Power distribution method for automatic power generation control

Abstract

The invention discloses a power distribution method for automatic power generation control, and the method comprises the steps: calculating the standby capacity, which can be used for the secondary frequency modulation of an automatic power generation control system, of each power generation unit when the frequency fluctuation of a power grid is caused by the imbalance of active power; and calculating a power distribution factor of each power generation unit according to different regional adjustment powers and the spare capacity of each power generation unit. And after the power grid frequency returns to normal, calculating a power distribution factor according to the maximum adjustable capacity of each power generation unit. And multiplying the power distribution factor of each power generation unit by the region regulation power of the region where the power generation unit is located to obtain the power distribution of each power generation unit in the region. The dynamic updating method for the power distribution factor of the automatic power generation control system in the frequency change process can be given, and therefore the frequency stability level of a power grid is better improved.

Description

Technical Field

[0001] The present invention relates to a power distribution method for automatic power generation control, which is applicable to a power grid containing synchronous generator sets and renewable energy power generation stations. The method can accurately calculate the available frequency regulation capacity of the renewable energy power generation stations and the synchronous generator sets under different active power imbalance conditions of the power grid, and provide a dynamic update process of the power distribution factor of the automatic power generation control system during frequency change. Background Art

[0002] As the concept of environmental protection has a deeper and deeper impact on the whole society, vigorously developing renewable energy power generation technologies such as wind power, photovoltaics, and hydropower, and building a new power system that can safely and reliably replace renewable energy has become one of the important ways for my country's economic and social sustainable and healthy development. However, the large-scale access of wind power, photovoltaics and other renewable energy power stations to the power grid through power electronic equipment will lead to a continuous decrease in the equivalent inertia level of the power system and introduce a large number of random power disturbances to the power system. The power system will face severe challenges such as insufficient frequency support capacity, lack of frequency regulation resources and high risk of frequency instability. Therefore, it is urgent to incorporate renewable energy power stations into the existing frequency regulation control framework of the power grid and study the power allocation method for synchronous generators and renewable energy power stations to coordinate and participate in the automatic power generation control of the power grid. At present, the relevant research carried out by scholars at home and abroad mainly focuses on the automatic power generation control method of thermal power units and renewable energy power stations, such as the following published literature:

[0003] [1] Luo Ying. Automatic generation control of interconnected power system with wind and solar power generation[J]. Heilongjiang Electric Power, 2020, 42(02): 142-147+154.

[0004] [2]KARANAM AN,SHAW BA New Two-Degree ofFreedom Combined PIDController for Automatic Generation Control of a Wind IntegratedInterconnected Power System[J].Protection and Control ofModern Power Systems,2022,7(2):1-16.

[0005] Reference [1] established a frequency response model of a power grid consisting of a photovoltaic power generation system, a wind power generation system and a thermal power generation system, and designed a proportional integral differential controller based on the guided fireworks algorithm to adjust the thermal power output power and maintain the power balance of the power grid. However, this document did not include the photovoltaic power generation system and the wind power generation system in the automatic power generation control framework of the power grid. Reference [2] designed a new dual-degree-of-freedom combined proportional integral differential controller for automatic power generation control of a power grid containing a wind power cluster, and optimized the controller gain coefficient using the crow search algorithm to better suppress the fluctuation of the power grid frequency. However, none of the above documents considered the optimization and improvement of the power allocation method of automatic power generation control by utilizing the frequency response characteristics difference between renewable energy power generation stations and conventional synchronous generators. Therefore, it is of great practical significance to comprehensively consider the frequency response characteristics difference between thermal power units, hydropower units and renewable energy power generation stations, study the power allocation method of the automatic power generation control system during power grid frequency fluctuations, and thus improve the frequency stability level 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 power allocation method for automatic power generation control, which accurately calculates the available frequency regulation capacity of renewable energy power generation stations and synchronous generator sets under different active power imbalance conditions in the power grid, and gives a dynamic update process of the power allocation factor of the automatic power generation control system during frequency changes, thereby better improving the frequency stability level of the power grid.

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

[0008] A power distribution method for automatic power generation control, the specific steps are as follows:

[0009] A1) When active power imbalance causes grid frequency fluctuation, calculate the spare capacity of each generating unit that can be used for secondary frequency regulation of the automatic generation control system;

[0010] A2) Calculating the power allocation factor of each power generation unit according to the different regional adjustment powers and the spare capacity of each power generation unit;

[0011] A3) After the grid frequency returns to normal, the power allocation factor is calculated according to the maximum adjustable capacity of each generating unit;

[0012] A4) Multiplying the power allocation factor of each power generation unit by the regional regulation power of the area, the power allocation of each power generation unit in the area is obtained.

[0013] In the present invention, the power generation unit includes a thermal power unit, a hydropower unit, a wind power station and a photovoltaic station.

[0014] In step A1), the spare capacity of each power generation unit that can be used for secondary frequency regulation of the automatic power generation control system is calculated according to the fluctuation of the power grid frequency in the following two situations:

[0015] Scenario 1: When the grid frequency drops due to active power shortage, the spare capacity of each generating unit that can be used for secondary frequency regulation of the automatic power generation control system is calculated according to the following formula:

[0016]

[0017] Where P wt,avl It is the spare capacity of the wind farm station that can be used for secondary frequency regulation of the automatic power generation control system; P wt,N is the rated capacity of the wind farm; K WT is the droop control coefficient of the wind farm; Δf is the grid frequency deviation; d wt is the primary frequency regulation dead zone of the wind farm station; H WT is the virtual inertia control coefficient of the wind farm; P pv,avl It is the spare capacity of the photovoltaic station that can be used for secondary frequency regulation of the automatic power generation control system; P pv,N is the rated capacity of the photovoltaic station; K PV is the droop control coefficient of the photovoltaic station; d pv is the primary frequency regulation dead zone of the photovoltaic station; H PV is the virtual inertia control coefficient of the photovoltaic station; P th,avl It is the spare capacity of thermal power units that can be used for secondary frequency regulation of automatic power generation control system; P th,N is the rated capacity of the thermal power unit; R th is the adjustment coefficient of the thermal power unit speed governor; d th is the primary frequency regulation dead zone of the thermal power unit; P hy,avl It is the spare capacity of the hydropower unit that can be used for secondary frequency regulation of the automatic power generation control system; P hy,N is the rated capacity of the hydropower unit; R hy is the adjustment coefficient of the hydropower unit speed governor; d hy It is the primary frequency regulation dead zone of the hydropower unit;

[0018] Scenario 2: When the grid frequency rises due to active power surplus, the spare capacity of each generating unit that can be used for secondary frequency regulation of the automatic generation control system is calculated according to the following formula:

[0019]

[0020] Furthermore, in step A2), the power allocation factor of each power generation unit is calculated according to the following method for different regional power adjustment situations:

[0021] When the area adjusts the power P c Satisfy the conditions: 0<|Pc |≤|P wt,avl +P pv,avl |When When |P wt,avl +P pv,avl |<|P c |≤|P wt,avl +P pv,avl +P th,avl +P hy,avl |When When |P wt,avl +P pv,avl +P th,avl +P hy,avl |<|P c |When

[0022] Where α th , α hy , α wt and α pv They are the power allocation factors of thermal power units, hydropower units, wind farms and photovoltaic plants respectively.

[0023] Furthermore, in step A3), the power allocation factor of each power generation unit is calculated as follows:

[0024]

[0025] Where P th,max , P hy,max , P wt,max and P pv,max They are the maximum adjustable capacities of thermal power units, hydropower units, wind farms and photovoltaic plants respectively.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention can calculate the available frequency regulation capacity of renewable energy power generation stations and synchronous generator sets (i.e., the spare capacity that can be used for secondary frequency regulation of the automatic power generation control system) during the period of grid frequency fluctuation according to different grid active power imbalance conditions, and then calculate the power allocation factor of each power generation unit according to the regional adjustment power and the available frequency regulation capacity of each power generation unit. When the grid frequency is stable, the power allocation factor is calculated according to the maximum adjustable capacity of each power generation unit, and then a dynamic update method of the power allocation factor is obtained. The present invention also takes into account the available frequency regulation capacity of all power generation units in the system, so the calculated power allocation factor can better improve the frequency stability level of the grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the frequency response waveform of the power grid when the active load of the power grid suddenly increases.

[0029] Figure 2 This is the frequency response waveform of the power grid when the active load of the power grid suddenly decreases. DETAILED DESCRIPTION

[0030] The specific implementation modes of the present invention are described in detail below with reference to the accompanying drawings.

[0031] The present invention is used to calculate the power allocation factor of an automatic power generation control system during power grid frequency fluctuations. During the period when active power imbalance occurs in the power grid, the value of the power allocation factor can be obtained by calculating the available frequency regulation capacity of each power generation unit. When the power grid frequency is stable, the value of the power allocation factor is further obtained according to the maximum adjustable capacity of each power generation unit, thereby obtaining a dynamic update method for the power allocation factor of the automatic power generation control system.

[0032] The specific implementation steps of the present invention are as follows:

[0033] A1) When active power imbalance causes grid frequency fluctuation, calculate the spare capacity of each generating unit that can be used for secondary frequency regulation of the automatic generation control system.

[0034] The power generation units of the present invention include thermal power generation units, hydropower generation units, wind power stations and photovoltaic stations; therefore, the spare capacities of the four power generation units need to be calculated separately.

[0035] The present invention calculates the spare capacity of each power generation unit that can be used for secondary frequency regulation of the automatic power generation control system according to the following two situations according to the fluctuation of the power grid frequency:

[0036] Scenario 1: When the grid frequency drops due to active power shortage, the spare capacity of each generating unit that can be used for secondary frequency regulation of the automatic power generation control system is calculated according to the following formula:

[0037]

[0038] Where P wt,avl It is the spare capacity of the wind farm station that can be used for secondary frequency regulation of the automatic power generation control system; P wt,N is the rated capacity of the wind farm; K WT is the droop control coefficient of the wind farm; Δf is the grid frequency deviation; d wt is the primary frequency regulation dead zone of the wind farm station; H WT is the virtual inertia control coefficient of the wind farm; P pv,avl It is the spare capacity of the photovoltaic station that can be used for secondary frequency regulation of the automatic power generation control system; P pv,N is the rated capacity of the photovoltaic station; K PV is the droop control coefficient of the photovoltaic station; d pv is the primary frequency regulation dead zone of the photovoltaic station; H PVis the virtual inertia control coefficient of the photovoltaic station; P th,avl It is the spare capacity of thermal power units that can be used for secondary frequency regulation of automatic power generation control system; P th,N is the rated capacity of the thermal power unit; R th is the adjustment coefficient of the thermal power unit speed governor; d th is the primary frequency regulation dead zone of the thermal power unit; P hy,avl It is the spare capacity of the hydropower unit that can be used for secondary frequency regulation of the automatic power generation control system; P hy,N is the rated capacity of the hydropower unit; R hy is the adjustment coefficient of the hydropower unit speed governor; d hy It is the primary frequency regulation dead zone of the hydropower unit.

[0039] Scenario 2: When the grid frequency rises due to active power surplus, the spare capacity of each generating unit that can be used for secondary frequency regulation of the automatic generation control system is calculated according to the following formula:

[0040]

[0041] A2) Calculate the power allocation factor of each power generation unit according to the different regional adjustment power and the spare capacity of each power generation unit; specifically divided into the following three situations:

[0042] When the area adjusts the power P c Satisfy the conditions: 0<|P c |≤|P wt,avl +P pv,avl |When When |P wt,avl +P pv,avl |<|P c |≤|P wt,avl +P pv,avl +P th,avl +P hy,avl |When When |P wt,avl +P pv,avl +P th,avl +P hy,avl |<|P c |When

[0043] Where α th , α hy , α wt and α pv They are the power allocation factors of thermal power units, hydropower units, wind farms and photovoltaic plants respectively.

[0044] A3) After the grid frequency returns to normal, the power allocation factor of the automatic power generation control system is set proportionally according to the maximum adjustable capacity of each power generation unit; the specific calculation is as follows:

[0045]

[0046] Where P th,max , P hy,max , P wt,max and P pv,max They are the maximum adjustable capacities of thermal power units, hydropower units, wind farms and photovoltaic plants respectively.

[0047] During the process of the grid frequency changing from the beginning to returning to normal, the power allocation factor of the automatic generation control system is updated once in each regional adjustment power calculation cycle.

[0048] A4) Multiplying the power allocation factor of each power generation unit by the regional regulation power of the region where it is located, that is, obtaining the power allocation of each power generation unit in the region.

[0049] Effect description of the present invention:

[0050] Figure 1 The frequency response waveform of the power grid when the active load of the power grid suddenly increases is given. During the period of power grid frequency fluctuation, thermal power units, hydropower units and renewable energy power generation stations respond to the power regulation instructions of the power grid automatic power generation control system to output frequency modulation power. The automatic power generation control power allocation method proposed in the present invention is adopted according to Figure 1 It can be seen that the maximum frequency deviation of the power grid is -0.1546 Hz, and the power grid frequency does not exceed the reasonable operating range. The effectiveness of the method proposed in the present invention has been verified.

[0051] Figure 2 The frequency response waveform of the power grid is given when the active load of the power grid suddenly decreases. Figure 2 It can be seen that the maximum frequency deviation of the power grid is 0.122 Hz, and the power grid frequency does not exceed the reasonable operating range. The effectiveness of the method proposed in the present invention has been verified.

[0052] It can be seen that the automatic power generation control power allocation method proposed in the present invention can calculate the available frequency regulation capacity of each power generation unit, and can obtain the value of the power allocation factor. When the power grid frequency is stable, the value of the power allocation factor is further obtained according to the maximum adjustable capacity of each power generation unit, thereby obtaining a dynamic update strategy for the power allocation factor of the automatic power generation control system. The present invention also takes into account the available frequency regulation capacity of all power generation units in the system, so the calculated power allocation factor can better improve the frequency stability level of the power grid.

[0053] 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 power distribution method for automatic power generation control, characterized in that: The specific steps are as follows: A1) When active power imbalance causes grid frequency fluctuation, calculate the spare capacity of each generating unit that can be used for secondary frequency regulation of the automatic generation control system; A2) Calculating the power allocation factor of each power generation unit according to the different regional adjustment powers and the spare capacity of each power generation unit; A3) After the grid frequency returns to normal, the power allocation factor is calculated according to the maximum adjustable capacity of each generating unit; A4) Multiplying the power allocation factor of each power generation unit by the regional regulation power of the area, the power allocation of each power generation unit in the area is obtained.

2. A power distribution method for automatic power generation control according to claim 1, characterized in that: The power generation units include thermal power units, hydropower units, wind power stations and photovoltaic stations.

3. A power distribution method for automatic power generation control according to claim 2, characterized in that: According to the frequency fluctuation of the power grid, the spare capacity of each power generation unit that can be used for secondary frequency regulation of the automatic power generation control system is calculated in the following two situations: Scenario 1: When the grid frequency drops due to active power shortage, the spare capacity of each generating unit that can be used for secondary frequency regulation of the automatic power generation control system is calculated according to the following formula: Where P wt,avl The wind farm station can be used for secondary frequency regulation of the automatic power generation control system; P wt,N is the rated capacity of the wind farm; K WT is the droop control coefficient of the wind farm; Δf is the grid frequency deviation; d wt is the primary frequency regulation dead zone of the wind farm station; H WT is the virtual inertia control coefficient of the wind farm; P pv,avl It is the spare capacity of the photovoltaic station that can be used for secondary frequency regulation of the automatic power generation control system; P pv,N is the rated capacity of the photovoltaic station; K PV is the droop control coefficient of the photovoltaic station; d pv is the primary frequency regulation dead zone of the photovoltaic station; H PV is the virtual inertia control coefficient of the photovoltaic station; P th,avl It is the spare capacity of thermal power units that can be used for secondary frequency regulation of automatic power generation control system; P th,N is the rated capacity of the thermal power unit; R th is the adjustment coefficient of the thermal power unit speed governor; d th is the primary frequency regulation dead zone of the thermal power unit; P hy,avl It is the spare capacity of the hydropower unit that can be used for secondary frequency regulation of the automatic power generation control system; P hy,N is the rated capacity of the hydropower unit; R hy is the adjustment coefficient of the hydropower unit speed governor; d hy It is the primary frequency regulation dead zone of the hydropower unit; Scenario 2: When active power surplus occurs and the grid frequency rises, the spare capacity of each generating unit that can be used for secondary frequency regulation of the automatic generation control system is calculated according to the following formula:

4. A power distribution method for automatic power generation control according to claim 3, characterized in that: In step A2), the power allocation factor of each power generation unit is calculated according to the following method for different regional power regulation situations. c Satisfy the conditions: 0<|P c |≤|P wt,avl +P pv,avl |When When |P wt,avl +P pv,avl |<|P c |≤|P wt,avl +P pv,avl +P th,avl +P hy,avl |When When |P wt,avl +P pv,avl +P th,avl +P hy,avl |<|P c |When Where α th , α hy , α wt and α pv They are the power allocation factors of thermal power units, hydropower units, wind farms and photovoltaic plants respectively.

5. The power distribution method for automatic power generation control according to claim 3, characterized in that: In step A3), the power allocation factor of each power generation unit is calculated as follows: Where P th,max , P hy,max , P wt,max and P pv,max They are the maximum adjustable capacities of thermal power units, hydropower units, wind farms and photovoltaic plants respectively.

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