Power Quality Related Problems Research Articles

Ladder broadband damping filters

RELEVANCE. The large proliferation of various nonlinear loads has led to serious power-quality related problems in power systems. THE PURPOSE. In this paper, we consider design procedure of broadband passive filters with flat frequency characteristics. METHODS. A general method for optimally design the arbitrary order broadband passive filters (BBF) is considered. The base structure of BBF has the form of resistively loaded reactive two-port. Conditions of low fundamental frequency loss and required filer selectivity have been determined. The BBF design procedure minimizes the grid total current distortion and takes into account the power system performance. RESULTS. New broadband passive filter scheme are proposed. Compensating performances of different BBF configurations are discussed. Case studies demonstrated that proposed scheme can filter characteristic and damp non-characteristic harmonic simultaneously. CONCLUSION. The results show that proposed broadband damping filters are the effective instrument for the power quality normalization in industrial power systems.

PV Grid-Connected Inverter With DC Voltage Regulation in CCM and VCM Operation to Reduce Switching Losses

In this paper, a photo-voltaic (PV) grid connected inverter (GCI) is employed for multi-functional control (i.e., real power flow control form PV panels, mitigation of current and voltage related power quality (PQ) problems) and the GCI input reference dc voltage is formulated as a function of GCI output currents for loss reduction during low currents through inverter switches. In the latest literature, PV GCI is used for mitigating current related PQ problems, and it is also used for mitigating minor voltage related PQ problems (voltage sag, voltage swell, and voltage imbalance). During voltage sag conditions, GCI output current is high enough to maintain rated voltage at the point of common coupling (PCC) and in this case the reference dc voltage requirement is high. But, during rated grid voltage condition, low power generation from PV, and minimum load condition keeping maximum dc voltage at the input of GCI leads to heavy burden on GCI switches. In the proposed method, in order to reduce losses in GCI, the input dc voltage of GCI is reduced during low GCI output current. The proposed method is validated with MATLAB simulation and hardware experiment by comparing data existing in literature with the proposed method.

Implementation of IoT-based energy monitoring and automatic power factor correction system

Energy monitoring facilitates quick access and helps to know the power utilization and normal and abnormal conditions. Nowadays, many applications and majorly industries face problems regarding power quality. In the power system, the power factor plays a vital role in power quality. The addition of capacitance overcomes the decay of the power factor and reduces the power loss. This paper aims to build an automatic power factor correction (APFC) system, which can monitor the energy consumption of a system and automatically improve its power factor. In the design, an open-source energy monitoring library has been implemented for accurate power calculations. This paper carried out the work of hardware experimentation of energy monitoring and automatic power factor correction using a capacitor bank with the association of Internet of Things (IoT) technology. Build a mobile application to more simply and comfortablely monitor power and correct automatically. The developed hardware model’s performance is validated with and without load conditions. The result proves that the designed Raspberry Pi-based energy monitoring and automatic power factor correction system outperforms to improve the power factor without human interaction by properly switching the capacitor bank. Hence, the power loss, penalty, and power quality-related problems were resolved based on the proposed approach. The proposed design is compact, simple, and easy to implement and aids in power system advancement.

The Improved Unified Power Quality Conditioner with the Modular Multilevel Converter for Power Quality Improvement

Nowadays, researchers focus on the modular multilevel converter (MMC), due to its modularity structure, effective sharing of voltages among the submodule switches, and betterment in the quality of the voltage and current waveforms. First, the conventional unified power quality conditioner is developed with two level voltage source converters connected back-to-back, which are proposed to mitigate both the voltage and current related power quality problems. Later, to improve the performances (voltage sag, swell, current harmonics, etc.) of the conventional method, multilevel inverters are used. In this paper, a modified unified power quality conditioner based on a modular multilevel converter is implemented to mitigate the voltage and current related power quality issues. The design of the MMC is very simple with a modular structure, and it also improves the performance of the system compared to the conventional methods. In this proposed topology, the voltage related compensation is implemented with a seven-level MMC, and the current compensation is achieved with a reduced four switch voltage source inverter. The developed system is simulated in the MATLAB platform, and results are validated by hardware implementation with a FPGA controller. It is observed that the developed system has less % of total harmonic distortion and reduction in voltage sag as per the prescribed IEEE 519–2014 standards and practices.

Harmonics Constrained Approach to Composite Power System Expansion Planning with Large-Scale Renewable Energy Sources

Renewable energy sources (RES) are becoming more attractive due to the global demand for the utilization of clean energy and their easy accessibility. The integration of renewable energy technologies into power systems has been made easy, such that RES can be incorporated into small distribution systems or power grids. This integration of RES has negative impacts on power quality, system reliability, and network security. This could affect the RES performance and causes power quality-related problems such as harmonics, voltage flickers, swell, and sag. This paper presents a generation and transmission expansion planning model with the integration of large-scale RES considering harmonic emissions constraints. This method uses a weighted sum approach to combine the multi-objective optimization problems, thereby minimizing the total costs, active power loss, and harmonic power loss. An analytical technique was developed to estimate and quantify the harmonic emissions from the RES components. The proposed AC mixed-integer non-linear optimization problem was solved using algebraic modeling language. The proposed model is demonstrated on non-distorted Garver’s test bus system and 48-bus of Nigeria’s power system. The results obtained from the sensitivity analysis can be used as a decision-making tool to determine the best approach to minimize harmonic emissions from RES integration into the grid.

Simulation of PEM fuel cell integrated DVR using SRF-ANFIS controller for power quality enhancement

Voltage related Power Quality (PQ) problems are attracting the eyes of researchers, as these cause huge loss in productivity and profitability for both utilities and consumers. Dynamic Voltage Restorer (DVR) is a well-known custom power device that provides an economical solution for the alleviation of power quality problems. Generally, battery energy storage is used as an input for DVR, but batteries are still bulky and costly and must be disposed once their chemicals are used, which limits the compensation capability of DVR. Nowadays, Fuel Cell (FC) technologies have attracted much attention owing to their high efficiencies and low emissions. This project aims to model and simulate Proton Exchange Membrane Fuel Cell (PEMFC) and is used as a DC input source for DVR. The suitable boost converter is designed and modelled to lift up the fuel cell output voltage suitable as DC link voltage for DVR. Adaptive Neuro Fuzzy Inference System (ANFIS) controller uses Synchronous Reference Frame Theory (SRF) algorithm to generate d and q axis components of reference signal for Voltage Source Converter (VSC) of DVR. This PEMFC DVR is verified for balanced and unbalanced voltage sag, swell, and harmonics using MATLAB/SIMULINK. A simulation result proves that this PEMFC DVR is capable of providing a technically advanced and economic solution for balanced and unbalanced voltage sag and swell. During compensation, the DVR DC input voltage is also preserved as constant, which enhances the compensation capability of DVR.

Online harmonic extraction and synchronization algorithm based control for unified power quality conditioner for microgrid systems

This manuscript proposes an Adaptive Linear Neural Network (ADALINE) based control for the unified power quality conditioner to protect the critical loads from voltage related power quality problems and mitigate the current related power quality problems produced by nonlinear loads. Due to parallel computing feature and simple algorithm, ADALINE is utilized widely in parameter estimation. In this manuscript, unified ADALINEs based current harmonic extractor for the shunt active power filter is utilized, and an ADALINE based control technique is utilized to produce reference voltages for load voltage compensation. Due to ADALINE control, the necessity of a phase locked loop and conventional filters are omitted, therefore, enabling the system to extract the fundamental components more accurately. Besides, the ability of self-regulating transition from islanded mode to grid-connected mode has ensured that uninterrupted power supply is provided to the critical loads. The system performance is validated through simulation results utilizing MATLAB-Simulink software considering several dynamic conditions, namely unbalanced grid voltage, self-regulating transition, and grid unavailability.

Mitigation of power quality issues using UPQC

Abstract Power quality has become major concern these days due to application of power electronic devices. Conventional equipment like passive filter, segregate series and shunt filters and synchronous condenser etc. have become inadequate to mitigate different power quality problems. Since, power quality mainly concerned with voltage quality and the current quality in the system. For voltage quality, series compensator is used and for current quality, shunt compensator is used. Further, when these two power quality problems are mitigated simultaneously, the device, which is used, called unified power quality conditioner (UPQC), in power distribution system. In this paper voltage related power quality problems such as (voltage sag, voltage swell, voltage and current distortion) are discussed and UPQC controller is simulated to mitigate these problems. There are different control techniques available for UPQC. Here one of them i.e., unit vector template generation (UVTG) is used to simulate UPQC controller. The considered system efficiently regulated the DC link voltage using properly tuned PI parameters. The proposed work is also validated using experimental results.

Compensation of voltage‐based power quality problems using sliding mode observer with optimised PI controller gains

This study discusses a control algorithm for dynamic voltage restorer (DVR) based on sliding mode observer (SMO) with an optimisation-based proportional integrator (PI) tuning to compensate the voltage related power quality problems. In this work, a three-phase VSC-based topology of DVR is selected with a self-supported capacitor. This DVR configuration using the proposed control algorithm has been used for mitigation of unbalance, sag, and swells in the supply voltage. The estimation of grid parameters in undesirable situations based on the exosystemic model are the advantages proposed control. New nature-inspired optimisation algorithm named as Harris hawks optimiser (HHO) has been applied to obtain the PI gains in the control algorithm to eliminate the time required for the tuning process. The main advantage of HHO is the avoidance of local minima and exploration and exploitation features of the algorithm. DVR system with a combination of SMO-based control algorithm along with HHO optimised PI controllers have been developed in MATLAB/Simulink and tested for above said voltage-based disturbances mitigation in the supply voltage.

Power factor correction and power quality improvement of supply grid with self-supported transformer-less DSTATCOM for different control strategies

This paper investigates the performance of transformer-less distribution static compensator (DSTATCOM) integrated at the side of the utility distribution system for four different control strategies, viz., unit template (UT) theory, synchronous reference frame (SRF) theory, instantaneous reactive power theory (IRPT) and power balance theory (PBT). The simulation models for the three-phase three-wire power system have been designed to achieve unity power factor with different loading conditions (balanced and unbalanced linear and nonlinear loads). The DC-link is self-supported, i.e., no energy storage element is used but a DC-link capacitor is used only. DSTATCOM fulfils almost all the objectives related to the current related power quality problems created by different types of load. Here, it eliminates the harmonics, compensates reactive power which reduces the burden on the grid, makes the grid power factor unity and eliminates the load unbalances. Here, steady-state and dynamic state analysis has been discussed and comparative results have been presented.

Power factor correction and power quality improvement of supply grid with self-supported transformer-less DSTATCOM for different control strategies

This paper investigates the performance of transformer-less distribution static compensator (DSTATCOM) integrated at the side of the utility distribution system for four different control strategies, viz., unit template (UT) theory, synchronous reference frame (SRF) theory, instantaneous reactive power theory (IRPT) and power balance theory (PBT). The simulation models for the three-phase three-wire power system have been designed to achieve unity power factor with different loading conditions (balanced and unbalanced linear and nonlinear loads). The DC-link is self-supported, i.e., no energy storage element is used but a DC-link capacitor is used only. DSTATCOM fulfils almost all the objectives related to the current related power quality problems created by different types of load. Here, it eliminates the harmonics, compensates reactive power which reduces the burden on the grid, makes the grid power factor unity and eliminates the load unbalances. Here, steady-state and dynamic state analysis has been discussed and comparative results have been presented.

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.

A Novel Non-Linear Control for Three-Phase Five-Level Cascaded H-Bridge Inverter Based Shunt Active Power Filter

Abstract Cascaded H-Bridge multilevel inverter (CHB-MLI) based shunt active power filter (SAPF) provides a cost-worthy and realistic solution for mitigating current related power quality problems in case of medium-voltage and high-power grid. Mitigation of current harmonic component, reactive power minimization and power factor correction depend on accuracy of control technique applied to the CHB-MLI based SAPF unit. Switching technique dynamics is not considered by most of the researchers while designing control techniques applied to SAPF unit and hence it is assumed linear in order to make system simpler. A limited amount of literature is available which considers the non-linearity of CHB-MLI switching pattern while designing control theory for MLI based SAPF. Therefore, a novel non-linear control is proposed in this paper to enhance system steady-state and dynamic performance. This non-linear control is based on dynamic mathematical modeling of five-level CHB-MLI tied SAPF. Stability of proposed control strategy applied to CHB-MLI based SAPF is rigorously checked by using Lyapunov’s direct method. Proportional-Integral controller is used for stabilizing DC-link voltages to its proper reference value. This proposed control exhibits excellent dynamic performance and compensation criteria in comparison to conventional control techniques available in the literature. The effectiveness of the proposed control theory is tested rigorously in MATLAB/Simulink and verified through hardware prototype under steady-state and transient operating conditions. Rigorous analysis from hardware and simulation results confirms that source current waveform is in compliance with IEEE-519 standard defined THD limit.

Improved Residential Distribution System Harmonic Compensation Scheme Using Power Electronics Interfaced DGs

Increased non-linear residential loads in today's distribution system is a concern due to the harmonics related power quality issues. The situation gets worsened by the harmonic resonance introduced by the installation of power factor correction (PFC) capacitor banks in the distribution network. At the same time, more and more renewable energy-based distributed generation (DG) units are being installed in the residential area. These DG systems can be used as an effective way to mitigate the harmonic related power quality problems introduced by the nonlinear residential loads. In literature, very limited work has been done to identify harmonic compensation priorities that should be assigned to different DGs operating at different locations of the distribution system for improved compensation performance. This issue is addressed in this paper. A selective harmonic compensation scheme based on modal analysis is developed to assign compensation priorities on DGs operating at different distribution system nodes for improved compensation performance. A modeled residential distribution system containing distribution components such as distribution line, PFC capacitors, transformers, and household appliances along with DG units is used to verify the improvement of compensation performance. Experimental verification of the proposed method is also provided.

Adaptive recursive inverse‐based control algorithm for shunt active power filter

A new adaptive control technique is proposed for a three-phase shunt active power filter (SAPF) in this study. The proposed control algorithm is based on recursive inverse theory which is used here to extract weighted values corresponding to fundamental active and reactive power components of load currents. This adaptive control algorithm possesses advantages over other control algorithms in terms of its reduced computational complexity, fast weight convergence and robust performance in distorted environment. The SAPF is used to mitigate current related power quality problems such as harmonics, reactive power and load unbalancing in both modes of power factor correction and voltage regulation. The performance of proposed control algorithm of SAPF is demonstrated through simulation results in Matlab/Simulink environment, which are validated with test results obtained on the developed experimental prototype of SAPF in the laboratory.

Power Quality Analysis and Power System Study in High Voltage Systems

This paper presents is to identify the causes for series reactor failures and to monitor and protect the 11 KV power system components and equipments from the harmonics and transients and other power quality related problems. Power quality is a major concern of our modern industries and other consumers. Poor quality of supply will affect the performance of customer equipment such as computers, microprocessors adjustable speed drives, power electronic devices, etc. and results in heavy financial losses to customers due to loss of production or breakdown in industries or loss of life in a hospital. The two major power quality disturbances are voltage sag and harmonic distortion. In the event of voltage sag, due to insufficient energy, equipments may malfunction or trip. Harmonics introduced by nonlinear loads can pollute the input supply to the sensitive equipments and cause the connected equipments to malfunction. In this paper, a Power Quality Provider is proposed and modeled by simulation with the help of external agencies meters.

Matrix Converter Based Unified Power Quality Conditioner (MUPQC) for Power Quality Improvement in a Utility

This study proposes a new approach of unified power quality conditioner which is made up of a matrix converter without energy storage devices to mitigate the current harmonics, voltage sags and swell. By connecting the matrix converter output terminals to the load side through series transformer and the input side of matrix converter is connected to the supply side with step up transformer. So a matrix converter injects the compensation voltage on the load-side, so it is possible to mitigate the voltage sag/swell problems, resulting in an efficient solution for mitigating voltage and current related power quality problems. Thus, the proposed topology can mitigate the voltage fluctuations and current harmonics without energy storage elements and the total harmonic distortion produced by the system also very low. It also reduced volume and cost, reduced capacitor power losses, together with higher reliability. The Space-Vector Modulation (SVM) is used to control the matrix converter. MATLAB/SIMULINK based simulation results are presented to validate the approach.

Modeling of the CIGRE Low Voltage Test Distribution Network and the Development of Appropriate Controllers

The fluctuating nature of some of the Distributed Generation (DG) sources can cause power quality related problems like power frequency oscillations, voltage fluctuations etc. In future, the DG penetration is expected to increase and hence this requires some control actions to deal with the power quality issues. The main focus of this paper is on development of controllers for a distribution system with different DG’s and especially development of a Photovoltaic (PV) controller using a Static Compensator (STATCOM) controller and on modeling of a Battery Storage System (BSS) also based on a STATCOM controller. The control system is tested in the distribution test network set up by CIGRE. The new approach of the PV controller is done in such a way that it can control AC and DC voltage of the PV converter during dynamic conditions. The battery controller is also developed in such a way that it can control its charge/discharge rate and also the reactive power flow through the lines in order to improve the power factor. Simulation results shows that the controllers are able achieve a good power quality in the test grid.

The investigation of dynamic performance of induction generator in different operational conditions and improving its behaviour using proper FACTS devices

The object of this paper is to study the possibility of using of SVC and STATCOM in order to improve dynamic performance of induction generator. Also, these two devices have been compared with each other. Induction generators have many advantages in small wind-hydro power plants. On the other hand arising some problems including controlling of voltage and frequency oscillation due to dynamic oscillation of load and also power quality related problems causes us to study these generators widely. In most studies, the performance of generator has been estimated just in continuous mode and by each one the method of designing only one FACTS device has been described. Although in most studies design details and definition of various parameters of these devices have been considered but the behavior of generator with each of these devices, however, and their advantages to each other in different conditions has not been investigated yet. In this paper among comparing the above mentioned devices and clarifying their advantages to each other we show that employing both tools has significant impact on the quality of the produced energy from generators especially self excited ones and this approach would be useful for improving their loading characteristics. Key words: Dynamic behavior, induction generator, FACTS.

Integration of embedded generation in local grid using STATCOM

The renewable sources of energy are being connected to the local distribution system/local grid leading to embedded generation. As these sources are intermittent in nature, they impose technical challenges in the power system operation which include power quality related problems of local grid. The performance of the system has to be evaluated while connecting these sources to the local distribution system/micro grid. In this paper, the application of STATCOM-based power quality conditioner for improving the performance of wind driven induction generator embedded to the local grid have been discussed. The modelling, control and analysis of the proposed STATCOM-based power quality conditioner have been given. The MATLAB Simulink-based system model has been used for the performance evaluation while connection of wind-driven induction generator to the local grid, its variable speed operation and unbalanced supply system. The STATCOM-based power quality conditioner has been found effective for the power quality improvement of the local grid.