用于低电压问题治理的柔性交直流切换配电系统设计

Design of Flexible AC/DC Switching Distribution System for Solving Low-voltage Problems

为解决用电负荷增加带来的配电系统末端低电压问题,提出了柔性交直流切换配电系统,可在提高电压质量的同时保证系统运行灵活性。该配电方案通过在配电线路首末两端装设变流器和断路器组,按需运行于直流配电模态或者交流配电模态。首先,针对交直流配电模态相互切换过程中负荷供电的可靠性,对变流器控制系统和断路器动作时序进行设计,实现切换过程中负荷电压的平滑过渡。其次,为避免极端工况下断路器组的误动作,提出了基于事件触发和非特征次谐波检测两种判断逻辑,保障系统在极端工况下稳定运行。最后,针对错误切换过程潜在的短路故障,在控制和硬件层面设计了保护措施,避免系统设备损坏。MATLAB/Simulink仿真以及实验结果验证了切换配电方案和保护方案的有效性。

To solve the end-user low-voltage problem in the distribution system caused by increasing load, a flexible AC/DC switching distribution system is proposed, which can improve the voltage quality and ensure the system operation flexibility. The distribution scheme is designed to operate in DC distribution mode or AC distribution mode as required by installing converters and circuit breaker groups at both ends of the distribution line. First, in view of the power supply reliability of load during the switching process of AC/DC distribution modes, the converter control system and the operation sequence of circuit breakers are designed to realize the seamless transition of load voltage during the switching process. Secondly, in order to avoid the misoperation of circuit breaker groups under extreme conditions, two judgment logics based on event triggering and non-characteristic harmonic detection are proposed to ensure the stable operation of the system under extreme conditions. Finally, in view of the potential short-circuit fault during the wrong switching process, protection measures are designed at the control and hardware levels to avoid system equipment damage. MATLAB/Simulink simulation and experimental results verify the effectiveness of the switching distribution scheme and protection scheme.