Wind power plant voltage source type SVG and control method and device thereof

Abstract

The embodiment of the invention provides a wind power plant voltage source type SVG and a control method and device thereof. The method comprises the steps that the voltage source type SVG comprises a cascaded H-bridge inverter, an isolation type DC / DC converter, an energy storage element and a control unit; the cascaded H-bridge inverter is arranged on the direct current side of the SVG and is electrically connected with the energy storage element through the isolated DC / DC converter; the control unit comprises a stability control module which is used for adjusting an inertia coefficient and a damping coefficient when it is detected that the SVG power angle does not meet a preset stability condition, so that the SVG is converted into a deceleration state from an acceleration state until the power angle meets the stability condition. And the transient support capability of the voltage source type SVG is enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wind power control, in particular to a wind farm voltage source SVG and a control method and device thereof. BACKGROUND

[0002] Under the background of large-scale access of new energy to power grid, as a kind of reactive power compensation device, static var generator (SVG) has been widely used in wind power, photovoltaic and other new energy stations because it can provide voltage support for power system and enhance system stability. The traditional SVG adopts grid-connected control strategy, its operation mode is similar to current source, it depends on grid voltage to provide reference, its transient response speed is slow, and it is easy to cause stability problem in weak grid environment, which limits its support ability in high penetration rate new energy system.

[0003] In contrast, the voltage source SVG with grid-forming control has similar operating characteristics with synchronous phase modifier, it can maintain the internal potential amplitude unchanged at the moment of fault occurrence, quickly respond to output current, and has obvious dynamic advantage. The voltage source SVG behaves as a voltage source, not only has fast current response ability, but also can provide stronger reactive power support in weak grid, realizes "true synchronous compensation", and effectively alleviates system voltage fluctuation and oscillation problem. At present, the voltage source SVG based on grid-forming control has been successfully put into operation in large wind farm, showing good application prospect.

[0004] For the transient support ability of voltage source SVG, existing research mainly focuses on two aspects: one is to dynamically adjust the active power reference value to maintain the power angle in the stable interval; the other is to optimize the controller structure or parameters, such as introducing frequency deviation compensation, virtual damping gain, dynamic inertia adjustment and other means to improve the transient response of the synchronous ability. However, both of these two methods have obvious limitations: the former may reduce the active power transmission capacity of the converter, and the latter can improve the transient response, but it is difficult to completely avoid the loss of synchronization of the converter under certain disturbance, and it cannot realize automatic resynchronization after instability. SUMMARY

[0005] In view of the problems in the prior art, the present application provides a wind farm voltage source SVG and a control method and device thereof, which can avoid the transient synchronization instability phenomenon of the voltage source SVG and enhance the transient support ability of the voltage source SVG.

[0006] In order to solve at least one of the above problems, the present application provides the following technical solutions:

[0007] The voltage source SVG comprises a cascaded H-bridge inverter, an isolation type DC / DC converter, an energy storage element and a control unit.

[0008] The cascade H-bridge inverter is arranged at the DC side of the SVG and is electrically connected with the energy storage element through the isolation type DC / DC converter.

[0009] The control unit comprises a stable control module, which is configured to adjust the inertia coefficient and the damping coefficient when it is detected that the SVG power angle does not satisfy the preset stable condition, so as to make the SVG change from the acceleration state to the deceleration state until the power angle satisfies the stable condition.

[0010] According to any one of the embodiments of the present application, the stable control module is configured to adjust the inertia coefficient and the damping coefficient when it is detected that the SVG power angle does not satisfy the preset stable condition, so as to make the SVG change from the acceleration state to the deceleration state until the power angle satisfies the stable condition.

[0011] In the case that the power angle change speed, the active power change rate and the power angle acceleration are all greater than zero, the inertia coefficient value and the damping coefficient value are switched to their opposites.

[0012] According to any one of the embodiments of the present application, the control unit further comprises an active control loop, a reactive control loop and an inner loop.

[0013] The active control loop is configured to construct a power synchronization control structure according to the active power deviation between the SVG output power and the reference power, and to obtain a virtual potential phase angle between the SVG and the power grid for phase synchronization control.

[0014] The reactive control loop is configured to generate a virtual potential amplitude according to the SVG output reactive power and the reactive reference value under the reactive voltage droop control.

[0015] The inner loop comprises a voltage control loop and a current control loop.

[0016] The voltage control loop is configured to determine a current instruction component according to the virtual potential amplitude reference and the actual SVG output voltage.

[0017] The current control loop is configured to perform coordinate transformation on the current instruction component, and to control the SVG output three-phase alternating current to be consistent with the target instruction through current limiting control and current closed-loop adjustment.

[0018] According to any one of the embodiments of the present application, the control unit further comprises a reference value switching module, which is configured to:

[0019] When the state of charge of the SVG DC side is higher than the upper threshold, the active reference value is set to zero.

[0020] When the state of charge of the SVG DC side is lower than the lower threshold, the active reference value is set to one.

[0021] According to any one of the embodiments of the present application, the control unit further comprises a capacitor balancing control module, which is configured to:

[0022] The voltage difference of each sub-module is determined according to the DC voltage detection result of each sub-module in the cascade H-bridge inverter, and the output of the sub-modules in the same bridge arm and the sub-modules between different bridge arms is balanced and adjusted respectively.

[0023] According to a second aspect of the embodiment of the present application, the present application provides a voltage source type SVG control method, comprising:

[0024] The power angle change speed, the power angle change acceleration and the active power change rate of the SVG are determined according to the power angle between the voltage source type SVG and the power grid;

[0025] It is determined whether the power angle meets a preset stability condition according to the numerical values of the power angle change speed, the power angle change acceleration and the active power change rate;

[0026] In response to the power angle not meeting the stability condition, the inertia coefficient value and the damping coefficient value of the current SVG are switched to their opposite numbers.

[0027] According to any embodiment of the present application, the stability condition represents that the power angle change speed, the active power change rate and the power angle acceleration are all greater than zero.

[0028] According to a third aspect of the embodiment of the present application, the present application provides a voltage source type SVG control device, comprising:

[0029] A parameter acquisition unit is configured to determine the power angle change speed, the power angle change acceleration and the active power change rate of the SVG according to the power angle between the voltage source type SVG and the power grid;

[0030] A condition judgment unit is configured to determine whether the power angle meets a preset stability condition according to the numerical values of the power angle change speed, the power angle change acceleration and the active power change rate;

[0031] A stability control unit is configured to switch the inertia coefficient value and the damping coefficient value of the current SVG to their opposite numbers in response to the power angle not meeting the stability condition.

[0032] The stability condition represents that the power angle change speed, the active power change rate and the power angle acceleration are all greater than zero.

[0033] According to a fourth aspect of the embodiment of the present application, the present application provides an electronic device, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the voltage source type SVG control method when executing the program.

[0034] According to a fifth aspect of the embodiments of the present application, the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the steps of the voltage source SVG control method.

[0035] According to a sixth aspect of the embodiments of the present application, the present application provides a computer program product, which comprises computer programs / instructions, and the computer programs / instructions are executed by a processor to implement the steps of the voltage source SVG control method.

[0036] According to the above technical solution, the present application provides a wind farm voltage source SVG and a control method and device thereof. The voltage source SVG comprises a cascaded H-bridge inverter, an isolated DC / DC converter, an energy storage element, and a control unit. The cascaded H-bridge inverter is arranged on the SVG DC side and is electrically connected to the energy storage element through the isolated DC / DC converter. The control unit comprises a stability control module, which is used to adjust the inertia coefficient and the damping coefficient when it is detected that the SVG power angle does not satisfy the preset stability condition, so as to make the SVG change from the acceleration state to the deceleration state until the power angle satisfies the stability condition. The present application can avoid the transient synchronous instability phenomenon of the voltage source SVG and enhance the transient support capability of the voltage source SVG. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0038] Figure 1 The voltage source SVG topological structure in the embodiments of the present application is shown in the figure.

[0039] Figure 2 The overall control strategy of the voltage source SVG in the embodiments of the present application is shown in the figure.

[0040] Figure 3 The voltage source SVG grid-connected system topological structure in the embodiments of the present application is shown in the figure.

[0041] Figure 4 The voltage source SVG control method in the embodiments of the present application is shown in the figure.

[0042] Figure 5 The voltage source SVG mode adaptive synchronous control in the embodiments of the present application is shown in the figure.

[0043] Figure 6A schematic diagram of adaptive switching logic of a voltage source SVG in the embodiment of the present application;

[0044] Figure 7 A simulation waveform diagram when the adaptive synchronization strategy is not adopted in the embodiment of the present application;

[0045] Figure 8 A simulation waveform diagram under the adaptive synchronization strategy in the embodiment of the present application;

[0046] Figure 9 A schematic diagram of damping coefficient and inertia coefficient of a voltage source SVG in the embodiment of the present application;

[0047] Figure 10 A schematic diagram of a voltage source SVG control device in the embodiment of the present application;

[0048] Figure 11 A structural schematic diagram of an electronic device in the embodiment of the present application. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0050] The acquisition, storage, use, processing and the like of data in the technical scheme of the present application comply with relevant provisions of laws and regulations.

[0051] The present application provides a wind farm voltage source SVG and a control method and device thereof, which avoids transient synchronization instability phenomenon of the voltage source SVG and enhances transient support capability of the voltage source SVG.

[0052] In order to avoid transient synchronization instability phenomenon of the voltage source SVG and enhance transient support capability of the voltage source SVG, the present application provides an embodiment of a voltage source SVG, which comprises a cascaded H-bridge inverter, an isolation type DC / DC converter, an energy storage element and a control unit;

[0053] The cascaded H-bridge inverter is arranged at the SVG DC side and is electrically connected with the energy storage element through the isolation type DC / DC converter;

[0054] The energy storage element comprises a super capacitor;

[0055] The control unit comprises a stability control module, configured to adjust the inertia coefficient and the damping coefficient when it is detected that the SVG power angle does not satisfy the preset stability condition, so as to make the SVG change from an acceleration state to a deceleration state until the power angle satisfies the stability condition.

[0056] In the formula, referring to Figure 1 The SVG adopts a cascaded H-bridge type topology structure, and each phase bridge arm comprises N sub-modules. The DC side of the SVG is connected with the energy storage element through an isolation type DC / DC converter. The electrical connection between the DC bus of the SVG and the energy storage element is realized through the isolation type DC / DC converter, so that the insulation performance and operation safety of the device can be effectively ensured.

[0057] In the application, the super capacitor is used as the energy storage element. Compared with the traditional chemical battery, the super capacitor has a significant improvement in the power density index and has a large instantaneous large current carrying capacity.

[0058] The traditional SVG needs to provide a certain active power from the grid side to maintain its stable operation in the operation process. The access of the energy storage element can effectively maintain the constant SVG DC bus voltage, so that the SVG does not need to absorb the active power from the grid side, thereby significantly enhancing the stability of the SVG. In addition, the SVG with the energy storage element also has the ability to provide active power compensation to the grid, so as to realize the bidirectional power flow when the system needs.

[0059] In an optional embodiment, the stability control module is configured to adjust the inertia coefficient and the damping coefficient when it is detected that the SVG power angle does not satisfy the preset stability condition, so as to make the SVG change from an acceleration state to a deceleration state until the power angle satisfies the stability condition.

[0060] In the case that the power angle change rate, the active power change rate and the power angle acceleration are all greater than zero, the inertia coefficient value and the damping coefficient value are switched to their opposite numbers.

[0061] For example, the stability control module is configured to monitor the power angle state of the SVG in real time during the operation of the SVG, and judge whether there is a transient instability risk. When the system is disturbed and the power angle change rate, the active power change rate and the power angle acceleration of the SVG are all positive, it indicates that the SVG is in a continuous acceleration and instability state, and the stability control module judges that the current does not satisfy the set stability condition. At this time, the module immediately switches the signs of the inertia coefficient and the damping coefficient, so that the positive feedback dynamics that originally promote the SVG to accelerate is changed to negative feedback, so as to make the SVG change from an acceleration state to a deceleration state, thereby forcing the SVG power angle to fall back to the stable equilibrium point. The control mechanism ensures that the SVG can automatically restore synchronous operation after passing through the unstable equilibrium point, enhances the transient support capability and maintains the system stability.

[0062] In an alternative embodiment, the control unit further comprises an active control loop, a reactive control loop and an inner loop;

[0063] The active control loop is configured to construct a power synchronization control structure according to an active power deviation between an SVG output power and a reference power, and to obtain a virtual internal potential phase angle between the SVG and the power grid for phase synchronization control;

[0064] The reactive control loop is configured to generate a virtual internal potential amplitude according to a reactive power output by the SVG and a reactive reference value under a reactive voltage droop control;

[0065] The inner loop comprises a voltage control loop and a current control loop:

[0066] The voltage control loop is configured to determine a current instruction component according to a virtual internal potential amplitude reference and an actual output voltage of the SVG;

[0067] The current control loop is configured to coordinate transform the current instruction component, and to control three-phase alternating currents output by the SVG to be consistent with target instructions through current closed-loop regulation and current limiting control.

[0068] The overall control strategy of the voltage source SVG is composed of the active control loop, the reactive control loop and the inner loop, Figure 2 The overall control strategy of the voltage source SVG is composed of the active control loop, the reactive control loop and the inner loop,

[0069] The active control loop adopts power synchronization control to realize synchronization with the power grid by simulating a motion equation of a synchronous phase modifier,

[0070] The reactive control loop adopts reactive voltage droop control to generate a virtual internal potential amplitude reference,

[0071] The inner loop adopts voltage-current double closed loop control to regulate U abc to track a reference voltage.

[0072] Figure 2 In the equation, J and D are respectively an inertia coefficient and a damping coefficient of the voltage source SVG; P S and Q S are respectively an active power output by the voltage source SVG and a reactive power output by the voltage source SVG; P ref and Q ref are respectively an active power reference value and a reactive power reference value; k q is a reactive droop coefficient; E and θ are respectively a virtual internal potential amplitude and a phase angle of the voltage source SVG; ω is an angular frequency of the voltage source SVG; L is a total connection reactance between the SVG and the power grid; u dc is a DC side voltage of a voltage source SVG sub-module; u abc is a three-phase voltage output by the voltage source SVG; i abc is a three-phase current output by the voltage source SVG.

[0073] The active power control loop is used to construct a power synchronization control structure based on the active power deviation between the SVG output power and the reference power, and to obtain the virtual potential phase angle between the SVG and the power grid for phase synchronization control.

[0074] Located in the "Active Power Control Loop" module in the lower left corner of the diagram, the SVG outputs active power P. S Compared with reference value P ref The difference is input into a subtractor to form a power bias, which is then processed by an "inertia-damping structure" (1 / J). s +D) generates the angular frequency increment Δω, which is then integrator 1 / s to obtain the phase angle θ, i.e., the virtual potential phase angle of the SVG, and is finally used for phase synchronization with the power grid.

[0075] The reactive power control loop is used to generate a virtual potential amplitude in reactive voltage droop control based on the reactive power output of the SVG and the reactive power reference value. Corresponding to the "Reactive Power Control Loop" module in the diagram, the reactive power Q of the SVG... S Compared with reference value Q ref The deviation is measured by the droop coefficient k q After adjustment, the output virtual potential amplitude E is used as the reference input in the voltage control loop and coordinate transformation module.

[0076] The inner loop includes a voltage control loop and a current control loop:

[0077] The voltage control loop is used to determine the current command component based on the virtual potential amplitude reference and the actual output voltage of the SVG; this corresponds to the "Voltage Control" section in the diagram. The voltage control loop is input to the voltage deviation, i.e., the potential amplitude E and the three-phase voltage u. d ,u q The difference is used to output the current command i via the proportional-differential circuit G / (1+sT). dref i qref .

[0078] The current control loop is used to transform the coordinates of the current command components and control the three-phase AC current output by the SVG to be consistent with the target command through current limiting control and current closed-loop regulation.

[0079] See the "Current Decoupling Control" module in the diagram. Current command i dref i qref First, the current amplitude is limited by a current limiting circuit. Then, the current is fed into a PI regulator and decoupling compensation (including inductor current compensation ωL) to control the target voltage u. d ,u q Then after d q The coordinate transformation to abc generates a three-phase control signal input to the inverter, controlling the three-phase output current i. abc .

[0080] In an optional embodiment, the control unit further includes a reference value switching module, used for:

[0081] When the DC-side state of charge of the SVG is higher than the upper limit threshold, the active power reference value will be set to zero.

[0082] When the DC-side state of charge of the SVG is below the lower threshold, the active power reference value is set to one.

[0083] See Figure 2 The SOC computing module uses DC-side voltage u sc The input represents a real-time estimation of the state of charge (SOC) of the supercapacitor energy storage unit.

[0084] When the estimation result satisfies SOC>80%, the reference value switching logic output control signal will change the active power reference value P. ref Set to 0;

[0085] When the estimation result satisfies SOC < 20%, the output control signal will P ref Set to 1.

[0086] This logic dynamically assigns reference values ​​to the active power control loop input based on the energy storage state of charge, enabling the system to intelligently adjust whether to participate in power output according to the supercapacitor's charge level.

[0087] In an optional embodiment, the control unit further includes a capacitor equalization control module, used for:

[0088] The voltage difference between each sub-module is determined based on the DC voltage detection results of each sub-module in the cascaded H-bridge inverter, and the output of the sub-modules within the same bridge arm and between different bridge arms are balanced and adjusted respectively.

[0089] Combination Figure 2 It is understood that the control unit collects the DC voltage of each submodule in the cascaded H-bridge inverter, determines the voltage difference between submodules, and performs voltage balancing adjustment accordingly. When a voltage inconsistency is detected between submodules within the same phase arm, the control system adjusts the drive signal to achieve dynamic voltage balance within the same arm. Simultaneously, if a deviation in the average voltage between the three phase arms is detected, the control system will also coordinate and adjust the phase-to-phase voltage based on the phase-to-phase voltage difference, thereby ensuring consistent output across all arms and guaranteeing stable operation of each submodule under balanced conditions.

[0090] The topology diagram of the grid-connected system of a voltage source type SVG connected to a wind farm is as follows: Figure 3The voltage source type SVG is connected in parallel with the wind power station on the same bus, and is connected to the power grid through a 35 / 220kV transformer. The power generated by the wind power station is sent to the AC power grid through a single-circuit line and a double-circuit line.

[0091] In order to avoid transient synchronous instability of the voltage source type SVG and enhance the transient support capability of the voltage source type SVG, an embodiment of a voltage source type SVG control method is provided, which is shown in Figure 4 , and specifically includes the following contents:

[0092] Step S101: determining the power angle change speed, power angle change acceleration and active power change rate of the SVG according to the power angle between the voltage source type SVG and the power grid;

[0093] Step S102: determining whether the power angle meets the preset stability condition according to the values of the power angle change speed, power angle change acceleration and active power change rate;

[0094] Step S103: switching the inertia coefficient value and the damping coefficient value of the current SVG to their opposites in response to the power angle not meeting the stability condition.

[0095] For example, the stability condition indicates that the power angle change speed, the active power change rate and the power angle acceleration are all greater than zero.

[0096] After the voltage source type SVG is connected to the wind power station, there is a risk of transient synchronous instability of the voltage source type SVG due to the influence of the output of the wind power station. If the SVG power angle exceeds the unstable equilibrium point in the dynamic process of the power angle, it will start to accelerate and eventually lose synchronization with the system, which will seriously affect the transient support capability of the voltage source type SVG. The present application adjusts and adaptively switches the inertia and damping coefficients by detecting whether the power angle of the voltage source type SVG exceeds the unstable equilibrium point, so as to improve the transient support capability of the voltage source type SVG.

[0097] Only when the power angle of the voltage source type SVG exceeds the unstable equilibrium point, the three variables Δω, dΔω / dt and dΔP / dt meet the condition of being greater than zero at the same time, so the positive and negative of the three key variables Δω, dΔω / dt and dΔP / dt can be used to judge whether the power angle of the voltage source type SVG exceeds the unstable equilibrium point. The criterion for adaptive switching adopted by the present application is:

[0098]

[0099] According to the power angle dynamic equation of the power synchronization control, the increase and decrease of the delta omega can be flexibly controlled by changing the positive and negative of the inertia coefficient J and the damping coefficient D, so that the acceleration and deceleration of the voltage source SVG is completely controllable. The idea of the adaptive synchronization strategy proposed in the application is to make the voltage source SVG change from acceleration to deceleration by changing the inertia coefficient J and the damping coefficient D of the voltage source SVG after the power angle crosses the unstable equilibrium point, so as to force the SVG to return to the stable equilibrium point, thereby avoiding the transient synchronization instability of the voltage source SVG. The inertia and damping coefficient coordinated adaptive synchronization strategy adopted in the application is summarized as follows:

[0100] (1) When the power angle of the voltage source SVG does not cross the unstable equilibrium point, the inertia coefficient J1 and the damping coefficient D1 of the voltage source SVG are:

[0101] J1=J,D1=D (2)

[0102] (2) When the power angle of the voltage source SVG crosses the unstable equilibrium point, the inertia coefficient J2 and the damping coefficient D2 of the voltage source SVG are:

[0103] J2=-J,D2=-D (3)

[0104] The mode adaptive synchronization control block diagram is shown in Figure 5 .

[0105] According to the above strategy, the inertia coefficient and the damping coefficient of the voltage source SVG are designed, that is, the voltage source SVG can quickly recover to a new stable equilibrium point in the transient process, and keep synchronous and stable operation with the system. Figure 6 The adaptive switching logic diagram is shown in

[0106] From the above description, it can be seen that the voltage source SVG control method provided by the embodiment of the application can avoid the transient synchronization instability phenomenon of the voltage source SVG, and enhance the transient support capability of the voltage source SVG.

[0107] In order to further illustrate the present application, the effectiveness of the voltage source SVG transient support capability improvement method proposed in the application is verified in the PSCAD / EMTDC simulation platform. Figure 7 The time domain simulation waveform diagram when the adaptive synchronization strategy is not used is shown in the figure, from which it can be seen that under the conventional control, when the active power of the wind power station is large, after the fault occurs, the voltage source SVG experiences first deceleration, then acceleration, and then deceleration again, and in the last deceleration stage, since the SVG has not reduced to the synchronous speed when reaching the unstable equilibrium point, the power angle crosses the unstable equilibrium point, and finally loses synchronization with the system. This will seriously affect the safe and stable operation of the wind power sending system. Figure 8The time domain simulation waveform diagram after the adaptive synchronous stability enhancement method is adopted. As can be seen from the figure, after the adaptive synchronous stability enhancement method is adopted, when the voltage source type SVG power angle crosses the unstable equilibrium point, the inertia coefficient and the damping coefficient of the voltage source type SVG can be changed to force the voltage source type SVG to continue to decelerate, and finally return to a new stable equilibrium point and keep synchronization with the system. Through simulation analysis, it is further verified that the adaptive control strategy can greatly enhance the transient support performance of the voltage source type SVG, and is also conducive to further improving the wind power transmission capacity.

[0108] Figure 9 The damping coefficient and inertia coefficient of the voltage source type SVG before and after the adaptive synchronization strategy is adopted. As can be seen from the figure, when the fault occurs, the adaptive switching detection detects that the power angle of the voltage source type SVG crosses the unstable equilibrium point at 1.28s. At this time, the adaptive synchronization strategy is put into operation, the damping coefficient of the voltage source type SVG changes from 25 to-25, and the inertia coefficient changes from 0.05 to-0.05, forcing the SVG to keep deceleration until 1.57s when it returns to the unstable equilibrium point, and the adaptive synchronization strategy exits operation. Finally, the voltage source type SVG reaches a new stable operating state and keeps synchronization with the system. The simulation results verify the effectiveness of the proposed voltage source type SVG transient support capacity enhancement method, which can promote the resynchronization of the voltage source type SVG after instability and greatly improve the support effect of the voltage source type SVG for the wind power station.

[0109] In order to avoid the transient synchronization instability phenomenon of the voltage source type SVG and enhance the transient support capacity of the voltage source type SVG, an embodiment of a voltage source type SVG control device for implementing all or part of the contents of the voltage source type SVG control method is provided, as shown in Figure 10 , which specifically includes the following contents:

[0110] The parameter acquisition unit 1101 is configured to determine the power angle change speed, power angle change acceleration and active power change rate of the SVG according to the power angle between the voltage source type SVG and the power grid.

[0111] The condition judgment unit 1102 is configured to determine whether the power angle meets the preset stability condition according to the values of the power angle change speed, power angle change acceleration and active power change rate.

[0112] The stability control unit 1103 is configured to switch the inertia coefficient value and the damping coefficient value of the current SVG to their opposites in response to the power angle not meeting the stability condition.

[0113] The stability condition represents that the power angle change speed, the active power change rate and the power angle acceleration are all greater than zero.

[0114] From the above description, the voltage source type SVG control device provided by the embodiment of the application can avoid transient synchronous instability of the voltage source type SVG and enhance the transient support capability of the voltage source type SVG.

[0115] From the hardware aspect, in order to avoid transient synchronous instability of the voltage source type SVG and enhance the transient support capability of the voltage source type SVG, the embodiment of the electronic device for implementing all or part of the contents of the voltage source type SVG control method is provided, and the electronic device specifically includes the following contents:

[0116] a processor, a memory, a communications interface and a bus; wherein the processor, the memory and the communications interface complete mutual communication through the bus; the communications interface is used for realizing information transmission between the voltage source type SVG control device and a core business system, a user terminal and a related database and other related devices; the logic controller can be a desktop computer, a tablet computer, a mobile terminal and the like, and the embodiment is not limited thereto. In the embodiment, the logic controller can be implemented by referring to the embodiment of the voltage source type SVG control method and the embodiment of the voltage source type SVG control device, the contents of which are incorporated herein, and the repeated parts will not be described herein.

[0117] It can be understood that the user terminal can include a smart phone, a tablet electronic device, a network set-top box, a portable computer, a desktop computer, a personal digital assistant (PDA), a vehicle-mounted device, a smart wearable device and the like. The smart wearable device can include smart glasses, a smart watch, a smart bracelet and the like.

[0118] In actual application, part of the voltage source type SVG control method can be executed on the electronic device as described above, or all operations can be completed in the client device. Specifically, the selection can be made according to the processing capability of the client device and the limitation of the user use scenario, and the like. The application is not limited thereto. If all operations are completed in the client device, the client device can further include a processor.

[0119] The client device described above can have a communications module (i.e. a communications unit) and can be communicatively connected with a remote server to realize data transmission with the server. The server can include a server of a task scheduling center side, and can further include a server of an intermediate platform in other implementation scenarios, such as a server of a third-party server platform communicatively connected with the server of the task scheduling center. The server can include a single computer device, a server cluster composed of multiple servers or a server structure of a distributed device.

[0120] Figure 11 This is a schematic block diagram illustrating the system configuration of the electronic device 9600 according to an embodiment of this application. Figure 11 As shown, the electronic device 9600 may include a central processing unit 9100 and a memory 9140; the memory 9140 is coupled to the central processing unit 9100. It is worth noting that... Figure 11 This is an example; other types of structures can also be used to supplement or replace this structure to achieve telecommunications functions or other functions.

[0121] In one embodiment, the voltage source type SVG control method functionality can be integrated into the central processing unit 9100. The central processing unit 9100 can be configured to perform the following control:

[0122] Step S101: Determine the power angle change rate, power angle change acceleration, and active power change rate of the SVG based on the power angle between the voltage source type SVG and the power grid;

[0123] Step S102: Determine whether the power angle meets the preset stability condition based on the values ​​of the power angle change rate, power angle change acceleration, and active power change rate.

[0124] Step S103: In response to the fact that the power angle does not meet the stability condition, the inertia coefficient value and damping coefficient value of the current SVG are switched to their opposite values.

[0125] As can be seen from the above description, the electronic device provided in this application embodiment avoids transient synchronization instability of voltage source type SVG and enhances the transient support capability of voltage source type SVG.

[0126] In another embodiment, the voltage source type SVG control device can be configured separately from the central processing unit 9100. For example, the voltage source type SVG control device can be configured as a chip connected to the central processing unit 9100, and the voltage source type SVG control method function can be implemented through the control of the central processing unit.

[0127] like Figure 11 As shown, the electronic device 9600 may further include: a communication module 9110, an input unit 9120, an audio processor 9130, a display 9160, and a power supply 9170. It is worth noting that the electronic device 9600 does not necessarily need to include these components. Figure 11 All components shown; in addition, the electronic device 9600 may also include Figure 11 For components not shown, please refer to existing technologies.

[0128] like Figure 11As shown, the central processing unit 9100, which is sometimes also referred to as a controller or operation control, can include a microprocessor or other processor device and / or logic device, which receives input and controls the operation of the various components of the electronic device 9600.

[0129] The memory 9140, for example, can be one or more of a buffer, a flash memory, a hard drive, a removable media, a volatile memory, a non-volatile memory, or other suitable device. Information relating to failures can be stored, and in addition, programs for executing the information can be stored. The central processing unit 9100 can execute the programs stored in the memory 9140 to achieve information storage or processing, etc.

[0130] The input unit 9120 provides input to the central processing unit 9100. The input unit 9120 is, for example, a key or touch input device. The power supply 9170 is used to provide power to the electronic device 9600. The display 9160 is used to display display objects such as images and text. The display can be, for example, an LCD display, but is not limited thereto.

[0131] The memory 9140 can be a solid state memory such as a read only memory (ROM), a random access memory (RAM), a SIM card, etc. It can also be a memory that retains information even when power is off, can be selectively erased, and is provided with more data, examples of which are sometimes referred to as EPROM, etc. The memory 9140 can also be some other type of device. The memory 9140 includes a buffer memory 9141 (sometimes referred to as a buffer). The memory 9140 can include an application / function storage section 9142 for storing application programs and function programs or for storing a flow for executing the operation of the electronic device 9600 by the central processing unit 9100.

[0132] The memory 9140 can also include a data storage section 9143 for storing data such as contacts, digital data, pictures, sounds, and / or any other data used by the electronic device. A driver program storage section 9144 of the memory 9140 can include various driver programs of the electronic device for communication functions and / or for executing other functions of the electronic device such as a messaging application, an address book application, etc.

[0133] The communication module 9110 is a transmitter / receiver that transmits and receives signals via an antenna 9111. The communication module (transmitter / receiver) 9110 is coupled to the central processing unit 9100 to provide input signals and receive output signals, which can be the same as in the case of a conventional mobile communication terminal.

[0134] Based on different communication technologies, multiple communication modules 9110, such as a cellular network module, a Bluetooth module, and / or a wireless local area network module, etc., can be provided in the same electronic device. The communication module (transmitter / receiver) 9110 is also coupled to a speaker 9131 and a microphone 9132 via an audio processor 9130 to provide audio output via the speaker 9131 and to receive audio input from the microphone 9132, thereby enabling the usual telecommunication functions. The audio processor 9130 can include any suitable buffers, decoders, amplifiers, etc. In addition, the audio processor 9130 is also coupled to the central processor 9100, thereby enabling the recording of sounds on the local device via the microphone 9132 and enabling the playing of stored sounds via the speaker 9131.

[0135] The embodiment of the present application further provides a computer readable storage medium capable of implementing all steps of the voltage source SVG control method with the execution subject being a server or a client in the above-mentioned embodiment. The computer program is stored on the computer readable storage medium. When the processor executes the computer program, all steps of the voltage source SVG control method with the execution subject being a server or a client in the above-mentioned embodiment are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0136] Step S101: determining the power angle change speed, the power angle change acceleration, and the active power change rate of the SVG according to the power angle between the voltage source SVG and the power grid.

[0137] Step S102: determining whether the power angle meets the preset stability condition according to the numerical values of the power angle change speed, the power angle change acceleration, and the active power change rate.

[0138] Step S103: switching the inertia coefficient value and the damping coefficient value of the current SVG to their opposites in response to the power angle not meeting the stability condition.

[0139] As known from the above description, the computer readable storage medium provided by the embodiment of the present application avoids the transient synchronous instability phenomenon of the voltage source SVG and enhances the transient support capability of the voltage source SVG.

[0140] The embodiment of the present application further provides a computer program product capable of implementing all steps of the voltage source SVG control method with the execution subject being a server or a client in the above-mentioned embodiment. The computer program / instruction is executed by the processor to implement the steps of the voltage source SVG control method. For example, the computer program / instruction implements the following steps:

[0141] Step S101: determining a power angle change speed, a power angle change acceleration and an active power change rate of the SVG according to a power angle between the voltage source SVG and the power grid;

[0142] Step S102: determining whether the power angle meets a preset stability condition according to values of the power angle change speed, the power angle change acceleration and the active power change rate;

[0143] Step S103: switching inertia coefficient values and damping coefficient values of the current SVG to their opposites in response to the power angle not meeting the stability condition.

[0144] From the above description, it can be seen that the computer program product provided by the embodiment of the present application avoids the transient synchronous instability phenomenon of the voltage source SVG, and enhances the transient support capability of the voltage source SVG.

[0145] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, device, or computer program product. Therefore, the present application can adopt a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt a computer program product in the form of being implemented on one or more computer usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program codes.

[0146] The present application is described with reference to flowcharts and / or block diagrams of the method, device (apparatus) and computer program product according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus produce a device implemented in the flowcharts and / or block diagrams. Figure 1 The function specified in one or more flows and / or blocks Figure 1 The device that implements the function specified in one or more flows and / or blocks.

[0147] These computer program instructions can also be stored in a computer readable storage medium capable of guiding the computer or other programmable data processing apparatus to work in a specific manner, so that the instructions stored in the computer readable storage medium produce a product including instruction devices, which implement the flowcharts and / or block diagrams. Figure 1 The function specified in one or more flows and / or blocks Figure 1 The device that implements the function specified in one or more flows and / or blocks.

[0148] These computer program instructions can also be loaded into a computer or other programmable data processing devices, so that a series of operational steps are generated to realize the computer-implemented processes, and the instructions executed on the computer or other programmable devices provide a process for implementing the functions specified in the flowchart Figure 1 one flow or multiple flows and / or the functions specified in the block Figure 1 Figure 1 one flow or multiple flows and / or the functions specified in the block

[0149] The principles and implementation manners of the present application are described in the specific embodiments. The above embodiment descriptions are only used to help understand the method and core idea of the present application; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manners and application ranges will be changed, and the above descriptions should not be understood as limitations on the present application.

Claims

1. A wind farm voltage source type SVG, characterized in that, The voltage source type SVG includes a cascaded H-bridge inverter, an isolated DC / DC converter, an energy storage element, and a control unit; The cascaded H-bridge inverter is located on the DC side of the SVG and is electrically connected to the energy storage element through the isolated DC / DC converter. The control unit includes a stability control module, which adjusts the inertia coefficient and damping coefficient when the SVG power angle is detected to not meet the preset stability conditions, so that the SVG changes from an acceleration state to a deceleration state until the power angle meets the stability conditions.

2. The wind farm voltage source type SVG according to claim 1, characterized in that, When the stability control module detects that the SVG's power angle does not meet the preset stability condition, it adjusts the inertia coefficient and damping coefficient to cause the SVG to change from an acceleration state to a deceleration state until the power angle meets the stability condition. This is used to: When the rate of change of the power angle, the rate of change of the active power, and the power angle acceleration are all greater than zero, the values ​​of the inertia coefficient and the damping coefficient are switched to their opposites.

3. The wind farm voltage source type SVG according to claim 1, characterized in that, The control unit also includes an active power control loop, a reactive power control loop, and an inner loop; The active power control loop is used to construct a power synchronization control structure based on the active power deviation between the SVG output power and the reference power, and to obtain the virtual potential phase angle between the SVG and the power grid for phase synchronization control. The reactive power control loop is used to generate a virtual potential amplitude based on the reactive power output by the SVG and the reactive power reference value under reactive voltage droop control. The inner loop includes a voltage control loop and a current control loop: The voltage control loop is used to determine the current command component based on the virtual potential amplitude reference and the actual output voltage of the SVG. The current control loop is used to transform the coordinates of the current command components and control the three-phase AC current output by the SVG to be consistent with the target command through current limiting control and current closed-loop regulation.

4. The wind farm voltage source type SVG according to claim 1, characterized in that, The control unit further includes a reference value switching module, used for: When the DC-side state of charge of the SVG is higher than the upper limit threshold, the active power reference value will be set to zero. When the DC-side state of charge of the SVG is below the lower threshold, the active power reference value is set to one.

5. The wind farm voltage source type SVG according to claim 1, characterized in that, The control unit also includes a capacitor equalization control module, used for: The voltage difference between each sub-module is determined based on the DC voltage detection results of each sub-module in the cascaded H-bridge inverter, and the output of the sub-modules within the same bridge arm and between different bridge arms are balanced and adjusted respectively.

6. A voltage source type SVG control method, characterized in that, The control unit applied to the wind farm voltage source type SVG of claim 1, the method comprising: The rate of change of the SVG's power angle, the acceleration of the power angle change, and the rate of change of active power are determined based on the power angle between the voltage source type SVG and the power grid. The power angle is determined to meet the preset stability condition based on the values ​​of the power angle change rate, the power angle change acceleration, and the active power change rate. In response to the fact that the power angle does not meet the stability condition, the current inertia coefficient and damping coefficient values ​​of the SVG are switched to their opposite values.

7. The voltage source type SVG control method according to claim 6, characterized in that, The stability condition is characterized by the fact that the rate of change of the power angle, the rate of change of active power, and the power angle acceleration are all greater than zero.

8. A voltage source type SVG control device, characterized in that, The control unit applied to the wind farm voltage source type SVG of claim 1, the device comprising: The parameter acquisition unit is used to determine the power angle change rate, power angle change acceleration, and active power change rate of the SVG based on the power angle between the voltage source type SVG and the power grid. The condition judgment unit is used to determine whether the power angle meets the preset stability condition based on the values ​​of the power angle change rate, the power angle change acceleration, and the active power change rate. A stability control unit is configured to switch the current inertia coefficient and damping coefficient values ​​of the SVG to their opposite values ​​in response to the fact that the power angle does not meet the stability condition.

9. The voltage source type SVG control device according to claim 8, characterized in that, The stability condition is characterized by the fact that the rate of change of the power angle, the rate of change of active power, and the power angle acceleration are all greater than zero.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the voltage source type SVG control method according to any one of claims 6 to 7.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the voltage source type SVG control method according to any one of claims 6 to 7.

12. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the voltage source type SVG control method according to any one of claims 6 to 7.

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