A review on unified power quality conditioner control techniques assesses the feasibility and performance of different controls used to enhance Unified Power Quality Conditioner (UPQC) for making the efficient utilization at consumer levels. This is intended to present a broad overview on the unified power quality conditioner system control strategies used for the improvement of various power quality issues with recent developments in the field. It is noticed that several researchers have used different controls to check performance of the power system withmanagementsinglephaseand three-phase controls for the UPQC based on the unique function, task, application, or topology under consideration. Currently, there are so many industries using a high technology for the manufacturing and requiring a high quality of power supply. Therefore, the paper is focusing mainly on power quality disturbance and the control technique used to improve the quality of delivered power such as Unified Power Quality Conditioner (UPQC).

The purpose of the paper is to present practical experience in the design and protection of transmission capacitor banks connected to typical gas-insulated substations. The paper describes common transient phenomena associated with gas-insulated switchgears, and the design and configuration of transmission capacitor banks for mitigating issues related to transient recovery voltage impacts on the circuit breaker protecting the capacitor bank. The design of protective relaying for the capacitor banks, including restrike and arcing monitoring, is also described.

The failure of several transmission capacitor banks prompted The United Illuminating Company to perform an engineering study to evaluate the transient recovery voltage capabilities of existing 123-kV, oil-filled capacitor bank circuit breakers at the East Shore 115-kV substation. The study determined if the transient recovery voltage capability of existing bus and capacitor bank circuit breakers is sufficient for the present system configuration. Furthermore, the study determined the required design and application changes related to the circuit breakers and capacitor bank component equipment, required to ensure that the bus and capacitor bank circuit breaker transient recovery voltage capabilities are not exceeded. The study recommended a future capacitor bank configuration to mitigate transient recovery voltage issues. The results of the study also lead to an expansion of the study area to include an adjacent substation, Grand Avenue Substation, due to concerns about the required transient recovery voltage capabilities of new gas-insulated switchgear to be installed.

As utilities modernize their distribution systems to include wider use of advanced distribution automation (ADA) schemes, they need to assess the relevant distribution circuit configurations and reconfiguring capabilities, including the associated control and protection systems. The simulation of these ADA schemes along with the associated control systems overlay can lead to a better understanding of the value of these emerging capabilities and the ways they can be most effectively used. This panel presentation summary discusses using the control system overlay feature of an open-source distribution system simulator for modeling distribution automation schemes.

Common information model (CIM) objects have not been fully developed for all types of power distribution field equipment, distributed energy resources, relays, and other devices that need to be integrated and managed over a utilitypsilas enterprise. This paper examines where the CIM needs to be extended to handle these extra devices and data collected from them. It also highlights some advanced applications that would be able to take advantage of this data to provide enhanced information in order to more effectively manage the distribution system.

This work presents a case study on technology assessment for power quality devices. A system compatibility test protocol for power quality mitigation devices was developed in order to evaluate the functionality of three-phase voltage restoration devices. In order to case test this test protocol, a development platform with reduced power for DVR (Dynamic Voltage Restorer), the micro-DVR, was tested, and results were discussed based on voltage disturbances standards.

Power quality data collected from power quality monitoring instruments are generally voluminous. They are typically stored without analysis unless there is a concern about a particular problem. Data analysis on a regular basis is time consuming and costly. Ideally, analysis modules should be made available to analyze data and construct important information about the health condition of the overall power system and its individual components. This paper presents the application of the well-known statistical process control to analyzing harmonic trend variations. Specifically, it describes how the method can be used to determine if the statistical variation in the harmonic trend represents normal variations or due to problems in the system.

Fault location is of considerable interest for utilities to improve their reliability and speed storm restorations. Power quality recorders, relays, and other monitors can provide information to help locate faults. In this paper, some basic impedance-based fault-location methods are evaluated on utility measurement data with known fault locations. The main finding is that reasonably accurate fault locations are possible on a wide range of distribution circuits with either feeder-level or bus-level substation monitoring. Another important finding described is how monitoring can be used to estimate the parameters of the fault arc. This can improve fault locations and help with accident investigations, equipment failure forensics, and other hazards related to the power and energy created by the arc

The system impact of a new transit substation may include harmonic distortion, voltage unbalance and flicker. Measurements were taken at a similar substation, and system simulations were performed for the planned substation. It was found that the Metro North train load produced significant levels of third harmonic current. Resonances in the 115 kV system were simulated and found to be at frequencies which are not critical. The decision as to whether to install a harmonic filter is a difficult one. Unbalance and flicker were found to be negligible.

A planned electric utility substation supplying the single-phase traction load at New Haven, CT, USA was evaluated with regard to several important aspects of power quality. Harmonics: the trains are non-linear and time-varying loads. Harmonic current levels were measured at a nearby single-phase traction substation, which serves the same line as the future New Haven substation. These results show that the third harmonic current and the total demand distortion (TDD) exceed the limits recommended in IEEE Standard 519-1992, IEEE (1993), hereafter referred to as IEEE 519. Voltage unbalance: the traction load is supplied by two 15-MVA single-phase transformers, each connected across phases A–C of the 115-kV line. Measurement results at a nearby 115-kV substation indicate a voltage unbalance of less than 1%, which is well within acceptable limits. Calculations for the New Haven substation location similarly show a voltage unbalance of less than 1%, with a 15-MVA load. Voltage fluctuations: the variable traction load can introduce flicker, a voltage fluctuation, which produces annoying visual changes in the intensity of electric lights. The measurement results at the nearby 115-kV substation show both the short-term (Pst) and long-term (Plt) flicker indicators are well below the recommended limits of 1.0 and 0.8, respectively.

This paper discusses the theoretical and practical aspects of various methodologies currently used for definition and characterization of voltage sags and short interruptions. Existing power-quality standards and procedures that are recommended for classification and presentation of sags and interruptions are critically reviewed and their shortfalls are highlighted.

An EMTP-based arc furnace model was developed for evaluation of flicker concerns associated with supplying a large integrated steel mill as they go from one to two furnace operation and as system changes are implemented that will affect the short circuit capacity at the 230 kV power supply substation. The model includes a dynamic arc representation which is designed to be characteristic of the initial portions of the melt cycle when the arc characteristics are the most variable (worst flicker conditions). The flicker calculations are verified using previous measurements with one furnace operation. Flicker simulations were then performed to evaluate a variety of different possible system strengths with both one and two furnaces in operation. The primary flicker measure used for this study is the unweighted RMS value of the fluctuation envelope, expressed as a percentage of the RMS line-to-ground voltage magnitude.

The definitions and formulas used today for common power system measures such as active, reactive, and apparent power have been in use since the 1940's. When these definitions were developed, loads were dominated by motors, lighting and other linear loads. Simplifications in calculations could then be made by taking advantage of the assumption of relatively balanced and non-distorted voltages and currents. Times have changed. Power electronic devices such as computer power supplies, phase controlled rectifiers, static VAr systems, cycloconverters, and other nonlinear, harmonic producing loads dominate today's loads. Also loads are more dense in commercial environments and due to the increased loads being added in an unplanned fashion in individual office environments, the assumptions regarding balanced loads are less valid than before. This paper summarizes how the new IEEE 1459 Trial-Use Standard addresses these issues with mathematically rigorous, yet useful and often intuitive definitions for power related quantities under sinusoidal, nonsinusoidal, balanced or unbalanced conditions.

Although capacitor switching transient events are one of the most common disturbance events on distribution systems, information on whether the capacitor bank is energized properly or as desired is often not available. The capacitor switching performance tracker is designed to examine capacitor switching transient events and determine the condition relative to the events. The module identifies if the root cause of the event is due to energizing a capacitor bank. It then determines the relative location of the bank, i.e., upstream or downstream from the monitoring location, and examines if the kVAr generated from the capacitor bank is added properly to the system and if the kVAr is distributed evenly among all phases. By determining the kvar changes, it is possible to identify unsuccessful energization, blown fuses, or even failed capacitor cans on one of the phases.

Understanding the performance of the power system is becoming increasingly important. This performance information must be available in a form that customers can use to evaluate the impacts on their processes and to evaluate the economics of power quality improvement alternatives. The performance information should also be shared throughout the utility so that problem areas can be identified and solutions implemented. Technologies to continuously monitor performance are available and the Internet provides a convenient method for sharing the information with all interested parties United Illuminating has implemented a monitoring system that tracks the performance at all distribution substations. The information is available at all times via the corporate intranet so that disturbances and long term power quality issues can be conveniently evaluated and so that information to be shared with customers can be provided easily by customer service personnel This paper describes the power quality monitoring system and the information sharing technology. Important benefits of the system that have been realized by United Illuminating are described, including power quality and reliability, prioritizing system improvements, and identifying problem conditions

This paper discusses the application of the revised IEEE-519 Harmonics standards to typical industrial facilities employing adjustable speed drives (ASDs). The harmonic generation characteristics of ASDs are described, Requirements for control of the harmonic currents are developed as a function of the ASD characteristics, overall plant loading level, power system characteristics, and power factor correction requirements. Filter design procedures are presented for controlling the harmonic currents injected onto the power system.

Who will be responsible for the quality of being delivered in the deregulated utility industry? The characteristics and sensitivity of end use equipment within customer facilities ultimately define power quality requirements. Improving the energy efficiency and productivity of industrial and commercial facilities can sometimes result in the use of technology that either causes power quality problems or is sensitive to power quality variations. Historically, utilities have only become involved in power quality problems that they caused to their customers. In the deregulated industry, the concepts of utilities and their customers are blurred. What are the power quality requirements at the interface between the transmission company and the distribution company? What is the base level of power quality that must be supplied by the distribution company to the end use customers? What kinds of enhanced power quality services can the energy service company offer to the end use customers? The answers to all of these questions must be developed in terms of the contracts between the different entities resulting from the utility industry deregulation. This paper describes some of the requirements for these contracts and ways of measuring performance to evaluate compliance with the contracts

Nonlinear loads are becoming a larger percentage of the total load in commercial facilities. Fluorescent lighting has always resulted in some harmonic generation. Now, single phase power electronic loads are a major portion of the load in many commercial facilities. They have become a problem for neutral conductors, transformer heating, and interference with other loads on the facility. Besides, single phase electronic equipment, many adjustable speed drives are now commonly applied for HVAC equipment. UPS equipment can have similar characteristics to the ASDs. The combination of these different nonlinear loads can also result in excessive injection of harmonic components from the customer facility onto the utility power system. Harmonic problems can be solved by controlling the harmonics in the loads themselves, through filtering (active or passive) on the electrical system, or by rating the system components to handle the harmonic levels. This paper discusses the expected harmonic levels in a facility as a function of the amount of nonlinear load of the different types. Alternatives for reducing harmonic distortion levels are discussed

This paper presents a summary of guidelines for modeling power electronics in various power engineering applications. This document is designed for use by power engineers who need to simulate power electronic devices and sub-systems with digital computer programs. The guideline emphasizes the basic issues that are critical for successfully modeling power electronics devices and the interface between power electronics and the utility or industrial system. The modeling considerations addressed in this guideline are generic for all power electronics modeling independent of the computational tool. However, for the purposes of illustration, the simulation examples presented are based on the EMTP or EMTP type of programs. The procedures used to implement power electronics models in these examples are valuable for using other digital simulation tools.