A method and system for reactive power coordination control and circulation suppression in a wind-solar-storage storage station cluster

Abstract

This invention provides a method and system for reactive power coordination control and circulating current suppression in a wind, solar, and energy storage power plant cluster, belonging to the field of power system operation control technology. The method includes: collecting operating data from each substation and calculating a normalized circulating current index; activating a circulating current suppression mode when the index exceeds limits, obtaining the total reactive power target command for the power plant cluster, and identifying the target reactive power direction based on a dead zone threshold; dynamically clamping the upper or lower limits of reactive power output of each substation according to the target direction, generating a unidirectional blocking command to cut off the circulating current loop; and performing margin balancing control in non-suppression mode. This invention eliminates the influence of power plant capacity differences on the criteria through a normalized index, effectively solves the reactive power circulating current and control deadlock problems caused by opposite output by utilizing dynamic clamping logic based on target commands, and integrates voltage safety verification to achieve coordinated optimization of reactive power resources across multiple power plants and stable control of grid voltage.

Description

Technical Field

[0001] This invention relates to the field of power system operation control and automation technology, and in particular to a method and system for reactive power coordination control and circulating current suppression applied to new energy power plant clusters including wind power plants, photovoltaic power plants, and energy storage power plants. Background Technology

[0002] With the continuous expansion of new energy installed capacity, the proportion of power station clusters composed of wind power, photovoltaic, and energy storage power stations in the power grid is increasing. In actual operation, each power station is usually equipped with an independent automatic voltage control (AVC) system, which only uses the voltage or power factor at its grid connection point as the control target. Due to the lack of unified top-level coordination, the control strategies, response speeds, and regulation dead zones of different power stations vary, making it easy for them to operate independently.

[0003] In existing technologies, situations often arise where the reactive power output polarity is opposite between power stations: some stations generate inductive reactive power, while others generate capacitive reactive power. Although the total reactive power may meet dispatch requirements from the grid connection point (e.g., the sum is zero), a huge reactive power circulation actually forms within the power station group. This reactive power circulation not only wastes reactive power resources and causes equipment losses, increasing network losses, but may also cause some units to reach their output limits prematurely, reducing the overall voltage support capacity of the power station group. Furthermore, traditional circulating current suppression methods often rely on measured feedback values ​​for adjustment, which can easily fall into logic deadlock or oscillation when the total output is close to zero or a dead zone; and for heterogeneous power stations with large capacity differences, there is a lack of a unified quantitative circulating current assessment standard, leading to difficulties in parameter configuration and a large workload for on-site commissioning.

[0004] Therefore, there is an urgent need to provide a reactive power coordination control method and system that can uniformly quantify the degree of circulating current, accurately identify the target direction, and actively block the circulating current loop, so as to achieve coordinated operation and voltage stability among multiple substations. Summary of the Invention

[0005] The purpose of this invention is to address the problems of severe reactive power circulation between power stations, uneven resource allocation, and control deadlock oscillations existing in the prior art, by providing a method and system for coordinated reactive power control and circulation suppression of wind, solar, and energy storage power station clusters. This invention achieves precise quantification and active suppression of circulation by constructing a normalized circulation index and a multi-level coordinated control architecture, ensuring the unidirectional and balanced reactive power output of the power station cluster.

[0006] To solve the above-mentioned technical problems, the technical solution adopted in this invention is a method for reactive power coordination control and circulation suppression of wind, solar and energy storage station clusters, comprising the following steps: S1. Circulation index calculation: Collect real-time operation data of grid connection points of each substation in the power station group, and calculate the normalized circulation index based on the actual reactive power generated by each substation. S2, Mode switching judgment: Compare the circulation level index in S1 with the preset start threshold. When the index exceeds the start threshold, activate the circulation suppression mode. S3, Direction Recognition: In the circulating current suppression mode in S2, the total reactive power target command of the power station group is obtained, and the total reactive power target command is compared with the preset dead zone threshold to determine the target reactive power direction. S4. Dynamic clamping execution: Based on the target reactive power direction in S3, perform dynamic clamping operation on the upper or lower limit of reactive power output of each substation, generate a one-way blocking command to block reactive power output opposite to the target reactive power direction, and send the command to each substation.

[0007] In the preferred scheme, the normalized circulation degree index in step S1 The calculation formula is shown in equation (1): (1) in, For the number of substations, For the first The actual reactive power output of each substation For the first The upper limit of reactive power output of each substation; if the denominator is zero, the circulation degree index is set to 0. This is the magnification factor.

[0008] In the preferred embodiment, step S2 further includes exit logic: setting an exit threshold. and exit delay time ,in When the real-time monitoring shows that the circulation level index is lower than the exit threshold and the duration of this state exceeds the exit delay time, the circulation suppression mode is exited and the system switches to the margin balance control mode.

[0009] In the preferred embodiment, step S4 specifically includes: if the total reactive power target command is greater than the positive dead zone threshold, the target reactive power direction is determined to be capacitive, and the lower limit of reactive power output of all substations is forcibly clamped to zero, allowing the substations to output capacitive reactive power and prohibiting the output of inductive reactive power; if the total reactive power target command is less than the negative dead zone threshold, the target reactive power direction is determined to be inductive, and the upper limit of reactive power output of all substations is forcibly clamped to zero, allowing the substations to output inductive reactive power and prohibiting the output of capacitive reactive power; if the total reactive power target command is between the positive dead zone threshold and the negative dead zone threshold, the target reactive power direction is determined to be in a dead zone zero state, and the upper and lower limits of reactive power output of all substations are forcibly clamped to zero.

[0010] In the preferred embodiment, when switching to the margin balance control mode, the adjustment steps include: calculating the upward and downward margin percentages of each substation, and calculating the average margin of the substation group; and weighting the total reactive power target command according to the deviation between the margin percentage of each substation and the average margin, generating reactive power allocation commands for each substation, so that the reactive power load rate of each substation tends to be consistent.

[0011] In the preferred scheme, the margin percentage is increased. The calculation formula is shown in equation (2), which is the percentage reduction margin. The calculation formula is shown in equation (3): (2) (3) in, For the first The lower limit of the reactive power output of a substation.

[0012] In the preferred embodiment, the method further includes a voltage safety priority verification step: real-time monitoring of the bus voltage at the grid connection point of the substation group; if the bus voltage exceeds the limit, immediately blocking the circulating current suppression logic and any margin balancing logic in steps S2 to S4, and prioritizing the generation of an emergency voltage support command and sending it to each substation.

[0013] This invention also provides a reactive power coordination control and circulating current suppression system for wind, solar and energy storage station clusters, applied to the above-described method, comprising: The data acquisition module is used to collect real-time operating data from each substation within the station group; The index calculation module is used to perform the calculation of the normalized circulation degree index; The multi-level coordinated control strategy module contains a circulating current suppression and dead zone discrimination unit. In the circulating current suppression mode, the circulating current suppression and dead zone discrimination unit determines the target direction according to the total reactive power target command of the power station group and outputs clamping signals for the upper or lower limit of reactive power output of each substation.

[0014] In the preferred embodiment, the multi-level coordinated control strategy module adopts a signal flow serial processing architecture, including three cascaded control units: The first-level voltage safety arbitration unit, deployed at the end of the control logic, has the highest priority and is used to cut off the upper-level signal and output a voltage support command when the voltage exceeds the limit. The second-level circulating current suppression and dead zone discrimination unit is deployed in the middle layer as a dynamic amplitude limiting filter. When the circulating current suppression mode is activated, it applies a one-way clamping constraint to the input control command according to the target direction. The third-level margin balancing allocation unit, deployed at the base layer, is used to generate basic reactive power allocation instructions in non-circulating current suppression mode.

[0015] In the preferred embodiment, the second-level circulating current suppression and dead zone discrimination unit has a built-in dead zone comparator. The dead zone comparator is configured to: trigger bidirectional zeroing logic when the absolute value of the total reactive power target command is less than the preset dead zone threshold, and simultaneously set the upper limit signal and lower limit signal of reactive power output to all substations to zero.

[0016] This invention introduces a normalized circulating current severity index, enabling a unified quantitative assessment of the severity of circulating current in heterogeneous power plant clusters. This eliminates the impact of capacity differences between different power plants and solves the problem of traditional methods struggling to establish universal criteria. The invention employs direction recognition and dynamic clamping logic based on total reactive power target commands, physically blocking output paths opposite to the target direction. This effectively eliminates control deadlock and oscillations near dead zones, completely eliminating reactive power circulating current. Furthermore, this invention constructs a multi-level coordinated control architecture that includes voltage safety arbitration, circulating current suppression clamping, and margin balancing allocation. This architecture can achieve balanced allocation of reactive power resources under normal operating conditions and prioritize voltage safety and circulating current suppression under abnormal operating conditions, significantly improving the operating efficiency of power plant clusters and grid stability. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a flowchart illustrating the method of the present invention; Figure 2 This is a schematic diagram of the system architecture of the present invention. Detailed Implementation

[0018] Example 1 like Figure 1 As shown, a method for reactive power coordination control and circulating current suppression in a wind, solar, and energy storage cluster operates in the AVC system of the host computer coordination control station of the cluster. It collects data from each substation in real time, calculates the circulating current level index, and issues coordination commands. The method includes the following steps: S1. Data Acquisition and Preprocessing: The system periodically collects real-time operational data from N grid-connected points in the wind, solar, and energy storage power station group via the power dispatch data network or the station's internal communication bus. The collected data includes: The actual reactive power generated at the grid connection point of the i-th power station ; The maximum reactive power output of the i-th power station ; Lower limit of reactive power output of the i-th power station ; Real-time value of bus voltage .

[0019] S2. Circulating Current Existence Determination: The system determines whether circulating reactive current exists based on the collected actual reactive power generation values. The determination logic is as follows: iterate through all power stations... If at least one power station has a positive actual reactive power value, and at the same time another power station has a negative actual reactive power value, then it is determined that there is a reactive power circulation in the system.

[0020] S3. Calculate the circulation severity quantification index. To accurately assess the severity of the circulation and use it as a basis for subsequent control, this embodiment uses a normalized calculation formula to quantify the circulation severity index. The calculation formula is shown in equation (1): (1) When all power stations output power in the same direction, this value is 0; the greater the difference in direction, the larger the numerator, representing the total amount of reactive power ineffectively exchanged. The denominator is normalized to eliminate the influence of capacity differences between different power stations on the indicator. When the denominator is zero, the indicator is set to 0 by default, and the control logic is locked. The coefficient K is used to amplify the indicator to a numerical range that is easy to observe and set. The denominator term normalizes the numerator term, and its significant technical significance lies in realizing the standardization and dimensionlessness of the control threshold. Regardless of the scale of the power stations, maintenance personnel only need to set a unified dimensionless threshold to adapt to all types of power stations. This greatly reduces the difficulty of parameter configuration and on-site debugging workload of multi-power station collaborative control systems, and solves the technical problem of difficulty in setting universal criteria in heterogeneous power station groups using traditional methods.

[0021] S4. Calculate reactive power margin and degree of imbalance. While calculating the circulating current, the system calculates the reactive power adjustment margin of each station to prevent individual stations from reaching their output limits prematurely.

[0022] The formula for calculating the single-station margin and the percentage increase in margin is shown in equation (2): (2) The formula for calculating the percentage reduction margin is shown in equation (3): (3) The formulas for calculating the group average margin are shown in equations (4) and (5): (4) (5) S5. Control strategy generation and mode switching: The system generates control strategies based on the calculated circulation level index. and the received total reactive power target command of the system It automatically switches between circulating current suppression mode and margin balance control mode, and generates the final control command. Specifically, it includes the following steps: S501, Activation and Exit Criteria for Circulation Suppression Mode, Setting the Circulation Initiation Threshold and exit threshold And set an exit delay time. This is to prevent the system from oscillating frequently near the critical point. The real-time calculated circulation index... When the circulation level index is reached, the system immediately enters circulation suppression mode; when the circulation level index is reached... And the duration of this state exceeds When this happens, the system exits the circulating current suppression mode and switches back to the margin balance control mode.

[0023] S502, Circulating Current Suppression Execution Logic: When the system is in circulating current suppression mode, in order to eliminate outward power output, the system first obtains the current total reactive power target instruction for the power station group. And compare it with the preset anti-vibration dead zone threshold. The comparison is performed, and the following logic is executed in three modes: Capacitive inhibition mode: if The overall system requirement is determined to be capacitive. At this point, the system issues a one-way blocking command to all substations within the power station cluster, forcing all substations to lower their reactive power output limits. Clamp to 0. This allows substations with positive output to continue outputting power, but forces substations with negative output to revert to 0, thereby cutting off the circulating current loop.

[0024] Emotional inhibition mode: If The overall system demand is determined to be inductive. At this point, the system forcibly increases the reactive power output limit of all substations. Clamp to 0. This allows substations with negative output to continue outputting power, but forces substations with positive output to revert to 0.

[0025] Dead Zone Zeroing Mode: If The system's overall demand is determined to be in the dead zone or close to zero. At this point, to prevent directional ambiguity under small targets from causing persistent circulating currents, the system executes a forced zeroing strategy: simultaneously clamping the upper and lower limits of reactive power output of all substations to 0, or setting the reactive power target value of all substations to 0. At this time, all substations are forced to stop reactive power output, quickly eliminating internal circulating currents caused by inconsistent directions, pending the circulating current severity index... After the temperature drops and the S501 exit condition is met, normal adjustment will resume.

[0026] S503, Marginal Equalization Control: When the system is in non-circulating current suppression mode, a margin equalization control strategy is adopted to maximize the overall regulation capacity of the power station group and prevent individual power stations from overloading. The system uses the deviation between the upward / downward adjustment margin percentage of each substation calculated in S4 and the group's average margin to set the total reactive power target command. Weighted allocation is performed. The allocation principle is: stations with larger margins undertake more reactive power regulation tasks, so that the reactive power load rate of each substation tends to be consistent, thereby reducing the risk of circulating current caused by opposite output polarity at the source.

[0027] S6. Safety Interlocking and Command Issuance: Before issuing the command, a voltage safety check is performed to determine the bus voltage. If the voltage exceeds the limit, all coordination logic is immediately locked, and strong voltage support is executed. To prevent AGC step commands from causing power surges and thus voltage spikes, the system calculates the rate of change of reactive power commands generated for each substation. If the rate of change exceeds a preset ramp threshold, the command is smoothed to transition to the target value via a ramp. The verified and smoothed control commands are then sent to the local AVC of each substation for execution.

[0028] Example 2 like Figure 2 As shown, this embodiment provides a control system capable of implementing the above method. This system is typically deployed in the regional control center or coordination control master station of a new energy power plant cluster, and communicates bidirectionally with each substation via industrial Ethernet or power dispatch data network.

[0029] The system mainly consists of the following three core modules: Data Acquisition and Time Synchronization Module: This module is equipped with a communication interface and a clock synchronization module, used to connect to each grid-connected substation within the power station group. It collects in real time the actual reactive power generation, upper and lower limits of reactive power output, equipment status, and bus voltage of each substation's grid connection point.

[0030] Indicator Calculation Module: This unit is the core of the system's computation, and it contains two key calculation sub-units: The normalized circulation calculation unit introduces normalization processing logic, making the calculated circulation level index a dimensionless value independent of the facility size. This eliminates the need for maintenance personnel to calculate thresholds separately for facility groups with different capacities; they only need to set unified standardized criteria, greatly reducing system configuration complexity and the risk of malfunction.

[0031] The margin real-time assessment unit is used to calculate the upward and downward margins of each substation in real time, and to calculate the average margin of the station group, providing data support for subsequent equilibrium control.

[0032] Multi-level Coordination and Control Strategy Module: This unit is the decision-making center of this system. It adopts a signal flow serial processing and three-level priority arbitration architecture, specifically containing the following three cascaded control units: The first level, the voltage safety arbitration unit, is deployed at the very end of the control logic. It monitors the bus voltage in real time. When the voltage exceeds the limit, this unit activates the signal blocking / overriding logic, directly cutting off the output channels of the subsequent circulating current suppression and margin balancing modules, and forcibly generating a strong voltage support command to ensure that grid safety is the highest constraint.

[0033] The second level, the circulating current suppression and dead zone discrimination unit, is deployed after the margin allocation unit. This unit has built-in direction recognition logic and a dynamic clamper. When it receives the total reactive power target command... At this time, the target direction is first determined by a comparator. If determined to be a capacitive requirement, the unit dynamically modifies the lower limit constraint of the output signal to 0, thereby physically blocking any negative instructions that the margin allocation unit may generate; if If determined to be an emotional demand, the unit dynamically modifies the upper limit constraint of the output signal to 0; if If this happens, both the upper and lower bounds will be set to zero. This unit only... It intervenes in the signal flow when necessary, otherwise it is in a bypass state and does not perform any processing on the signal.

[0034] The third level, the margin balancing allocation module, is responsible for generating basic reactive power allocation instructions. When the system does not trigger voltage over-limit and the circulating current indicators are normal, this unit acts as the main control logic, weighting and allocating the total target instructions according to the margin deviation to generate the initial substation control instructions.

[0035] In summary, the system described in Embodiment 2 fully implements the method described in Embodiment 1 at the system architecture level through the collaborative work of the data acquisition module, the index calculation module, and the multi-level coordinated control strategy module. This system utilizes a three-layer cascaded architecture of voltage safety arbitration, circulating current suppression and dead zone identification, and margin balancing allocation to achieve comprehensive control from the underlying voltage safety to the underlying resource optimization. In particular, through the second-level dynamic clamping logic, it can proactively cut off reverse power output according to grid target instructions. Combined with the third-level margin balancing strategy, it eliminates circulating current while achieving refined management of reactive power resources, significantly improving the grid-connected power quality and operational economy of the new energy power plant cluster.

Claims

1. A method for reactive power coordination control and circulation suppression in a wind-solar-storage storage station cluster, characterized in that, Includes the following steps: S1. Circulation index calculation: Collect real-time operation data of grid connection points of each substation in the power station group, and calculate the normalized circulation index based on the actual reactive power generated by each substation. S2, Mode switching judgment: Compare the circulation level index in S1 with the preset start threshold. When the index exceeds the start threshold, activate the circulation suppression mode. S3, Direction Recognition: In the circulating current suppression mode in S2, the total reactive power target command of the power station group is obtained, and the total reactive power target command is compared with the preset dead zone threshold to determine the target reactive power direction. S4. Dynamic clamping execution: Based on the target reactive power direction in S3, perform dynamic clamping operation on the upper or lower limit of reactive power output of each substation, generate a one-way blocking command to block reactive power output opposite to the target reactive power direction, and send the command to each substation.

2. The method for reactive power coordination control and circulation suppression of a wind-solar-storage storage station group according to claim 1, characterized in that, Normalized circulation degree index in step S1 The calculation formula is shown in equation (1): (1); in, For the number of substations, For the first The actual reactive power output of each substation For the first The upper limit of reactive power output of each substation; if the denominator is zero, the circulation degree index is set to 0. This is the magnification factor.

3. The method for reactive power coordination control and circulation suppression of a wind-solar-storage storage station group according to claim 1, characterized in that, Step S2 also includes exit logic: Set exit threshold and exit delay time ,in ; When the real-time monitoring shows that the circulation level index is lower than the exit threshold and the duration of this state exceeds the exit delay time, the circulation suppression mode is exited and the system switches to the margin balance control mode.

4. The method for reactive power coordination control and circulation suppression of a wind-solar-storage storage station group according to claim 1, characterized in that, Step S4 specifically includes: If the total reactive power target command is greater than the positive dead zone threshold, the target reactive power direction is determined to be capacitive, and the lower limit of reactive power output of all substations is forcibly clamped to zero, allowing the substations to output capacitive reactive power and prohibiting the output of inductive reactive power. If the total reactive power target instruction is less than the negative dead zone threshold, the target reactive power direction is determined to be inductive, and the reactive power output limit of all substations is forcibly clamped to zero, allowing the substations to output inductive reactive power and prohibiting the output of capacitive reactive power. If the total reactive power target instruction is between the positive dead zone threshold and the negative dead zone threshold, the target reactive power direction is determined to be in a dead zone zero state, and at the same time, the upper limit and lower limit of reactive power output of all substations are clamped to zero.

5. The method for reactive power coordination control and circulation suppression of a wind-solar-storage storage station group according to claim 3, characterized in that, When switching to the margin balance control mode, the adjustment steps include: Calculate the percentage increase and decrease of the margin for each substation, and calculate the average margin for the station group. Based on the deviation between the margin percentage of each substation and the average margin, the total reactive power target instruction is weighted and allocated to generate reactive power allocation instructions for each substation, so that the reactive power load rate of each substation tends to be consistent.

6. The method for reactive power coordination control and circulation suppression of a wind-solar-storage storage station group according to claim 5, characterized in that, Increase margin percentage The calculation formula is shown in equation (2), which is the percentage reduction margin. The calculation formula is shown in equation (3): (2); (3); in, For the first The lower limit of the reactive power output of a substation.

7. The method for reactive power coordination control and circulation suppression of a wind-solar-storage storage station group according to claim 1, characterized in that, The method also includes a voltage safety priority verification step: Real-time monitoring of bus voltage at grid connection points of power station clusters; If the bus voltage exceeds the limit, immediately block the circulating current suppression logic in steps S2 to S4 and any margin balancing logic, and prioritize generating an emergency voltage support command and sending it to each substation.

8. A reactive power coordination control and circulation suppression system for a wind-solar-storage storage station cluster, characterized in that, include: The data acquisition module is used to collect real-time operating data from each substation within the station group; The index calculation module is used to perform the calculation of the normalized circulation degree index as described in claim 2; A multi-level coordinated control strategy module is configured to execute the method described in claim 1. It includes a circulating current suppression and dead zone discrimination unit. In the circulating current suppression mode, the circulating current suppression and dead zone discrimination unit determines the target direction according to the total reactive power target command of the power station group and outputs a clamping signal for the upper or lower limit of reactive power output of each substation.

9. A reactive power coordination control and circulating current suppression system for a wind-solar-storage power station cluster according to claim 8, characterized in that, The multi-level coordinated control strategy module adopts a signal flow serial processing architecture, including three cascaded control units: The first-level voltage safety arbitration unit, deployed at the end of the control logic, has the highest priority and is used to cut off the upper-level signal and output a voltage support command when the voltage exceeds the limit. The second-level circulating current suppression and dead zone discrimination unit is deployed in the middle layer as a dynamic amplitude limiting filter. When the circulating current suppression mode is activated, it applies a one-way clamping constraint to the input control command according to the target direction. The third-level margin balancing allocation unit, deployed at the base layer, is used to generate basic reactive power allocation instructions in non-circulating current suppression mode.

10. A reactive power coordination control and circulating current suppression system for a wind-solar-storage storage station group according to claim 9, characterized in that, The second-level circulating current suppression and dead zone discrimination unit has a built-in dead zone comparator. The dead zone comparator is configured to trigger bidirectional zeroing logic when the absolute value of the total reactive power target command is less than the preset dead zone threshold, and at the same time set the upper limit signal and lower limit signal of reactive power output to all substations to zero.

Images