MMC converter valve and super capacitor converter valve cooperative control method and device

Abstract

The invention provides a cooperative control method and device for an MMC converter valve and a super-capacitor converter valve. And in a static phase modulation mode, controlling the MMC converter valve by adopting an active frequency control mode and a voltage reactive power control mode, and controlling the super capacitor converter valve according to the voltage instruction value of the direct current bus where the direct current switch is located. And in the static synchronous compensation mode, an active frequency control mode and a voltage reactive power control mode are adopted to control the MMC converter valve. Different control modes are adopted according to different working modes of the static synchronous phase modifier, and control conflicts are avoided, so that normal operation of the static synchronous phase modifier is ensured. Under the condition that the alternating-current power grid breaks down, the technical scheme provided by the invention can enable the static synchronous phase modifier to well perform inertia support and reactive support on the alternating-current power grid, and has a flexible operation mode and an efficient utilization rate.

Description

Technical Field

[0001] The present application relates to the technical field of power systems, and specifically relates to a cooperative control method and device for an MMC converter valve and a supercapacitor converter valve. Background Art

[0002] With the accelerating process of power system construction, new energy has gradually become the main body of newly installed capacity and newly generated electricity. With the continuous increase in the new energy penetration rate, the power system is gradually showing a trend of high power electronics, and the operating mechanism and safety and stability characteristics of the previous synchronous machine-based power system are undergoing profound changes.

[0003] In order to improve the steady-state and transient stability capabilities of a power system including new energy (which can be simply referred to as a new type of power system), a static synchronous compensator (SSC) can be set in a new energy power station and an AC collection station. The SSC can utilize power electronic control technology to achieve voltage source characteristics similar to those of a synchronous compensator. Its main functions include inertia support, voltage support, short-circuit capacity support, voltage regulation, etc., to improve the power factor of the new type of power system and enhance the transient stability of the new type of power system.

[0004] Related technologies usually adopt a constant DC current control or a constant DC voltage control method to control the active power of a directly-connected energy storage converter valve or the actual value of the DC bus voltage respectively. They also adopt a constant active / constant DC voltage control and a constant reactive / constant AC voltage control to control the active power on the AC side of the MMC converter valve, the reactive power on the AC side of the MMC converter valve, and the actual value of the DC bus voltage. That is to say, related technologies usually independently control the directly-connected energy storage converter valve and the MMC converter valve, and there will be a situation where the directly-connected energy storage converter valve and the MMC converter valve simultaneously control the active power or the actual value of the DC bus voltage, that is, a control conflict occurs, resulting in the abnormal operation of the SSC. Summary of the Invention

[0005] To solve the problem of abnormal operation of the SSC in the prior art, the present application provides a cooperative control method for an MMC converter valve and a supercapacitor converter valve, which may include:

[0006] Determine the operating mode of the static synchronous compensator according to the state of the DC switch between the MMC converter valve and the supercapacitor converter valve; wherein, the operating mode includes a static phase modulation mode and a static synchronous compensation mode.

[0007] In the static phase modulation mode, the MMC converter valve is controlled by using an active frequency control method and a voltage reactive power control method, and the supercapacitor converter valve is controlled according to the voltage command value of the DC bus where the DC switch is located.

[0008] In the static synchronous compensator mode, the MMC converter valve is controlled by using the active power - frequency control method and the voltage - reactive power control method.

[0009] In some possible implementation manners, controlling the MMC converter valve by using the active power - frequency control method and the voltage - reactive power control method includes:

[0010] According to the active power command value of the grid connection point, the angular frequency command value of the static synchronous compensator, the reactive power command value of the grid connection point, and the voltage command value of the grid connection point, and combining the active power - frequency control method and the voltage - reactive power control method, calculate the AC modulation voltage of the MMC converter valve.

[0011] Determine the circulating current modulation voltage of the MMC converter valve according to the d - axis circulating current command value and the q - axis circulating current command value.

[0012] Calculate the modulation voltage of the upper bridge arm and the modulation voltage of the lower bridge arm of the MMC converter valve according to the AC modulation voltage of the MMC converter valve, the circulating current modulation voltage of the MMC converter valve, and the modulation voltage of the DC bus.

[0013] Modulate the modulation voltage of the upper bridge arm and the modulation voltage of the lower bridge arm to obtain the first control signal.

[0014] Control the MMC converter valve according to the first control signal.

[0015] In an example, according to the active power command value of the grid connection point, the angular frequency command value of the static synchronous compensator, the reactive power command value of the grid connection point, and the voltage command value of the grid connection point, and combining the active power - frequency control method and the voltage - reactive power control method, calculating the AC modulation voltage of the MMC converter valve includes:

[0016] According to the active power command value of the grid connection point and the angular frequency command value of the static synchronous compensator, and using the active power - frequency control method to control the actual active power value of the grid connection point and the actual angular frequency value of the static synchronous compensator, obtain the phase angle of the static synchronous compensator.

[0017] According to the reactive power command value of the grid connection point and the voltage command value of the grid connection point, and using the voltage - reactive power control method to control the actual reactive power value of the grid connection point and the actual voltage value of the grid connection point, obtain the voltage amplitude of the static synchronous compensator.

[0018] Calculate the AC modulation voltage of the MMC converter valve according to the phase angle and the voltage amplitude of the static synchronous compensator.

[0019] Specifically, it includes:

[0020] Determine the three - phase internal electromotive force of the static synchronous compensator according to the phase angle and the voltage amplitude of the static synchronous compensator.

[0021] Calculate the three-phase voltage command values of the connection point according to the three-phase internal electromotive forces of the static synchronous compensator and the arm reactances of the MMC converter valves.

[0022] According to the three-phase voltage command values of the connection point, and adopting a double closed-loop voltage and current control method to control the actual three-phase voltage values of the connection point, the AC modulation voltage of the MMC converter valves is obtained.

[0023] In another example, determining the circulating current modulation voltage of the MMC converter valves according to the d-axis circulating current command value and the q-axis circulating current command value includes:

[0024] Decouple and control the actual d-axis circulating current value and the actual q-axis circulating current value according to the d-axis circulating current command value and the q-axis circulating current command value to obtain the d-axis voltage command value and the q-axis voltage command value;

[0025] Perform Park inverse transformation on the d-axis voltage command value and the q-axis voltage command value to obtain the circulating current modulation voltage of the MMC converter valves.

[0026] Exemplarily, the modulation voltages of the upper arm and the lower arm respectively satisfy:

[0027]

[0028] Among them, represents the modulation voltage of the j-th phase of the upper arm, represents the modulation voltage of the j-th phase of the lower arm; represents the AC modulation voltage of the j-th phase of the MMC converter valves; represents the circulating current modulation voltage of the j-th phase of the MMC converter valves; m dc represents the modulation voltage of the DC bus; in the static phase modulation mode, the modulation voltage of the DC bus adopts the voltage command value of the DC bus; in the static synchronous compensator mode, calculate the modulation voltage of the DC bus according to the voltage command value of the DC bus.

[0029] In some other possible implementation manners, controlling the supercapacitor converter valves according to the voltage command value of the DC bus where the DC switch is located includes:

[0030] Calculate the modulation voltage of the DC bus according to the voltage command value of the DC bus.

[0031] Modulate the modulation voltage of the DC bus to obtain a second control signal.

[0032] Control the supercapacitor converter valves according to the second control signal.

[0033] Optionally, calculating the modulation voltage of the DC bus according to the voltage command value of the DC bus includes:

[0034] Perform proportional-integral control on the first voltage difference to obtain a second voltage difference; wherein, the first voltage difference is used to indicate the voltage difference between the voltage command value and the actual voltage value of the DC bus.

[0035] Superimpose the second voltage difference on the actual voltage value of the DC bus to obtain the modulation voltage of the DC bus.

[0036] On the other hand, the present application also provides a coordinated control device for an MMC converter valve and a supercapacitor converter valve, which may include:

[0037] A determination module, configured to determine the operating mode of the static synchronous compensator according to the state of the DC switch between the MMC converter valve and the supercapacitor converter valve; wherein, the operating mode includes a static phase modulation mode and a static synchronous compensation mode.

[0038] A first control module, configured to control the MMC converter valve in the static phase modulation mode by using an active frequency control method and a voltage reactive power control method, and control the supercapacitor converter valve according to the voltage command value of the DC bus where the DC switch is located.

[0039] A second control module, configured to control the MMC converter valve in the static synchronous compensation mode by using an active frequency control method and a voltage reactive power control method.

[0040] In a possible implementation manner, the first control module or the second control module is specifically configured to:

[0041] According to the active power command value of the grid connection point, the angular frequency command value of the static synchronous compensator, the reactive power command value of the grid connection point, and the voltage command value of the grid connection point, and in combination with the active frequency control method and the voltage reactive power control method, calculate the AC modulation voltage of the MMC converter valve.

[0042] Determine the circulating current modulation voltage of the MMC converter valve according to the d-axis circulating current command value and the q-axis circulating current command value.

[0043] Calculate the modulation voltage of the upper bridge arm and the lower bridge arm of the MMC converter valve according to the AC modulation voltage of the MMC converter valve, the circulating current modulation voltage of the MMC converter valve, and the modulation voltage of the DC bus.

[0044] Modulate the modulation voltage of the upper bridge arm and the lower bridge arm to obtain a first control signal.

[0045] Control the MMC converter valve according to the first control signal.

[0046] In an example, the first control module or the second control module is specifically configured to:

[0047] According to the active power command value of the point of common coupling and the angular frequency command value of the static synchronous compensator, and adopting the active frequency control method to control the actual active power value of the point of common coupling and the actual angular frequency value of the static synchronous compensator, the phase angle of the static synchronous compensator is obtained.

[0048] According to the reactive power command value of the point of common coupling and the voltage command value of the point of common coupling, and adopting the voltage reactive power control method to control the actual reactive power value of the point of common coupling and the actual voltage value of the point of common coupling, the voltage amplitude of the static synchronous compensator is obtained.

[0049] Calculate the AC modulation voltage of the MMC converter valve according to the phase angle and voltage amplitude of the static synchronous compensator.

[0050] In another example, the first control module or the second control module is specifically used for:

[0051] Decouple and control the actual d-axis circulating current value and the actual q-axis circulating current value according to the d-axis circulating current command value and the q-axis circulating current command value to obtain the d-axis voltage command value and the q-axis voltage command value.

[0052] Perform Park inverse transformation on the d-axis voltage command value and the q-axis voltage command value to obtain the circulating current modulation voltage of the MMC converter valve.

[0053] Exemplarily, the first control module or the second control module calculates the modulation voltage of the upper bridge arm and the modulation voltage of the lower bridge arm according to the following formula:

[0054]

[0055] Wherein, represents the modulation voltage of the j-phase of the upper bridge arm, represents the modulation voltage of the j-phase of the lower bridge arm; represents the AC modulation voltage of the j-phase of the MMC converter valve; represents the circulating current modulation voltage of the j-phase of the MMC converter valve; m dc represents the modulation voltage of the DC bus; in the static phase modulation mode, the modulation voltage of the DC bus adopts the voltage command value of the DC bus; in the static synchronous compensation mode, the modulation voltage of the DC bus is calculated according to the voltage command value of the DC bus.

[0056] In another possible implementation manner, the first control module is specifically used for:

[0057] Calculate the modulation voltage of the DC bus according to the voltage command value of the DC bus.

[0058] Modulate the modulation voltage of the DC bus to obtain a second control signal.

[0059] Control the supercapacitor converter valve according to the second control signal.

[0060] Further, the first control module or the second control module is specifically configured to:

[0061] Perform proportional-integral control on the first voltage difference to obtain a second voltage difference; wherein, the first voltage difference is used to indicate the voltage difference between the voltage command value of the DC bus and the actual voltage value of the DC bus.

[0062] Superimpose the second voltage difference on the actual voltage value of the DC bus to obtain the modulation voltage of the DC bus.

[0063] On the other hand, the present application also provides a computer device, including: one or more processors.

[0064] The processor is configured to execute one or more programs.

[0065] When the one or more programs are executed by the one or more processors, the cooperative control method as described above is implemented.

[0066] On the other hand, the present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed, the cooperative control method as described above is implemented.

[0067] Compared with the prior art, the beneficial effects of the present application are:

[0068] In the cooperative control method of the MMC converter valve and the supercapacitor converter valve provided by the present application, in the static phase modulation mode, the MMC converter valve is controlled by using the active frequency control method and the voltage reactive power control method, and the supercapacitor converter valve is controlled according to the voltage command value of the DC bus where the DC switch is located. In the static synchronous compensator mode, the MMC converter valve is controlled by using the active frequency control method and the voltage reactive power control method. It can be seen that the present application realizes the cooperative control of the MMC converter valve and the supercapacitor converter valve.

[0069] The present application adopts different control methods according to different working modes of the static synchronous compensator, and there will be no control conflicts, thus ensuring the normal operation of the static synchronous compensator.

[0070] In the case of a fault in the AC power grid, the technical solution provided by the present application can enable the static synchronous compensator to better provide inertia support and reactive power support for the AC power grid, and has flexible operation modes and high utilization efficiency. Description of the Drawings

[0071] To more clearly illustrate the technical solutions in the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0072] Figure 1 It is a schematic structural diagram of a static synchronous compensator in an embodiment of the present application;

[0073] Figure 2 It is a schematic flowchart of a cooperative control method in an embodiment of the present application;

[0074] Figure 3 It is a schematic flowchart of controlling the MMC converter valve by using the active power - frequency control method and the voltage - reactive power control method in an embodiment of the present application;

[0075] Figure 4 It is another schematic flowchart of controlling the MMC converter valve by using the active power - frequency control method and the voltage - reactive power control method in an embodiment of the present application;

[0076] Figure 5 It is a schematic flowchart of calculating the modulation voltage of the DC bus according to the voltage command value of the DC bus in the static synchronous compensator mode in an embodiment of the present application;

[0077] Figure 6 It is a schematic structural diagram of a cooperative control device in an embodiment of the present application. Detailed implementation manners

[0078] The following will describe the technical solutions in the present application in conjunction with the drawings.

[0079] The terms "first", "second", etc. in the description of the embodiments, claims and drawings of the present application are only used for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non - exclusive inclusion. For example, a method, system, product or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0080] It should be understood that in this application, "at least one (item)" means one or more, and "a plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships can exist. For example, "A and / or B" can represent: only A exists, only B exists, and both A and B exist at the same time. Among them, A and B can be singular or plural. The character " / " generally represents an "or" relationship between the front and rear associated objects. "At least one (one)" or its similar expression below refers to any combination of these items, including any combination of single item (one) or plural items (ones). For example, at least one (one) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0081] Embodiment 1

[0082] This application provides a cooperative control method for an MMC converter valve and a supercapacitor converter valve. As Figure 1 shown, the static synchronous compensator 10 may include an MMC converter valve (i.e., a modular multilevel converter valve) 1 and a supercapacitor converter valve 2.

[0083] Among them, the AC side of the MMC converter valve 1 can be connected to the AC grid G through the AC switch QFac, and the DC side of the MMC converter valve 1 can be connected to the supercapacitor converter valve 2 through the DC switches QF1dc and QF2dc. The supercapacitor converter valve 2 may include multiple branches. The multiple branches may include branch 21 and branch 22. Each branch may include a plurality of serially connected first sub-modules. The plurality of serially connected supercapacitor sub-modules include Figure 1 the first sub-module SC-SM1, the first sub-module SC-SM2,..., the first sub-module SC-SMN-1, and the first sub-module SC-SMN, a total of N first sub-modules in

[0084] Among them, the MMC converter valve 1 includes an A-phase arm, a B-phase arm, and a C-phase arm. Each phase arm includes an upper arm and a lower arm, and both the upper arm and the lower arm include a plurality of serially connected second sub-modules. For example, the A-phase arm includes the second sub-module SMa1 to the second sub-module SMa2N, the B-phase arm includes the second sub-module SMb1 to the second sub-module SMb2N, and the C-phase arm includes the second sub-module SMc1 to the second sub-module SMc2N. Figure 1 In, L is the arm reactance. U dc represents the actual value of the DC bus voltage.

[0085] As Figure 2 shown, the cooperative control method 100 includes the following steps:

[0086] Step S1: Determine the operating mode of the static synchronous compensator 10 according to the states of the DC switches QF1dc and QF2dc between the MMC converter valve 1 and the supercapacitor converter valve 2. The operating modes include the static phase modulation mode and the static synchronous compensation mode.

[0087] Step S2: In the static phase modulation mode, control the MMC converter valve 1 using the active power - frequency control method and the voltage - reactive power control method, and control the supercapacitor converter valve 2 according to the voltage command value of the DC bus where the DC switch is located.

[0088] Step S3: In the static synchronous compensation mode, control the MMC converter valve 1 using the active power - frequency control method and the voltage - reactive power control method.

[0089] In some possible implementation manners, in step S1, when the DC switches QF1dc and QF2dc are in the closed position and the supercapacitor converter valve 2 is put into operation, the operating mode of the static synchronous compensator 10 is the static phase modulation mode. When the DC switches QF1dc and QF2dc are in the open position and the supercapacitor converter valve 2 is taken out of operation, the operating mode of the static synchronous compensator 10 is the static synchronous compensation mode.

[0090] In some possible implementation manners, in steps 1 and 2, controlling the MMC converter valve using the active power - frequency control method and the voltage - reactive power control method includes:

[0091] As Figure 3 and Figure 4 shown, according to the active power command value P ref of the grid - connection point, the angular frequency command value ω ref of the static synchronous compensator 10, the reactive power command value Q ref of the grid - connection point, and the voltage command value U ref of the grid - connection point, and combining the active power - frequency control method and the voltage - reactive power control method, calculate the AC modulation voltage of the MMC converter valve 1

[0092]

[0093] Determine the circulating current modulation voltage of the MMC converter valve 1 according to the d - axis circulating current command value i cirdref and the q - axis circulating current command value i cirqref

[0094] According to the AC modulation voltage of the MMC converter valve 1 and the circulating current modulation voltage of the MMC converter valve 1, calculate the modulation voltage of the upper bridge arm and the modulation voltage of the lower bridge arm

[0095] Modulate the modulation voltage of the upper bridge arm and the modulation voltage of the lower bridge arm to obtain the first control signal CS1.

[0096] Control the MMC converter valve 1 according to the first control signal CS1.

[0097] In an example, according to the active power command value P of the grid connection point ref , the angular frequency command value ω of the static synchronous compensator 10 ref , the reactive power command value Q of the grid connection point ref and the voltage command value U of the grid connection point ref , and combining the active frequency control mode and the voltage reactive power control mode, calculate the AC modulation voltage of the MMC converter valve 1 including:[[]]

[0098] According to the active power command value P of the grid connection point ref and the angular frequency command value ω of the static synchronous compensator 10 ref , and adopt the active frequency control mode to control the actual active power P of the grid connection point e and the actual angular frequency ω of the static synchronous compensator 10 g to obtain the phase angle θ of the static synchronous compensator 10 a .

[0099] According to the reactive power command value Q of the grid connection point ref and the voltage command value U of the grid connection point ref , and adopt the voltage reactive power control mode to control the actual reactive power Q of the grid connection point e and the actual voltage U of the grid connection point m to obtain the voltage amplitude E of the static synchronous compensator 10 m .

[0100] Calculate the AC modulation voltage of the MMC converter valve 1 according to the phase angle θ a and the voltage amplitude E of the static synchronous compensator m Specifically including:[[]]

[0101]

[0101] According to the phase angle θ of the static synchronous compensator 10 a and the voltage amplitude E m determine the three-phase internal potential e of the static synchronous compensator 10 abc .

[0102] According to the three-phase internal potential e of the static synchronous compensator 10 abc and the arm reactance of the MMC converter valve 1, calculate the three-phase voltage command value u of the grid connection point abc_ref .

[0103] According to the three-phase voltage command value u of the grid connection point abc_ref , and the actual three-phase voltage of the grid connection point is controlled by adopting a double closed-loop control mode of voltage and current to obtain the AC modulation voltage of the MMC converter valve

[0104] In another example, according to the d-axis circulating current command value i cirdref and the q-axis circulating current command value i cirqref determine the circulating current modulation voltage of MMC converter valve 1 including:

[0105] According to the d-axis circulating current command value i cirdref and the q-axis circulating current command value i cirqref decouple and control the actual d-axis circulating current i cird and the actual q-axis circulating current i cirq to obtain the d-axis voltage command value u cirdref and the q-axis voltage command value u cirqref .

[0106] Perform Park inverse transformation on the d-axis voltage command value u cirdref and the q-axis voltage command value u cirqref to obtain the circulating current modulation voltage of MMC converter valve 1

[0107] Exemplarily, the modulation voltage of the upper bridge arm and the modulation voltage of the lower bridge arm respectively satisfy:

[0108]

[0109]

[0110] wherein, represents the modulation voltage of the j-phase of the upper bridge arm, represents the modulation voltage of the j-phase of the lower bridge arm. represents the AC modulation voltage of the j-phase of MMC converter valve 1; represents the circulating current modulation voltage of the j-phase of MMC converter valve 1. m dc represents the modulation voltage of the DC bus.

[0111] Among them, in the static phase modulation mode, the modulation voltage m of the DC bus dc adopts the voltage command value U of the DC bus dcref , as Figure 3 shown. In the static synchronous compensator mode, according to the voltage command value U of the DC bus dcref calculate the modulation voltage m of the DC bus dc , as Figure 4 shown.

[0112] Optionally, in step 1, the supercapacitor converter valve 2 is controlled according to the voltage command value of the DC bus where the DC switch is located, including:

[0113] Calculate the modulation voltage m of the DC bus according to the voltage command value U of the DC bus dcref of the DC bus. dc .

[0114] Modulate the modulation voltage m of the DC bus dc to obtain the second control signal CS2.

[0115] Control the supercapacitor converter valve 2 according to the second control signal CS2.

[0116] Furthermore, calculate the modulation voltage m of the DC bus according to the voltage command value U of the DC bus dcref of the DC bus, specifically including: dc As

[0117] shown, perform proportional-integral control (i.e., PI control) on the first voltage difference ΔU Figure 5 to obtain the second voltage difference ΔU dc1 of the DC bus. Among them, the first voltage difference ΔU dc2 is used to indicate the voltage difference between the voltage command value U dc1 of the DC bus and the actual voltage value U dcref of the DC bus. dc

[0118] Superimpose the second voltage difference ΔU dc2 of the DC bus on the actual voltage value U dc of the DC bus to obtain the modulation voltage m dc of the DC bus.

[0119] Embodiment 2:

[0120] Based on the same inventive concept, an embodiment of the present application further provides a coordinated control device for an MMC converter valve and a supercapacitor converter valve. Among them, the MMC converter valve and the supercapacitor converter valve can form a static synchronous compensator. The specific structure of the static synchronous compensator can refer to the above introduction and Figure 1 , which will not be elaborated in the embodiments of the present application.

[0121] As Figure 6 shown, the coordinated control device 200 may include:

[0122] A determination module 201, configured to determine the working mode of the static synchronous compensator 10 according to the states of the DC switches QF1dc and QF2dc between the MMC converter valve 1 and the supercapacitor converter valve 2. The working modes include a static phase modulation mode and a static synchronous compensation mode.

[0123] The first control module 202 is used to control the MMC converter valve 1 by using the active power - frequency control method and the voltage - reactive power control method in the static phase - modulation mode, and control the super - capacitor converter valve 2 according to the voltage command value of the DC bus where the DC switch is located.

[0124] The second control module 203 is used to control the MMC converter valve 1 by using the active power - frequency control method and the voltage - reactive power control method in the static synchronous compensator mode.

[0125] Optionally, when the DC switch QF1dc and the DC switch QF2dc are in the closed position and the super - capacitor converter valve 2 is put into operation, the determination module 201 can obtain that the operating mode of the static synchronous condenser 10 is the static phase - modulation mode. When the DC switch QF1dc and the DC switch QF2dc are in the open position and the super - capacitor converter valve 2 is taken out of operation, the determination module 201 can obtain that the operating mode of the static synchronous condenser 10 is the static synchronous compensator mode.

[0126] In a possible implementation manner, the first control module 202 or the second control module 203 is specifically used for:

[0127] As Figure 3 and Figure 4 shown, according to the active - power command value P ref of the grid - connection point, the angular - frequency command value ω ref of the static synchronous condenser 10, the reactive - power command value Q ref of the grid - connection point, and the voltage command value U ref of the grid - connection point, and combining the active - power - frequency control method and the voltage - reactive - power control method, calculate the AC modulation voltage of the MMC converter valve 1

[0128]

[0129] According to the d - axis circulating - current command value i cirdref and the q - axis circulating - current command value i cirqref to determine the circulating - current modulation voltage of the MMC converter valve 1

[0130] According to the AC modulation voltage of the MMC converter valve 1 the circulating - current modulation voltage of the MMC converter valve 1 and the modulation voltage of the DC bus to calculate the modulation voltage of the upper bridge arm of the MMC converter valve 1 and the modulation voltage of the lower bridge arm

[0131] Modulate the modulation voltage of the upper bridge arm and the modulation voltage of the lower bridge arm to obtain the first control signal CS1.

[0132] Control the MMC converter valve 1 according to the first control signal CS1.

[0133] In one example, the first control module 202 or the second control module 203 is specifically configured to:

[0134] According to the active power command value P of the grid connection point ref And the angular frequency command value ω of the static synchronous compensator 10 ref , and adopt the active frequency control method to control the actual active power P of the grid connection point e And the actual angular frequency ω of the static synchronous compensator 10 g To obtain the phase angle θ of the static synchronous compensator 10 a .

[0135] According to the reactive power command value Q of the grid connection point ref And the voltage command value U of the grid connection point ref , and adopt the voltage-reactive power control method to control the actual reactive power Q of the grid connection point e And the actual voltage U of the grid connection point m To obtain the voltage amplitude E of the static synchronous compensator 10 m .

[0136] Calculate the AC modulation voltage of the MMC converter valve 1 according to the phase angle θ a And the voltage amplitude E m Specifically includes: Specifically include:

[0137] Determine the three-phase internal potential e of the static synchronous compensator 10 according to the phase angle θ a And the voltage amplitude E m Of the static synchronous compensator 10 abc .

[0138] Calculate the three-phase voltage command value u of the grid connection point according to the three-phase internal potential e abc Of the static synchronous compensator 10 and the arm reactance of the MMC converter valve 1 abc_ref .

[0139] According to the three-phase voltage command value u abc_ref Of the grid connection point, and adopt the voltage-current double closed-loop control method to control the actual three-phase voltage of the grid connection point to obtain the AC modulation voltage of the MMC converter valve

[0140] In another example, the first control module 202 or the second control module 203 is specifically configured to:

[0141] According to the d-axis circulating current command value i cirdref And the q-axis circulating current command value i cirqref Of the static synchronous compensator 10 to control the actual d-axis circulating current icird and the actual value of the q-axis circulating current i cirq Perform decoupling control to obtain the d-axis voltage command value u cirdref and the q-axis voltage command value u cirqref .

[0142] For the d-axis voltage command value u cirdref and the q-axis voltage command value u cirqref Perform Park inverse transformation to obtain the circulating current modulation voltage of MMC converter valve 1

[0143] Exemplarily, the first control module 202 or the second control module 203 calculates the modulation voltage of the upper bridge arm and the modulation voltage of the lower bridge arm according to the following formula:

[0144]

[0145] Wherein, represents the modulation voltage of the upper bridge arm of phase j, represents the modulation voltage of the lower bridge arm of phase j; represents the AC modulation voltage of phase j of the MMC converter valve; represents the circulating current modulation voltage of phase j of the MMC converter valve; m dc represents the modulation voltage of the DC bus.

[0146] Wherein, in the static phase modulation mode, the modulation voltage m of the DC bus dc adopts the voltage command value U of the DC bus dcref , as Figure 3 shown. In the static synchronous compensator mode, according to the voltage command value U of the DC bus dcref calculate the modulation voltage m of the DC bus dc , as Figure 4 shown.

[0147] Optionally, the first control module 202 is specifically used for:

[0148] According to the voltage command value U of the DC bus dcref calculate the modulation voltage m of the DC bus dc . Modulate the modulation voltage m of the DC bus dc to obtain the second control signal CS2. Control the supercapacitor converter valve 2 according to the second control signal CS2.

[0149] According to the voltage command value U of the DC bus dcref calculate the modulation voltage m of the DC bus dc , specifically including:

[0150] As Figure 5 shown, the first voltage difference ΔU dc1Perform proportional-integral control (i.e., PI control) to obtain a second voltage difference ΔU dc2 . Among them, the first voltage difference ΔU dc1 is used to indicate the voltage command value U dcref of the DC bus and the actual voltage value U dc of the DC bus.

[0151] Superimpose the second voltage difference ΔU dc2 with the actual voltage value U dc of the DC bus to obtain the modulation voltage m dc of the DC bus.

[0152] Embodiment 3:

[0153] Based on the same inventive concept, an embodiment of the present application further provides a computer device, which includes a processor and a memory. The memory is used to store a computer program, and the computer program includes program instructions. The processor is used to execute the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, and is suitable for implementing one or more instructions. Specifically, it is suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of the collaborative control method provided in the above embodiment.

[0154] Embodiment 4:

[0155] Based on the same inventive concept, an embodiment of the present application also provides a computer-readable storage medium, specifically a computer-readable storage medium (Memory). A computer-readable storage medium is a memory device in a computer device, used to store programs and data. It can be understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and, of course, the extended storage medium supported by the computer device. The computer-readable storage medium provides a storage space, and this storage space stores the operating system of the terminal. And, in this storage space, there is also stored one or more instructions suitable for being loaded and executed by the processor. These instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The one or more instructions stored in the computer-readable storage medium can be loaded and executed by the processor to implement the steps of the collaborative control method provided in the above embodiment.

[0156] Those skilled in the art should understand that the embodiments of the application can be provided as a method, a system, or a computer program product. Therefore, the application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program codes.

[0157] The application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the application. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the function specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0158] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device implements the function in Figure 1 one flow or multiple flows and / or blocks Figure 1The functions specified in one or more boxes.

[0159] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide for implementing the steps of the functions specified in one Figure 1 one process or more processes and / or boxes Figure 1 step of the functions specified in one box or more boxes.

[0160] The above are only embodiments of the application and are not intended to limit the application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the application are included within the scope of the claims of the invention pending approval.

Claims

1. A method for coordinated control of an MMC converter valve and a supercapacitor converter valve, characterized in that: include: Determine the working mode of the static synchronous condenser according to the state of the DC switch between the MMC converter valve and the supercapacitor converter valve; wherein the working mode includes a static phase modulation mode and a static synchronous compensation mode; In the static phase modulation mode, the MMC converter valve is controlled by active frequency control and voltage reactive control, and the supercapacitor converter valve is controlled according to the voltage command value of the DC bus where the DC switch is located; In the static synchronous compensation mode, the MMC converter valve is controlled by using an active frequency control method and a voltage reactive power control method.

2. The collaborative control method according to claim 1, characterized in that: The method of controlling the MMC converter valve by using an active frequency control method and a voltage reactive power control method includes: According to the active power command value of the grid connection point, the angular frequency command value of the static synchronous condenser, the reactive power command value of the grid connection point and the voltage command value of the grid connection point, and in combination with the active frequency control mode and the voltage reactive power control mode, the AC modulation voltage of the MMC converter valve is calculated; Determining the circulating current modulation voltage of the MMC converter valve according to the d-axis circulating current command value and the q-axis circulating current command value; Calculating the modulation voltage of the upper bridge arm and the modulation voltage of the lower bridge arm in the MMC converter valve according to the AC modulation voltage of the MMC converter valve, the circulating current modulation voltage of the MMC converter valve and the modulation voltage of the DC bus; Modulating the modulation voltage of the upper bridge arm and the modulation voltage of the lower bridge arm to obtain a first control signal; The MMC converter valve is controlled according to the first control signal.

3. The collaborative control method according to claim 2, characterized in that: The calculation of the AC modulation voltage of the MMC converter valve according to the active power command value of the grid connection point, the angular frequency command value of the static synchronous condenser, the reactive power command value of the grid connection point and the voltage command value of the grid connection point, in combination with the active frequency control mode and the voltage reactive power control mode, includes: According to the active power command value of the grid connection point and the angular frequency command value of the static synchronous condenser, the active power actual value of the grid connection point and the angular frequency actual value of the static synchronous condenser are controlled by the active frequency control method to obtain the phase angle of the static synchronous condenser; According to the reactive power command value of the grid connection point and the voltage command value of the grid connection point, the actual reactive power value of the grid connection point and the actual voltage value of the grid connection point are controlled by a voltage reactive control method to obtain the voltage amplitude of the static synchronous condenser; The AC modulation voltage of the MMC converter valve is calculated according to the phase angle and voltage amplitude of the static synchronous condenser.

4. The collaborative control method according to claim 2, characterized in that: The method of determining the circulating current modulation voltage of the MMC converter valve according to the d-axis circulating current command value and the q-axis circulating current command value comprises: Decoupling control is performed on the d-axis circulating current actual value and the q-axis circulating current actual value according to the d-axis circulating current command value and the q-axis circulating current command value to obtain a d-axis voltage command value and a q-axis voltage command value; Performing a Park inverse transformation on the d-axis voltage command value and the q-axis voltage command value to obtain the circulating current modulation voltage of the MMC converter valve.

5. The collaborative control method according to claim 2, characterized in that: The modulation voltage of the upper bridge arm and the modulation voltage of the lower bridge arm respectively satisfy: in, represents the modulation voltage of the upper bridge arm j phase, represents the modulation voltage of the j-phase of the lower bridge arm; represents the j-phase AC modulation voltage of the MMC converter valve; represents the j-phase circulating current modulation voltage of the MMC converter valve; m dc represents the modulation voltage of the DC bus; in the static phase modulation mode, the modulation voltage of the DC bus adopts the voltage command value of the DC bus; in the static synchronous compensation mode, the modulation voltage of the DC bus is calculated according to the voltage command value of the DC bus.

6. The collaborative control method according to claim 1, characterized in that: The controlling the supercapacitor converter valve according to the voltage command value of the DC bus where the DC switch is located includes: Calculating a modulation voltage of the DC bus according to a voltage command value of the DC bus; modulating the modulation voltage of the DC bus to obtain a second control signal; The supercapacitor converter valve is controlled according to the second control signal.

7. The collaborative control method according to claim 5 or 6, characterized in that: The step of calculating the modulation voltage of the DC bus according to the voltage command value of the DC bus comprises: The first voltage difference is subjected to proportional-integral control to obtain a second voltage difference; wherein the first voltage difference is used to indicate a voltage difference between a voltage command value of the DC bus and an actual voltage value of the DC bus; The second voltage difference is superimposed on the actual voltage value of the DC bus to obtain a modulation voltage of the DC bus.

8. A coordinated control device for an MMC converter valve and a supercapacitor converter valve, characterized in that: include: A determination module, used to determine the working mode of the static synchronous condenser according to the state of the DC switch between the MMC converter valve and the supercapacitor converter valve; wherein the working mode includes a static phase modulation mode and a static synchronous compensation mode; A first control module is used to control the MMC converter valve in the static phase modulation mode by adopting an active frequency control mode and a voltage reactive power control mode, and to control the supercapacitor converter valve according to a voltage command value of a DC bus where the DC switch is located; The second control module is used to control the MMC converter valve in the static synchronous compensation mode by adopting an active frequency control method and a voltage reactive power control method.

9. The cooperative control device according to claim 8, characterized in that: The first control module or the second control module is specifically used for: According to the active power command value of the grid connection point, the angular frequency command value of the static synchronous condenser, the reactive power command value of the grid connection point and the voltage command value of the grid connection point, and in combination with the active frequency control mode and the voltage reactive power control mode, the AC modulation voltage of the MMC converter valve is calculated; Determining the circulating current modulation voltage of the MMC converter valve according to the d-axis circulating current command value and the q-axis circulating current command value; Calculating the modulation voltage of the upper bridge arm and the modulation voltage of the lower bridge arm in the MMC converter valve according to the AC modulation voltage of the MMC converter valve, the circulating current modulation voltage of the MMC converter valve and the modulation voltage of the DC bus; Modulating the modulation voltage of the upper bridge arm and the modulation voltage of the lower bridge arm to obtain a first control signal; The MMC converter valve is controlled according to the first control signal.

10. The cooperative control device according to claim 9, characterized in that: The first control module or the second control module is specifically used for: According to the active power command value of the grid connection point and the angular frequency command value of the static synchronous condenser, the active power actual value of the grid connection point and the angular frequency actual value of the static synchronous condenser are controlled by the active frequency control method to obtain the phase angle of the static synchronous condenser; According to the reactive power command value of the grid connection point and the voltage command value of the grid connection point, the actual reactive power value of the grid connection point and the actual voltage value of the grid connection point are controlled by a voltage reactive control method to obtain the voltage amplitude of the static synchronous condenser; The AC modulation voltage of the MMC converter valve is calculated according to the phase angle and voltage amplitude of the static synchronous condenser.

11. The cooperative control device according to claim 9, characterized in that: The first control module or the second control module is specifically used for: Decoupling control is performed on the d-axis circulating current actual value and the q-axis circulating current actual value according to the d-axis circulating current command value and the q-axis circulating current command value to obtain a d-axis voltage command value and a q-axis voltage command value; Performing a Park inverse transformation on the d-axis voltage command value and the q-axis voltage command value to obtain the circulating current modulation voltage of the MMC converter valve.

12. The cooperative control device according to claim 9, characterized in that: The first control module or the second control module calculates the modulation voltage of the upper bridge arm and the modulation voltage of the lower bridge arm according to the following formula: in, represents the modulation voltage of the upper bridge arm j phase, represents the modulation voltage of the j-phase of the lower bridge arm; represents the j-phase AC modulation voltage of the MMC converter valve; represents the j-phase circulating current modulation voltage of the MMC converter valve; m dc represents the modulation voltage of the DC bus; in the static phase modulation mode, the modulation voltage of the DC bus adopts the voltage command value of the DC bus; in the static synchronous compensation mode, the modulation voltage of the DC bus is calculated according to the voltage command value of the DC bus.

13. The cooperative control device according to claim 8, characterized in that: The first control module is specifically used for: Calculating a modulation voltage of the DC bus according to a voltage command value of the DC bus; modulating the modulation voltage of the DC bus to obtain a second control signal; The supercapacitor converter valve is controlled according to the second control signal.

14. The cooperative control device according to claim 12 or 13, characterized in that: The first control module or the second control module is specifically used for: The first voltage difference is subjected to proportional-integral control to obtain a second voltage difference; wherein the first voltage difference is used to indicate a voltage difference between a voltage command value of the DC bus and an actual voltage value of the DC bus; The second voltage difference is superimposed on the actual voltage value of the DC bus to obtain a modulation voltage of the DC bus.

15. A computer device, characterized in that: include: one or more processors; The processor is used to store one or more programs; When the one or more programs are executed by the one or more processors, the collaborative control method according to any one of claims 1 to 7 is implemented.

16. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed, the collaborative control method as described in any one of claims 1 to 7 is implemented.

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