Loss Of Load Cost Research Articles

Composite Power System Reliability Evaluation Considering Stochastic Parameters Uncertainties

In electrical power systems, the impact of interruptions due to failures can be reduced through expansion planning studies. While high investments result in very expensive and more reliable decisions, reduced investments can lead to unreliable systems. Therefore, it is evident that economic and reliability constraints are conflicting, which makes decision-making difficult in planning and operation stage. The reliability theory, based on probabilities and stochastic processes, allows modeling the random behavior of equipment to estimate performance indices such as Loss of Load Cost. However, parameters as equipment failure rate and repair time are subject to random variations due to limited or nonexistent operating histories, aging and statistical errors. This paper proposes a technique for considering uncertainties on stochastic equipment data in power systems expansion planning. Based on the Monte Carlo Simulation, the proposed technique uses Interval Arithmetic as a method for calculating uncertainty through the theory of imprecise probabilities (P-Box). The application in a test system and a real transmission system allows observing the behavior of the reliability cost as well as the final cost of alternatives for expansion of these systems with the consideration of uncertainties along the expansion horizon.

Optimal Configuration of Large-Scale Storage Energy Access to Actual Power Grid with High Wind Power Proportion

In order to solve the problem of abandoned wind power in new energy high permeability grid, a large-scale energy storage device optimization configuration algorithm is proposed. At the same time, the energy storage cost, the abandonment cost and the loss of load cost are taken into consideration, and an optimization model is established considering various operational constraints and solved through the mature commercial software CPLEX. Finally, the 750kV system obtained by the actual grid equivalent is taken as an example to obtain an optimal configuration scheme for energy storage in the actual power grid.

Stochastic transmission expansion planning incorporating reliability solved using SFLA meta-heuristic optimization technique

This paper addresses stochastic transmission expansion planning (TEP) under uncertain load conditions when reliability is taken into consideration. The main objective of the proposed TEP is to minimize the total planning cost by denoting the place, number, and type of new transmission lines subject to safe operation criteria. In this paper, the objective function consists of two terms, namely, investment cost (IC) of new lines and reliability cost. The reliability cost is incorporated as the loss of load cost (LOLC). Network uncertainties in the form of loads are molded as Gaussian probability distribution function (PDF). Monte-Carlo simulation is applied to tackle the uncertainties. The proposed stochastic TEP is expressed as constrained optimization planning and solved using shuffled frog leaping algorithm (SFLA) SFLA is compared to other optimization techniques such as particle swarm optimization (PSO) and genetic algorithms (GA). Finally, stochastic planning (planning including uncertainty) and deterministic planning (planning excluding uncertainty) are compared to demonstrate impacts of uncertainty on the results. Simulation results in different cases and scenarios verify the effectiveness and viability of the proposed stochastic TEP, including uncertainty and reliability.

Economic Designing of PV/FC/Wind Hybrid System Considering Components Availability

Abstract — This paper presents an Optimization Sizing of a stand-alone PV/FC/Wind Hybrid System (PFWHS) to optimize the sizes of components of PFWHS. Based on PSO algorithm, one optimal sizing method was developed to determine the optimal configuration of system that can achieve the load required power supply probability (Reliability) with a minimum overall cost of energy (OCE).PFWHS costs involve investments, operation and maintenance as well as loss of load costs. The applied wind and radiation datasets belong to northwest region (Jolfa, latitude: 38_56, longitude: 45_37, altitude: 710, m) of Iran. In this paper the impact of availability of PFWHS components is investigated on optimal sizing. So, to investigating the impact of component availability rate on costs and PFWHS reliability due to failure and repair rate of PFWHS components and uncertainty in wind speed and solar irradiance, two scenarios are considered. In first scenario the availability of all components is considered 1 and in second scenario isn’t considered 1 because of failure and repair rate of components and uncertainty in wind speed and solar irradiance. Obtained results prove that while the overall cost of energy is optimized, the reliability indices are within a satisfactory bound with regard to the reliability standards. Also the results indicate that considering complete availability of components causes more reliability rate, so to achieve the actual behavior of PFWHS, the rate of components availability must be considered in suitable insight to designer for supply the load.

Optimal sizing of reliable hybrid renewable energy system considered various load types

In this paper, a novel intelligent method is applied to the problem of sizing in a hybrid power system such that the demand of residential area is met. This study is performed for Kahnouj area in south-east Iran. It is to mention that there are many similar regions around the world with this typical situation that can be expanded. The system consist of fuel cells, some wind units, some electrolyzers, a reformer, an anaerobic reactor, and some hydrogen tanks. The system is assumed to be stand-alone and uses the biomass as an available energy resource. System costs involve investments, replacement, and operation and maintenance as well as loss of load costs. Prices are all empirical and components are commercially available. In this study, we consider load growth and different types of load profile for their system. In this village, four types of loads exist such as residential, agricultural, industrial, and official loads. Also we consider load growth for the loads. Particle swarm optimization algorithm is used for optimal sizing of system’s components.

Reliability worth applied to transmission expansion planning based on ant colony system

This paper proposes a new methodology to solve transmission expansion planning (TEP) problems in power system, based on the metaheuristic ant colony optimisation (ACO). The TEP problem includes the search for the least cost solution, bearing in mind investment cost and reliability worth. Reliability worth is considered through the assessment of the interruption costs represented by the index LOLC – loss of load cost. The focus of this work is the development of a tool for the multi-stage planning of transmission systems and how reliability aspects can influence on the decision-making process. The applications of the proposed methodology are illustrated through case studies carried out using a test system and a real sub-transmission network.

Optimal design of a reliable hydrogen-based stand-alone wind/PV generating system, considering component outages

A hybrid wind/photovoltaic/fuel cell generation system is designed to supply power demand. The aim of this design is minimization of annualized cost of the hybrid system over its 20 years of operation. Optimization problem is subject to reliable supply of the demand. Three major components of the system, i.e. wind turbine generators, photovoltaic arrays, and DC/AC converter, may be subject to failure. Also, solar radiation, wind speed, and load data are assumed entirely deterministic. System costs involve investments, replacement, and operation and maintenance as well as loss of load costs. Prices are all empirical and components are commercially available. An advanced variation of Particle Swarm Optimization algorithm is used to solve the optimization problem. Results reveal the impact of component outages on the reliability and cost of the system, so they are directly dependent on components' reliabilities, i.e. outages result in need for a larger generating system for supplying the load with the acceptable reliability. Additionally, it is observed that the inverter's reliability is an upper limit for the system's reliability. Moreover, an approximate method for reliability evaluation of the hybrid system is proposed which considerably reduces the time and computations.

An approach to the explicit consideration of unreliability costs in transmission expansion planning

AbstractThis paper proposes a new methodology to explicitly consider unreliability costs in a multi‐stage transmission expansion planning. Starting from a reference plan, alternative expansion plans are derived based on postponement/anticipation of circuit implementations. These plans are then ranked by using an economic index of merit (EIM) and the associated Pareto‐optimal set is obtained through cost/benefit (trade‐off) analyses. The cost/benefit is related to the variation of investments and operational costs of each alternative transmission plan. Besides the usual operational costs (active power losses, fuels, etc.) the unreliability costs, due to random failures in the system, are also considered as operational costs. Therefore, reliability evaluations are carried out for all transmission expansion plans (TEPs) in order to compute reliability indices, such as the Expect Energy not Supplied and Loss of Load Cost (LOLC). To reduce the computational effort, pruning techniques are used to limit the number of possible TEPs. The proposed approach is applied to a configuration of the Brazilian North‐eastern system, considering a planning horizon of 10 years, to identify TEPs that are more balanced in terms of investment and reliability. Copyright © 2007 John Wiley & Sons, Ltd.

Avaliação da confiabilidade em sistemas de ditribuição considerando falhas de geração e transmissão

Este artigo apresenta uma nova metodologia para a análise da confiabilidade de sistemas de distribuição, onde se considera os impactos das falhas provenientes dos sistemas de geração e transmissão. Portanto, é viabilizada uma avaliação integrada, incluindo geração, transmissão (G&T) e distribuição, de modo a produzir uma informação mais detalhada sobre a causa das interrupções experimentadas pelos consumidores. O sistema G&T é representado por uma rede equivalente fictícia, cujos parâmetros são obtidos através de simulação Monte Carlo não-seqüencial. Esta rede equivalente G&T é conectada ao sistema de distribuição, que é então analisado utilizando a teoria dos conjuntos mínimos de corte. Índices de distribuição tradicionais (e.g. FEC, DEC, etc.) bem como a LOLC (Loss of Load Cost - Custo Esperado da Perda de Carga), são desagregados com o intuito de quantificar a contribuição dos sistemas G&T e distribuição em relação ao sistema total. O método proposto é testado em um sistema constituído pelo sistema de geração e transmissão IEEE-RTS, conectado ao sistema de distribuição IEEE-RBTS. Os resultados e suas potenciais aplicações para o novo cenário competitivo dos sistemas elétricos são discutidos.

Pseudo-chronological simulation for composite reliability analysis with time varying loads

This paper presents a new methodology to evaluate loss of load indices, with particular emphasis on LOLC (loss of load cost) assessment, for composite generation and transmission systems considering time varying loads for different areas or buses. The proposed approach, named pseudo-chronological simulation, retains the computational efficiency of nonsequential Monte Carlo simulation and the ability to model chronological load curves in sequential simulation. It considers the actual blocks of unsupplied energy per consumer class, per bus, and the respective duration, to accurately characterize the interruption process. Case studies on the IEEE-MRTS (Modified Reliability Test System) and the BSS (Brazilian South-Southeastern System) are presented and discussed.

00/00213 Comparison of alternative methods for evaluating loss of load costs in generation and transmission systems

00/00213 Comparison of alternative methods for evaluating loss of load costs in generation and transmission systems

Comparison of alternative methods for evaluating loss of load costs in generation and transmission systems

This paper presents a comparison among different methods to evaluate the loss of load cost (LOLC) index for composite generation and transmission systems. A new methodology is proposed and used as a reference to evaluate LOLC indices. It considers all blocks of unsupplied energy per consumer class, per bus, and the respective duration, to characterize accurately the interruption process. The proposed methodology is implemented with two composite reliability evaluation algorithms based on Monte Carlo simulation: sequential and pseudo-sequential. Also two load curtailment policies, minimum load curtailment and minimum cost, are considered and their impact on the different LOLC evaluation methods assessed. Case studies with the IEEE-MRTS (modified reliability test system) are presented and discussed.

Loss of load costs in generating capacity reliability evaluation

This paper presents a new methodology to calculate loss of load cost (LOLC) indices in generating systems. It is demonstrated that all previously proposed methods for evaluating LOLC indices are, in fact, approximations. Sequential Monte Carlo simulation, representing all possible chronological aspects, is used to calculate the probability distribution of the LOLC index. It is shown how the LOLC index, expressed in dollars per year, and the risk of not getting it, expressed as a probability or percentage, can be used in the expansion planning of generation systems. Both parameters, LOLC and risk, are established a priori as targets. Case studies with the IEEE Reliability Test system and the Brazilian Southeastern System are presented and discussed.

Application of chronological load modeling in composite reliability worth evaluation

This work describes the application of pseudo-sequential Monte Carlo simulation to the composite generation—transmission reliability evaluation of the Brazilian South-Southeast system using chronological load modeling. The resulting reliability indices, in particular the loss of load cost (LOLC), were compared with those produced by a sequential Monte Carlo scheme with chronological load model and by a non-sequential Monte Carlo simulation scheme using a multistate Markov load model. It is shown that the pseudo-sequential approach produced the same indices as the sequential approach, with a substantial reduction of computational effort. Those results were in turn quite different from the non-sequential Monte Carlo scheme, thus confirming the importance of an accurate load modeling.

Efficient loss-of-load cost evaluation by combined pseudo-sequential and state transition simulation

A new methodology to evaluate loss of load cost (LOLC) indices in composite generation and transmission systems is presented. The proposed approach is based on a combination of pseudo-sequential, state transition and conditional Monte Carlo simulation techniques. The approach can be easily implemented and it only requires models with stationary Markov transitions. Case studies with the IEEE Modified Reliability Test System and the Brazilian Southeastern System are presented and discussed.