Study Of The Current Limiting Device On The Basis Of The Principle Of Forced Current Zero

With the development trend and rapid increase of power grid capacity, the short-circuit current level is increasing rapidly, keeping the steady and reliable operation of the power system is a big challenge. So it is of great importance to limit the short-circuit current effectively.Based on the existing fault current limiter’s studies, simulation and experimental study of the current limiter on the basis of current commutation were carried out in this paper. The one-phase and three-phase control strategy was also proposed. A lkV experimental current limiter prototype was developed, which was successfully experimented in experimental environment.A new kind of current limiting device based on current commutation was proposed in this paper, it consists of a high speed breaker, counter pulse circuits and a limiting resistor. The function of a high speed breaker is to open the fault current fast. The high speed switch can open the current at the forced current zero after a superposition of the corresponding counter pulse circuit. Then the current is commuted to a limiting resistor, the whole current limiting process is completed. According to the short-circuit current phase detection, the sequences coordination of the high speed switch and the counter pulse circuits and the phase rule of three-phase short-circuit current, the control strategy at any phase of the three-phase short-circuit current was presented here. A circuit simulation was established by the Simulink tool of Matlab. A lower current limiting experimental prototype was designed. The simulation and experimental results reflected the whole current limiting process can be controlled within 1.5-2ms. Thus it quickly and effectively limits the damage to the entire system caused by the first peak of the fault current and significantly improves the system stability and the power quality.In this paper, the bottlenecks that exist in the current study on current limiting devices on the basis of the principle of forced current zero were discussed in detail, suggestions related were also listed. At present, in this research area, the main problems include:flow capacity and trigger stability of power devices used in related current limiting devices; fast and accurate control of relay protection and trigger stability; precharged capacitance settings and related impacts of the capacitors mounted on the counter pulse circuits.