Research Of Shunt Active Power Filter Based On DSP Control

Along with the rapid development of power electronic technique, an increasing number of power electronic equipments are widely used in industry and agriculture production and people's daily life. The power electric equipments have the characteristic of nonlinear loads. They give rise to much harmonics and reaction power current into power grid and bring about a lot of power quality problems.Traditional LC passive power filters should be replaced by active power filter in the future, because of its shortage that it can only absorb the harmonics of fixed frequency easily make parallel resonance. Active power filter has an advantage and it can achieve the function of harmonics and reaction power compensation. And it can also well compensate the objects of which frequency and amplitude changes at the same time, this overcomes the shortage of the LC passive power filters very much.Firstly, the categorization, operation principle and main circuit's topologies of active power filter are introduced in this paper. The harmonic detection method based on instantaneous reactive power theory is researched in detail. Concerning its shortcoming, a novel harmonic detection method based on adaptive neural networks is proposed.The math models of three-phase three-wire and three-phase four-wire capacitance- midpoint active power filter are founded separately, on the base the control strategies suitable for different topologies are discussed and researched. For three-phase three-wire systems two control strategies are researched, strategies based on load current detection and on DC capacitances'voltage detection. For three-phase four-wire systems, a harmonic detection and control method based on zero-order current abruption are applied.PSIM and MATLAB models corresponding to the detection methods and control strategies proposed in this paper are given, their validity and feasibility are validated by simulation. Finally a prototype based on DSP is designed. The experiments of harmonic current detection method and control strategy based on instantaneous reactive power theory have done on it, and the result verifies the theory'validity.