A power grid reactive power compensation capacity optimization method meeting multiple operation modes

Abstract

The application discloses a power grid reactive power compensation capacity optimization method meeting multiple operation modes and relates to the power grid operation and maintenance field. Different power operation modes are needed for relative regulation and control according to different operation modes. The application comprises the following steps: reading typical section real-time data and operation equipment models and equipment parameters of multiple operation modes; establishing power grid operation constraints corresponding to the multiple operation modes; establishing an objective function; establishing multiple sets of optimization models for the constraint inequalities and optimization objectives under the multiple operation modes and jointly solving the multiple sets of optimization models; if the optimized base state power flow converges, directly outputting a configuration result; otherwise, outputting the nearest optimization result; and optimizing the power grid reactive power compensation capacity according to the output reactive power compensation capacity configuration scheme. The technical scheme realizes reactive power compensation capacity optimization calculation based on multiple objectives and meeting multiple operation modes, and meets reactive power voltage regulation requirements under various extreme load conditions.

Description

Technical Field

[0001] This invention relates to the field of power grid operation and maintenance, and in particular to a method for optimizing the reactive power compensation capacity of a power grid to meet multiple operating modes. Background Technology

[0002] The Zhejiang power grid has formed an ultra-high voltage power grid structure of "two AC and two DC". The overall electrical connection of the East China power grid is closer, and the stability characteristics of the power grid have changed significantly. The Zhejiang power grid will exhibit obvious characteristics of a multi-feed ultra-high voltage AC and DC hybrid receiving-end power grid.

[0003] Voltage is a crucial indicator of power quality, and grid loss is a vital economic indicator for grid operation. To ensure voltage quality for users, it is necessary to optimize and analyze reactive power and voltage operation modes. Main transformer tap changes are an important means of voltage regulation in the power grid. While the tap positions of on-load tap changers can be controlled in real-time by AVC (Automatic Voltage Control), most 500kV main transformers and some 220kV main transformers in the Zhejiang power grid are off-load tap changers. Adjusting the tap positions of off-load tap changers must be performed while the main transformer is de-energized. In actual grid operation, it is difficult to schedule power outages for 500kV and 220kV main transformers; tap adjustments can only be scheduled during low-load periods such as the Spring Festival. After adjustment, the tap positions need to adapt to various grid operation modes throughout the year. Therefore, this paper proposes an optimization scheme to address the issue of off-load tap changer tap position planning, aiming to achieve a more reasonable voltage distribution across the transformers. This is of great significance for ensuring grid voltage quality and improving voltage qualification rates.

[0004] Power operation varies during weekdays, weekends, summer peak seasons, and the Spring Festival, necessitating corresponding adjustments to ensure safe and stable power supply. For example, during the Spring Festival, China's most unique holiday, the Zhejiang power grid experiences significant reactive power excess and excessive voltage. During this period, the load is extremely low, while the charging power flowing into the grid is high. Inductive compensation equipment is insufficient, necessitating the shutdown of 500kV and 220kV lines to reduce charging power and allowing generating units to operate at leading voltage levels to absorb reactive power. However, line shutdowns and leading voltage operation reduce grid reliability and stability. Simultaneously, it is necessary to pre-determine regional power factor control targets. Reactive power and voltage operation mode simulation calculations are required, aiming to eliminate voltage exceedances, to determine reactive power and voltage control measures during the Spring Festival. This will ensure the AVC system operates normally during the Spring Festival, reducing the workload of control personnel and guaranteeing voltage compliance rates. Summary of the Invention

[0005] The technical problem to be solved and the technical task proposed by this invention is to improve and refine existing technical solutions, and to provide a power grid reactive power compensation capacity optimization method that meets multiple operating modes, for providing regulation strategies including those during the Spring Festival, in order to improve the voltage qualification rate during the Spring Festival and other periods. To this end, this invention adopts the following technical solution.

[0006] A method for optimizing the reactive power compensation capacity of a power grid that satisfies multiple operating modes includes the following steps:

[0007] 1) Read real-time data of typical cross-sections under various operating modes, including weekday, weekend, summer peak, and Spring Festival modes; to support typical operating modes including weekday, weekend, summer peak, and Spring Festival modes;

[0008] 2) Read the operating equipment model and equipment parameters of the power grid; and assume that the equipment model and equipment parameters of the power grid are the same under all operating modes;

[0009] 3) Based on the equipment model and real-time data from multiple sections, establish power grid operation constraints corresponding to various operating modes; power grid operation constraints include node power flow balance constraints, node voltage constraints, transformer tap constraints, and capacitor state constraints.

[0010] 4) Establish the objective function, which includes the reactive power compensation capacity cost, node voltage over-limit penalty, and system network loss cost;

[0011] 5) Establish multiple optimization models for node balancing under various operating modes, constraint inequalities under each mode, and optimization objectives, and solve them jointly;

[0012] 6) Based on the calculation results, perform optimization. If the optimized ground state power flow converges, output the configuration result directly; otherwise, indicate that it has not converged and output the most recent optimization result; thus obtaining a reactive power compensation capacity configuration scheme based on multiple objectives and satisfying multiple operating modes.

[0013] 7) Optimize the reactive power compensation capacity of the power grid based on the output reactive power compensation capacity configuration scheme.

[0014] Since the operating equipment of the power grid is usually kept stable, it can be assumed that the equipment model and equipment parameters of the power grid are the same under all operating modes, so only one set of model and parameters is needed.

[0015] As a preferred technical means: In step 5), considering the safety constraints of power grid operation under various operating modes, a nonlinear programming optimization problem is established with the comprehensive optimization objectives of minimizing the cost of reactive power compensation capacity, minimizing node voltage overruns, and minimizing system network losses, and the problem is solved jointly to obtain the optimization results of the reactive power compensation capacity of the power grid.

[0016] As a preferred technical approach: taking the safety of power grid operation under various operating modes as a constraint, and considering multiple optimization objectives including the cost of reactive power compensation capacity, its expression is:

[0017]

[0018] st

[0019]

[0020] In the formula, w r Cost per unit capacity of reactor; w c The unit capacity cost of the reactive power compensator; R i The required reactor capacity for node i; C i The required reactive power compensator capacity for node i; S slack This represents the set of balancing machines; the sum of the outputs of these balancing machines actually corresponds to network losses. and C j These represent the operating states of compensator j before and after optimization, respectively, with 0 indicating exit and 1 indicating operation. Cj The adjustment cost of compensator j is represented by the state before compensator optimization. Since the values ​​are known, the optimization problem can be solved by... Determined W Cj symbol; and t k W represents the tap position before and after optimization of the on-load tap changer k. Tk This indicates the weight of the tap adjustment. Before optimization calculation, the desired adjustment direction of the tap needs to be selected in advance based on the current reactive power and voltage operating state of the power grid, and then W is determined. Tk The symbol is . The superscript 'k' indicates the operation mode number, and SK is the operation mode set; and These represent the voltage amplitude, voltage phase, active power injection, reactive power injection, active load, and reactive load of node i under operating mode k, respectively. The parallel susceptance of compensation node i under operating mode k; The per-unit transformation ratio of transformer on-load tap i under operating mode k; SN is the set of all topology points; SG is the set of all generator terminal topology points; SC is the set of parallel compensation devices; ST is the set of transformer on-load taps.

[0021] As a preferred technical means: In step 4), based on the unit capacity price of the capacitor, a formula for calculating the reactive power compensation capacity cost is established; based on the cost of system network loss, a formula for calculating network loss cost is established; based on the adjustment cost of the current discrete equipment, formulas for calculating the reactive power compensation cost and the transformer tap adjustment cost are calculated respectively. After obtaining the corresponding weights, a comprehensive multi-objective function that takes into account the above three factors is established.

[0022] Beneficial Effects: This technical solution addresses various power grid operating modes, especially special load operating modes including Spring Festival mode, weekdays, weekends, and peak periods. It uses the balance of power grid nodes and the safety and stability of voltage and reactive power under various operating modes as constraints, while also considering multiple optimization objectives such as minimizing the cost of reactive power compensation capacity configuration, maximizing the qualification rate of key power grid voltages, and minimizing network losses in reactive power at critical points to meet voltage and reactive power optimization requirements. This achieves optimized calculation of reactive power compensation capacity based on multiple objectives to satisfy various operating modes, meeting the reactive power and voltage regulation needs under various extreme load conditions. Attached Figure Description

[0023] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings.

[0025] like Figure 1 As shown, the present invention includes the following steps:

[0026] 1) Read real-time data of typical cross-sections under various operating modes, including weekday, weekend, summer peak, and Spring Festival modes; to support typical operating modes including weekday, weekend, summer peak, and Spring Festival modes;

[0027] 2) Read the operating equipment model and equipment parameters of the power grid; and assume that the equipment model and equipment parameters of the power grid are the same under all operating modes;

[0028] 3) Based on the equipment model and real-time data from multiple sections, establish power grid operation constraints corresponding to various operating modes; power grid operation constraints include node power flow balance constraints, node voltage constraints, transformer tap constraints, and capacitor state constraints.

[0029] 4) Establish the objective function, which includes the reactive power compensation capacity cost, node voltage over-limit penalty, and system network loss cost;

[0030] 5) Establish multiple optimization models for node balancing under various operating modes, constraint inequalities under each mode, and optimization objectives, and solve them jointly;

[0031] 6) If the optimization converges, output the configuration result directly; otherwise, indicate that it has not converged and output the most recent optimization result; thus obtaining a reactive power compensation capacity configuration scheme based on multiple objectives and satisfying multiple operating modes.

[0032] 7) Optimize the reactive power compensation capacity of the power grid based on the output reactive power compensation capacity configuration scheme.

[0033] Mathematical modeling was performed on real-time cross-sectional data of multiple typical power grid operating modes, including the Spring Festival mode, and the parameters of the power grid. At the same time, the safety constraints of power grid operation under each operating mode were considered. A nonlinear programming optimization problem was established with the comprehensive optimization objectives of minimizing reactive power compensation capacity cost, node voltage over-limit, and system network loss, and the problem was solved jointly to obtain the optimization results of reactive power compensation capacity of the power grid.

[0034] This method for optimizing reactive power compensation capacity to meet various extreme power grid operating conditions, such as the Spring Festival, uses the safety of power grid operation under each operating mode as a constraint and considers multiple optimization objectives, including the cost of reactive power compensation capacity. Mathematically, it can be described as the following multi-objective optimization problem:

[0035]

[0036] st

[0037]

[0038] In the formula, w r Cost per unit capacity of reactor; w c The unit capacity cost of the reactive power compensator; R i The required reactor capacity for node i; C i The required reactive power compensator capacity for node i; S slack This represents the set of balancing machines; the sum of the outputs of these balancing machines actually corresponds to network losses. and C j These represent the operating states of compensator j before and after optimization, respectively, with 0 indicating exit and 1 indicating operation. Cj The adjustment cost of compensator j is represented by the state before compensator optimization. Since the values ​​are known, the optimization problem can be solved by... Determined W Cj symbol; and t k W represents the tap position before and after optimization of the on-load tap changer k. Tk This indicates the weight of the tap adjustment. Before optimization calculation, the desired adjustment direction of the tap needs to be selected in advance based on the current reactive power and voltage operating state of the power grid, and then W is determined. Tk The symbol is . The superscript 'k' indicates the operation mode number, and SK is the operation mode set; and These represent the voltage amplitude, voltage phase, active power injection, reactive power injection, active load, and reactive load of node i under operating mode k, respectively. The parallel susceptance of compensation node i under operating mode k; The per-unit transformation ratio of transformer on-load tap i under operating mode k; SN is the set of all topology points; SG is the set of all generator terminal topology points; SC is the set of parallel compensation devices; ST is the set of transformer on-load taps.

[0039] above Figure 1 The proposed method for optimizing the reactive power compensation capacity of a power grid that satisfies multiple operating modes is a specific embodiment of the present invention. It embodies the substantial features and progress of the present invention. Based on the actual needs of use, equivalent modifications in shape, structure, etc., can be made to it according to the inspiration of the present invention, all of which are within the scope of protection of this solution.

Claims

1. A method for optimizing the reactive power compensation capacity of a power grid to meet multiple operating modes, characterized in that... Includes the following steps: 1) Read real-time data of typical cross-sections under various operating modes, including weekday, weekend, summer peak, and Spring Festival modes; to support typical operating modes including weekday, weekend, summer peak, and Spring Festival modes; 2) Read the operating equipment model and equipment parameters of the power grid; and assume that the equipment model and equipment parameters of the power grid are the same under all operating modes; 3) Based on the equipment model and real-time data from multiple sections, establish power grid operation constraints corresponding to various operating modes; power grid operation constraints include node power flow balance constraints, node voltage constraints, transformer tap constraints, and capacitor state constraints; 4) Establish the objective function, which includes the reactive power compensation capacity cost, node voltage over-limit penalty, and system network loss cost; 5) Establish multiple optimization models for node balancing under various operating modes, constraint inequalities under each mode, and optimization objectives, and solve them jointly; 6) Based on the calculation results, perform optimization. If the optimized ground state power flow converges, output the configuration result directly; otherwise, indicate that it has not converged and output the most recent optimization result; thus obtaining a reactive power compensation capacity configuration scheme based on multiple objectives and satisfying multiple operating modes. 7) Optimize the reactive power compensation capacity of the power grid based on the output reactive power compensation capacity configuration scheme; In step 5), considering the safety constraints of power grid operation under each operating mode, a nonlinear programming optimization problem is established with the comprehensive optimization objectives of minimizing reactive power compensation capacity cost, node voltage overrun, and system network loss, and then solved jointly to obtain the optimization results of the power grid's reactive power compensation capacity. Taking the safety of power grid operation under various operating modes as a constraint, and considering multiple optimization objectives including reactive power compensation capacity costs, its expression is: In the formula, Cost per unit capacity of reactor; Cost per unit capacity of reactive power compensator; The required reactor capacity for node i; The reactive power compensator capacity that needs to be configured for node i; This represents the set of balancing machines; the sum of the outputs of these balancing machines actually corresponds to network losses. and These represent compensators. j The running status before and after optimization, 0 indicates exit, 1 indicates running. Indicates compensator j The adjustment cost is expressed in the state before the compensator optimization. Since the values ​​are known, the optimization problem can be solved by... Definite symbol; and These represent on-load tap changing points. k Tap positions before and after optimization The weight of the tap adjustment is indicated. Before optimization calculation, the desired adjustment direction of the tap needs to be selected in advance based on the current reactive power and voltage operating state of the power grid, and then the adjustment direction needs to be determined. The symbol; the superscript k indicates the operation mode number, and SK is the operation mode set; , , , , and These represent the voltage amplitude, voltage phase, active power injection, reactive power injection, active load, and reactive load of node i under operating mode k, respectively. The parallel susceptance of compensation node i under operating mode k; The per-unit transformation ratio of on-load tap i of the transformer under operating mode k; It is the set of all topological points; The set of all terminal topology points; A collection of parallel compensation devices; This refers to the collection of on-load taps for transformers.

2. The method for optimizing the reactive power compensation capacity of a power grid that satisfies multiple operating modes according to claim 1, characterized in that: In step 4), a formula for calculating the reactive power compensation capacity cost is established based on the unit capacity price of the capacitor; a formula for calculating the network loss cost is established based on the system network loss cost. Based on the current adjustment costs of discrete equipment, the calculation formulas for reactive power compensation costs and transformer tap adjustment costs are calculated separately. After obtaining the corresponding weights, a comprehensive multi-objective function that takes into account the above three factors is established.

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