Showing papers on "Electric power system published in 1995"
Book•
01 Oct 1995
TL;DR: In this paper, the authors present a power quality evaluation procedure for the purpose of measuring the power quality of a power supply. But, they do not define the specific classes of power quality problems.
Abstract: CHAPTER 1: INTRODUCTION What is Power Quality? Power Quality -- Voltage Quality Why Are We Concerned About Power Quality? The Power Quality Evaluation Procedure Who Should Use This Book Overview of the Contents CHAPTER 2: TERMS AND DEFINITIONS Need for a Consistent Vocabulary General Classes of Power Quality Problems Transients Long-Duration Voltage Variations Short-Duration Voltage Variations Voltage Imbalance Waveform Distortion Voltage Fluctuation Power Frequency Variations Power Quality Terms Ambiguous Terms CBEMA and ITI Curves References CHAPTER 3: VOLTAGE SAGS AND INTERRUPTIONS Sources of Sags and Interruptions Estimating Voltage Sag Performance Fundamental Principles of Protection Solutions at the End-User Level Evaluating the Economics of Different Ride-Through Alternatives Motor-Starting Sags Utility System Fault-Clearing Issues References CHAPTER 4: TRANSIENT OVERVOLTAGES Sources of Transient Overvoltages Principles of Overvoltage Protection Devices for Overvoltage Protection Utility Capacitor-Switching Transients Utility System Lightning Protection Managing Ferroresonance Switching Transient Problems with Loads Computer Tools for Transients Analysis References CHAPTER 5: FUNDAMENTALS OF HARMONICS Harmonic Distortion Voltage versus Current Distortion Harmonics versus Transients Harmonic Indexes Harmonic Sources from Commercial Loads Harmonic Sources from Industrial Loads Locating Harmonic Sources System Response Characteristics Effects of Harmonic Distortion Interharmonics References Bibliography CHAPTER 6: APPLIED HARMONICS Harmonic Distortion Evaluations Principles for Controlling Harmonics Where to Control Harmonics Harmonic Studies Devices for Controlling Harmonic Distortion Harmonic Filter Design: A Case Study Case Studies Standards of Harmonics References Bibliography CHAPTER 7: LONG-DURATION VOLTAGE VARIATIONS Principles of Regulating the Voltage Devices for Voltage Regulation Utility Voltage Regulator Application Capacitors for Voltage Regulation End-User Capacitor Application Regulating Utility Voltage with Distributed Resources Flicker References Bibliography CHAPTER 8: POWER QUALITY BENCHMARKING Introduction Benchmarking Process RMS Voltage Variation Indices Harmonics Indices Power Quality Contracts Power Quality Insurance Power Quality State Estimation Including Power Quality in Distribution Planning References Bibliography CHAPTER 9: DISTRIBUTED GENERATION AND POWER QUALITY Resurgence of DG DG Technologies Interface to the Utility System Power Quality Issues Operating Conflicts DG on Distribution Networks Siting DGDistributed Generation Interconnection Standards Summary References Bibliography CHAPTER 10: WIRING AND GROUNDING Resources Definitions Reasons for Grounding Typical Wiring and Grounding Problems Solutions to Wiring and Grounding Problems Bibliography CHAPTER 11: POWER QUALITY MONITORING Monitoring Considerations Historical Perspective of Power Quality Measuring Instruments Power Quality Measurement Equipment Assessment of Power Quality Measurement Data Application of Intelligent Systems Power Quality Monitoring Standards References Index INDEX
1,991 citations
TL;DR: The main advantages of CPFLOW over repetitive power flow calculations are its computational speed and reliability as well as its wide applicability.
Abstract: In this paper, a computer package called CPFLOW, which is a comprehensive tool for tracing power system steady-state stationary behavior due to parameter variations, is presented. The variations include general bus real and/or reactive loads, area real and/or reactive loads, or system-wide real and/or reactive loads, and real generation at P-V buses (e.g. determined by economic dispatch or participation factor). The main advantages of CPFLOW over repetitive power flow calculations are its computational speed and reliability as well as its wide applicability. A detailed description of the implementation regarding the predictor, corrector, step-size control and parameterizations employed in CPFLOW is presented. CPFLOW has comprehensive modeling capability and can handle power systems up to 12000 buses. For an illustrative purpose, CPFLOW is applied to a 3500-bus power system with a comprehensive set of operational limits and controls. >
647 citations
Journal Article•
TL;DR: The goal of this paper is to promote better load modeling and advanced load modeling, and to facilitate data exchange among users of various production-grade simulation programs.
Abstract: The authors recommend standard load models for power flow and dynamic simulation programs. The goal of this paper is to promote better load modeling and advanced load modeling, and to facilitate data exchange among users of various production-grade simulation programs. Flexibility of modeling is an important consideration. For transient stability, longer-term dynamics, and small-disturbance stability programs, the authors recommend the structure of multiple load types connected to a load bus. Load types are static including discharge lighting, induction motors, synchronous motors, and transformer saturation. For each load type, multiple models may be connected to the bus. For longer-term dynamics programs, a model for LTC transformers is also recommended.
561 citations
TL;DR: In this article, the authors presented a new algorithm for studying the load shedding and generation reallocation problem in emergencies where a portion of the transmission system is disabled and an AC power solution cannot be found for the overloaded system.
Abstract: This paper outlines the optimization problem of real and reactive power, and presents the new algorithm for studying the load shedding and generation reallocation problem in emergencies where a portion of the transmission system is disabled and an AC power solution cannot be found for the overloaded system. The paper describes a novel and efficient method and algorithm to obtain the optimal shift in power dispatch related to contingency states or overload situations in power system operation and planning phases under various objectives such as economy, reliability and environmental conditions. The optimization procedures basically utilize linear programming with bounded variables and it incorporates the techniques of the Section Reduction Method and the Third Simplex Method. The validity and effectiveness of the algorithm is verified by means of two examples: a 10-bus system and the IEEE 30-Bus, six generators system. >
442 citations
01 Nov 1995
TL;DR: In this article, a theoretical foundation of direct methods for both network-reduction and network-preserving power system models is presented, along with numerical solution algorithms capable of supporting online applications of the direct methods.
Abstract: Stability analysis programs are a primary tool used by power system planning and operating engineers to predict the response of the system to various disturbances. Important conclusions and decisions are made based on the results of stability studies. This paper presents a theoretical foundation of direct methods for both network-reduction and network-preserving power system models. In addition to an overview, new results are offered. A systematic procedure of constructing energy functions for both network-reduction and network-preserving power system models is proposed. An advanced method, called the BCU method, of computing the controlling unstable equilibrium point is presented along with its theoretical foundation. Numerical solution algorithms capable of supporting online applications of direct methods are provided. Practical demonstrations of using direct methods and the BCU method for online transient stability assessments on two power systems are described. Further possible improvements, enhancements and other applications of direct methods are outlined.
412 citations
TL;DR: Concepts are described which provide design engineers with the insight to control performance and the understanding needed to ensure the secure operation of the bulk transmission system.
Abstract: The design of controllers sited in the transmission network for damping interarea power oscillations requires several types of analytical tools and field verification methods. Probably the most important aspect of such control design is the selection of proper feedback measurements from the network. This paper describes concepts which provide design engineers with the insight to control performance and the understanding needed to ensure the secure operation of the bulk transmission system. Specific attention is directed to procedures for selecting feedback signals. >
385 citations
TL;DR: In this article, an evolutionary programming (EP) method was applied to optimal reactive power dispatch and voltage control for large-scale power systems, and the proposed method has been evaluated on the IEEE 30-bus system.
Abstract: This paper is concerned with application of evolutionary programming (EP) to optimal reactive power dispatch and voltage control of power systems. Practical implementation of the EP for global optimization problems of large-scale power systems has been considered. The proposed EP method has been evaluated on the IEEE 30-bus system. Simulation results, compared with those obtained using a conventional gradient-based optimization method, are presented to show the potential of application of the proposed method to power system economical operations. >
340 citations
TL;DR: In this paper, the authors presented the general equations that relate the new concepts of instantaneous active and reactive power theory and the well known theory of symmetrical components for the case of 3-phase 4-wire systems, where zero sequence components and harmonics may be present in both voltages and currents.
Abstract: This paper presents the general equations that relate the new concepts of instantaneous active and reactive power theory and the well known theory of Symmetrical Components, for the case of 3-phase 4-wire systems, where zero sequence components and harmonics may be present in both voltages and currents. Based on these equations, new control algorithms for 3-phase 4-wire shunt and series active filters for unbalanced power systems are proposed and validated through simulations. The control algorithms presented here are very important for active power filter design and also for FACTS technology reactive power compensators. >
328 citations
TL;DR: In this article, the authors identify likely deregulation scenarios, identify the technical issues associated with load frequency control, and identify technical solutions, such as standards and algorithms, needed for the operation of this key component of national infrastructure in the face of profound structural changes.
Abstract: Open transmission access is a legal requirement in the United States, but is not fully implemented. Discussion of deregulation has so far focused principally on the tariff structure for transmission access, but operating the power system in this new environment will present significant problems of an almost purely technical nature. Something as simple as frequency control becomes challenging when implemented in the competitive, distributed control environment that true third party wheeling creates. This paper seeks to identify likely deregulation scenarios, identify the technical issues associated with load frequency control, and identify technical solutions, such as standards and algorithms, needed for the operation of this key component of national infrastructure in the face of profound structural changes.
318 citations
TL;DR: The proposed neural network has a quite simple structure and provides a highly accurate identification of the optimal operating point and also ahighly accurate estimation of the maximum power from the PV modules.
Abstract: This paper presents an application of a neural network for the identification of the optimal operating point of PV modules for the real time maximum power tracking control. The output power from the modules depends on the environmental factors such as insolation, cell temperature, and so on. Therefore, accurate identification of optimal operating point and real time continuous control are required to achieve the maximum output efficiency. The proposed neural network has a quite simple structure and provides a highly accurate identification of the optimal operating point and also a highly accurate estimation of the maximum power from the PV modules. >
301 citations
Patent•
21 Feb 1995
TL;DR: In this article, a battery charger coupled to an auxiliary primary operates as a boost converter to provide current to charge the battery at a current level which tracks the input voltage from the AC power system.
Abstract: An uninterruptible power system has a transformer with a primary connected to input terminals, a secondary connected to output terminals, a static switch connected between the input terminals and the primary, and an auxiliary primary connected to an inverter which is supplied by a battery to provide output voltage to the output terminals when a main AC power system connected to the input terminals has failed. The primary has multiple taps at different voltage levels and a buck-boost winding. The taps of the transformer are switched and the buck-boost winding is controlled to provide either buck, boost, or pass-by to allow control of the output voltage from the transformer to within a few percent of a desired voltage level despite large changes in the input voltage. A battery charger coupled to the auxiliary primary operates as a boost converter to provide current to charge the battery at a current level which tracks the input voltage from the AC power system, thereby providing a substantially unity power factor to the AC power system. The voltage control of the output voltage also controls the voltage at the output of the auxiliary primary to which the battery charger is connected, whereby the voltage applied to the charger is substantially regulated and the output power of the charger itself is substantially regulated. The charger can be operated in programmable modes to provide a desired charge configuration for the battery. Detection of faults in the AC power system is enhanced by accurate detection of the zero crossings of the input voltage from the AC power system, and by comparison of the AC input power waveform with an adaptive reference.
TL;DR: In this article, a generalized version of the unit commitment problem is formulated, which can treat minimum up-and down-time constraints, power flow constraints, line flow limits, voltage limits, reserve constraints, ramp limits, and total fuel and energy limits on hydro and thermal power generating units.
Abstract: The authors formulate a generalized version of the unit commitment problem that can treat minimum up- and down-time constraints, power flow constraints, line flow limits, voltage limits, reserve constraints, ramp limits, and total fuel and energy limits on hydro and thermal power generating units. They propose an algorithm for this problem, based on Lagrangian decomposition, and demonstrate the algorithm with reference to a simple model system. >
TL;DR: In this article, the development and utilization of an annual chronological load curve for each load bus in a composite generation and transmission system and a sequential Monte Carlo simulation approach for composite system reliability assessment are presented.
Abstract: The paper illustrates the development and utilization of an annual chronological load curve for each load bus in a composite generation and transmission system and a sequential Monte Carlo simulation approach for composite system reliability assessment. Antithetic variates as a variance reduction technique has been applied to the simulation model to increase the efficiency of the simulation. An approximate method using a load duration curve of the system load and an enumeration process have been applied to the developed load model and the results are compared in this paper. >
TL;DR: In this article, an experimental investigation of conducted radio-noise emission from a conventional pulse width modulated (PWM) inverter of medium power feeding an induction motor is described, and several low-cost strategies for improvement in EMI performance of the PWM inverter are then proposed.
Abstract: An experimental investigation of conducted radio-noise emission from a conventional pulse width modulated (PWM) inverter of medium power feeding an induction motor is described. It is determined that the inverter system generates considerable impulse currents through the power leads feeding the system resulting in serious conducted electromagnetic interference (EMI) problems and significant voltage waveform distortion in the power system. The dominant emission sources in the system are identified. A proposed model of the drive system for the purpose of evaluation of EMI are developed. Several low-cost strategies for improvement in EMC performance of the PWM inverter are then proposed. Experimental results demonstrate that disturbance from the modified system can be dramatically reduced, and that the EMC performance of the system has come very close to meeting the IEC CISPR and FCC limits on conducted emissions for digital devices.
TL;DR: New aggregation algorithms for obtaining reduced order power networks when coherent generators are aggregated will decrease the stiffening effect and produce, for the same coherent machine groups, aggregate networks with improved inter-area mode approximations.
Abstract: This paper presents new aggregation algorithms for obtaining reduced order power networks when coherent generators are aggregated. The generation terminal bus aggregation algorithm in the EPRI DYNRED software tends to stiffen the reduced order network during the aggregation process, thus increasing the frequencies of inter-area modes. The inertial and slow coherency aggregations will decrease the stiffening effect and produce, for the same coherent machine groups, aggregate networks with improved inter-area mode approximations. This paper contains new procedures to construct these aggregate networks and demonstrates the benefits of these new aggregate networks on a 48-machine power system using eigenvalues and nonlinear simulations. >
05 Apr 1995
TL;DR: Details on the design, architectural features and applications of a real-time digital simulator (RTDSm) developed at the Manitoba HVDC Research Centre (Winnipeg, Canada) are presented.
Abstract: Abstruct - This paper presents details on the design, architectural features and applications of a real-time digital simulator (RTDSm) developed at the Manitoba HVDC Research Centre (Winnipeg, Canada). Custom hardware and software have been developed and collectively applied to the simulation and study of electromagnetic transients phenomenon in power systems in real-time. The combination of real-time operation, flexible YO, graphical user interface and an extensive library of accurate power system component models make the RTDS an ideal simulation tool with a wide range of applications. I. INTRODUCTION Simulation has long been recognized as an important and necessary step in the development, design and testing of power generation and transmission systems. A wide variety of both analogue and digital simulation tools are available and typically used during various stages of system development. Recent advances in both computing hardware and sophisticated power system component modelling techniques have significantly increased the application of digital simulation in the power system industry. Of particular interest in the context of this paper are the advances made in the study of electromagnetic transients phenomenon.
TL;DR: A survey of publications on applications of fuzzy set theory to power systems and the basic procedures for fuzzy set based methods to solve specific power systems problems is presented.
Abstract: Increasing interest has been seen in applying fuzzy set theory to power systems problems from the number of publications on this topic. As a relatively new research topic a need is felt to pay more attention to the understanding of the basic principles of the theory and the identification of problems suitable for solving by this method. This paper presents a survey of publications on applications of fuzzy set theory to power systems and the basic procedures for fuzzy set based methods to solve specific power systems problems. Simple numerical examples are used to show the practical procedures of problem formulation and solution. Theses examples are: generator maintenance scheduling, dynamic programming, and power system stabiliser. >
TL;DR: In this paper, the design of an H/sub /spl infin controller for a series VAr compensator to enhance the damping of an inter-area oscillations in a large power system is presented.
Abstract: The design of an H/sub /spl infin controller for a thyristor controlled series VAr compensator to enhance the damping of an inter-area oscillations in a large power system is presented. The paper describes a comprehensive and systematic method of applying the H/sub /spl infin control design algorithm in power systems. Two methods to obtain a satisfactory reduced order system model, which is crucial to the success of the design, are described. >
TL;DR: In this article, detailed dynamic equations for the power system and wind energy conversion system (WECS) components and their synthesis to a unified model are presented, which is the basis for creating simulation software able to perform the transient stability analysis of isolated diesel-wind turbine power systems for accurate assessment of their interaction.
Abstract: In the first part of this two-part paper, detailed dynamic equations for the power system and wind energy conversion system (WECS) components and their synthesis to a unified model are presented. This model is the basis for creating simulation software able to perform the transient stability analysis of isolated diesel-wind turbine power systems for accurate assessment of their interaction. Approximations in the various component models, when necessary, remain between limits that do not affect the accuracy of the analysis performed. A new general multimachine power system model is also developed which describes the topology and the complexity of wind-diesel power systems in a compact form which is easy to implement in the simulation software. >
TL;DR: In this paper, a power line conditioner consisting of two small rating series active filters and a shunt passive filter is proposed to reduce voltage distortion at the connection point, and eliminate harmonic currents escaping into the system upstream of the connection points.
Abstract: This paper proposes a new power line conditioner consisting of two small rating series active filters and a shunt passive filter. The power line conditioner aims at a general filtering system which will be installed at the point of common coupling in a power system feeding harmonic-sensitive loads and unidentified harmonic-producing loads. One of the two active filters is connected in series with the supply, while another is in series with the shunt passive filter. The purpose of the power line conditioner is to reduce voltage distortion at the connection point, and is to eliminate harmonic currents escaping into the system upstream of the connection point. A control scheme of the two series active filters which play an important role is described in this paper. Its filtering characteristics are discussed with the focus on voltage and current distortion. A prototype model of 20 kVA is constructed to verify the functionality and performance of the power line conditioner. >
TL;DR: In this article, the relation between bifurcations and power systems stability through a thorough analysis of several examples, to clarify some ideas regarding the usefulness and limitations of Bifurcation theory in network studies and operation, particularly in voltage stability related issues.
Abstract: This paper discusses the relation between bifurcations and power systems stability through a thorough analysis of several examples, to clarify some ideas regarding the usefulness and limitations of bifurcation theory in network studies and operation, particularly in voltage stability related issues. Different types of load models are used in a sample system to analyze their effect on system stability and bifurcation. Finally, the Ecuadorian National Interconnected System is used to depict and discuss the effect of load modeling in saddle-node bifurcation analysis of real power systems. >
TL;DR: In this paper, a neural network based maximum power tracking controller for interconnected PV power systems is presented, where the neural network is utilized to identify the optimal operating voltage of the PV power system.
Abstract: This paper presents a neural network based maximum power tracking controller for interconnected PV power systems The neural network is utilized to identify the optimal operating voltage of the PV power system The controller generates the control signal in real-time, and the control signal is fed back to the voltage control loop of the inverter to shift the terminal voltage of the PV power system to its identified optimum, which yields maximum power generation The controller is of the PI type The proportional and the integral gains are set to their optimal values to achieve fast response and also to prevent overshoot and also undershoot Continuous measurement is required for the open circuit voltage on the monitoring cell, and also for the terminal voltage of the PV power system Because of the accurate identification of the optimal operating voltage of the PV power system, more than 99% power is drawn from the actual maximum power >
Patent•
24 Jan 1995
TL;DR: In this paper, the relay switch is closed and the inverter is turned off to allow the main power system to provide power to the load, but is turned on again after a short period of time less than a cycle of the AC waveform.
Abstract: A backup power system has power supply lines extending from input terminals, connectable to a main AC power system, and output terminals, connectable to a load, with a relay connected in a power supply line. The AC input power is monitored and when a fault in the power is detected, the relay is opened and an inverter is simultaneously turned on to provide backup power from a battery to the output terminals at a phase and frequency synchronized with the AC input voltage before the fault occurs. When the AC power system power is restored, the inverter power is again synchronized with the AC input power at the input terminals, the relay switch is closed and the inverter is turned off to allow the main power system to provide power to the load. The inverter may be providing power to the power lines before the relay contacts are opened to minimize the disruption of power supplied to the load during transfers. The switching of the switching devices in the inverter is cut off if the current drawn by the inverter from the battery exceeds a current limit level, but is turned on again after a short period of time less than a cycle of the AC waveform to again attempt to provide power from the inverter to the load. This process may be repeated, if necessary, to provide power to loads which require higher currents during start-up of the load than during normal operation after start-up.
TL;DR: In this paper, a sequential sealed-bid and sealed-offer auction is applied to the pricing of electric power by using linear programming, which is a market-based approach for electric power pricing.
Abstract: The expected move to a market-based electric power industry will significantly change electric utility operations. These changes will fundamentally alter the pricing of electric power. How this pricing will be accomplished is a key issue. Traditionally, embedded cost based methods have been used. Spot-pricing has received attention as a possible approach in a market-based electric power environment. Another market-based approach is the use of auctions. This paper presents the application of a sequential sealed-bid and sealed-offer auction to the pricing of electric power by using linear programming. >
TL;DR: In this article, a hybrid filter topology and its control to prevent harmonic currents from entering the power system is presented, and the proposed topology enables practical implementation of active harmonic current filters.
Abstract: Use of nonlinear loads and devices in power systems is expected to grow rapidly. Examples are thyristor-controlled inductors for FACTS, converters for HVDC transmission and large adjustable speed drives. All of these loads inject harmonic currents into the power system. A novel hybrid filter topology and its control, to prevent such harmonic currents from entering the power system, are presented in this paper. Analysis shows that in the proposed filter, the power electronic converter, required to generate harmonic currents for compensation, has a rating of only 9% when compared to the converter rating in an active filter and approximately one-half of that in a series-hybrid filter discussed in the literature. The proposed topology enables practical implementation of active harmonic current filters. The control of this filter under transient conditions such as start-up and during steady state is demonstrated by means of simulations. Results from a scaled-down hardware prototype are presented to verify the simulations. >
TL;DR: In this paper, the results of simulations were used to predict the net harmonic currents produced by large numbers of single-phase desktop computers in a facility, such as a commercial office building.
Abstract: In this paper we use the results of simulations to predict the net harmonic currents produced by large numbers of single-phase desktop computers in a facility, such as a commercial office building. We take into account attenuation due to system impedance and voltage distortion, as well as diversity in harmonic current phase angles due to variations in power and circuit parameters. Using experimental and published data we establish ranges of circuit parameters for an equivalent 120 V, 100 W "base computer unit" and branch circuit, update our computer modeling code (described in previous papers) to iteratively handle the interaction between current and voltage harmonics, and use the code to predict the net harmonic injection currents at the point of common coupling (PCC) represented by a shared transformer connected to a stiff power system. The key contributions of this paper are: providing estimates of the net harmonic current injection due to distributed single-phase computer loads in Amps/kW, as well as in percent of fundamental current, for a wide range of system loading and voltage distortion conditions; and illustrating that the reduction in harmonic currents due to phase angle diversity (expressed in Amps/kW) is relatively independent of system loading, whereas the reduction due to attenuation increases significantly with system loading. >
TL;DR: In this paper, the interactions between the incremental changes of current harmonic phasors injected by a power system NL (nonlinear load) and the resulting variations of harmonic voltages and powers are analyzed.
Abstract: This paper analyses the interactions between the incremental changes of current harmonic phasors injected by a power system NL (nonlinear load) and the resulting variations of harmonic voltages and powers. It proves that it is not always possible, following simple measurements of individual harmonic powers, to decide if a certain harmonic current is harmful or useful. It is suggested that the NL "distortion" be evaluated with the help of a quantity called non60 Hz (nonfundamental) apparent power. >
21 Nov 1995
TL;DR: In this article, the transfer function model and the ARIMA model were applied to the short-term load forecasting by considering weather-load relationship for four types of customer in Taiwan power (Taipower) system, residential load, commercial load, office load and industrial load customers.
Abstract: Short-term load forecasting plays an important role in electric power system operation and planning. An accurate load forecasting not only reduces the generation cost in a power system, but also provides a good principle of effective operation. In this paper, the ARIMA model and transfer function model are applied to the short-term load forecasting by considering weather-load relationship. For four types of customer in Taiwan power (Taipower) system, residential load, commercial load, office load and industrial load customers, the summer ARIMA model transfer function model have been derived to proceed the short-term load forecasting during one week. To demonstrate the effectiveness of the proposed method, this paper compares the results of the transfer function model and the univariate ARIMA model with conventional regression. Besides, the transfer function model's accuracy of the load forecast on weekday and weekend is thoroughly investigated. To improve the accuracy level of load forecast, the temperature effect is considered in the transfer function. According to the short-term load forecasting for these four customer classes, it is concluded that the proposed method can achieve better accuracy of load forecast than the ARIMA model by considering the causality between power consumption and temperature.
TL;DR: In this paper, a new approach covering all the main aspects of secondary voltage control; pilot buses and control generators selection, the control law and the decentralization problem, is presented.
Abstract: Secondary voltage control was introduced in some European countries as a means to improve voltage security and operation. It is a closed loop system dedicated to keep the voltage of some load buses called pilot buses constant. In this paper, a new approach covering all the main aspects of secondary voltage control; pilot buses and control generators selection, the control law and the decentralization problem, is presented. This approach has been applied to the Spanish power system. Some of the results obtained are also presented.
TL;DR: In this article, a multilayer feed-forward artificial neural network (ANN) with error backpropagation learning is proposed for calculation of voltage stability margins (VSM) based on the energy method, a direct mapping relation between power system loading conditions and the VSMs is set up via the ANN.
Abstract: Voltage stability problems have been one of the major concerns for electric utilities as a result of system heavy loading. This paper reports on an investigation on the application of ANNs in voltage stability assessment. A multilayer feedforward artificial neural network (ANN) with error backpropagation learning is proposed for calculation of voltage stability margins (VSM). Based on the energy method, a direct mapping relation between power system loading conditions and the VSMs is set up via the ANN. A systematic method for selecting the ANN's input variables was developed using sensitivity analysis. The effects of ANN's training pattern sensitivity problems were also studied by dividing system operating conditions into several loading levels based on sensitivity analysis. Extensive testing of the proposed ANN-based approach indicate its viability for power system voltage stability assessment. Simulation results on five test systems are reported in the paper.