A Novel Intelligent Neural Network Techniques of UPQC with Integrated Solar PV System for Power Quality Enhancement

A Novel, Intelligent control of a Unified Power Quality Conditioner (UPQC), coupled with a Photovoltaic (PV) system, is proposed in this work. It enhances the decarbonizes clean energy generation and maintains Power Quality (PQ) to the grid. In PV integrated UPQC, Crow Search Algorithm (CSA) assisted Perturb and Observation (P&O) Maximum Power Point Tracking (MPPT) technique. A d-q theory-based control is employed with the assistance of a Proportional Integral (PI) controller for controlling the working of UPQC and maintaining the power quality. The dynamic working of the PV-based UPQC is evaluated based on simulation outcomes attained from MATLAB

Mitigation of Power Quality Problems Using Custom Power Devices: A Review

Electrical power quality (EPQ) in distribution systems is a critical issue for commercial, industrial and residential applications. The new concept of advanced power electronic based Custom Power Devices (CPDs) mainly distributed static synchronous compensator (D-STATCOM), dynamic voltage restorer (DVR) and unified power quality conditioner (UPQC) have been developed due to lacking the performance of traditional compensating devices to minimize power quality disturbances. This paper presents a comprehensive review on D-STATCOM, DVR and UPQC to solve the electrical power quality problems of the distribution networks. This is intended to present a broad overview of the various possible DSTATCOM, DVR and UPQC configurations for single-phase (two wire) and three-phase (three-wire and four-wire) networks and control strategies for the compensation of various power quality disturbances. Apart from this, comprehensive explanation, comparison, and discussion on D-STATCOM, DVR, and UPQC are presented. This paper is aimed to explore a broad prospective on the status of D-STATCOMs, DVRs, and UPQCs to researchers, engineers and the community dealing with the power quality enhancement. A classified list of some latest research publications on the topic is also appended for a quick reference

New topology of shunt hybrid power filter for harmonic mitigation and re-utilization of harmonic filter current as useful power

Power electronic appliances are recently used widely in industrial, commercial, and home sectors; these appliances include diode and thyristor rectifiers, and variable speed drive systems. When these appliances are connected to the grid, they generate harmonics in the current and voltage waveform which contributes to the degradation of the system efficiency and deterioration of the overall system performance due to an increase of effective peak value and also the rms current in some devices. Conventional passive power filters (PPF) for harmonic mitigation have inherent problems, while purely active power filters (APF) have the disadvantages of higher costs and ratings. Hybrid active filters (HPF) inherit the efficiency of PPFs and the improved performance of APFs, and thus, constitute a viable improved approach for harmonic compensation. An eight different HPF topology is composed of one APF and PPF in series or shunt or combination. Nevertheless, among the existing mitigation HPFs, the shunt LC HPF is the most effective against current harmonics problems due to its feasibility for harmonic current compensation. However, it cannot perform satisfactory dynamic reactive power compensation because reactive power varies from time to time. Furthermore, to have low impedances at high frequencies, the capacitor of this filter needs to be large which will be influenced seriously by the source inductor. In this study, a new topology of shunt RLC-HPF is introduced to improve the efficiency of current harmonic reduction and perform power factor (PF) correction through reactive power compensation via the provision of a low impedance path through the inductor (for low frequencies) and low impedance through the capacitor (for high frequencies).. The effectiveness of HPF is strictly dependent on how quickly and accurately the detection of reference harmonic current, DC-link capacitor voltage regulation, and current control is achieved. The shunt HPF was designed based on synchronous reference frame strategy (SRF) and self-tuning filter (STF) to develop the operation of the filter under non-ideal (unbalanced and/or distorted) source voltage conditions. As for its controller, switching signals to drive the voltage source inverter (VSI) of the shunt APF adaptive hysteresis current controller (AHCC) are used. Also, proportional-integral (PI) and back propagation neural network (BPNN) controllers are developed to maintain a constant voltage across the DC-link capacitor so that the shunt APF can precisely inject the desired referred currents back into the harmonic power system. The shunt HPF performance is validated for all possible conditions of source and load by simulation using MATLAB/ Simulink environment. The simulation results obtained by the STF -SRF strategy with BPNN controller showed excellent achievement when compared to SRF with PI controller in the mitigation of current harmonics, PF enhancement, and DC voltage regulation. As a result, the minimum total harmonic distortion (THD) values of the source current recorded clear advantages of the STF-SRF strategy (1.8 %) over the existing SRF strategy (10 %), especially in dealing with non-ideal source voltage conditions. Furthermore, the encouraging findings have led to the correction of the PF to 0.999 using STF-SRF in contrast to 0.842 with the SRF strategy. Moreover, the DC-link capacitor voltage was properly regulated and maintained at the respective desired values under all cases with the BPNN controller, while the PI controller failed to be regulated. Ultimately, the main aim of the new HPF topology is the improvement of PF and reducing harmonic current, as well as re-utilization of the extracted harmonic filter current via conversion to useful power to feed the RL load within the limitation of the IEEE-519-2014 standards

Power quality improvement in low voltage distribution network utilizing improved unified power quality conditioner.

Doctoral Degree. University of KwaZulu-Natal, Durban.The upgrade of the power system, network, and as it attained some complexity level, the voltage related problems and power loss has become frequently pronounced. The power quality challenges load at extreme end of the feeder like voltage sag and swell, and power loss at load centre due to peak load as not received adequate attention. Therefore, this research proposes a Power Angle Control PAC approach for enhancing voltage profile and mitigating voltage sag, voltage swell, and reduced power loss in low voltage radial distribution system (RDS). The amelioration of voltage sag, voltage swell, weak voltage profile, and power loss with a capable power electronics-based power controller device known as Improve Unified Power Quality Conditioner I-UPQC was conceived. Also, the same controller was optimally implemented using hybrid of genetic algorithm and improved particle swarm optimization GA-IPSO in RDS to mitigate the voltage issues, and power loss experienced at peak loading. A new control design-model of Power Angle Control (PAC) of the UPQC has been designed and established using direct, quadrature, and zero components dq0 and proportional integral (PI) controller method. The simulation was implemented in MATLAB/Simulink environment. The results obtained at steady-state condition and when the new I-UPQC was connected show that series inverter can participate actively in ameliorating in the process of mitigating sag and swell by maintaining a PAC of 25% improvement. It was observed that power loss reduced from 1.7% to 1.5% and the feeder is within the standard limit of ±5%. Furthermore, the interconnection of I-UPQC with photovoltaic solar power through the DC link shows a better voltage profile while the load voltage within the allowable range of ±5% all through the disturbance and power loss reduction is 1.3%. Lastly, results obtained by optimal allocation of I-UPQC in RDS using analytical and GA-IPSO show that reactive power injection improved the voltage related issues from 0.952 to 0.9989 p.u., and power loss was further reduced to 1.2% from 3.4%. Also, the minimum bus voltage profile, voltage sag, and power loss are within statutory limits of ±5 % and less than 2 %, respectively. The major contributions of this research are the reduction of sag impact and power loss on the sensitive load in RDS feeder.Publications on page iii

Optimal Designing Grid-Connected PV Systems

Photovoltaic systems, direct conversion of solar energy to electrical energy, are produced in the form of DC power by photovoltaic arrays bathed in sunlight and converted into AC power through an inverter system, which is more convenient to use. There are two main paradigms for optimal designing of photovoltaic systems. First, the system can be designed such that the generated power and the loads, that is, the consumed power, match. A second way to design a photovoltaic system is to base the design on economics, as pinpointed in the following. Photovoltaic grid connected through shunt active filter by considering maximum power point tracking for these systems is known as the optimal design. This chapter is organized as follows: First, we discuss an overview of grid-connected photovoltaic systems. After that, we take a more detailed look on grid-connected photovoltaic system via active filter; in this section, we explain the modeling of photovoltaic panel and shunt active filter. In the next section, we learn different maximum power point tracking methods and also learn how to design DC link as a common bus of shunt active filter and photovoltaic system. Finally, MATLAB/Simulink simulations verify the performance of the proposed model performance

Power Quality Improvement using a New DPC Switching Table for a Three-Phase SAPF

This research focuses on the analysis and design of robust direct power control (DPC) for a shunt active power filter (SAPF). The study proposes a novel switching table design based on an analysis of the impact of inverter switching vectors on the derivatives of instantaneous reactive and active powers. The goal is to reduce the number of commutations by eliminating null vectors while maintaining the desired DC-bus voltage using a PI regulator-based anti windup technique. Additionally, a robust PLL structure-based band pass multivariate filter (BPMVF) is utilized to enhance the network voltage. The research demonstrates the effectiveness of the suggested power control through extensive simulation results, showing high performance in both transient and steady-state conditions. The proposed approach offers the advantages of sinusoidal network current, and unitary power factor, and eliminates the need for current regulators and coordinate transformations or PWM generators. Further research directions could explore the practical implementation and real-world performance of this technique in power systems

Adaptive hysteresis based fuzzy controlled shunt active power filter for mitigation of harmonics

Active filters are widely employed in distribution system to reduce the harmonics produced by non-linear loads result in voltage distortion and leads to various power quality problems. In this work the simulation study of a Adaptive hysteresis based fuzzy logic controlled shunt active power filter capable of reducing the total harmonic distortion is presented. The advantage of fuzzy control is that it is based on a linguistic description and does not require a mathematical model of the system and it can adapt its gain according to the changes in load. The instantaneous p-q theory is used for calculating the compensating current. Fuzzy-adaptive hysteresis band technique is adopted for the current control to derive the switching signals for the voltage source inverter. The fuzzy-adaptive hysteresis band current controller changes the hysteresis bandwidth according to the supply voltage and slope of the reference compensator current wave. A fuzzy logic-based controller is developed to control the voltage of the DC Capacitor. This work presents and compares the performance of the fuzzy-adaptive controller with a conventional fuzzy and PI controller under constant load. The total Harmonic Distortion, Individual harmonic content with respect to % of fundamental in Supply current, source voltage have been analyzed. Various simulation results are presented. And also the performance of two current control techniques namely adaptive hysteresis current control and fixed hysteresis control techniques are compared with respect to average switching frequency. A neural network control method for regulating the DC Voltage across the capacitor connected to the inverter for harmonic suppression is proposed. The THD of the source current after compensation is well below 5%, the harmonic limit imposed by the IEEE-519 standard

Mitigating unbalance using distributed network reconfiguration techniques in distributed power generation grids with services for electric vehicles: A review

© 2019 Elsevier Ltd With rapid movement to combat climate change by reducing greenhouse gases, there is an increasing trend to use more electric vehicles (EVs) and renewable energy sources (RES). With more EVs integration into electricity grid, this raises many challenges for the distribution service operators (DSOs) to integrate such RES-based, distributed generation (DG) and EV-like distributed loads into distribution grids. Effective management of distribution network imbalance is one of the challenges. The distribution network reconfiguration (DNR) techniques are promising to address the issue of imbalance along with other techniques such as the optimal distributed generation placement and allocation (OPDGA) method. This paper presents a systematic and thorough review of DNR techniques for mitigating unbalance of distribution networks, based on papers published in peer-reviewed journals in the last three decades. It puts more focus on how the DNR techniques have been used to manage network imbalance due to distributed loads and DG units. To the best of our knowledge, this is the first attempt to review the research works in the field using DNR techniques to mitigate unbalanced distribution networks. Therefore, this paper will serve as a prime source of the guidance for mitigating network imbalance using the DNR techniques to the new researchers in this field