Disturbances In Distribution System Research Articles

A multifunctional inverter power quality coordinated optimization strategy based on comprehensive evaluation

The large-scale integration of renewable energy sources and power electronic devices has led to increasingly dispersed and networked characteristics of power quality disturbances in distribution systems. Traditional control devices, limited by their fixed-point control, no longer meet the development needs of modern distribution systems. Considering the distribution and structural characteristics of the current new-type sources and loads, a multifunctional inverter power quality coordinated control strategy based on comprehensive evaluation is proposed. This strategy aims to achieve power quality coordinated control by utilizing optimal compensation capacity while the grid-connected inverter provides active power output. Firstly, the traditional ipiq power quality detection method is analyzed and improved to enable detection of harmonics, reactive power, and three-phase imbalance currents in single-phase systems or three-phase four-wire systems. Secondly, in the power quality assessment, a balanced algorithm is employed to obtain the comprehensive evaluation index of power quality, thereby improving the deficiencies of single-weight evaluation. Next, to ensure the grid-connected inverter achieves optimal power quality coordinated control with minimal compensation capacity, an optimization compensation function is established between compensation capacity and comprehensive power quality index. This function is optimized using non-dominated sorting genetic algorithm to enhance equipment utilization and system economy. Finally, the feasibility and effectiveness of the proposed method are validated through simulations, demonstrating the achievement of optimal capacity configuration for power quality coordinated control while ensuring active power output by the grid-connected inverter.

Use of Symmetrical Components in the Study of Electrical Disturbances in Distribution Systems with Charging Allocation for Electric Vehicles and Battery Banks

This paper presents a study of electric power distribution systems, which include battery banks and electric vehicle charging.Emphasis is placed to detect and distinguish voltage disturbances, conductor breaks, and other events that commonly occur in distribution systems. The research uses free license software ATPDraw™ to accurately model distribution systems and replicate voltage characteristics. The study investigates the ideal location of electric vehicle chargers, battery banks and electrical voltage meters in distribution systems. For this purpose, the General Algebraic Modeling System (GAMS) will be used, which provides high-level mathematical optimization capabilities to improve the observability of the system. Research will focus on possible mitigation to the problems these factors can cause in the power distribution system and explore strategies to minimize their negative effects. The discoveries will help improve the system performance, stability, and reliability of power distribution systems and support the integration of electric vehicles and energy storage.

Analisis Sistem Koordinasi Proteksi Over Current Relay (Ocr) Dan Ground Fault Relay (Gfr) Tegangan 20 Kv Bay Trafo Pada Gardu Induk Sanga-Sanga Kalimantan Timur

As a provider of electricity services, PLN is required to provide service and supply of electricity with good quality, continuity, improvement and efficiency. Disturbances in distribution systems are short circuit faults between phases or ground phase faults. To protect properly, proper coordination of relay settings is required. Among the equipment in the protection system used in distribution lines are overcurrent relays (OCR) and ground fault relays (GFR). In this study, an analysis of the OCR and GFR settings will be carried out on a 20 kV cubicle at the Sanga-Sanga Substation, East Kalimantan, with the help of the DigSILENT Power Factory 15.1.7 application with a disturbance simulation at 10% and 90% of the feeder length. Based on the analysis results, it is obtained that the short circuit results of 3 phases, 2 phases, and 1 phase to the ground have a value that is not much different from the calculation, while the OCR setting for the outgoing relay is 0.8 A on the secondary side. TMS is 0.083 seconds while the relay is on the incoming side of 20 kV 1 A and TMS of 0.198 seconds. The GFR setting for the outgoing relay is 0.06 A on the secondary side, and TMS is 0.1 seconds, and the relay on the incoming side is 20 kV 0.015 A and TMS is 0.26 seconds).

Five Level Flying-Capacitor Multilevel Converter Using Dynamic Voltage Restorer (DVR)

This paper deals with dynamic voltage restorer (DVR) controlled by a five-level flying-capacitor multi level converter. To decrease the power-quality disturbances in distribution system, such as voltage imbalances, harmonic voltages, and voltage sags. The organisation of this paper has been divided into three parts; the first one eliminates the modulation high-frequency harmonics using filter increase the transient response. The second one deal with the load voltage; and the third is flying capacitors charged with balanced voltages. The MATLAB simulation results effectively for five level flying capacitor multilevel converters charged with balanced voltage regulation.

Protection of Power Semiconductors in Inverters, using Fuses and their Coordination with the Protection Schemes of the Distribution System

The integration of Distributed Energy Resources (DER) implies an important challenge for the protection of the distribution network, due to the incorporation of devices with less capacity to withstand normal disturbances in distribution systems, particularly for overcurrents and overvoltages. The increasingly widespread use of power electronics, incorporated in rectifiers and inverters, which due to its weakness requires highspeed protection devices, complicates coordination with the traditional protection of distribution systems. Converters (rectifiers and inverters) require ultra-fast protection against high current faults, conditions that currently only meet high breaking capacity fuses. The response characteristics of these ultra-fast fuses, oblige the professional in charge of the protection of the distribution system to have a deep knowledge about the behavior of the power electronics in the face of overcurrents, and to know also how the fuses, through the selection of its rated values and characteristic curves protects it. Coordination of the rating values and characteristics of these fuses with their counterparts (when they exist) of traditional protection devices is the main objective of this article. Particular terms are explained in detail, such as fault current asymmetry and its effect on the coordination of protections, specific energy, etc. It is concluded that deep knowledge of the dissimilar characteristics of power electronics devices and the usual devices of distribution networks, with regard to their protections, are essential to obtain a maximum use of the traditional scheme with the addition of DER.

High impedance fault detection method based on the short‐time Fourier transform

A method to detect high impedance faults (HIFs) based on low-order harmonics is proposed. Short-time Fourier transform (STFT) is used to extract the main harmonic components of phase current, as magnitude and phase of the third harmonic and magnitude of the second and fifth harmonics, which are used to identify HIF occurrence. In addition, this study presents an analysis of the window length and type used in STFT and its suitability for the application. The method proposed is able to detect HIF occurrence at various points of the test system, as well as HIF happening on different soil surfaces. It is also capable of distinguishing HIF events from similar distribution system disturbances such as capacitor banks switching and feeder energising. Furthermore, it is effective when real HIF oscillography is applied, indicating its tolerance to typical noises present on real signals.

Multipurpose Compensation Scheme for Voltage Sag/Swell and Selective Harmonics Elimination in Distribution Systems

Voltage harmonics, sag, and swell are the most harmful disturbances in distribution systems. This paper introduces a novel effective controller method for simultaneous compensation of both voltage sag/swell and voltage harmonics by using multifunctional dynamic voltage restorer. In proposed controller method called FFT with integrated ISRF, ISRF detects the magnitudes of voltage sag/swell quickly and precisely, and FFT extracts the selective components of voltage harmonics very effectively. The proposed method integrates the superior properties of ISRF and FFT methods. FFT integrated ISRF is applied for the first time to provide the compensation of both sag/swell and selective harmonics together. The proposed system has ability to compensate symmetrical/asymmetrical sag/swell and symmetrical/asymmetrical selective harmonics which are 5th, 7th, 11th and 13th. The controlled system is modelled in PSCAD/EMDTC and compared with conventional methods. The performance results verify that the proposed method compensates voltage disturbances effectively in the system.

Reduction of Voltage Disturbances in Distribution System Using Neural Controller

Reduction of Voltage Disturbances in Distribution System Using Neural Controller

Real coded GA optimized fuzzy logic controlled PEMFC based Dynamic Voltage Restorer for reparation of voltage disturbances in distribution system

A voltage disturbance is one of the major power quality problems in electric power distribution system. Dynamic Voltage Restorer (DVR) is the effective device for compensation of voltage based power quality problems in distribution system. In this paper, the DVR is modelled to protect sensitive load from source side voltage disturbances under nonlinear load conditions. The real coded Genetic Algorithm (GA) optimized fuzzy logic controller is used to control both d and q components of the voltage. In addition to the compensation of harmonics in the load voltage, the proposed system is able to compensate both balanced and unbalanced voltage sag/swell in the load side. The effectiveness of the proposed DVR system under different types of fault condition is analyzed in MATLAB platform.

Interleaved Boost Converter Fed with PV for Induction Motor/Agricultural Applications

In present Electricity market Renewable Energy Sources (RES) are gaining much importance. The most common Renewable Energy Sources are Photo voltaic (PV), fuel cell (FC) and wind energy systems, out of these three PV systems PV system can implemented in most of the locations. Due to the power cuts and power disturbances in Distribution systems agriculture application is concentrated on PV based Energy system. The use of PV system is increasing day by day in agriculture application, due to their ease of control and flexibility. PV Electrification schemes also involves various subsidies in government national and international donors. Especially in Agriculture field by use of PV one can achieve higher subsidy. The output of PV system is low voltage DC to have high efficiency. The motors used in agriculture field are Induction Motors (IM) fed from Three phase AC supply, to boost the PV output we need a high voltage gain boost converter along with PWM inverter to Induction motor drive. Out of various DC-DC converter configurations interleaved boost converter is gaining much attention, due to its reduction in size and Electromagnetic Interference (EMI). In this work we are proposing a PV fed interleaved boost converter with PWM inverter for agriculture applications. The design process of interleaved boost converter is explain detail and compared with existing boost converter. A 10KW Power rating is choosing for the Induction motor drive and design calculations are carried out. A MATLAB/SIMULINK based model is developed for boost and interleaved boost converter and simulation results are presented, finally a scaled down hardware circuit design for interleaved boost converter and results are presented.

Voltage support in industrial distribution systems in presence of induction generator-based wind turbines and large motors

Industrial loads are usually composed of large induction motors (IM). These motors present a critical behavior under some circumstances, e.g. during starting and faults in the system. Currently, induction generator-based wind turbines are also connected to distribution systems. Essentially, these generators present the same behavior of large IM and, when directly connected to the system, their interaction can increase voltage sag levels or even lead the system to a voltage collapse. These generators, however, are usually provided with specific controls or power electronic-based equipment to comply with the voltage ride-through capability required by the grid codes. These resources, however, can be used to minimize the impact of large motors in the grid or even minimize their impact on voltage sags caused by faults in the system. In this context, this paper has the objective of analyzing the impact of different technologies used in induction generator-based wind turbines during disturbances in distribution systems in the presence of large IM. The analysis aims to clarify the potential benefit of wind turbine allocation at the demand side of an industrial power distribution system. Based on the results, an adapted control scheme, considering the control strategies currently available, is proposed for the grid side converter of the doubly fed induction generators to improve power quality.

Optimal placement and sizing of the storage supporting transmission and distribution networks

Developments of renewable energy resources imposes many uncertainties and variabilities in power grids. One of the best approaches to mitigate these stochastic disturbances is thought the use of Battery Energy Storage System (BESS). Besides application of the BESS such as decreasing the disturbances in distribution system, the grid frequency can be controlled in contingencies using the appropriate storage in transmission network to compensate the power shortage. Thus, the optimal siting and sizing of the BESS is important to have the minimum costs and losses. This paper describes a heuristic method to find the optimal location(s) and capacity of a multi-purpose BESS including transmission and distribution parts. In the transmission storage part, a sensitive analysis is performed using Complex-Valued Neural Networks (CVNN) and Time Domain Power Flow (TDPF) in order to detect the optimal BESS location(s). Additionally, running TDPF and Economic Dispatch (ED) leads to the optimal BESS size. In the distribution storage part, the optimal BESS size is calculated to perform distribution grid services such as peak load shaving and load curve smoothing. The proposed method has been applied to a real model (Maui island in Hawai'i -United States) to calculate the optimal results for both transmission and distribution sides.

Simulation of Power Quality Disturbances Using PSCAD

Power quality is becoming a concern in modern electrical network due to complexity of the system. To improve power quality, there needs to be analysis and research on complex power quality events systematically. Disturbances in distribution system, including sag/swell, transient, harmonic, voltage notch, and flicker that affect power quality are simulated in this research work. The comprehensive set of models are developed in PSCAD with minimum blocks and settings without compromising the essence of power quality events. This research work aims to introduce the power quality events to electrical engineering students, as well as reinforce understanding of power quality disturbances in distribution system through interactive simulation approach.

Public health and pipe breaks in water distribution systems: Analysis with internet search volume as a proxy

Drinking water distribution infrastructure has been identified as a factor in waterborne disease outbreaks and improved understanding of the public health risks associated with distribution system failures has been identified as a priority area for research. Pipe breaks may pose a risk, as their occurrence and repair can result in low or negative pressure, potentially allowing contamination of drinking water from adjacent soils. However, measuring this phenomenon is challenging because the most likely health impact is mild gastrointestinal (GI) illness, which is unlikely to result in a doctor or hospital visit. Here we present a novel method that uses data mining techniques and internet search volume to assess the relationship between pipe breaks and symptoms of GI illness in two U.S. cities. Weekly search volume for the terms diarrhea and vomiting was used as the response variable with the number of pipe breaks in each city as a covariate as well as additional covariates to control for seasonal patterns, search volume persistence, and other sources of GI illness. The fit and predictive accuracy of multiple regression and data mining techniques were compared, with the best performance obtained using random forest and bagged regression tree models. Pipe breaks were found to be an important and positively correlated predictor of internet search volume in multiple models in both cities, supporting previous investigations that indicated an increased risk of GI illness from distribution system disturbances.

Modifying Power Quality's Indices of Load by Presenting an Adaptive Method based on Hebb Learning Algorithm for Controlling DVR

Having electricity with high quality is one of the more important aims in electrical systems. Disturbances in distribution systems can change voltage waveform. There are some methods to prepare high power quality for sensitive loads. In this research we use “Dynamic Voltage Restorer” to compensate the harmful effects of disturbances on voltage. Since power systems fundamentally have complicated dynamic behavior, especially during faults, “Hebb” learning self-tuning controller, which is a powerful adaptive controller, has been used. In order to improve the performance of this controller from point of view of power quality's indices, such as flash and sensitive load voltage THD, a new structure is proposed for this controller with fuzzification method. Simulation results indicate better operation of the system for the case of proposed controller. Voltage sag and harmonics in faulty conditions are both improved by the proposed controller. According to simulation results, it works better than both classical PI controller and conventional Hebb learning controller.

Design of A Smart Embedded Uninterrupted Power Supply System for Personal Computers

Digital equipment such as computers, telecommunication systems and instruments use microprocessors that operate at high frequencies allowing them to carry out millions or even billions of operations per second. A disturbance in the electrical supply lasting just a few milliseconds can affect thousands or millions of basic operations. The result may be malfunctioning and loss of data with dangerous or costly consequences (e.g. loss of production). That is why many loads, called sensitive or critical loads, require a supply that is protected. Many manufacturers of sensitive equipment specify very strict tolerances, much stricter than those in the distribution system for the supply of their equipment, one example being Computer Business Equipment Manufacturers Association for computer equipment against distribution system disturbances. The design of this uninterrupted power supply (UPS) for personal computer (PC) is necessitated due to a need for enhanced portability in the design of personal computer desktop workstations. Apart from its original functionality as a backup source of power, this design incorporates the unit within the system unit casing, thereby reducing the number of system components available. Also, the embedding of this unit removes the untidiness of connecting wires and makes the whole computer act like a laptop. Not to be left out is the choice of a microcontroller as an important part of the circuitry. This has eliminated the weight and space-consuming components that make up an original design. The singular use of this microcontroller places the UPS under the class of an advanced technology device.

A Matrix Converter for Compensating Unbalanced and Harmonic Input Voltages

A dynamic voltage restorer (DVR) based on an AC-AC converter is presented. It is able to compensate different common disturbances in distribution systems, with the purpose of improving the power quality delivered to the users. A prototype has been assembled to test the feasibility of the proposition. In this paper a modulation strategy based on the well known space vector modulation (SVM) algorithm is presented in order to synthesize controllable voltages in magnitude and waveform for compensation purposes. Unbalanced and harmonic distortion conditions in the supply voltages are taken into account. These results positively confirm the design, simulation, assembling, and expectations about the device.

Five Level Flying-Capacitor Multilevel Converter Using Dynamic Voltage Restorer (DVR)

This paper deals with dynamic voltage restorer (DVR) controlled by a five-level flying-capacitor multi level converter. To decrease the power-quality disturbances in distribution system, such as voltage imbalances, harmonic voltages, and voltage sags. The organisation of this paper has been divided into three parts; the first one eliminates the modulation high-frequency harmonics using filter increase the transient response. The second one deal with the load voltage; and the third is flying capacitors charged with balanced voltages. The MATLAB simulation results effectively for five level flying capacitor multilevel converters charged with balanced voltage regulation.

Tools for Success

The power industry is experiencing a radical transformation as a consequence of the introduction of the smart grid concept. Some of the main features of the smart grid are increased participation by customers and the abilities to accommodate all generation and storage technologies; enable new products, services, and markets; provide increased reliability and power quality; optimize asset utilization and operating efficiency; provide self-healing capability in response to distribution system disturbances; and operate resiliently against physical and cyber attacks and natural disasters.

Voltage enhancement in industrial distribution systems using narrow-band filters

This study presents a novel and efficient technique for extracting the most common voltage disturbances in distribution systems. The new technique depends on a new recursive implementation of the digital second-order narrow-band filters. The proposed extraction technique is accurate and simple. In addition, a generalised compensation strategy is developed and utilised for mitigating the most common voltage quality problems such as voltage harmonics, voltage unbalance, voltage sags, voltage swells and voltage flicker. The suggested technique and the mitigation results are validated by digital simulation results obtained from an industrial distribution system. Also, the experimental results are provided to prove the practicality of the proposed concepts.