Risk Assessment Of Power System Research Articles

Review on Risk Assessment of Power System

Abstract: With electric power system becoming more and more complex and intelligent these days, its uncertainty also increases. This paper classifies the references of the risk assessment on power system from the aspects of evaluation hierarchy, evaluation category, evaluation model, power system status, time and simulation algorithm. The purpose of this paper is to reveal the research status and compared the advantages and disadvantages of the methods used. And the future development of risk assessment on power system is also prospected.

Real-time Evaluation Model of Power Line Fault Probability based on Multiple Meteorological factors

In this paper we study the power line fault probability considering various meteorological factors. The calculation of the real-time fault probability of transmission lines is an important part of on-line risk assessment and real-time reliability calculation of power system. First, we study the fuzzy member function of various factors. Uncertainty theory is adopted to determine the weight coefficient of each layer, combined with fuzzy evaluation method. Second we collect actual data to simulate the model. The quantitative model of each monitoring quantity is established. Finally, We verified our model in actual weather data and power line malfunction probability data. The experimental results show that the proposed method is effective and promising in prevent such incident.

Wind Power System Risk Assessment Based on Fuzzy Clustering and Copula Function Modeling

According to the characteristics of the correlation of multiple wind farm output, this paper put forwards a modeling method based on fuzzy c-means clustering and the copula function, and correlation wind farms are inserted into IEEE-RTS79 reliability system for risk assessment. By the probabilistic load flow calculated by Monte Carlo simulation method, the probability of the accident is derived, and bus voltage and branch power flow overload risk index are defined in this paper. The results show that this method can realize the modeling of the correlation of wind power output, and the risk index can identify the weakness of the system, which can provide reference for the operation and maintenance personnel.

A Review of Risk Assessment Methods for Power System

In view of the current social background of power system becoming more and more complicated, and the current research situation of related fields, this paper discusses the common methods of power system risk assessment, including the method of hierarchy analysis, Markov chain model, Monte Carlo method, fuzzy comprehensive evaluation and related research progress. The advantages and disadvantages of the four methods are enumerated respectively. It is considered that the power system should be evaluated synthetically in the practical application and the effective risk assessment method should be adopted rationally.

Multihazard Risk Assessment of Electric Power Systems

AbstractElectric power systems are susceptible to damage due to natural hazards such as hurricanes and earthquakes. Considerable effort has been made to develop methodologies for assessing the reliability of electric power systems under a single hazard such as hurricanes or earthquakes. However, there are parts of the world, such as the coastal areas of South Carolina, which are affected by both hazards. In such regions, more comprehensive risk assessment can be achieved when the focus is shifted from single-hazard to multihazard analysis. There is, therefore, a need to develop methods for quantifying the risk posed by the combined effect of multiple hazards on structures and infrastructure systems in these regions. This paper presents a framework for multihazard risk assessment of electric power systems subjected to seismic and hurricane wind hazards. The framework includes hazard and structural component vulnerability models, system reliability analysis, and multihazard risk assessment. A notional elect...

Study on Security Risk Assessment of Power System Based on BP Neural Network

Study on Security Risk Assessment of Power System Based on BP Neural Network

Time‐varying failure rate simulation model of transmission lines and its application in power system risk assessment considering seasonal alternating meteorological disasters

Years of operation experience on power systems reveal that most transmission line fault events are related to seasonal alternating meteorological disasters, which have typical temporal and spatial distribution characteristics. However, power system risk assessment lacks basically accurate descriptions of failure rate time distribution for transmission lines. In this study, a method to calculate the time-varying failure rate of transmission lines in a monthly time scale is proposed to reflect the time-dependent fault regulation. However, the failure rate during any time interval cannot be derived directly from limited historical fault samples. Therefore, a simulation method of continuous time distribution function for failure rate is proposed, which adopts Fourier, Gaussian, and Weibull function assumptions. Furthermore, the parameters of these function hypotheses are fitted and compared using the fault samples of a province power grid and an urban power grid in China, respectively. Results show that the proposed simulation model is reasonable. Finally, the time-varying failure rate simulation model is adopted to quantify the risk of the verified IEEE-RBTS system. The risk indices also indicate that considering the time distribution characteristics of failure rate has a more significant influence on the system risk than the conventional methods.

Multi‐period probabilistic‐scenario risk assessment of power system in wind power uncertain environment

With the wind generation increasingly penetrating the power grids, there is a growing interest in developing new risk-based assessments for the grids security analysis. This study develops one kind of such risk tools to evaluate the security risks of power grids under certain amount of wind generation in a short period of time. First of all, a very short-term uncertainty model of wind generation is introduced. Then the conditional value-at-risk is used to design a safety distance (S-D), revealing the tail risks of operating states. Based on S-D, four new indices are defined to highlight the risks in a near future with considerable change of wind power output. The overall security assessment tool is compared with the conventional method both on a benchmark test system and a real power system in China. The results demonstrate the effectiveness and some advantages of this new risk-based tool.

Power System Risk Assessment in Cyber Attacks Considering the Role of Protection Systems

This paper presents a risk assessment method for evaluating the cyber security of power systems considering the role of protection systems. This paper considers the impact of bus and transmission line protection systems located in substations on the cyber-physical performance of power systems. The proposed method simulates the physical response of power systems to malicious attacks on protection system settings and parameters. The relationship among settings of protection devices, protection logics, and circuit breaker logics is analyzed. The expected load curtailment (ELC) index is used in this paper to quantify potential system losses due to cyber attacks. The Monte Carlo simulation is applied to calculate ELC for assessing attackers’ capabilities as bus arrangements are altered. The effectiveness of the proposed risk assessment method is demonstrated using a 9-bus system and the IEEE 68-bus system.

Wind speed modeling using a vector autoregressive process with a time-dependent intercept term

Abstract The effect of wind power on the electric power system is becoming increasingly important as more wind power is installed. This paper presents a Vector-Autoregressive-To-Anything (VARTA) process with a time-dependent intercept to model wind speeds in multiple locations. The model considers both temporal and spatial dependency structures in detail. It can be used in Monte Carlo simulations to assess the risk of very high or low wind speeds occurring in multiple locations at the same time and during consecutive hours. The long term simulation and short term forecasting results are assessed using measurements from 21 locations in Finland. A discussion on the applicability of the presented wind speed simulation method for the risk assessment of power systems is given.

Security risk assessment of cyber physical power system based on rough set and gene expression programming

Risk assessment is essential for the safe and reliable operation of cyber physical power system. Traditional security risk assessment methods do not take integration of cyber system and physical system of power grid into account. In order to solve this problem, security risk assessment algorithm of cyber physical power system based on rough set and gene expression programming is proposed. Firstly, fast attribution reduction based on binary search algorithm is presented. Secondly, security risk assessment function for cyber physical power system is mined based on gene expression programming. Lastly, security risk levels of cyber physical power system are predicted and analyzed by the above function model. Experimental results show that security risk assessment function model based on the proposed algorithm has high efficiency of function mining, accuracy of security risk level prediction and strong practicality.

Business Continuity and Disaster Management: Mitigating the Socioeconomic Impacts of Facility Downtime After a Disaster

Presidential Policy Directive 8 (PPD-8) was signed by U.S. President Barack Obama on 30 March 2011. This directive deals with the subject of developing a national preparedness system for security and resiliency for businesses to endure a disaster or catastrophe, which can be caused by anything from natural disasters to terrorism. The overall purpose of the directive is for the U.S. Department of Homeland Security (DHS) to help administer a program within the United States to analyze, mitigate, and recover from a disaster. Any downtime at a major petrochemical plant or refinery can have an enormous impact on the national economy. This article provides recommendations on how to perform risk assessments in general, how to perform a risk assessment of a petrochemical industry power system, how to develop an effective preventative program, and how to recover quickly from a disaster. The benefits of being well prepared are also addressed.

Transient Operation Risk Assessment of Power System with Wind Farm Integration Based on Dynamic Security Region

With continuous expansion of the grid, the power system structure is becoming more complicated, leading to more and more uncertainty of the system. Especially, the massive integration of wind power and other renewable energy to the grid brings more challenges. In this paper, by taking use of DSR (dynamic security region) and risk assessment theory, it proposed the transient risk index calculation and integrated analysis method for wind power integration system, which was able to give quantitative indicators of the system day-ahead scheduling plan. The efficiency and practicality of theories mentioned herein were verified by standard numerical examples.

Hierarchical Risk Assessment of Transmission System Considering the Influence of Active Distribution Network

In traditional distribution system, power flow was unidirectional; thus loads were usually aggregated into the substation as an equivalent constant bus in the original risk analysis of transmission system. Detail structures of the distribution system were absolutely ignored. However, distribution system is transformed from passive to active nowadays with more and more distributed generations (DGs) being integrated into it. So, distribution system not only can be considered as loads but also can be considered as virtual power plants to supply power to local loads and even to send power back to the transmission system sometimes. In this paper, a hierarchical method is presented to evaluate the impact of role changing of the distribution system in power system risk assessment. In the study, DGs can supply critical loads in distribution system through re-dispatching after some contingency happens. Discrete probability model is employed to simulate the intermittent output of DGs. Available supply capacity (ASC) is used as a general constraint to guarantee the security level of distribution system that needs high reliability. Also, an iterative calculation between transmission system and distribution network is adopted to derive the risk indices with considering detail structures of the active distribution network. Further, impact of some factors on system risk calculation, such as DGs' capacities, dispersions, locations, and component outage probabilities, are discussed. Finally, correctness and effectiveness of the proposed method are validated by a modified IEEE RTS and RBTS system.

Risk Assessment of Power System with Wind Farm Considering Weather Impacts

A method of risk assessment considering weather impacts was proposed for power system with wind power. Firstly, the mechanism of the weather affecting the risk of power system is analyzed, and then the component reliability model based on weather was illustrated. The transmission line model takes into account of the situation that the line may pass through a variety of climatic zones. Secondly, combine the above-mentioned model with the existing risk assessment methods, a new method was obtained. By using of the modified IEEE-RTS79 system with wind power, the feasibility and reasonableness of the proposed model and approach are verified. The results show that it is necessary to consider weather especially when the system is integrated with large-scale wind power or the system passes through zones with particularly higher probability of bad weather. Compared with the existing risk assessment methods, the proposed method is more in line with the actual system, and the assessment results are more reasonable.

(Operational Risk Assessment of Power System Including Large-Scale Wind Farms)

Chinese Abstract: 由于风能具有随机性、间歇性与波动性等特点，致使当大规模风电场接入电力系统后，会给系统造成 不可忽视的负面影响，从而给电网的安全稳定运行带来风险。本文基于运行风险评估框架理论体系，建立了相 应的运行风险评估指标体系，分别从局部级和系统级两个层面反映系统的短期运行风险水平。最后，基于 IEEE-RTS79 验证上述所建评估框架理论体系的正确性。English Abstract: Due to the randomness, intermittent and fluctuation characteristics of wind energy, the negative effects brought by large-scale wind farms when they are connected to the power system cannot be neglected. Large scale wind farm connected to power grid will bring operational risk to the grid. Based on the theoretical framework of operational risk assessment, this paper established the corresponding operational risk assessment index system, which reflects the system’s short-term level of the operational risk from the local and system level respectively. At last, the accuracy of the established assessment index system is proved based on the IEEE-RTS79 system.

Research on Foronline Short-Term Risk Assessment of Power System with Fast and Accurate Analysis Method Based on State Space Division

This paper proposed a state space division method to assess the online short-term risk of power system fast and accurately. This method divided all the possible operation system states into two mutually complementary subspaces according to the occurrence probability. In order to shorten the time-consuming, different method was used to calculate the risk of each subspace. Analytical method (AM) was used to calculate the risk of the first subspace comprised with the large occurrence probability states, which was identified using the Fast Sorting Technique (FST). System states that have a small occurrence probability comprised the second subspace, whose risk was calculated using Monte Carlo Simulation (MCS) combined with the adaptive importance sampling technique (AIST) and scattered sampling technique (SST). Through the case studies conducted on the MRTS, it is validated that the proposed method can assess the online short-term risk fast and accurately.

Risk Assessment of Power System under Typhoon Disaster

The paper focuses on the research of typhoon disaster and its influence on power system security. A typhoon disaster simulation model is established to track the average impact of a large number of typhoon simulations in Guangdong province in China. The main parameters in the typhoon model includes typhoon frequency, landing position, approach angle, translation velocity, central pressure difference, radius to maximum wind, decay rate, wind field profile, etc. Then the typhoon simulation and power system risk assessment as well as the system loss evaluation are linked together. The results can provide a potential reference for the government policy makers as well as the power system planners and runners for power system risk assessment, planning and operation.

Imprecise Risk Assessment of Power System

The incomplete probabilistic information can lead to imprecision. The traditional power system risk assessment can only deal with random information, but it cannot deal with the imprecise information. Interval Probability (IP) can reflect both randomness and imprecision. The risk assessment of power system based on IP is an effective method to deal with imprecision and can provide more useful information to the decision-makers. In the paper, the completeness degree of probabilistic information was depicted by IP. The nonlinear optimization models for imprecise risk assessment of generating system and composite generation-transmission system were established. And the genetic algorithm was used to obtain the upper and lower bound of reliability indices. Case study on revised IEEE-RTS79 and IEEE-RBTS system showed the rationality and equity of presented method.

Power System Risk Assessment Software Design under Impact of Disaster Conditions

With the Influence of disaster factor on power system reliability become more and more significant, traditional deterministic risk analysis method has been difficult to adapt to power system risk assessment in changing disaster conditions. This paper puts disaster factor into power system risk assessment, and use improved Monte Carlo method to analyze the risk of all possible states of the system. Combined with online short-term assessment technology, based on the integration of multiple data sources, it uses several typical risk indexes for power system risk assessment under the impact of disaster conditions, then shows power grid operation risk, security warning information and weakness information. The system has been applied to practical power system to verify its scientific and practical design.