ABSTRACT: This work describes artificial neural network (ANN) based control algorithm for three phase three wire shunt active power filter (SAPF) to compensate harmonics and improve power quality. System consists of three phase insulated gate bipolar transistors IGBT based current controlled voltage source inverter (CC-VSI), series coupling inductor and self supported DC bus. Increasing application of non-linear loads causes power quality problem. SAPF is one of the possible configurations to improve power quality. Traditional SAPF have PLL based unit template generator for extraction of fundamental signal. Traditional PLL needs to be tuned to obtain optimal performance for frequency estimation. It requires initial assumptions for fundamental frequency and minimum frequency. With varying frequency, it can’t be dynamically tuned for optimal performance. A new ANN based fundamental extraction based on Lavenberg Marquardt back propagation algorithm is proposed. Proposed SAPF is modeled in Simulink environment. Simulated results show the capability of proposed system.
- Shunt Active Power Filter
- Artificial Neural Networks
- Indirect Current Control Technique
- Power Quality
Fig.1. Proposed system configuration block with SAPF
EXPECTED SIMULATION RESULTS:
Fig.2. Source voltages
Fig.3. Unbalanced load voltages
Fig.4. Unbalanced load currents
Fig.5. Simulation result for proposed system under non linear with
unbalance load condition
Fig.6. DC link voltage
Fig.7. Active power
Fig.8. Reactive power
Fig.9. Power factor
Fig.10. Harmonic spectrum of load current before compensation for three phase SAPF with non linear load
Fig.11. Harmonic spectrum of source currents (phase a, phase b phase c respectively) after compensation for ANN based three phase APF with non linear load
Fig.12. Harmonic spectrum of source currents (phase a) after compensation for ANN based three phase APF with non linear load with unbalance
ANN based phase-locking scheme has been proposed in this paper to control three phase-three wire shunt APFs. Widrow-Hoff weights updating algorithm has been incorporated to reduce calculation time in estimation of harmonic components. To validate effectiveness of proposed approach for real-time applications, indirect current control theory based controller has been developed. Design parameters of power circuit and control circuit have been calculated and robustness of proposed system has been established with Matlab/Simulink. Simulation result and spectral response show that, obtained source current THDs is below 5% as prescribed by IEEE-519 standard. Dynamic performance of proposed approach has been found satisfactory under sudden change in load and frequency.
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