A wind farm reactive power control method considering single wind turbine generator terminal voltage

Abstract

The application provides a wind farm reactive power control method considering single wind turbine generator terminal voltage, and belongs to the technical field of wind farm voltage and reactive power automatic regulation. The method comprises the following steps: when each regulation period arrives, the single-machine reactive power adjustment amount of each wind turbine generator is determined based on the current terminal voltage, and the reactive power regulation target value of the single wind turbine generator under the condition of the current terminal voltage out of limit is calculated; then, according to whether the low-voltage bus voltage of the wind farm and whether the grid-connected point bus voltage of the wind farm are out of limit, the single-machine reactive power adjustment amount of each wind turbine generator is updated and the reactive power regulation target value is calculated; and based on the single-machine reactive power adjustment amount, the total reactive power adjustable amount of the wind farm is calculated to realize the reactive power control of the wind farm. The single wind turbine generator terminal voltage is preferentially ensured to be within the qualified range, and under the premise that the single wind turbine generator terminal voltage is qualified, the grid-connected point voltage of the wind farm is controlled to reach the target value issued by dispatching, so that the safety and reliability of the wind farm operation are improved.

Description

Technical Field

[0001] This invention belongs to the field of automatic voltage and reactive power regulation technology for wind farms, and specifically relates to a method for reactive power control of wind farms that takes into account the terminal voltage of a single wind turbine unit. Background Technology

[0002] The reactive power source of a wind farm includes wind turbine generators and reactive power compensation devices. Wind farms should make full use of the reactive power capacity and regulation capabilities of wind turbine generators. When the reactive power capacity of wind turbine generators cannot meet the system voltage regulation needs, appropriate capacity reactive power compensation devices should be centrally installed at the wind farm, and dynamic reactive power compensation devices should be installed if necessary.

[0003] Currently, the reactive power and voltage control system of wind farms calculates the reactive power regulation amount based on the grid connection point voltage target issued by the dispatch center and sends it to the wind turbine monitoring system. The wind turbine monitoring system then distributes the reactive power regulation amount to each wind turbine. Because the wind turbine monitoring system generally does not consider the terminal voltage of each wind turbine when distributing the reactive power regulation amount, situations frequently occur where, although the grid connection point voltage is within acceptable limits after regulation, the wind turbine terminal voltage exceeds the limit, affecting the safe operation of the wind farm's voltage. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and propose a reactive power control method for wind farms that considers the terminal voltage of individual wind turbine units. This invention can fully consider the terminal voltage of each wind turbine unit when performing reactive power and voltage control in wind farms, thereby improving the safety and reliability of wind farm operation.

[0005] This invention proposes a reactive power control method for wind farms that considers the terminal voltage of a single wind turbine, comprising:

[0006] At the arrival of each adjustment cycle, based on the current terminal voltage of each wind turbine in the wind farm, the reactive power adjustment amount of each wind turbine is determined, and the reactive power adjustment target value of the wind turbine under the condition that the current terminal voltage exceeds the limit is calculated.

[0007] When the voltage of the low-voltage bus of the wind farm exceeds the upper limit and the reactive power reduction of the entire wind farm is not blocked, or when the voltage of the low-voltage bus of the wind farm exceeds the lower limit and the reactive power increase of the entire wind farm is not blocked, update the single-unit reactive power adjustment amount of each wind turbine and calculate the reactive power adjustment target value of each wind turbine.

[0008] When the voltage of the bus at the grid connection point of the wind farm exceeds the upper limit and the reactive power reduction of the entire field is not blocked, or when the voltage of the bus at the grid connection point of the wind farm exceeds the lower limit and the reactive power increase of the entire field is not blocked, the reactive power adjustment target value of each wind turbine is updated.

[0009] Based on the single-unit reactive power adjustment of each wind turbine, the total reactive power adjustable amount of the wind farm is calculated to achieve reactive power control of the wind farm.

[0010] In a specific embodiment of the present invention, the step of determining the reactive power adjustment amount of each wind turbine based on the current terminal voltage of each wind turbine in the wind farm, and calculating the reactive power adjustment target value of the wind turbine under the condition that the current terminal voltage exceeds the limit, includes:

[0011] 1) Initialize the full-field reactive power increase blocking signal Q inc_lock =0 indicates that the overall reactive power increase is not blocked; initialize the overall reactive power decrease blocking signal Q. dec_lock =0 indicates that the entire field's reactive power reduction is not locked;

[0012] 2) By determining the current terminal voltage of each wind turbine, the reactive power adjustment of a single wind turbine is determined, and the target reactive power adjustment value for a single wind turbine under the condition that the current terminal voltage exceeds the limit is calculated; where:

[0013] 2-1) If there exists a wind turbine i that satisfies U gen_i >U gen_max_i Then let Q gen_set_i =Q gen_i -Q gen_step_i ;

[0014] Let Q inc_lock =1 indicates that the reactive power increase is locked across the entire field; the reactive power increase of wind turbine i is Q. gen_inc_i =0; where the subscript i represents the wind turbine serial number, U gen_i U is the current terminal voltage of wind turbine i. gen_max_i Q represents the upper limit of the terminal voltage of wind turbine i. gen_set_i Let Q be the target value for reactive power regulation of wind turbine unit i. gen_step_i Q is the single-unit reactive power regulation step size of wind turbine i. gen_i For the reactive power of wind turbine i;

[0015] 2-2) If there exists a wind turbine i that satisfies U gen_i <U gen_min_i Then let Q gen_set_i =Q gen_i +Q gen_step_i ;

[0016] Let Q dec_lock =1 indicates that the reactive power reduction is locked across the entire field; the reactive power reduction of wind turbine i is Q. gen_dec_i =0; where, U gen_min_i This is the lower limit of the terminal voltage of wind turbine unit i;

[0017] 2-3) If there exists a wind turbine i that satisfies U gen_max_warn_i ≤U gen_i ≤U gen_max_i Then let Q gen_inc_i =0; where, U gen_max_warn_i This is the upper limit of the warning voltage at the turbine terminal of wind turbine i;

[0018] 2-4) If there exists a wind turbine i that satisfies U gen_min_i ≤U gen_i ≤U gen_min_warn_i Then let Q gen_dec_i =0; where, U gen_min_warn_i This is the lower warning limit for the terminal voltage of wind turbine unit i;

[0019] 2-5) If there exists a wind turbine i that satisfies U gen_min_warn_i <U gen_i <U gen_max_warn_i Then let the reactive power limit of wind turbine i be Q. gen_max_i for:

[0020]

[0021] Among them, P gen_i For the single-unit active power of wind turbine i, COS gen_i Here is the power factor limit for wind turbine unit i.

[0022] Then according to Q gen_max_i Make a judgment:

[0023] If Q gen_max_i >Q gen_i Then let Q gen_inc_i =Q gen_max_i -Q gen_i ;

[0024] If Q gen_max_i ≤Q gen_i Then let Q gen_inc_i =0;

[0025] If Q gen_i >(-1)*Q gen_max_i Then let Q gen_dec_i =Q gen_i +Q gen_max_i ;

[0026] If Q gen_i ≤(-1)*Q gen_max_i Then let Q gen_dec_i =0.

[0027] In one specific embodiment of the present invention, the method further includes:

[0028] If U low_bus >Ulow_bus_max And Q dec_lock =0, then the low-voltage bus voltage of the wind farm exceeds the upper limit, let Q inc_lock =1, so that the reactive power adjustment Q of each wind turbine unit is increased. gen_inc_i =0, based on the current terminal voltage of each wind turbine, determine the reactive power regulation target value for each wind turbine, where:

[0029] If U gen_i >U gen_max_1st_i Then let Q gen_set_i =Q gen_i -Q gen_step_i ;

[0030] If U gen_max_2nd_i ≤U gen_i ≤U gen_max_1st_i Then let Q gen_set_i =Q gen_i -Q gen_step_i / 2;

[0031] If U gen_i <U genmax_2nd_i Then let Q gen_set_i =Q gen_i ;

[0032] Among them, U low_bus U is the low-voltage bus voltage of the wind farm. low_bus_max U is the upper limit of the low-voltage bus voltage of the wind farm. gen_max_1st_i U is the upper limit of the primary regulating voltage at the turbine terminal of wind turbine i. gen_max_2nd_i This is the upper limit of the secondary regulation voltage at the turbine terminal of wind turbine unit i.

[0033] In one specific embodiment of the present invention, the method further includes:

[0034] If U low_bus <U low_bus_min And Q inc_lock =0, then the low-voltage bus voltage of the wind farm exceeds the lower limit, let Q dec_lock =1, so that the reactive power reduction Q of each wind turbine unit is reduced. gen_dec_i =0, based on the current terminal voltage of each wind turbine, determine the reactive power regulation target value for each wind turbine, where:

[0035] If U gen_i <U gen_min_1st_i Then let Q gen_set_i =Q gen_i +Q gen_step_i ;

[0036] If U gen_min_1st_i ≤U gen_i ≤U gen_min_2nd_i Then let Q gen_set_i=Q gen_i +Q gen_step_i / 2;

[0037] If U gen_i >U gen_min_2nd_i Then let Q gen_set_i =Q gen_i ;

[0038] Among them, U low_bus_min U is the lower limit of the low-voltage bus voltage in the wind farm. gen_min_1st_i U is the lower limit of the primary regulating voltage at the turbine terminal of wind turbine i. gen_min_2nd_i This is the lower limit of the secondary regulation voltage at the turbine terminal of wind turbine unit i.

[0039] In one specific embodiment of the present invention, the method further includes:

[0040] Calculate the upper limit of the acceptable bus voltage at the grid connection point, U. high_bus_max_set =U high_bus_set +U high_bus_dead ;

[0041] Calculate the lower limit of the qualified bus voltage U at the grid connection point high_bus_min_set =U high_bus_set -U high_bus_dead ;

[0042] Among them, U high_bus_set U is the target value of the bus voltage at the grid connection point of the wind farm. high_bus_dead To control dead zones;

[0043] Then determine:

[0044] If U high_bus_max_set >U high_bus_max Then let U high_bus_max_set =U high_bus_max ;

[0045] If U high_bus_min_set <U high_bus_min Then let U high_bus_min_set =U high_bus_min ;

[0046] Among them, U high_bus_max U is the upper limit of the bus voltage at the grid connection point of the wind farm. high_bus_min This is the lower limit of the bus voltage at the grid connection point of the wind farm.

[0047] In one specific embodiment of the present invention, the method further includes:

[0048] If the bus voltage at the grid connection point U high_bus >U high_bus_max_set And Q dec_lock =0, then the voltage of the grid connection point bus exceeds the upper limit. Determine the reactive power regulation target value for each wind turbine, where:

[0049] If U gen_i >U gen_max_1st_i Then let Q gen_set_i =Q gen_i -Q gen_step_i ;

[0050] If U gen_max_2nd_i ≤U gen_i ≤U gen_max_1st_i Then let Q gen_set_i =Q gen_i -Q gen_step_i / 2;

[0051] If U gen_i <U genmax_2nd_i Then let Q gen_set_i =Q gen_i .

[0052] In one specific embodiment of the present invention, the method further includes:

[0053] If the bus voltage at the grid connection point U high_bus <U high_bus_max_set And Q inc_lock =0, then the voltage of the grid connection point bus falls below the lower limit. Determine the reactive power regulation target value for each wind turbine, where:

[0054] If U gen_i <U gen_min_1st_i Then let Q gen_set_i =Q gen_i +Q gen_step_i ;

[0055] If U gen_min_1st_i ≤U gen_i ≤U gen_min_2nd_i Then let Q gen_set_i =Q gen_i +Q gen_step_i / 2;

[0056] If U gen_i >U gen_min_2nd_i Then let Q gen_set_i =Q gen_i .

[0057] In one specific embodiment of the present invention, calculating the total reactive power adjustable amount of the wind farm includes:

[0058] If Q inc_lock =1, then Q inc_all =0;

[0059] If Q inc_lock =0, then:

[0060]

[0061] If Q dec_lock =1, then Q dec_all =0;

[0062] If Q dec_lock =0, then:

[0063]

[0064] Where N is the total number of wind turbine units; Q inc_all To increase reactive power across the entire field, Q dec_all The amount of reactive power reduced across the entire field.

[0065] The features and beneficial effects of the method of this invention are as follows:

[0066] This invention prioritizes ensuring that the terminal voltage of individual wind turbines remains within acceptable limits when performing reactive power control in wind farms. Only after guaranteeing the acceptable terminal voltage of individual wind turbines is the grid connection voltage of the wind farm controlled to reach the target value issued by the dispatch center. Simultaneously, by setting a reactive power adjustment step size for each wind turbine, this invention limits the magnitude of each adjustment, ensuring a smooth transition between the wind turbine terminal voltage and the grid connection voltage throughout the adjustment process. This improves the safety and reliability of wind farm operation while achieving reactive power control. Attached Figure Description

[0067] Figure 1 This is an overall flowchart of a wind farm reactive power control method that considers the terminal voltage of a single wind turbine in this embodiment. Detailed Implementation

[0068] This invention proposes a reactive power control method for wind farms that considers the terminal voltage of a single wind turbine unit. The following is a detailed description in conjunction with the accompanying drawings and specific embodiments.

[0069] This embodiment proposes a reactive power control method for wind farms that considers the terminal voltage of a single wind turbine, including:

[0070] At the arrival of each adjustment cycle, based on the current terminal voltage of each wind turbine in the wind farm, the reactive power adjustment amount of each wind turbine is determined, and the reactive power adjustment target value of the wind turbine under the condition that the current terminal voltage exceeds the limit is calculated.

[0071] When the voltage of the low-voltage bus of the wind farm exceeds the upper limit and the reactive power reduction of the entire wind farm is not blocked, or when the voltage of the low-voltage bus of the wind farm exceeds the lower limit and the reactive power increase of the entire wind farm is not blocked, update the single-unit reactive power adjustment amount of each wind turbine and calculate the reactive power adjustment target value of each wind turbine.

[0072] When the voltage of the bus at the grid connection point of the wind farm exceeds the upper limit and the reactive power reduction of the entire field is not blocked, or when the voltage of the bus at the grid connection point of the wind farm exceeds the lower limit and the reactive power increase of the entire field is not blocked, the reactive power adjustment target value of each wind turbine is updated.

[0073] Based on the single-unit reactive power adjustment of each wind turbine, the total reactive power adjustable amount of the wind farm is calculated to achieve reactive power control of the wind farm.

[0074] In a specific embodiment of the present invention, the overall process of the wind farm reactive power control method considering the terminal voltage of a single wind turbine is as follows: Figure 1 As shown, it includes the following steps:

[0075] 1) Configure the upper limit of the terminal voltage U for each wind turbine. gen_max_i Terminal voltage lower limit U gen_min_i Terminal voltage warning upper limit U gen_max_warn_i Terminal voltage warning lower limit U gen_min_warn_i Terminal-level regulating voltage upper limit U gen_max_1st_i Upper limit of the secondary regulating voltage U at the machine terminal gen_max_2nd_i The lower limit of the primary regulating voltage U at the machine terminal gen_min_1st_i The lower limit of the secondary regulating voltage U at the machine terminal gen_min_2nd_i Single-unit reactive power adjustment step size (i.e., the maximum allowable value of reactive power adjustment for a single wind turbine unit in each step) Q gen_step_i Single-unit power factor limit (COS) gen_i Where the subscript i represents the wind turbine serial number, i = 1, ..., N, and N represents the total number of wind turbines; set the upper limit U of the low-voltage bus voltage of the wind farm. low_bus_max Lower limit of low-voltage bus voltage U in wind farm low_bus_min Upper limit of bus voltage at the grid connection point of the wind farm, U high_bus_max Lower limit of bus voltage at wind farm grid connection point U high_bus_min Control dead zone U high_bus_dead .

[0076] 2) At the arrival of each adjustment cycle, obtain the current terminal voltage U of each wind turbine from the wind turbine monitoring system. gen_i Standalone active P gen_i Single-machine reactive power Q gen_i Standalone adjustable reactive power state C gen_i The low-voltage bus voltage U of the wind farm is obtained from the local monitoring system of the wind farm's booster station. low_bus Wind farm grid connection point bus voltage U high_bus The target value U of the bus voltage at the wind farm's grid connection point is obtained from the upper-level reactive power and voltage control master station. high_bus_set .

[0077] Let the target value of reactive power regulation of wind turbine unit i be Q.gen_set_i The reactive power adjustment of a single unit is Q. gen_inc_i The single-unit reactive power reduction is Q. gen_dec_i The overall reactive power increase blocking signal is Q. inc_lock The overall reactive power reduction blocking signal is Q. dec_lock The total reactive power increase is Q. inc_all The total reactive power reduction is Q. dec_all .

[0078] 3) Based on the current terminal voltage of each wind turbine in the wind farm, determine the reactive power adjustment for each wind turbine, and calculate the target reactive power adjustment value for the wind turbine under the condition that the current terminal voltage exceeds the limit; the specific steps are as follows:

[0079] 3-1) Initialize Q inc_lock =0 indicates that the reactive power increase across the entire field is not interlocked; initialize Q. dec_lock =0 indicates that the entire field of reactive power reduction is not locked.

[0080] 3-2) By analyzing the current terminal voltage U of each wind turbine gen_i The determination is made to ascertain the reactive power adjustment of a single wind turbine unit, and the target reactive power adjustment value for a single wind turbine unit under the current over-limit terminal voltage condition is calculated; where:

[0081] 3-2-1) If there exists a wind turbine i that satisfies U gen_i >U gen_max_i Then let Q gen_set_i =Q gen_i -Q gen_step_i ;

[0082] Let Q inc_lock =1 indicates that reactive power increase is blocked across the entire wind turbine field, meaning that reactive power adjustment is not allowed for any wind turbines on the field; let Q gen_inc_i =0, in kVar, means that the reactive power increase of wind turbine i is 0kVar, that is, wind turbine i is not allowed to increase reactive power.

[0083] 3-2-2) If there exists a wind turbine i that satisfies U gen_i <U gen_min_i Then let Q gen_set_i =Q gen_i +Q gen_step_i ;

[0084] Let Q dec_lock =1, where 1 indicates a full-site reactive power reduction lockout, meaning that no reactive power reduction adjustment is allowed for any wind turbine units on the site; Q gen_dec_i =0, in kVar, means that the reactive power reduction of wind turbine i is 0kVar, that is, wind turbine i is not allowed to reduce reactive power.

[0085] 3-2-3) If there exists a wind turbine i that satisfies U gen_max_warn_i ≤U gen_i ≤U gen_max_i Then let Q gen_inc_i =0.

[0086] 3-2-4) If there exists a wind turbine i that satisfies U gen_min_i ≤U gen_i ≤U gen_min_warn_i Then let Q gen_dec_i =0.

[0087] 3-2-5) If there exists a wind turbine i that satisfies U gen_min_warn_i <U gen_i <U gen_max_warn_i Then let the reactive power limit of wind turbine i be Q. gen_max_i for:

[0088]

[0089] Then according to Q gen_max_i Make a judgment:

[0090] If Q gen_max_i >Q gen_i Then let Q gen_inc_i =Q gen_max_i -Q gen_i ;

[0091] If Q gen_max_i ≤Q gen_i Then let Q gen_inc_i =0;

[0092] If Q gen_i >(-1)*Q gen_max_i Then let Q gen_dec_i =Q gen_i +Q gen_max_i ;

[0093] If Q gen_i ≤(-1)*Q gen_max_i Then let Q gen_dec_i =0.

[0094] 3-3) Repeat step 3-2) for the current terminal voltage U of all wind turbine units. gen_i After the determination is completed, proceed to step 4).

[0095] 4) Based on the results of step 3), by determining whether the low-voltage bus voltage of the wind farm exceeds the limit, update the reactive power adjustment of each wind turbine and calculate the reactive power adjustment target value for each wind turbine; the specific steps are as follows:

[0096] 4-1) Determine whether the low-voltage bus voltage of the wind farm exceeds the limit, where:

[0097] 4-1-1) If U low_bus >U low_bus_max And Q dec_lock =0, then the low-voltage bus voltage of the wind farm exceeds the upper limit;

[0098] Let Q inc_lock =1, proceed to step 4-2).

[0099] It should be noted that this step requires Q dec_lock =0, meaning that step 4-2 can only be executed if there is no overall reactive power reduction interlock in step 3). If there is an overall reactive power reduction interlock in step 3), then Q = 0. dec_lock =1, then the condition is not met and step 4-2 cannot be executed. That is, when the terminal voltage of a single wind turbine exceeds the lower limit and the low-voltage bus voltage of the wind farm exceeds the upper limit, the method described in this embodiment prioritizes ensuring that the terminal voltage of a single wind turbine is qualified.

[0100] 4-1-2) If U low_bus <U low_bus_min And Q inc_lock =0, then the low-voltage bus voltage of the wind farm exceeds the lower limit;

[0101] Let Q dec_lock =1, proceed to step 4-3).

[0102] It should be noted that this step requires Q inc_lock =0, indicating that step 4-3) can only be executed if the overall reactive power increase interlock does not occur in step 3). If the overall reactive power increase interlock occurs in step 3), i.e., Q inc_lock =1, then the condition is not met and step 4-3 cannot be executed. That is, when the terminal voltage of a single wind turbine exceeds the upper limit and the low-voltage bus voltage of the wind farm exceeds the lower limit, the method described in this embodiment prioritizes ensuring that the terminal voltage of a single wind turbine is qualified.

[0103] 4-1-3) If the judgment conditions in steps 4-1-1) and 4-1-2) are not met, proceed to step 5).

[0104] 4-2) Increase the reactive power of each wind turbine by Q. gen_inc_i =0, based on the current terminal voltage of each wind turbine, determine the reactive power regulation target value for each wind turbine, where:

[0105] If U gen_i >U gen_max_1st_i Then let Q gen_set_i =Q gen_i -Q gen_step_i ;

[0106] If U gen_max_2nd_i ≤Ugen_i ≤U gen_max_1st_i Then let Q gen_set_i =Q gen_i -Q gen_step_i / 2;

[0107] If U gen_i <U genmax_2nd_i Then let Q gen_set_i =Q gen_i ;

[0108] Then proceed to step 5).

[0109] 4-3) Reduce the reactive power of each wind turbine by Q. gen_dec_i =0, based on the current terminal voltage of each wind turbine, determine the reactive power regulation target value for each wind turbine, where:

[0110] If U gen_i <U gen_min_1st_i Then let Q gen_set_i =Q gen_i +Q gen_step_i ;

[0111] If U gen_min_1st_i ≤U gen_i ≤U gen_min_2nd_i Then let Q gen_set_i =Q gen_i +Q gen_step_i / 2;

[0112] If U gen_i >U gen_min_2nd_i Then let Q gen_set_i =Q gen_i ;

[0113] Then proceed to step 5).

[0114] 5) Based on the results of step 4), by determining whether the bus voltage at the wind farm's grid connection point exceeds the limit, calculate the reactive power regulation target value for each wind turbine; the specific steps are as follows:

[0115] 5-1) Calculate the upper and lower limits of the acceptable bus voltage at the grid connection point.

[0116] Among them, the upper limit of the qualified bus voltage at the grid connection point is denoted as U. high_bus_max_set The lower limit of the qualified bus voltage at the grid connection point is denoted as U. high_bus_min_set ;

[0117] U high_bus_max_set =U high_bus_set +U high_bus_dead

[0118] U high_bus_min_set =U high_bus_set -U high_bus_dead

[0119] Then determine:

[0120] If U high_bus_max_set >U high_bus_max Then let U high_bus_max_set =U high_bus_max ;

[0121] If U high_bus_min_set <U high_bus_min Then let U high_bus_min_set =U high_bus_min .

[0122] 5-2) Based on the results of step 5-1), determine whether the bus voltage at the wind farm's grid connection point exceeds the limit, where:

[0123] 5-2-1) If U high_bus >U high_bus_max_set And Q dec_lock =0, then the bus voltage at the grid connection point exceeds the upper limit, and then proceed to step 5-3);

[0124] 5-2-2) If U high_bus <U high_bus_min_set And Q inc_lock If the voltage of the grid connection point bus is 0, then the voltage of the grid connection point bus falls below the lower limit, and then proceed to step 5-4);

[0125] 5-2-3) If the judgment conditions in steps 5-2-1) and 5-2-2) are not met, proceed to step 6).

[0126] 5-3) Determine the reactive power regulation target value for each wind turbine, where:

[0127] If U gen_i >U gen_max_1st_i Then let Q gen_set_i =Q gen_i -Q gen_step_i ;

[0128] If U gen_max_2nd_i ≤U gen_i ≤U gen_max_1st_i Then let Q gen_set_i =Q gen_i -Q gen_step_i / 2;

[0129] If U gen_i <U genmax_2nd_i Then let Q gen_set_i =Q gen_i ;

[0130] Then proceed to step 6).

[0131] 5-4) Determine the reactive power regulation target value for each wind turbine, where:

[0132] If U gen_i <U gen_min_1st_i Then let Q gen_set_i =Q gen_i +Q gen_step_i ;

[0133] If U gen_min_1st_i ≤U gen_i ≤U gen_min_2nd_i Then let Q gen_set_i =Q gen_i +Q gen_step_i / 2;

[0134] If U gen_i >U gen_min_2nd_i Then let Q gen_set_i =Q gen_i ;

[0135] Then proceed to step 6).

[0136] 6) Calculate the total adjustable reactive power of the wind farm, where:

[0137] If Q inc_lock =1, then Q inc_all =0.

[0138] If Q inc_lock =0, then:

[0139]

[0140] If Q dec_lock =1, then Q dec_all =0.

[0141] If Q dec_lock =0, then:

[0142]

[0143] 7) The reactive power regulation target value of the wind turbine is sent to the wind turbine monitoring system for execution to achieve the control effect of this regulation cycle. The total adjustable reactive power of the wind farm is sent to the upper-level dispatch reactive power and voltage control master station. The master station uses the total adjustable reactive power of the wind farm as a constraint condition to participate in the next round of network-wide reactive power optimization calculation, and then calculates the new round of target value of the bus voltage at the wind farm grid connection point.

[0144] In a specific embodiment of the present invention, the reactive power and voltage control information of the wind farm interacting with the upper-level dispatch reactive power and voltage control master station is shown in Table 1 below:

[0145] Table 1. Reactive power and voltage control information of a wind farm according to a specific embodiment of the present invention.

[0146]

[0147]

[0148] In this embodiment, the wind farm reactive power and voltage control system periodically calculates four telemetry and teleindication values: the overall reactive power increase, the overall reactive power decrease, the overall reactive power increase blocking signal, and the overall reactive power decrease blocking signal. These values ​​are then sent to the upper-level reactive power and voltage control master station according to the table definition. The master station uses these four telemetry and teleindication values ​​as constraints in the next round of network-wide reactive power optimization calculations. This results in the calculation of the new target value for the wind farm's grid connection point bus voltage, which is then sent to the wind farm reactive power and voltage control system according to the table definition.

Claims

1. A wind farm reactive power control method considering individual wind turbine terminal voltage, characterized in that, The method comprises: At the arrival of each regulation cycle, according to the current terminal voltage of each wind turbine of the wind farm, determining the single-machine reactive power adjustment amount of each wind turbine, and calculating the reactive power regulation target value of the wind turbine in the case of the current terminal voltage exceeding the limit; When the low-voltage bus voltage of the wind farm exceeds the upper limit and the overall reactive power reduction is not blocked, or when the low-voltage bus voltage of the wind farm exceeds the lower limit and the overall reactive power increase is not blocked, updating the single-machine reactive power adjustment amount of each wind turbine, and calculating the reactive power regulation target value of each wind turbine; When the grid connection point bus voltage of the wind farm exceeds the upper limit and the overall reactive power reduction is not blocked, or when the grid connection point bus voltage of the wind farm exceeds the lower limit and the overall reactive power increase is not blocked, updating the reactive power regulation target value of each wind turbine; Based on the single-machine reactive power adjustment amount of each wind turbine, calculating the total reactive power adjustable amount of the wind farm to realize the reactive power control of the wind farm; The method further comprises: 1) initialize the full field reactive up regulation lockout signal Q inc_lock = 0, indicating that the full field reactive up regulation is not locked out; initialize the full field reactive down regulation lockout signal Q dec_lock = 0, indicating that the full field reactive down regulation is not locked out; 2) By determining the current terminal voltage of each wind turbine, determining the single-machine reactive power adjustment amount of the wind turbine, and calculating the reactive power regulation target value of the single wind turbine in the case of the current terminal voltage exceeding the limit; wherein: 2-1) If there exists a wind turbine i that satisfies U gen_i > U gen_max_i , then let Q gen_set_i = Q gen_i - Q gen_step_i ; Let Q inc_lock = 1, indicating that the full field reactive power up-regulation is locked; let the single-machine reactive power up-regulation amount Q gen_inc_i = 0 of the wind turbine i; wherein the subscript i represents the wind turbine serial number, U gen_i is the current terminal voltage of the wind turbine i, U gen_max_i is the upper limit of the terminal voltage of the wind turbine i, Q gen_set_i is the single-machine reactive power regulation target value of the wind turbine i, Q gen_step_i is the single-machine reactive power regulation step of the wind turbine i, Q gen_i is the single-machine reactive power of the wind turbine i; 2-2) If there exists a wind turbine i that satisfies U gen_i <U gen_min_i , then let Q gen_set_i = Q gen_i + Q gen_step_i ; Let Q dec_lock = 1, indicating full-field reactive power down-regulation lockout; let the individual reactive power down-regulation amount Q gen_dec_i = 0 for the wind turbine i; wherein U gen_min_i is the lower limit of the terminal voltage of the wind turbine i; 2-3) If there exists a wind turbine i satisfying U gen_max_warn_i ≤ U gen_i ≤ U gen_max_i , let Q gen_inc_i = 0; where U gen_max_warn_i is the upper limit of the machine terminal voltage warning of wind turbine i. 2-4) If wind turbine i meets U gen_min_i ≤ U gen_i ≤ U gen_min_warn_i , let Q gen_dec_i = 0; where U gen_min_warn_i is the lower limit of wind turbine i's terminal voltage warning. 2-5) If there exists wind turbine i satisfying U gen_min_warn_i <U gen_i <U gen_max_warn_i , then let the single-machine reactive power limit Q gen_max_i of wind turbine i be: where P gen_i is the single-machine active power of wind turbine i, COS gen_i is the single-machine power factor limit of wind turbine i; Then, according to Q gen_max_i A decision is made: If Q gen_max_i > Q gen_i , then let Q gen_inc_i = Q gen_max_i - Q gen_i ; If Q gen_max_i ≤ Q gen_i , then let Q gen_inc_i = 0; If Q gen_i > (-1) * Q gen_max_i , then let Q gen_dec_i = Q gen_i + Q gen_max_i ; If Q gen_i ≤ (-1) * Q gen_max_i , then let Q gen_dec_i = 0.

2. The method of claim 1, wherein, The method further comprises: If U low_bus > U low_bus_max and Q dec_lock = 0, the wind farm low-voltage bus voltage exceeds the upper limit, Q inc_lock = 1, and the single-machine reactive power up-regulation amount Q gen_inc_i = 0 of each wind turbine is determined according to the current terminal voltage of each wind turbine, and the reactive power regulation target value of each wind turbine is determined. If U gen_i > U gen_max_1st_i , then let Q gen_set_i = Q gen_i - Q gen_step_i ; If U gen_max_2nd_i ≤ U gen_i ≤ U gen_max_1st_i , then let Q gen_set_i = Q gen_i - Q gen_step_i / 2; If U gen_i < U genmax_2nd_i , then let Q gen_set_i = Q gen_i ; wherein U low_bus is the wind farm low voltage bus voltage, U low_bus_max is the wind farm low voltage bus voltage upper limit, U gen_max_1st_i is the wind turbine i terminal primary regulation voltage upper limit, U gen_max_2nd_i is the wind turbine i terminal secondary regulation voltage upper limit.

3. The method of claim 2, wherein, The method further comprises: If U low_bus < U low_bus_min and Q inc_lock = 0, the wind farm low voltage bus voltage is lower than the lower limit, Q dec_lock = 1, and the single-machine reactive down-regulation amount Q gen_dec_i = 0 of each wind turbine is determined according to the current terminal voltage of each wind turbine, and the reactive regulation target value of each wind turbine is determined. If U gen_i < U gen_min_1st_i , then let Q gen_set_i = Q gen_i + Q gen_step_i ; If U gen_min_1st_i ≤ U gen_i ≤ U gen_min_2nd_i , then let Q gen_set_i = Q gen_i + Q gen_step_i / 2; If U gen_i > U gen_min_2nd_i , then let Q gen_set_i = Q gen_i ; wherein, U low_bus_min is the low voltage limit of the wind farm low voltage bus, U gen_min_1st_i is the low voltage limit of the wind turbine i terminal primary regulation, U gen_min_2nd_i is the low voltage limit of the wind turbine i terminal secondary regulation.

4. The method of claim 3, wherein, The method further comprises: The grid-connected point bus voltage qualified upper limit U high_bus_max_set = U high_bus_set + U high_bus_dead ; The grid-connected point bus voltage qualified lower limit U high_bus_min_set = U high_bus_set - U high_bus_dead ; wherein U high_bus_set is the wind farm point of common coupling bus voltage target value, U high_bus_dead is the control dead band; Then determine: If U high_bus_max_set > U high_bus_max , then let U high_bus_max_set = U high_bus_max ; If U high_bus_min_set < U high_bus_min , then let U high_bus_min_set = U high_bus_min ; wherein U high_bus_max is the upper limit of the bus voltage at the point of interconnection of the wind farm, U high_bus_min is the lower limit of the bus voltage at the point of interconnection of the wind farm.

5. The method of claim 4, wherein, The method further comprises: If the grid-connected point bus voltage U high_bus > U high_bus_max_set and Q dec_lock = 0, the grid-connected point bus voltage exceeds the upper limit, and the reactive power regulation target value of each wind turbine is determined, wherein: If U gen_i > U gen_max_1st_i , then let Q gen_set_i = Q gen_i - Q gen_step_i ; If U gen_max_2nd_i ≤ U gen_i ≤ U gen_max_1st_i , then let Q gen_set_i = Q gen_i - Q gen_step_i / 2; If U gen_i < U genmax_2nd_i then let Q gen_set_i = Q gen_i .

6. The method of claim 5, wherein, The method further comprises: If the grid-connected point bus voltage U high_bus <U high_bus_min_set and Q inc_lock = 0, the grid-connected point bus voltage is lower than the lower limit, and the reactive power regulation target value of each wind turbine is determined, wherein: If U gen_i < U gen_min_1st_i , then let Q gen_set_i = Q gen_i + Q gen_step_i ; If U gen_min_1st_i ≤ U gen_i ≤ U gen_min_2nd_i , then let Q gen_set_i = Q gen_i + Q gen_step_i / 2; If U gen_i > U gen_min_2nd_i , then let Q gen_set_i = Q gen_i .

7. The method of claim 6, wherein, The method further comprises: The calculation of the total reactive power adjustable amount of the wind farm comprises: If Q inc_lock = 1, then Q inc_all = 0; If Q inc_lock = 0, then: If Q dec_lock = 1, then Q dec_all = 0; If Q dec_lock = 0, then: Wherein, N is the total number of wind turbines; Q inc_all is the total field reactive power up-regulation amount, Q dec_all is the total field reactive power down-regulation amount.

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