North China Electric Power University

Zengping Wang

Jing Yan Ma

Tong Jiang

Tong Wang

Yufeng Zhao

Shuwei He

Zhencun Nie

Jialun Li

Qixun Yang

The present disclosure provides a method and device for calculating fault measurement impedance of a hybrid-connected grid-following and grid-forming wind power system. The method includes: obtaining characteristics of the grid-following and grid-forming converters and a corresponding low voltage ride-through control strategy; establishing an equivalent circuit under a corresponding fault state; conducting a simplified analysis on the wind power system to obtain an equivalent network diagram; obtaining a sub-circuit diagram of each power source excitation acting alone; obtaining short-circuit currents on both sides of the corresponding system and a grid connection point voltage; superimposing to obtain total short-circuit current on both sides of the wind power system and total grid connection point voltage; and obtaining a measurement impedance at a protection installation location on the new energy source side. The method can accurately calculate the measurement impedance value at the protection installation location after the wind power system has fault.

Method and device for calculating fault measurement impedance of hybrid-connected grid-following and grid-forming wind power system

The invention relates to a fault transient features optimization method and system of AC/DC system based on dissipated energy, which belongs to the HVDC transmission technology and is used to solve the problem that the DC pulsed current is too high and the generator power angle swing of the AC system on the rectifier side is too large during the process of the HVDC transmission system restart on fault. The method includes the following steps: obtaining the output current and outlet bus voltage of the generator during the whole process of fault recovery of the AC/DC system under the current control parameters when adjusting the control parameters of the rectifier, and obtain multiple sets of control parameters and their corresponding output current and outlet bus voltage of the generator during the whole process of fault recovery of the AC/DC system; for each set of control parameters, calculating cumulative value of dynamic dissipated energy of the generator under the set of control parameters based on the output current and outlet bus voltage of the generator during the whole process of DC system fault recovery; selecting the set of control parameters that minimizes the cumulative value of dynamic dissipated energy of the generator as the optimal control parameter in the process of fault transient features optimization.

Fault transient features optimization method and system of AC/DC system based on dissipated energy

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Beijing, China

Zengping Wang