US 12,348,043 B2
Method and apparatus for allocating virtual inertia in photovoltaic cluster
Hui Fan, Hebei (CN); Jifeng Liang, Hebei (CN); Peng Luo, Hebei (CN); Tiecheng Li, Hebei (CN); Siming Zeng, Hebei (CN); Qian Zang, Hebei (CN); and Leibao Wang, Hebei (CN)
Assigned to State Grid Hebei Electric Power Co., Ltd. Research Institute, Shijiazhuang (CN); State Grid Hebei Electric Power Co., Ltd., Shijiazhuang (CN); and State Grid Corporation of China, Beijing (CN)
Appl. No. 17/782,999
Filed by State Grid Hebei Electric Power Co., Ltd. Research Institute, Hebei (CN); State Grid Hebei Electric Power Co., Ltd., Hebei (CN); and State Grid Corporation of China, Beijing (CN)
PCT Filed Mar. 28, 2022, PCT No. PCT/CN2022/083271
§ 371(c)(1), (2) Date Jun. 7, 2022,
PCT Pub. No. WO2023/178707, PCT Pub. Date Sep. 28, 2023.
Claims priority of application No. 202210291076.9 (CN), filed on Mar. 23, 2022.
Prior Publication US 2024/0186794 A1, Jun. 6, 2024
Int. Cl. H02J 3/38 (2006.01); H02J 3/28 (2006.01)
CPC H02J 3/381 (2013.01) [H02J 3/28 (2013.01); H02J 2203/20 (2020.01); H02J 2300/24 (2020.01)] 14 Claims
OG exemplary drawing
 
1. A method for allocating virtual inertia in a photovoltaic cluster, comprising:
determining required virtual inertia based on a frequency change rate monitored at a grid connection point of a photovoltaic grid-connected system;
obtaining values of indexes that affect virtual inertia provided by each virtual synchronous generator (VSG) control unit in a photovoltaic cluster of the photovoltaic grid-connected system;
determining, by using a predetermined function equation, a function value corresponding to each index, wherein the function equation is determined by constructing an objective function, determining, based on the objective function, a membership function corresponding to each VSG control unit, establishing a small-signal model of the system, analyzing stability of parameters in the membership function with a root locus analysis method, and determining an optimal parameter;
determining an allocation proportion of the required virtual inertia in each VSG control unit based on the function value corresponding to each index; and
presetting a threshold of the frequency change rate, and starting virtual inertia control when the frequency change rate exceeds the threshold;
wherein the step of determining, by using a predetermined function equation, a function value corresponding to each index comprises:
determining, by using the following function equation, the function value corresponding to each index:

OG Complex Work Unit Math
wherein x represents the index; u(x) represents the function value; p10, q10, C10, p11, q11, and C11 represent determined parameters; and a, b, c, and d represent boundaries for dividing a working region of the energy storage device in a state of charge (SOC), wherein a section from a to b represents a discharging state of the energy storage device, a section from b to c represents a normal state of the energy storage device, and a section from c to d represents a charging state of the energy storage device.