Sectionalizing Switches Research Articles

Single‐stage single‐phase multiport DC–AC inverter suitable for standalone applications due to its notable performance in different operation modes

AbstractA new multiport DC–AC converter is proposed for standalone and off‐grid tied applications. The configuration converts power from DC to AC form in a single stage with suitable voltage gain. To increase the certainty of supporting power, the converter is designed to operate in four modes, including battery‐alone mode. The other advantage of the presented work is supplying the output power during unbalanced voltage conditions of the input ports. The advanced features of the converter for being used in standalone applications are related to the suitable placement and structure of the bidirectional port. In addition, the configuration is designed in a way to contain appropriate structural properties such as the existence of a common ground between the DC section and inverter, continuity of input currents, configured by an acceptable number of components, and low‐voltage stress on the DC–DC section's switches. Furthermore, it has an impedance network to protect the inverter's switches in a shoot‐through state. To confirm the converter advantages from the mentioned points of view, it has been compared with similar configurations. A prototype rated at 110 V is prepared to demonstrate the advantages of the converter performance per different conditions. The results of the steady‐state and transient experiments validate the suitability of the presented converter.

Resilience-oriented sectionalizing and tie switches sitting in distribution networks with complex topologies

Sectionalizing switches (SSs) are one of the most important tools that play a fundamental role in reducing the outage time of customers in electricity distribution networks. According to the radial exploitation of distribution networks, placing tie switches in the network can reduce the number of blackouts and interruptions in the event of a fault and improve the resilience and reliability indicators of the network. In this article, a suitable solution for sectionalizing switch placement (SSP) is proposed to increase the resilience of the distribution system during extreme weather events. The SSP problem is formulated as a two-step stochastic optimization problem. Decisions about the location of SSs are made under budget constraints in the first step. Then, to minimize the costs, in the second step, the renewal of the network is used. Also, at this step, using Monte Carlo simulation (MCS), scenarios are created to generate faults in random locations. The proposed model can also be implemented for networks that have multiple laterals and obtain the optimal position of tie switches and the location and type of SSs (i.e., remote or manual). The experimental networks studied, show the application of the presented model in improving the resilience and reliability indicators.

Bi-Level Coordinated Planning of Sectionalizing Switches and Tie Lines Considering Operation Mode Adjustment

Distribution utilities can flexibly control distribution networks by allocating the automatic and remotely controlled sectionalizing switches (SSs), which work with tie lines (TLs) to speed up fault management and are alternative devices for distribution operation mode adjustment. Hence, the SSs and the TLs play an important role in distribution networks. In order to improve the reliability of power supply and achieve economic distribution network operation, this paper proposes a bi-level SSs and TLs planning model, which considers distribution operation mode adjustment to optimize the allocation of SSs and TLs. The upper level of the proposed model aims at minimizing the sum of the total investment cost, the customer interruption loss cost, and the line loss cost. The upper level identifies the number and location of the SSs and the TLs. With the planning scheme obtained from the upper level, the lower level of the model adjusts the distribution operation mode to minimize the distribution line loss. In addition, binary particle swarm optimization (BPSO) is used because it has stable convergence and effectively explores the search space. A second-order cone programming (SOCP) is employed to reduce the complexity of the model and improve the solving process by linearizing the reconstruction calculation of the distribution network. Finally, simulation studies were conducted on bus 2 and bus 4 of the RBTS standard test system to assess the feasibility of the proposed model. The stability and effectiveness of the model are verified through various comparisons.

Flexible Joint Planning of Sectionalizing Switches and Tie Lines Among Distribution Feeders

This paper proposes an optimization model for the joint planning of sectionalizing switches (SSs), including remote-controlled switches (RCSs) and manual switches (MSs), and tie lines among distribution feeders. Considering a flexible installation of SSs and tie lines (i.e., deployment of SSs on both sides of a line and construction of external and internal tie lines on of a feeder), this model is conducive to developing an economic investment scheme while preserving the expected energy not supplied (EENS) reliability criterion. First, the minimum total cost of investment, maintenance and penalty for EENS is chosen as the objective function. Next, a route analysis method is introduced to analyze particular performances of different deployment schemes for RCSs, MSs, external tie lines and internal tie lines. Considering the differences between overhead lines and underground cables, the lower bound of the restoration time of each load is estimated based on optimal restoration strategies in different fault scenarios. Then, the joint planning problem is formulated as a mixed-integer linear programming (MILP) model with the aid of algebraic operations to calculate the global optimal solution. The effectiveness of the proposed model is verified for several cases in a 54-node distribution system. Numerical results indicate that the proposed planning solution merits higher economy and lower EENS as compared to the schemes offered by other prevalent methods.

An MILP Model for Optimal Placement of Sectionalizing Switches and Tie Lines in Distribution Networks With Complex Topologies

Sectionalizing switches (SSs) and tie lines play essential roles in reducing the duration of customer interruptions in electricity distribution networks. The effectiveness of such assets is strongly influenced by their placement in the grid. Operation of SSs and tie lines is also inherently interdependent. Due to the structural complexities regarding the mathematical modeling of such dependencies, optimization of the planning and operation of switches and tie lines has typically required either leveraging heuristic and metaheuristic approaches or oversimplifying the network topology. To tackle such issues, this paper presents a computationally-efficient model for reliability-oriented concurrent switch and tie line placement in distribution networks with complex topologies. The proposed model can be applied to grids with several tie lines and laterals per feeder, and yields the optimal location of tie lines, type of tie switches, namely manual or remote-controlled, and the location and type of SSs. Being cast as a mixed integer linear programming (MILP) problem, the model can be efficiently solved with guaranteed convergence to global optimality using off-the-shelf optimization software. The efficiency and scalability of the proposed model are demonstrated through implementation on five networks and the outcomes are thoroughly discussed.

Improved Method of Local Feeder Automation Considering Small Hydro-power Connection

With the access of small hydro-power stations (SHS), the distribution system presents a multiple power supply pattern, which has a negative impact on the original local feeder automation (LFA) which is suitable for single side power supply system. In view of this effect, the phase to phase short-circuit fault (PPF) and single-phase grounding fault (SPGF) are treated differently, and an improved LFA method (IMLFA) considering SHS’s access based on low-frequency load shedding (LFLS) and high-frequency generator tripping (HFGT) is proposed. In case of SPGF, the section switch (SSW) and the outgoing circuit breaker of the substation shall be opened in sequence, and the isolated network (IN) generated in the process can be operated stably by cooperating with LFLS or HFGT while the fault is preliminary isolated. The SSW and the breaker are added with the function of no-voltage detection and synchronization detection. In case of instantaneous fault, the power supply in the fault area can be restored after a series of operations, and the IN can be connected to the grid. If it is a permanent fault, the section switches (SSWs) around the fault area will be locked to close in order to isolate the fault effectively, and the IN, not separated by the fault area from the grid, can be connected to the grid. Analysis and simulation show that the method is correct and feasible.

Switches optimal placement of automated distribution networks with probability customer interruption cost model: A case study

Sectionalizing switches (SSs) have been installed in Distribution networks with the aim of providing maneuver and ring points, so raising service reliability. It is usually assumed that these switches are totally reliable although, in practice, they have not ideal efficiency at all times. In fact, the switches might occasionally face failure, which decreases their capability with the aim of enhancing system reliability. A model with the aim of considering the failure probability of the switches in their optimal placement issue is proposed in this paper. The model aids with the aim of minimizing the whole costs of SSs and the interruption costs incurred through interrupted users. This study uses the discrete Markov chain model with the aim of obtaining the malfunction possibility under various states. Afterwards, the placement problem is solved with the aim of obtaining the global optimal solution with genetic algorithm. The advantage of the suggested model has been investigated according to sensitivity analysis and various scenarios. The research illustrates how the outcomes of the placement issue have been influenced through the uncertainty arising from the possible failure of the switches and how ignoring the uncertainty is able to cause deviation of the anticipated profit from the real one. The efficiency of the suggested procedure has been evaluated and shown through investigating on the Ahwaz city distribution network. The outcomes of simulation prove the ability and precision of the suggested procedure.

Flexibility enhancement in active distribution networks through a risk-based optimal placement of sectionalizing switches

The advent of distributed energy resources (DERs) in distribution networks, referred to as active distribution networks (ADNs), brings in new opportunities for distribution network operators (DNOs) to improve the network reliability. The contribution of DERs in reliability enhancement generally depends on the island mode operation of DERs. Optimal placement of sectionalizing switches (SSs) enables ADNs to be operated more reliably by islanding the faulted part of the system in the form of flexible micro-grids (FMGs). However, practical methods are needed to handle the complex problem of the SS placement in ADNs. This paper presents a risk-based two-stage mixed-integer linear programming (MILP) model for the optimal placement of the network-driven flexibility providers, i.e. SSs, in ADNs taking into account the limits of the resource-driven flexibility providers, i.e. DERs. The performance of the proposed model is evaluated on various test distribution networks, and its effectiveness demonstrated through several case studies.

Effect of sectionalizing switches malfunction probability on optimal switches placement in distribution networks

Sectionalizing switches (SSs) are installed in distribution networks to provide ring and maneuver points, thereby increasing service reliability. These switches are either manual switches (MSs) or remote controlled switches (RCSs). The switches are usually assumed to be fully reliable. However, in practice, their performance is not always ideal. Actually, the switches may sometimes experience malfunction, which reduces their ability to enhance system reliability. The present study proposes a model to consider the malfunction possibility of the switches in their optimal placement problem. The model helps to minimize the total costs of SSs as well as the interruption costs incurred by interrupted customers. In order to calculate the malfunction probability of the switches, historical data on operation of the switches and their repair time are obtained from an electric power distribution company in Iran. The discrete Markov chain model is used to obtain the malfunction probability under different modes. The placement problem is then modeled in mixed integer linear programming (MIP) which can be easily solved to obtain the global optimal solution. The effectiveness of the proposed model is revealed by means of multiple case studies and sensitivity analyses. The studies show how the results of the placement problem are affected by the uncertainty caused by the probable malfunction of the switches and how overlooking this uncertainty can lead to deviation of the expected profit from the actual one.

An MIP-based model for the deployment of fault indicators and sectionalizing switches in distribution networks

Fault indicators (FIs) and sectionalizing switches (SSs) are of great importance in distribution automation for reliability enhancement and efficiency improvement. However, their types and locations have great effects on the resulting service quality. This paper intends to develop a model for the optimal simultaneous allocation of FIs and SSs in a complex distribution network based on reliability and cost-benefit analyses. Three position matrices are obtained by preprocessing the topology of distribution networks to enable the establishment of the proposed model. Furthermore, a quantification method for the customer interruption duration under different contingencies is constructed to achieve a more precise and practical reliability evaluation. The resultant optimization problem is formulated as a mixed-integer linear programming that can obtain the global optimal solution in a finite number of iterations. An IEEE 33-bus network and a real urban distribution system are used to verify the effectiveness and efficiency of this model. The obtained outcomes show that simultaneously considering the placement of FIs and SSs can expedite the fault location and isolation processes, reduce the overall costs of the system and improve the service reliability.

Risk-based Switch Placement in Electric Distribution Network in Presence of Performance Based Regulation

A reward and penalty scheme (RPS) is used for setting up the service quality which exposes the distribution companies to financial benefits caused by demand for the reliability of customers. In this paper, an algorithm for the optimal switch number and placement in distribution networks in the presence of RPS is presented. The primary objective is reliability improvement and minimization of the cost of sectionalizing switches (SS) and tie switches (TS) for a given regulatory period considering acceptable financial risk. In this algorithm, the uncertainty in the reliability is appeared as financial risk. A genetic algorithm is adopted to solve the optimization problem. The number and location of SS and TS is found while financial incentives of RPS, capital investment and annual operation and maintenance costs are considered. The performance of the proposed approach is assessed and illustrated on a real distribution network. The results show the efficiency of the proposed algorithm.

Optimal Placement of Sectionalizing Switch Considering Switch Malfunction Probability

Sectionalizing switches (SSs) are often presumed to function fully reliable. However, SSs are exposed to have some malfunctions, whereby undermining their ability to improve service reliability. This paper presents a model to integrate SS malfunction probability into SS placement problem. The model aims to minimize the total SSs costs as well as customers interruption cost. The proposed model is formulated in mixed integer programing, which can be easily solved via several available solvers and gain global optimal solution. The proposed model indicates the extent to which the placement problem is affected by uncertainty associated with SSs functionality, and how not considering SSs malfunction overestimates their benefits. The effectiveness of the proposed method is demonstrated through various case studies and sensitivity analyses. Moreover, the applicability of the proposed model in practice is examined by applying it on a real-life distribution system.