Hysteresis current control of cascaded h bridge inverter based shunt active power filter

Abstract

quotBackground: Non-linear load feeds harmonics into the distribution system. Conventionally, two-level voltage source inverter based shunt active power filter is used to mitigate the harmonics. The hysteresis current control method is more popular among all current control methods. The hysteresis current control method has several advantages such as ease of implementation in software as well as in hardware, immune to load parameter variation and faster dynamic response. For medium voltage and high power applications, multilevel inverter based shunt active power filter is used. A three-level hysteresis current control is applied for control of compensating current in multilevel inverter based shunt active power filter. The HCC in its most simplified form has fixed hysteresis band and hence suffers from large variations in switching frequency. This is reduced by some extent in basic three-level HCC method, but the basic three-level hysteresis current control method is suffered from a high value of current tracking error. newline newlineAim: To reduce the value of maximum switching frequency, variation in the switching frequency in hysteresis current control, Improve the performance of the three-level hysteresis current controller in terms of % THD and reduce the standard deviation of the switching frequency with reducing the current tracking error. newline newlineMethod: A Simulation model of cascaded three-level inverter based shunt active power filter is prepared in PSIM simulator. In basic three-level hysteresis current control, two hysteresis bands are specified which are placed in the opposite direction to each other, and there is no overlapping between these two bands. Therefore, the actual current does not closely follow the reference current due to which the current tracking error is increased. In the proposed modified three-level hysteresis current control method, there is an overlapping in the bands.