Single-Phase Active Power Harmonics Filter by Op-Amp Circuits and Power Electronics Devices

Abstract

This paper introduces a new structure for single-phase Active Power Harmonics Filter (APHF) with the simple and low-cost controller to eliminate harmonics and its side effects on low voltage grid. The proposed APHF includes an accurate harmonic detector circuit, amplifier circuit to trap tiny harmonics, switching driver circuit for precise synchronization, and inverter to create injection current waveform, which is extracted from reference signal. The control circuits are based on electrostatic devices consist of Op-Amp circuits. Fast dynamic, simplicity, low cost, and small size are the main features of Op-Amp circuits that are used in the proposed topology. The aim is removing the all grid harmonic orders in which the proposed APF injects an appropriate current into the grid in parallel way. The proposed control system is smart enough to compensate all range of current harmonics. A prototype is implemented in the power electronics laboratory and it is installed as parallel on a distorted grid by the non-linear load (15 APeak-Peak) to verify the compensating of harmonics. The harmonics are compensated from THD% = 24.48 to THD% = 2.86 and the non-sinusoidal waveform is renovated to sinusoidal waveform by the proposed APHF. The experimental results show a good accurate and high-quality performance.

Application of mathematical morphology for power quality improvement in microgrid

“…“E” is used as a stirring window. “E” slides in between the signals relate with the window samples, and sensed quality signals or particular features of the signals . The two common operations such as erosion and dilation are used in the LMMF.…”

“…Therefore, the output signal of the opening‐closing filter is minute, and the closing‐opening filter is big. As shown in Figure 3B, in the planned approach, for minimizing the deviation and for showing the optimum results, the two filters are connected in cascade to form a novel filter by averaging the opening‐closing and closing‐opening transform . To design an LMMF, an iterative approach is chosen.…”

“…In Li et al, the analog‐LPF is used in the detection system, results in system output containing huge errors in the reference signal generation due to the spectral leakage component and the exactness affected over a longer duration. To resolve the above problem, a digital LPF based on infinite‐impulse‐response (IIR) or finite‐impulse‐response (FIR) is used . However, the IIR filter necessitates a feedback loop, to compute the results and by rounding up the solution may hamper the stability of the system.…”

“…However, the IIR filter necessitates a feedback loop, to compute the results and by rounding up the solution may hamper the stability of the system. Similarly, the FIR filter does not necessitate the feedback loop to generate the desired results, but in order to increase the accuracy, the order of the filter may increase . The higher‐order filter with a high cut‐off frequency is also good for better result generation, but it increases the computational burden.…”

A Real-Time Harmonic Extraction Approach for Distorted Grid

“…Nevertheless, there are disadvantages, such as that the frequency should be known in the algorithm, poor robustness against sudden changes in frequency, etc. A simple and high-quality hardware circuit is introduced to extract grid harmonics in [28]. By sending the collected signal to the detection circuit, the circuit acts as a high pass filter.…”