Voltage Quality Issues Research Articles

Per-Phase Unsymmetrical Adaptive Derivative Optimized Droop for Mitigating Voltage Quality Issues of Unbalanced Islanded Microgrids

Per-Phase Unsymmetrical Adaptive Derivative Optimized Droop for Mitigating Voltage Quality Issues of Unbalanced Islanded Microgrids

Review on various voltage stability issues in AC distribution network

With the rapidly depleting natural energy resources and increasing population worldwide, the calls for more energy demand have risen globally. In this vein, the world is transitioning from traditional to renewable energy sources (RES) to meet the required demands. However, the (RES), due to its variable nature, has voltage stability and power quality issues that need to get minimized to enhance the reliability of the (RES) system. This paper reviews the voltage stability and quality issues in the AC distribution system based on renewable energy sources (RES). Initially the renewable energy sources and problems associated with renewable energy sources are discussed. This article gives an overview of voltage control strategies based on local as well as communication-based phenomenon for distribution networks. In this review a hybrid solar photovoltaic and wind system is used to generate the power of 3-5 kW. A voltage controller topology is suggested using MATLAB/Simulink for enhancing voltage stability of the system. It is suggested that a voltage stability controller can be designed using recommended topology by using Arduino with pulse width modulation technique. Thus, by measuring and correcting real-time voltage instability values of the system, the system can be made more reliably secure, efficient, and stable than the previously proposed renewable AC distribution systems.

Power quality improvement in distributed generation system using intelligent control methods

Hybrid <span>electric power generation and its integration with the grid to supply consumer demand is main focus of this paper. The use of nonlinear load and advanced power electronic equipment-based devices at the consumer end introduces power quality issues in the power system network in terms of voltage and current. This paper explains the design of a control algorithm for a unified power quality conditioner used for mitigating both voltage and current-based power quality issues. The dynamic voltage restorer of unified power quality controller (UPQC) is designed with a unit vector control algorithm and the distribution static synchronous compensator (DSTATCOM) is designed with fuzzy logic and adaptive network-based fuzzy inference system based instantaneous reactive power theory control algorithm. The simulation model built using the MATLAB platform includes a three-phase voltage source along with hybrid electric power generation connected to linear and non-linear loads operating under different conditions. The result is analyzed in terms of voltage and current total harmonic distortion compared with IEEE 512 power quality standards and power factor improvement. The paper shows the adaptive neuro-fuzzy inference systems (ANFIS)-based control algorithm gives better results in terms of total harmonic distortion (THD) compared to the fuzzy-based control algorithm. The power factor is improved using ANFIS-based controller proving the efficiency of the controller</span>.

Collaborative Distributed Optimal Control of Pure and Hybrid Active Power Filters in Active Distribution Network

The high penetration of power electronics in the active distribution network (ADN) induces system-level voltage quality issues. Conventionally, pure and hybrid active power filters (APF/HAPF) have been adopted in ADN for voltage quality improvement. However, each APF/HAPF can only compensate for local voltage quality issues due to a lack of coordination. This paper proposes a collaborative distributed optimal control (CoDOC) of APFs/HAPFs for ADN system-level voltage quality improvement. First, the operational characteristic of APF/HAPF is discussed, which formulates the APF/HAPF constraints. Then, the objective functions, harmonic power flow equations, and APF/HAPF operational constraints are proposed to formulate the proposed CoDOC as a convex problem. Moreover, a primal-dual subgradient (PDS) based optimization algorithm is proposed to solve the CoDOC problem in a distributed manner. The practical application aspects of the proposed CoDOC are also studied and discussed. Finally, the proposed CoDOC is verified by case studies compared to other representative ADN-level control methods.

Power quality enhancement by using Z-DVR based series voltage compensation with black widow optimization technique

In distribution system, voltage quality issues are the most concerning disturbances influencing the power quality (PQ). As a result, to alleviate this PQ concerns such as sag, swell, fluctuation, interruption, and harmonics on the sensitive load, the series voltage compensator dynamic voltage restorer (DVR) is utilized. Furthermore, a Z-source inverter (ZSI) based DVR is proposed in this paper to improve the power system's voltage restoration properties. To compensate the voltage concerns which is occurs in passive and transmission components, the 3-φ Z-DVR inverter with proportional integral derivative (PID) controller tuned by black widow optimization (BWO). By short circuiting the legs of inverter in the ZSI, prepare the possibility of buck and boost in voltage and utilize the LC impedance grid which incorporated power source to inverter circuit. In addition, to obtain the injecting voltage, PID control scheme for ZSI based DVR is proposed in this paper. The proposed modelling and simulation of DVR is implemented in MATLAB/Simulink tool and the outcomes are analyzed. Furthermore, reduction in voltage concerns, and total harmonics distribution (THD) with BWO tuned PID controller is superior which is 1.01% when compared with existing methods such as Harris Hawks optimization (HHO) based PID, genetic algorithm (GA) based PID controller.

Modified Adaptive Filter Based UPQC for Battery Supported Hydro Driven PMSG System

The standalone three phase system for power quality improvement of both the load side voltages as well as the currents of the machine terminal is presented in this paper. This standalone system consists of a three-phase permanent magnet synchronous generator (PMSG) driven by governor-less hydro turbine as a three-phase source feeding the sensitive/non-linear/linear loads, connected via a unified power quality conditioner (UPQC). The UPQC consists of a back-to-back connected voltage source converters (VSCs) sharing a common DC bus. The series compensator of the UPQC is used to eliminate voltage power quality (PQ) and to maintain the sinusoidal, balanced, and constant amplitude voltages at load terminals irrespective of any variation in the system. Moreover, the current quality such as reactive power compensation, harmonics elimination, etc. are provided by the shunt compensator of the UPQC, simultaneously while improving voltage quality issues. In addition, the efficiency of the overall system is significantly improved by running the generator below its rated voltage and reduces the losses by operating at unity pf. The system frequency and the generated voltage magnitudes are maintained during any load fluctuation or imbalance loading. The model of the UPQC based hydro turbine driven PMSG system is developed in the Simulink-MATLAB environment, and its results are presented for analysis. The validation of the system is also done on the hardware prototype, and it performs effectively for the voltage and current PQ enhancement simultaneously. It significantly improves the PQs at the generator terminals and ensures to adhere the IEC-61727 and the IEEE-519 standards even with either balanced or unbalanced loads.

Hybrid control mechanism-based DVR for mitigation of voltage sag and swell in solar PV-based IEEE 33 bus system

<p><span lang="EN-US">The power quality issues are raised due to sag/swell, which affects the overall performance of the grid-connected system. This study introduces the hybrid control mechanism based on a dynamic voltage restorer (DVR) to mitigate the sag and swell issues in the solar PV-based IEEE 33 bus system. The hybrid controller improves the dynamic performance and boosts the overall efficiency of the DVR system. The proposed work is also used to address the distribution system's voltage quality issues with minimal energy drawn out from the utility grid and effectively use solar energy. The sag and swell are introduced at the grid side and compensated at the load side by injecting DVR voltage. The proportional-integral (PI) controller followed by the fuzzy logic controller (FLC) is used to create the hybrid control mechanism for DVR. In this work, the solar PV system with DVR system is connected to the 29<sup>th </sup>location in the IEEE 33 bus system for performance realization. The hybrid control mechanism-based DVR provides 1.06% and 1.05% total harmonic distortion (THD) at sag and swell conditions for load voltage. The proposed work meets the IEEE 519 standards in terms of THD calculation. The proposed design compares with existing work and shows better THD reduction for load voltages.</span></p>

Analysis of Electric Vehicles Battery Ageing Associated to Smart Charging Controls

EVs smart charging controls emerge as a possibility to overcome voltage quality issues caused by the increasing penetration of EVs in LV networks. However, solving voltage issues implies that EV chargers must deal with reactive power provision, inducing an extra AC ripple in the battery that influences the EV battery lifespan. Four decentralized smart charging controls have been analyzed, modelled and implemented together with a commercial EV charger model and EV battery model that includes both runtime and ageing behavior. Results show that solving voltage issues with EV smart charging controls can lead to a temperature increment in the battery that influences the EV battery lifespan. Nevertheless, this situation can be effectively overcome by minor modifications in the EV charger or in the EV battery cooling system.

Enhancing voltage regulation using 5‐level TCHB based DVR in radial secondary distribution feeder system

SummaryThe voltage quality issues shows the significant effect on the performance of radial secondary distribution feeder. This paper aims to enhance the voltage regulation of radial secondary distribution feeder system using 5‐level TCHB inverter based dynamic voltage restorer. Series voltage drop is the major factor causes poor voltage regulation. A 5‐level TCHB inverter based DVR is used to inject the same amount of voltage dropped by series impedance. The DVR injects voltage with proper magnitude, phase and frequency with the proposed single phase PLL based SRF control circuitry. This enhances the voltage regulation by maintaining the load voltage at its rated value. Both the simulation and hardware results shows the enhancement of voltage regulation with mitigation using DVR.

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.

Comparative analysis of dual second-order generalized integrator-phase locked loop based series hybrid filter and static synchronous compensator for load voltage compensation and power quality improvement with grid synchronization in islanded microgrid

PurposeThe purpose of this study is to eliminate voltage harmonics and instantly measure the positive sequence fundamental voltage during unbalanced grid conditions, the dual second-order generalized integrator-phase locked loop used in series hybrid filter structures is often used in grid synchronisation in three-phase networks. The preferred series active hybrid power filter simultaneously compensates for voltage balancing and current harmonics generated by non-linear loads.Design/methodology/approachThis paper examines the use of renewable energy–based microgrid (MG) to support linear and non-linear loads. It is capable of synchronising with both the utility and the diesel generator unit. Power is transferred from the grid throughout a stable grid situation with minimum renewable energy generation and maximum load demand. It synchronises with diesel generator set to supply the load and form an AC MG during outages and minimum renewable power generation. In islanded and grid-connected mode, the voltage and power quality issues of the MG are controlled by static synchronous compensator and series hybrid filter.FindingsBecause of the presence of non-linear loads, reactive loads in the distribution system and the injection of wind power into the grid integrated system result power quality issues like current harmonics, voltage fluctuations, reactive power demand, etc.Originality/valueThe voltage at the load (linear and non-linear) is regulated, and the power factor and total harmonic distortions were improved with the help of the series hybrid filter.

Mitigation of Reactive Power and Harmonics in a Case of Industrial Customer

In most industrial plants, power quality is a major issue which hinders productivity and efficiency of the plants due to the use of semiconductor based loads and non-linear loads. As a result, to address the power quality problems in these industries, specialized power devices such as the Unified Power Quality Conditioner (UPQC), can be installed at the customer's location to resolve practically all power quality issues. UPQC consist of a series of active power filters (APF) which mitigate voltage quality issues and shunt active power filters which are used to reduce current quality issues, like harmonics and reactive power burdens. This paper, therefore presents an investigation and assessment of the power quality problems associated with Bahir Dar Textile Share Company. This was achieved by examining the voltage and current harmonic levels of various types of loads using PI and fuzzy logic controllers by measuring the level of total harmonic distortion (THD) with and without the insertion of the UPQC. The novelty of this paper is the implementation of the controller based customized UPQC for power factor and reactive power compensation. It was observed that by designing the system without and with UPQC, the results of the FFT analysis show that the fuzzy logic controller (FLC) reduced the harmonics level of the load voltage and current by 1.10% and 2.14% respectively. Generally, harmonics was alleviated by 90%, reactive power was reduced by 20%, and power factor was improved by 33%. Hence, the proposed UPQC is capable of holding the voltage and current harmonics levels within the acceptable limit, which satisfies the standards imposed by IEEE 519-1995.

IoT-based Communication Techniques of PVs Random Settlement in Residential Feeder

Whenever the additional random 1-5 kW rating and location photovoltaics (PVs) are connected into the residential feeder, the voltage profiles of the feeder become unbalanced. Besides the various load at the customer side has already imbalanced the feeder, the installed single-phase rooftop PVs do the same thing. They caused the power quality issues, namely voltage magnitude and angle, frequency, active and reactive powers become expressively recognized. Since the ancient electric utility infrastructure from power plants to customer side is now disrupting by the added settlement of several utility devices, the power quality issues have raisin significantly. This paper aims to implement the concept of several internets of things (IoT) technologies into the electric and communication infrastructures as they are able to virtuously cycle, enable, amplify and reinforce the utility development. To improve the imbalanced voltage and other power quality issues, this concept applied to the existed voltage regulation technique (VRT). The results show that the concept of IoT-based communication is successfully implemented if both the devices and technologies properly selected and designed. Additionally, the classification of communication layers, then the coordination of sensors, actuators, and meters along the residential feeder need to be considered as well.

IoT-based Communication Techniques of PVs Random Settlement in Residential Feeder

Whenever the additional random 1-5 kW rating and location photovoltaics (PVs) are connected into the residential feeder, the voltage profiles of the feeder become unbalanced. Besides the various load at the customer side has already imbalanced the feeder, the installed single-phase rooftop PVs do the same thing. They caused the power quality issues, namely voltage magnitude and angle, frequency, active and reactive powers become expressively recognized. Since the ancient electric utility infrastructure from power plants to customer side is now disrupting by the added settlement of several utility devices, the power quality issues have raisin significantly. This paper aims to implement the concept of several internets of things (IoT) technologies into the electric and communication infrastructures as they are able to virtuously cycle, enable, amplify and reinforce the utility development. To improve the imbalanced voltage and other power quality issues, this concept applied to the existed voltage regulation technique (VRT). The results show that the concept of IoT-based communication is successfully implemented if both the devices and technologies properly selected and designed. Additionally, the classification of communication layers, then the coordination of sensors, actuators, and meters along the residential feeder need to be considered as well.

Unsupervised detection and open-set classification of fast-ramped flexibility activation events

The continuous electrification of the mobility and heating sectors adds much-needed flexibility to the power system. However, flexibility utilization also introduces new challenges to distribution system operators (DSOs), who need mechanisms to supervise flexibility activations and monitor their effect on distribution network operation. Flexibility activations can be broadly categorized to those originating from electricity markets and those initiated by the DSO to avoid constraint violations. Coinciding electricity market driven flexibility activations may cause voltage quality or temporary overloading issues, and the failure of flexibility activations initiated by the DSO might leave critical grid states unresolved. This work proposes a novel data processing pipeline for automated real-time identification of fast-ramped flexibility activation events. Its practical value is twofold: (i) potentially critical flexibility activations originating from electricity markets can be detected by the DSO at an early stage, and (ii) successful activation of DSO-requested flexibility can be verified by the operator. In both cases the increased awareness would allow the DSO to take counteractions to avoid potentially critical grid situations. The proposed pipeline combines techniques from unsupervised detection and open-set classification. For both building blocks feasibility is systematically evaluated and proofed on real load and flexibility activation data.

Analysis of Traditional and Alternative Methods for Solving Voltage Problems in Low Voltage Grids: An Estonian Case Study

Smart Cities can benefit from existing municipal low voltage (LV) distribution grids by supporting public services with permanent power supply and providing grid connection points to distributed generators (DG). The increased integration of DGs and inverter based non-linear loads increases voltage quality issues, thus the cost-efficient assurance of voltage quality in LV grids with long radial lines is of increasing importance for the operators of municipal electricity distribution systems. Conventional methods for mitigating voltage quality issues (e.g., power line renovation) might not be optimal solutions either technologically or economically. Existing studies do not address all relevant issues related to the assurance of required voltage quality in such LV grids. This paper provides an overview of the applicability and rationality of traditional as well as alternative methods to solve voltage problems in LV grids. The authors use DIgSILENT PowerFactory software to simulate the performance of voltage stabilisers under different conditions. The authors propose a robust method for the classification of LV feeders and provide recommendations on how to resolve voltage quality problems, with the help of different power quality improvement devices, where the traditional methods of upgrading to medium voltage and grid reinforcement are economically infeasible. Based on our results, recommendations for mitigating voltage quality problems in LV distribution grids with radial lines of different lengths are given.

Novel MAF-Fuzzy Based IR-SRF Controller for DVR to Improve PQ Under Dynamic Weak Grid Conditions

This paper presents the development of advanced adaptive controller for dynamic voltage restorer (DVR) to regulate the power quality connected to a distribution system. Various voltage quality issues have been generated as distorted grid conditions are responsible for abnormal operation of the consumer electronics and domestic household appliances. Therefore dynamic voltage restorer (DVR) is employed for elimination of voltage quality issues in the distribution lines. To improve the performance and efficiency of DVR, an improved robust SRF (IR-SRF) controller has been developed in this paper for the mitigation of voltage quality issues under weak grid conditions. In the developed IR-SRF controller, moving average filter (MAF) has been utilized for better extraction of ripples from the sensed voltage. For better grid voltage signal synchronization with the proposed controller under highly dynamic condition, an enhanced Phase Locked Loop (PLL) scheme has been utilized instead of conventional PLL. For the regulation of DC link voltage under dynamic environmental conditions, MAF based fuzzy tuned PI controller has been utilized with the ability to adapt the situation. The developed controller has been simulated and results for various grid voltage conditions have been analyzed. The obtained simulation results are compared with conventional control algorithm to validate the efficacy. The efficiency of the proposed controller has been validated using the experimental results.

WILL THE SPOT-PRICE-BASED DEMAND RESPONSE OVERLOAD THE DISTRIBUTION NETWORK?

Flexibility demand increases in the electric power system especially because of the weather and time dependent variation of renewable electricity production. An existing flexibility source is electricity spot-price-oriented load control that is already possible for a significant number of end-users. New load control automation systems enable control of households heating loads so that residents may not recognise the control activities. In the countries where significant amount of residential heating is based on electricity spot-price-based demand response can be a valid scenario if the electricity end-users are willing to control their loads based on electricity prices. A drawback of this phenomena is that spot-price-based load control creates a synchronous signal that cumulates loads to same moment. From distribution system operator's (DSO) point of view the synchronised load control signal is a threat. It may cause overloading of network components and voltage quality issues if considerable amount of electricity users adapts the spot-price-based control. The paper indicates that the electric heating systems has potential to increase the loading of electricity distribution systems considerably, but the restrictions in end-user's flexibility and spot price variation may prevent efficiently arising of problems in electricity distribution in Finnish environment.

Perfprmance Analysis on Power Flow of a Three-Feeder/Multi-Bus Distribution System Using Gupqc

Power flow in any distribution system either it is multi-bus or three feeders explain by a Generalized Unified Power Quality Conditioner i.e. GUPQC.On the one side, that is DC side is connected with the common DC link capacitor which is also coupled consecutively through 3 voltage source converters. This is the simple block realization of GUPQC. This multi feeder is explained where one feeder is controlled by a parallel compensator and the next two feeders are controlled through the proposed series compensator. This technique i.e. GUPQC makes the feeder distribution free from harmonic and voltage-current compensation etc randomly. Also, it can improve the quality of supply power given to another consumer. A vast and huge study of Simulation is helped to how MATLAB/SIMULINK is used for making this type of GUPQC. Disrupted Voltage, current, and power quality issues can be easily improved in this technique.

Applications of optimization models for electricity distribution networks

AbstractIncreased penetration of low‐carbon technologies, such as residential photovoltaic systems, electric vehicles, and batteries, can potentially cause voltage quality issues in distribution networks. Active distribution networks adopt control schemes where these assets are actively managed to prevent potential issues, increasing the network utilization. Mathematical optimization is a key technology in enabling such applications, either directly as the underlying solution, or for benchmarking effectiveness. As networks are operated closer to their engineering limits, models representing distribution network physics become increasingly important. This article reviews how distribution networks are modeled with varying degrees of detail in the context of optimization problems. It goes on to catalog the applications that use such models, and ends with an overview of toolchains to implement them, to enable the transition from the passive to active management of the distribution system.This article is categorized under: Energy Systems Analysis > Systems and Infrastructure