A protection signal trigger response driven emergency control method and system

Abstract

The present invention discloses an emergency control method driven by protection signal trigger response, including obtaining key sections and short-circuit type fault sets that may cause the power grid to enter isolated network operation and the transient voltage to recover slowly; monitoring the main protection phase tripping signal and current and power real-time operation information of the key sections. If the phase tripping information is received and the sudden change quantity is met to start, the emergency control device will act according to the preset offline control strategy. After the action, the voltage of the isolated network system site is monitored in real time. If the voltage is too high, the emergency control is used to supplement the capacitor group to maintain the system voltage back to a reasonable operating range. Relying on the triggering of the relay protection signal, the sudden change quantity of the electrical quantity is taken as the anti-misjudgment criterion, and the emergency control action time is shortened from the traditional 300ms to about 200ms. Within the time window of 5s of an emergency control action cycle, the voltage response drive is integrated and the capacitor supplementation measure is added, which is conducive to controlling the steady-state voltage to return to a reasonable operating range as soon as possible.

Description

Technical Field

[0001] The present invention belongs to the field of power systems and automation technologies, and relates to an emergency control method and system driven by a protection signal trigger response, and specifically to a transient low-voltage and high-frequency steady-state high-voltage and low-frequency control method and system for a power grid. Background Art

[0002] There are still many local power grids in the western or southwestern parts of China that are generally connected to the main grid through 1-2 interconnection channels. The interconnection channels are mostly single-circuit lines or double-circuit lines on the same pole. Due to the weak grid structure or harsh climate and geological conditions, the risk of disconnection of the interconnection channels is relatively high. After disconnection, the local power grid switches to isolated grid operation. Due to the small inertia of the isolated grid, the weak dynamic reactive power support capacity, and the high proportion of motors in the local grid load, the isolated system is prone to transient low voltage and high frequency (transient voltage is lower than 0.75pu for more than 1s, and the transient frequency is generally higher than 51.0Hz) and steady-state high voltage and low frequency (steady-state voltage can generally be higher than 1.07pu, and the frequency is often lower than 49.0Hz), which brings huge challenges to the operation and control of the power grid.

[0003] The local power grid contains numerous motor loads powered by VFDs. The system transient voltage dropped below 0.75 pu for over 1 second, triggering trips on both the VFD and motor undervoltage protection. Furthermore, a transient frequency exceeding 51.0 Hz could trigger the high-frequency protection of the network's generators, further escalating the incident. Emergency control, with equal or omitted load shedding, does not address the system's transient low voltage and high frequency phenomenon. This also does not address the system's slow transient voltage recovery. Excessive load shedding, while accelerating transient voltage recovery, can lead to subsequent high-frequency issues. Regarding the steady-state high voltage and low frequency issue caused by transient voltage recovery, if emergency control simultaneously removes reactive power compensation when removing loads, this can increase reactive power imbalance during the transient voltage dip and even cause voltage instability. Directly shedding additional loads based on the power balance principle based on the overvoltage and low frequency phenomenon will not only exacerbate the high voltage issue, but the amount of additional load shedding cannot be quantified. Removing generators will exacerbate the low frequency issue. This makes traditional emergency control methods such as active power control such as generator shedding and load shedding ineffective for transient low-voltage and high-frequency and steady-state low-voltage and high-frequency problems. Summary of the Invention

[0004] To address the above problems, the present invention proposes an emergency control method and system driven by a fusion response triggered by a protection signal, which can resolve the transient low-voltage and high-frequency and steady-state high-voltage and low-frequency problems of the power grid, and improve the reliability of the power grid safety and stability control measures.

[0005] In order to achieve the above technical objectives, the technical solutions adopted by the present invention are as follows:

[0006] In a first aspect, a protection signal trigger response driven emergency control method is provided, comprising:

[0007] Obtain the key disconnecting sections and fault type sets that may cause the power grid to enter isolated operation locally or as a whole, and where the isolated grid system has slow transient voltage recovery;

[0008] Obtain the load shedding threshold value set M{Pmk1, Pmk2} of the capacitor bank to be supplemented and shelved; after the section short-circuit fault emergency control shedding loads Pmk1 and Pmk2 according to priority, the voltage at the isolated grid site recovers to k1 and k2, respectively, and the duration is greater than t3;

[0009] Obtain the sites where capacitor banks need to be supplemented and the corresponding capacitor capacity set C{(B1,C B11 ,1),(B1,C B12 ,2),……(Bn,C Bn1 ,1),(Bn,C Bn2 ,2)}, for each substation Bn that needs to cut capacitors, the cut capacitor capacity is divided into two levels, namely the first level cut capacity C Bn1 and the second-level resection capacity C Bn2 , forming a preset capacitor compensation strategy table;

[0010] Obtain real-time monitoring of key section main protection phase tripping signals and electrical quantity operation information;

[0011] Based on the key breaking section and fault type set, the key section main protection phase tripping signal and the electrical quantity operation information, it is determined whether the emergency control start condition is met, and if so, the preset offline control strategy is searched for to perform emergency control;

[0012] During one control cycle of emergency control, the voltage information of key sites in the isolated grid system is monitored in real time. Based on the voltage information and the load shedding threshold value set M of the capacitor bank to be supplemented and cut, the sites of the capacitor bank to be supplemented and cut, and the corresponding capacitor capacity set C, it is determined whether the steady-state voltage of the key site of the isolated grid system is too high and the amount of load removed is greater than the capacitor cutting threshold value. If so, the corresponding capacitor bank is supplemented and cut according to the preset capacitor cutting strategy table.

[0013] In some embodiments, obtaining a set of key disconnecting sections and fault types that may cause a part of the power grid or the entire power grid to enter an isolated grid operation and cause a slow transient voltage recovery of the isolated grid system includes:

[0014] Based on the electromechanical simulation data of the power grid, a typical minimum startup mode of conventional units was selected. The simulation analysis obtained the key section disconnection and fault type set Q{(L1,F1),(L1,F2),(L2,F1)…(Ln,Fn)} that caused the local or entire power grid system to enter the isolated network operation and caused the transient voltage of the isolated network system to recover slowly. Among them, Ln is the key disconnection section and Fn is the fault type.

[0015] The disconnected section fault set includes: line N-1 disconnected, and line N-2 on the same pole disconnected;

[0016] The fault types include: single-phase short circuit fault, two-phase short circuit fault, two-phase short circuit grounding fault, and three-phase short circuit grounding fault.

[0017] In some embodiments, the transient voltage recovery slowness judgment standard is 0.75 pu, 1 s.

[0018] In some embodiments, based on the key breaking section and fault type set, the key section main protection phase tripping signal and the electrical quantity operation information, it is determined whether the emergency control start condition is met. If so, a preset offline control strategy is searched for to perform emergency control; including:

[0019] In response to receiving a phase protection trip signal, determining whether it belongs to a critical breaking section and a fault type set Q;

[0020] In response to this, it is determined whether the real-time electrical quantity of the key section meets any of the following mutation criteria:

[0021] 1) Startup by current mutation: △i≥△is, where △i is the instantaneous current mutation and △is is the preset value for starting the instantaneous current mutation;

[0022] 2) Power sudden change start: △P ≥ △Ps, where △P is the power sudden change and △Ps is the power sudden change start preset value;

[0023] In response to determining that the real-time electrical quantity of the key section meets any of the mutation criteria, emergency control is initiated: the emergency control device performs control according to the preset offline control strategy, and records the load removal quantity Pl and the emergency control start time t1.

[0024] In some embodiments, the method for obtaining the preset offline control strategy includes:

[0025] Based on the electromechanical simulation data of the power grid, various typical operating modes of the power grid are selected. Based on the operating flow range of the key section, simulation calculations are performed to obtain the load shedding amount Pl that the emergency control system can restore the safe and stable power grid when the key section is disconnected, and a preset offline control strategy is formed.

[0026] In some embodiments, a method for obtaining sites requiring capacitor bank removal and corresponding capacitor capacity set C includes:

[0027] Based on the electromechanical simulation data of the power grid, the typical minimum startup mode of conventional units is selected, and the sensitivity of the capacitor removal capacity at different sites in the isolated grid system to the voltage recovery of the monitoring site is calculated through simulation, and the sites that need to supplement the capacitor group and the corresponding capacitor removal capacity set C{(B1,C B11 ,1),(B1,C B12 ,2),……(Bn,C Bn1 ,1),(Bn,C Bn2 ,2)}, for each substation Bn that needs to cut capacitors, the cut capacitor capacity is divided into two levels, namely the first level cut capacity C Bn1 and the second-level resection capacity C Bn2 , and form a preset capacitor compensation strategy table.

[0028] In some embodiments, a method for obtaining a load shedding threshold value set M for capacitor groups requiring additional shedding includes: based on power grid electromechanical simulation data, selecting a typical minimum startup mode for conventional units, simulating and analyzing the section short-circuit fault disconnection emergency control to shedding different amounts of load according to priority, and the voltage at the isolated grid system site recovers to k1 and k2 respectively, and the duration is greater than t3, and the load shedding amounts are recorded as Pmk1 and Pmk2, and a capacitor shedding threshold value set M{Pmk1, Pmk2} is formed.

[0029] In some embodiments, during a control cycle of emergency control, voltage information at key sites in the isolated grid system is monitored in real time. Based on the voltage information, a set M of load shedding thresholds for capacitor banks requiring supplemental shedding, sites requiring supplemental shedding, and a corresponding set C of capacitor capacities, it is determined whether the steady-state voltage at the key sites in the isolated grid system is too high and the amount of load shedding is greater than the capacitor shedding threshold. If so, the corresponding capacitor banks are supplemented according to a preset capacitor shedding strategy table, including:

[0030] Real-time monitoring of voltage information at key sites within the isolated grid system;

[0031] In response to the critical site voltage U>k1 or U>k2, if either condition is met, the time is recorded as t2, t2-t1<5s, where t1 is the emergency control start time; compare whether the removed load amount Pl is greater than the value in the capacitor threshold value set M{Pmk1,Pmk2};

[0032] In response to Pmk2>Pl>Pmk1, the first level of cut-off capacity C in the corresponding cut-off capacitor capacity set C is selected according to the site where the capacitor bank needs to be cut off. Bn1 Cut off the corresponding capacitor group;

[0033] In response to Pl>Pmk2, the second level of cut-off capacity C in the corresponding cut-off capacitor capacity set C is selected according to the site where the capacitor bank needs to be cut off. Bn2 Remove the corresponding capacitor bank.

[0034] In some embodiments, k1 is 1.07 pu and k2 is 1.10 pu.

[0035] In a second aspect, the present invention provides an emergency control system driven by a protection signal trigger response, comprising a processor and a storage medium;

[0036] The storage medium is used to store instructions;

[0037] The processor is configured to operate according to the instructions to execute the steps of the method according to the first aspect.

[0038] In a third aspect, the present invention provides a storage medium having a computer program stored thereon, which implements the steps of the method described in the first aspect when executed by a processor.

[0039] Beneficial effects of the present invention:

[0040] The present invention proposes introducing the main protection signal of the key section as the starting criterion for emergency control, using the sudden change information of the section electrical quantity as the anti-false judgment criterion, and reducing the control time of the line tripping and load shedding measures from 320ms to about 200ms. This effectively solves the transient low voltage and high frequency problem caused by the high proportion of induction motors, facilitates the rapid recovery of the system transient voltage after a short circuit fault, and also avoids premature removal of the capacitor bank, which aggravates the transient voltage drop. Within the time window of an emergency control action cycle of 5s, the voltage response drive is integrated and the capacitor shedding measure is added. This helps to control the steady-state voltage to return to a reasonable operating range as soon as possible, solves the low frequency problem caused by overvoltage, and solves the steady-state high voltage and low frequency problem with a very low control cost. Drawing on the characteristic of relying on electrical quantity response drive in correction control, the system voltage is judged in real time and the capacitor bank is shelved within an emergency control action cycle, effectively solving the steady-state high voltage and low frequency problem caused by the removal of a large number of low power factor loads. It not only avoids the accelerated system voltage drop caused by synchronous capacitor removal, but also does not incur additional control cost. A new emergency control action mechanism triggered by relay protection signals and driven by voltage response has a good control effect on the voltage-frequency coupling phenomenon in the local power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The embodiment of the present invention provides an emergency control method process for dealing with transient low voltage and high frequency and steady-state high voltage and low frequency. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0043] The application principle of the present invention is described in detail below with reference to the accompanying drawings.

[0044] Example 1

[0045] An emergency control method driven by a protection signal trigger response, comprising:

[0046] Obtain the key disconnecting sections and fault type sets that may cause the power grid to enter isolated operation locally or as a whole, and where the isolated grid system has slow transient voltage recovery;

[0047] Obtain the load shedding threshold value set M{Pmk1, Pmk2} of the capacitor bank to be supplemented and shelved; after the section short-circuit fault emergency control shedding loads Pmk1 and Pmk2 according to priority, the voltage at the isolated grid site recovers to k1 and k2, respectively, and the duration is greater than t3;

[0048] Obtain the sites where capacitor banks need to be supplemented and the corresponding capacitor capacity set C{(B1,C B11 ,1),(B1,C B12 ,2),……(Bn,C Bn1 ,1),(Bn,C Bn2 ,2)}, for each substation Bn that needs to cut capacitors, the cut capacitor capacity is divided into two levels, namely the first level cut capacity C Bn1 and the second-level resection capacity C Bn2 , forming a preset capacitor compensation strategy table;

[0049] Obtain real-time monitoring of key section main protection phase tripping signals and electrical quantity operation information;

[0050] Based on the key breaking section and fault type set, the key section main protection phase tripping signal and the electrical quantity operation information, it is determined whether the emergency control start condition is met, and if so, the preset offline control strategy is searched for to perform emergency control;

[0051] During one control cycle of emergency control, the voltage information of key sites in the isolated grid system is monitored in real time. Based on the voltage information and the load shedding threshold value set M of the capacitor bank to be supplemented and cut, the sites of the capacitor bank to be supplemented and cut, and the corresponding capacitor capacity set C, it is determined whether the steady-state voltage of the key site of the isolated grid system is too high and the amount of load removed is greater than the capacitor cutting threshold value. If so, the corresponding capacitor bank is supplemented and cut according to the preset capacitor cutting strategy table.

[0052] The power grid described in the embodiments of the present invention generally has a small system inertia and a weak grid structure. Before a fault occurs, power is received through the fault section. The specific implementation process of obtaining the key disconnecting section and the fault type set Q is as follows:

[0053] Based on power grid electromechanical simulation data, a typical minimum startup scenario for conventional generators was selected. Simulation analysis was performed on a fault set consisting of disconnecting line N-1 and disconnecting line N-2 on the same pole, as well as fault types such as single-phase short circuit, two-phase short circuit, two-phase short-circuit to ground fault, and three-phase short-circuit to ground fault. This analysis identified the critical disconnection sections and fault type set Q{(L1, F1), (L1, F2), (L2, F1)…(Ln, Fn)} that cause the grid to enter isolated operation locally or as a whole, and slow transient voltage recovery in the isolated system. Ln represents the critical disconnection section, and Fn refers to the fault type. Multiple fault types, such as F1…Fn, may exist, leading to slow transient voltage recovery when disconnecting this section. The disconnection section fault set includes disconnecting line N-1 and disconnecting line N-2 on the same pole. The criterion for slow transient voltage recovery is generally 0.75 pu, 1 s.

[0054] The conventional minimum startup mode generally refers to the minimum startup mode of conventional units that meet the active power balance and reactive power voltage control requirements of the power grid and operate normally.

[0055] In some embodiments, based on the key breaking section and fault type set, the key section main protection phase tripping signal and the electrical quantity operation information, it is determined whether the emergency control start condition is met. If so, a preset offline control strategy is searched for to perform emergency control; including:

[0056] In response to receiving a phase protection trip signal, determining whether it belongs to a critical breaking section and a fault type set Q;

[0057] In response to this, it is determined whether the real-time electrical quantity of the key section meets any of the following mutation criteria:

[0058] 1) Startup by current mutation: △i≥△is, where △i is the instantaneous current mutation and △is is the preset value for starting the instantaneous current mutation;

[0059] 2) Power sudden change start: △P ≥ △Ps, where △P is the power sudden change and △Ps is the power sudden change start preset value;

[0060] In response to determining that the real-time electrical quantity of the key section meets any of the mutation criteria, emergency control is initiated: the emergency control device performs control according to the preset offline control strategy, and records the load removal quantity Pl and the emergency control start time t1.

[0061] The offline control strategy implementation process of emergency control is as follows:

[0062] Based on the electromechanical simulation data of the power grid, various typical operating modes of the power grid are selected. Based on the operating flow range of the key section, simulation calculations are performed to obtain the load shedding amount that the emergency control system can use to restore the safe and stable power grid when the key section is disconnected, and an offline strategy control table for the disconnection of the key section is formed.

[0063] It is also necessary to obtain the key sites of the off-grid system, the capacitor cutting threshold value set M, and the capacitor cutting strategy table. The implementation process is as follows:

[0064] Based on the electromechanical simulation data of the power grid, the typical minimum startup method of conventional units is selected, and the key sites in the isolated grid system that is disconnected from the grid are obtained through simulation. Generally, more important hub sites are selected, and their voltage information is monitored in real time.

[0065] Based on the electromechanical simulation data of the power grid, the typical minimum startup mode of conventional units is selected, and the sensitivity of the capacitor removal capacity at different sites in the isolated grid system to the voltage recovery of the monitoring site is calculated through simulation, and the sites that need to supplement the capacitor group and the corresponding capacitor removal capacity set C{(B1,C B11 ,1),(B1,C B12 ,2),……(Bn,C Bn1 ,1),(Bn,C Bn2 ,2)}, for each substation Bn that needs to cut capacitors, the cut capacitor capacity is divided into two levels, and the cut capacity of each level is C Bn1 and C Bn2 , and form a preset capacitor compensation strategy table.

[0066] Based on the electromechanical simulation data of the power grid, a typical minimum startup mode of conventional units is selected. The simulation analysis shows that after the emergency control of section short-circuit fault disconnection removes different amounts of load according to priority, the voltage of the isolated grid site recovers to k1 and k2 respectively, and the load removal amount Pmk1 and Pmk2 at the time of duration greater than t3, and the threshold value set M{Pmk1, Pmk2} of the capacitor is formed.

[0067] In some embodiments, during a control cycle of emergency control, voltage information at key sites in the isolated grid system is monitored in real time. Based on the voltage information, a set M of load shedding thresholds for capacitor banks requiring supplemental shedding, sites requiring supplemental shedding, and a corresponding set C of capacitor capacities, it is determined whether the steady-state voltage at the key sites in the isolated grid system is too high and the amount of load shedding is greater than the capacitor shedding threshold. If so, the corresponding capacitor banks are supplemented according to a preset capacitor shedding strategy table, including:

[0068] Real-time monitoring of voltage information at key sites within the isolated grid system;

[0069] In response to the critical site voltage U>k1 or U>k2, if either condition is met, the time is recorded as t2, t2-t1<5s, where t1 is the emergency control start time; compare whether the removed load amount Pl is greater than the value in the capacitor threshold value set M{Pmk1,Pmk2};

[0070] In response to Pmk2>Pl>Pmk1, the first level of cut-off capacity C in the corresponding cut-off capacitor capacity set C is selected according to the site where the capacitor bank needs to be cut off. Bn1 Cut off the corresponding capacitor group;

[0071] In response to Pl>Pmk2, the second level of cut-off capacity C in the corresponding cut-off capacitor capacity set C is selected according to the site where the capacitor bank needs to be cut off. Bn2 Remove the corresponding capacitor bank.

[0072] k1 can be 1.07pu, k2 can be 1.10pu, or specified by the user.

[0073] Example 2

[0074] In a second aspect, the present invention provides an emergency control system driven by a protection signal trigger response, comprising a processor and a storage medium;

[0075] The storage medium is used to store instructions;

[0076] The processor is configured to operate according to the instructions to execute the steps of the method described in Example 1.

[0077] This example introduces an emergency control system driven by a fusion response triggered by protection signals, including:

[0078] The data storage module is used to store the key disconnection sections and fault type set Q that cause the power grid to enter isolated network operation, store the offline control strategy for dealing with various section disconnections; store the key voltage site set in the isolated network system; store the capacitor cutting threshold value set M that causes steady-state high voltage in the isolated network system; store the sites and cut-off capacity set C that need to cut capacitor groups in the isolated network system; and store the emergency control cutting capacitor group control strategy.

[0079] The real-time data acquisition module is used to monitor the real-time electrical quantity information of various sections; the real-time monitoring of the main protection phase tripping information of key sections; and the real-time monitoring of the real-time voltage information of key stations.

[0080] The logic judgment module is used to determine whether the stored critical section disconnection and fault type fault set are met; to determine whether the sudden change quantity criterion is met; to determine whether the load removal amount is greater than the capacitor compensation threshold; to determine whether the site voltage is too high;

[0081] Control Module

[0082] It is used to select an offline strategy from the stored offline strategy table for emergency control based on the main protection tripping information and real-time electrical quantity information; it is used to control the capacitor bank from the stored capacitor cutting strategy based on the voltage and time information of key sites and the amount of load removed.

[0083] In this example, the data storage module is used to:

[0084] Based on power grid electromechanical simulation data, a typical minimum startup method for conventional units was selected. Simulation analysis was performed to identify and store the critical disconnection sections and fault type set Q{(L1, F1), (L1, F2), (L2, F1)…(Ln, Fn)} that cause the grid to enter isolated operation locally or as a whole, and slow transient voltage recovery in the isolated system. Ln represents the critical disconnection section, and Fn represents the fault type. Disconnection section faults include: line N-1 disconnected, and line N-2 on the same pole disconnected. Fault types include: single-phase short circuit fault, two-phase short circuit fault, two-phase short circuit to ground fault, and three-phase short circuit to ground fault. The transient voltage recovery slowness standard is generally 0.75 pu, 1 s.

[0085] Based on the electromechanical simulation data of the power grid, various typical operating modes of the power grid are selected. Based on the operating flow range of the key section, the simulation calculation is carried out to obtain the load shedding amount that the emergency control system can restore the safe and stable power grid when the key section is disconnected, and an offline strategy control table is formed and stored.

[0086] Based on the grid electromechanical simulation data, a typical minimum startup method for conventional units is selected. The key sites within the isolated grid system are obtained and stored. Generally, more important hub sites are selected.

[0087] Based on the electromechanical simulation data of the power grid, a typical minimum startup mode of conventional units is selected. The simulation analysis shows that after the emergency control of section short-circuit fault disconnection cuts off different amounts of load according to priority, the voltage of the isolated grid site recovers to k1 and k2 respectively, and the load removal amount Pmk1 and Pmk2 at the time of duration greater than t3 is achieved. A set of capacitor cutting threshold values M{Pmk1, Pmk2} is formed and stored.

[0088] Based on the electromechanical simulation data of the power grid, the typical minimum startup mode of conventional units is selected, and the sensitivity of the capacitor removal capacity at different sites in the isolated grid system to the voltage recovery of the monitoring site is calculated through simulation, and the sites that need to supplement the capacitor group and the corresponding capacitor removal capacity set C{(B1,C B11 ,1),(B1,C B12 ,2),……(Bn,C Bn1 ,1),(Bn,C Bn2,2)}, for each substation Bn that needs to cut capacitors, the cut capacitor capacity is divided into two levels, and the cut capacity of each level is C Bn1 and C Bn2 , and form a preset capacitor compensation strategy table and store it.

[0089] In this example, the real-time data acquisition module is specifically used to:

[0090] Real-time monitoring of electrical quantity information and main protection phase tripping information of each key section; real-time monitoring of voltage information of each key site in the isolated grid system;

[0091] In this example, the logic judgment module is specifically used for:

[0092] According to the monitored phase tripping information of the key section, it is determined whether the short-circuit fault type of the section belongs to the set Q.

[0093] Determine whether the mutation criterion is met based on the monitored real-time voltage and power electrical quantity information:

[0094] Startup due to sudden change of current: △i≥△is (△is is the starting constant value of sudden change of current instantaneous value);

[0095] Power sudden change start: △P≥△Ps (△Ps is the power sudden change start constant);

[0096] △is and △Ps can be determined according to the actual cross-section flow. These two start-up criteria are in an "OR" logical relationship. If any of the criteria is met, the device can enter the start-up state.

[0097] Used to determine whether the voltage at a key site in an isolated grid system is U>k1 or U>k2. If either condition is met, the time is recorded as t2, and t2-t1<5s. k1 can be 1.07pu, k2 can be 1.10pu, or can be specified by the user.

[0098] Used to determine the load size to be removed by the emergency control system, Pmk2>Pl>Pmk1 or Pl>Pmk2. If either condition is met, the capacitor bank is removed according to the preset capacitor bank removal strategy.

[0099] In this example, the control module is specifically used to:

[0100] Based on phase tripping information at key sections and combined with electrical quantity mutation information as a preventative measure, load shedding is implemented according to the pre-set offline control strategy. Within a control cycle, voltage information at key stations in the isolated grid is monitored. If the voltage at a station is too high, the capacitor bank is removed according to the pre-set capacitor bank switching strategy.

[0101] Example 3

[0102] In a third aspect, this embodiment provides a storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described in Example 1 are implemented.

[0103] 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 a complete hardware embodiment, a complete software embodiment, or an embodiment 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 magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0104] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes 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 steps in the process. 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.

[0105] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory 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 The function specified in one or more boxes.

[0106] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0107] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which are all protected by the present invention.

[0108] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. An emergency control method driven by a protection signal trigger response, characterized in that: include: Obtain the key disconnecting sections and fault type sets that may cause the power grid to enter isolated operation locally or as a whole, and where the isolated grid system has slow transient voltage recovery; Obtain the load shedding threshold value set M{Pmk1, Pmk2} of the capacitor bank to be supplemented and shelved; after the section short-circuit fault emergency control shedding loads Pmk1 and Pmk2 according to priority, the voltage at the isolated grid site recovers to k1 and k2, respectively, and the duration is greater than t3; Obtain the sites where capacitor banks need to be supplemented and the corresponding capacitor capacity set C{(B1,C B11 ,1),(B1,C B12 ,2),……(Bn,C Bn1 ,1),(Bn,C Bn2 ,2)}, for each substation Bn that needs to cut capacitors, the cut capacitor capacity is divided into two levels, namely the first level cut capacity C Bn1 and the second-level resection capacity C Bn2 , forming a preset capacitor compensation strategy table; Obtain real-time monitoring of key section main protection phase tripping signals and electrical quantity operation information; Based on the key breaking section and fault type set, the key section main protection phase tripping signal and the electrical quantity operation information, it is determined whether the emergency control start condition is met, and if so, the preset offline control strategy is searched for to perform emergency control; During one control cycle of emergency control, the voltage information of key sites in the isolated grid system is monitored in real time. Based on the voltage information and the load shedding threshold value set M of the capacitor bank to be supplemented and cut, the sites of the capacitor bank to be supplemented and cut, and the corresponding capacitor capacity set C, it is determined whether the steady-state voltage of the key site of the isolated grid system is too high and the amount of load removed is greater than the capacitor cutting threshold value. If so, the corresponding capacitor bank is supplemented and cut according to the preset capacitor cutting strategy table.

2. The emergency control method according to claim 1, characterized in that: Obtain the key disconnect sections and fault type sets that may cause the power grid to enter isolated operation locally or as a whole, and cause the transient voltage of the isolated system to recover slowly, including: Based on the electromechanical simulation data of the power grid, a typical minimum startup mode of conventional units was selected. The simulation analysis obtained the key section disconnection and fault type set Q{(L1,F1),(L1,F2),(L2,F1)…(Ln,Fn)} that caused the local or entire power grid system to enter the isolated network operation and caused the transient voltage of the isolated network system to recover slowly. Among them, Ln is the key disconnection section and Fn is the fault type. The disconnected section fault set includes: line N-1 disconnected, and line N-2 on the same pole disconnected; The fault types include: single-phase short circuit fault, two-phase short circuit fault, two-phase short circuit grounding fault, and three-phase short circuit grounding fault.

3. The emergency control method according to claim 1 or 2, characterized in that: The judgment standard for slow transient voltage recovery is 0.75pu, 1s.

4. The emergency control method according to claim 1, characterized in that: Based on the key breaking section and fault type set, the key section main protection phase tripping signal and the electrical quantity operation information, it is determined whether the emergency control start condition is met. If so, a preset offline control strategy is searched for to perform emergency control; including: In response to receiving a phase protection trip signal, determining whether it belongs to a critical breaking section and a fault type set Q; In response to this, it is determined whether the real-time electrical quantity of the key section meets any of the following mutation criteria: 1) Startup by current mutation: △i≥△is, where △i is the instantaneous current mutation and △is is the preset value for starting the instantaneous current mutation; 2) Power sudden change start: △P ≥ △Ps, where △P is the power sudden change and △Ps is the power sudden change start preset value; In response to determining that the real-time electrical quantity of the key section meets any of the mutation criteria, emergency control is initiated: the emergency control device performs control according to the preset offline control strategy, and records the load removal quantity Pl and the emergency control start time t1.

5. The emergency control method according to claim 1, characterized in that: The method for obtaining the preset offline control strategy includes: Based on the electromechanical simulation data of the power grid, various typical operating modes of the power grid are selected. Based on the operating flow range of the key section, simulation calculations are performed to obtain the load shedding amount Pl that the emergency control system can restore the safe and stable power grid when the key section is disconnected, and a preset offline control strategy is formed.

6. The emergency control method according to claim 1, characterized in that: The method for obtaining the sites requiring capacitor bank removal and the corresponding capacitor capacity set C includes: Based on the electromechanical simulation data of the power grid, the typical minimum startup mode of conventional units is selected, and the sensitivity of the capacitor removal capacity at different sites in the isolated grid system to the voltage recovery of the monitoring site is calculated through simulation, and the sites that need to supplement the capacitor group and the corresponding capacitor removal capacity set C{(B1,C B11 ,1),(B1,C B12 ,2),……(Bn,C Bn1 ,1),(Bn,C Bn2 ,2)}, for each substation Bn that needs to cut capacitors, the cut capacitor capacity is divided into two levels, namely the first level cut capacity C Bn1 and the second-level resection capacity C Bn2 , and form a preset capacitor compensation strategy table; And / or, a method for obtaining a load shedding threshold value set M for capacitor groups requiring additional shedding includes: based on power grid electromechanical simulation data, selecting a typical minimum startup mode for conventional units, simulating and analyzing the section short-circuit fault disconnection emergency control, after shedding different amounts of load according to priority, the voltage at the isolated grid system site recovers to k1 and k2 respectively, and the duration is greater than t3, the load shedding amounts are recorded as Pmk1 and Pmk2, and a capacitor shedding threshold value set M{Pmk1, Pmk2} is formed.

7. The emergency control method according to claim 1, characterized in that: During one emergency control cycle, the voltage information of key sites in the isolated grid system is monitored in real time. Based on the voltage information, the load shedding threshold value set M of the capacitor bank to be cut, the sites of the capacitor bank to be cut, and the corresponding cut capacitor capacity set C, it is determined whether the steady-state voltage of the key site of the isolated grid system is too high and the amount of load cut is greater than the capacitor cutting threshold value. If so, the corresponding capacitor bank is cut according to the preset capacitor cutting strategy table, including: Real-time monitoring of voltage information at key sites within the isolated grid system; In response to the critical site voltage U>k1 or U>k2, if either condition is met, the time is recorded as t2, t2-t1<5s, where t1 is the emergency control start time; compare whether the removed load amount Pl is greater than the value in the capacitor threshold value set M{Pmk1,Pmk2}; In response to Pmk2>Pl>Pmk1, the first level of cut-off capacity C in the corresponding cut-off capacitor capacity set C is selected according to the site where the capacitor bank needs to be cut off. Bn1 Cut off the corresponding capacitor group; In response to Pl>Pmk2, the second level of cut-off capacity C in the corresponding cut-off capacitor capacity set C is selected according to the site where the capacitor bank needs to be cut off. Bn2 Remove the corresponding capacitor bank.

8. The emergency control method according to claim 1, characterized in that: k1 is 1.07pu and k2 is 1.10pu.

9. An emergency control system driven by a protection signal trigger response, characterized in that: including processors and storage media; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1 to 8.

10. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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