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In a deregulated power market, customers would have more choices for their power service and the improvement of service quality has become a challenge to power transmission and distribution companies. Distribution system reliability that was traditionally considered within the planning activities is now incorporated in the operational environment. This paper presents study results of a multiobjective feeder operation optimization problem that considers how to balance network efficiency, switching and reliability costs in a distribution network. The proposed method divides annual feeder load curve into multiperiods of load levels and optimizes the feeder configurations for different load levels in annual operation planning. Customer load profiles and seasonal varying data of feeder section failure rates and customer interruption costs are considered. Numerical simulations demonstrate the time-varying effects on the optimal distribution feeder configuration and operation costs. A binary particle swarm optimization (BPSO) search is adopted to determine the feeder switching schedule. Test results indicate that not considering time-varying effects and using only simplified fixed load and reliability parameters could underestimate the total loss to the utility and its customers. Index Terms--Customer interruption cost, distribution feeder reconfiguration, distribution system operation, system loss, system reliability.

A two-point estimate method is proposed in this paper to assess the power transfer capability uncertainty. This paper assumes that the uncertainty of the line parameters and bus injections involved in transfer capability calculations can be estimated or measured and shows how to estimate the corresponding uncertainty in the transfer capability. Instead of using a large number of simulations as required in the Monte Carlo approach, for a system with n uncertain parameters, the two-point estimate method uses 2n calculations of transfer capability to quantify the uncertainty. The proposed method uses a numerical method to calculate the moments of the transfer capability. The moments are then used in the probability distribution fitting. Using the obtained transfer capability uncertainty information and a desired level of reliability, an adequate transmission reliability margin can be determined for each transmission service. The proposed method can be used directly with a deterministic computer program and it does not require derivatives of the transfer capability. Test results of the proposed method are compared with those obtained from the Monte Carlo simulations and a truncated Taylor series expansion method. Index Terms--Point estimate method, transfer capability, transmission reliability margin, uncertainty.

This paper introduces a new approach to customer interruption cost evaluation that recognizes the dispersed nature of the cost data. The proposed method is designated as the possibility distribution approach and provides a realistic and effective assessment of the losses incurred by high-tech industry electrical users due to power failures. Fuzzy linear regression models are used to describe the distribution and dispersed behaviors of interruption costs. Bootstrap technique is used to generate a sampling distribution of small samples so that confidence intervals of interruption costs of different high-tech sectors can be obtained. Using the obtained cost models, interruption costs and reliability worth of high-tech industries that require higher reliability and premium power service, can be properly assessed. Index Terms--Fuzzy regression, interruption costs, reliability worth.

The model used for real-time network security and transmission capability analyses requires the use of a large area network and has to be brought up to 'real-time' conditions. To build a complete network model, supervisory control and data acquisition (SCADA) data have to be made available to many external bodies. In this paper, an Internet interface to SCADA systems is proposed for inter control center data exchange. A discrete event technique is utilized to simulate the interarea data exchange. The performance modeling of data exchange on the Internet is established, and a quantitative analysis of the data exchange delay is presented. Simulation and experimental results have indicated that the Internet provides a convenient way for intercontrol center data exchange and, by using state estimation (SE) accurate complete network models, can be obtained for practical security and available transfer capability analyses. Index Terms--Communication network simulation, complete network model, intercontrol center data exchange, security analysis.

In a competitive power market, locations of future load growth have to be described with sufficient geographic precision to permit valid marketing strategy and siting of future T&D equipment. Small area load forecast which provides information of future electric demand that includes spatial and temporal characteristics, is useful for T&D and market planning. Domain experts for spatial load forecast require long term practicing and are difficult to find. In order to capture the meaningful associations between spatial data and the load changes, and to provide a useful tool for spatial load forecast, a data mining technique based on a 'Knowledge Discovery in Database (KDD)' procedure is proposed to determine automatically the preferential 'scores' of land use changes. The proposed spatial modeling approach is an exploratory data analysis, trying to discover useful patterns in spatial data that are not obvious to the data user and are useful in the spatial load forecast. Index Terms--Data mining, fuzzy model, knowledge discovery in database, spatial load forecast.

Due to many unforeseen circumstances that could happen in the today's bulk power system, there is a possibility of a system wide outage. In order to provide aids to the power system dispatchers following a complete collapse of the power system, a prototype package has been developed. Through interactive and friendly graphic interface, the package suggests a guideline for the dispatcher to restore the power system. With an aim to increase the ease of maintenance, object-oriented technique was adopted to implement the package. The development of the software involved three stages: 1) Object oriented analysis, 2) Object oriented design, and 3) Integration and testing. In this paper, the structure and the development procedure of the prototype system are presented. Keywords - power system restoration, object-oriented technique

In current power system operations, transmission networks have been operated at their limits much more frequently and for much longer periods of time. Special protection systems (SPS) are attractive for increasing transmission capacity in a competitive market, but the installation costs and system reliability issues are important. In this letter, a risk-based method is proposed to take the uncertainty of contingency occurrence and impacts into account to provide an essential set of contingency cases for SPS implementation. Index Terms--Contingency selection, risk-based security assessment, special protection systems (SPS).

The ability of a regression tree method to properly interpolate among recorded data to give an estimate of the frequency decline following a generator outage is examined in this letter. The proposed method is a nonparametric technique that can select those system characteristics and their interactions that are most important in determining the relation between the generation/load imbalance and the frequency decline. The information obtained from the proposed method can be used online for scheduling fast-acting reserve or load shedding for severe generator outage incidents. Index Terms--Frequency control, generation/load imbalance, load shedding, regression tree, spinning reserve.

In an interconnected power system, the network security and power transfer capability analyzes require a complete network base case solution. With the advent of communications among operations control center computers, real-time telemetered data can be exchanged for complete network modeling. Measurement time skew is a consideration when combining large area data received via a data communication network. In order to accommodate the effects of randomly varying arrival of measurement data, this paper presents an implementation of a stochastic Extended Kalman Filter (EKF) algorithm, which provides optimal estimates of interconnected network states for systems in which some or all measurements are delayed. The method relies on the delay statistics of exchanged data arrival at the control center and the delay is assumed to have a binary statistics, i.e., either the measurements arrive in time or it is delayed by one time sample. Performance of the proposed method is compared with that of the standard Weighted Least Square (WLS) technique. Index Terms--Data exchange, Kalman filter, measurement delay, state estimation.