Dynamicmodelingand control strategies of upqcfor simultaneous voltage andcurrent compensation

Abstract

Today utility network still significantly suffers from some low newlinepower quality factors. The poor reliability and quality of power supply may newlinecause many complex and serious problems. And high quality of power has newlinebeen more and more required by increasing number of sensitive loads. newlineHarmonics generated by nonlinear loads, voltage sag, and high frequency newlinecomponents caused by switched capacitors are some known sources seriously newlinedegrading the quality of supply in the power network. Power system can employ many attractive applications of power newlineelectronics technologies for power quality improvement. Voltage-source newlineconverter based custom power devices are increasingly being used in custom newlinepower applications to mitigate power quality problems in power distribution newlinesystems. One modern and very promising solution is the unified power quality newlineconditioner. newlineUnified Power Quality Conditioner(UPQC) is a custom power newlinedevice that consists of shunt and series converters connected back to back on newlinethe dc side and deals with load current and supply voltage imperfections. It newlinecan compensate for power quality problems such as voltage harmonics, newlinevoltage unbalance, voltage flickers, voltage sags, voltage swells, current newlineharmonics, current unbalance, reactive current, etc. The active power filtering newlinehas proven to be one of the best solutions for mitigation of major power quality problems. The operation of UPQC isolates the utility from current newlinequality problems of load and in the same time, isolates the load from voltage newlinequality problems of utility. The shunt active filter is utilized to overcome all current related newlineproblems, such as current harmonics, reactive current and current unbalance. newlineWhereas, all voltage related problems, such as voltage harmonics, voltage sag newlineand swell, and voltage unbalance, are handled by using the series active filter. The UPQC is controlled in such a way that the voltage at load bus is always newlinesinusoidal and has a desired magnitude. newline