磁控开关型故障限流器偏置电流模糊PID控制

为提高偏置电流系统的控制精度,设计了一种运用模糊PID在线修改控制器参数的新型偏置电流控制系统。该系统集PID控制及模糊控制的优点于一体,具有不需要精确的数学模型就能够快速、精确控制偏置电流的特点。试验证明,利用该控制系统对限流器偏置电流进行控制,限流器的响应速度和限流效果可以得到保证。

Bias Current Control System of the Magnetic-controlled Switcher Type Fault Current Limiter Based on Fuzzy PID

In order to suppress the fault current in the power system,a novel magnetic-controlled switcher type fault current limiter(FCL) for high-voltage electric network is presented.Under normal operation state,the load of the three-phase full-controlled rectifier is an impedance;under fault state,the load becomes an impedance plus even frequency reverse electromotive force due to the even frequency reverse electromotive force generated in the FCL dc bias coil,the dc bias current includes the dc component and even frequency harmonics.Because of the complex nonlinear and parameter variations characteristics of FCL bias current control system,the common PID control methods could not meet the control demands.In order to improve the control precision,a novel bias current control system is designed.According to error and error rate of the controlled variables,the control rules are summed up and a table of fuzzy PID control parameters is deduced using the principle of maximum membership degree.By analyzing the fuzzy PID control parameters in the system running process,the controller can change its parameters online.The system synthesizes the virtues of fuzzy control and PID control,and can control the bias current quickly and precisely without accurate mathematical model.Comparing with the bias current controller using common PID control method,test results show that the fuzzy PID controller can decrease the bias current fluctuation dramatically.By using fuzzy PID controller to adjust the FCL bias current,the current limiting speed and effect can also be demonstrated by experiments.