Abstract
The operation and structure of the power system are becoming increasingly complex, and the probability of cascading fault increases. To this end, this paper proposes a cascading fault preventive control strategy that considers safety and the economy. First is to give a mathematical form to discriminate the cascading fault according to the action characteristics of the current-type backup protection. Second, the safety and economy of the system are evaluated in terms of power grid safety margin and generation operation cost, respectively, the initial faults are selected based on the power grid vulnerability and safety margin, and a cascading fault preventive control model is constructed for different initial faults’ scenarios. The model is a two-layer optimization mathematical model, with the inner model being solved by particle swarm optimization to minimize the power grid safety margin. The outer model is solved by the multiobjective algorithm to minimize generation cost and maximizing power grid safety margin. Finally, the calculated Pareto set is evaluated using fuzzy set theory to determine the optimal generator output strategy. The feasibility of the proposed method is verified by conducting a simulation study with the IEEE39 node system as an example.
Highlights
Mathematical Expression of Cascading FaultIn the event of a blackout, the cascading fault of the power grid is usually caused by the backup protection action caused by the power flow transfer, which usually occurs in the early stage of the blackout
Academic Editor: Yang Li e operation and structure of the power system are becoming increasingly complex, and the probability of cascading fault increases
The safety and economy of the system are evaluated in terms of power grid safety margin and generation operation cost, respectively, the initial faults are selected based on the power grid vulnerability and safety margin, and a cascading fault preventive control model is constructed for different initial faults’ scenarios. e model is a two-layer optimization mathematical model, with the inner model being solved by particle swarm optimization to minimize the power grid safety margin
Summary
In the event of a blackout, the cascading fault of the power grid is usually caused by the backup protection action caused by the power flow transfer, which usually occurs in the early stage of the blackout. This paper mainly studies a common cascading fault mode: after the initial fault branch is cut off, with the power flow transfer, the cascading fault occurs due to the corresponding electrical quantity of the remaining branches entering the action area of the backup protection (mainly current protection and distance protection (Section 3)). Considering all the remaining branches, we can further give the expression shown in the following formula: It can be seen from formula (2) that, from the power grid level, when I < 0, the power grid is in the cascading fault state, when I > 0, the power grid is in the safe state, and when I 0, the power grid is just in the critical state of cascading fault. In this way, according to formula (2), the mathematical expression for judging the cascading fault of the power grid is given
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