A method and system for controlling voltage at a grid connection point of an AC weak power grid

Abstract

The present application provides a method and system for controlling the grid connection point voltage of an AC weak power grid, which relates to the field of power control technology and is used to improve the efficiency and accuracy of grid connection point voltage control. The method includes: if the grid connection point voltage does not reach the preset voltage, the maximum active power value of the first power station is determined by the fitting formula of the active power of the first power station and the grid connection node voltage; the grid connection point voltage corresponding to the first booster station is calculated by the maximum active power value, reactive power of the first power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station; if the grid connection point voltage does not reach the preset voltage, the maximum active power value is input into the fitting formula of the reactive power of the first power station and the grid connection node voltage to recalculate the reactive power of the first power station; the active power and reactive power of the first power station are adjusted according to the recalculated reactive power and the maximum active power value of the first power station.

Description

Technical Field

[0001] The present application relates to the field of power control technology, and in particular to a method and system for controlling the grid connection point voltage of an alternating current weak power grid. Background Art

[0002] For multi-machine grid-connected systems in weak AC power grids, each inverter may resonate, two inverters may couple with each other, and the inverter and the grid may couple through grid impedance. These three situations exist simultaneously in multi-machine grid-connected systems under weak power grid conditions, resulting in decreased stability or even instability of the multi-machine grid-connected system. The grid-connected operation of weak AC power grid systems may cause reverse flow problems, resulting in increased voltage or overvoltage at the grid connection point of the weak AC power grid system.

[0003] AC weak grids usually need to be connected to the grid through power electronic interfaces - inverters, and low-voltage or medium-voltage distribution networks. The traditional AC weak grid system transmission and distribution network is designed as a one-way transmission and distribution system from the power generation unit to the load. The grid connection of the AC weak grid system may cause the problem of reverse flow, resulting in voltage increase or overvoltage at the connection point of the AC weak grid system.

[0004] The increase in grid connection point voltage not only affects the power supply quality of local loads, but also increases the loss of power transmission and distribution equipment such as lines and transformers, causing system overload. Therefore, it is necessary to control the grid connection point voltage. However, relying solely on the traditional manual adjustment of grid connection point voltage cannot completely and effectively solve the problem of grid connection point voltage increase. Summary of the invention

[0005] The embodiments of the present application provide a method and system for controlling the grid connection point voltage of an AC weak power grid, which are used to improve the efficiency and accuracy of the grid connection point voltage control.

[0006] An embodiment of the present invention provides a method for controlling a grid connection point voltage of an AC weak power grid, the method being applied to a grid connection point voltage control device in a grid connection point voltage control system of an AC weak power grid, the system comprising: a first power station, a first booster station, a high-voltage transmission line, a power grid, and a grid connection point voltage control device, the output end of the first power station being connected to the input end of the first booster station, the first booster station being used to boost the output electric energy of the first power station to a preset voltage, and transmitting the boosted output electric energy to the power grid through the high-voltage transmission line; the method comprising:

[0007] Acquire the active power and reactive power of the first power station; and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station;

[0008] Calculate the grid connection point voltage corresponding to the first booster station according to the active power and reactive power of the first power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station, wherein the grid connection point is the high-voltage side bus or node where the first booster station is located;

[0009] Determining whether the grid connection point voltage corresponding to the first booster station reaches the preset voltage;

[0010] If the grid connection point voltage does not reach the preset voltage, the maximum active power of the first power station is determined by a fitting formula of the active power of the first power station and the grid connection point voltage;

[0011] Recalculate the grid connection point voltage corresponding to the first booster station by using the maximum active power and reactive power of the first power station and the equivalent resistance and equivalent reactance of the high-voltage transmission line corresponding to the first booster station;

[0012] Determining whether the recalculated grid connection point voltage corresponding to the first boost station reaches the preset voltage;

[0013] Based on the determination of whether the grid connection point voltage corresponding to the recalculated first booster station reaches the preset voltage, the active power and / or reactive power of the first power station is adjusted so that the grid connection point voltage corresponding to the recalculated first booster station reaches the preset voltage.

[0014] In an optional embodiment provided by the present invention, the active power and / or reactive power of the first power station is adjusted based on the determination of whether the grid connection point voltage corresponding to the recalculated first booster station reaches the preset voltage, so that the recalculated grid connection point voltage corresponding to the first booster station reaches the preset voltage, including:

[0015] If the grid connection point voltage corresponding to the recalculated first booster station does not reach the preset voltage, the maximum active power value is input into the fitting formula of the reactive power of the first power station and the grid connection node voltage to recalculate the reactive power of the first power station; the active power and reactive power of the first power station are adjusted according to the recalculated reactive power and the maximum active power value of the first power station, so that the grid connection point voltage corresponding to the recalculated first booster station reaches the preset voltage;

[0016] If the recalculated grid connection point voltage corresponding to the first booster station reaches the preset voltage, the active power of the first power station is adjusted according to the maximum active power of the first power station so that the recalculated grid connection point voltage corresponding to the first booster station reaches the preset voltage.

[0017] In an optional embodiment provided by the present invention, the active power and reactive power of the first power station are adjusted according to the recalculated reactive power and active power maximum value of the first power station, so that before the grid connection point voltage corresponding to the recalculated first booster station reaches the preset voltage, the method further includes:

[0018] Recalculate the grid connection point voltage corresponding to the first booster station by using the maximum active power of the first power station, the recalculated reactive power of the first power station, and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line;

[0019] Determining whether the recalculated grid connection point voltage corresponding to the first boost station reaches the preset voltage;

[0020] If the recalculated grid connection point voltage corresponding to the first booster station does not reach the preset voltage, obtaining position information of each line node after the grid connection point in the system;

[0021] According to the position information of the line node, a second power station and a second booster station are added at the corresponding line node in the system, so that the grid connection point voltage corresponding to the added second booster station reaches the preset voltage, the output end of the second power station is connected to the input end of the second booster station, and the second booster station is used to boost the output electric energy of the second power station to the preset voltage.

[0022] In an optional embodiment provided by the present invention, adding a second power station and a second booster station at the corresponding line node in the system according to the position information of the line node, so that the grid connection point voltage corresponding to the added second booster station reaches the preset voltage, includes:

[0023] Calculating a voltage difference between the preset voltage and the grid connection point voltage corresponding to the first booster station;

[0024] By using the voltage difference, a second power station and a second booster station are added at the corresponding line node in the system, so that the grid connection point voltage corresponding to the added second booster station reaches the preset voltage.

[0025] In an optional embodiment provided by the present invention, the adding of a second power station and a second booster station at a corresponding line node in the system by using the voltage difference so that the grid connection point voltage corresponding to the added second booster station reaches the preset voltage includes:

[0026] Obtaining the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to each line node after the grid connection point in the system, wherein the high-voltage transmission line corresponding to the line node is the high-voltage transmission line between the current line node and the power grid;

[0027] Simulate adding a second power station and a second booster station before each line node in turn, and calculate the grid connection point voltage corresponding to the simulated added second booster station based on the active power and reactive power of the simulated added second power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the second booster station;

[0028] When the calculated grid connection point voltage corresponding to the second booster station reaches the preset voltage, the nodes of the second power station and the second booster station are added at the corresponding line nodes.

[0029] In an optional embodiment provided by the present invention, the adding of a second power station and a second booster station at a corresponding line node in the system by using the voltage difference so that the grid connection point voltage corresponding to the added second booster station reaches the preset voltage includes:

[0030] Obtaining the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to each line node after the grid connection point in the system, wherein the high-voltage transmission line corresponding to the line node is the high-voltage transmission line between the current line node and the power grid;

[0031] The equivalent resistance value, equivalent reactance value, voltage difference value and positional relationship of all line nodes corresponding to the high-voltage transmission line of each line node are used to form a characteristic vector matrix;

[0032] Inputting the characteristic vector matrix into a power station location prediction model to obtain a power station location prediction result, wherein the power station location prediction result includes a line node position of a second power station added to the system;

[0033] According to the power station location prediction result, a second power station and a second booster station are added at the corresponding line node in the system.

[0034] In an optional embodiment provided by the present invention, the equivalent resistance value, equivalent reactance value, voltage difference value and positional relationship of all line nodes corresponding to the high-voltage transmission line of each line node are used to form a characteristic vector matrix, including:

[0035] Determine the line node corresponding to each row in the feature vector matrix according to the positional relationship of all line nodes;

[0036] The eigenvector corresponding to each row in the eigenvector matrix is ​​determined by the line node corresponding to each row, and the eigenvector is used to represent the equivalent resistance value, the equivalent reactance value and the voltage difference value of the corresponding line node.

[0037] In an optional embodiment provided by the present invention, the method further includes:

[0038] Acquire sample data for training the power station location prediction model, wherein the sample data includes a sample feature vector matrix and a sample label;

[0039] The power station location prediction model is obtained by performing model training using the present feature vector matrix and sample labels.

[0040] In an optional embodiment provided by the present invention, the step of inputting the maximum active power value into a fitting formula of reactive power of the first power station and grid-connected node voltage to recalculate the reactive power of the first power station comprises:

[0041] Determine n preset reactive powers of different values;

[0042] According to the order of the preset reactive power from small to large, the i-th preset reactive power and the maximum active power are input into the fitting formula of the reactive power of the first power station and the grid-connected node voltage to calculate the target grid-connected point voltage, where the value of i ranges from 1 to n;

[0043] If the target grid connection point voltage corresponding to the currently calculated i-th preset reactive power reaches the preset voltage, the i-th preset reactive power is determined as the reactive power of the first power station.

[0044] The embodiment of the present invention provides a grid connection point voltage control system for an AC weak power grid, the system comprising: a first power station, a first booster station, a high-voltage transmission line, a power grid, and a grid connection point voltage control device, wherein the output end of the first power station is connected to the input end of the first booster station, the first booster station is used to boost the output electric energy of the first power station to a preset voltage, and transmit the boosted output electric energy to the power grid through the high-voltage transmission line; the grid connection point voltage control device comprises:

[0045] An acquisition module, used to acquire the active power and reactive power of the first power station; and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station;

[0046] A calculation module, used to calculate the grid connection point voltage corresponding to the first booster station according to the active power and reactive power of the first power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station, wherein the grid connection point is the high-voltage side bus or node where the first booster station is located;

[0047] A determination module, used to determine whether the grid connection point voltage corresponding to the first boost station reaches the preset voltage;

[0048] The determination module is further configured to determine the maximum active power of the first power station by using a fitting formula of the active power of the first power station and the grid connection point voltage if the grid connection point voltage does not reach the preset voltage;

[0049] The calculation module is further used to recalculate the grid connection point voltage corresponding to the first booster station through the maximum active power and reactive power of the first power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station;

[0050] The determination module is further used to determine whether the recalculated grid connection point voltage corresponding to the first boost station reaches the preset voltage;

[0051] The calculation module is further configured to input the maximum active power value into the fitting formula of the reactive power of the first power station and the grid-connected node voltage to recalculate the reactive power of the first power station if the recalculated grid-connected point voltage corresponding to the first booster station does not reach the preset voltage;

[0052] An adjustment module, configured to adjust the active power and reactive power of the first power station according to the recalculated reactive power and active power maximum value of the first power station, so that the grid connection point voltage corresponding to the recalculated first booster station reaches the preset voltage;

[0053] The adjustment module is also used to adjust the active power of the first power station according to the maximum active power of the first power station if the recalculated grid connection point voltage corresponding to the first booster station reaches the preset voltage, so that the recalculated grid connection point voltage corresponding to the first booster station reaches the preset voltage.

[0054] The present invention provides a method and system for controlling the grid connection point voltage of an AC weak power grid. First, the grid connection point voltage corresponding to the first booster station is calculated according to the active power and reactive power of the first power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station, and then it is determined whether the grid connection point voltage corresponding to the first booster station reaches a preset voltage; if the grid connection point voltage does not reach the preset voltage, the maximum active power value of the first power station is determined by a fitting formula of the active power of the first power station and the grid connection point voltage; the grid connection point voltage corresponding to the first booster station is recalculated according to the maximum active power and reactive power of the first power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station; it is determined whether the recalculated grid connection point voltage corresponding to the first booster station reaches the preset voltage; based on the determination of whether the recalculated grid connection point voltage corresponding to the first booster station reaches the preset voltage, the active power and / or reactive power of the first power station are adjusted so that the recalculated grid connection point voltage corresponding to the first booster station reaches the preset voltage. Compared with the prior art which relies on traditional manual adjustment of the grid connection point voltage, the present application adjusts the first power station based on the re-determined active power and reactive power when it is determined that the grid connection point voltage has not reached the preset voltage, so that the grid connection point voltage corresponding to the first booster station reaches the preset voltage. Therefore, the present application improves the efficiency and accuracy of the grid connection point voltage control. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 A structural diagram of a voltage control system for a connection point of an AC weak power grid provided in this application;

[0056] Figure 2 A flow chart of a method for controlling the voltage at the grid connection point of an AC weak power grid provided in this application;

[0057] Figure 3 A schematic diagram of the structure of a grid connection point voltage control device provided in this application. DETAILED DESCRIPTION

[0058] In order to better understand the above-mentioned technical scheme, the technical scheme of the embodiments of the present application is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present application and the specific features in the embodiments are detailed descriptions of the technical scheme of the embodiments of the present application, rather than limitations on the technical scheme of the present application. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments may be combined with each other.

[0059] See also Figure 1, a grid connection point voltage control system of an AC weak power grid provided in an embodiment of the present invention, the system includes: a first power station, a first booster station, a high-voltage transmission line, a power grid, and a grid connection point voltage control device, the output end of the first power station is connected to the input end of the first booster station, the first booster station is used to boost the output electric energy of the first power station to a preset voltage, and transmit the boosted output electric energy to the power grid through the high-voltage transmission line.

[0060] In this embodiment, the grid connection point voltage control device can be set at the first power station end, or can be independently set in the control system. Figure 1 In the control system shown, the grid connection point voltage control device is separately provided and connected to the first power station, the first booster station and the high-voltage transmission line respectively. Then, the active power and reactive power of the first power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station are obtained through communication, so as to calculate the grid connection point voltage of the first booster station according to the obtained data, and redetermine the active power and reactive power of the first power station according to two fitting formulas, thereby realizing the control of the grid connection point voltage.

[0061] See also Figure 2 , a method for controlling the voltage of a grid connection point of an AC weak power grid provided by an embodiment of the present invention, which is applied to Figure 1 A grid connection point voltage control device in a control system, the method comprising the following steps:

[0062] S201, obtaining the active power and reactive power of the first power station; and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station.

[0063] It should be noted that each power station in this embodiment is provided with a corresponding booster station, through which the output power of the corresponding power station is boosted to a preset voltage, so as to transmit the boosted power to the power grid through a high-voltage transmission line. For example, when a 10kv AC bus is connected, the power is boosted to 110kv through the booster station.

[0064] S202: Calculate the grid connection point voltage corresponding to the first booster station according to the active power and reactive power of the first power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station.

[0065] Among them, the grid connection point is the high-voltage side bus or node where the first booster station is located.

[0066] Specifically, in one embodiment provided, the grid connection point voltage corresponding to the first booster station can be calculated by the following formula:

[0067]

[0068] Among them, U poi is the grid connection point voltage corresponding to the first booster station, U is the preset voltage, R g is the equivalent resistance value of the high-voltage transmission line corresponding to the first booster station, X g is the equivalent reactance value of the high-voltage transmission line corresponding to the first booster station, P poi is the active power of the first power station, Q poi is the reactive power of the first power station, the + in ± represents that the operation results in a stable real number solution, and the - represents that the operation results in an unstable real number solution. The preset voltage is the voltage value required for stable operation of the power grid.

[0069] S203, determining whether the grid connection point voltage corresponding to the first boost station reaches the preset voltage.

[0070] S204: If the grid connection point voltage does not reach the preset voltage, determining the maximum active power of the first power station by using a fitting formula of the active power of the first power station and the grid connection point voltage.

[0071] Among them, the fitting formula of the active power of the first power station and the voltage of the connecting node is obtained by fitting based on a large amount of historical data or sample data, and the data relationship between the active power of the first power station and the voltage of the connecting node can be determined by the fitting formula. Specifically, this embodiment can derive the fitting formula based on the calculation formula of the grid connection point voltage, such as by selecting the preset voltage U and the total installed capacity S of the power station as the reference value, S is the active power P actually transmitted to the large power grid by the grid connection point of the power station poi and reactive power Q poi Joint decision.

[0072] In this embodiment, after obtaining the fitting formula of the active power of the first power station and the grid-connected node voltage, a fitting curve is drawn based on the fitting formula (i.e., the horizontal axis is the active power of the first power station, and the vertical axis is the relationship curve of the grid-connected node voltage), and then the stable operating range of the grid-connected node voltage is determined based on the fitting curve. The grid-connected node voltage is close to the lowest amplitude in the stable range, and its corresponding horizontal axis is the maximum active power of the first power station.

[0073] S205: Recalculate the grid connection point voltage corresponding to the first booster station by using the maximum active power and reactive power of the first power station and the equivalent resistance and equivalent reactance of the high-voltage transmission line corresponding to the first booster station.

[0074] It should be noted that the calculation method of the grid connection point voltage corresponding to the first booster station in this embodiment is the same as the calculation method of step S202, and this embodiment will not be repeated here.

[0075] S206, determining whether the recalculated grid connection point voltage corresponding to the first boost station reaches the preset voltage.

[0076] S207, based on the determination of whether the grid connection point voltage corresponding to the recalculated first booster station reaches the preset voltage, the active power and / or reactive power of the first power station is adjusted so that the grid connection point voltage corresponding to the recalculated first booster station reaches the preset voltage.

[0077] In an optional embodiment provided in the present application, based on the determination of whether the grid connection point voltage corresponding to the recalculated first booster station reaches the preset voltage, the active power and / or reactive power of the first power station is adjusted so that the grid connection point voltage corresponding to the recalculated first booster station reaches the preset voltage, including:

[0078] S2071: If the recalculated grid-connected point voltage corresponding to the first booster station does not reach the preset voltage, the maximum active power value is input into the fitting formula of the reactive power of the first power station and the grid-connected node voltage to recalculate the reactive power of the first power station.

[0079] Among them, the fitting formula of the reactive power of the first power station and the grid-connected node voltage is obtained by fitting based on a large amount of historical data or sample data, and the data relationship between the reactive power of the first power station and the grid-connected node voltage can be determined through the fitting formula. When the reactive power generated by the inverter in the first power station participates in the system operation, the voltage change at the grid-connected point is different.

[0080] In this embodiment, after the grid-connected node voltage is adjusted by the active power of the first power station, the adjusted grid-connected node voltage still does not reach the preset voltage, and at this time, the grid-connected node voltage needs to be adjusted according to the reactive power of the first power station. That is, the reactive power of the first power station is re-determined according to the fitting formula of the reactive power of the first power station and the grid-connected node voltage, thereby controlling and adjusting the grid-connected node voltage to meet the preset voltage of the grid-connected node voltage.

[0081] In an optional embodiment provided in the present application, the reactive power of the first power station is recalculated by inputting the maximum active power value into the fitting formula of the reactive power of the first power station and the grid-connected node voltage, including: determining n preset reactive powers of different values; inputting the i-th preset reactive power and the maximum active power value into the fitting formula of the reactive power of the first power station and the grid-connected node voltage in order of the preset reactive powers from small to large to calculate the target grid-connected point voltage, where i ranges from 1 to n; if the target grid-connected point voltage corresponding to the currently calculated i-th preset reactive power reaches the preset voltage, the i-th preset reactive power is determined as the reactive power of the first power station.

[0082] For example, four preset reactive powers are set as a<b<c<d. First, the preset reactive power a and the maximum active power are input into the fitting formula of the reactive power of the first power station and the grid-connected node voltage to calculate the target grid-connected point voltage. If the calculated target grid-connected point voltage does not reach the preset voltage, the preset reactive power b and the maximum active power are input into the fitting formula of the reactive power of the first power station and the grid-connected node voltage to calculate the target grid-connected point voltage. If the calculated target grid-connected point voltage reaches the preset voltage, the preset reactive power b is determined as the reactive power of the first power station, and there is no need to continue calculating the target grid-connected point voltages of c and d.

[0083] S2072: Adjust the active power and reactive power of the first power station according to the recalculated reactive power and active power maximum values ​​of the first power station, so that the grid connection point voltage corresponding to the recalculated first boost station reaches the preset voltage.

[0084] S2073: If the recalculated grid connection point voltage corresponding to the first booster station reaches the preset voltage, adjust the active power of the first power station according to the maximum active power of the first power station so that the recalculated grid connection point voltage corresponding to the first booster station reaches the preset voltage.

[0085] The embodiment of the present invention provides a method for controlling the grid connection point voltage of an AC weak power grid. First, the grid connection point voltage corresponding to the first booster station is calculated according to the active power and reactive power of the first power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station, and then it is determined whether the grid connection point voltage corresponding to the first booster station reaches a preset voltage; if the grid connection point voltage does not reach the preset voltage, the maximum active power of the first power station is determined by a fitting formula of the active power of the first power station and the grid connection point voltage; the grid connection point voltage corresponding to the first booster station is recalculated according to the maximum active power and reactive power of the first power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station; and the recalculated first booster voltage is determined. Whether the grid connection point voltage corresponding to the first booster station reaches the preset voltage; if the recalculated grid connection point voltage corresponding to the first booster station does not reach the preset voltage, the maximum active power value is input into the fitting formula of the reactive power of the first power station and the grid-connected node voltage to recalculate the reactive power of the first power station; according to the recalculated reactive power and the maximum active power value of the first power station, the active power and reactive power of the first power station are adjusted, so that the recalculated grid connection point voltage corresponding to the first booster station reaches the preset voltage; if the recalculated grid connection point voltage corresponding to the first booster station reaches the preset voltage, the active power of the first power station is adjusted according to the maximum active power of the first power station, so that the recalculated grid connection point voltage corresponding to the first booster station reaches the preset voltage. Compared with the prior art which relies on traditional manual adjustment of the grid connection point voltage, the present application, when determining that the grid connection point voltage has not reached the preset voltage, redetermines the active power and reactive power of the first power station according to two fitting formulas, and then adjusts the first power station based on the redetermined active power and reactive power, so that the grid connection point voltage corresponding to the first booster station reaches the preset voltage. Thus, the present application improves the efficiency and accuracy of the grid connection point voltage control.

[0086] In an optional embodiment provided by the present invention, the active power and reactive power of the first power station are adjusted according to the recalculated reactive power and active power maximum value of the first power station, so that before the grid connection point voltage corresponding to the recalculated first booster station reaches the preset voltage, the method further includes:

[0087] S301, recalculating the grid connection point voltage corresponding to the first booster station by using the maximum active power of the first power station, the recalculated reactive power of the first power station, and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line.

[0088] S302, determining whether the recalculated grid connection point voltage corresponding to the first boost station reaches the preset voltage.

[0089] S303: If the recalculated grid connection point voltage corresponding to the first boost station does not reach the preset voltage, obtain the position information of each line node after the grid connection point in the system.

[0090] It should be noted that, since the traditional distribution network is a single radial structure, its voltage drop is the largest at the end of the distribution line, resulting in a low voltage at the end of the distribution network. Assuming that two adjacent line nodes in the distribution network are selected, the voltage drop between the two line nodes is:

[0091]

[0092] Among them, VU poi is the voltage drop of the two vector line nodes, U is the preset voltage (i.e., distribution network voltage), R g is the equivalent resistance value of the high-voltage transmission line corresponding to the first booster station, X g is the equivalent reactance value of the high-voltage transmission line corresponding to the first booster station, P poi is the active power of the first power station, Q poi is the reactive power of the first power station. The voltage drop in the distribution network and P poi , Q poi Positive correlation, active power is matched based on load characteristics, and its value remains basically unchanged to a certain extent. Therefore, reducing the reactive power of the distribution network can effectively improve the power quality of the distribution network.

[0093] Based on this, if the length of the high-voltage transmission line is long, the voltage at the end of the high-voltage transmission line will gradually show a downward trend. Therefore, after determining that the grid connection point voltage corresponding to the recalculated first booster station does not reach the preset voltage, this embodiment also needs to obtain the position information of each line node after the grid connection point in the system, and then add a second power station and a second booster station to the corresponding line node based on the acquired position information, so that the grid connection point voltage corresponding to the added second booster station reaches the preset voltage. Among them, in this embodiment, multiple line nodes are set in the high-voltage transmission line according to the line length.

[0094] S304: According to the position information of the line node, a second power station and a second booster station are added at the corresponding line node in the system, so that the grid connection point voltage corresponding to the added second booster station reaches the preset voltage.

[0095] The output end of the second power station is connected to the input end of the second boost station, and the second boost station is used to boost the output electric energy of the second power station to a preset voltage.

[0096] Specifically, adding a second power station and a second booster station at the corresponding line node in the system according to the position information of the line node, so that the grid connection point voltage corresponding to the added second booster station reaches the preset voltage, includes:

[0097] S3041: Calculate the voltage difference between the preset voltage and the grid connection point voltage corresponding to the first booster station.

[0098] S3042: adding a second power station and a second booster station at the corresponding line node in the system according to the voltage difference, so that the grid connection point voltage corresponding to the added second booster station reaches the preset voltage.

[0099] In an optional embodiment provided in the present application, the adding of a second power station and a second booster station at a corresponding line node in the system by using the voltage difference so that the grid connection point voltage corresponding to the added second booster station reaches the preset voltage includes:

[0100] S30421, obtaining the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to each line node after the grid connection point in the system.

[0101] The high-voltage transmission line corresponding to the line node is the high-voltage transmission line between the current line node and the power grid.

[0102] S30422, simulate adding a second power station and a second booster station before each line node in turn, and calculate the grid connection point voltage corresponding to the simulated added second power station based on the active power, reactive power of the simulated added second power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the second booster station.

[0103] The calculation method of the grid connection point voltage corresponding to the second booster station in this implementation is the same as Figure 2 The calculation method of the corresponding steps is the same, and this embodiment will not be repeated here.

[0104] S30423, when the calculated grid connection point voltage corresponding to the second booster station reaches the preset voltage, adding nodes of the second power station and the second booster station at the corresponding line nodes.

[0105] In another optional embodiment provided in the present application, the adding of a second power station and a second booster station at the corresponding line node in the system by the voltage difference so that the grid connection point voltage corresponding to the added second booster station reaches the preset voltage includes:

[0106] 30421, obtaining the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to each line node after the grid connection point in the system.

[0107] The high-voltage transmission line corresponding to the line node is the high-voltage transmission line between the current line node and the power grid.

[0108] 30422, the equivalent resistance value, equivalent reactance value, voltage difference value and positional relationship of all line nodes corresponding to the high-voltage transmission line are combined into a characteristic vector matrix.

[0109] Specifically, the equivalent resistance value, equivalent reactance value, the voltage difference value and the positional relationship of all line nodes corresponding to the high-voltage transmission line of each line node are used to form a characteristic vector matrix, including: determining the line node corresponding to each row in the characteristic vector matrix according to the positional relationship of all line nodes; determining the characteristic vector corresponding to each row through the line nodes corresponding to each row in the characteristic vector matrix, and the characteristic vector is used to represent the equivalent resistance value, equivalent reactance value and the voltage difference value of the corresponding line node.

[0110] 30423, input the characteristic vector matrix into the power station location prediction model to obtain the power station location prediction result, and the power station location prediction result includes adding the line node position of the second power station in the system.

[0111] It should be noted that the training process of the power station location prediction model in this embodiment is: obtaining sample data for training the power station location prediction model, the sample data including a sample feature vector matrix and a sample label; performing model training through the feature vector matrix and the sample label to obtain the power station location prediction model. The method for determining the sample feature vector matrix is ​​the same as the method for determining the feature vector matrix in 30422.

[0112] 30424. According to the prediction result of the power station location, a second power station and a second booster station are added at the corresponding line node in the system.

[0113] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0114] In one embodiment, a grid connection point voltage control device is provided, and the grid connection point voltage control device corresponds to the grid connection point voltage control method of the AC weak power grid in the above embodiment. Figure 3 As shown, the functional modules of the grid-connected point voltage control device are described in detail as follows:

[0115] An acquisition module 31 is used to acquire the active power and reactive power of the first power station; and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station;

[0116] A calculation module 32, configured to calculate the grid connection point voltage corresponding to the first booster station according to the active power and reactive power of the first power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station, wherein the grid connection point is the high-voltage side bus or node where the first booster station is located;

[0117] A determination module 33 is used to determine whether the grid connection point voltage corresponding to the first boost station reaches the preset voltage;

[0118] The determination module 33 is further configured to determine the maximum active power of the first power station by using a fitting formula of the active power of the first power station and the grid connection point voltage if the grid connection point voltage does not reach the preset voltage;

[0119] The calculation module 32 is further used to recalculate the grid connection point voltage corresponding to the first booster station by using the maximum active power and reactive power of the first power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station;

[0120] The determination module 33 is further used to determine whether the recalculated grid connection point voltage corresponding to the first boost station reaches the preset voltage;

[0121] The adjustment module 34 is used to adjust the active power and / or reactive power of the first power station based on the determination of whether the grid connection point voltage corresponding to the recalculated first booster station reaches the preset voltage, so that the recalculated grid connection point voltage corresponding to the first booster station reaches the preset voltage.

[0122] In an optional embodiment provided by the present invention, the calculation module 32 is further used to input the maximum active power value into the fitting formula of the reactive power of the first power station and the grid-connected node voltage to recalculate the reactive power of the first power station if the grid-connected point voltage corresponding to the recalculated first booster station does not reach the preset voltage;

[0123] An adjustment module 34, configured to adjust the active power and reactive power of the first power station according to the recalculated maximum reactive power and active power of the first power station, so that the grid connection point voltage corresponding to the recalculated first boost station reaches the preset voltage;

[0124] The adjustment module 34 is also used to adjust the active power of the first power station according to the maximum active power of the first power station if the recalculated grid connection point voltage corresponding to the first booster station reaches the preset voltage, so that the recalculated grid connection point voltage corresponding to the first booster station reaches the preset voltage.

[0125] In an optional embodiment provided by the present invention, the grid connection point voltage control device further includes an adding module 35, which is used to:

[0126] Recalculate the grid connection point voltage corresponding to the first booster station by using the maximum active power of the first power station, the recalculated reactive power of the first power station, and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line;

[0127] Determining whether the recalculated grid connection point voltage corresponding to the first boost station reaches the preset voltage;

[0128] If the recalculated grid connection point voltage corresponding to the first booster station does not reach the preset voltage, obtaining position information of each line node after the grid connection point in the system;

[0129] According to the position information of the line node, a second power station and a second booster station are added at the corresponding line node in the system, so that the grid connection point voltage corresponding to the added second booster station reaches the preset voltage, the output end of the second power station is connected to the input end of the second booster station, and the second booster station is used to boost the output electric energy of the second power station to the preset voltage.

[0130] In an optional embodiment provided by the present invention, the adding module 35 is specifically used for:

[0131] Calculating a voltage difference between the preset voltage and the grid connection point voltage corresponding to the first booster station;

[0132] By using the voltage difference, a second power station and a second booster station are added at the corresponding line node in the system, so that the grid connection point voltage corresponding to the added second booster station reaches the preset voltage.

[0133] In an optional embodiment provided by the present invention, the adding module 35 is specifically used for:

[0134] Obtaining the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to each line node after the grid connection point in the system, wherein the high-voltage transmission line corresponding to the line node is the high-voltage transmission line between the current line node and the power grid;

[0135] Simulate adding a second power station and a second booster station before each line node in turn, and calculate the grid connection point voltage corresponding to the simulated added second booster station based on the active power and reactive power of the simulated added second power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the second booster station;

[0136] When the calculated grid connection point voltage corresponding to the second booster station reaches the preset voltage, the nodes of the second power station and the second booster station are added at the corresponding line nodes.

[0137] In an optional embodiment provided by the present invention, a module 35 is added, which is specifically used for:

[0138] Obtaining the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to each line node after the grid connection point in the system, wherein the high-voltage transmission line corresponding to the line node is the high-voltage transmission line between the current line node and the power grid;

[0139] The equivalent resistance value, equivalent reactance value, voltage difference value and positional relationship of all line nodes corresponding to the high-voltage transmission line of each line node are used to form a characteristic vector matrix;

[0140] Inputting the characteristic vector matrix into a power station location prediction model to obtain a power station location prediction result, wherein the power station location prediction result includes a line node position of a second power station added to the system;

[0141] According to the power station location prediction result, a second power station and a second booster station are added at the corresponding line node in the system.

[0142] In an optional embodiment provided by the present invention, a module 35 is added, which is specifically used for:

[0143] Determine the line node corresponding to each row in the feature vector matrix according to the positional relationship of all line nodes;

[0144] The eigenvector corresponding to each row in the eigenvector matrix is ​​determined by the line node corresponding to each row, and the eigenvector is used to represent the equivalent resistance value, the equivalent reactance value and the voltage difference value of the corresponding line node.

[0145] In an optional embodiment provided by the present invention, sample data for training the power station location prediction model is obtained, and the sample data includes a sample feature vector matrix and sample labels; model training is performed using the feature vector matrix and sample labels to obtain the power station location prediction model.

[0146] In an optional embodiment provided by the present invention, the calculation module 32 is specifically used for:

[0147] Determine n preset reactive powers of different values;

[0148] According to the order of the preset reactive power from small to large, the i-th preset reactive power and the maximum active power are input into the fitting formula of the reactive power of the first power station and the grid-connected node voltage to calculate the target grid-connected point voltage, where the value of i ranges from 1 to n;

[0149] If the target grid connection point voltage corresponding to the currently calculated i-th preset reactive power reaches the preset voltage, the i-th preset reactive power is determined as the reactive power of the first power station.

[0150] For the specific definition of the grid connection point voltage control device, please refer to the definition of the grid connection point voltage control method for the AC weak power grid mentioned above, which will not be repeated here. Each module in the above device can be implemented in whole or in part by software, hardware and a combination thereof. Each of the above modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to each of the above modules.

[0151] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0152] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. A method for controlling grid-connected node voltage of an AC weak power grid, characterized in that: The method is applied to a grid-connected node voltage control device in a grid-connected node voltage control system of an AC weak power grid. The system comprises: a first power station, a first booster station, a high-voltage transmission line, a power grid, and a grid-connected node voltage control device. The output end of the first power station is connected to the input end of the first booster station. The first booster station is used to boost the output electric energy of the first power station to a preset voltage, and transmit the boosted output electric energy to the power grid through the high-voltage transmission line. The method comprises: Acquire the active power and reactive power of the first power station; and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station; Calculate the grid-connected node voltage corresponding to the first booster station according to the active power and reactive power of the first power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station, wherein the grid-connected node is the high-voltage side bus or node where the first booster station is located; Determining whether the grid-connected node voltage corresponding to the first boost station reaches the preset voltage; If the grid-connected node voltage does not reach the preset voltage, determining the maximum active power of the first power station by a fitting formula of the active power of the first power station and the grid-connected node voltage; Recalculate the grid-connected node voltage corresponding to the first booster station by using the maximum active power and reactive power of the first power station and the equivalent resistance and equivalent reactance of the high-voltage transmission line corresponding to the first booster station; Determining whether the recalculated grid-connected node voltage corresponding to the first boost station reaches the preset voltage; Based on the determination of whether the recalculated grid-connected node voltage corresponding to the first boost station reaches the preset voltage, adjusting the active power and / or reactive power of the first power station so that the recalculated grid-connected node voltage corresponding to the first boost station reaches the preset voltage; The step of adjusting the active power and / or reactive power of the first power station based on the determination of whether the recalculated grid-connected node voltage corresponding to the first booster station reaches the preset voltage so that the recalculated grid-connected node voltage corresponding to the first booster station reaches the preset voltage comprises: If the recalculated grid-connected node voltage corresponding to the first booster station does not reach the preset voltage, the maximum active power value is input into the fitting formula of the reactive power of the first power station and the grid-connected node voltage to recalculate the reactive power of the first power station; adjusting the active power and reactive power of the first power station according to the recalculated maximum values ​​of the reactive power and active power of the first power station, so that the grid-connected node voltage corresponding to the recalculated first boost station reaches the preset voltage; If the recalculated grid-connected node voltage corresponding to the first boost station reaches the preset voltage, adjusting the active power of the first power station according to the maximum active power of the first power station so that the recalculated grid-connected node voltage corresponding to the first boost station reaches the preset voltage; The method further comprises: adjusting the active power and reactive power of the first power station according to the recalculated maximum reactive power and active power of the first power station so that before the grid-connected node voltage corresponding to the recalculated first boost station reaches the preset voltage, the method further comprises: Recalculate the grid-connected node voltage corresponding to the first booster station by using the maximum active power of the first power station, the recalculated reactive power of the first power station, and the equivalent resistance value and the equivalent reactance value of the high-voltage transmission line; Determining whether the recalculated grid-connected node voltage corresponding to the first boost station reaches the preset voltage; If the recalculated grid-connected node voltage corresponding to the first booster station does not reach the preset voltage, obtaining position information of each line node after the grid-connected node in the system; According to the position information of the line node, a second power station and a second booster station are added at the corresponding line node in the system, so that the grid-connected node voltage corresponding to the added second booster station reaches the preset voltage, the output end of the second power station is connected to the input end of the second booster station, and the second booster station is used to boost the output electric energy of the second power station to the preset voltage.

2. The method according to claim 1, characterized in that The adding a second power station and a second booster station at the corresponding line node in the system according to the position information of the line node, so that the grid-connected node voltage corresponding to the added second booster station reaches the preset voltage, comprises: Calculating a voltage difference between the preset voltage and a grid-connected node voltage corresponding to the first boost station; By using the voltage difference, a second power station and a second boost station are added at the corresponding line node in the system, so that the grid-connected node voltage corresponding to the added second boost station reaches the preset voltage.

3. The method according to claim 2, characterized in that The method of adding a second power station and a second booster station at a corresponding line node in the system by using the voltage difference, so that the grid-connected node voltage corresponding to the added second booster station reaches the preset voltage, comprises: Obtaining the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to each line node after the grid-connected node in the system, wherein the high-voltage transmission line corresponding to the line node is the high-voltage transmission line between the current line node and the power grid; Simulate adding a second power station and a second booster station before each line node in turn, and calculate the grid-connected node voltage corresponding to the simulated added second power station based on the active power and reactive power of the simulated added second power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the second booster station; When the calculated grid-connected node voltage corresponding to the second booster station reaches the preset voltage, the nodes of the second power station and the second booster station are added at the corresponding line nodes.

4. The method according to claim 3, characterized in that The method of adding a second power station and a second booster station at a corresponding line node in the system by using the voltage difference, so that the grid-connected node voltage corresponding to the added second booster station reaches the preset voltage, comprises: Obtaining the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to each line node after the grid-connected node in the system, wherein the high-voltage transmission line corresponding to the line node is the high-voltage transmission line between the current line node and the power grid; The equivalent resistance value, equivalent reactance value, voltage difference value and positional relationship of all line nodes corresponding to the high-voltage transmission line of each line node are used to form a characteristic vector matrix; Inputting the characteristic vector matrix into a power station location prediction model to obtain a power station location prediction result, wherein the power station location prediction result includes a line node position of a second power station added to the system; According to the power station location prediction result, a second power station and a second booster station are added at the corresponding line node in the system.

5. The method according to claim 4, characterized in that The equivalent resistance value, equivalent reactance value, voltage difference value and positional relationship of all line nodes corresponding to the high-voltage transmission line of each line node are used to form a characteristic vector matrix, including: Determine the line node corresponding to each row in the feature vector matrix according to the positional relationship of all line nodes; The eigenvector corresponding to each row in the eigenvector matrix is ​​determined by the line node corresponding to each row, and the eigenvector is used to represent the equivalent resistance value, the equivalent reactance value and the voltage difference value of the corresponding line node.

6. The method according to claim 5, characterized in that The method further comprises: Acquire sample data for training the power station location prediction model, wherein the sample data includes a sample feature vector matrix and a sample label; The power station location prediction model is obtained by performing model training using the present feature vector matrix and sample labels.

7. The method according to claim 2, characterized in that The step of inputting the maximum active power value into a fitting formula of reactive power of the first power station and grid-connected node voltage to recalculate the reactive power of the first power station comprises: Determine n preset reactive powers of different values; According to the order of the preset reactive powers from small to large, the i-th preset reactive power and the maximum active power are input into the fitting formula of the reactive power of the first power station and the grid-connected node voltage to calculate the target grid-connected node voltage, where the value of i ranges from 1 to n; If the target grid-connected node voltage corresponding to the currently calculated i-th preset reactive power reaches the preset voltage, the i-th preset reactive power is determined as the reactive power of the first power station.

8. A grid-connected node voltage control system for an AC weak power grid, the system implementing the method according to claim 1, characterized in that: The system comprises: a first power station, a first booster station, a high-voltage transmission line, a power grid, and a grid-connected node voltage control device, wherein the output end of the first power station is connected to the input end of the first booster station, and the first booster station is used to boost the output electric energy of the first power station to a preset voltage, and transmit the boosted output electric energy to the power grid through the high-voltage transmission line; the grid-connected node voltage control device comprises: An acquisition module, used to acquire the active power and reactive power of the first power station; and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station; A calculation module, used to calculate the grid-connected node voltage corresponding to the first booster station according to the active power and reactive power of the first power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station, wherein the grid-connected node is the high-voltage side bus or node where the first booster station is located; A determination module, used to determine whether the grid-connected node voltage corresponding to the first boost station reaches the preset voltage; The determination module is further configured to determine the maximum active power of the first power station by using a fitting formula of the active power of the first power station and the grid-connected node voltage if the grid-connected node voltage does not reach the preset voltage; The calculation module is further used to recalculate the grid-connected node voltage corresponding to the first booster station by using the maximum active power and reactive power of the first power station and the equivalent resistance value and equivalent reactance value of the high-voltage transmission line corresponding to the first booster station; The determination module is further used to determine whether the recalculated grid-connected node voltage corresponding to the first boost station reaches the preset voltage; An adjustment module is used to adjust the active power and / or reactive power of the first power station based on the determination of whether the grid-connected node voltage corresponding to the recalculated first booster station reaches the preset voltage, so that the grid-connected node voltage corresponding to the recalculated first booster station reaches the preset voltage.

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