Reliability Improvement of Large Multi-state Series-parallel Systems

In the paper, excess methods for improving the reliability of multi-state series-parallel systems are presented： for the hot reserve of single components, the cold reserve of single components, and the mixed （hot and cold） reserve of single components. A process is also introduced to improve the reliability of these methods by replacing their components with more reliable ones. New theorems for multi-state limit reliability functions in homogeneous and non-homogeneous series-parallel large systems composed of components with improved reliability are presented, and applied to compare the effects of these systems in different reliability improving methods.

Improving the Reliability of Computer Communication Networks

For networks that are directed or can be represented by a directed network,reversing one or more of the uni-directional links may provide the ability to reconnect a network that has been disconnected by link failure, In this paper,a new approach to reconfigure such networks is proposed.We develop a linear time algorithm which,when reachability has been destroyed by the removal of a single link,optimally restores teachability through the reversal of selected links.Multi-link failure reconnectability is discussed and an algorithm with polynomial complexity is given which provides a nearly optimum solution to reconnect the network.We show that the reliability of a network that allows reversals is at least twice more than that in which reversals are not permitted.Unfortunately,the reconnection of some networks cannot be established.Therefore,we discuss the maximization of reachability of such networks so that each node can reach maximum number of the other nodes.

Optimal planning of battery energy storage considering reliability benefit and operation strategy in active distribution system

In this paper, a cost-benefit analysis based optimal planning model of battery energy storage system(BESS) in active distribution system(ADS) is established considering a new BESS operation strategy. Reliability improvement benefit of BESS is considered and a numerical calculation method based on expectation is proposed for simple and convenient calculation of system reliability improvement with BESS in planning phase. Decision variables include both configuration variables and operation strategy control variables. In order to prevent the interaction between two types of variables and enhance global search ability, intelligent single particle optimizer(ISPO) is adopted to optimize this model. Case studies on a modified IEEE benchmark system verified the performance of the proposed operation strategy and optimal planning model of BESS.

Internal electrical fault detection techniques in DFIG-based wind turbines: a review

The keys factor in making wind power one of the main power sources to meet the world’s growing energy demands is the reliability improvement of wind turbines(WTs).However,the eventuality of fault occurrence on WT com-ponents cannot be avoided,especially for doubly-fed induction generator(DFIG)based WTs,which are operating in severe environments.The maintenance need increases due to unexpected faults,which in turn leads to higher operating cost and poor reliability.Extensive investigation into DFIG internal fault detection techniques has been carried out in the last decade.This paper presents a detailed review of these techniques.It discusses the methods that can be used to detect internal electrical faults in a DFIG stator,rotor,or both.A novel sorting technique is presented which takes into consideration different parameters such as fault location,detection technique,and DFIG modelling.The main mathematical representation used to detect these faults is presented to allow an easier and faster under-standing of each method.In addition,a comparison is carried out in every section to illustrate the main differences,advantages,and disadvantages of every method and/or model.Some real monitoring systems available in the market are presented.Finally,recommendations for the challenges,future work,and main gaps in the field of internal faults in a DFIG are presented.This review is organized in a tutorial manner,to be an effective guide for future research for enhancing the reliability of DFIG-based WTs.