Contingency analysis of power system by using voltage and active power performance index
04 Jul 2016-pp 1-5
TL;DR: In this paper, all line outage contingencies in a standard 6 bus and 5 bus power system has been done in MATLAB environment and load flow analysis has been performed on the system and the active power and voltage performance indices have been calculated.
Abstract: Now a days power system protection is an important task for an operating engineer, which can be done by doing online security assessment. Contingency analysis is one of the best methods to forecast the condition of power system if any unwanted event occured in the power system. To do contingency analysis first the operator has to know the parameters like voltage, power and voltage angle at each and every bus by doing load flow analysis on the system. Newton Raphson method is the best load flow method as it gives accurate results in less time. In this paper all line outage contingencies in a standard 6 bus and 5 bus power system has been done in MATLAB environment. For each line outage contingency, load flow analysis has been done on the system and the active power and voltage performance indices have been calculated. These two performance indices will give the idea about the change in active power flow through the lines and voltages at the buses for a particular line outage. Summation of these two indices will give the performance index value through which ranking of severity will be given to the lines. And from the load flow results comparison has been done between low rank and high rank line outage contingencies. This contingency analysis helps the operational engineer to know which line outage is dangerous to the system and what prior action is to be taken to minimize the effect of that particular line outage.
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TL;DR: In this paper, the authors proposed a cybersecurity assessment approach designed to assess the cyberphysical security of electric power systems (EPS), taking into consideration the intermittent generation of RES, vulnerabilities introduced by microprocessor-based electronic information and operational technology (IT/OT) devices, and contingency analysis results.
Abstract: The integration of renewable energy sources (RES) is rapidly increasing in electric power systems (EPS). While the inclusion of intermittent RES coupled with the wide-scale deployment of communication and sensing devices is important towards a fully smart grid, it has also expanded the cyber-threat landscape, effectively making power systems vulnerable to cyberattacks. This article proposes a cybersecurity assessment approach designed to assess the cyberphysical security of EPS. The work takes into consideration the intermittent generation of RES, vulnerabilities introduced by microprocessor-based electronic information and operational technology (IT/OT) devices, and contingency analysis results. The proposed approach utilizes deep reinforcement learning (DRL) and an adapted Common Vulnerability Scoring System (CVSS) score tailored to assess vulnerabilities in EPS in order to identify the optimal attack transition policy based on $N-2$ contingency results, i.e., the simultaneous failure of two system elements. The effectiveness of the work is validated via numerical and real-time simulation experiments performed on literature-based power grid test cases. The results demonstrate how the proposed method based on deep $Q$ -network ( $\text{D}Q\text{N}$ ) performs closely to a graph-search approach in terms of the number of transitions needed to find the optimal attack policy, without the need for full observation of the system. In addition, the experiments present the method’s scalability by showcasing the number of transitions needed to find the optimal attack transition policy in a large system such as the Polish 2383 bus test system. The results exhibit how the proposed approach requires one order of magnitude fewer transitions when compared to a random transition policy.
37 citations
Posted Content•
06 Jul 2020TL;DR: A cybersecurity assessment approach designed to assess the cyberphysical security of EPS by utilizing deep reinforcement learning (DRL) and an adapted Common Vulnerability Scoring System (CVSS) score tailored to assess vulnerabilities in EPS to identify the optimal attack transition policy.
Abstract: The integration of renewable energy sources (RES) is rapidly increasing in electric power systems (EPS). While the inclusion of intermittent RES coupled with the wide-scale deployment of communication and sensing devices is important towards a fully smart grid, it has also expanded the cyber-threat landscape, effectively making power systems vulnerable to cyberattacks. This paper proposes a cybersecurity assessment approach designed to assess the cyberphysical security of EPS. The work takes into consideration the intermittent generation of RES, vulnerabilities introduced by microprocessor-based electronic information and operational technology (IT/OT) devices, and contingency analysis results. The proposed approach utilizes deep reinforcement learning (DRL) and an adapted Common Vulnerability Scoring System (CVSS) score tailored to assess vulnerabilities in EPS in order to identify the optimal attack transition policy based on N-2 contingency results, i.e., the simultaneous failure of two system elements. The effectiveness of the work is validated via numerical and real-time simulation experiments performed on literature-based power grid test cases. The results demonstrate how the proposed method based on deep Q-network (DQN) performs closely to a graph-search approach in terms of the number of transitions needed to find the optimal attack policy, without the need for full observation of the system. In addition, the experiments present the method's scalability by showcasing the number of transitions needed to find the optimal attack transition policy in a large system such as the Polish 2383 bus test system. The results exhibit how the proposed approach requires one order of magnitude fewer transitions when compared to a random transition policy.
20 citations
Cites background from "Contingency analysis of power syste..."
...Other efforts compute the active power flow change at lines and the voltage change at buses to evaluate the severity of N − 1 and N − 2 contingencies [18]....
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18 May 2018
TL;DR: In this paper, contingency analysis has been done for an IEEE 30 bus system, outage of generators, transmission lines and transformers have been carried out, and results are analysed.
Abstract: Contingency analysis is significant for power system protection. It is the analysis of a power system during non-functionality of equipment(s) or device(s). Contingencies in a power system can occur due to internal component failures or due to external factors like lightning and overloading of equipment. In this paper, contingency analysis has been done for an IEEE 30 bus system. Outage of generators, transmission lines and transformers have been carried out and the results are analysed. Under transmission line contingency, single line outage, double line outage and single circuit line with a compensator outage has been performed. Load flow before and after the contingency have been analysed using PSAT software. Performance indices have been used to rank the severity of each component's contingency. Performance index is given by the sum of active power performance index and voltage performance index. Similarly, a parameter known as Severity index is used to evaluate the effect on all transmissions lines in the power system due to outage of each component.
11 citations
Cites background from "Contingency analysis of power syste..."
...Sum of these two indices gives the performance index through which, ranking can be done [4]....
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19 Mar 2018
TL;DR: A Newton-Raphson load flow based approach is presented to perform contingency ranking by computing a voltage performance index (PI), which is classified in secure, insecure and critical classes and then the method proceeds in the decreased order of severity to rank them based on the PI value.
Abstract: The security assessment is a fundamental task as it provides the knowledge about the system status in case of contingency. This helps in rapidly take the accurate action to maintain the system secure. In the present work, a Newton-Raphson load flow based approach is presented to perform contingency ranking by computing a voltage performance index (PI). The contingencies are classified in secure, insecure and critical classes and then the method proceeds in the decreased order of severity to rank them based on the PI value. The proposed method is applied to the IEEE 39-bus system in MATLAB environment by considering (N-1) contingency for different load conditions.
10 citations
Cites methods from "Contingency analysis of power syste..."
...Similarly, this method is used in [14] for the classification of line outage cases using two different test systems....
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TL;DR: Based on the load flow results and performance indexes, the Ethiopian Electric Power (EEP) North-West region network is recommended for an upgrade or the reactive power or series compensators should be constructed on the riskiest lines and substations.
Abstract: In recent years, power systems have been pushed to operate above their limits due to the increase in the demand for energy supply and its usage. This increase is accompanied by various kinds of obstructions in power transmission systems. A power system is said to be secured when it is free from danger or risk. Power systems security deals with the ability of the system to withstand any contingencies without any consequences. Contingencies are potentially harmful disturbances which occur during the steady state operation of a power system. Load flow constitutes the most important study in a power system for planning, operation, and expansion. Contingency selection is performed by calculating two kinds of performance indices; an active performance index (PIP) and reactive power performance index (PIV) for a single transmission line outage. In this paper, with the help of the Newton Raphson method, the PIP and PIV were calculated with DIgSILENT Power Factory simulation software and contingency ranking was performed. Based on the load flow results and performance indexes, the Ethiopian Electric Power (EEP) North-West region network is recommended for an upgrade or the reactive power or series compensators should be constructed on the riskiest lines and substations.
10 citations
Cites background from "Contingency analysis of power syste..."
...These are the: active power performance index (PIP) and reactive power performance index (PIV) [12]....
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...Another performance index parameter, which is used, is the reactive power performance index corresponding to bus voltage magnitude violations, PIV....
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...This is mathematically given as: PIV = Npq∑ i=1 [ 2 (Vi − Vinom) Vi max − Vi min ]2 , (8) where: Vi is the voltage of bus i, Vi max and Vi min are the maximum and minimum voltage limits, Vinom is the average of voltages Vi max and Vi min, and Npq is the total number of load buses in the system....
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...5 suggest that the severity rank is directly proportional to the PIV value of the line....
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...This table also clearly displays the PIP and PIV values with security/contingency severity ranking based on the PIV values of the lines....
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References
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Book•
01 Jan 1984
TL;DR: In this paper, the authors present a graduate-level text in electric power engineering as regards to planning, operating, and controlling large scale power generation and transmission systems, including characteristics of power generation units, transmission losses, generation with limited energy supply, control of generation, and power system security.
Abstract: Topics considered include characteristics of power generation units, transmission losses, generation with limited energy supply, control of generation, and power system security. This book is a graduate-level text in electric power engineering as regards to planning, operating, and controlling large scale power generation and transmission systems. Material used was generated in the post-1966 period. Many (if not most) of the chapter problems require a digital computer. A background in steady-state power circuit analysis is required.
6,344 citations
"Contingency analysis of power syste..." refers background in this paper
...Many work has been done on contingency selection mainly, whose aim is to reduce the indigenous long list of contingencies by selecting only the outages with severe limit violations [5]....
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01 Dec 1987
TL;DR: This paper reviews present formulations and methods, and tries to point out areas of difficulty that constitute the main challenges for successful practical on-line implementations over the coming years.
Abstract: An operationally "secure" power system is one with low probability of blackout or equipment damage. The power system control processes needed to maintain a designated security level at minimum operating cost are extremely complicated. They increasingly depend upon on-line computer security analysis and optimization. This on-line technology is still relatively new, with enormous further potential. Since security and optimality are normally conflicting requirements of power system control, it is inappropriate to treat them separately. Therefore, they are slowly becoming coalesced into a unified hierarchical mathematical problem formulation: one that is, however, far too complex to afford anything but an approximate, near-optimal solution. The practical validity of this unifying trend relies on being able to incorporate all significant security constraints within the process. The main two current computational tools in this field are contingency analysis and special operations-oriented versions of optimal power flow (OPF). Contingency analysis identifies potential emergencies through extensive "what if?." simulations on the power system network. OPF is a major extension to the conventional dispatch calculation. It can respect system static security limits, and can schedule reactive as well as active power. Moreover, the advanced versions of OPF include or interface with contingency analysis. This paper reviews present formulations and methods, and tries to point out areas of difficulty that constitute the main challenges for successful practical on-line implementations over the coming years.
533 citations
TL;DR: A fast technique has been developed for the automatic ranking and selection of contingency cases for a power system contingency analysis study and results of this technique applied to different test systems are presented.
Abstract: A fast technique has been developed for the automatic ranking and selection of contingency cases for a power system contingency analysis study. A contingency list is built containing line and generator outages which are ranked according to their expected severity as reflected in voltage level degradation and circuit overloads. An adaptive contingency processorcan be set up by performing sequential contingency tests starting with the most severe contingencies at the top of the list and proceeding down the list, stopping when the severity goes below a threshold. Computational results of this technique applied to different test systems are presented.
466 citations
TL;DR: The need for ongoing research in power system control and for a concerted effort to develop an approach to system planning, design, and operation that properly recognizes all the system operating states and the state-transition mechanisms is emphasized as discussed by the authors.
Abstract: Power system control objectives for various levels and types of emergencies, e.g., overloads, faults, frequency drop, equipment damage, control system failure, are defined. Normal system operation, emergency prevention, emergency control, and recovery from emergencies are discussed. The need for ongoing research in power system control and for a concerted effort to develop an approach to system planning, design, and operation that properly recognizes all the system operating states and the state-transition mechanisms is emphasized. (LCL)
276 citations
TL;DR: A fast method for evaluating contingencies either in real time in an actual emergency or for security monitoring is introduced, which begins with treating the system or a piece of it as electrically rigid and gradually relaxing the results tier by tier to account for the actual flexibility of the transmission.
Abstract: A fast method for evaluating contingencies either in real time in an actual emergency or for security monitoring is introduced. This method begins with treating the system or a piece of it (a float) as electrically rigid and then gradually relaxing the results tier by tier to account for the actual flexibility of the transmission. The diagonally dominant or dispersive nature of the power system is utilized. Speed of computation is derived from this exploitation of the structure of the problem which also allows explicit solutions for the intermediate steps. Solutions can be obtained in the vicinity of the contingency or at secondary sites like weak cutsets within the system. Computer illustrations of the method are provided and the convergence of the proposed algorithms is proven. No "equivalent" network is used.
157 citations