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This paper presents a framework to implement supply and demand side contingency management in the reliability assessment of hybrid power markets. A model for the independent system operator (ISO) to coordinate reserve and load curtailment bids for contingency states is introduced to balance reliability worth and reliability cost. The load curtailments and generation re-dispatch for a contingency state are determined based on minimizing the market interruption cost using an optimization technique. A nousequential Monte Carlo simulation technique based on this framework has been proposed to evaluate the customer reliability of restructured power systems with the hybrid market model. The modified IEEE Reliability Test System (RTS) is used to illustrate the proposed technique. Index Terms--Contingency management, customer reliability, hybrid market, independent system operator (ISO), load curtailment bids, market interruption cost, Monte Carlo simulation, reliability assessment, reserve.

In an open-access environment, available transfer capability (ATC) is a very important index indicating the transfer capability remaining in a physical power transmission network for further commercial trading. Total transfer capability (TTC), as a key component for determining ATC, is not deterministic, due to the random nature of transmission failures. This paper introduces a framework for determination of probabilistic TTC. An optimal power flow (OPF) technique based on the sequential quadratic programming is implemented to evaluate TTCs for different contingency states in an interconnected power system. A model for determining the optimal TTC is proposed based on maximizing transmission revenue. Different penalty cost models for the no-delivered TTC have been investigated. The bisection search method is used to reduce the computing time of searching the optimal TTC. The numerical results for the IEEE-RTS system are presented to demonstrate the effectiveness of the proposed models and solution techniques. Index Terms--Available transfer capability (ATC), bisection search method, optimal power flow, probabilistic approach, sequential quadratic programming (SQP), total transfer capability (TTC), transmission open access.

In a restructured power system with hybrid market structure, generation companies and customers trade electricity and reserve either through a centralized power pool or by bilateral contracts based on their price and reliability offers and requirements. This results in difficulty in price and reliability management of such power systems. This paper presents techniques to evaluate both reliabilities and prices for the pool and bilateral customers in a hybrid power market. In these techniques, reliability and price models for the power pool and bilateral suppliers have been developed using reliability network equivalents to easily include various agreements among market participants. Customer responses to prices are modeled using customer damage functions. The reliability and price problems with and without considering agreements are formulated using improved optimal power flow techniques based on these models. The correlation between reliabilities and prices has been considered in the techniques. The modified IEEE Reliability Test System has been analyzed to illustrate the proposed techniques. Index Terms--Hybrid power market, load shedding, market pricing, optimal power flow, reliability analysis, reliability network equivalent, restructured power system.

Market power assessment is an important aspect of electric market analysis and operation. Market power problems are more complicated in an electric market than those in other markets due to the specific properties of electricity. This paper investigates market power problems and the related solution techniques in an electric power market. The impact of load variation, the size of a power supplier and random failures on market power has been investigated. The geographic difference of market power caused by network constraints has been considered. Must run share (MRS) and nodal must-run share (NMRS) have been proposed to represent system and local market powers respectively. An optimization technique and the topological analysis of power flow have been used to determine the MRS and NMRS. Expected nodal must-run share (ENMRS) has been proposed to represent the impact of random failures on market power and the associated risk of customers paying a high price due to the exercise of market power. The contingency enumeration and probabilistic technique have been used to determine the ENMRS. The IEEE Reliability Test System is analyzed to illustrate the proposed indices and techniques. Index Terms--Expected nodal must-run share, market power, must-run share, nodal market power, nodal must-run share, power market, power system deregulation, transmission congestion.

This paper presents a technique to evaluate the customer load point reliability in a deregulated power system considering customer choice on reliability. In this technique, a generation company (Genco) is represented by an equivalent multistate generation provider (EMGP) and an equivalent multistate reserve provider (EMRP) based on the market function of a Genco. A Genco, which has reserve agreements with other Gencos, is represented by an equivalent multistate generation provider with reserve agreement (EMGPWR). The transmission system between a Genco and its customer considering reserve agreements is represented by an equivalent multistate transmission provider with reserve agreement (EMTPWR). Reliability network equivalent techniques have been extended and combined with the equivalent assisting unit approach to determine the reliability model of the EMGPWR. A procedure used to determine the reliability model of EMTPWR is also developed. The IEEE reliability test system is used to illustrate the techniques. Index Terms--Deregulated power system, reliability, reliability network equivalent, reserve management.

Unreliability cost evaluation of an entire power system provides a set of indexes which can be used by a system planner to balance the investments in different segments of the system in order to provide acceptable load point (LP) reliability. This paper utilizes reliability network equivalent techniques to evaluate the customer LP unreliability cost indexes caused by outages in different segments of the power system. The equivalent multistate generator (EMG), the equivalent mutistate lateral section (EMLS), and the equivalent multistate series element (EMSE) are introduced. The percentage distribution of unreliability costs for system segments is determined to find the weak segments in the system. A test system is analyzed to illustrate the application of these techniques. Index Terms--Network equivalent, reliability worth evaluation, unreliability cost.

Analytical techniques for distribution system reliability assessment can be effectively used to evaluate the mean values of a wide range of system reliability indices. This approach is usually used when teaching the basic concepts of distribution system reliability evaluation. The mean or expected value, however, does not provide any information on the inherent variability of an index. Appreciation of this inherent variability is an important parameter in comprehending the actual reliability experienced by a customer and should be recognized when teaching distribution system reliability evaluation. This paper presents a time sequential Monte Carlo simulation technique which can be used in complex distribution system evaluation, and describes a computer program developed to implement this technique. General distribution system elements, operating models and radial configurations are considered in the program. The results obtained using both analytical and simulation methods are compared. The mean values and the probability distributions for both load point and system indices are illustrated using a practical test system. Keywords: Reliability, Power distribution system, Monte Carlo simulation

The requirements for extensive justification of new facilities and emphasis on the optimization of system cost and reliability are steadily increasing. Customer interruption cost analysis provides valuable input to electric power supply reliability worth assessment. This paper presents both a generalized analytical approach and a time sequential Monte Carlo simulation technique for evaluating the customer interruption cost in complex radial distribution systems. Studies are conducted on two practical distribution systems. The results obtained using the analytical technique incorporating average restoration times are compared with those obtained using the time sequential simulation method and random restoration times. The effects on customer interruption cost indices associated with alternate supply and protection devices are also considered.

Uncertainty and geographical diversity of wind speeds create risk for a wind power generation company (WGenco) to make the maximum profit from power market trading. A probabilistic approach is proposed to estimate the profit of a WGenco considering geographical diversity and uncertainty of wind speeds and market prices. The objective of the optimization problem is to assist a WGenco to do the optimal bidding in market trading in order to make the maximum profit under various market and wind speed uncertainties. The point estimate method (PEM) has been improved to facilitate stochastic modeling of the aggregated power output of wind turbine generators in different locations in the problem formulation. The principal component analysis (PCA) is used to manage correlated wind speeds. [ABSTRACT FROM AUTHOR]