Compensation of harmonics and reactive power using shunt active power filter

Today, expansive using of non-linear loads increases existing of troubles in power quality. Harmonic pollution and drawing reactive power lead those troubles. Conventionally, harmonic compensation is carried out by using of passive filters. On the other hand those filters solve problems limitedly. Passive filters have some drawbacks like fixed compensation characteristic and large sizes. Because of whole reasons mentioned, passive filters are inadequate at suppressing harmonics. Advancement on power electronics and micro-processor technologies made active power filters which can simultaneously compensate reactive power and harmonics, used more popularly.In this thesis, a simulation model of two-level inverter based shunt active power filter is built in Matlab/Simulink software to compensate harmonic and reactive power simultaneously. Designed simulation model consists of a balanced grid, two-level inverter, a coupling inductance between grid and inverter, control unit and non-linear loads.Control unit of shunt active power filter extracts required reference signals for compensating reactive power and harmonics by sensing grid voltage and current waves. In this study, fast Fourier method in frequency domain and instantaneous reactive power theory and synchronous reference frame method in time domain are used for reference extracting process. Control of inverter output current is necessary to generate reference signals. In this study, two-level hysteresis band current controller is used as current modulator. Hysteresis band current controller is mostly preferred because of its easy implementation and robust structure. Besides, including undefined and floating switching frequency is the most known disadvantage of it. Each reference extracting method is executed through simulation model and dynamic performance of shunt active power filter is shown by cooperation of two non-linear loads operated at different times. Graphical results are obtained and presented.