Simulation Study On Active Comprehensive Compensation Of Traction Substation

Local three-phase power system supplies power to single-phase load passing by the traction substation.Because of having problems such as high-capacity,diversification,lower power factor and high-order harmonics,single-phase load has influences on local three-phase power system which will bring about negative current,reactive current and harmonic current.The influences will reduce the quality of power supply.Directing at the traction substation,this paper studies on how to eliminate negative current,reactive current and harmonic current together by using active comprehensive compensation and lay the foundation for experimental study and proprietary intellectual property rights of the electric railway about comprehensive compensation.First,the paper analyzes the relationship between voltage and current of Y/>/D balanced transformer,and the relationship between negative sequence current and the two-phase current is got.On the basis of phase-shifting principle,the paper analyzes the matching relationship among inductance,capacitance and resistance when Y/>/D balanced transformer has a pure resistive load,also the effect that load-fluctuation has influence on the unbalance factorε.And on the base of Matlab,the simulation model of the balanced transformer and power supply system of Y/>/D balanced transformer with pure resistive load is set up.By means of the simulation analysis at the condition of normal,open circuited and short circuited,the simulation model of Y/>/D balanced transformer is demonstrated to be correct and acceptable.Second,the paper analyzes and compares active power filter harmonic detection at present. ip-iq detection can be applied in the situation of the supply voltage distortion,but when it is applied to three-phase voltage asymmetry,there are errors in detecting the active component and reactive component.The paper puts forward a new method at the base of ip-iq detection.At the condition of three-phase and four-line,the simulation of the new method is demonstrated to be correct and acceptable on the base of Matlab.Third,the paper analyzes active power filter control method and gives the parameters calculating.Also it sets up and compares the simulation about the two control method.And at the base of hysteresis control,the paper analyzes a new control method which can reduce switching frequency.Fourth,the paper puts forward the structure of three-phase to single-phase balanced transformation on the base of balancing transformer with active power filter And it analyzes the operating principle of the whole system about active power exchanging,harmonic suppression and reactive compensation.The structure consists of balanced transformer and active power filter. According to adjusting the active component between two phases of the balanced transformer,the structure of the system can eliminate the negative-sequence current and realize the balanced by using active power filter.Finally,the paper gives the whole model when the load are linear,nonlinear and changing. According to the simulation,it demonstrates the method of three-phase to single-phase at the base of balancing transformer is effective.