Voltage Related Power Quality Issues Research Articles

Least Mean Fourth Theory-based Dynamic Voltage Restorer for the Mitigation of Voltage Sag and Harmonics

In the present paper, Dynamic Voltage Restorer (DVR) controller using the Least Mean Fourth (LMF) algorithm is presented. The proposed DVR is used for protecting various voltage-sensitive loads from voltage-related power quality issues (i.e. balanced voltage sag, unbalanced voltage sag and voltage harmonic distortion, balanced and unbalanced swell, etc.) in a distribution system. The active and reactive power components of distorted source voltage are extracted using an adaptive LMF-based control algorithm for the calculation of reference load voltage for the voltage source converter (VSC) of DVR. The control algorithm doesn’t require a phase-locked loop (PLL) and thus is less complex, robust and easy to implement. The adopted control algorithm for DVR is verified in MATLAB by simulation studies. The adaptive LMF-controlled DVR produces excellent dynamics response as compared to conventional adaptive Least Mean Square (LMS) and Synchronous reference frame theory (SRFT)-controlled DVR. The convergence rate of the source voltage fundamental active weight component is higher for the proposed adaptive LMF-controlled DVR. Various power quality issues such as balanced sag, unbalanced sag, balanced and unbalanced swell and a combination of these power quality issues are mitigated with the help of the LMF-controlled DVR. The simulation results are verified through real-time experimentation using an OPAL-RT under an RT lab environment.

Performance of DVR Using Optimized PI Controller Based Gradient Adaptive Variable Step LMS Control Algorithm

A custom power device known as dynamic voltage restorer (DVR) has been investigated to operate a distribution system at its desired performance. The distribution system with voltage-related power quality issues in the supply side has been addressed through this article using DVR. Four different grid disturbances, such as voltage sag, swell, unbalances, and distortions, have been taken into account while testing the DVR capability. DVR has been controlled using optimized proportional and integral (PI) gains integrated with gradient adaptive variable learning rate least mean square control algorithm. Adaptiveness of variable step-size in LMS makes the control robust in case of dynamics in the system, which assures better performance. Also, the other major contribution of this article is the implementation of optimization-based self-tuning PI gains in the proposed control. The evaluation of optimizer in estimating the PI gains is presented in terms of the response of dc-link voltage DVR. The simulation work of proposed control algorithms on DVR has been done and satisfactory results are found. For the experimental validation, d-SPACE made Micro Lab Box is used as control processor, and both dynamic and steady-state results are discussed for its effectiveness.

A Modified Series Voltage Controller for Power Conditioning

A compensation method for mitigation of voltage related power quality problems with the use of Series Voltage Regulator well known as Series Active Power Filter or Dynamic Voltage Restorer is presented in this paper. The classical control algorithm used for series voltage regulator based on the Park transformation is modified by introducing a Selective Harmonic Filter at detection stage of source current in order to compensate harmonic frequencies which mainly affect power frequency voltages. The significant outcomes are sag restoration, reduction of total harmonic distortion and removal of transients from the supply voltage. Thus it makes possible to improve performance of series voltage controller as power conditioner to mitigate various voltage related power quality issues. The proposed approach is cost effective because same series voltage controller can be used as power conditioner by modifying control strategy used. Also it is possible to eliminate use of PI controller from control circuitry. The usefulness and robustness of the proposed mitigation strategy is confirmed by simulation studies. The presented series voltage controller has ability to mitigate the power quality issues arising due to charging of electric vehicles.

Phase Locked Loop Based on Third Order SSI for Compensation of Voltage-Related Power Quality Issues Using DVR

Application of dynamic voltage restorer (DVR) is extended to the compensation of distortions and imbalances in the grid voltage by applying phase locked loop based on the sinusoidal signal integrator of third order. For dealing the distortions and imbalances in voltage, a fundamental positive sequence component is required. The conventional PLLs fail to track grid voltage in case of distortions and imbalances in supply system. Under distorted or unbalanced grid voltage condition, the fundamental positive sequence components are to be extracted from third order sinusoidal signal integrator phase locked loop (TOSSI-PLL). This kind of extraction of grid angle from the distorted/unbalanced grid helps to improve the dynamic performance. The performance of DVR with TOSSI-based PLL under sag, swell, distortions and an imbalance has been demonstrated using MATLAB/Simulink and validated in real time through OP-5142 using FPGA-based XC3S5000 series processor.

Photovoltaic tied unified power quality conditioner topology based on a novel notch filter utilized control algorithm for power quality improvement

Nonlinear loads and grid side disturbances in the power distribution network cause harmonic rich currents and voltage perturbations such as voltage harmonics, voltage sags and voltage swells. The unified power quality conditioner (UPQC) with shunt inverter and series inverter are usually employed for elimination of current and voltage related power quality issues. However, elimination of voltage and current quality issues in a grid connected Photovoltaic (PV) system is essential. Therefore, PV integrated UPQC topology is proposed in this paper with a novel controller for power quality improvement. The control algorithm based on notch filter Phase Locked Loop (PLL) is utilized for proper phase detection and elimination of voltage and current disturbances. PV tied UPQC controller based on notch filter PLL has the capability to avoid multiple zero crossing during highly distorted grid voltage condition. Conventional control algorithms such as synchronous reference frame theory, unit vector controller based on traditional PLL are also analyzed for the control of PV tied UPQC. The proposed system is developed in Matlab/Simulink and the results obtained are evaluated to measure the performance. A real-time hardware prototype is developed using dSPACE processor. The obtained experimental results validate the efficiency of the proposed controller for PV tied UPQC.