Research On Topology Design And Application Of High Voltage DC Circuit Breaker Based On Resistive Superconducting Current Limiter

In recent years,with the development of renewable energy technology and the continuous increase of power grid capacity,traditional AC transmission has been unable to meet the needs of society.The development of power electronic devices and the advantages of DC transmission have led to the rapid development of HVDC transmission technology.As the key equipment of HVDC transmission system,the research and development of HVDC circuit breaker is imminent.At present,the technical difficulties in the research and development of DC circuit breakers mainly include: DC power does not have a natural zero-crossing point,and arc extinguishing is difficult after a fault occurs;Fault breaking of DC system;it is difficult to balance the rapidity of fault detection and the reliability of fault breaking.This paper introduces the current research status of DC circuit breakers at home and abroad in detail,compares and analyzes the topology,working principle,advantages and disadvantages of the three types of DC circuit breakers currently existing,and points out that the hybrid high-voltage DC circuit breaker has a small on-state loss,the advantages of large breaking capacity and arc-free breaking have become the current research trend,but there are still deficiencies limited by technology.In order to take into account the quickness and reliability of the circuit breaker,and at the same time have a better current limiting effect,a resistive superconducting current limiter with simple structure,fast response speed,automatic triggering and high impedance after quenching is introduced to limit the DC current.The rise rate and peak value of the system fault current,while ensuring that the circuit breaker can act quickly and respond reliably after the system fails.In this paper,the superconducting technology and the DC breaking technology involved in the research are expounded in detail,which provides the theoretical basis and technical support for the design of the circuit breaker.Aiming at the insufficient breaking performance of existing hybrid HVDC circuit breakers,two topology structures of HVDC circuit breakers based on resistive superconducting current limiters are proposed.The proposed circuit breaker combines the superconducting characteristics of the superconducting current limiter,the large breaking capacity of the mechanical switch and the flexible and controllable all-solid-state electronic devices,etc.,and effectively suppresses the rise rate and peak value of the short-circuit current;the circuit breaker topology is reasonably configured with full control and Semi-controlled electronic devices,flexible control and high reliability;adding components such as commutation capacitors and current-limiting inductors accelerates the commutation speed,reduces the breaking time,and greatly reduces the energy absorption rate of the arrester.The capacitor self-charging loop is added to the topology structure,which effectively solves the problem of charging the commutation capacitor.Through the mathematical derivation modeling of each working stage of the circuit breaker and the parameter design of related devices,the short-circuit fault model of320 k V/1.6k A HVDC system is built in PSCAD/EMTDC simulation software,and the current limiting of the resistive superconducting current limiter is simulated and analyzed.Characteristics and the breaking characteristics of the circuit breaker topology proposed in this paper,the simulation results show that the larger the quench resistance value is,the better the current limiting effect of the circuit breaker is,but the voltage impact on the current limiter is greater.Compared with the traditional hybrid HVDC circuit breaker,the peak value of the fault breaking current of the circuit breaker proposed in this paper is 3.5k A,a decrease of 41.7%,and the energy absorbed by the arrester is 0.75 MJ,a decrease of 90%.The total fault time is 5.9ms,and a total of 1490 power electronic devices are used.At the same time,the fault current rise rate is significantly reduced,arc-free breaking is completed,and better breaking characteristics and economy are shown.