Resilience Maximization in Electrical Power Systems through Switching of Power Transmission Lines (original) (raw)
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Energies
Currently, operating electrical power systems (EPS) is a complex task that relies on the experience of the operators or the strength of algorithms developed for autonomous operation. The continuous operation of EPS is vulnerable to intentional cybernetic and physical attacks. With the most significant extension and distribution in the EPS, the transmission lines are most exposed to potential attacks. Before this, the entire behavior of the EPS changes, and, on occasions, a blackout can even be generated. The present investigation focused on developing a methodology for reconfiguring the power system against intentional attacks, considering the topology change through optimal switching of transmission lines (OTS) based on optimal DC flows and quantifying the contingency index, which allows for the identification of the weaknesses of the EPS. The methodology was applied to the IEEE 30−bus system, and contingencies were randomly generated, as is typical with intentional attacks. The st...
Energies
The reliability of the electrical system is a fundamental study that is carried out to determine the possible deficiencies that an electrical system can have in case of failures, since a failure can cause disturbances, power cuts, and load disconnections. For this reason, Optimal Transmission Switching (OTS) with Optimal AC Power Flows (OPF-AC) is used to reduce disturbances when faults occur and minimize equipment load and disconnections, but OTS offers possible switches in order to make it possible to reduce the damage that can be done for a fault with operating limitations in voltage, power, and angular deviation. However, to have a complete study, it is proposed to use a reliability analysis through contingency ranking to know the risks that a switched system may have at the time of simultaneous or consecutive failures. In addition, a load capacity investigation is conducted to determine if the transmission lines are within their operating limits. The study presents an analysis ...
Cascading Failure Mitigation Via Transmission Switching
Social Science Research Network, 2022
After decades of research, cascading blackouts remain one of the unresolved challenges in the bulk power system operations. A new perspective for measuring the susceptibility of the system to cascading failures is clearly needed. The newly developed concept of system stress metrics may be able to provide new insights into this problem. The method measures stress as susceptibility to cascading failures by analyzing the network structure and electrical properties. This paper investigates the effectiveness of transmission switching in reducing the risk of cascading failures, measured in system stress metrics. Based on line-outage distribution factors, an algorithm is developed to identify and test the switching candidates quickly. A case study analyzing different stress metrics on the IEEE 118-bus test system is presented. The results show that transmission switching identified by our proposed algorithm could be used in preventive as well as corrective mechanisms to reduce the system's susceptibility to cascading failures. Contrary to the conventional operation wisdom that switching lines out of service jeopardizes reliability, our results suggest the opposite; system operators can often use transmission switching, when the system is under stress, as a tool to reduce the risk of cascading failures.
Energies, 2021
Power systems face failures, attacks and natural disasters on a daily basis, making robustness and resilience an important topic. In an electrical network, robustness is a network’s ability to withstand and fully operate under the effects of failures, while resilience is the ability to rapidly recover from such disruptive events and adapt its structure to mitigate the impact of similar events in the future. This paper presents an integrated framework for jointly assessing these concepts using two complementary algorithms. The robustness model, which is based on a cascading failure algorithm, quantifies the degradation of the power network due to a cascading event, incorporating the circuit breaker protection mechanisms of the power lines. The resilience model is posed as a mixed-integer optimisation problem and uses the previous disintegration state to determine both the optimal dispatch and topology at each restoration stage. To demonstrate the applicability of the proposed framework, the IEEE 118-bus test network is used as a case study. Analyses of the impact of variations in both generation and load are provided for 10 simulation scenarios to illustrate different network operating conditions. The results indicate that a network’s recovery could be related to the overload capacity of the power lines. In other words, a power system with high overload capacity can withstand higher operational stresses, which is related to increased robustness and a faster recovery process.
A Power System Network Splitting Strategy Based on Contingency Analysis
Energies, 2018
This paper proposes a network splitting strategy following critical line outages based on N-1 contingency analysis. Network splitting is the best option for certain critical outages when the tendency of severe cascading failures is very high. Network splitting is executed by splitting the power system network into feasible set of islands. Thus, it is essential to identify the optimal splitting solution (in terms of minimal power flow disruption) that satisfies certain constraints. This paper determines the optimal splitting solution for each of the critical line outage using discrete evolutionary programming (DEP) optimization technique assisted by heuristic initialization approach. Heuristic initialization provides the best initial cutsets which will guide the optimization technique to find the optimal splitting solution. Generation-load balance and transmission line overloading analysis are carried out in each island to ensure the steady state stability is achieved. Load shedding scheme is initiated if the power balance criterion is violated in any island to sustain the generation-load balance. The proposed technique is validated on the IEEE 118 bus system. Results show that the proposed approach produces an optimal splitting solution with lower power flow disruption during network splitting execution.
Contingency Analysis of Power Networks : A System Theoretic Approach
arXiv: Optimization and Control, 2017
In this work, we have proposed a system theoretic method to compute sensitivities of different lines for N−kN-kN−k contingency analysis in power network. We have formulated the N−kN-kN−k contingency analysis as the stability problem of power network with uncertain links. We have derived a necessary condition for stochastic stability of the power network with the link uncertainty. The necessary condition is then used to rank order the contingencies. We have shown due to interaction between different uncertainties the ranking can substantially change. The state of the art N−kN-kN−k contingency analysis does not consider the possibility of interference between link uncertainties and rank the links according to the severity of N−1N-1N−1 contingencies. We have presented simulation results for New England 393939 bus system as a support of our claim.
Resilience‐based framework for switch placement problem in power distribution systems
IET Generation, Transmission & Distribution, 2018
Optimal placement of switches can play a key role in providing resilience to power distribution systems against major faults caused by natural disasters. This study presents a resilience-based framework for optimal switch placement in distribution systems being consistent with the expansion plans of distributed generation units. At first, the impact of hurricanes on distribution system components is modelled using the geographic information system of distribution grid and the strength of components against extreme weather-related events. Then, a new resiliency index is proposed to assess the resilience of distribution grids. This index is involved in a mathematical model of the switch placement problem and the obtained formulation is modelled as a mixed integer linear programming optimisation problem. The presented framework is implemented on two test systems, i.e. an illustrative test system and Bus 4 of the Roy Billinton test system. The results prove the effectiveness of this approach to improving the resiliency of distribution systems. D, N − 2 ratio of supplied load in different load points of islanding area located in downstream of lth faulted feeder section
A Multi-Objective Memetic Optimization Method for Power Network Cascading Failures Protection
Reliable and safe power grid operation requires the anticipation of cascading failures and the establishment of appropriate protection plans for their management. In this paper, we address this latter problem by line switching and propose a multi-objective memetic algorithm (MOMA), which combines the binary differential evolution algorithm with the non-dominated sorting mechanism and the Lamarckian local search. The 380 kV Italian power transmission network is used as a realistic test case.
Transmission System Reconfiguration to Reduce Losses and Cost Ensuring Voltage Security
The aim of this paper is to reduce the losses, total generation cost by switching of transmission line and to maintain voltage security under N − 1 contingency conditions. Generation cost is calculated and the priority list is made for switching the line. The problem is solved by ACOPF using Interior Point Method. In order to test the feasibility and effectiveness of the above method, a sample 6-bus system and IEEE 30-bus system have been used. The impact of switching on system parameter includes the generation cost, locational marginal pricing (LMP) and transmission losses, ensuring voltage security of the system. Keywords Transmission Switching (TS), AC Optimal Power Flow (ACOPF), N − 1 Contingency and Interior Point Method
Contingency Selection and Ranking Approach for Power Systems
International Journal of Computing and Digital Systems
In this paper, an efficient technique based on ranking lines and generators outage contingencies according to their severity has been developed. The technique is based on a defined performance index (PI). The elements of this PI are obtained by calculating the generators and lines, outages distributing factors instead of repeating the load flow analysis. Results for the Saudi Electric Company (SEC) in the central operating area have been obtained with the proposed technique and are compared with those obtained by the conventional ac-dc load flow methods.