voltage of the HVDC-MMC converter output, it would be desirable to be able to control the converter currents, thus regulating the active power, the reactive power and / or the
    20 DC voltage. The currents of the converter can be controlled indirectly by regulating the AC output voltages of the converter, but the resulting control is slower, which is particularly critical in case of network failures.
    Therefore, there is still a need in the prior art for a method and control system of HVDC-MMC converters capable of providing a fast and efficient control of the converter currents. Likewise, it is desirable to maintain a good harmonic spectrum in the waveform of the output current and minimize the computational load associated with the control of the converter.
    Description of the invention
    The present invention solves the problems described above by means of a rapid current control technique generated by an MMC converter, suitable for HVDC, 35 in which the classic current control loop and the decoupling block of the voltage equations are replaced by a single non-linear vector current control block. How


    The result is a very fast transient response, combined with a better harmonic spectrum in the current waveform compared to a classic hysteresis band control.
    In a first aspect of the invention a control method of an MMC converter suitable for HVDC applications is presented comprising:
     Measure a load voltage vector and a load intensity vector supplied to a load, preferably acting as a load on an electrical network of an HVDC application.
    10  Calculate a displaced origin, as a value, from among a plurality of possible values of the output voltage vector, closest to the load voltage vector. Said plurality of possible values is preferably defined in a three-phase space, so that the calculation of the displaced origin can be understood as the selection of a center of the hexagon closest to a load voltage vector, of all the
    15 hexagons defined by the possible values of the MMC output voltage vector. Said load voltage vector comprises the three-phase components of the voltage provided to the load. Said load is preferably a power grid connected according to the HVDC configuration. Preferably, the method may comprise measuring said load voltage vector, as well as the voltage vectors
    20 (ie, the three-phase components of the voltage at the output terminals of the MMC) and associated load current vector (i.e., the three-phase components of the intensity provided to the load.
     Calculate a displaced load voltage vector by moving the load voltage vector to the displaced origin. Note that the bulk of the calculations in procedure 25 are made with respect to a displaced origin, rather than with respect to the absolute origin,
    as would be the case with traditional control methods.
     Calculate a current increment vector as a difference between a reference load current vector (or target) and a load current vector provided by the MMC. Preferably, this step is performed periodically
    30 each calculation cycle until the current increase vector module exceeds a threshold, thus defining a hysteresis band. Also preferably, this step is performed on a plane defined by an absolute horizontal axis and an absolute vertical axis referred to an absolute origin.
     Calculate a displaced reference voltage vector (or target) from the current increment vector, an MMC input voltage and a vector equation that describes a connection between the multi-level modular converter and the


    load. Preferably, in this step the displaced output voltage vector of the reference is calculated as a point of intersection between a line that passes through one end of the displaced load voltage vector and follows the same direction of the current increase vector, and a circumference with center at the origin
    5 displaced. Preferably, the radius of the circumference may be equal to or greater than that of a circumference circumscribed to one of the hexagons. Preferably, this calculation includes the calculation of a single square root, which allows to reduce the computational load and the calculation time.
     Calculate a reference output voltage vector (or target) by moving the vector 10 offset output voltage of reference to the absolute origin.
     Calculate configuration parameters from the reference output voltage vector, that is, configure the MMC so that its output voltage vector evolves into the reference output voltage vector. The configuration parameters are preferably three output voltage vectors and their three
    15 associated application times, calculated using a multilevel spatial vector modulation (SVM) algorithm. In this way, the linear combination of the three output voltage vectors in their three associated application times generates an output voltage equal to the reference output voltage vector.
     Apply the configuration parameters to the multi-level modular converter.
    In a second aspect of the invention there is presented a control system comprising calculation means and configuration means adapted to determine and apply configuration parameters of an MMC from an input voltage, a load voltage vector, a load current vector and a plurality of possible values of a
    25 vector output voltage.
    In particular, the calculation means are configured to:  Calculate the displaced origin as a possible value of the output voltage vector closest to the load voltage vector, as described in the first aspect of the
    30 invention.  Move the load voltage vector to the displaced origin.  Subtract the reference load current vector and the load current vector for
    get the current increase vector.  Calculate the displaced reference voltage output vector from the current increase vector 35, the input voltage and the vector equation describing the connection between the multi-level modular converter and the load.


     Move the displaced output voltage vector of reference to the absolute origin.
    On the other hand, the control means are configured to calculate configuration parameters from the reference output voltage vector and apply the configuration parameters to the MMC. In addition, preferably, the system further comprises a
    subset or all of the following elements:  A multilevel spatial vector modulator configured to calculate the configuration parameters previously described.  A phase tracking loop configured to calculate an angle () of a Park transformation from three-phase components of the load voltage vector.
     A first proportional-integral regulator (PI) and a second PI controller configured to calculate the components of the reference load current vector from an active power and a reactive power.
    15 Note that any particular preferred option or implementation of the system of the invention can also be applied to the method of the invention. Likewise, the elements of said system can be adapted or configured to implement any step of the method of the invention, according to any implementation.
    20 particular of both.
    Finally, in a third aspect of the invention there is presented a computer program comprising computer program code means adapted to implement the described method, when an integrated circuit is executed in a digital signal processor
    Application-specific, a microprocessor, a microcontroller or any other form of programmable hardware. Note that any preferred option and particular implementation of the device and system of the invention can be applied to the method and computer program of the invention, and vice versa.
    The method, system and computer program of the invention calculate the voltage value necessary to generate the desired current in each application quickly, reducing the computational load, the amplitude of the generated harmonics, losses in generators and mechanical stress. produced in the windings. These and other advantages of the invention will be apparent in light of the detailed description thereof.


    Description of the figures
    In order to help a better understanding of the features of the invention ofaccording to a preferred example of practical realization thereof, and for5 complement this description, they are accompanied as an integral part of itfollowing figures, whose character is illustrative and not limiting:
    Figure 1 shows a schematic of a three-phase, five-level MMC, known in the state of the art.
    10 Figure 2 presents an example of an MMC module implementation, in semi-bridge configuration, known in the state of the art.
    Figure 3 exemplifies a connection of the MMC to an electrical network through inductances, known in the state of the art.
    Figure 4 illustrates a power control scheme for an MMC with PI regulators for active and reactive power, known in the state of the art.
    Figure 5 shows the voltage and current measurement elements used by a preferred embodiment of the present invention, as well as a possible application scenario formed by an MMC and the network to which it is connected.
    Figure 6 shows the control elements that determine the gate signals of the MMC converter from the measured parameters, in accordance with a preferred embodiment of the invention.
    Figure 7 shows in greater detail a possible implementation of the PLL of the invention.
    30 Figure 8 exemplifies the possible values of the output voltage vector of a five-level MMC converter.
    Figure 9 exemplifies the process of calculating the reference voltage vector of the converter from the vectors of the mains voltage, the mains current and the reference of the mains current, in accordance with a preferred embodiment of the present invention.


    Figure 10 shows the same vectors of Figure 9, but within the framework of the output voltage levels that can be achieved with the converter.
    Preferred Embodiment of the Invention
    In this text, the term "comprises" and its derivations (such as "understanding", etc.) should not be understood in an exclusive sense, that is, these terms should not be construed as excluding the possibility that what is described and defined can include more elements, stages, etc. Note also that vectors and components accompanied by the term "reference" should be understood herein as objective values for said vectors and components, said objectives being calculated by the method and system of the invention. That is, said "reference" vectors and components are not external fixed value references, but rather have variable values that can change in successive iterations of the calculations performed by the invention.
    Figure 1 shows an MMC converter (500) for HVDC known in the state of the art, which serves as an example of application of the method and system of the invention. In particular, it is a three-phase MMC with six branches (R1, R2, R3, R4, R5, R6) and five modules (also called SM, of the English 'Switching-Module') per branch (SM1, SM2, SM3, SM4, SM5). The DC area of the converter has an input voltage (vDC), divided into two symmetrical voltages (+ vDC / 2, -vDC / 2). The first branch (R1), second branch (R2) and third branch (R3) are connected to the positive symmetric voltage (+ vDC / 2); while the fourth branch (R4), the fifth branch (R5) and the sixth branch (R6) are connected to the negative symmetric voltage (-vDC / 2). In turn, the branches are connected two by two through pairs of inductances (L), establishing an output voltage vector (⃗) with three three-phase components (,,).

    Figure 2 shows a possible realization of an SM (denoted as SMk as being valid for any of the five sub-modules of each branch: SM1, SM2, SM3, SM4, SM5) called semipuente (in English ‘half-bridge’). The semipuent topology comprises a first transistor (T1) connected in parallel to a first diode (D1) and a second transistor (T2) connected in parallel to a second diode. The anode of the first diode (D1) is connected to the cathode of the second diode (D2) serving as the entry point of the submodule current (iSM) and first terminal of the submodule voltage (vSM). In turn, the cathode of the first diode (D1) is connected to the anode of the second diode (D2) through a capacitor (C) with a capacitor voltage (vc). Said anode of the second diode acts


    in turn as the second terminal of the submodule voltage (vSM).
    Figure 3 exemplifies the connection of the MMC converter (500) to a network (acting as a load) by means of three filter inductances (Lc). After the three filter inductances (Lc), the output voltage vector (⃗) becomes the charge voltage vector (⃗) with three-phase component paths (,,). The intensity of

    input (iDC); the three-phase components (,,) of the charge intensity vector (⃗); the voltage of the upper branch (vua) and the intensity of the upper branch (iua) corresponding to the first branch (R1); and the lower branch voltage (vla) and the intensity of the lower branch (ila) corresponding to the fourth branch (R4).
    Figure 4 shows power regulation means (600) for MMC converters (500). Said power regulation means (600) comprise a calculation module
    (610) which calculates the active power (P) and the reactive power (Q) from the
    three-phase components (,,) of the load voltage vector (⃗) and the components

    three-phase (,,) of the charge intensity vector (⃗). The active power (P) and the reactive power (Q) are then subtracted from the active reference power (P *) and the reactive power reference (Q *) in a first subtraction module (620) and a second module subtraction (621). The resulting differences serve as input to a first proportional-integral regulator (PI, 630) and a second PI regulator (631), thus obtaining the direct axis component (id *) and the quadrature component (iq *) of the current vector from

    reference network (∗ ⃗). Alternatively, the regulation can be carried out on the direct current (vDC) instead of on the active power (P). Note that the active reference power (P *) and the reactive reference power (Q *) are input parameters, provided by a user or by another auxiliary system depending on a general energy transfer control strategy.
    Figure 5 shows the measurement and conversion means comprised by a preferred embodiment of the system of the invention, which in turn execute steps of preferred embodiments of the method and the computer program of the invention. In particular, the system comprises a first conversion element (710) and a second conversion element
    (711) that transfer the inputs of three-phase axes (abc) to horizontal-vertical axes (). In particular, the first conversion element (710) calculates a horizontal component (i) and a vertical component (i) of the current network vector (⃗) from the three three-phase components (,,) of the current vector of network (⃗). The second element of

    conversion (711) calculates a horizontal component (v) and a vertical component (v) of the


    mains voltage vector (⃗) from the three-phase components (,,) of the voltage vector

    of load (⃗). Finally, a phase tracking loop (720, PLL) of the English 'Phase-Locked Loop' calculates an angle () for a Park transformation from the three-phase components (,,) of the load voltage vector (⃗) . Also shown in the figure are control parameters (501) of the MMC converter (500), calculated from said horizontal component (v) and a vertical component (v) of the voltage vector of

    network (⃗); horizontal component (i) and a vertical component (i) of the grid current vector (⃗) and angle ().
    Figure 6 shows a preferred embodiment of the elements that calculate the control parameters (501). These elements comprise a third conversion element (730) that moves from a direct-quadrature axis (dq) to the horizontal-vertical axes (). In particular the third conversion element (730) calculates a horizontal component
    ∗
    (i *) and a second vertical (i *) of the reference network intensity vector (⃗) from
    angle (), and the direct axis component (id *) and quadrature component (iq *) of the vector
    ∗
    reference network intensity (⃗). The vertical and horizontal components of the reference network intensity vector (∗ ⃗), the network voltage vector (⃗) and that of the network intensity vector (⃗) are introduced in calculation means (740), obtaining a horizontal component (vo *) and a vertical component (vo * ) of the reference output voltage vector
    ∗
    (⃗). The calculation means (740) are preferably a non-linear multilevel controller. Finally, some control means (750), preferably formed by a multilevel spatial vector modulator (SVM), calculates the
    ∗
    control parameters (501) from the reference output voltage vector (⃗).
    Figure 7 shows in greater detail the phase tracking loop (720), which comprises a fourth conversion element (712) that moves from the three-phase axes (abc) to the horizontal-vertical axes (); and a fifth conversion element (731) that moves from the horizontal-vertical axes () to the direct-quadrature axes (dq). The direct axis component (vd) and the quadrature component (vq) of the load voltage vector (⃗) are thus obtained from the three-phase components (va, vb, vc) of said load voltage vector (⃗). The quadrature component (vq) of the load voltage vector (⃗) is in turn introduced into a third PI regulator module (760). The output of the PI regulator module (760) is added to an offset frequency (offset) in an adder (770) obtaining a total frequency (). The total frequency (), in turn, is entered into an integrator (780) that obtains the angle (), and which in turn feeds the fifth conversion element (731). The offset frequency value ( offset)


    it is entered manually according to the predictable frequency value for the mains voltage so that the PLL takes less time to stabilize.
    In order to exemplify the vector calculations described, Figure 8 shows the set of values that the output voltage vector can take in a five-level converter. Each possible vector therefore comprises three components, each component being between levels 0 and 4. Each of said possible vectors forms the vertex of a triangle which, in turn, forms a plurality of hexagons.
    Figure 9 exemplifies the translation from absolute horizontal-vertical axes (), centered on the absolute origin (0), to displaced horizontal-vertical axes (’ ’) centered on a displaced origin (0’). The rest of the variables involved in the calculation are detailed below, during the description of the steps of the preferred implementation of the procedure. Unlike the case of two-level converters, the vectors used in the calculations of the invention are calculated with respect to an absolute origin that does not have to coincide with the center of the set of hexagons that make up the possible solution vectors. Thus, in each cycle, considering all the hexagons, the hexagon whose center is closest to the grid voltage to which the converter is connected is chosen as the displaced origin (0 ’). The solution obtained is referenced with respect to the absolute origin (0), adding a displacement vector (⃗) that joins the absolute origin (0) and the displaced origin (0 ’).
    Finally, figure 10 superimposes the information of figures 8 and 9, for the particular example in which the origin (0) is located at a first output voltage value
    (000) and travels to a displaced origin in a second output voltage value (210).
    The steps of a preferred embodiment of the method of the invention are detailed below, which are in turn implemented by a preferred embodiment of the calculation means (740) and control means (750) of the system. The method comprises:
    i. Calculate the displaced origin (0 ’) as the output voltage vector closest to the value of the load voltage vector (⃗). When the MMC converter (500) is connected to a three-phase electrical network, the calculation means (740) can obtain the displacement vector (⃗) that connects the absolute origin (0) and the displaced origin (0 ’) according to the following vector equation that describes the network connection of the MMC converter (500):


    ⃗∆⃗
    ⃗ = ⃗ ++ ⃗≈∆ + ⃗,
    where t is time, and Rc and Lc are the resistance and inductance values of the network connection filter and transformer. Note that the vector equation can approximate a line to optimize computational load.
    ii. Calculate the vector of the displaced charge voltage (⃗ ′) relative to the displaced origin (0 ’) as the difference between the charge voltage vector (⃗) and the offset vector (⃗) .⃗
    ′ = ⃗−⃗
    iii. Calculate the current increment vector (∆⃗) as the difference between the current vector
    ∗
    reference network (⃗) and the current network vector (⃗):⃗∗ ⃗�
    ∆ = −⃗ = ∆i + j∆i
    where, ∆i� is the horizontal component of the current increment vector (∆⃗), ∆i� is es
    the vertical component of the current increment vector (∆⃗) and j is the imaginary unit.
    ∗
    Note that the current reference network vector (⃗) was previously obtained in the power regulation means (600).
    iv. Calculate the points of intersection (,) between the line that passes through the tension vector of
    displaced load (⃗) and is parallel to the current increase vector (∆⃗), with the

    circumference centered on the displaced origin (0) and radius ().
    That is, the line passes through the point ⃗ ′ = ′ + ′ and has a slope ∆⁄∆. Between the two points of intersection (A, B), the point of intersection is chosen that provides an evolution of the current in the same direction with respect to the displaced load voltage vector (⃗) than the current increase vector (∆⃗) . The displaced origin (0 ’) and the intersection point (A, B) chosen determine the output voltage vector
    reference offset (∗ ∗).
    When the vertical component of the current increment vector (∆⃗) is positive (∆> 0), the intersection can be calculated as:
    � �
    ∗ = + - (1 +) (-)
    (1+)
    While when the vertical component of the current increase vector (∆⃗) is negative (∆ <0), the intersection can be calculated as:
    � �
    −− (1 +) (-)
    ∗ = (1+)


    with:
    = ∆∆; = v′ − ∆∆v′�
    Note that the solutions of the intersection of the slope line ∆⁄∆� with the circumference of radius R and center at the displaced origin (0 ’) are obtained in values on the vertical axis (). Through this implementation of the algorithm the correct solution is obtained by calculating a single square root in each microprocessor cycle, which represents a considerable saving of computation time in the control. In addition, it provides a more constant cycle time, which is an advantage to predict the total computation time of the control program, essential when choosing the
    10 configuration of the sampling period of the analog-digital converters and the PWM cycle time of the SVM.
    Note also that the radius (R) may be greater than the radius of a circle circumscribed to the hexagon to give greater imposition capacity of the reference current vector (∗ ⃗). In some applications, such as wave energy, the alternating voltage on the generator side undergoes large variations due to frequent and persistent periods of low rotation speed of the generator due to low waves. In these circumstances, the electromagnetic force generated by the wave generator is also of reduced value and using a circumference of radius R or greater in a converter of the MMC type connected to the generator would cause large harmonics of
    20 current with the associated associated losses and strong mechanical stress would be generated in the windings. The horizontal component (∗ �) of the displaced reference voltage output vector (∗ ⃗) can be obtained from the equations of the line or circumference:
    ∗ = a ∗ + b = ∆i ∗ + ′ - ∆i� ′
    ∆iv∆iv
    ∗ + ∗ = �
    25 v. Reference the solution obtained, that is, the vector offset output voltage of reference (∗ ⃗) to the absolute origin by adding the offset vector (⃗):∗ ⃗ = ∗ ⃗ +⃗
    saw. Generate the configuration parameters (501) that produce an evolution of the output voltage vector (⃗) towards the reference output voltage vector (∗ ⃗). In particular,
    30 a multilevel SVM algorithm chooses in each cycle the appropriate hexagons, that is, the configuration parameters (501) of the three-phase components of the voltage vector of


    exit (⃗) and / or the switching times of the transistors that make up the MMC converter modules (500), so that the current evolves in the direction of the reference.
    5 vii. Once a cycle has elapsed, the current increase vector (∆⃗) is recalculated.When the module of the current increase vector (∆⃗) exceeds a threshold (), they are repeatedthe steps described for the calculation and application of a new output voltage vector of
    reference (∗ ⃗). Note that the resulting hysteresis spatial band is a circle around one end of the network current vector (⃗), which simplifies checking 10 if the current has exceeded the hysteresis band.
    For the particular case shown in Figure 10, it can be seen that the output voltage vector of the converter closest to the load voltage vector (⃗) is vector 210.
    After performing the steps described, the output voltage vector (∗ ⃗) calculated, is generated by combining the three closest vectors of converter output voltage: 120, 220 and 230.
    The person skilled in the art may understand that the invention has been described according to some preferred embodiments thereof, but that multiple variations can be introduced in said preferred embodiments, without departing from the object of the invention as claimed.
    one.
    2.
    3.

    权利要求:
    Claims (13)
    [1]
    Control method of a multi-level modular converter (500) for high-voltage direct current transmission, the multi-level modular converter (500) having an input voltage (vDC) and an output voltage vector (⃗) with a plurality of possible values, and the multi-level modular converter (500) being configured to provide a load with a load voltage vector (⃗) and a load current vector (⃗) with respect to an absolute origin (0); characterized in that it comprises:
     measure the load voltage vector (⃗);  calculate a displaced origin (0 ’), as a possible value of the output voltage vector (⃗) closest to the load voltage vector (⃗);
     calculate a displaced load voltage vector (⃗ ′) by moving the load voltage vector (⃗) to the displaced origin (0 ’);
     calculate a current increment vector (∆⃗) as a difference between a
    ∗
    reference load current vector (⃗) and the current charge vector (⃗); calculate a reference offset output voltage vector (∗ ⃗ ′) fromvector increase in current (∆⃗), input voltage (vDC) and an equationvector that describes a connection between the multi-level modular converter
    (500) and the load;
    ∗
     calculate a reference output voltage vector (⃗) moving the vector
    output voltage shifted from reference (∗ ⃗ ′) to absolute origin (0);  calculate some configuration parameters (501) from the voltage vector of
    reference output (∗ ⃗); Y
     apply the configuration parameters (501) to the multi-level modular converter (500).
    Method according to claim 1 characterized in that the step of calculating configuration parameters (501) is performed by means of a multilevel spatial vector modulator.
    Method according to any of the preceding claims characterized
    why the step of calculating the vector offset output voltage of reference (∗ ⃗ ′)
    it is repeated every time the module of the current increase vector (∆⃗) exceeds a threshold ().

    [4]
    4. Method according to any of the preceding claims characterized in that the step of calculating a current increment vector (∆⃗) is performed on a plane defined by an absolute horizontal axis () and an absolute vertical axis ()
    referred to the absolute origin (0).5
    [5]
    5. Method according to any of the preceding claims characterized in that the step of calculating the vector displaced reference voltage output (∗ ⃗ ′) comprises calculating an intersection point (A, B) between:  a line passing through one end of the displaced load voltage vector (⃗ ′)
    10 and follows the direction of the current increase vector (∆⃗), and  a circle with center at the displaced origin (0 ’) and radius (R).
    [6]
    6. Method according to claim 5 characterized in that the radius (R) is
    greater than the input voltage divided by √3. fifteen
    [7]
    7. Method according to any of claims 5 and 6 characterized by
    that the step of calculating the reference offset output voltage vector (∗ ⃗ ′) is performed by a single square root comprising components of the current increment vector (∆⃗) and the displaced charge voltage vector (⃗ ′).
    [8]
    Method according to claim 7, characterized in that, if the component of the current increase vector (∆⃗) with respect to the absolute vertical axis () is
    ∗
    positive, the vertical component () of the displaced output voltage vector of
    ∗
    reference (⃗ ′) is calculated as:
    � �
    ∗ � = + - (1 +) (-)
    �
    (1+) 25 and if the component of the current increase vector (∆⃗) with respect to the absolute vertical axis () is negative, the vertical component (∗ �) of the output voltage vector
    reference offset (∗ ⃗ ′) is calculated as:
    ∗ � = −− (1 +) (-)
    �
    (1+)
    with:
    = ∆∆; = v′ − ∆∆v′�
    30 where ∆i� and ∆i� are the horizontal and vertical component of the increment vector of

    current (∆⃗), and v′y v′ are the horizontal and vertical component of the displaced load voltage vector (⃗ ′).
    [9]
    9. Method according to claim 8 characterized in that the component
    ′
    horizontal ( ∗ �) of the reference offset output voltage vector (⃗ ∗) is calculated
    how: ∗ � =∗ � −v′ − ∆i∆i� ∆i∆iv′�
    [10]
    10. Method according to any of the preceding claims characterized in that the reference charge current vector (∗ ⃗) is obtained from a first proportional-integral regulator (630) that controls an active power (P) and a
    second proportional-integral regulator (631) that controls a reactive power (Q).
    [11]
    eleven. Control system of a multi-level modular converter (500) for high-voltage direct current transmission, the multi-level modular converter (500) having an input voltage (vDC) and an output voltage vector (⃗) with a plurality of possible values, and the multi-level modular converter (500) being configured to provide a load with a load voltage vector (⃗) and a load current vector (⃗) with respect to an absolute origin (0); characterized in that it comprises measuring means configured to measure the load voltage vector (⃗) and the load current vector (⃗); calculation means (740) configured to:
     calculate a displaced origin (0 ’), as a possible value of the output voltage vector (⃗) closest to the load voltage vector (⃗);
     calculate a displaced load voltage vector (⃗ ′) by moving the load voltage vector (⃗) to the displaced origin (0 ’);
     calculate a current increment vector (∆⃗) as a difference between a reference load current vector (∗ ⃗) and the current charge vector (⃗);
     calculate a reference offset output voltage vector (∗ ⃗ ′) from the current increase vector (∆⃗), the input voltage (vDC) and a vector equation that describes a connection between the multi-level modular converter
    (500) and the load;  calculate a reference output voltage vector (∗ ⃗) moving the vector

    output voltage shifted from reference (∗ ⃗ ′) to absolute origin (0); and control means (750) configured to:  calculate configuration parameters (501) from the voltage vector of
    reference output (∗ ⃗); Y5  apply the configuration parameters (501) to the multi-level modular converter(500).
    [12]
    12. System according to claim 11 characterized in that the means of
    control (750) comprise a multilevel spatial vector modulator. 10
    [13]
    13. System according to any of claims 11 and 12 characterized in that it comprises a phase tracking loop (720) configured to calculate an angle () of a Park transformation from three-phase components
    (,,) of the load voltage vector (⃗). fifteen
    �
    [14]
    14. System according to any of claims 11 to 13 characterized in that it comprises a first proportional-integral regulator (630) and a second proportional-integral regulator (631) configured to calculate a current vector
    reference load (∗ ⃗) from an active power (P) and a reactive power 20 (Q).
    [15]
    15. Computer program comprising computer program code means adapted to perform the steps of the method of any of claims 1 to 10, when said program is executed in a
    25 digital signal processor, an application-specific integrated circuit, a microprocessor, a microcontroller or any other form of programmable hardware.

     FIGURES 








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    同族专利:
    公开号 | 公开日
    ES2616274B2|2018-04-10|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    ES2371845A1|2011-06-09|2012-01-10|Universidad Politécnica de Madrid|System and method for controlling an electronic inverter as a non-linear current source|
    ES2598809A1|2015-07-30|2017-01-30|Universidad De Valladolid|Multilevel converter current source |
    ES2600757A1|2015-07-30|2017-02-10|Universidad De Valladolid|Multilevel converter with adaptive voltage |
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