HVDC transmission system has considerable impact on the surrounding power transformers when the system is running in the unipolar ground mode, which will cause the DC magnetic biasing phenomenon on transformers. This ...HVDC transmission system has considerable impact on the surrounding power transformers when the system is running in the unipolar ground mode, which will cause the DC magnetic biasing phenomenon on transformers. This problem would be more serious, after commission and operation of UHVDC transmission system in China. According to the Guangdong power grid under the influence of DC magnetic bias seriously, but little research about the using of blocking device, this paper proposed an optimization scheme about the usage of blocking device combination. Firstly, the subject studied the method of suppressing transformer neutral point DC depending on analysis the mechanism of magnetic biasing, and then found out the changes of power grid after using the capacitance blocking device which is popular used by Guangdong power grid. The particle swarm optimization (PSO) has been used to find a better way to suppress the DC in power grid, and combined with NSGA to solve the mixed integer programming problem. The final data validation of this method is valuable in engineering application.展开更多
针对高压直流(high voltage direct current,HVDC)输电网直流故障处理中存在的耗时长且影响范围较广等问题,提出了基于形态学梯度与故障阻断换流器(fault blocking converter,FBC)的HVDC输电网故障处理方法。首先,利用多分辨形态学梯度...针对高压直流(high voltage direct current,HVDC)输电网直流故障处理中存在的耗时长且影响范围较广等问题,提出了基于形态学梯度与故障阻断换流器(fault blocking converter,FBC)的HVDC输电网故障处理方法。首先,利用多分辨形态学梯度算法提取故障电流信号特征,并进行滤波处理以消除噪音干扰;然后,设计了基于FBC的HVDC直流网故障处理策略,结合FBC与高速开关实现快速且有选择性地处理直流故障;最后,利用PSCAD模拟HVDC输电网直流故障。试验结果表明,所提方法的故障处理耗时仅为10 ms,准确率高达95%,能够高效且准确地处理故障。展开更多
直流系统是支撑高比例新能源接入与灵活高效用能的重要技术方向。固态式直流断路器(solid state DC circuit breaker,SSCB)具有开断速度极快、无电弧、寿命长等优点,在中低压直流系统的故障保护中得到广泛应用。随着电力电子器件的发展...直流系统是支撑高比例新能源接入与灵活高效用能的重要技术方向。固态式直流断路器(solid state DC circuit breaker,SSCB)具有开断速度极快、无电弧、寿命长等优点,在中低压直流系统的故障保护中得到广泛应用。随着电力电子器件的发展,固态式直流断路器的拓扑结构、工作性能也在不断进步。为此基于逆阻型集成门极换流晶闸管(intergated gate commutate thyristor,IGCT),提出了一种新型的固态式直流断路器结构及设计方法,通流支路采用逆阻IGCT反并联结构实现双向通流,缓冲支路采用金属氧化物避雷器(metal oxide varistor,MOV)-电容结构来抑制过电压,吸能支路采用MOV吸收系统能量。进一步地,给出了关键元器件的参数设计方法,并验证了有效性;设计了性能良好的重力热管散热器,单个模块散热功率可达700 W;提出了主被动结合的控保策略,提高断路器的保护性能。最后,研制了固态式直流断路器样机,可用于750 V以内的低压直流系统,额定通流可达2 kA,可在百微秒内开断10 kA故障电流,成本低、体积小、高可靠,具有良好的应用前景。展开更多
文摘HVDC transmission system has considerable impact on the surrounding power transformers when the system is running in the unipolar ground mode, which will cause the DC magnetic biasing phenomenon on transformers. This problem would be more serious, after commission and operation of UHVDC transmission system in China. According to the Guangdong power grid under the influence of DC magnetic bias seriously, but little research about the using of blocking device, this paper proposed an optimization scheme about the usage of blocking device combination. Firstly, the subject studied the method of suppressing transformer neutral point DC depending on analysis the mechanism of magnetic biasing, and then found out the changes of power grid after using the capacitance blocking device which is popular used by Guangdong power grid. The particle swarm optimization (PSO) has been used to find a better way to suppress the DC in power grid, and combined with NSGA to solve the mixed integer programming problem. The final data validation of this method is valuable in engineering application.
文摘针对高压直流(high voltage direct current,HVDC)输电网直流故障处理中存在的耗时长且影响范围较广等问题,提出了基于形态学梯度与故障阻断换流器(fault blocking converter,FBC)的HVDC输电网故障处理方法。首先,利用多分辨形态学梯度算法提取故障电流信号特征,并进行滤波处理以消除噪音干扰;然后,设计了基于FBC的HVDC直流网故障处理策略,结合FBC与高速开关实现快速且有选择性地处理直流故障;最后,利用PSCAD模拟HVDC输电网直流故障。试验结果表明,所提方法的故障处理耗时仅为10 ms,准确率高达95%,能够高效且准确地处理故障。
