AC / DC power grid reactive power coordination control method and system, electronic equipment and computer readable storage medium

Abstract

The invention discloses an AC / DC power grid reactive power coordination control method and system, electronic equipment and a computer readable storage medium, and the method comprises the steps: carrying out the state judgment of each embedded DC system related to a normal operation state and a commutation failure state based on the real-time operation characteristic data of the embedded DC system; and whether the reactive power supply carries out voltage support control is carried out according to the state of the embedded direct current system, and the design is beneficial to optimizing reactive power flow distribution in a configuration system, improving the transmission capability and voltage stability of a transmission line and improving the anti-interference capability of a power grid. According to the method, when the reactive power supply is controlled, reactive coordination control capable of avoiding reactive competition is adopted, distribution of reactive compensation power in the power grid can be balanced more reasonably, and the utilization efficiency of reactive power and the overall operation efficiency of the power grid are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of power systems, and in particular relates to a method, system, electronic equipment and computer-readable storage medium for coordinated reactive power control of an AC or DC power grid. Background Art

[0002] DC technology has the advantages of fast and flexible power regulation, no increase in system short-circuit capacity, low loss and small footprint, and is widely used in scenarios such as long-distance large-capacity power transmission, asynchronous networking, and submarine cable transmission. Unlike traditional large-capacity long-distance DC transmission technology, the converter stations at both ends of the "embedded DC" transmission technology are built within the same AC power grid, usually using existing overhead transmission lines to "convert AC to DC" and existing or reserved AC cable channels, which can greatly improve the power grid's transmission capacity and the controllability and flexibility of the grid within the limited transmission corridor space.

[0003] However, "embedded DC" still has the disadvantage of the risk of commutation failure of conventional DC. Once the system reactive power support is insufficient, it may cause continuous commutation failure of "embedded DC". If the reactive power of the system can be fully mobilized, it will support voltage recovery in time after the failure of "embedded DC". For example, pumped storage units can generate reactive power to improve the voltage support capacity of the power grid. If the reactive voltage support capacity of existing pumped storage units can be fully utilized, the economic benefits will be significant. In particular, pumped storage units that are close to the "embedded DC" converter station in electrical distance can undertake the reactive voltage support task of the converter station.

[0004] In addition to traditional reactive power sources (such as phase-shifting devices and SVG), there are also reactive power sources with reactive output capabilities (such as pumped storage units) in the power grid, but their voltage support capabilities have not yet been explored. For example, most pumped storage power stations are mainly used in "energy-type" applications such as peak shaving and valley filling. Most pumped storage units have a small number of phase-shifting operations and a small duration, which fails to give full play to the phase-shifting effect of the units. In addition, there has been no in-depth research on the "embedded DC" technology, and there is no reactive coordination control strategy for provincial AC / DC power grids containing embedded DC systems. In order to fully tap the reactive support potential of reactive power sources around the "embedded DC" and effectively improve the voltage recovery characteristics of the "embedded DC", it is urgent to study the reactive coordination control strategy for provincial AC / DC power grids containing embedded DC systems. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention proposes a method, system, electronic device and computer-readable storage medium for coordinated reactive power control of an AC / DC power grid.

[0006] The technical solution of the present invention is as follows:

[0007] A reactive power coordinated control method for an AC / DC power grid, wherein the AC / DC power grid is provided with a plurality of groups of embedded DC systems and reactive power sources, comprising:

[0008] Based on the real-time operation characteristic data of the embedded DC system, the state determination related to the normal operation state and the commutation failure state of each embedded DC system is performed;

[0009] If at least one embedded DC system is determined to be in a commutation failure state, the control target is to restore the bus voltage that has dropped due to the commutation failure, and the reactive power supply is subjected to reactive coordinated control to avoid reactive power contention; if each embedded DC system is determined to be in a normal operating state, the local target of the reactive power supply is used as the control target, and the reactive power supply is subjected to automatic voltage control for a stable operation process.

[0010] Furthermore, the reactive power source is a pumped storage unit, a battery energy storage device, a flywheel energy storage device or a distributed power source.

[0011] Furthermore, the specific method for determining the state of each embedded DC system related to the normal operation state and the commutation failure state based on the real-time operation characteristic data of the embedded DC system includes:

[0012] Real-time acquisition of the bus voltage value U of the embedded DC system ac and the inverter station thyristor turn-off angle γ, and the bus voltage value U ac The inverter station thyristor turn-off angle γ is compared with the set critical bus voltage value and the inverter station thyristor turn-off angle threshold γ′ is compared. If γ<γ′ or U ac <U min , the embedded DC system is judged to be in a commutation failure state; if γ≥γ′ and U ac ≥U min , the embedded DC system is judged to be in normal operation state.

[0013] Furthermore, the method for obtaining the thyristor turn-off angle γ of the inverter station of the embedded DC system includes:

[0014] The inverter station thyristor advance trigger angle β and bus voltage value U based on real-time embedded DC system ac And the DC current I dc , combined with the inverter transformer ratio K and transformer leakage reactance X, the inverter station thyristor turn-off angle γ of the embedded DC system is calculated by the following formula:

[0015]

[0016] Furthermore, the set inverter station thyristor turn-off angle threshold γ′=7°.

[0017] Furthermore, the calculation method of the set critical bus voltage value is as follows:

[0018]

[0019] In the formula, γ min It is the minimum turn-off angle of the thyristor in the inverter station.

[0020] Furthermore, the specific method of performing reactive coordinated control on the reactive power source to avoid reactive power contention includes:

[0021] The output of the reactive power source is controlled according to a reactive coordination control model, and the expression of the reactive coordination control model is:

[0022] Q s =Q ref +ΔQ ref

[0023]

[0024]

[0025] In the formula, Q s is the output of reactive power; Q ref The reactive power reference value of the reactive power source based on the local control target; ΔQ ref is the reference value of reactive power compensation for reactive power source; ΔQ ref,i is the reactive power compensation amount of the i-th embedded DC system by the reactive power source, i is the serial number of the embedded DC system, i∈[1,n], and n is the total number of embedded DC systems; χ is the control state quantity of the reactive power source, χ=0 means that the reactive power source performs automatic voltage control, and χ=1 means that the reactive power source performs reactive coordinated control; F ci is the operating state of the i-th embedded DC system, F ci =0 means that the i-th embedded DC system is in normal operation, F ci =1 indicates that the i-th embedded DC system is in a commutation failure state; ΔV i is the difference between the measured value and the reference value of the commutation bus voltage of the i-th embedded DC system; D i is the droop coefficient of the i-th embedded DC system.

[0026] A reactive power coordination control system for an AC / DC power grid, wherein the AC / DC power grid is provided with a plurality of embedded DC systems and reactive power supplies, including a state determination module and a control module;

[0027] The state determination module is used to determine the state of each embedded DC system related to the normal operation state and the commutation failure state based on the real-time operation characteristic data of the embedded DC system;

[0028] The control module is used to control according to the state of the embedded DC system. If at least one embedded DC system is determined to be in a commutation failure state, the control target is to restore the bus voltage dropped due to the commutation failure, and the reactive power supply is subjected to reactive coordinated control to avoid reactive power contention; if each embedded DC system is determined to be in a normal operating state, the local target of the reactive power supply is used as the control target, and the reactive power supply is subjected to automatic voltage control for a stable operation process.

[0029] Furthermore, the reactive power source is a pumped storage unit, a battery energy storage device, a flywheel energy storage device or a distributed power source.

[0030] Furthermore, the specific method for determining the state of each embedded DC system related to the normal operation state and the commutation failure state based on the real-time operation characteristic data of the embedded DC system includes:

[0031] Real-time acquisition of the bus voltage value U of the embedded DC system ac and the inverter station thyristor turn-off angle γ, and the bus voltage value U ac The inverter station thyristor turn-off angle γ is compared with the set critical bus voltage value and the inverter station thyristor turn-off angle threshold γ′ is compared. If γ<γ′ or U ac <U min , the embedded DC system is judged to be in a commutation failure state; if γ≥γ′ and U ac ≥U min , the embedded DC system is judged to be in normal operation state.

[0032] Furthermore, the method for obtaining the thyristor turn-off angle γ of the inverter station of the embedded DC system includes:

[0033] The inverter station thyristor advance trigger angle β and bus voltage value U based on real-time embedded DC system ac And the DC current I dc , combined with the inverter transformer ratio K and transformer leakage reactance X, the inverter station thyristor turn-off angle γ of the embedded DC system is calculated by the following formula:

[0034]

[0035] Furthermore, the set inverter station thyristor turn-off angle threshold γ′=7°.

[0036] Furthermore, the calculation method of the set critical bus voltage value is as follows:

[0037]

[0038] In the formula, γ min It is the minimum turn-off angle of the thyristor in the inverter station.

[0039] Furthermore, the specific method of performing reactive coordinated control on the reactive power source to avoid reactive power contention includes:

[0040] The output of the reactive power source is controlled according to a reactive coordination control model, and the expression of the reactive coordination control model is:

[0041] Q s =Q ref +ΔQ ref

[0042]

[0043]

[0044] In the formula, Q s is the output of reactive power; Q ref The reactive power reference value of the reactive power source based on the local control target; ΔQ ref is the reference value of reactive power compensation for reactive power source; ΔQ ref,i is the reactive power compensation amount of the i-th embedded DC system by the reactive power source, i is the serial number of the embedded DC system, i∈[1,n], and n is the total number of embedded DC systems; χ is the control state quantity of the reactive power source, χ=0 means that the reactive power source performs automatic voltage control, and χ=1 means that the reactive power source performs reactive coordinated control; F ci is the operating state of the i-th embedded DC system, F ci =0 means that the i-th embedded DC system is in normal operation, F ci =1 indicates that the i-th embedded DC system is in a commutation failure state; ΔV i is the difference between the measured value and the reference value of the commutation bus voltage of the i-th embedded DC system; D i is the droop coefficient of the i-th embedded DC system.

[0045] An electronic device comprises a memory and a processor, wherein the memory stores a computer program, and the processor is used to call and run the computer program stored in the memory to execute any of the methods described above.

[0046] A computer-readable storage medium stores a computer program, wherein the computer program implements the steps of any of the above methods when executed by a processor.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The present invention proposes a reactive power coordinated control method for AC / DC power grids. The method is based on the real-time operating characteristic data of the embedded DC system, performs status judgment on each embedded DC system related to the normal operating state and the commutation failure state, and then controls whether the reactive power source performs voltage support according to the state of the embedded DC system. The design helps to optimize the reactive power flow distribution in the configuration system, improve the transmission capacity and voltage stability of the transmission line, and enhance the anti-interference ability of the power grid.

[0049] The method of the present invention adopts reactive coordination control to avoid reactive power contention when controlling reactive power sources. This design can more reasonably balance the distribution of reactive compensation power in the power grid, thereby improving reactive power utilization efficiency and overall power grid operation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of reactive power coordinated control structure in the embodiment;

[0051] Figure 2 It is a flow chart of the reactive power coordination control method of AC / DC power grids containing an embedded DC system in an embodiment;

[0052] Figure 3 It is a logic block diagram of reactive power coordination control action in the embodiment;

[0053] Figure 4 It is a reactive power coordinated control strategy diagram in the embodiment;

[0054] Figure 5 It is a schematic diagram of electrical connection between a reactive power source and an embedded DC system in an AC / DC power grid in an application embodiment;

[0055] Figure 6 A comparison diagram of the inverter bus voltage of the embedded DC system in the application embodiment;

[0056] Figure 7 It is a comparison diagram of reactive power output in the application embodiment. DETAILED DESCRIPTION

[0057] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent modifications of the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0058] Embodiment 1:

[0059] A reactive power coordinated control method for an AC / DC power grid according to the present invention is as follows: Figure 1 As shown in FIG. 1 , there are several groups of embedded DC systems and reactive power sources in the AC / DC power grid. The reactive coordination control system sends control signals to the reactive power sources to support the voltage of the commutation busbars of each embedded DC system, such as Figure 2 As shown, the method comprises the following specific steps:

[0060] S1. Based on the real-time operation characteristic data of the embedded DC system, a state determination is performed on each embedded DC system in relation to a normal operation state and a commutation failure state;

[0061] S2. Control is performed according to the state of the embedded DC system. If at least one embedded DC system is determined to be in a commutation failure state, the control target is to restore the bus voltage that has dropped due to the commutation failure, and the reactive power supply is subjected to reactive coordinated control to avoid reactive power contention; if each embedded DC system is determined to be in a normal operating state, the local target of the reactive power supply is used as the control target (i.e., the local voltage monitoring signal is used as the control signal), and the reactive power supply is subjected to automatic voltage control for a stable operating process.

[0062] Embodiment 2:

[0063] This embodiment is further designed on the basis of the first embodiment in that the reactive power source in this embodiment is a pumped storage unit, a battery energy storage device, a flywheel energy storage device or a distributed power source.

[0064] Embodiment three:

[0065] This embodiment is further designed on the basis of the first embodiment in that, in this embodiment, based on the real-time operation characteristic data of the embedded DC system, the specific method for determining the state of each embedded DC system related to the normal operation state and the commutation failure state includes:

[0066] Commutation failure is determined by the working characteristics of thyristor devices. The turn-off angle is a key indicator of the thyristor's blocking ability and is also the main basis for determining the risk of commutation failure. When a fault occurs in the inverter-side AC system, different changes in the trigger angle caused by different short-circuit fault types can significantly affect the commutation overlap time, but its effect on the reverse resistance of the thyristor is limited. Considering factors such as the trigger angle, DC current and AC system voltage, the comparison result between the turn-off angle and the turn-off angle threshold is used as the criterion for commutation failure of the converter in engineering applications.

[0067] Monitor the bus voltage value U of the embedded DC system ac And the inverter station thyristor turn-off angle γ, and the bus voltage value Uac The inverter station thyristor turn-off angle γ is compared with the set critical bus voltage value and the inverter station thyristor turn-off angle threshold γ′ is compared. If γ < γ′ or U ac <U min , the embedded DC system is determined to be in a commutation failure state; otherwise, the embedded DC system is determined to be in a normal operating state.

[0068] Embodiment 4:

[0069] This embodiment is further designed on the basis of the third embodiment in that the method for obtaining the thyristor turn-off angle γ of the inverter station of the embedded DC system in this embodiment includes:

[0070] The inverter station thyristor advance trigger angle β and bus voltage value U based on real-time embedded DC system ac And the DC current I dc , combined with the inverter transformer ratio K and transformer leakage reactance X, the inverter station thyristor turn-off angle γ of the embedded DC system is calculated:

[0071]

[0072] Embodiment five:

[0073] This embodiment is further designed on the basis of the fourth embodiment in that the inverter station thyristor turn-off angle threshold γ′ is set to be 7°.

[0074] Embodiment six:

[0075] This embodiment is further designed on the basis of the fourth embodiment in that the calculation method of the critical bus voltage value set in this embodiment is as follows:

[0076]

[0077] In the formula, γ min It is the minimum turn-off angle of the thyristor in the inverter station, which is generally taken as 7°.

[0078] Embodiment seven:

[0079] This embodiment is further designed on the basis of the first embodiment in that, in this embodiment, if at least one embedded DC system is determined to be in a commutation failure state, the specific method of performing reactive coordinated control of reactive power sources to avoid reactive power contention with the bus voltage dropped due to the commutation failure as the control target includes:

[0080] The output of reactive power source is controlled according to the reactive coordination control model. The expression of reactive coordination control model is:

[0081] Q s =Q ref +ΔQref

[0082]

[0083] In the formula, Q s is the output of reactive power; Q ref The reactive power reference value of the reactive power source based on the local control target; ΔQ ref is the reference value of reactive power compensation for reactive power source; ΔQ ref,i is the reactive power compensation amount of the i-th embedded DC system by the reactive power source, i is the serial number of the embedded DC system, i∈[1,n], and n is the total number of embedded DC systems; χ is the control state quantity of the reactive power source, χ=0 means that the reactive power source performs automatic voltage control, and χ=1 means that the reactive power source performs reactive coordinated control; F ci is the operating state of the i-th embedded DC system, F ci =0 means that the i-th embedded DC system is in normal operation, F ci =1 indicates that the i-th embedded DC system is in a commutation failure state; ΔV i is the difference between the measured value and the reference value of the commutation bus voltage of the i-th embedded DC system; D i is the droop coefficient of the i-th embedded DC system.

[0084] By adjusting the droop coefficient D i , which can ensure the distribution of reactive power control quantity among various reactive power sources, thus avoiding problems such as reactive power competition and power flow uncertainty caused by different control sensitivities.

[0085] Embodiment eight:

[0086] The invention provides an AC / DC power grid reactive power coordination control system, wherein the AC / DC power grid is provided with a plurality of embedded DC systems and DC power supplies, including a state determination module and a control module;

[0087] A state determination module, for determining the state of each embedded DC system in relation to a normal operation state and a commutation failure state based on real-time operation characteristic data of the embedded DC system;

[0088] The control module is used to control according to the state of the embedded DC system. If at least one embedded DC system is determined to be in a commutation failure state, the control target is to restore the bus voltage dropped due to the commutation failure, and the reactive power supply is subjected to reactive coordinated control to avoid reactive power contention; if each embedded DC system is determined to be in a normal operating state, the local target of the reactive power supply is used as the control target, and the reactive power supply is subjected to automatic voltage control for a stable operating process.

[0089] Furthermore, the reactive power source is a pumped storage unit, a battery energy storage device, a flywheel energy storage device or a distributed power source.

[0090] Furthermore, the specific method for determining the state of each embedded DC system related to the normal operation state and the commutation failure state based on the real-time operation characteristic data of the embedded DC system includes:

[0091] Real-time acquisition of the bus voltage value U of the embedded DC system ac and the inverter station thyristor turn-off angle γ, and the bus voltage value U ac The inverter station thyristor turn-off angle γ is compared with the set critical bus voltage value and the inverter station thyristor turn-off angle threshold γ′ is compared. If γ<γ′ or U ac <U min , the embedded DC system is judged to be in a commutation failure state; if γ≥γ′ and U ac ≥U min , the embedded DC system is judged to be in normal operation state.

[0092] Furthermore, the method for obtaining the thyristor turn-off angle γ of the inverter station of the embedded DC system includes:

[0093] The inverter station thyristor advance trigger angle β and bus voltage value U based on real-time embedded DC system ac And the DC current I dc , combined with the inverter transformer ratio K and transformer leakage reactance X, the inverter station thyristor turn-off angle γ of the embedded DC system is calculated by the following formula:

[0094]

[0095] Furthermore, the set inverter station thyristor turn-off angle threshold γ′=7°.

[0096] Furthermore, the calculation method of the set critical bus voltage value is as follows:

[0097]

[0098] In the formula, γ min It is the minimum turn-off angle of the thyristor in the inverter station.

[0099] Furthermore, the specific method of performing reactive coordinated control on the reactive power source to avoid reactive power contention includes:

[0100] The output of the reactive power source is controlled according to a reactive coordination control model, and the expression of the reactive coordination control model is:

[0101] Q s =Qref +ΔQ ref

[0102]

[0103] In the formula, Q s is the output of reactive power; Q ref The reactive power reference value of the reactive power source based on the local control target; ΔQ ref is the reference value of reactive power compensation for reactive power source; ΔQ ref,i is the reactive power compensation amount of the i-th embedded DC system by the reactive power source, i is the serial number of the embedded DC system, i∈[1,n], and n is the total number of embedded DC systems; χ is the control state quantity of the reactive power source, χ=0 means that the reactive power source performs automatic voltage control, and χ=1 means that the reactive power source performs reactive coordinated control; F ci is the operating state of the i-th embedded DC system, F ci =0 means that the i-th embedded DC system is in normal operation, F ci =1 indicates that the i-th embedded DC system is in a commutation failure state; ΔV i is the difference between the measured value and the reference value of the commutation bus voltage of the i-th embedded DC system; D i is the droop coefficient of the i-th embedded DC system.

[0104] In the reactive power coordinated control of AC / DC power grids, the local voltage monitoring signal is used to determine whether the embedded DC has a commutation failure. Then the coordinated control system takes effect and sends a control signal to the reactive power source to mobilize nearby reactive power sources to provide voltage support for the embedded DC commutation bus. Figure 1 The voltages of the commutation bus 1 to the commutation bus n are V1...V n When the commutation bus voltage has not recovered, the reactive power source should output reactive power as much as possible (i.e. the reactive power source outputs 100% reactive power) to help the commutation bus voltage recover. Figure 2 As shown, reactive power sources 1 to 4 all fully output 100% reactive power to help the commutation bus voltage recover.

[0105] Only when the embedded DC commutation fails near the reactive power source, the reactive power source provides voltage support for the embedded DC commutation bus. During normal operation, the reactive power source still uses the local voltage / reactive power as the control target.

[0106] The specific reactive power coordinated control action logic is as follows: Figure 3 As shown, V refi is the voltage reference value of the i-th embedded commutation bus, V siis the voltage measurement value of the i-th embedded commutation busbar. The voltage measurement value is compared with the commutation failure criterion to determine whether the embedded DC system has commutation failure. ci Indicates the state of the i-th embedded DC system. Under normal operation, F ci is 0, the reactive power source outputs reactive power with the local voltage / reactive signal as the control signal; if commutation failure occurs, F ci becomes 1, the reactive power source generates reactive power according to the control signal of the coordination controller until the static reactive power compensation device is activated and the system fully recovers to the steady-state point F ci It will return to 0.

[0107] As the commutation bus voltage recovers, the reactive power shortage of the embedded system no longer requires all units to supply full reactive power at the same time. Due to the different control sensitivities of each unit, reactive power distribution problems will arise. Before the static reactive power compensation device is activated, a reactive coordination control model with a differential coefficient can be used to determine the reasonable distribution of reactive control quantities among various embedded DC systems, thereby solving the reactive power competition problem.

[0108] For the coordinated controller strategy of reactive power source, Figure 4 shown.

[0109] exist Figure 4 In the process, the embedded DC bus voltage is first measured in real time, and the bus voltage deviation is obtained by comparing it with the reference value. The embedded DC state is judged according to the commutation failure criterion, ΔV i That is, the difference between the measured value of the i-th embedded DC converter bus voltage and the reference value, V si is the voltage measurement value of the i-th embedded commutation bus. By monitoring the embedded DC, F ci To represent the operating state of the i-th embedded DC system, under normal operating conditions, F ci If commutation failure occurs, F ci becomes 1, the embedded DC reactive power demand changes, and the reactive power controller outputs a control signal to control the reactive power output until the static reactive power compensation device is activated and the system fully recovers to the steady-state point F. ci The reactive power regulation is generated by droop control, and the embedded DC reactive power regulation signals are added together, and the total reactive power regulation instruction is generated through the integral control link, where D i is the droop coefficient, K b is the proportional coefficient of the integral controller, and s is the Laplace operator in the time domain.

[0110] After the static reactive power compensation device is fully activated, the commutation bus voltage of the embedded DC system is restored to the rated value, and the control variable of the reactive power source is automatically restored to the local signal reference value.

[0111] Embodiment nine:

[0112] An electronic device includes a memory and a processor, wherein the memory stores a computer program, and the processor is used to call and run the computer program stored in the memory to execute the method of any of the above embodiments.

[0113] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of any of the above embodiments are implemented.

[0114] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0115] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes 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 a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0116] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0117] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0118] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0119] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0120] Application examples:

[0121] This example analyzes the East China Power Grid under the high-power operation mode in the summer of 2025, and simulates the implementation of the control method of the present invention to verify the effectiveness of the present invention. The electrical connection relationship diagram between the embedded DC system and the reactive power supply constructed during the simulation implementation is shown in the figure below: Figure 5 As shown, the pumped storage unit is connected to the embedded DC bus 1 through a line at the bus 4. The reactive power source in the power grid is the pumped storage unit near the embedded DC. The specific parameters of the embedded DC are shown in Table 1.

[0122] Table 1 Main parameters of embedded DC system

[0123] name Embedded DC Rated power(MW) 400 Power Cap (MW) 500 Rated DC voltage(kV) 400 Line impedance(Ω) 1.0

[0124] The reactive power source near the DC can provide a certain reactive power support capability for the DC, and the closer the relative electrical distance between the reactive power source and the embedded DC, the stronger the reactive power support capability for the embedded DC bus. Figure 5 It can be seen that a total of 6 pumped storage units at bus 4 are selected as reactive power sources, which are relatively close to the embedded DC inverter bus 1. Assume that a three-phase short circuit fault occurs at the embedded DC inverter bus 1, and the fault is cleared after 0.1s. Compare the bus voltage recovery of the inverter station with and without the AC / DC grid reactive power coordinated control method containing an embedded DC system.

[0125] like Figure 6 and Figure 7It can be seen from the simulation results that if the reactive power coordinated control method of the AC / DC power grid containing an embedded DC system of the present invention is adopted, the jump voltage of the embedded DC is increased from 0.84 to 0.92. Since the reference power in the figure is 100MVar, it is observed that the reactive power supply provides about 200MVar more reactive power to the power grid during 0.4s to 0.5s. It can be seen from the simulation results that the reactive power coordinated control method of the AC / DC power grid containing an embedded DC system of the present invention is conducive to improving the voltage recovery characteristics of the embedded DC.

[0126] The above description is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a technician familiar with the technical field within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A reactive power coordinated control method for an AC / DC power grid, wherein the AC / DC power grid is provided with a plurality of embedded DC systems and reactive power sources, characterized in that: include: Based on the real-time operation characteristic data of the embedded DC system, the state determination related to the normal operation state and the commutation failure state of each embedded DC system is performed; If at least one embedded DC system is determined to be in a commutation failure state, the control target is to restore the bus voltage that has dropped due to the commutation failure, and the reactive power supply is subjected to reactive coordinated control to avoid reactive power contention; if each embedded DC system is determined to be in a normal operating state, the local target of the reactive power supply is used as the control target, and the reactive power supply is subjected to automatic voltage control for a stable operation process.

2. The method for coordinated reactive power control of AC and DC power grids according to claim 1, characterized in that: The reactive power source is a pumped storage unit, a battery energy storage device, a flywheel energy storage device or a distributed power source.

3. The method for coordinated reactive power control of AC and DC power grids according to claim 1, characterized in that: The specific method for determining the state of each embedded DC system related to the normal operation state and the commutation failure state based on the real-time operation characteristic data of the embedded DC system includes: Real-time acquisition of the bus voltage value U of the embedded DC system ac and the inverter station thyristor turn-off angle γ, and the bus voltage value U ac The inverter station thyristor turn-off angle γ is compared with the set critical bus voltage value and the inverter station thyristor turn-off angle threshold γ′ is compared. If γ<γ′ or U ac <U min , the embedded DC system is judged to be in a commutation failure state; if γ≥γ′ and U ac ≥U min , the embedded DC system is judged to be in normal operation state.

4. The method for coordinated reactive power control of AC and DC power grids according to claim 3, characterized in that: The method for obtaining the thyristor turn-off angle γ of the inverter station of the embedded DC system includes: The inverter station thyristor advance trigger angle β and bus voltage value U based on real-time embedded DC system ac And the DC current I dc , combined with the inverter transformer ratio K and transformer leakage reactance X, the inverter station thyristor turn-off angle γ of the embedded DC system is calculated by the following formula:

5. The method for coordinated reactive power control of AC and DC power grids according to claim 3, characterized in that: The set inverter station thyristor turn-off angle threshold γ′=7°.

6. The method for coordinated reactive power control of AC and DC power grids according to claim 4, characterized in that: The calculation method of the set critical bus voltage value is as follows: In the formula, γ min It is the minimum turn-off angle of the thyristor in the inverter station.

7. The method for coordinated reactive power control of AC and DC power grids according to claim 1, characterized in that: The specific method of performing reactive coordinated control on the reactive power source to avoid reactive power contention includes: The output of the reactive power source is controlled according to a reactive coordination control model, and the expression of the reactive coordination control model is: Q s =Q ref +ΔQ ref In the formula, Q s is the output of reactive power; Q ref The reactive power reference value of the reactive power source based on the local control target; ΔQ ref is the reference value of reactive power compensation for reactive power source; ΔQ ref,i is the reactive power compensation amount of the i-th embedded DC system by the reactive power source, i is the serial number of the embedded DC system, i∈[1,n], and n is the total number of embedded DC systems; χ is the control state quantity of the reactive power source, χ=0 means that the reactive power source performs automatic voltage control, and χ=1 means that the reactive power source performs reactive coordinated control; F ci is the operating state of the i-th embedded DC system, F ci =0 means that the i-th embedded DC system is in normal operation, F ci =1 indicates that the i-th embedded DC system is in a commutation failure state; ΔV i is the difference between the measured value and the reference value of the commutation bus voltage of the i-th embedded DC system; D i is the droop coefficient of the i-th embedded DC system.

8. A reactive power coordination control system for an AC / DC power grid, wherein the AC / DC power grid is provided with a plurality of embedded DC systems and reactive power supplies, characterized in that: It includes a state determination module and a control module; The state determination module is used to determine the state of each embedded DC system related to the normal operation state and the commutation failure state based on the real-time operation characteristic data of the embedded DC system; The control module is used to control according to the state of the embedded DC system. If at least one embedded DC system is determined to be in a commutation failure state, the control target is to restore the bus voltage dropped due to the commutation failure, and the reactive power supply is subjected to reactive coordinated control to avoid reactive power contention; if each embedded DC system is determined to be in a normal operating state, the local target of the reactive power supply is used as the control target, and the reactive power supply is subjected to automatic voltage control for a stable operation process.

9. An electronic device, characterized in that: The electronic device comprises a memory and a processor, wherein the memory stores a computer program, and the processor is configured to call and run the computer program stored in the memory to execute the method according to any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method as claimed in any one of claims 1 to 7 are implemented.

Images