含直流断路器的柔直配电网过电压与绝缘配合

Overvoltage and insulation coordination of flexible DCdistribution network with DC circuit breaker

随着分布式能源的不断应用与普及,直流配电必将成为未来配用电系统的主流形式。作为一种新型的配电系统,柔直配电的过电压与绝缘配合亟须进一步研究和完善,中压直流断路器的加入也导致了系统的操作过电压暂态特性发生了根本变化,须对含直流断路器的柔直配电网操作过电压分布特性及绝缘配合展开分析。首先,构建了±10 kV环网型柔直配电网的电磁暂态仿真模型,设计了基于含直流断路器的保护动作方案;其次,基于保护动作方案,对±10 kV环网型柔性直流配电系统进行操作过电压的仿真分析,得到其幅值的水平空间分布特性和关键位置最大过电压的决定性工况,并提出±10 kV环网型柔性直流配电系统的绝缘配合方案;最后,对直流断路器动作影响下直流电缆护套的暂态感应过电压展开仿真分析。研究表明,直流断路器的加入提高了直流配电网的可靠性和灵活性,避雷器和电缆金属护层保护器的布置方案也得到进一步的优化,对环网型柔直配电网的绝缘配合方案设计有较大意义。

With the continuous application and popularization of distributed energy,DC power distribution will become the mainstream form of future power distribution system.As a new type of power distribution system,the overvoltage and insulation coordination of flexible DC power distribution urgently needs further research and improvement.The addition of medium-voltage DC circuit breakers has also led to fundamental changes in the operating overvoltage transient characteristics of the system.It is necessary to analyze the operating overvoltage distribution characteristics and insulation coordination of the flexible DC distribution network with DC circuit breakers.Firstly,the electromagnetic transient simulation model of±10 kV ring-network flexible DC power distribution network is constructed,and the protection action scheme based on DC circuit breaker is designed.Then,the±10 kV ring network flexible DC power distribution system is simulated and analyzed for operating overvoltage,horizontal spatial distribution characteristics of its amplitude and the decisive working condition of the maximum overvoltage at key positions are obtained,insulation coordination scheme of the±10 kV ring network flexible DC power distribution system is proposed.Finally,the simulation analysis of the transient induced overvoltage of the DC cable sheath under the influence of the action of the DC circuit breaker is carried out.The results show that the addition of DC circuit breakers improves the reliability and flexibility of DC distribution network,and the layout of arrester and cable metal shield protector is further optimized,which is of great significance to the design of insulation matching scheme of flexible direct distribution network of ring network.