Implementation method and implementation system of power grid frequency stability emergency control system based on active power variation

Abstract

The invention discloses a power grid frequency stability emergency control system implementation method and implementation system based on active power variation, and the method comprises the steps: collecting the on-grid and off-grid active power variation of a substation collection device installation point, and transmitting the on-grid and off-grid active power variation to a main station, and collecting the controllable object state information of the installation point through an execution station, and transmitting the controllable object state information to the main station; the master station judges whether power flow transfer is caused by state change of the electromagnetic looped network; the master station sorts the received active power variation information of the upper network and the lower network according to absolute values; the master station calculates dP according to a formula and issues a control command to the execution stations according to controllable object properties, settable priorities and operation state information corresponding to the execution stations; the execution station immediately executes the control command after receiving the control command; aiming at the defects and deficiencies in the traditional power grid frequency stability emergency control technology, the frequency stability control measure needing to be taken is calculated according to the variable quantity of the active power and is sent to the controllable object to be executed, so that the frequency stability of the power grid is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to an implementation method and system of an emergency control system for power grid frequency stability, in particular to an implementation method and system of an emergency control system for power grid frequency stability based on active power variation. BACKGROUND

[0002] Traditional power system frequency stability emergency control systems are mainly based on device fault events to trigger directly and perform fast control according to power variation, such as calculating machine or load shedding according to the lost tie-line power when the tie-line is disconnected, and calculating corresponding control measures according to the lost DC power when the DC is blocked. However, with the access of large-scale new energy plants and energy storage devices, the complexity of the power grid has increased significantly, which makes the traditional stability control system appear to be inadequate when facing large-scale power outage or load mutation. On the one hand, a large number of stability control devices need to be deployed at key positions in the power grid, which not only increases the cost, but also puts high requirements on the communication network and the data processing capacity of the master station. On the other hand, when new energy is concentrated and connected to the grid and the load suddenly changes, the existing system is difficult to effectively control the frequency stability, and may only rely on lower-level control measures such as low-voltage and low-frequency load shedding devices to attempt to alleviate the instability of the power grid, but this is often not timely and effective in accident handling.

[0003] In recent years, more complex fault scenarios have appeared in new power systems, such as large-scale new energy simultaneously off-grid and multi-loop DC system failure, etc. The traditional frequency stability emergency control system has been difficult to adapt to the complex power grid environment, resulting in the system being difficult to maintain stable operation in the face of extreme faults. For example, the April 28, 2025 power outage in Spain and Portugal, due to a 15-gigawatt load drop, caused a sharp oscillation of the power grid frequency and voltage, and eventually had to be split. In the event of large-scale off-grid events and DC system failures, the existing system does not have the ability to handle such complex faults, and can only rely on lower-level control measures to attempt to restore grid stability, which not only affects the control effect, but also may bring additional risks. SUMMARY

[0004] The purpose of the present application is to provide an implementation method of an emergency control system for power grid frequency stability based on active power variation to effectively identify significant power fluctuations caused by changes in power supply or load, so as to quickly take corresponding control measures, help the power grid avoid or mitigate the risk of frequency instability, and ensure the frequency stability of the power grid. On the other hand, an implementation system of an emergency control system for power grid frequency stability based on active power variation is provided.

[0005] Technical solution: The implementation method of the emergency control system for power grid frequency stability according to the present application comprises the following steps:

[0006] S1, the upper and lower network active power variation of the substation collection device installation point is sent to the master station, and the controllable object state information of the execution station collection device installation point is sent to the master station; wherein the active power variation can be divided into four kinds of upper network power reduction, upper network power increase, lower network power reduction and lower network power increase;

[0007] S2, the master station judges whether it belongs to the power flow transfer caused by the electromagnetic loop network state change according to the number of sites with active power variation and the cumulative sum of power variation, if yes, the calculation is ended, otherwise the next step is entered;

[0008] S3, the master station sorts the received upper and lower network active power variation according to the absolute value;

[0009] S4, the master station excludes the active power variation absolute value smaller than the preset threshold;

[0010] S5, the master station performs absolute value accumulation on the reserved upper network power reduction and lower network power increase to obtain SumPG, and performs absolute value accumulation on the reserved upper network power increase and lower network power reduction to obtain SumPL;

[0011] S6, the master station calculates SumPG-SumPL=dP, when the absolute value of dP is less than the preset threshold, it returns, otherwise dP>0, the power of increasing power generation and cutting load is calculated according to the principle of equal or under cutting, dP<0, the power of increasing load and cutting generator is calculated according to the principle of equal or under cutting;

[0012] S7, the master station decomposes and issues the control power to the corresponding execution station according to the controllable object properties, the settable priority and the running state information of each execution station, and the execution station executes immediately after receiving the control command.

[0013] Preferably, the power grid frequency stability emergency control system is composed of an emergency control device, a communication device and a communication channel; the emergency control device is divided into a master station, a collection substation and an execution station.

[0014] Preferably, steps S3-S5 include a direct current transmission system, the direct current transmission system will cause transmission power reduction due to commutation failure or direct current system failure, if the commutation failure continues for a period of time and the direct current returns to normal operation, the active power transmission returns to normal; if the commutation failure exceeds a certain time and turns to direct current blocking, the active power transmission of the direct current transmission system has total or partial loss, the active power collection of the direct current transmission system is classified and marked for processing.

[0015] Preferably, the steps S3-S5 include new energy power generation equipment, the active power of which is changed when the wind speed and the illumination suddenly change, and the active power is changed when the abnormal grid frequency and voltage cause the anti-islanding protection to stop working, and the active power is changed according to the set characteristic curve when the grid fault causes the new energy to enter the high and low voltage ride-through process, and the change process is different from the voltage amplitude and the standard referred to when the new energy control logic is developed, and the active power collection quantity related to the new energy is classified and marked and processed.

[0016] Preferably, the steps S3-S5 classify and accumulate the active power through the main grid and multiple related branches, the grid frequency stability emergency control system supports the active power change caused by the simultaneous commutation failure, blocking or other types of faults of multiple DCs, and also supports the power analysis and control when other types of load devices simultaneously occur power mutation.

[0017] Preferably, when the main grid is split, the collection substation collects the device operating state and judges the main grid split state, the main station increases the frequency anti-misoperation measure when controlling and deciding, and the execution station increases the frequency anti-misoperation measure when implementing control.

[0018] Preferably, when cooperating with other second and third defense line control systems, the necessary action information is obtained from the second defense line control system and the grid frequency stability emergency control system is temporarily blocked; the necessary control information of the grid frequency stability emergency control system is sent to the second defense line control system for temporary blocking, and when the frequency exceeds a certain range, the third defense line control system is activated, and the grid frequency stability emergency control system is blocked.

[0019] The grid frequency stability emergency control system implementation system provided by the application comprises:

[0020] A data collection module is used for sending the active power change of the upper and lower grids of the collection substation installation point to the main station, and sending the controllable object state information of the execution station installation point to the main station, and the equipment for measuring the active power of the upper and lower grids includes AC lines, transformers, DC lines, back-to-back DCs and flexible power transmission equipment.

[0021] A state judgment module is used for accumulating the received active power change of the upper and lower grids, and judging whether it belongs to the power flow transfer caused by the electromagnetic looped network state change.

[0022] A control strategy calculation module is configured to sort the active power change amount according to absolute values, and exclude the active power change amount absolute values smaller than a preset threshold; and to obtain SumPG by accumulating the absolute values of the on-grid power reduction amount and the off-grid power increase amount, and to obtain SumPL by accumulating the absolute values of the on-grid power increase amount and the off-grid power reduction amount, and to calculate the difference SumPG-SumPL=dP.

[0023] An execution control module is configured to obtain the control power of the power generation load according to dP, and to decompose and issue the control power to the corresponding execution stations according to the controllable object properties, priority levels and operation state information of the execution stations to perform corresponding control operations.

[0024] Advantages: Compared with the prior art, the present application has the following significant advantages: 1. By real-time collection and analysis of the active power change amount of the on-grid and off-grid, the system can quickly identify the power imbalance in the power grid and immediately take corresponding frequency stability measures to effectively prevent severe fluctuations in the frequency and improve the overall frequency stability of the power grid; 2. By the state and priority of each device, the power control measures can be accurately executed, not only meeting the emergency needs under the condition of power frequency instability, but also differentiating responses to different types of changes to ensure that the control measures are more scientific and reasonable; 3. By timely detection and classification processing of the active power change, potential frequency instability can be accurately identified at an early stage, effectively shortening the response time and improving the timeliness and accuracy of the control measures; 4. By optimizing the power distribution between the generator set and the load, unnecessary power generation or shutdown can be reduced, repeated start-stop operations can be avoided, energy can be saved, operating costs can be reduced, and the utilization efficiency of power grid resources can be improved; 5. After the distribution of a large number of new energy and other types of power sources or loads in the power grid, the control system architecture does not need to be changed and the system does not need to be upgraded, reducing the distribution of devices and system upgrades compared to traditional stability control systems; 6. It has the ability to handle main power grid splitting, cooperation with the second and third line control systems, and other aspects to prevent frequency instability and enhance the anti-interference ability and self-healing ability of the power grid. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The present application is a method flowchart. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be further described below in conjunction with the drawings.

[0027] The power grid frequency stability emergency control system is composed of an emergency control device, communication equipment and a communication channel. According to different functions, the emergency control device can be divided into a master station, a collection substation and an execution station.

[0028] The master station is responsible for analyzing and processing the active power information and controllable object information collected by each collection sub-station and execution station, and when the analysis finds that there is a risk of frequency instability, the master station calculates and generates reasonable frequency stability control measures and sends them to the execution station.

[0029] The collection sub-station is responsible for collecting the active power, frequency and related equipment operating state of the installation point and sending them to the master station. The collection sub-station is deployed in the power substation with power in the upper and lower networks in the main power grid, and in the power substation involving electromagnetic loop network in the operation process.

[0030] The execution station is responsible for collecting the controllable object state and frequency information of the installation point and sending them to the master station, and is responsible for executing the control commands from the master station. The execution station is deployed at the controllable object, which includes but is not limited to conventional generator set, pumped storage unit, new energy unit, energy storage device, load, line or transformer as load, and direct current transmission system. The state information of the controllable object includes but is not limited to the start-stop state of the device, the current active power situation (including direction), and the adjustable active power situation. The state information of the energy storage as a special controllable device also includes the remaining power information (SOC).

[0031] The method of the power grid frequency stability emergency control system based on active power change amount can be realized based on a special stability control device or integrated as a part of the stability control device. The method specifically includes the following steps:

[0032] S1, the collection sub-station collects the active power change amount of the installation point and sends it to the master station, and the execution station collects the controllable object state information of the installation point and sends it to the master station. The active power change amount can be divided into "upper network power reduction", "upper network power increase", "lower network power reduction" and "lower network power increase" according to the characteristics of the data.

[0033] S2, the master station judges whether the change of the active power of the upper and lower networks is caused by the change of the electromagnetic loop network state according to the number of sites with active power change and the cumulative sum of the power change amount. If yes, the calculation is ended, otherwise the next step is entered.

[0034] S3, the master station sorts the received active power change amount according to the absolute value.

[0035] S4, the master station excludes the active power change amount with an absolute value less than the preset threshold Pmk.

[0036] S5, the master station adds the absolute values of each "upper network power reduction" and "lower network power increase" to obtain SumPG, and adds the absolute values of "upper network power increase" and "lower network power reduction" to obtain SumPL.

[0037] S6, the master station calculates SumPG-SumPL=dP, when the absolute value of dP is less than the settable threshold Pkmk, then return, otherwise dP>0, according to the principle of equivalent or under-cutting, the power of increasing power generation or cutting load is calculated; dP<0, according to the principle of equivalent or under-cutting, the power of increasing load or cutting generator is calculated.

[0038] Specifically, through the classification and cancellation processing of the active power of the relevant branches of the backbone power grid, the power grid frequency stability emergency control system based on the active power change amount can support a large number of new energy power supply devices including wind power, photovoltaic, and load devices such as multi-loop direct current, and power analysis and control when a large number of power supply devices and load devices simultaneously occur power mutation. The control power of power generation and load cutting calculated according to dP can be calculated according to the principle including but not limited to equivalent, under-cutting, or over-cutting. The calculation method can include but is not limited to direct processing according to dP, proportional or formula control according to dP, and formula considering frequency characteristics. Different calculation methods and formulas can be used for different types of power changes.

[0039] S7, the master station decomposes and issues the control power to the corresponding execution station according to the nature of the controllable object corresponding to each execution station, the settable priority level and the running state information. The execution station executes immediately after receiving the control command.

[0040] The splitting of the backbone power grid will affect the control effect of the power grid frequency stability emergency control system. The measures that can be taken include but are not limited to: collecting the running state of the substation collection equipment and judging the splitting state of the backbone power grid; the master station increases the frequency anti-misoperation measure when making control decisions; the execution station increases the frequency anti-misoperation measure when implementing control.

[0041] The cooperation with other second and third line of defense control systems needs to be considered to prevent mutual interference with other control systems and affect the control implementation effect. The measures that can be taken include but are not limited to: obtaining necessary action information from the second line of defense control system and temporarily locking the system; sending necessary control information of the system to the second line of defense control system for temporary locking; locking the system when the frequency exceeds a certain range and the third line of defense control system may act.

[0042] The direct current transmission system can be included in steps S3-S5. The direct current transmission system may reduce the transmission power due to commutation failure or direct current system failure. If it is commutation failure, the direct current may resume normal operation after a period of time, and the active power transmission also resumes normal operation. It may also be that the commutation failure exceeds a certain time and turns into direct current lockout, and the active power transmission of the direct current transmission system is lost in whole or in part. Therefore, the active power collection quantity related to the direct current transmission system should be classified and marked and specially processed. The processing means include but are not limited to that the active power is still unable to recover after a settable appropriate delay, and then the analysis and control are performed.

[0043] The new energy power generation equipment can be included in steps S3-S5. The active power of the new energy power generation equipment can change when the wind speed or the illumination suddenly changes, can be stopped due to the anti-islanding protection action caused by the abnormal grid frequency or voltage, and can change according to the set characteristic curve when the grid fault occurs, and the change process is different from the voltage amplitude and the standard referred to when the new energy control logic is developed. Therefore, the active power collection quantity related to the new energy should be classified and marked and specially processed, and the processing means include but are not limited to analyzing and controlling according to the recovery of the active power after the set delay.

[0044] In steps S3-S5, through the active power classification and accumulation processing of the multiple related branches of the main grid, the grid frequency stability emergency control system based on the active power change quantity can support the active power change caused by the simultaneous commutation failure, blocking or other types of faults of multiple HVDCs, and can also support the power analysis and control when other types of load devices simultaneously occur power mutation. Through the active power classification and accumulation processing of the related branches of the main grid, the grid frequency stability emergency control system based on the active power change quantity can support the power analysis and control when a large number of new energy power sources such as wind power and photovoltaic power simultaneously occur power mutation.

[0045] The grid frequency stability emergency control system based on the active power change quantity includes:

[0046] A data acquisition module is configured to send the active power change quantity of the upper and lower grids at the installation point of the substation acquisition device to the main station, and send the state information of the controllable object at the installation point of the execution station acquisition device to the main station. The devices for measuring the active power of the upper and lower grids include but are not limited to AC lines, transformers, DC lines, back-to-back DC, and flexible power transmission devices.

[0047] A state judgment module is configured to accumulate the received active power change quantity of the upper and lower grids, and judge whether it is caused by the electromagnetic looped network state change.

[0048] A control strategy calculation module is configured to sort the active power change quantity according to the absolute value, and exclude the active power change quantity absolute value smaller than the preset threshold. The absolute values of the power reduction amount and the power increase amount are accumulated to obtain SumPG, and the absolute values of the power increase amount and the power reduction amount are accumulated to obtain SumPL. The difference SumPG-SumPL=dP is calculated.

[0049] The execution control module is used for obtaining the control power of the power generation load according to dP, and decomposing and issuing the control power to the corresponding execution station to execute the corresponding control operation according to the controllable object property, priority level and operation state information corresponding to each execution station.

[0050] The design idea of the application is described below based on three fault scenarios.

[0051] Fault scenario 1: when the power grid is normally and stably operated, a fault occurs suddenly and part of the power supply is lost, for example, a conventional power plant or unit, a new energy station, a power transmission tie line, the branch power of the main power grid connected by the power supply changes instantaneously, and the difference is approximately equal to the power generation power of the lost power supply, at this time, other power generators in the power grid will provide a certain additional power generation output, so the active power flowing in and out at each place of the main power grid will change and reach a new balance instantaneously. Since power generation and load are not usually arranged in a centralized manner, the branch power change value of the fault power plant connected to the main power grid is the largest, and the positive and negative of the change value can reflect that the fault nature of the current power grid is the loss of power supply.

[0052] Fault scenario 2: when a certain sending-end power grid is normally and stably operated, the commutation failure of the rectifier side DC converter station is locked, the branch power of the main power grid connected by the fault converter station changes instantaneously, and the change value is approximately equal to the power transmission power of the lost DC, at this time, other power generators in the power grid will instantaneously reduce the power generation output, and the active power flowing in and out at each place of the main power grid will change and reach a new balance instantaneously. Since power generation and load are not usually arranged in a centralized manner, the branch power change value of the fault converter station connected to the main power grid is the largest, and the positive and negative of the change value can reflect that the fault nature of the current power grid is the loss of load.

[0053] Fault scenario 3: when the power grid has an electromagnetic ring network, the high-voltage side line of the electromagnetic ring network is suddenly tripped during normal and stable operation, and the power flow instantaneously flows to the low-voltage side line, and the branch power of the two or more branches of the main power grid connected by the electromagnetic ring network changes, since only power flow transfer occurs, considering the influence of loss, the sum of the up and down grid power change values at each place of the main power grid is close to 0.

[0054] Therefore, the design idea of the application is to arrange a certain number of devices in the main power grid, analyze the change value information of the up and down grid active power at each place of the main power grid in real time, when a sudden change in active power is found, first exclude the power flow transfer fault caused by the state change of the electromagnetic ring network, then calculate the frequency stability control measures to be taken according to the change value of the active power, and send the control information to the controllable object for execution.

Claims

1. A method for implementing an emergency control system for grid frequency stability based on changes in active power, characterized in that, Includes the following steps: S1. The active power changes of the upper and lower networks at the acquisition device installation point of the acquisition substation are sent to the main station, and the status information of the controllable objects at the acquisition device installation point of the execution station are sent to the main station. Among them, the change in active power can be divided into four types: decrease in power connected to the grid, increase in power connected to the grid, decrease in power disconnected from the grid, and increase in power disconnected from the grid. S2. The main station determines whether the power flow transfer is caused by the change in the state of the electromagnetic ring network by summing the number of stations with changes in active power in the upper and lower networks and the amount of power change. If it is, the calculation ends; otherwise, proceed to the next step. S3. The master station sorts the received changes in active power between the upstream and downstream networks according to their absolute values. S4. The main station excludes the absolute value of active power changes that are smaller than the preset threshold value. S5. The main station will sum the absolute values ​​of the retained reduction in internet power and the increase in offline power to obtain SumPG, and sum the absolute values ​​of the retained increase in internet power and the reduction in offline power to obtain SumPL. S6. The main station calculates SumPG-SumPL=dP. If the absolute value of dP is less than the preset threshold, it returns. Otherwise, if dP>0, it calculates the power to increase generation and load shedding according to the principle of equal or under-shearing. If dP<0, it calculates the power to increase load and shedding generator according to the principle of equal or under-shearing. S7. The master station decomposes the control power and sends it to the corresponding execution station based on the nature of the controllable object, the settable priority level, and the operating status information of each execution station. The execution station executes the control command immediately upon receiving it.

2. The method for implementing the emergency control system for power grid frequency stability according to claim 1, characterized in that, The power grid frequency stability emergency control system consists of an emergency control device, communication equipment, and a communication channel; the emergency control device is divided into a master station, a data acquisition substation, and an execution station.

3. The method for implementing the emergency control system for power grid frequency stability according to claim 1, characterized in that, Steps S3-S5 include the DC transmission system, which may experience a reduction in transmission power due to commutation failure or DC system fault. If the DC system resumes normal operation after a period of time following the commutation failure, the transmitted active power will return to normal. If the DC system is blocked after a certain period of time following the commutation failure, the active power transmitted by the DC transmission system will be lost in whole or in part. The active power data collected by the DC transmission system will be classified, marked and processed.

4. The method for implementing the emergency control system for power grid frequency stability according to claim 1, characterized in that, Steps S3-S5 include new energy power generation equipment. The active power output of the new energy power generation equipment will change accordingly when wind speed and illuminance suddenly change. It will also shut down due to abnormal grid frequency, voltage and other factors that trigger anti-islanding protection. When a grid fault occurs, the new energy will enter the high- and low-voltage ride-through process due to changes in the voltage amplitude at the grid connection point. Its active power output will change according to the set characteristic curve. The process of change is different from the voltage amplitude and the standard referenced when the new energy control logic is developed. The active power data related to the new energy are classified, marked and processed.

5. The method for implementing the emergency control system for power grid frequency stability according to claim 1, characterized in that, Steps S3-S5 classify and accumulate the active power through multiple related branches of the main power grid. The power grid frequency stability emergency control system supports active power changes caused by multiple DC circuits experiencing commutation failure, blocking, or other types of faults simultaneously. It also supports power analysis and control when other types of load equipment experience power mutations simultaneously.

6. The method for implementing the emergency control system for power grid frequency stability according to claim 1, characterized in that, When the main power grid is disconnected, the data acquisition substation collects the operating status of the equipment and determines the disconnection status of the main power grid. The master station adds frequency anti-misoperation measures when making control decisions, and the execution station adds frequency anti-misoperation measures when implementing control.

7. The method for implementing the emergency control system for power grid frequency stability according to claim 1, characterized in that, When cooperating with other second and third line-of-defense control systems, it obtains necessary action information from the second line-of-defense control system and temporarily locks the power grid frequency stability emergency control system; it sends necessary control information of the power grid frequency stability emergency control system to the second line-of-defense control system for temporary locking; when the frequency exceeds a certain range and the third line-of-defense control system operates, it locks the power grid frequency stability emergency control system.

8. A system for implementing an emergency control system for grid frequency stability based on changes in active power, characterized in that, include: The data acquisition module is used to collect the changes in active power between the upstream and downstream grids at the installation points of the substation acquisition devices and send them to the main station. It also sends the status information of controllable objects at the installation points of the execution station acquisition devices to the main station. The equipment used to measure the active power between the upstream and downstream grids includes AC lines, transformers, DC lines, back-to-back DC lines, and flexible transmission equipment. The status judgment module is used to accumulate the received changes in active power between the upper and lower networks and determine whether the power flow transfer is caused by changes in the electromagnetic ring network status. The control strategy calculation module is used to sort the changes in active power according to their absolute values ​​and exclude the absolute values ​​of the changes in active power that are smaller than a preset threshold. The absolute values ​​of the decrease in internet power and the increase in offline power are summed to obtain SumPG, and the absolute values ​​of the increase in internet power and the decrease in offline power are summed to obtain SumPL. The difference SumPG-SumPL=dP is calculated. The execution control module is used to obtain the control power of the power generation load based on dP, and decompose the control power according to the nature, priority level and operating status information of the controllable object corresponding to each execution station, and then send it to the corresponding execution station to perform the corresponding control operation.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the power grid frequency stability emergency control system implementation method as described in any one of claims 1 to 7.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the power grid frequency stability emergency control system implementation method as described in any one of claims 1 to 7.

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