【摘要】 柔性直流系统以其在输电领域的巨大优势而获得广泛应用．但在直流系统中，短路故障的强冲击性与电力电子器件的脆弱性之间的矛盾异常尖锐，现有保护策略难以同时满足高速动性与高可靠性的要求．本文从控保协同思想出发，基于一种电压钳位原理的直流断路器，提出一种新的故障处理模式，初步探究在柔直系统中控制与保护深度融合的可能性．当发生短路故障时，投入断路器和换流器相配合的限流功能，一方面限制电力电子器件的过流，解决其脆弱性问题；另一方面为保护提供边界，辅助实现故障的快速定位．在甄别出故障线路后，利用断路器的故障切除功能将故障隔离．此方案同时实现了故障限流、保护边界和故障切除3项功能，可有效缓减由于模块化多电平换流器(modularmultilevelconverter,MMC)器件脆弱性所带来的一系列保护问题．在PSCAD/EMTDC中搭建四端双极柔性直流电网模型，仿真结果表明，本控保协同方案能在5 ms内准确识别并隔离故障线路，而且具有较强的耐受过渡电阻能力．更多还原

【Abstract】 Flexible direct-current(DC)systems are widely employed because of their advantages in the field of power transmission. However,when a short circuit occurs in such systems,the contradiction between the surge of fault current and the fragility of power electronic devices is acute,making it difficult for existing protection strategies to simultaneously meet the requirements of high mobility and reliability. Starting from the concept of control and protection coordination,this study proposes a new fault handling mode for DC circuit breakers based on the voltage clamping principle and preliminarily explores the possibility of deep integration of control and protection in flexible DC systems. When a fault occurs,the input of the current limiting function combined with the circuit breaker and inverter can limit the overcurrent of the power electronic device and solve the fragility problem of the device. Alternatively,it provides a boundary for the protection to realize the rapid location of the fault. After identifying the fault line,the fault removal function of the circuit breaker isolates the fault. This scheme realizes the three functions of fault current limiting,protection boundary,and fault removal and can be used to solve several protection problems caused by the fragility of modular multilevel converter(MMC) devices. In the end,a four-terminal bipolar flexible DC grid model was constructed in PSCAD/EMTDC. The simulation results indicate that the proposed control and protection coordination scheme can accurately identify and isolate faulty line within 5 ms,demonstrating robust resilience to transient resistance.更多还原