Abstract
As one of the key technologies to solve the problem of high short-circuit current, the fault current limiter (FCL) has become a research hotspot in China and abroad. The overvoltage and protection measures of the FCL are the key technologies for its application. Therefore, this paper studies the lightning intruding overvoltage and protection measures for a 500 kV FCL based on a high coupled split reactor (HCSR). Firstly, according to the main topology of the system and the 500 kV HCSR-FCL structure, the lightning intruding overvoltage simulation model of the 500 kV station, including the nearby transmission lines, is established on the PSCAD (Power Systems Computer Aided Design) program. Secondly, the lightning overvoltage of the equipment in the station and the components of the HCSR-FCL are simulated and analyzed when the transmission lines nearby are subjected to lightning shielding failure and back flashover. Meanwhile, the influence of the HCSR-FCL on the lightning overvoltage of the equipment in the station are compared and analyzed before and after the HCSR-FCL is installed. The simulation results show that the overvoltage of the equipment in the station and the components of the HCSR-FCL is more serious when the shielding failure occurs in the transmission lines nearby. The HCSR-FCL can reduce the lightning overvoltage of the equipment in the station, but the maximum inter-terminal and inter-arm lightning overvoltage of the HCSR can reach 1064 kV and 790 kV, respectively, under the current limiting state and the current sharing state. Finally, methods of increasing the arresters on the transmission lines side of the HCSR-FCL and shunt capacitor between each module of the HCSR-FCL are proposed to reduce the lightning overvoltage. The lightning impulse withstand voltage of each component of the HCSR is also proposed: The inter-terminal lightning impulse withstand voltage of HCSR is 170 kV. The inter-arm lightning impulse withstand voltage of HCSR is 200 kV. The terminal-to-ground lightning impulse withstand voltage of the HCSR-FCL is 1550 kV.
Highlights
The short-circuit fault current of the 500 kV power grid is becoming higher due to the increase of power grid capacity and density [1,2]
As the first application of the 500 kV high coupled split reactor (HCSR)-fault current limiter (FCL) used in the 500 kV power grid, it is necessary to study the influence of the HCSR-FCL on the lightning overvoltage and insulation coordination of the original kV system equipment and to propose the lighting impulse withstand voltage of the HCSR-FCL
This paper aims to study the influence on other equipment in the 500 kV power grid when the incoming transmission lines are subjected to lightning shielding failure and back flashover after a 500 kV HCSR-FCL connects to a 500 kV power grid
Summary
The short-circuit fault current of the 500 kV power grid is becoming higher due to the increase of power grid capacity and density [1,2]. The FCL based on a high coupled split reactor (HCSR) has become an important choice to limit the short-circuit current in a power grid due to its high technical and economic efficiency. When a short-circuit fault occurs in the power grid system, the circuit breaker of one arm in the HCSR breaks, and the HCSR presents a high reactance, during which the HCSR is working in a current limiting state [10]. As the short-circuit fault current of the 500 kV power system is much higher than that of 220kV power system and the design structure of the 500 kV HCSR and the 220 kV HCSR are different, there are many practical problems in 500 kV HCSR-FCLs to be solved for their application, such as current limiting depth, insulation design, and coordination with 500 kV power grid equipment. As the first application of the 500 kV HCSR-FCL used in the 500 kV power grid, it is necessary to study the influence of the HCSR-FCL on the lightning overvoltage and insulation coordination of the original kV system equipment and to propose the lighting impulse withstand voltage of the HCSR-FCL
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