Research On Parallel Digital Reactor Of10kV Electrified Railway Signal Light System

With the rapid development of railway industry in our country，Requirements on stability of the railway signal light system are becomingincreasingly. Due to the rail power transmission line capacitance effect, there willbe produce relatively large capacitive current and lead to the phenomena such aspower frequency voltage of the transmission line ends rise and no-load resectioncircuit cause operating over voltage. These phenomena would endanger thestability of the signal light system. Therefore, research on reactive powercompensation device which can counteract the rail power transmission linecapacitance effect relatively accurate based on the reactive power state of thesystem cause the attention of the people.This paper puts forward a kind of parallel digital reactor of10kV electrifiedrailway signal light systems based on PWM control technology. It can output therequired perceptual reactive power smoothly according to the power systemreal-time reactive state. This digital reactor changes the inductive current whichflows through the reactor’s inductance coil by controlling secondary side voltageinverter to offset the grounding capacitive current. So it can complete dynamicreactive power compensation.The digital reactor main circuit is composed of two reactors in series,including one with a secondary coil used to±30%of current regulation. Controlcircuit is a single-phase full bridge inverter which is made up of each bridge armcomposed of IGBT and the diode. This inverter connects secondary coil andoutput current according to the actual adjust demand.The controller can controlthe inverter output based on the result which is calculated according to samplingvalues on the voltage and current, control switch state according to the circuit’sworking condition and working condition. And DSP6713is used as CPU which iscooperated with CPLD and ADC, to make the calculation on500points output current per cycle be realized and2-5kHz PWM modulation signal be sent out.In this paper, digital reactor uses the acquisition of the voltage and current ofthe reactor primary side to make the reactor primary side inductance coil outputthe needed reactive current for compensation by PI regulation. And we also usePI regulation to adjust the active charging current to make the dc side capacitorvoltage of the inverter remain stable.The experimental results show that parallel digital reactor of10kVelectrified railway signal light systems in this paper reached well to adjust theaction of making power penetration line reactive power balance. It satisfied therequirements on stability of the railway signal light system.It has the advantagesof simple configuration, rapid response and wide range continuously ofinductance change.