A coordinated control method and system for suppressing overvoltage of power grid

Abstract

The application discloses a kind of coordinated control method and system for inhibiting power grid overvoltage, according to grid voltage and phase modifier steady-state displacement, construct the control strategy of reactive power source for inhibiting power grid overvoltage, in the control strategy of reactive power source, consider the voltage counter-regulation caused by the action delay of SVC, only after DC commutation failure according to grid voltage trajectory Trigger SVC coordinated control, in the case of power grid overvoltage, add phase modifier to DC reactive power compensation system, make it with original converter station filter, DC reactive power compensation capacitor coordinated as the operation of new DC reactive power compensation system, according to grid voltage situation Control phase modifier and SVC, realized that multiple types of reactive power source inhibit power grid whole process overvoltage, improve the voltage comprehensive control level of high proportion new energy DC external sending system.

Description

Technical Field

[0001] This invention relates to a coordinated control method and system for suppressing power grid overvoltage, belonging to the field of power grid safe and stable operation control technology. Background Technology

[0002] With the large-scale integration of new energy sources and DC power electronic equipment into the power grid, commutation failure and blocking have become the most common fault types in high-voltage DC transmission systems. After a fault occurs, the DC power drops rapidly during the transient period, and the reactive power of the AC filter at the converter station is fed back to the AC grid. At the same time, due to the significant decrease in power flow in the nearby lines, a large amount of reactive power is released, resulting in a very prominent overvoltage problem in the system, and even triggering a cascading blackout.

[0003] Currently, there are two main types of measures to address overvoltage after DC commutation failures and blockages. The first is based on DC control and protection logic, which involves delaying the turn-off time of the converter valve after DC blockage or adjusting the DC low-voltage current limiting parameters to maintain DC current and reactive power consumption during DC faults, thus suppressing transient voltage increases. However, this may also affect the DC and other aspects of grid operation and control characteristics. The second approach focuses on reactive power resource coordination control. This involves considering the reactive power and voltage control characteristics of the DC sending-end synchronous condenser and coordinating with reactive power resources such as renewable energy plants, converter station filters, and SVCs to reduce transient overvoltage after DC faults. However, reactive power and voltage control requires comprehensive coordination of different types of grid faults, time scales, and voltage issues to maximize the utilization of the grid's reactive power resources. Therefore, it is necessary to systematically study multi-type reactive power resource coordination control to address overvoltage. Summary of the Invention

[0004] This invention provides a coordinated control method and system for suppressing power grid overvoltage, which solves the problems disclosed in the background art.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A coordinated control method for suppressing power grid overvoltage includes:

[0007] Based on the DC fault set that causes overvoltage grid disconnection of new energy sources and the calculation model of the maximum steady-state displacement of synchronous condensers, the steady-state displacement of synchronous condensers is calculated.

[0008] Based on the grid voltage and the steady-state commutation of the synchronous condenser, a reactive power source control strategy to suppress grid overvoltage is constructed. The reactive power source control strategy is as follows: SVC coordinated control is triggered based on the grid voltage trajectory after DC commutation failure; in the case of grid overvoltage, the synchronous condenser is added to the DC reactive power compensation system, and the synchronous condenser is controlled according to the grid voltage.

[0009] Reactive power source control of the power grid is carried out according to the reactive power source control strategy to suppress power grid overvoltage.

[0010] Based on the DC fault set causing overvoltage grid disconnection of new energy sources and the calculation model of the maximum steady-state displacement of the synchronous condenser, the steady-state displacement of the synchronous condenser is calculated, including:

[0011] Based on the DC fault set that causes overvoltage disconnection of new energy and the calculation model of the maximum steady-state displacement of synchronous condensers, the maximum steady-state displacement of synchronous condensers under each fault in the DC fault set is calculated, and the minimum value among the maximum steady-state displacements of synchronous condensers is taken as the steady-state displacement of synchronous condensers.

[0012] The calculation model for the maximum steady-state permutation of the synchronous condenser satisfies the following constraints:

[0013]

[0014] Among them, Q flt Q represents the total reactive power of the AC filter bank and DC reactive power compensation capacitor bank in the converter station of the DC reactive power compensation system. con Q is the reactive power generated by the synchronous condenser in steady state. ac The reactive power provided by the AC power grid system, Q dc N represents the reactive power consumed during DC power transmission, where n is the total number of AC filter banks and DC reactive power compensation capacitor banks in the converter station. flt,min V represents the minimum number of AC filter banks at the converter station corresponding to the operating range where the DC transmission power is located. i,min V is the voltage of the i-th node in the power grid. i The lower limit, V i,max V is the voltage of the i-th node in the power grid. i The upper limit of Q j,min The steady-state reactive power output Q of the j-th reactive power source in the power grid j Lower limit, Q j,max The steady-state reactive power output Q of the j-th reactive power source in the power grid j Upper limit.

[0015] Reactive power source control strategies include:

[0016] After a DC fault, if the grid voltage is detected to be less than the threshold V fail If no DC blocking signal is detected, DC commutation fails. During the DC commutation failure period, a shutdown signal is sent to the SVC. When the measured grid voltage is not less than the threshold V... fail And the duration is not less than the threshold T com Send a recovery signal to the SVC;

[0017] During the transient process following a DC fault, if an overvoltage is detected in the power grid, a mode adjustment command is sent to the synchronous condenser to make it operate in constant voltage control mode; if no overvoltage is detected in the power grid, a mode adjustment command is sent to the synchronous condenser to make it operate in constant reactive power control mode.

[0018] During the steady-state recovery period after a DC fault is cleared, the grid voltage drops after adjustment by a synchronous condenser. If U≤U set2 And t≥t set2 Then, a mode adjustment command is sent to the synchronous condenser to make it operate in a constant reactive power control mode, where the reactive power of the synchronous condenser is U = U set2 And t = t set2 The reactive power output of the time; if the reactive power output of the time-regulating camera equals the lower limit of reactive power output, and U > U set2 Then, the nearby capacitor bank is disconnected or the reactor is connected in stages until the grid voltage is controlled within the normal range; where U is the grid voltage, t is the duration of U, and U set2 t represents the upper limit of voltage during normal operation of the power grid. set2 For U set2 The duration.

[0019] A coordinated control system for suppressing power grid overvoltage includes:

[0020] Replacement Quantity Calculation Module: Based on the DC fault set that causes overvoltage disconnection of new energy and the calculation model of the maximum steady-state replacement quantity of the synchronous condenser, calculate the steady-state replacement quantity of the synchronous condenser;

[0021] Strategy Construction Module: Based on the grid voltage and the steady-state commutation of the synchronous condenser, a reactive power source control strategy to suppress grid overvoltage is constructed. The reactive power source control strategy is as follows: SVC coordinated control is triggered based on the grid voltage trajectory after DC commutation failure; in the case of grid overvoltage, the synchronous condenser is added to the DC reactive power compensation system, and the synchronous condenser is controlled according to the grid voltage.

[0022] Control module: Performs reactive power control of the power grid according to the reactive power control strategy to suppress power grid overvoltage.

[0023] Replacement Quantity Calculation Module: Based on the DC fault set that causes overvoltage disconnection of new energy and the calculation model of maximum steady-state replacement quantity of synchronous condenser, calculate the maximum steady-state replacement quantity of synchronous condenser under each fault in the DC fault set, and take the minimum value among the maximum steady-state replacement quantities of synchronous condenser as the steady-state replacement quantity of synchronous condenser.

[0024] The calculation model for the maximum steady-state permutation of the synchronous condenser satisfies the following constraints:

[0025]

[0026] Among them, Q flt Q represents the total reactive power of the AC filter bank and DC reactive power compensation capacitor bank in the converter station of the DC reactive power compensation system. con Q is the reactive power generated by the synchronous condenser in steady state. ac The reactive power provided by the AC power grid system, Q dcN represents the reactive power consumed during DC power transmission, where n is the total number of AC filter banks and DC reactive power compensation capacitor banks in the converter station. flt,min V represents the minimum number of AC filter banks at the converter station corresponding to the operating range where the DC transmission power is located. i,min V is the voltage of the i-th node in the power grid. i The lower limit, V i,max V is the voltage of the i-th node in the power grid. i The upper limit of Q j,min The steady-state reactive power output Q of the j-th reactive power source in the power grid j Lower limit, Q j,max The steady-state reactive power output Q of the j-th reactive power source in the power grid j Upper limit.

[0027] Reactive power source control strategies include:

[0028] After a DC fault, if the grid voltage is detected to be less than the threshold V fail If no DC blocking signal is detected, DC commutation fails. During the DC commutation failure period, a shutdown signal is sent to the SVC. When the measured grid voltage is not less than the threshold V... fail And the duration is not less than the threshold T com Send a recovery signal to the SVC;

[0029] During the transient process following a DC fault, if an overvoltage is detected in the power grid, a mode adjustment command is sent to the synchronous condenser to make it operate in constant voltage control mode; if no overvoltage is detected in the power grid, a mode adjustment command is sent to the synchronous condenser to make it operate in constant reactive power control mode.

[0030] During the steady-state recovery period after a DC fault is cleared, the grid voltage drops after adjustment by a synchronous condenser. If U≤U set2 And t≥t set2 Then, a mode adjustment command is sent to the synchronous condenser to make it operate in a constant reactive power control mode, where the reactive power of the synchronous condenser is U = U set2 And t = t set2 The reactive power output of the time; if the reactive power output of the time-regulating camera equals the lower limit of reactive power output, and U > U set2 Then, the nearby capacitor bank is disconnected or the reactor is connected in stages until the grid voltage is controlled within the normal range; where U is the grid voltage, t is the duration of U, and U set2 t represents the upper limit of voltage during normal operation of the power grid. set2 For U set2 The duration.

[0031] A computer-readable storage medium storing one or more programs, the one or more programs including instructions that, when executed by a computing device, cause the computing device to perform a coordinated control method for suppressing power grid overvoltages.

[0032] A computing device includes one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for performing a coordinated control method for suppressing power grid overvoltages.

[0033] The beneficial effects achieved by this invention are as follows: Based on the grid voltage and the steady-state displacement of the synchronous condenser, this invention constructs a reactive power source control strategy to suppress grid overvoltage. In the reactive power source control strategy, SVC coordinated control is triggered according to the grid voltage trajectory after DC commutation failure. In the case of grid overvoltage, the synchronous condenser is added to the DC reactive power compensation system, and the synchronous condenser is controlled according to the grid voltage situation. This realizes the suppression of grid overvoltage throughout the entire process by multiple types of reactive power sources, and improves the comprehensive voltage control level of the high-proportion new energy DC transmission system. Attached Figure Description

[0034] Figure 1 A flowchart of a coordinated control method for suppressing power grid overvoltage;

[0035] Figure 2 The synchronous condenser coordination control process for the new DC reactive power compensation system. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0037] like Figure 1 As shown, a coordinated control method for suppressing grid overvoltage includes the following steps:

[0038] Step 1: Calculate the steady-state replacement amount of the synchronous condenser based on the DC fault set that causes the new energy overvoltage grid disconnection and the calculation model of the maximum steady-state replacement amount of the synchronous condenser.

[0039] Step 2: Based on the grid voltage and the steady-state commutation of the synchronous condenser, construct a reactive power source control strategy to suppress grid overvoltage. The reactive power source control strategy is as follows: trigger SVC coordinated control based on the grid voltage trajectory after DC commutation failure; in the case of grid overvoltage, add the synchronous condenser to the DC reactive power compensation system, and control the synchronous condenser and SVC according to the grid voltage.

[0040] Step 3: Perform reactive power control of the power grid according to the reactive power control strategy to suppress power grid overvoltage.

[0041] The above method constructs a reactive power source control strategy to suppress grid overvoltage based on grid voltage and steady-state commutation of synchronous condensers. In the reactive power source control strategy, SVC coordinated control is triggered based on the grid voltage trajectory after DC commutation failure. In the case of grid overvoltage, the synchronous condenser is added to the DC reactive power compensation system. The synchronous condenser and SVC are controlled according to the grid voltage situation, realizing the suppression of grid overvoltage throughout the entire process by multiple types of reactive power sources, and improving the comprehensive voltage control level of the high-proportion new energy DC transmission system.

[0042] Before calculating the maximum steady-state displacement of the synchronous condenser, it is necessary to obtain the set of DC faults that cause overvoltage disconnection of renewable energy and some basic grid information. The basic grid information includes DC reactive power compensation, synchronous condenser output, and SVC configuration of renewable energy power plants. These data are all obtained based on grid electromechanical simulation data. When obtaining the set of DC faults, the typical mode is to simulate and analyze the transient voltage response characteristics after faults such as DC commutation failure and blocking, using full renewable energy generation and small start-up of conventional units as typical modes. The set of DC faults that cause overvoltage disconnection of renewable energy can be denoted as F.

[0043] The above calculation model involves replacing the capacitor banks used for reactive power compensation in the DC reactive power compensation system with the capacity of synchronous condensers, and then performing power flow calculations to satisfy the constraints. The model calculates the maximum steady-state replacement quantity Q of the synchronous condensers under each fault in the DC fault set. con,1 ... Q con,i Q con,i Let F be the maximum steady-state permutation value of the synchronous condenser under the i-th DC fault in F. Finally, the minimum value among the maximum steady-state permutation values ​​of the synchronous condenser is taken as the steady-state permutation value of the synchronous condenser. The calculation model must satisfy the following constraints:

[0044]

[0045] In the above formula, the constraints are as follows:

[0046] Q flt +Q con +Q ac =Q dc : An equality constraint between reactive power and DC reactive power consumption provided for reactive power, synchronous condensers, and the AC grid system in a DC reactive power compensation system; where Q flt Q represents the total reactive power of the AC filter bank and DC reactive power compensation capacitor bank in the converter station of the DC reactive power compensation system. con Q is the reactive power generated by the synchronous condenser in steady state. ac The reactive power provided by the AC power grid system, Q dc The reactive power consumed when transmitting power via DC;

[0047] n≥N flt,minThe total number of remaining filter banks and capacitor banks in the DC reactive power compensation system after replacement must be greater than the minimum number of filter banks corresponding to the operating range where the DC transmission power is located; where n is the total number of AC filter banks and DC reactive power compensation capacitor banks in the converter station, and N flt,min This represents the minimum number of AC filter banks for the converter station corresponding to the operating range where the DC transmission power is located.

[0048] V i,min <V i <V i,max The actual operating voltage of the power grid must meet the upper and lower limit constraints; among which, V i,min V is the voltage of the i-th node in the power grid. i The lower limit, V i,max V is the voltage of the i-th node in the power grid. i The upper limit;

[0049] Q j,min <Q j <Q j,max Each reactive power source has its corresponding maximum and minimum output; where Q j,min The steady-state reactive power output Q of the j-th reactive power source in the power grid j Lower limit, Q j,max The steady-state reactive power output Q of the j-th reactive power source in the power grid j Upper limit.

[0050] Based on the grid voltage and the steady-state displacement of the synchronous condenser, a reactive power source control strategy to suppress grid overvoltage is constructed. The reactive power sources specifically include SVC, synchronous condenser, converter station filter of DC reactive power compensation system and DC reactive power compensation capacitor, capacitor and reactor.

[0051] The reactive power source control strategy is as follows: Considering the voltage reversal caused by the SVC's operating delay, SVC coordinated control is triggered only after DC commutation failure, based on the grid voltage trajectory. In the event of grid overvoltage, the synchronous condenser is added to the DC reactive power compensation system, coordinating with the existing converter station filters and DC reactive power compensation capacitors to operate as a new DC reactive power compensation system. The synchronous condenser and SVC are controlled according to the grid voltage conditions. This mainly includes SVC coordinated control, synchronous condenser control, and steady-state capacitor-reactor control, as detailed below:

[0052] 1) After a DC fault, if the grid voltage is detected to be less than the threshold V fail If no DC blocking signal is detected, then DC commutation fails. During the period of DC commutation failure (T... i ,T i +T set Send a shutdown signal to the SVC when the measured grid voltage is not less than the threshold V. fail And the duration (the grid voltage is not less than the threshold V) failThe duration is not less than the threshold T com Send a recovery signal to the SVC; where T i T is the start time of the first commutation failure. set The duration of L consecutive DC commutation failures, where L is the preset number of failures, which is generally 3 times in engineering practice.

[0053] 2) such as Figure 2 As shown, under normal operating conditions, the synchronous condenser operates in constant reactive power control mode; during the transient process after a fault, if a grid overvoltage is detected, i.e., U≤U set2 And t≥t set2 Then the synchronous condenser will still operate in the constant reactive power control mode; where U is the grid voltage, t is the duration of U, and U set1 t is the threshold value for judging transient overvoltages that may cause new energy sources to disconnect from the grid. set2 For U set1 Duration, (U set1 ,t set1 It is usually determined by the characteristics of new energy sources.

[0054] 3) such as Figure 2 As shown, during the steady-state recovery period after a DC fault is cleared, the grid voltage drops after adjustment by a synchronous condenser. If U ≤ U set2 And t≥t set2 Then, a mode adjustment command is sent to the synchronous condenser to make it operate in a constant reactive power control mode, where the reactive power of the synchronous condenser is U = U set2 And t = t set2 The reactive power output of the time; if the reactive power output of the time-regulating camera equals the lower limit of reactive power output Q. con,min (Generally negative, indicating reactive power absorption), and U > U set2 Then, the nearby capacitor bank is disconnected or the reactor is connected in stages until the grid voltage is controlled within the normal range; where U is the grid voltage, t is the duration of U, and U set2 t represents the upper limit of voltage during normal operation of the power grid. set2 For U set2 The duration.

[0055] Finally, based on the established strategy, reactive power source control of the power grid is implemented, thereby suppressing power grid overvoltage.

[0056] With the large-scale integration of new energy sources into the grid, it is necessary to control the grid voltage to avoid large-scale disconnection of new energy sources due to transient overvoltage after DC faults. Dynamic reactive power sources such as SVCs and synchronous condensers in the grid can effectively regulate transient overvoltages. However, SVCs have a delay characteristic when DC commutation failure occurs, which may lead to more severe overvoltages. Therefore, in order to give full play to the role of SVCs, synchronous condensers, and capacitor reactors, the above-mentioned method starts from different time series of voltage control after faults, such as the transient overvoltage stage, the recovery stage after safety control actions, and the quasi-steady-state voltage recovery stage. It fully utilizes the transient regulation capabilities of SVCs and synchronous condensers, reduces the switching of capacitor reactors, and achieves full-process control of overvoltage after DC faults in the grid by coordinating the control of reactive power sources such as SVCs, synchronous condensers, and capacitor reactors. This solves the overvoltage problem after faults in high-proportion new energy DC transmission systems and improves the overall control level of grid voltage.

[0057] Based on the same technical solution, this invention also discloses a software system for the above-mentioned method, namely a coordinated control system for suppressing power grid overvoltage, comprising:

[0058] Replacement Quantity Calculation Module: Based on the DC fault set that causes overvoltage disconnection of new energy and the calculation model of maximum steady-state replacement quantity of synchronous condenser, calculate the maximum steady-state replacement quantity of synchronous condenser under each fault in the DC fault set, and take the minimum value among the maximum steady-state replacement quantities of synchronous condenser as the steady-state replacement quantity of synchronous condenser.

[0059] The calculation model for the maximum steady-state permutation of the synchronous condenser satisfies the following constraints:

[0060]

[0061] Among them, Q flt Q represents the total reactive power of the AC filter bank and DC reactive power compensation capacitor bank in the converter station of the DC reactive power compensation system. con Q is the reactive power generated by the synchronous condenser in steady state. ac The reactive power provided by the AC power grid system, Q dc N represents the reactive power consumed during DC power transmission, where n is the total number of AC filter banks and DC reactive power compensation capacitor banks in the converter station. flt,min V represents the minimum number of AC filter banks at the converter station corresponding to the operating range where the DC transmission power is located. i,min V is the voltage of the i-th node in the power grid. i The lower limit, V i,max V is the voltage of the i-th node in the power grid. i The upper limit of Q j,min The steady-state reactive power output Q of the j-th reactive power source in the power grid j Lower limit, Q j,max The steady-state reactive power output Q of the j-th reactive power source in the power grid j Upper limit.

[0062] Strategy Construction Module: Based on the grid voltage and the steady-state commutation of the synchronous condenser, a reactive power source control strategy to suppress grid overvoltage is constructed. The reactive power source control strategy is as follows: SVC coordinated control is triggered based on the grid voltage trajectory after DC commutation failure; in the case of grid overvoltage, the synchronous condenser is added to the DC reactive power compensation system, and the synchronous condenser is controlled according to the grid voltage.

[0063] Reactive power source control strategies include:

[0064] After a DC fault, if the grid voltage is detected to be less than the threshold V fail If no DC blocking signal is detected, DC commutation fails. During the DC commutation failure period, a shutdown signal is sent to the SVC. When the measured grid voltage is not less than the threshold V... fail And the duration is not less than the threshold T com Send a recovery signal to the SVC;

[0065] During the transient process following a DC fault, if an overvoltage is detected in the power grid, a mode adjustment command is sent to the synchronous condenser to make it operate in constant voltage control mode; if no overvoltage is detected in the power grid, a mode adjustment command is sent to the synchronous condenser to make it operate in constant reactive power control mode.

[0066] During the steady-state recovery period after a DC fault is cleared, the grid voltage drops after adjustment by a synchronous condenser. If U≤U set2 And t≥t set2 Then, a mode adjustment command is sent to the synchronous condenser to make it operate in a constant reactive power control mode, where the reactive power of the synchronous condenser is U = U set2 And t = t set2 The reactive power output of the time; if the reactive power output of the time-regulating camera equals the lower limit of reactive power output, and U > U set2 Then, the nearby capacitor bank is disconnected or the reactor is connected in stages until the grid voltage is controlled within the normal range; where U is the grid voltage, t is the duration of U, and U set2 t represents the upper limit of voltage during normal operation of the power grid. set2 For U set2 The duration.

[0067] Control module: Performs reactive power control of the power grid according to the reactive power control strategy to suppress power grid overvoltage.

[0068] Based on the same technical solution, the present invention also discloses a computer-readable storage medium storing one or more programs, the one or more programs including instructions that, when executed by a computing device, cause the computing device to perform a coordinated control method for suppressing power grid overvoltage.

[0069] Based on the same technical solution, the present invention also discloses a computing device, including one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for executing a coordinated control method for suppressing grid overvoltage.

[0070] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0071] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations 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, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0072] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0073] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0074] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A coordinated control method for suppressing power grid overvoltage, characterized in that, include: Based on the DC fault set that causes overvoltage grid disconnection of new energy sources and the calculation model of the maximum steady-state displacement of synchronous condensers, the steady-state displacement of synchronous condensers is calculated. Based on the grid voltage and the steady-state commutation of the synchronous condenser, a reactive power source control strategy to suppress grid overvoltage is constructed. The reactive power source control strategy is as follows: SVC coordinated control is triggered based on the grid voltage trajectory after DC commutation failure; in the case of grid overvoltage, the synchronous condenser is added to the DC reactive power compensation system, and the synchronous condenser and SVC are controlled according to the grid voltage. Power grid reactive power control is carried out according to reactive power control strategies to suppress power grid overvoltage. The above-mentioned reactive power source control strategies include: After a DC fault, if the grid voltage is detected to be less than a threshold V fail and no DC blocking signal is detected, a DC commutation failure is detected, during which a shutdown signal is sent to the SVC, and when the grid voltage is detected to be not less than the threshold V fail and the duration is not less than a threshold T com , a resume signal is sent to the SVC. During the transient process following a DC fault, if an overvoltage is detected in the power grid, a mode adjustment command is sent to the synchronous condenser to make it operate in constant voltage control mode; if no overvoltage is detected in the power grid, a mode adjustment command is sent to the synchronous condenser to make it operate in constant reactive power control mode. During the steady-state recovery after DC fault clearing, the grid voltage is adjusted by the phase modifier. If U≤U set2 and t≥t set2 , a mode adjustment instruction is sent to the phase modifier, so that the phase modifier operates in the constant reactive power control mode, and the reactive power of the phase modifier is U=U set2 and t=t set2 . If the reactive power output of the phase modifier is equal to the lower limit of the reactive power output, and U>U set2 , the near-zone capacitor banks are removed or the reactors are put in by turns until the grid voltage is controlled within the normal range. Wherein, U is the grid voltage, t is the duration of U, U set2 is the upper limit of the voltage during normal operation of the grid, and t set2 is the duration of U set2 .

2. The coordinated control method for suppressing power grid overvoltage according to claim 1, characterized in that, Based on the DC fault set causing overvoltage grid disconnection of new energy sources and the calculation model of the maximum steady-state displacement of the synchronous condenser, the steady-state displacement of the synchronous condenser is calculated, including: Based on the DC fault set that causes overvoltage disconnection of new energy and the calculation model of the maximum steady-state displacement of synchronous condensers, the maximum steady-state displacement of synchronous condensers under each fault in the DC fault set is calculated, and the minimum value among the maximum steady-state displacements of synchronous condensers is taken as the steady-state displacement of synchronous condensers.

3. The coordinated control method for suppressing power grid overvoltage according to claim 1 or 2, characterized in that, The calculation model for the maximum steady-state permutation of the synchronous condenser satisfies the following constraints: Among them, Q flt Q represents the total reactive power of the AC filter bank and DC reactive power compensation capacitor bank in the converter station of the DC reactive power compensation system. con Q is the reactive power generated by the synchronous condenser in steady state. ac The reactive power provided by the AC power grid system, Q dc N represents the reactive power consumed during DC power transmission, and n represents the total number of remaining filter banks and capacitor banks in the DC reactive power compensation system after the replacement. flt,min V represents the minimum number of AC filter banks at the converter station corresponding to the operating range where the DC transmission power is located. i,min V is the voltage of the i-th node in the power grid. i The lower limit, V i,max V is the voltage of the i-th node in the power grid. i The upper limit of Q j,min The steady-state reactive power output Q of the j-th reactive power source in the power grid j Lower limit, Q j,max The steady-state reactive power output Q of the j-th reactive power source in the power grid j Upper limit.

4. A coordinated control system for suppressing power grid overvoltage, characterized in that, include: Replacement Quantity Calculation Module: Based on the DC fault set that causes overvoltage disconnection of new energy and the calculation model of the maximum steady-state replacement quantity of the synchronous condenser, calculate the steady-state replacement quantity of the synchronous condenser; Strategy Construction Module: Based on the grid voltage and the steady-state commutation of the synchronous condenser, a reactive power source control strategy to suppress grid overvoltage is constructed. The reactive power source control strategy is as follows: SVC coordinated control is triggered based on the grid voltage trajectory after DC commutation failure; in the case of grid overvoltage, the synchronous condenser is added to the DC reactive power compensation system, and the synchronous condenser and SVC are controlled according to the grid voltage. Control module: Performs reactive power control of the power grid according to the reactive power control strategy to suppress power grid overvoltage; The above-mentioned reactive power source control strategies include: After a DC fault, if the grid voltage is detected to be less than the threshold V fail If no DC blocking signal is detected, DC commutation fails. During the DC commutation failure period, a shutdown signal is sent to the SVC. When the measured grid voltage is not less than the threshold V... fail And the duration is not less than the threshold T com Send a recovery signal to the SVC; During the transient process following a DC fault, if an overvoltage is detected in the power grid, a mode adjustment command is sent to the synchronous condenser to make it operate in constant voltage control mode; if no overvoltage is detected in the power grid, a mode adjustment command is sent to the synchronous condenser to make it operate in constant reactive power control mode. During the steady-state recovery period after a DC fault is cleared, the grid voltage drops after adjustment by a synchronous condenser. If U≤U set2 And t≥t set2 Then, a mode adjustment command is sent to the synchronous condenser to make it operate in a constant reactive power control mode, where the reactive power of the synchronous condenser is U = U set2 And t = t set2 The reactive power output of the time; if the reactive power output of the time-regulating camera equals the lower limit of reactive power output, and U > U set2 Then, the nearby capacitor bank is disconnected or the reactor is connected in stages until the grid voltage is controlled within the normal range; where U is the grid voltage, t is the duration of U, and U set2 t represents the upper limit of voltage during normal operation of the power grid. set2 For U set2 The duration.

5. A coordinated control system for suppressing power grid overvoltage according to claim 4, characterized in that, Replacement Quantity Calculation Module: Based on the DC fault set that causes overvoltage disconnection of new energy and the calculation model of maximum steady-state replacement quantity of synchronous condenser, calculate the maximum steady-state replacement quantity of synchronous condenser under each fault in the DC fault set, and take the minimum value among the maximum steady-state replacement quantities of synchronous condenser as the steady-state replacement quantity of synchronous condenser.

6. The coordinated control system for suppressing power grid overvoltage according to claim 4 or 5, characterized in that, The calculation model for the maximum steady-state permutation of the synchronous condenser satisfies the following constraints: Among them, Q flt Q represents the total reactive power of the AC filter bank and DC reactive power compensation capacitor bank in the converter station of the DC reactive power compensation system. con Q is the reactive power generated by the synchronous condenser in steady state. ac The reactive power provided by the AC power grid system, Q dc N represents the reactive power consumed during DC power transmission, and n represents the total number of remaining filter banks and capacitor banks in the DC reactive power compensation system after the replacement. flt,min V represents the minimum number of AC filter banks at the converter station corresponding to the operating range where the DC transmission power is located. i,min V is the voltage of the i-th node in the power grid. i The lower limit, V i,max V is the voltage of the i-th node in the power grid. i The upper limit of Q j,min The steady-state reactive power output Q of the j-th reactive power source in the power grid j Lower limit, Q j,max The steady-state reactive power output Q of the j-th reactive power source in the power grid j Upper limit.

7. A computer-readable storage medium for storing one or more programs, characterized in that: The one or more programs include instructions that, when executed by a computing device, cause the computing device to perform any of the methods according to claims 1 to 3.

8. A computing device, characterized in that, include: One or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, the one or more programs including instructions for performing any of the methods according to claims 1 to 3.

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