A topology of series active power filter (SAPF) based on a single phase half-bridge cascaded multilevel inverter is proposed to compensate voltage harmonics of the load connected to the point of common coupling (PCC). The main parts of the inverter are presented in detail. Any voltage reference can be easily obtained by a simple control with the proposed inverter. Therefore, the inverter acts as a harmonic source when the reference is a non-sinusoidal signal. A prototype of 15-level inverter based SAPF is manufactured without using a parallel passive filter (PPF) as it is intended to represent the compensation capability of the SAPF by itself. The load connected to PCC whose voltage is non-sinusoidal is filtered both in simulation and experimental studies. The validity of the proposed inverter based SAPF is verified by simulation as well as experimental study. Both simulation and experimental results show that the proposed multilevel inverter is suitable for SAPF applications.
- Active power filter
- Multilevel inverter
- Harmonic compensation
- Half-bridge cascaded
- Power quality
Figure 1. The basic configuration of the proposed system.
EXPECTED SIMULATION RESULTS:
Figure 2. Simulation results – Set I a) V pcc and VhPCC before compensation (50 V Idiv), b) inverter and load voltage after compensation (50 V Idiv).
Figure 3. Simulaton results – Set 2 a) V pcc and V”pcc before compensation (50 V ldiv), b) inverter and load voltage after compensation (50 V Idiv).
This paper proposes a single phase half-bridge cascaded multi level inverter based SAPF. The multi level inverter topology and operation principle is introduced. With the proposed topology, the number of output levels can easily be increased. Switching angles of the semiconductor devices used in the inverter are also obtained by a simple method. A SAPF with the proposed inverter topology is simulated under different harmonic distortion levels of PCC. The aim of the simulation is to compensate the load voltage harmonics connected to PCc. In addition to the simulations, the proposed SAPF prototype is designed. Using this prototype, experimental study is performed. Microchip dsPIC30F6010 is preferred as a controller in this prototype. It is a commercially available and inexpensive microcontroller. The presentable results of the proposed system are summarized as follows;
- The THD values obtained from simulation study is similar to experimental results.
- The results of simulation and experimental studies demonstrate the accuracy of the simulation study.
- The THD values after compensation is reduced to 2.88% and 3.07% by using the proposed inverter based SAPF. After compensation, the waveform of load voltage is almost sinusoidal.
- A highly distorted sinusoidal waveform with a THD value of 24.12% is compensated with the proposed inverter based SAPF and the THD value is reduced to 3.07%. This shows that the proposed inverter is suitable for SAPF applications.
Both simulation and experimental studies show the validity of the proposed inverter as a SAPF.
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