Vulnerability Assessment Of Power Grid Research Articles

Comparison of different power flow techniques for power grid vulnerability assessment against symmetrical faults using bus impedance matrix

Due to the widespread proliferation of distributed generation resources and the current market situation, ensuring the security and reliability of power grids against fault events has become a more challenging task. The aim of this paper is to compare different power flow techniques for power grid vulnerability assessment against symmetrical fault incidents using bus impedance matrix. In this study, first, the relationship of the post-fault voltage phasor at each bus with the pre-fault voltage phasors at that bus and the faulted bus, impedance matrix elements, and fault impedance is investigated through power system analysis under pre-fault and post-fault circumstances. Subsequently, the accuracy of different iterative and non-iterative power flow algorithms, i.e. Newton Raphson (NR), Fast Decoupled (FD), and Direct Current (DC) methods, for the power grid vulnerability assessment is compared. To achieve this, the fault analysis at each bus is performed commencing with a very large fault impedance and ending with the fault impedance at which one of the buses reaches the low voltage violation limit. Finally, to appraise the proposed strategy, several simulations have been undertaken on IEEE 14 bus system using MATLAB software. The simulation results indicate that the power grid vulnerability against symmetrical faults is highly influenced by the type of applied power flow technique.

Vulnerability Assessment of Power Grids Against Cost-Constrained Hybrid Attacks

The frequent occurrences of cascading failures in power grids have been receiving continuous attention in recent years. An urgent task for us is to assess the vulnerability of power grids against various kinds of attacks, which trigger cascading failures. In this brief, we formulate a cost-constrained hybrid attack in power grids, where both nodes and links are targeted with a limited total attack cost. Based on the consequence and cost of removing a component (node or link), we propose an attack centrality metric for components, which can be either local or global depending on the depth of cascading failures. We further propose a greedy hybrid attack and another optimal hybrid attack by applying the attack centrality. Simulation results on IEEE bus test data demonstrate that the optimal attack is more efficient than the greedy one. Furthermore, we find, counterintuitively, that the local centrality based attack algorithms perform better than the global centrality based ones when attack cost is a concern. Our work can help in the robustness optimization of power systems by revealing the worst-case attack vulnerability and most vulnerable components.

Vulnerability Assessment of Power Grids Against Link-Based Attacks

In modern power grids, a local failure or attack can trigger catastrophic cascading failures, which makes it challenging to assess the attack vulnerability of power grids. In this brief, we define the optimal $K$ -link attack problem and study the attack vulnerability of power grids in cascading failures. We propose a link centrality measure based on both topological and electrical properties for power grids. According to this centrality measure, we propose a greedy attack algorithm and an optimal attack algorithm. Simulation results based on standard IEEE bus test data show that the optimal attack is better than the greedy attack and the traditional PSO-based attack in fracturing power grids. Moreover, the greedy attack has an adequate attack efficiency with a smaller computational cost. This brief aids in understanding the vulnerability of power grids and provides clues for securing power grids.

Comprehensive vulnerability assessment method for nodes considering anti-interference ability and influence

The vulnerability assessment of power grid is of great significance in the current research. Power system faces many kinds of uncertainty factors, and the disturbance caused by them has become one of the main factors which restrict the safe operation of power grid. To solve this problem, considering the anti-interference ability of the system when the system is disturbed and the effect of the system when the node is out of operation, a set of index to reflect the anti-interference ability and the influence of nodes are set up. On this basis, a new comprehensive vulnerability assessment method of nodes is put forward by using super efficiency data envelopment analysis to scientific integration. Finally, the simulative results of IEEE30-bus system indicated that the proposed model is rational and valid.

Assessment of power grid vulnerabilities accounting for stochastic loads and model imprecision

Vulnerability and robustness are major concerns for future power grids. Malicious attacks and extreme weather conditions have the potential to trigger multiple components outages, cascading failures and large blackouts. Robust contingency identification procedures are necessary to improve power grids resilience and identify critical scenarios. This paper proposes a framework for advanced uncertainty quantification and vulnerability assessment of power grids. The framework allows critical failure scenarios to be identified and overcomes the limitations of current approaches by explicitly considering aleatory and epistemic sources of uncertainty modelled using probability boxes. The different effects of stochastic fluctuation of the power demand, imprecision in power grid parameters and uncertainty in the selection of the vulnerability model have been quantified. Spectral graph metrics for vulnerability are computed using different weights and are compared to power-flow-based cascading indices in ranking N-1 line failures and random N-k lines attacks. A rank correlation test is proposed for further comparison of the vulnerability metrics. The IEEE 24 nodes reliability test power network is selected as a representative case study and a detailed discussion of the results and findings is presented.

A study of the impacts of flow direction and electrical constraints on vulnerability assessment of power grid using electrical betweenness measures

Abstract In this paper, we analyze the impacts of major electrical properties, including node constraints, line limits, and flow direction, on vulnerability assessment of power grid using several types of electrical betweenness measures. Specifically, we first propose a set of new electrical betweenness measures, which takes into account flow direction in power grids. Then, the impacts of major electrical properties on vulnerability assessment of power grid are analyzed by comparing the identification results of critical components based on the proposed electrical betweenness measures with those based on the other two types of electrical betweenness measures reported in the literature, which take into consideration node constraints and line limits, respectively. Analysis results show the important impact of flow direction on the identification of critical components. The results lead us to introduce a set of combined electrical betweenness measures that take into account node constraints, line limits, and flow direction together. Simulation results on the IEEE 300-bus system and the Italian power grid show that the combined electrical betweenness measures are superior in identifying critical components and more useful in assessing power grid vulnerability.

Analysis of Power Grid Vulnerability Based on Electrical Dissection Method

As the power grid blackout accidents occur frequently, the vulnerability analysis becomes an important topic in power system analysis. A new electrical dissection method for the power grid vulnerability assessment is presented in this paper. The method can effectively reflect the power transmission between generator and load on the terminal of each line, and quantify the using relationship with the branch transmission power limit. An IEEE 39-bus text system was used to testify this method and the results indicated the methods efficiency and rationality. This paper is supported by NSFC 51307019.

An electrical betweenness approach for vulnerability assessment of power grids considering the capacity of generators and load

Most existing research on the vulnerability of power grids based on complex networks ignores the electrical characteristics and the capacity of generators and load. In this paper, the electrical betweenness is defined by considering the maximal demand of load and the capacity of generators in power grids. The loss of load, which reflects the ability of power grids to provide sufficient power to customers, is introduced to measure the vulnerability together with the size of the largest cluster. The simulation results of the IEEE-118 bus system and the Central China Power Grid show that the cumulative distributions of node electrical betweenness follow a power-law and that the nodes with high electrical betweenness play critical roles in both topological structure and power transmission of power grids. The results prove that the model proposed in this paper is effective for analyzing the vulnerability of power grids.

Vulnerability Assessment of Power Grid Using Graph Topological Indices

This paper presents an assessment of the vulnerability of the power grid to blackout using graph topological indexes. Based on a FERC 715 report and the outage reports, the cascading faults of summer WSCC 1996 are reconstructed, and the graphical property of the grid is compared between two cases: when the blackout triggering lines are removed simulating the actual sequence of cascading outages and when the same number of randomly selected lines are removed. The investigation finds that the critical path lengths of the triggering events of the July and August outages of 1996 WSCC blackout are higher than those of no-outage and arbitrary events. In addition, the small world-ness index for each of the outage triggering events is much smaller than that of normal or any no-outage scenario, indicating that events of shifting a network from small world to a random network would be more likely cascaded to wide area outage.