Probabilistic-based overload estimation for real-time smart grid vulnerability assessment

Abstract

In recent years, important efforts to improve monitoring, protection and control of power systems have been explored. In this connection, several novel approaches for assessing vulnerability in real time have been developed. However, most of the work is commonly focused on tackling stability phenomena, while the possible overloads are often treated as negligible in real-time power system security. But sometimes, high electric post-contingency currents might provoke overloads which could increase the system vulnerability problem. This paper presents a novel method for assessing the possibility of fast post-contingency overloads using Statistical Distribution Factors (SDFs) that allow computing an Overload Index (OVI) in real time. First, Monte Carlo-based contingency analysis is performed to iteratively calculate ac Distribution Factors (ac-DFs). After, SDFs are defined by the mean and standard deviation of ac-DFs. These SDFs are then used together with principal component analysis (PCA) and support vector machine classifier (SVM-C) in order to structure a table-based real-time post-contingency overload estimation algorithm, which allow computing OVIs depending on the actual operating state and the type of contingency. The proposal is tested on the IEEE New England 39-bus test system. Results show the feasibility of the methodology in alerting about fast possible overloads. Index Terms--Monte Carlo, overload, principal component analysis, security, smart grid, support vector machine, vulnerability assessment.

Reactive Security for Smart Grids Using Models@run.time-Based Simulation and Reasoning

“…Since an electrical grid usually can maintain an overload for a few seconds or minutes [8] the reasoning engine has to react within this time range. The reasoning process consists of an electrical load prediction for a specific point of the grid (one smart meter).…”

Real-time adaptive load shedding based on probabilistic overload estimation

“…First, using the probabilistic models of input parameters based on a short-term operating scenario and via optimal power flow (OPF) computations, MCbased ac contingency analysis is performed to iteratively calculate ac-DFs. After, SDFs are defined by the mean of ac-DFs, considering two types of filters that permit improving the accuracy of SDFs [5]. For real-time implementation, these SDFs are then joined with an intelligent classifier (based on PCA and SVM-C) in order to structure a table-based postcontingency overload estimation algorithm, which allows computing OVIs depending on the pre-contingency operating state and the actual contingency.…”

“…These factors can be used to predict the possible overload of grid elements after the occurrence of a disturbance [4], [5], [8].…”

“…However, sometimes high electric post-contingency currents might provoke overloads which could increase the system security problem. So, a system can be stable following a contingency, yet insecure due to post-fault system conditions resulting in equipment overloads [5].…”

“…The present paper applies a novel methodology to estimate the possible overloads in real time based on statistical ac-DFs (SDFs), which has been firstly introduced by the authors in [5]. The results are then used in order to coordinate and trigger an adaptive load shedding (ALS) scheme that allows alleviating the possible overloaded lines and so avoiding the possibility of further cascading failures and system blackouts.…”