A coordinated control method for multiple energy storage power stations to participate in alleviating line overload

Abstract

The present invention discloses a coordinated control method for multiple energy storage power stations to participate in alleviating line overload, which includes setting up multiple large-capacity energy storage power stations, an energy storage power station coordinated control system, and a real-time power monitoring device for the transmission line. The real-time detection device of the transmission line sends the detected current information of the line to the energy storage power station coordinated control system in real time. Each energy storage power station sends information such as charge and discharge status, remaining power, and overload capacity of the energy storage power station to the energy storage power station coordinated control system. When the monitored current of the transmission line is overloaded, each energy storage power station raises the control priority of the coordinated control system to the highest level. An emergency power regulation instruction is sent to each energy storage power station through a pre-established coordinated control strategy. After a delay of T seconds, each energy storage power station resumes its operating state before the fault, and the control priority of the coordinated control system is reduced to the original level. This can enable multiple energy storage power stations to exert their emergency power regulation capabilities, participate in eliminating line overload, and avoid further expansion of the fault.

Description

Technical Field

[0001] The invention belongs to the technical field of power system transmission, and particularly relates to a coordinated control method for multiple energy storage power stations to participate in alleviating line overload. Background Art

[0002] With the development and utilization of large-scale new energy such as wind power and photovoltaic power, large-scale cluster access is carried out in areas rich in new energy. In order to better promote the consumption of new energy and reduce the occurrence of wind and light abandonment, a certain proportion of electrochemical energy storage power stations will also be configured at new energy collection stations. When new energy is in large generation, there is a problem of line overload on key transmission channels. If a line tripping accident occurs at this moment, it may lead to line overload. Without taking measures, it will lead to the expansion of the accident. For such overload problems, traditional control measures usually adopt the means of stabilizing and cutting off some units in the sending-end power grid to eliminate overload. After the electrochemical energy storage is connected to the power grid, as the energy storage capacity gradually increases and the number of energy storage power stations increases, the energy storage has the ability of rapid charge and discharge conversion, which can switch the charge and discharge mode in dozens of milliseconds. At the same time, it also has a certain overload capacity in an emergency state, that is, it can switch from the normal charging mode to the overload large-current charging mode and from the normal discharge mode to the overload large-current discharge mode. Therefore, the electrochemical energy storage power station can be used as a good means to eliminate the line overload problem after a fault. When a large number of energy storage power stations are comprehensively utilized, it can be used as a new preventive measure before the traditional unit cutting means to reduce the occurrence of overload problems after a fault, promote the consumption of new energy, and reduce the phenomenon of restricting the output of new energy when wind and light are in large generation.

[0003] However, the electrochemical energy storage power station may operate in different states at each time period. How to judge the power that each energy storage power station can quickly adjust, whether the energy storage power station should charge or discharge after a fault occurs according to its access position, and which energy storage power stations need to be put into operation for the best effect for different overload degrees. No relevant research has been carried out on such problems. Summary of the Invention

[0004] The technical problem to be solved by the embodiment of the invention is to provide a coordinated control method for multiple energy storage power stations to participate in alleviating line overload. The overload degree is judged by monitoring the current of the transmission line. The operation state and remaining power information of each energy storage power station are collected in real time to judge the maximum adjustable power of each energy storage power station. The influence degree of the energy storage power station adjusting the unit active power on the reduction of the active power of the monitored line is judged according to the access position of each energy storage power station. Finally, according to the overload degree of the line, the specific stations of the energy storage power stations that need to be put into emergency control and the power that needs to be adjusted are judged, so as to achieve the purpose of quickly eliminating line overload.

[0005] To solve the above technical problems, the present invention provides a coordinated control method for multiple energy storage power stations to participate in alleviating line overload, characterized in that the control method includes:

[0006] A coordinated control method for multiple energy storage power stations to participate in alleviating line overload, characterized in that the control method includes: a plurality of large-capacity energy storage power stations, an energy storage power station coordinated control system, and a transmission line power real-time monitoring device. The transmission line real-time detection device sends the detected current information of the line to the energy storage power station coordinated control system in real time. Each energy storage power station sends information such as charge and discharge status, remaining power, and overload capacity of the energy storage power station to the energy storage power station coordinated control system. When the monitored transmission line current is overloaded, each energy storage power station raises the control priority of the coordinated control system to the highest level. An emergency power adjustment command is sent to each energy storage power station through a pre-established coordinated control strategy. After a delay of T seconds, each energy storage power station resumes its operating state before the fault, and the control priority of the coordinated control system is reduced to the original level.

[0007] Further, in the coordinated control method for multiple energy storage power stations to participate in alleviating line overload, the plurality of large-capacity energy storage power stations refer to electrochemical energy storage power stations.

[0008] Further, the coordinated control method for multiple energy storage power stations to participate in alleviating line overload is characterized in that the pre-established coordinated control strategy includes the following steps:

[0009] S3.1 The transmission line power real-time monitoring device sends the line current to the main station of the coordinated control system;

[0010] S3.2 Each energy storage power station sends information such as charge and discharge status, remaining power SOC, and short-term overload capacity K of the energy storage power station to the main coordinated control station;

[0011] S3.3 According to the location of each energy storage power station connected to the power grid, it is judged whether the power of each energy storage power station can be quickly adjusted to reduce the line overload current through the following four adjustment methods. The power quick adjustment switches among the following six states: switching from the charging state to charging with k times the overload capacity, switching from charging to discharging with k times the overload capacity, switching from the discharging state to discharging with k times the overload capacity, switching from discharging to charging with k times the overload capacity, switching from hot standby to the charging or discharging state.

[0012] S3.4 The main coordinated control station judges whether the energy storage power station can perform power quick adjustment according to the sent information. If it cannot be adjusted, the original operating state of the energy storage power station is maintained. If it can, the power quick adjustment of the energy storage power station is selected. The quickly adjustable powers of N energy storage power stations can be obtained as ΔP 1 、ΔP 2 ……ΔP N .

[0013] S3.5 According to the effect of the decrease in the unit active power changed by the energy storage power station on reducing the line power, the discharge power of the energy storage power station is represented as positive, and the charging power is represented as negative. That is, the effect of the magnitude of the unit discharge active power on reducing the line power or the effect of the increase in the unit charging power on reducing the line power is represented by the influence factor k. That is, the influence factors of the power quickly adjusted by N energy storage power stations on reducing the line power are k 1 、k 2 ……k N 。

[0014] S3.6 The coordinated control system calculates the power adjusted by each energy storage power station to reduce the power of the transmission line, which is k 1 *ΔP 1 、k 2 *ΔP 2 、……k N *ΔP N respectively, according to the power that the energy storage power station can adjust quickly in real time and the influence factor. Sort the products of the data from large to small to obtain the energy storage power station that has the greatest impact on changing the power of the transmission line.

[0015] S3.7 According to the monitored power overload state of the transmission line, it is calculated that the power that needs to be adjusted downward is ΔP j 。 According to the priority order in step S3.6, it is judged how many groups of energy storage are put into coordinated control to eliminate the line overload. When the sum of the powers k i *ΔP i of the input energy storage power stations is greater than or equal to ΔP j it is okay.

[0016] S3.8 After the energy storage power station is put into operation, it will gradually withdraw after a delay T, and the delay T is related to the designed overload capacity of the energy storage power station and the heat dissipation system.

[0017] Advantages of the present invention:

[0018] 1. During the line overload period, the present invention can quickly reduce the overload degree of the transmission line by switching the charge and discharge states of the energy storage power station, and strive for faster time for other regulation means.

[0019] 2. The present invention can determine the input mode and specific sites of the energy storage power station according to the overload degree of the line, and achieve precise control of the power flow. Description of the Drawings

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0021] Figure 1 This is a power grid structure diagram of an embodiment of the present invention including multiple energy storage power stations.

[0022] Figure 2 This is a schematic diagram of the steps of a coordinated control method for multiple energy storage power stations to participate in alleviating line overload in the present invention. Specific embodiments

[0023] The following descriptions of the embodiments refer to the drawings to exemplify specific embodiments in which the present invention can be implemented.

[0024] The embodiments of the present invention provide a coordinated control method for multiple energy storage power stations to participate in alleviating line overload. The method steps are as Figure 2 shown and are also described in the technical solution, so details are not repeated here. An example verification is carried out for the power grid structure diagram including multiple energy storage power stations as Figure 1 shown. The power grid structure in the example includes a new energy transmission system with large-scale photovoltaic, wind power, and energy storage, which is transmitted through a double-circuit line of transmission channel 1. Assume that the capacity of energy storage power station 1 is 100 MW / 200 MWh, the capacity of energy storage power station 2 is 120 MW / 240 MWh, the capacity of energy storage power station 3 is 120 MW / 240 MWh, and the capacity of energy storage power station 4 is 150 MW / 300 MWh. The power flow direction of transmission channel 1 is from bus A to bus B. The overload capacity of the four energy storage power stations is 1.5 times. According to the analysis of the power grid structure, it can be known that for every 1 MW reduction in the discharge power of energy storage power station 1, the power flow of transmission channel 1 can be reduced by 0.2 MW; for every 1 MW reduction in the discharge power of energy storage power station 2, the power flow of transmission channel 1 can be reduced by 0.25 MW; for every 1 MW reduction in the discharge power of energy storage power station 3, the power flow of transmission channel 1 can be reduced by 0.3 MW; for every 1 MW reduction in the discharge power of energy storage power station 4, the power flow of transmission channel 1 can be reduced by -0.3 MW. Thus, the correlation coefficients of energy storage power stations 1, 2, 3, and 4 are 0.2, 0.25, 0.30, and -0.3 respectively. The operating states of each energy storage power station and the correlation coefficients with the observed channel can be shown in the following table:

[0025]

[0026] As can be seen from the above table, after the transmission channel overload problem occurs, the power flow of the line can be effectively regulated through the power regulation of the energy storage power station. k*ΔP in the table represents the effect of the power flow regulation of each energy storage power station on the transmission channel after quickly switching the charge and discharge states and using the overload coefficient of the energy storage power station. The power regulation of Energy Storage Power Station 1 can reduce the power flow of Transmission Channel 1 by 38 MW, with the worst effect. The power regulation of Energy Storage Power Station 2 can reduce the power flow of Transmission Channel 1 by 75 MW, with the most obvious effect. The power regulation of Energy Storage Power Station 3 can reduce the power flow of Transmission Channel 1 by 72 MW. The power regulation of Energy Storage Power Station 4 can reduce the power flow of Transmission Channel 1 by 67.5 MW.

[0027] If the overload of Transmission Channel 1 is 140 MW, then the coordinated control master station only needs to put Energy Storage Power Station 2 and Energy Storage Power Station 1 into operation to eliminate the overload. If the overload of Transmission Channel 1 reaches 250 MW, then the coordinated control master station needs to involve all four energy storage power stations in the emergency control.

[0028] As can be seen from the table, during the line overload period, through the coordinated control of multiple energy storage power stations, the function of quickly reducing the line overload can be achieved. It can reserve processing time for subsequent regulation means and improve the safety of power grid operation.

[0029] The above-disclosed are only the preferred embodiments of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A coordinated control method for multiple energy storage power stations to participate in alleviating line overload, characterized in that, the control method includes: setting multiple large-capacity energy storage power stations, an energy storage power station coordinated control system, and a transmission line power real-time monitoring device; the transmission line power real-time detection device sends the detected line current information to the energy storage power station coordinated control system in real time, and each energy storage power station sends information including charge and discharge status, remaining power, and overload capacity of the energy storage power station to the energy storage power station coordinated control system. When the monitored transmission line current is overloaded, each energy storage power station raises the control priority of the coordinated control system to the highest level; an emergency power adjustment command is sent to each energy storage power station through a pre-developed coordinated control strategy. After a delay of T seconds, each energy storage power station resumes its operating state before the fault, and the control priority of the coordinated control system is reduced to the original level; the pre-developed coordinated control strategy includes the following steps: S3.1 The transmission line power real-time monitoring device sends the line current to the main station of the energy storage power station coordinated control system; S3.2 Each energy storage power station sends information including charge and discharge status, state of charge (SOC), and short-term overload capacity K of the energy storage power station to the main station of the energy storage power station coordinated control system; S3.3 According to the location of each energy storage power station connected to the power grid, it is judged whether the power of each energy storage power station can be quickly adjusted to reduce the line overload current through the following four adjustment methods. The power quick adjustment switches among the following six states: 1) switching from the charging state to charging with k times the overload capacity, 2) switching from charging to discharging with k times the overload capacity, 3) switching from the discharging state to discharging with k times the overload capacity, 4) switching from discharging to charging with k times the overload capacity; 5) switching from hot standby to the charging state; 6) switching from hot standby to the discharging state; S3.4 The master station of the energy storage power station coordination control system determines whether the energy storage power station can perform rapid power regulation based on the uploaded information. If it cannot perform regulation, the original operating state of the energy storage power station is maintained. If it can, rapid power regulation of the energy storage power station is selected; the powers of N energy storage power stations for rapid regulation are obtained as ΔP 1 , ΔP 2 ... ΔP N ; S3.5 According to the effect of the decrease in the unit active power changed by the energy storage power station on reducing the line power, the discharge power of the energy storage power station is expressed as positive and the charging power is expressed as negative, that is, the effect of the magnitude of the unit discharge active power on reducing the line power or the effect of the increase in the unit charging power on reducing the line power is represented by the influence factor k; that is, the influence factors of the power quickly adjusted by N energy storage power stations on reducing the line power are k 1 , k 2 ... k N ; S3.6 The energy storage power station coordination control system calculates, according to the power adjusted in real time and rapidly by the energy storage power station and the influence factors, the power of each energy storage power station's adjustment that reduces the transmission line power to be k 1 *ΔP 1 、k 2 *ΔP 2 ……k N *ΔP N ; Sort the product of the data from largest to smallest to obtain the energy storage power station that has the greatest change in the transmission line power; S3.7 Calculate the power ΔP that needs to be adjusted downward based on the monitored power overload status of the transmission line. j ; Determine how many energy storage units are to be involved in coordinated control according to the priority order in step S3.6 to eliminate line overload. When the sum of the power k i * ΔP i is greater than or equal to ΔP j it is sufficient. S3.8 After the energy storage power station is put into operation, after a delay of T, each energy storage power station resumes its operating state before the fault, and the control priority of the coordinated control system is reduced to the original level.

2. A coordinated control method for multiple energy storage power stations to participate in alleviating line overload according to claim 1, characterized in that the multiple large-capacity energy storage power stations refer to electrochemical energy storage power stations.

3. A coordinated control method for multiple energy storage power stations to participate in alleviating line overload according to claim 1, characterized in that characterized in that the delay T is related to the overload capacity and heat dissipation system designed for the energy storage power station.

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