Adaptive DC-link voltage controlled LC coupling hybrid active power filters for reactive power compensation

摘要

An adaptive dc-link voltage controlled LC coupling hybrid active power filter (LC-HAPF) for reactive power compensation includes: two dc capacitors to provide dc-link voltage; a three-phase voltage source inverter to convert dc-link voltage into compensating voltages; three coupling LC circuits to convert compensating voltages into currents; and an adaptive dc voltage controller with reactive power compensation control algorithm. The control algorithm includes: first, calculating required minimum dc-link voltage in each phase with respect to loading reactive power; three-phase required minimum dc-link voltage will be maximum one among their minimum values; compare it with predetermined voltage levels to determine final reference dc-link voltage. A dc-link voltage feedback P/PI controller outputs dc voltage reference compensating currents. An instantaneous power compensation controller outputs reactive reference compensating currents. The final reference compensating currents will be sum of them. A PWM circuit provides LC-HAPF adaptive dc-link voltage control and dynamic reactive power compensation.

主权项

1. An adaptive dc-link voltage controlled LC coupling hybrid active power filter (LC-HAPF) for reactive power compensation connected in parallel with an inductive load powered by a power source, comprising:
two dc capacitors to provide dc-link voltage; a three-phase voltage source inverter to convert the dc-link voltage into compensating voltages; three coupling LC circuits to convert the three-phase compensating voltages into compensating currents, and then to be injected to the connection points between the power source and the load; and
an adaptive dc voltage controller with reactive power compensation control algorithm comprising:calculating the phase instantaneous loading reactive power −qLx/2 (subscript ‘x’ denotes phase a,b,c) based on instantaneous load voltage vx and load current iLx;obtaining the phase loading reactive power QLxf=−qLxf/2 after passing the phase instantaneous loading reactive power −qLx/2 through a low pass filter;calculating the required minimum dc-link voltage Vdc—min x for compensating the phase loading reactive power QLxf in each phase based on the calculated phase loading reactive power QLxf, reactive powerQcxf_PFprovided by the coupling LC circuit and the instantaneous load voltage Vx using the following equation;Vdc_min⁢⁢x=2⁢2⁢Vx⁢1-QLxfQcxf_PF selecting the three-phase required adaptive minimum dc-link voltage Vdc—min that will be the maximum one among the calculated Vdc—min x in each phase, as given below
Vdc—min=max(Vdc—min a,Vdc—min b,Vdc—min c)andcomparing Vdc—min with predetermined voltage levels (Vdc1, Vdc2, . . . Vdcmax, Vdc1