AUTOMATIC REACTIVE-POWER CONTROL DEVICE Russian patent published in 2001 - IPC

FIELD: ac moving consists; electric-locomotive power-factor correction. SUBSTANCE: device depending for its operation on approaching input-current waveform to that of supply voltage including higher harmonics at the same time reducing input-current ripples has load, reactive-power source, supply mains voltage and current sensor, pulse synchronizing unit, pulse-phase control unit, four multipliers, three integrators, square-root computer, and comparison gate. Reactive-power source has series-connected inductance coil, capacitor, and two thyristors connected in parallel opposition; supply mains current and voltage sensor has potential transformer and current transformer. Load is connected to supply mains through current transformer and in parallel with circuit set up of series-connected inductance coil, capacitor, and thyristors which are connected in parallel opposition. Potential transformer is connected in parallel with supply mains and its output is connected to first and second inputs of first multiplier, first input of third multiplier, and to input of pulse synchronizing unit. Current transformer output is connected to first and second inputs of second multiplier and to second input of third multiplier. Outputs of first through third multipliers are coupled with first inputs of integrators. Outputs of first and second integrators are connected, respectively, to inputs of fourth multiplier whose output is connected through square- root computer to first input of comparison gate. Comparison-gate output is coupled with input of pulse-phase control unit. Output of pulse synchronizing unit is connected to second inputs of integrators ; output of third integrator is connected to second input of comparison gate; output of pulse-phase control unit is connected to reactive-power source thyristors. EFFECT: improved reactive-power correction at sine-wave and non-sine- wave supply voltages under various operating currents and voltages; reduced power requirement. 1 cl, 1 dwg