Optimal Placement of Fault Indicator and Sectionalizing Switch in Distribution Networks

Abstract

Distribution network automation is considered by power supply companies as an effective investment strategy to improve reliability and service quality. Switching devices and protective devices play an important role in the distribution automation system (DAS). This paper presents a novel method to optimize placement of fault indicators and sectionalizing switches in distribution networks with branch lines. The objective function of the proposed method includes the total cost of fault indicators and sectionalizing switches as well as interruption cost. Among different automation equipment, this paper considers fault indicators and remote controlled switches. Besides, manual switches are taken into account since their number and location have a significant impact on the optimal placement problem. Mixed-integer linear programming is used to model the problem, and the proposed model can be solved by large-scale commercial solvers. The solution to the problem is composed of the optimal number and location of fault indicators and sectionalizing switches. The validity of the proposed method is demonstrated by relevant case studies and sensitivity analysis. Moreover, the proposed method is applied to a real distribution network to verify its practicability. INDEX TERMS Fault indicator (FI), manual switch (MS), remote controlled switch (RCS), mixed-integer linear programming (MILP), reliability, distribution network.

Reliability-Oriented Electricity Distribution System Switch and Tie Line Optimization

“…As mentioned before, if a tie line, equipped with an RCS at its normally-open side, is installed at the end of a faulty distribution feeder and at least one RCS exists between the faulted feeder section and the downstream node, τ l,n is equal to the switching time of an RCS. However, in other cases, the lower bound of τ l,n for the node downstream of a faulted feeder section is determined by (14)- (17).…”

“…This is because, in this case, the right-hand side of (17) is 0 or less, while, in (16), it is not, so the latter governs the lower bound. However, if neither an MS nor an RCS is installed at the normally-open side of tie line (i.e., the tie line has not been constructed), (17) dictates the lower bound of τ l,n . This is due to the fact that if no tie line is installed (i.e., x r equals 0), (18) forces all investment variables of disconnect switches at tie line r to be 0, and, therefore, the right-hand side of (17) would be λ l RT l .…”

“…In addition to the benefits of tie lines, the impact of their potential failures is also considered in the proposed model. Furthermore, unlike [7], [8], [10]- [17], which used the total customer interruption cost as the unreliability cost of the DISCO, we leverage other reliability indices, based on which the unreliability cost a DISCO may incur in practical applications is calculated [18]. To be more specific, although, according to its classical definition in [19], the total customers' interruption cost can appropriately reflect the network performance in terms of service reliability, this index cannot be accurately calculated in practice owing to its dependence on the customer damage functions of load nodes, the values of which are difficult to assess.…”

“…Reference [16] extended the previous models so as to conduct simultaneous placement of fuses, reclosers, MSs, and RCSs. Also, in [17], Li et al proposed an MILP model for simultaneous deployment of fault indicators, MSs, and RCSs in a distribution network with branch lines. Finally, authors in [18] developed an MILP formulation for the optimal switch placement problem, which determined the type of tie switches at the reserve connection points.…”

“…Accordingly, in [3], [5], [9], no tie line exists at the end of network feeders. Also, the existence of tie lines and type of tie switches in the network are determined prior to the placement of other switches [4], [6]- [8], [10]- [17]. Lastly, although the MILP model in [18] determines the type of tie switches as a result of the optimization, it assumes that the existence of tie lines is specified prior to the optimization.…”