Service Restoration Procedure Research Articles

Optimizing service restoration in distribution systems based on scheduling of crews considering priorities of loads

AbstractThe service restoration to sound sections within a short period as much as possible, performed after the permanent fault occurs in a distribution system, is significant for maintaining power supply reliability. This paper proposes an efficient method to find service restoration procedures based on fault searching and the optimal work scheduling of crews, considering the power supply priorities of loads and the probability of occurrence of faults. The proposed method is composed of two‐stage problems to reduce the outage sections efficiently: (i) the problem to find a series of searching procedures for unknown fault locations in the first stage and (ii) the optimization problem of work schedules of crews in the second stage. In the first stage, the order of operation of switches opened for searching for the fault direction is determined, constituting the searching tree. After that, the proposed optimization method can efficiently solve the work scheduling problem by formulating it as a mixed‐integer linear programming problem in the second stage. The computational experiments using a large‐scale distribution system model with many remote and manual switches show that the proposed method can provide efficient service restoration procedures within a reasonable computational time.

優先度および故障確率を考慮した作業スケジュールに基づいた故障復旧最適化

The service restoration to sound sections within a short period as much as possible, performed after the permanent fault occurs in a distribution system, is significant for maintaining power supply reliability. This paper proposes an efficient method to find service restoration procedures based on fault searching and the optimal work scheduling of crews, considering the power supply priorities of loads and the probability of occurrence of faults. The proposed method is composed of two-stage problems to reduce the outage sections efficiently: (i) the problem to find a series of searching procedures for unknown fault locations in the first stage, and (ii) the optimization problem of work schedules of crews in the second stage. In the first stage, the order of operation of switches opened for searching for the fault direction is determined, constituting the searching tree. After that, the proposed optimization method can efficiently solve the work scheduling problem by formulating it as a mixed-integer linear programming problem in the second stage. The computational experiments using a large scale distribution system model with many remote and manual switches show that the proposed method can provide efficient service restoration procedures within a reasonable computational time.

Service Restoration in Distribution Systems based on Optimal Scheduling of Search for Fault Location and Switching Operation by Crews

The service restoration within a short period, performed when the permanent fault occurs in a distribution system, is essential for high supply reliability. The service restoration can be achieved by searching the fault location and controlling switches to isolate the fault area. However, the service restoration faces difficulties in the uncertainty of the fault location and the multiple crews' scheduling of the switching operations. It is important to search for the unknown fault location efficiently and optimize the crews' scheduling for their service restoration procedures. This paper proposes an optimization method of the service restoration procedures performed by crews considering the search of the unknown fault location by crews to handle the difficulties. The proposed method combines an efficient fault location search with scheduling for multiple crews. We formulate the scheduling problem as a mixed-integer linear programming problem which allows us to schedule the procedures efficiently using optimization solvers. The proposed method is verified by the computational experiments using the large-scale distribution system model with many manual and remote switches.

Loss and reliability optimization for power distribution system operation

This study presents an optimization method that combines simultaneously the reliability and the efficiency of radial power distribution systems (RDS), minimizing active energy losses, through a process of network reconfiguration. The study is based on the failure analysis on network branches, with a special concern regarding the protection system response to faults and the service restoration procedures, during the emergency state. A non-sequential Monte Carlo simulation based on the branch reliability was used to evaluate reliability of the network configurations. Due to a large number of possible configurations and the need of an efficient search, the optimization is made through an improved genetic algorithm (IGA). The method analyses the RDS considering in a first step, the absence of investment, and in a second step, the possibility of placing a limited number of new tie-switches in certain branches, according to the definitions made by a decision maker. The effectiveness of the proposed methodology is demonstrated through the analysis of a 69 bus RDS and by comparison against other reported methodologies.

Development of an Object-Oriented Service Restoration Expert System With Load Variations

Distribution restoration process is done by switching actions of sectionalizing and tie switches on the feeders. The state of these switches can be determined by applying logical reasoning. Thus, knowledge-based systems are ideal tools to accomplish the task. In this paper, an expert system is developed by utilizing its fast reasoning mechanism and object-oriented features. The feeder component and configuration data are organized in a hierarchy way using the object-oriented programming paradigm. On the other hand, facts are used for representing the information during inference process. Service restoration procedure proposed in this paper takes load variation into consideration. The simulation results indicate that more solutions can be obtained for service restoration problems when load variation is considered. Another unique property of the proposed system is that it is capable of proposing multiple restoration plans. Multiple plans are important for the system operators since the best solution proposed by the system may not be workable in reality. By proposing multiple plans, the system operator can choose a plan which is more suitable to the real situation for service restoration problems.

A New Hybrid Multi-Objective Quick Service Restoration technique for Electric Power Distribution Systems

This paper presents a New Hybrid Multi-Objective Quick Service restoration (QSR) technique for Electrical Power Distribution Systems (EPDS). The main features of this new technique includes the development New Network Connectivity Method, objective function formulation with the consideration of various constraints in addition to the Priority Based Load Constraints and the incorporation of Service Restoration Time Estimation which helps the Electrical Power Distribution Engineers (EPDE) to restore the supply in minimum time. In order to satisfy various operational constraints while restoring the power supply to the consumer localities, the capacity of Transformer/Feeders in the post fault distribution network creates a serious problem to the EPDE and Distribution System Substation Operators (DSSO). Hence, the Electric Power Service Restoration Problem (EPSRP) becomes a nonlinear, combinatorial, non-differential and multi-objective optimization problem with several constraints. The solution to this multi-objective optimization problem has been obtained using a New Hybrid Method. A Computer program has been developed to solve this EPSRP. The validity of this new approach bas been tested on the various EPDS viz., 12-Bus, 15-Bus, 16-Bus, 26-Bus, 29-Bus, 33-Bus, 69-Bus, 79-Bus and 133-Bus systems. The fast and effective convergence of this approach helps to find the Optimal Operating Condition for the QSR of EPDS. The results reveal that it is a highly suitable technique for use in Service Restoration Procedures of Distribution Automation Systems (DAS).

Parallel genetic algorithm for service restoration in electric power distribution systems

This paper develops a coarse-grain parallel genetic algorithm for solving a service restoration problem in electric power distribution systems. Service restoration is performed to restore electricity for out-of-service areas. Developing effective service restoration procedures is a cost-effective approach to improving service reliability and enhancing customer satisfaction. The main objective in service restoration procedures is to restore as much load as possible by transferring de-energized loads via network reconfigurations to other supporting distribution feeders without violating operating and engineering constraints. Details of the parallel genetic algorithm developed in this paper are described. The proposed method is implemented on transputers for parallel computations. The feasibility of the developed algorithm for service restoration is demonstrated on several distribution networks with promising results.

Reconfiguration of radial distribution networks: application of heuristic methods on large-scale networks

Heuristic methods for the reconfiguration of radial distribution networks have been presented by several researchers. The objective of the studies involved is either to minimise resistive line losses during normal operation, or to balance load and relief overloads, e.g. during service restoration procedures. In the paper the two basic strategies employed and the adequate methods developed for both objectives are presented, improved and generalised. An efficient approach to the load balancing problem, using switch exchange operations, is presented. An overall algorithm for the reduction of the size of the network model without decreasing computations accuracy of all methods is also presented. The adequate computer programs are applied on a real, large-scale 20 kV Greek network, for the optimisation of its operation under normal operating conditions and after the occurrence of an outage. General conclusions are drawn regarding the comparison of the two strategies as modelled in the paper and the opportunities network reconfiguration offers for operation improvement.

Improving availability of software subsystems through on-line error detection

A VM/370 program called Auditor detects faults in the operation of computer software subsystems and attempts to restore service as quickly as possible. Through a series of periodic tests, Auditor diagnoses whether these subsystems are operating properly. When faults are detected, service restoration procedures are automatically called, and the persons responsible for the subsystems are notified. The various types of faults are recorded for subsequent analysis.

The Influence of Service Availability on the Configuration of Underground Three-Phase Primary Systems

The configuration of the underground primary system has a direct bearing on service availability. For this reason, service availability should be a dominant criterion in determining the optimum configuration for underground three-phase primary systems. This paper examines the influence of primary circuit configuration on the frequency and duration of service interruptions and on the service restoration procedure. Various arrangements of radial, open loop, and dual feed system elements are considered, with both manual and automatic sectionalizing equipment. The availability performance of a variety of total system configurations is determined by combining these system elements.

Transactions preprint of technical papers comprising pages 563–602 of the 1940 volume: Restoration of service on a metropolitan power system

THE purpose of this paper is to outline procedures and discuss pertinent problems that arise when restoring service to a metropolitan system following a major shutdown. In the discussion, consideration is given to the fundamental plan of the system, pointing out the inherent features in the design which prevent such failures. Several cases of trouble which have been the cause of service curtailment have been discussed and the service restoration procedure outlined. A brief outline of the essential procedure is given for two types of service restoration.