Optimal power distribution factor calculation method for automatic power generation control

Abstract

The invention discloses an optimal power distribution factor calculation method for automatic power generation control, and the method comprises the steps: bringing power distribution factors of a renewable energy power generation station and a synchronous generator set into a power grid frequency response model, and obtaining a relation between the frequency deviation of a regional power grid and the power distribution factors; calculating a frequency control performance index of the automatic power generation control system: taking the obtained frequency control performance index of the automatic power generation control system as a target function, taking the power distribution factor of each power generation unit as an optimization variable, and obtaining an optimization model of the power distribution factor of the automatic power generation control system; and solving the optimization model by adopting an intelligent optimization algorithm to obtain the optimal power distribution factor of the automatic power generation control system. According to the method, the dynamic frequency response characteristic of the power grid is considered, and the optimal power distribution factor can be solved, so that the frequency response characteristic of the power grid and the control performance of an automatic power generation control system are better improved, and the frequency stability of the power grid is better enhanced.

Description

Technical Field

[0001] The present invention relates to a method for calculating an optimal power allocation factor for automatic power generation control, which is applicable to an automatic power generation control system of an interconnected power grid containing n regions. The optimal power allocation factor can improve the frequency stability level when a power disturbance occurs in the power grid. In addition, the optimal power allocation factor can improve the control performance of the automatic power generation control system. Background Art

[0002] As my country continues to promote the construction of new power systems, the installed capacity of renewable energy such as wind power and photovoltaics is increasing. After a high proportion of renewable energy power stations are connected to the power grid, the equivalent inertia level of the power system continues to decrease. The randomness, volatility and intermittency of the active power output of renewable energy power stations will bring severe challenges to the frequency safety and stability of the power system. Problems such as insufficient frequency support capacity, lack of frequency regulation resources and high risk of frequency instability in power systems with a high proportion of renewable energy continue to emerge. Therefore, the participation of renewable energy power stations such as wind power and photovoltaics in automatic power generation control is an effective way to improve the frequency safety and stability of the power grid. At present, the relevant research carried out by scholars at home and abroad mainly focuses on the participation of renewable energy power stations in automatic power generation control of the power grid, such as the following published literature:

[0003] [1]KLER D,KUMARV,RANAK P S.Optimal Integral Minus ProportionalDerivative Controller Design by EvolutionaryAlgorithm for Thermal-RenewableEnergy-Hybrid Power Systems[J].IET Renewable Power Generation, 2019,13(11):2000-2012.

[0004] [2] Wang Haowei, Qu Wenfei, Wan Yongan, et al. Multi-source automatic power generation control system and operation optimization based on model predictive control [J]. Hydropower and New Energy, 2023, 37(09): 20-23.

[0005] Reference [1] studied the application of integral negative proportional differential controller in automatic power generation control system containing synchronous generators and renewable energy power generation stations, and used genetic algorithm to adjust the parameters of integral negative proportional differential controller. The research results show that the integral negative proportional differential controller performs better than proportional integral controller and proportional integral differential controller in terms of maximum frequency deviation, frequency setting time and frequency ripple. Reference [2] proposed an operation optimization strategy for multi-source automatic power generation control system based on model predictive control, designed a power distributor based on particle swarm algorithm, reduced the amount of wind abandoned in wind power stations and the amount of light abandoned in photovoltaic power stations, and improved the dynamic control performance of automatic power generation control system. However, the above-mentioned references did not consider the dynamic frequency response characteristics of the power grid when studying the automatic power generation control strategy containing renewable energy power generation stations and synchronous generators. Therefore, it is of great practical significance to combine the frequency control performance index and intelligent optimization algorithm of the automatic power generation control system to study the calculation method of the optimal power allocation factor of the automatic power generation control system, so as to enhance the frequency stability of the power grid. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to propose a method for calculating the optimal power allocation factor of automatic power generation control. The method comprehensively considers the frequency control performance indicators of the automatic power generation control system, and proposes an optimization model for the power allocation factor of the automatic power generation control system of an interconnected power grid containing n regions. The optimal power allocation factor can be obtained, thereby better enhancing the frequency stability of the power grid.

[0007] The technical solution of the present invention is achieved in this way:

[0008] A method for calculating an optimal power allocation factor for automatic power generation control, the specific steps are as follows:

[0009] A1) The power allocation factors of renewable energy power plants and synchronous generators are introduced into the grid frequency response model, and the relationship between the regional grid frequency deviation and the power allocation factor is obtained as follows:

[0010]

[0011] Where Δf i , D i and M i are the frequency deviation, damping coefficient and inertia time constant of the power grid in region i; ΔP ci is the active power shortage of the power grid in region i; ΔP di is the disturbance power deviation of the power grid in region i; T ij Represents the tie line synchronization coefficient; G th , G hy , G wt , G pvare the coefficients of thermal power units, hydropower units, wind farms and photovoltaic plants respectively; α thi , α hyi , α wti and α pvi are the power allocation factors of thermal power units, hydropower units, wind farms and photovoltaic farms in the regional i power grid; R thi is the speed regulation coefficient of the thermal power unit in the power grid in region i; d th is the primary frequency regulation dead zone of the thermal power unit; R hyi is the regulation coefficient of the hydropower unit speed regulator in the power grid in region i; d hy is the primary frequency regulation dead zone of the hydropower unit; H WTi is the virtual inertia control coefficient of the wind farm station in the regional i power grid; K WTi is the droop control coefficient of the wind farm station in the regional i power grid; d wt is the primary frequency regulation dead zone of the wind farm station; H PVi is the virtual inertia control coefficient of the photovoltaic station in the regional i power grid; K PVi is the droop control coefficient of the photovoltaic station in the regional i power grid; d pv It is the primary frequency regulation dead zone of the photovoltaic station;

[0012] A2) Calculate the frequency control performance index of the automatic power generation control system according to the following formula:

[0013]

[0014] Where J i is the frequency control performance index of the automatic power generation control system of the regional i power grid; sp is the number of sampling points; Δf i (t) is the frequency deviation of the power grid in region i at time t; f N is the rated frequency of the power grid; f i,max and f i,min are the maximum and minimum values ​​of the frequency of the power grid in region i, respectively; ε is a constant coefficient. When the power grid in region i has an active power shortage, causing the frequency of the power grid in region i to drop, ε=1; when the power grid in region i has an active power surplus, causing the frequency of the power grid in region i to rise, ε=0;

[0015] A3) The frequency control performance index of the automatic power generation control system obtained in step A2) is used as the objective function, and the power allocation factor of each power generation unit in the automatic power generation control system is used as the optimization variable; the optimization model of the power allocation factor of the automatic power generation control system of the interconnected power grid containing n regions is obtained according to the following formula:

[0016]

[0017] An intelligent optimization algorithm is used to solve the optimization model of the power allocation factor of the automatic power generation control system, that is, the optimal power allocation factor of the automatic power generation control system is obtained.

[0018] Furthermore, in the process of solving the optimization model of the power allocation factor of the automatic power generation control system given in step A3), the following constraints must also be met:

[0019] Constraints 1) The power allocation factors of thermal power units, hydropower units, wind farms and photovoltaic farms in the regional i power grid are used as optimization variables and need to meet the value range constraints. The specific expressions are as follows:

[0020]

[0021] At the same time, the sum of the power allocation factors of each power source in the area i power grid is 1, and the power allocation factor of each power source in the area i power grid should also meet the following constraints:

[0022] α thi +α hyi +α wti +α pvi =1

[0023] Constraint 2) The synchronous generator set and renewable energy power station also need to meet the ramp rate limit constraint and active output limit constraint. The specific expressions are as follows:

[0024]

[0025] Where ΔP ri (t) is the change in active power of synchronous generators and renewable energy power stations in the power grid of region i at time t; R lim P is the 1-minute regulation rate limit of synchronous generators and renewable energy power stations in the power grid of region i; ri,N is the rated installed capacity of synchronous generators and renewable energy power stations in the power grid of region i; ΔP ri,max is the maximum adjustable capacity of synchronous generators and renewable energy power stations in the power grid of region i; P ri (t) is the active power of synchronous generators and renewable energy power stations in the power grid of region i at time t;

[0026] Constraint 3) The tie line exchange power also needs to meet the maximum and minimum exchange power constraints. The specific expression is as follows:

[0027] P tiei,min ≤P tiei (t)≤P tiei,max

[0028] Where P tiei,max and Ptiei,min are the maximum and minimum values ​​of the interconnection line exchange power allowed by the power grid in region i; P tiei (t) is the interconnection line exchange power of the power grid in region i at time t;

[0029] Constraint 4) The active output of the synchronous generator set and the renewable energy power station must also meet the output active power balance constraint. The specific expression is as follows:

[0030] P rthi (t)+P rhyi (t)+P wti (t)+P pvi (t)-P tiei (t)-P di (t) = 0

[0031] Where P rthi (t) is the active power of the thermal power unit in the regional i power grid at time t, P rhyi (t) is the active power of the hydropower unit in the regional i power grid at time t, P wti (t) is the active power of the wind farm in the power grid of region i at time t, P pvi (t) is the active power of the photovoltaic station in the regional i power grid at time t, P tiei (t) is the interconnection line exchange power of the power grid in region i at time t, P di (t) is the disturbance power of the power grid in region i at time t.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention takes into account the dynamic frequency response characteristics of the power grid, provides an optimization model for the power allocation factor of the automatic power generation control system of an interconnected power grid containing n regions, explains the various constraints that need to be met in the process of solving the optimization model, and can quickly solve the optimal power allocation factor through an intelligent optimization algorithm, thereby better improving the frequency response characteristics of the power grid and the control performance of the automatic power generation control system, and better enhancing the frequency stability of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the frequency response waveform of the power grid in area 1 when a random load power disturbance occurs in the power grid.

[0035] Figure 2 This is the frequency response waveform of the power grid in area 2 when a random load power disturbance occurs in the power grid. DETAILED DESCRIPTION

[0036] The specific implementation modes of the present invention are described in detail below with reference to the accompanying drawings.

[0037] The present invention is used to calculate the optimal power allocation factor of an automatic power generation control system. During a load power disturbance in a power grid, the power allocation factor is used as an optimization variable to calculate the frequency control performance index of the automatic power generation control system, and then the objective function value is calculated based on the power allocation factor optimization model of the automatic power generation control system. Finally, under the condition of meeting various constraints, the objective function value is minimized by an intelligent optimization algorithm to obtain the optimal power allocation factor of the automatic power generation control system.

[0038] The specific implementation steps of the present invention are as follows:

[0039] A method for calculating an optimal power allocation factor for automatic power generation control is used to optimize the allocation of regional regulation demand instructions for a multi-region interconnected power grid during a period when the power grid frequency deviates from the rated frequency. The specific steps are as follows:

[0040] A1) The power allocation factors of renewable energy power plants and synchronous generators are introduced into the grid frequency response model, and the relationship between the regional grid frequency deviation and the power allocation factor is obtained as follows:

[0041]

[0042] Where Δf i , D i and M i are the frequency deviation, damping coefficient and inertia time constant of the power grid in region i; ΔP ci is the active power shortage of the power grid in region i; ΔP di is the disturbance power deviation of the power grid in region i; T ij Represents the tie line synchronization coefficient; G th , G hy , G wt , G pv are the coefficients of thermal power units, hydropower units, wind farms and photovoltaic plants respectively; α thi , α hyi , α wti and α pvi are the power allocation factors of thermal power units, hydropower units, wind farms and photovoltaic farms in the regional i power grid; R thi is the speed regulation coefficient of the thermal power unit in the power grid in region i; d th is the primary frequency regulation dead zone of the thermal power unit; R hyi is the regulation coefficient of the hydropower unit speed regulator in the power grid in region i; d hy is the primary frequency regulation dead zone of the hydropower unit; H WTi is the virtual inertia control coefficient of the wind farm station in the regional i power grid; K WTi is the droop control coefficient of the wind farm station in the regional i power grid; d wt is the primary frequency regulation dead zone of the wind farm station; HPVi is the virtual inertia control coefficient of the photovoltaic station in the regional i power grid; K PVi is the droop control coefficient of the photovoltaic station in the regional i power grid; d pv It is the primary frequency regulation dead zone of the photovoltaic station;

[0043] A2) Calculate the frequency control performance index of the automatic power generation control system according to the following formula:

[0044]

[0045] Where J i is the frequency control performance index of the automatic generation control system of the regional power grid i; J i The first term is the RMS value of the frequency deviation of the power grid in region i; sp is the number of sampling points; Δf i (t) is the frequency deviation of the power grid in region i at time t; f N is the rated frequency of the power grid; J i The second term is the overshoot of the frequency response of the power grid in region i; i,max and f i,min are the maximum and minimum values ​​of the frequency of the power grid in region i, respectively; ε is a constant coefficient. When the power grid in region i has an active power shortage, causing the frequency of the power grid in region i to drop, ε=1; when the power grid in region i has an active power surplus, causing the frequency of the power grid in region i to rise, ε=0;

[0046] A3) The frequency control performance index of the automatic power generation control system obtained in step A2) is used as the objective function, and the power allocation factor of each power generation unit in the automatic power generation control system is used as the optimization variable; the optimization model of the power allocation factor of the automatic power generation control system of the interconnected power grid containing n regions is obtained according to the following formula:

[0047]

[0048] An intelligent optimization algorithm is used to solve the optimization model of the power allocation factor of the automatic power generation control system, that is, the optimal power allocation factor of the automatic power generation control system is obtained.

[0049] In the process of solving the optimization model of the power allocation factor of the automatic power generation control system given in step A3), the following constraints must also be met:

[0050] Constraints 1) The power allocation factors of thermal power units, hydropower units, wind farms and photovoltaic farms in the regional i power grid are used as optimization variables and need to meet the value range constraints. The specific expressions are as follows:

[0051]

[0052] At the same time, the sum of the power allocation factors of each power source in the regional i power grid is 1, and the power allocation factor of each power source in the regional i power grid should also meet the following constraints:

[0053] α thi +α hyi +α wti +α pvi =1

[0054] Constraint 2) The synchronous generator set and renewable energy power station also need to meet the ramp rate limit constraint and active output limit constraint. The specific expressions are as follows:

[0055]

[0056] Where ΔP ri (t) is the change in active power of synchronous generators and renewable energy power stations in the power grid of region i at time t; R lim P is the 1-minute regulation rate limit of synchronous generators and renewable energy power stations in the power grid of region i; ri,N is the rated installed capacity of synchronous generators and renewable energy power stations in the power grid of region i; ΔP ri,max is the maximum adjustable capacity of synchronous generators and renewable energy power stations in the regional i power grid; P ri (t) is the active power of synchronous generators and renewable energy power stations in the power grid of region i at time t;

[0057] Constraint 3) The tie line exchange power also needs to meet the maximum and minimum exchange power constraints. The specific expression is as follows:

[0058] P tiei,min ≤P tiei (t)≤P tiei,max

[0059] Where P tiei,max and P tiei,min are the maximum and minimum values ​​of the interconnection line exchange power allowed by the power grid in region i; P tiei (t) is the interconnection line exchange power of the power grid in region i at time t;

[0060] Constraint 4) The active output of the synchronous generator set and the renewable energy power station must also meet the output active power balance constraint. The specific expression is as follows:

[0061] P rthi (t)+P rhyi (t)+P wti (t)+P pvi (t)-P tiei (t)-P di (t) = 0

[0062] Where P rthi (t) is the active power of the thermal power unit in the regional i power grid at time t, P rhyi (t) is the active power of the hydropower unit in the regional i power grid at time t, P wti (t) is the active power of the wind farm in the power grid of region i at time t, P pvi (t) is the active power of the photovoltaic station in the regional i power grid at time t, P tiei (t) is the interconnection line exchange power of the power grid in region i at time t, P di (t) is the disturbance power of the power grid in region i at time t.

[0063] Under the above four constraints, the intelligent optimization algorithm is applied to solve the automatic power generation control system power allocation factor optimization model given in step A3), and the optimal power allocation factor of the automatic power generation control system can be obtained.

[0064] Effect description of the present invention:

[0065] Figure 1 The frequency response waveform of the power grid in region 1 is given when a random load power disturbance occurs in the power grid. During the frequency fluctuation of the power grid in region 1, the method for calculating the optimal power allocation factor of the automatic power generation control system proposed in the present invention is used. According to the calculation results of the frequency response waveform of the power grid in region 1, it can be seen that the maximum frequency deviation of the power grid in region 1 is 0.0748Hz, and the frequency of the power grid in region 1 does not exceed the reasonable operating range. The effectiveness of the method proposed in the present invention has been verified.

[0066] Figure 2 The frequency response waveform of the power grid in region 2 is given when a random load power disturbance occurs in the power grid. During the frequency fluctuation of the power grid in region 2, the method for calculating the optimal power allocation factor of the automatic power generation control system proposed in the present invention is adopted. According to the calculation results of the frequency response waveform of the power grid in region 2, it can be seen that the maximum frequency deviation of the power grid in region 2 is 0.0481Hz, and the frequency of the power grid in region 2 does not exceed the reasonable operating range. The effectiveness of the method proposed in the present invention has been verified.

[0067] It can be seen that the optimal power allocation factor calculation method for automatic power generation control proposed in the present invention can enhance the frequency stability of the power grid and improve the control performance of the automatic power generation control system.

[0068] Finally, it should be noted that the above examples of the present invention are merely examples for illustrating the present invention, and are not intended to limit the embodiments of the present invention. Although the applicant has described the present invention in detail with reference to the preferred embodiments, for those of ordinary skill in the art, other different forms of changes and modifications can be made based on the above description. It is impossible to list all the embodiments here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for calculating the optimal power allocation factor for automatic power generation control, characterized in that: The specific steps are as follows: A1) The power allocation factors of renewable energy power plants and synchronous generators are introduced into the grid frequency response model, and the relationship between the regional grid frequency deviation and the power allocation factor is obtained as follows: Where Δf i , D i and M i are the frequency deviation, damping coefficient and inertia time constant of the power grid in region i; ΔP ci is the active power shortage of the power grid in region i; ΔP di is the disturbance power deviation of the power grid in region i; T ij Represents the tie line synchronization coefficient; G th , G hy , G wt , G pv are the coefficients of thermal power units, hydropower units, wind farms and photovoltaic plants respectively; α thi , α hyi , α wti and α pvi are the power allocation factors of thermal power units, hydropower units, wind farms and photovoltaic farms in the regional i power grid; R thi is the speed regulation coefficient of the thermal power unit in the power grid in region i; d th is the primary frequency regulation dead zone of the thermal power unit; R hyi is the regulation coefficient of the hydropower unit speed regulator in the power grid in region i; d hy is the primary frequency regulation dead zone of the hydropower unit; H WTi is the virtual inertia control coefficient of the wind farm station in the regional i power grid; K WTi is the droop control coefficient of the wind farm station in the regional i power grid; d wt is the primary frequency regulation dead zone of the wind farm station; H PVi is the virtual inertia control coefficient of the photovoltaic station in the regional i power grid; K PVi is the droop control coefficient of the photovoltaic station in the regional i power grid; d pv It is the primary frequency regulation dead zone of the photovoltaic station; A2) Calculate the frequency control performance index of the automatic power generation control system according to the following formula: Where J i is the frequency control performance index of the automatic power generation control system of the regional i power grid; sp is the number of sampling points; Δf i (t) is the frequency deviation of the power grid in region i at time t; f N is the rated frequency of the power grid; f i,max and f i,min are the maximum and minimum values ​​of the power grid frequency in region i, respectively; ε is a constant coefficient. When the power grid in region i has an active power shortage, which causes the frequency of the power grid in region i to drop, ε=1; when the power grid in region i has an active power surplus, which causes the frequency of the power grid in region i to rise, ε=0; A3) The frequency control performance index of the automatic power generation control system obtained in step A2) is used as the objective function, and the power allocation factor of each power generation unit in the automatic power generation control system is used as the optimization variable; the optimization model of the power allocation factor of the automatic power generation control system of the interconnected power grid containing n regions is obtained according to the following formula: An intelligent optimization algorithm is used to solve the optimization model of the power allocation factor of the automatic power generation control system, that is, the optimal power allocation factor of the automatic power generation control system is obtained.

2. The method for calculating the optimal power allocation factor for automatic power generation control according to claim 1, characterized in that: In the process of solving the optimization model of the power allocation factor of the automatic power generation control system given in step A3), the following constraints must also be met: Constraints 1) The power allocation factors of thermal power units, hydropower units, wind farms and photovoltaic farms in the regional i power grid are used as optimization variables and need to meet the value range constraints. The specific expressions are as follows: At the same time, the sum of the power allocation factors of each power source in the regional i power grid is 1, and the power allocation factor of each power source in the regional i power grid should also meet the following constraints: α thi +α hyi +α wti +α pvi ＝1 Constraint 2) The synchronous generator set and renewable energy power station also need to meet the ramp rate limit constraint and active output limit constraint. The specific expressions are as follows: Where ΔP ri (t) is the change in active power of synchronous generators and renewable energy power stations in the power grid of region i at time t; R lim P is the 1-minute regulation rate limit of synchronous generators and renewable energy power stations in the power grid of region i; ri,N is the rated installed capacity of synchronous generators and renewable energy power stations in the power grid of region i; ΔP ri,max is the maximum adjustable capacity of synchronous generators and renewable energy power stations in the regional i power grid; P ri (t) is the active power of synchronous generators and renewable energy power stations in the power grid of region i at time t; Constraint 3) The tie line exchange power also needs to meet the maximum and minimum exchange power constraints. The specific expression is as follows: P tiei,min ≤P tiei (t)≤P tiei,max Where P tiei,max and P tiei,min are the maximum and minimum values ​​of the interconnection line exchange power allowed by the power grid in region i; P tiei (t) is the interconnection line exchange power of the power grid in region i at time t; Constraint 4) The active output of the synchronous generator set and the renewable energy power station must also meet the output active power balance constraint. The specific expression is as follows: P rthi (t)+P rhyi (t)+P wti (t)+P pvi (t)-P tiei (t)-P di (t)=0 Where P rthi (t) is the active power of the thermal power unit in the regional i power grid at time t, P rhyi (t) is the active power of the hydropower unit in the regional i power grid at time t, P wti (t) is the active power of the wind farm in the power grid of region i at time t, P pvi (t) is the active power of the photovoltaic station in the regional i power grid at time t, P tiei (t) is the interconnection line exchange power of the power grid in region i at time t, P di (t) is the disturbance power of the power grid in region i at time t.

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