Stable control method, device and system applicable to low-frequency AC power transmission system

Abstract

The present invention relates to the technical field of power system security and stability analysis, and discloses a stability control method, device and system applicable to a low-frequency AC power transmission system. When a tripping fault occurs in the receiving-end line of the low-frequency AC power transmission system, the present invention determines the corresponding power loss amount and the faulty line, selects a target control strategy according to the faulty line, and obtains the setting coefficient of the target control strategy; the setting coefficient includes a power frequency generator tripping coefficient and a power frequency generator tripping base value; calculates the corresponding stability control amount according to the power frequency system transmission frequency, the low-frequency AC system transmission frequency, the power loss amount and the setting coefficient; compares the magnitudes of the calculated stability control amount, the low-frequency power transmission and the maximum controllable amount, and executes corresponding security and stability control measures according to the obtained comparison result. The present invention can effectively solve the problem of security and stability control for the transmission of a low-frequency AC power transmission system, reduce the over-cut amount of stability control, and improve the stability control effect.

Description

Technical Field

[0001] The present invention relates to the technical field of power system security and stability analysis, and particularly to a stability control method, device and system applicable to a low-frequency AC power transmission system. Background Art

[0002] For medium- and long-distance offshore wind power, low-frequency AC power transmission, as a highly competitive offshore wind power transmission solution, improves the power transmission efficiency by reducing the power transmission frequency of the offshore AC system. The low-frequency AC power transmission technology converts the low-frequency alternating current generated by offshore wind power into industrial frequency power through frequency converters such as DRU-MMC or M3C and supplies it to the large power grid.

[0003] Compared with traditional flexible power transmission technology, the frequency converter cannot control the transmission power of the low-frequency AC network, and the transmission power of the low-frequency AC network is determined by the power generation power of the wind turbines. This limits the capacity of the power receiving channel when a fault occurs in the relevant lines of the receiving-end power grid. To ensure the safe operation of the low-frequency AC power transmission system, rapid stability control measures need to be taken at this time. However, at present, the low-frequency AC power transmission system is still in the exploration stage, and there is no good stability control method and system. In addition, due to the longer opening time of the circuit breaker of the low-frequency AC power transmission system than that of the traditional industrial frequency circuit breaker, the existing stability control effect is not ideal. Summary of the Invention

[0004] The present invention provides a stability control method, device and system applicable to a low-frequency AC power transmission system, and solves the technical problem of how to effectively realize the safe and stable control of the power transmitted by the low-frequency AC power transmission system.

[0005] The first aspect of the present invention provides a stability control method applicable to a low-frequency AC power transmission system, where the low-frequency AC power transmission system transmits power to the industrial frequency power grid through a frequency converter, and the method includes:

[0006] Obtain operation information; the operation information includes the power transmission frequency of the industrial frequency system, the power transmission frequency of the low-frequency AC system, the low-frequency transmission power, the maximum controllable amount, and the operation power of each low-frequency wind turbine control terminal;

[0007] When a trip fault occurs in the receiving-end line of the low-frequency AC power transmission system, determine the corresponding power loss amount and the fault line, select a target control strategy according to the fault line, and obtain the setting coefficient of the target control strategy; the setting coefficient includes the industrial frequency generator tripping coefficient and the industrial frequency generator tripping base value;

[0008] Calculate the corresponding stability control amount according to the power transmission frequency of the industrial frequency system, the power transmission frequency of the low-frequency AC system, the power loss amount, and the setting coefficient;

[0009] Compare the magnitudes of the calculated stable control quantity, the low-frequency power transmission power, and the maximum controllable quantity, and implement corresponding security and stability control measures according to the obtained comparison results;

[0010] Among them, the security and stability control measures include:

[0011] When the stable control quantity is greater than the low-frequency power transmission power, lock the frequency converter through the frequency converter control system and issue an alarm for insufficient control quantity;

[0012] When the stable control quantity is not greater than the low-frequency power transmission power and is greater than the maximum controllable quantity, lock the frequency converter through the frequency converter control system;

[0013] When the stable control quantity is not greater than the maximum controllable quantity, determine the control terminals that need to be executed from each low-frequency wind turbine control terminal according to the stable control quantity, and send control commands to the control terminals that need to be executed so that the terminals that need to be executed cut off the corresponding wind turbines.

[0014] According to an implementable manner of the first aspect of the present invention, the selecting the target control strategy according to the faulty line includes:

[0015] Match the corresponding control strategy from the preset strategy library as the target control strategy according to the faulty line; the preset strategy library stores a list of the corresponding relationships between faulty lines and control strategies.

[0016] According to an implementable manner of the first aspect of the present invention, the calculating the corresponding stable control quantity according to the power frequency system transmission frequency, the low-frequency AC system transmission frequency, the power loss quantity, and the fixed value setting coefficient includes:

[0017] Calculate the frequency conversion coefficient of the stable control generator tripping coefficient under low-frequency power transmission and the frequency conversion coefficient of the stable control generator tripping base value under low-frequency conditions according to the power frequency system transmission frequency and the low-frequency AC system transmission frequency;

[0018] Calculate the corresponding stable control quantity according to the following formula:

[0019] Dp = K K × Kset × (P - Pset × P K )

[0020] In the formula, Dp represents the stable control quantity, P is the power loss quantity, Kset is the power frequency generator tripping coefficient, Pset is the power frequency generator tripping base value, K K is the frequency conversion coefficient of the stable control generator tripping coefficient under low-frequency power transmission, and P K is the frequency conversion coefficient of the stable control generator tripping base value under low-frequency conditions.

[0021] According to an implementable manner of the first aspect of the present invention, the frequency conversion coefficient for calculating the stable control generator tripping coefficient under low-frequency power transmission and the frequency conversion coefficient for the stable control generator tripping base value under low-frequency conditions include:

[0022] Calculate the frequency conversion coefficient for the stable control generator tripping coefficient under low-frequency power transmission and the frequency conversion coefficient for the stable control generator tripping base value under low-frequency conditions according to the following formula:

[0023]

[0024] In the formula, f 0 is the power frequency system power transmission frequency, f 1 is the low-frequency AC system power transmission frequency, K is a preset adjustment coefficient, α is a preset first power value, and β is a preset second power value.

[0025] According to an implementable manner of the first aspect of the present invention, the frequency conversion coefficient for calculating the stable control generator tripping coefficient under low-frequency power transmission and the frequency conversion coefficient for the stable control generator tripping base value under low-frequency conditions further include:

[0026] Set K = 1, α = 1, β = 1.

[0027] According to an implementable manner of the first aspect of the present invention, determining the control terminal to be executed from each low-frequency wind turbine control terminal according to the stable control quantity includes:

[0028] Calculate the actual control power and the status value of each low-frequency wind turbine control terminal according to the following formula, and determine the control terminal to be executed according to the obtained status value calculation result:

[0029]

[0030]

[0031] In the formula, P C represents the actual control power, the value of P C is equal to the sum of the operating powers of all control terminals to be executed, Dp represents the stable control quantity, U i represents the status value of the i-th low-frequency wind turbine control terminal, n is the number of low-frequency wind turbine control terminals, U i = 1 indicates that the corresponding low-frequency wind turbine control terminal is the control terminal to be executed, and U i = 0 indicates that the corresponding low-frequency wind turbine control terminal is not the control terminal to be executed, represents finding the minimum value of the difference between the actual control power and the stable control quantity.

[0032] The second aspect of the present invention provides a stable control device applicable to a low-frequency AC power transmission system, including:

[0033] A memory for storing instructions, wherein the instructions are used to implement the stable control method applicable to the low-frequency AC power transmission system in any of the manners capable of being implemented as described above.

[0034] A processor for executing the instructions in the memory.

[0035] The third aspect of the present invention provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the stable control method applicable to the low-frequency AC power transmission system in any of the manners capable of being implemented as described above.

[0036] The fourth aspect of the present invention provides a stable control device applicable to a low-frequency AC power transmission system, where the low-frequency AC power transmission system transmits power to a power grid with industrial frequency through an inverter, and the device includes:

[0037] An acquisition module for acquiring operation information; the operation information includes the power transmission frequency of the industrial-frequency system, the power transmission frequency of the low-frequency AC system, the low-frequency transmission power, the maximum controllable amount, and the operation power of each control terminal of the low-frequency wind turbines.

[0038] A determination module for determining the corresponding power loss amount and the faulty line when a tripping fault occurs in the receiving-end line of the low-frequency AC power transmission system, selecting a target control strategy according to the faulty line, and obtaining the setting coefficient of the target control strategy; the setting coefficient includes an industrial-frequency generator tripping coefficient and an industrial-frequency generator tripping base value.

[0039] A calculation module for calculating the corresponding stable control amount according to the power transmission frequency of the industrial-frequency system, the power transmission frequency of the low-frequency AC system, the power loss amount, and the setting coefficient.

[0040] An execution module for comparing the magnitudes of the calculated stable control amount, the low-frequency transmission power, and the maximum controllable amount, and executing corresponding safety and stability control measures according to the obtained comparison result.

[0041] Among them, the safety and stability control measures include:

[0042] When the stable control amount is greater than the low-frequency transmission power, the inverter control system locks the inverter and issues an alarm of insufficient control amount.

[0043] When the stable control amount is not greater than the low-frequency transmission power and is greater than the maximum controllable amount, the inverter control system locks the inverter.

[0044] When the stable control amount is not greater than the maximum controllable amount, determine the control terminal to be executed from each low-frequency wind turbine control terminal according to the stable control amount, and send a control instruction to the control terminal to be executed so that the control terminal to be executed cuts off the corresponding wind turbine.

[0045] According to an implementable manner of the fourth aspect of the present invention, the determining module includes:

[0046] A matching unit, configured to match a corresponding control strategy from a preset strategy library according to the faulty line as the target control strategy; the preset strategy library stores a list of corresponding relationships between faulty lines and control strategies.

[0047] According to an implementable manner of the fourth aspect of the present invention, the calculating module includes:

[0048] A first calculation unit, configured to calculate a frequency conversion coefficient of a stable control generator tripping coefficient under low-frequency power transmission and a frequency conversion coefficient of a stable control generator tripping base value under low-frequency conditions according to the power frequency system transmission frequency and the low-frequency AC system transmission frequency;

[0049] A second calculation unit, configured to calculate the corresponding stable control amount according to the following formula:

[0050] Dp = K K ×Kset×(P - Pset×P K )

[0051] In the formula, Dp represents the stable control amount, P is the power loss amount, Kset is the power frequency generator tripping coefficient, Pset is the power frequency generator tripping base value, K K is the frequency conversion coefficient of the stable control generator tripping coefficient under low-frequency power transmission, and P K is the frequency conversion coefficient of the stable control generator tripping base value under low-frequency conditions.

[0052] According to an implementable manner of the fourth aspect of the present invention, the first calculation unit is specifically configured to:

[0053] Calculate the frequency conversion coefficient of the stable control generator tripping coefficient under low-frequency power transmission and the frequency conversion coefficient of the stable control generator tripping base value under low-frequency conditions according to the following formula:

[0054]

[0055] In the formula, f 0 is the power frequency system transmission frequency, f 1 is the low-frequency AC system transmission frequency, K is a preset adjustment coefficient, α is a preset first power value, and β is a preset second power value.

[0056] According to an implementable manner of the fourth aspect of the present invention, the first calculation unit is further specifically configured to:

[0057] Set K = 1, α = 1, β = 1.

[0058] According to an implementable manner of the fourth aspect of the present invention, the execution module includes:

[0059] A determination unit, configured to calculate the actual control power and the state values of each low-frequency wind turbine control terminal according to the following formula, and determine the control terminals to be executed according to the calculation results of the obtained state values:

[0060]

[0061]

[0062] In the formula, P C represents the actual control power, and the value of P C is equal to the sum of the operating powers of all control terminals to be executed. Dp represents the stable control quantity. U i represents the state value of the i-th low-frequency wind turbine control terminal. n is the number of low-frequency wind turbine control terminals. When U i = 1, it means that the corresponding low-frequency wind turbine control terminal is a control terminal to be executed. When U i = 0, it means that the corresponding low-frequency wind turbine control terminal is not a control terminal to be executed. represents finding the minimum value of the difference between the actual control power and the stable control quantity.

[0063] The fifth aspect of the present invention provides a stable control system applicable to a low-frequency AC power transmission system, including a frequency converter control system, each low-frequency wind turbine control terminal, and the stable control device applicable to the low-frequency AC power transmission system according to any one of the above implementable manners.

[0064] From the above technical solutions, it can be seen that the present invention has the following advantages:

[0065] When a tripping fault occurs in the receiving-end line of the low-frequency AC power transmission system, the present invention determines the corresponding power loss and the fault line, selects a target control strategy according to the fault line, and obtains the setting coefficient of the target control strategy; the setting coefficient includes a power frequency generator tripping coefficient and a power frequency generator tripping base value; calculates the corresponding stable control quantity according to the power frequency system transmission frequency, the low-frequency AC system transmission frequency, the power loss, and the setting coefficient; compares the calculated stable control quantity, the low-frequency transmission power, and the maximum controllable quantity, and executes corresponding safety and stability control measures according to the obtained comparison result; the present invention can effectively solve the safety and stability control problem of the low-frequency AC power transmission system, reduce the over-cut amount of the stable control, and improve the stable control effect. Brief Description of the Drawings

[0066] In order 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.

[0067] Figure 1 It is a flowchart of a stability control method applicable to a low-frequency AC power transmission system provided by an alternative embodiment of the present invention;

[0068] Figure 2 It is a flowchart corresponding to the safety and stability control measures provided by an alternative embodiment of the present invention;

[0069] Figure 3 It is provided by an alternative embodiment of the present invention for elaborating Figure 1 a specific example diagram of the method shown;

[0070] Figure 4 It is a structural connection block diagram of a stability control device applicable to a low-frequency AC power transmission system provided by an alternative embodiment of the present invention;

[0071] Figure 5 It is a control structure schematic diagram of a stability control system applicable to a low-frequency AC power transmission system provided by an alternative embodiment of the present invention;

[0072] Figure 6 It is a control structure schematic diagram of a stability control system applicable to a low-frequency AC power transmission system provided by another alternative embodiment of the present invention.

[0073] Reference Signs:

[0074] Figure 4 In the figure, 1 - acquisition module; 2 - determination module; 3 - calculation module; 4 - execution module. Detailed Embodiments

[0075] The embodiments of the present invention provide a stability control method, device and system applicable to a low-frequency AC power transmission system, which are used to solve the technical problem of how to effectively achieve the safety and stability control of the power output from the low-frequency AC power transmission system.

[0076] In order to make the object, features, and advantages of the present invention more obvious and understandable, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the following described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0077] The present invention provides a stable control method applicable to a low-frequency AC power transmission system.

[0078] Please refer to Figure 1 , Figure 1 which shows a flowchart of a stable control method applicable to a low-frequency AC power transmission system provided by an embodiment of the present invention.

[0079] A stable control method applicable to a low-frequency AC power transmission system provided by an embodiment of the present invention includes steps S1-S4.

[0080] Step S1, obtain operation information; the operation information includes the power transmission frequency of the power frequency system, the power transmission frequency of the low-frequency AC system, the low-frequency power transmission, the maximum controllable amount, and the operation power of each control terminal of the low-frequency wind turbine generator.

[0081] Among them, the power transmission frequency of the power frequency system, the power transmission frequency of the low-frequency AC system, the low-frequency power transmission, and the maximum controllable amount can be obtained from the low-frequency AC power transmission execution station. Further, the low-frequency AC power transmission execution station is connected to each control terminal of the low-frequency wind turbine generator, so as to obtain the operation power of each control terminal of the low-frequency wind turbine generator from the low-frequency AC power transmission execution station, and then send the obtained operation information to the device executing the method of the present application.

[0082] The control terminal of the low-frequency wind turbine generator is a terminal used to control the working state of the corresponding low-frequency wind turbine generator, and it can cut off or put into the corresponding wind turbine generator by controlling the switch of the circuit breaker corresponding to the wind turbine generator.

[0083] Step S2, when a tripping fault occurs in the receiving-end line of the low-frequency AC power transmission system, determine the corresponding power loss amount and the fault line, select a target control strategy according to the fault line, and obtain the setting coefficient of the target control strategy; the setting coefficient includes the power frequency generator tripping coefficient and the power frequency generator tripping base value.

[0084] As a specific implementation manner, a sensing device for sensing whether a line is faulty, such as a sensor, can be set, so as to determine the fault line according to the information transmitted by the sensing device.

[0085] As a specific implementation, a list of the correspondence between lines and power can be preset. When a faulty line is determined, the corresponding power is matched through this list as the power loss amount.

[0086] It should be noted that the faulty line and the power loss amount can also be obtained by using an existing line fault analysis system, so as to determine the faulty line and the power loss amount through interaction with the line fault analysis system.

[0087] In an implementable manner, the selecting the target control strategy according to the faulty line includes:

[0088] Matching a corresponding control strategy from a preset strategy library as the target control strategy according to the faulty line; the preset strategy library stores a list of the correspondence between faulty lines and control strategies.

[0089] In this embodiment, directly matching a corresponding control strategy from the preset strategy library as the target control strategy is simple and convenient.

[0090] Step S3, calculating a corresponding stability control amount according to the power transmission frequency of the power frequency system, the power transmission frequency of the low-frequency AC system, the power loss amount, and the fixed value setting coefficient.

[0091] In an implementable manner, the calculating a corresponding stability control amount according to the power transmission frequency of the power frequency system, the power transmission frequency of the low-frequency AC system, the power loss amount, and the fixed value setting coefficient includes:

[0092] Calculating a frequency conversion coefficient of the stability control generator tripping coefficient under low-frequency power transmission and a frequency conversion coefficient of the stability control generator tripping base value under low-frequency conditions according to the power transmission frequency of the power frequency system and the power transmission frequency of the low-frequency AC system;

[0093] Calculating a corresponding stability control amount according to the following formula:

[0094] Dp = K K × Kset × (P - Pset × P K )

[0095] In the formula, Dp represents the stability control amount, P is the power loss amount, Kset is the power frequency generator tripping coefficient, Pset is the power frequency generator tripping base value, K K is the frequency conversion coefficient of the stability control generator tripping coefficient under low-frequency power transmission, P K is the frequency conversion coefficient of the stability control generator tripping base value under low-frequency conditions.

[0096] In the embodiments of the present application, by using the frequency conversion relationship between the AC low frequency and the power frequency, the control strategy is converted, enabling accurate calculation of the stable control quantity, and improving the stable control effect and adaptability.

[0097] In an implementable manner, calculating the frequency conversion coefficient of the stable control generator tripping coefficient under low-frequency power transmission and the frequency conversion coefficient of the stable control generator tripping base value under low-frequency conditions includes:

[0098] Calculate the frequency conversion coefficient of the stable control generator tripping coefficient under low-frequency power transmission and the frequency conversion coefficient of the stable control generator tripping base value under low-frequency conditions according to the following formula:

[0099]

[0100] In the formula, f 0 is the power transmission frequency of the power frequency system, f 1 is the power transmission frequency of the low-frequency AC system, K is a preset adjustment coefficient, α is a preset first power value, and β is a preset second power value.

[0101] The frequency conversion coefficient of the stable control generator tripping coefficient under low-frequency power transmission and the frequency conversion coefficient of the stable control generator tripping base value under low-frequency conditions are both functions of the power transmission frequency of the power frequency system and the power transmission frequency of the low-frequency AC system. Among them, K, α, and β can be set according to actual situations. As a specific implementation method, set K = 1, α = 1, β = 1. As another specific implementation method, set K = 0.9, α = 2, β = 2.

[0102] Step S4, compare the magnitudes of the calculated stable control quantity, the low-frequency power transmission power, and the maximum controllable quantity, and execute corresponding secure and stable control measures according to the obtained comparison results.

[0103] Among them, as Figure 2 shown, the secure and stable control measures include:

[0104] When the stable control quantity is greater than the low-frequency power transmission power, lock the frequency converter through the frequency converter control system and issue an alarm for insufficient control quantity;

[0105] When the stable control quantity is not greater than the low-frequency power transmission power and is greater than the maximum controllable quantity, lock the frequency converter through the frequency converter control system;

[0106] When the stable control quantity is not greater than the maximum controllable quantity, determine the control terminals that need to be executed from each low-frequency wind turbine control terminal according to the stable control quantity, and send control instructions to the control terminals that need to be executed so that the control terminals that need to be executed cut off the corresponding wind turbines.

[0107] In a feasible implementation manner, determining the control terminals to be executed from each low-frequency wind turbine control terminal according to the stable control quantity includes:

[0108] Calculate the actual control power and the state values of each low-frequency wind turbine control terminal according to the following formula, and determine the control terminals to be executed according to the calculation results of the obtained state values:

[0109]

[0110]

[0111] In the formula, P C represents the actual control power, and the value of P C is equal to the sum of the operating powers of all the control terminals to be executed. Dp represents the stable control quantity, U i represents the state value of the i-th low-frequency wind turbine control terminal, n is the number of low-frequency wind turbine control terminals, and when U i = 1, it means that the corresponding low-frequency wind turbine control terminal is the control terminal to be executed; when U i = 0, it means that the corresponding low-frequency wind turbine control terminal is not the control terminal to be executed. represents finding the minimum value of the difference between the actual control power and the stable control quantity.

[0112] The above embodiments of the present invention can effectively solve the problem of the security and stability control of the power transmission of the low-frequency AC power transmission system, reduce the over-cut amount of the stability control, and improve the stability control effect.

[0113] To better illustrate the method of the present invention Figure 1 as shown, a specific example is described below.

[0114] For the low-frequency AC power transmission system as Figure 3 shown, it transmits the power of each fan through a low-frequency AC power transmission line and then transmits the power to the power frequency power grid through an inverter. The low-frequency AC power transmission system is configured with a corresponding stability control system, which includes a stability control master station and a low-frequency AC power transmission execution station. The control terminals corresponding to the first fan, the second fan, and the third fan are connected by the low-frequency AC power transmission execution station. The parameters are as follows:

[0115] f 0 = 50Hz, f 1 = 25Hz, P 1 = 15MW, P 2 = 20MW, P 3 = 35MW, P s = 70MW, P max = 70MW

[0116] Among them, f 0is the power transmission frequency of the power frequency system, f 1 is the power transmission frequency of the low-frequency AC system, P 1 is the operating power of the control terminal corresponding to the first fan, P 2 is the operating power of the control terminal corresponding to the second fan, P 3 is the operating power of the control terminal corresponding to the third fan, P s is the low-frequency power transmission power, P max is the maximum controllable amount.

[0117] Case 1: A tripping fault occurs on Line 1, and the power loss amount P = 200 MW. The calculated stable control amount is:

[0118]

[0119] Since the calculated stable control amount is greater than the low-frequency power transmission power, the frequency converter is locked by the frequency converter control system, and an alarm of insufficient control amount is issued.

[0120] Case 2: A tripping fault occurs on Line 1, and the power loss amount P = 100 MW. The calculated stable control amount is:

[0121]

[0122] Since the stable control amount is less than the maximum controllable amount, the actual control power and the state values of the corresponding control terminals are calculated through the following expressions:

[0123]

[0124] It is calculated that P c = 50 MW, U 1 = 1, U 2 = 0, U 3 = 1. At this time, it is determined that the control terminals corresponding to the first fan and the third fan are the control terminals to be executed, and control instructions are sent to each control terminal to be executed to cut off the corresponding fans.

[0125] Case 3: The communication between the control terminal of the third fan and the low-frequency power transmission execution station is interrupted. At this time, the low-frequency power transmission power P s = 70 MW, and the maximum controllable amount P max = 35 MW. A tripping fault occurs on Line 1, and the power loss amount P = 100 MW. The calculated stable control amount is:

[0126]

[0127] Since the calculated stable control amount is greater than the maximum controllable amount but less than the low-frequency power transmission power, the frequency converter is locked by the frequency converter control system at this time.

[0128] The present invention also provides a stability control device applicable to a low-frequency AC power transmission system, comprising:

[0129] a memory for storing instructions; wherein, the instructions are used to implement the stability control method applicable to the low-frequency AC power transmission system described in any one of the above embodiments;

[0130] a processor for executing the instructions in the memory.

[0131] The present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the stability control method applicable to the low-frequency AC power transmission system described in any one of the above embodiments.

[0132] The present invention also provides a stability control device applicable to a low-frequency AC power transmission system, and this device can be used to execute the stability control method applicable to the low-frequency AC power transmission system described in any one of the above embodiments of the present invention.

[0133] Please refer to Figure 4 , Figure 4 , which shows a structural connection block diagram of a stability control device applicable to a low-frequency AC power transmission system provided by an embodiment of the present invention.

[0134] A stability control device applicable to a low-frequency AC power transmission system provided by an embodiment of the present invention, comprising:

[0135] an acquisition module 1 for acquiring operation information; the operation information includes the power transmission frequency of the power frequency system, the power transmission frequency of the low-frequency AC system, the low-frequency power transmission, the maximum controllable amount, and the operation power of each control terminal of the low-frequency wind turbines;

[0136] a determination module 2 for determining the corresponding power loss amount and the faulty line when a tripping fault occurs in the receiving-end line of the low-frequency AC power transmission system, selecting a target control strategy according to the faulty line, and acquiring the setting coefficient of the target control strategy; the setting coefficient includes a power frequency generator tripping coefficient and a power frequency generator tripping base value;

[0137] a calculation module 3 for calculating the corresponding stability control amount according to the power transmission frequency of the power frequency system, the power transmission frequency of the low-frequency AC system, the power loss amount, and the setting coefficient;

[0138] an execution module 4 for comparing the magnitudes of the calculated stability control amount, the low-frequency power transmission, and the maximum controllable amount, and executing corresponding safety and stability control measures according to the obtained comparison result;

[0139] wherein, the safety and stability control measures include:

[0140] When the stable control quantity is greater than the low-frequency power transmission power, the frequency converter control system locks the frequency converter and issues an alarm for insufficient control quantity;

[0141] When the stable control quantity is not greater than the low-frequency power transmission power and is greater than the maximum controllable quantity, the frequency converter control system locks the frequency converter;

[0142] When the stable control quantity is not greater than the maximum controllable quantity, the control terminal to be executed is determined from each low-frequency wind turbine control terminal according to the stable control quantity, and a control instruction is sent to the control terminal to be executed so that the control terminal to be executed cuts off the corresponding wind turbine.

[0143] In an implementable manner, the determining module 2 includes:

[0144] A matching unit, configured to match a corresponding control strategy from a preset strategy library as the target control strategy according to the faulty line; the preset strategy library stores a list of the corresponding relationships between faulty lines and control strategies.

[0145] In an implementable manner, the calculating module 3 includes:

[0146] A first calculation unit, configured to calculate a frequency conversion coefficient of a stable control generator tripping coefficient under low-frequency power transmission and a frequency conversion coefficient of a stable control generator tripping base value under low-frequency conditions according to the power frequency system transmission frequency and the low-frequency AC system transmission frequency;

[0147] A second calculation unit, configured to calculate the corresponding stable control quantity according to the following formula:

[0148] Dp = K K ×Kset×(P - Pset×P K )

[0149] In the formula, Dp represents the stable control quantity, P is the power loss quantity, Kset is the power frequency generator tripping coefficient, Pset is the power frequency generator tripping base value, K K is the frequency conversion coefficient of the stable control generator tripping coefficient under low-frequency power transmission, and P K is the frequency conversion coefficient of the stable control generator tripping base value under low-frequency conditions.

[0150] In an implementable manner, the first calculation unit is specifically configured to:

[0151] Calculate the frequency conversion coefficient of the stable control generator tripping coefficient under low-frequency power transmission and the frequency conversion coefficient of the stable control generator tripping base value under low-frequency conditions according to the following formula:

[0152]

[0153] Wherein, f0 is the power frequency system transmission frequency, f1 is the low-frequency AC system transmission frequency, K is a preset adjustment coefficient, α is a preset first power value, and β is a preset second power value.

[0154] In an implementable manner, the first calculation unit is further specifically configured to:

[0155] Set K = 1, α = 1, β = 1.

[0156] In an implementable manner, the execution module 4 includes:

[0157] A determination unit, configured to calculate the actual control power and the state values of each low-frequency wind turbine control terminal according to the following formula, and determine the control terminals to be executed according to the obtained state value calculation results:

[0158]

[0159]

[0160] In the formula, P C represents the actual control power, and the value of P C is equal to the sum of the operating powers of all control terminals to be executed. Dp represents the stable control quantity. U i represents the state value of the i-th low-frequency wind turbine control terminal, n is the number of low-frequency wind turbine control terminals, and when U i = 1, it means that the corresponding low-frequency wind turbine control terminal is a control terminal to be executed. When U i = 0, it means that the corresponding low-frequency wind turbine control terminal is not a control terminal to be executed. represents finding the minimum value of the difference between the actual control power and the stable control quantity.

[0161] The present invention further provides a stable control system applicable to a low-frequency AC power transmission system, including a frequency converter control system, each low-frequency wind turbine control terminal, and a stable control device applicable to a low-frequency AC power transmission system as described in any of the above implementable manners.

[0162] When the number of low-frequency wind turbine control terminals is small (generally less than 10), the control structure as shown in Figure 5 can be adopted. When the number of low-frequency wind turbine control terminals is large (generally not less than 10), the control structure as shown in Figure 6 can be adopted. Among them, the control master station shown in Figure 5 , Figure 6 serves as a stable control device applicable to a low-frequency AC power transmission system. The control master station establishes a communication connection with a low-frequency AC power transmission execution station, and then the low-frequency AC power transmission execution station connects to the frequency converter control system and each low-frequency wind turbine control terminal T 1,T 2 ,T 3 ,...,T n The control master station can obtain operation information through the low-frequency AC power transmission execution station, and control each low-frequency wind turbine control terminal and the frequency converter control system.

[0163] Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working processes of the above-described devices, systems, and modules can refer to the corresponding processes in the foregoing method embodiments, and the specific beneficial effects of the above-described devices, systems, and modules can refer to the corresponding beneficial effects in the foregoing method embodiments, which will not be elaborated herein.

[0164] In several embodiments provided in the present application, it should be understood that the disclosed devices, systems, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the modules is only a logical function division, and there may be other division methods in actual implementation. For example, multiple modules or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections between each other can be through some interfaces, and the indirect couplings or communication connections of the devices or modules can be in electrical, mechanical, or other forms.

[0165] The modules described as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical modules, that is, they can be located in one place or distributed to multiple network modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0166] In addition, in each embodiment of the present invention, the functional modules can be integrated in a processing module, or each module can exist physically alone, or two or more modules can be integrated in one module. The above-integrated modules can be implemented in the form of hardware or in the form of software functional modules.

[0167] When the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer system (which may be a personal computer, a server, or a network system, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0168] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of various embodiments of the present invention.

Claims

1. A stability control method applicable to a low-frequency AC power transmission system, where the low-frequency AC power transmission system transmits power to the power frequency power grid through an inverter. Characterized in that: The method includes: Obtaining operation information; the operation information includes the power transmission frequency of the power frequency system, the power transmission frequency of the low-frequency AC system, the low-frequency transmission power, the maximum controllable amount, and the operation power of each low-frequency wind turbine control terminal. When a tripping fault occurs in the receiving-end line of the low-frequency AC power transmission system, determining the corresponding power loss amount and the faulty line, selecting a target control strategy according to the faulty line, and obtaining the setting coefficient of the target control strategy; the setting coefficient includes the power frequency generator tripping coefficient and the power frequency generator tripping base value. Calculating the corresponding stability control amount according to the power transmission frequency of the power frequency system, the power transmission frequency of the low-frequency AC system, the power loss amount, and the setting coefficient. Comparing the calculated stability control amount, the low-frequency transmission power, and the maximum controllable amount, and implementing corresponding safety and stability control measures according to the obtained comparison result. Among them, the safety and stability control measures include: When the stability control amount is greater than the low-frequency transmission power, locking the inverter through the inverter control system and issuing an alarm of insufficient control amount. When the stability control amount is not greater than the low-frequency transmission power and is greater than the maximum controllable amount, locking the inverter through the inverter control system. When the stability control amount is not greater than the maximum controllable amount, determining the control terminals to be executed from each low-frequency wind turbine control terminal according to the stability control amount, and sending a control instruction to the control terminals to be executed so that the control terminals to be executed cut off the corresponding wind turbines. The calculating the corresponding stability control amount according to the power transmission frequency of the power frequency system, the power transmission frequency of the low-frequency AC system, the power loss amount, and the setting coefficient includes: Calculating the frequency conversion coefficient of the stability control generator tripping coefficient under low-frequency power transmission and the frequency conversion coefficient of the stability control generator tripping base value under low-frequency conditions according to the power transmission frequency of the power frequency system and the power transmission frequency of the low-frequency AC system. Calculating the corresponding stability control amount according to the following formula: ； Wherein, represents the stable control quantity, is the power loss quantity, is the power frequency generator tripping coefficient, is the power frequency generator tripping base value, is the frequency conversion coefficient of the stable control generator tripping coefficient under low-frequency power transmission, is the frequency conversion coefficient of the stable control generator tripping base value under low-frequency conditions; The calculating the frequency conversion coefficient of the stability control generator tripping coefficient under low-frequency power transmission and the frequency conversion coefficient of the stability control generator tripping base value under low-frequency conditions includes: Calculating the frequency conversion coefficient of the stability control generator tripping coefficient under low-frequency power transmission and the frequency conversion coefficient of the stability control generator tripping base value under low-frequency conditions according to the following formula: ； In the formula, is the power frequency system transmission frequency, is the low-frequency AC system transmission frequency, is a preset adjustment coefficient, is a preset first power value, is a preset second power value.

2. The stability control method applicable to a low-frequency AC power transmission system according to claim 1, Characterized in that: The selecting the target control strategy according to the faulty line includes: Matching the corresponding control strategy from the preset strategy library as the target control strategy according to the faulty line; the preset strategy library stores a list of the corresponding relationship between the faulty line and the control strategy.

3. The stability control method applicable to a low-frequency AC power transmission system according to claim 1, Characterized in that: The calculating the frequency conversion coefficient of the stability control generator tripping coefficient under low-frequency power transmission and the frequency conversion coefficient of the stability control generator tripping base value under low-frequency conditions further includes: Set .

4. The stability control method applicable to a low-frequency AC power transmission system according to claim 1, characterized in that, determining the control terminals to be executed from each low-frequency wind turbine control terminal according to the stability control quantity includes: calculating the actual control power and the state values of each low-frequency wind turbine control terminal according to the following formula, and determining the control terminals to be executed according to the obtained state value calculation results: ； Wherein, represents the actual control power, The value of which is equal to the sum of the operating powers of all control terminals to be executed, represents the stable control quantity, represents the th state value of the low-frequency wind turbine control terminal, is the number of low-frequency wind turbine control terminals, When it is, it means that the corresponding low-frequency wind turbine control terminal is a control terminal to be executed, When it is, it means that the corresponding low-frequency wind turbine control terminal is not a control terminal to be executed, represents finding the minimum value of the difference between the actual control power and the stable control quantity.

5. A stability control device applicable to a low-frequency AC power transmission system, characterized in that, including: a memory for storing instructions; wherein, the instructions are used to implement the stability control method applicable to the low-frequency AC power transmission system according to any one of claims 1-4; a processor for executing the instructions in the memory.

6. A computer-readable storage medium, characterized in that, a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, it implements the stability control method applicable to the low-frequency AC power transmission system according to any one of claims 1-4.

7. A stability control device applicable to a low-frequency AC power transmission system, wherein the low-frequency AC power transmission system transmits power to a power frequency power grid through an inverter, characterized in that, the device includes: an acquisition module for acquiring operation information; the operation information includes the power transmission frequency of the power frequency system, the power transmission frequency of the low-frequency AC system, the low-frequency power transmission, the maximum controllable quantity, and the operation power of each low-frequency wind turbine control terminal; a determination module for determining the corresponding power loss and the fault line when a trip fault occurs in the receiving-end line of the low-frequency AC power transmission system, selecting a target control strategy according to the fault line, and obtaining the setting coefficient of the target control strategy; the setting coefficient includes a power frequency generator tripping coefficient and a power frequency generator tripping base value; a calculation module for calculating the corresponding stability control quantity according to the power transmission frequency of the power frequency system, the power transmission frequency of the low-frequency AC system, the power loss, and the setting coefficient; an execution module for comparing the calculated stability control quantity, the low-frequency power transmission, and the maximum controllable quantity, and executing corresponding safety and stability control measures according to the obtained comparison result; wherein, the safety and stability control measures include: when the stability control quantity is greater than the low-frequency power transmission, locking the inverter through the inverter control system and sending an alarm of insufficient control quantity; when the stability control quantity is not greater than the low-frequency power transmission and is greater than the maximum controllable quantity, locking the inverter through the inverter control system; when the stability control quantity is not greater than the maximum controllable quantity, determining the control terminals to be executed from each low-frequency wind turbine control terminal according to the stability control quantity, and sending a control instruction to the control terminals to be executed so that the control terminals to be executed cut off the corresponding wind turbines; the calculation module includes: a first calculation unit for calculating the frequency conversion coefficient of the stability control generator tripping coefficient under low-frequency power transmission and the frequency conversion coefficient of the stability control generator tripping base value under low-frequency conditions according to the power transmission frequency of the power frequency system and the power transmission frequency of the low-frequency AC system; a second calculation unit for calculating the corresponding stability control quantity according to the following formula: ； In the formula, represents the stable control quantity, is the power loss quantity, is the power frequency generator tripping coefficient, is the power frequency generator tripping base value, is the frequency conversion coefficient of the stable control generator tripping coefficient under low-frequency power transmission, is the frequency conversion coefficient of the stable control generator tripping base value under low-frequency conditions; The first calculation unit is specifically configured to: Calculate the frequency transformation coefficient of the stable control generator tripping coefficient under low-frequency power transmission and the frequency transformation coefficient of the stable control generator tripping base value under low-frequency conditions according to the following formula: ； Wherein, is the power frequency system transmission frequency; is the low-frequency AC system transmission frequency; is a preset adjustment coefficient; is a preset first power value; is a preset second power value.

8. A stable control system applicable to a low-frequency AC power transmission system, characterized in that it includes an inverter control system, control terminals of each low-frequency wind turbine generator, and a stable control device applicable to a low-frequency AC power transmission system as described in claim 7.

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