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Motivated by applications to security and high efficiency, we propose an automated methodology for validating on low-level intermediate representations the results of a source-level static analysis. Our methodology relies on two main ingredients: a relative-safety checker, an instance of a relational verifier which proves that a program is "safer" than another, and a transformation of programs...
An offline optimal flexible load transfer strategy of more electric aircraft including operation mode and fault location of variable frequency starter generator is proposed, whose key innovation is to quantify variable operational safety margin using node voltage flexibility. Firstly, a series of scenes that show the fluctuation of load in different operation mode are generated through the Monte Carlo...
Since isolated microgrids, such as all-electric ships (AES), have limited generation and finite inertia, frequency and voltage violations are prone to happen in these microgrids. Therefore, it is necessary to have a power management framework for optimal scheduling of microgrids while achieving stable real-time operation. This paper introduces a novel multi-objective security constrained power management...
Load recovery is an important part of network reconfiguration that aims at reconfiguring a stable skeleton network and recovering electrical supply as quickly as possible following a blackout. Considering the load recovery strategy may affect a strategic decision for generator start-up and restoration path selection, it is necessary to comprehensively deal with above three aspects simultaneously,...
Energy-harvesting techniques for low-power embedded devices are opening up new opportunities for the design and optimization of security protocols for Green Wireless Sensor Networks. In this paper, we focus on scenarios where the energy resources of nodes in the network are heterogeneous, and propose a network-level solution that leverages the heterogeneity of harvesting capabilities to reduce the...
Distributed energy resources are shaping the future of power systems. Coordination of these geographically scattered resources motivates the need for adoption of distributed control strategies. This paper presents a fully distributed DC Corrective Security Constrained Optimal Power Flow (CSCOPF) for electricity networks in which the transmission lines are potentially instrumented with Distributed...
This paper presents a multi-objective optimization model based on DC power flow to maximize the active power steady-state security region whilst minimizing the total generation cost. The stochastic and fluctuant nature of wind power is incorporated into the model as well. Regarding the cost of wind power, the concepts involving opportunity costs of wind power shortage and surplus are introduced in...
This paper investigates the value of nodal information of power systems in real-time. It is a fact that real-time security assessment of the power system requires nodal scheduling information of generating units, however, the value of this information from a market aspect is seldom discussed. In other words, precise schedules help the system operator not only assess the system security, but also estimate...
Increasing consumer choices and market options in the power market necessitate a more resilient grid operation. Security level indication based on the desired risk index and thus a risk-based security constrained optimal power flow is described and simulated in this paper. It highlights the possibility of giving a choice of security level to a consumer area and also presents the computation of risk...
Security Constrained Optimal Power Flow (SCOPF) is becoming more important in the electrical power system especially in the present deregulated environment. This paper focuses on completely linearizing the complex non-linear SCOPF problem. The objective function is linearized using Piecewise linearization technique and the constraints are framed using linear sensitivity factors. DC power flow analysis...
In this paper, we investigate two decomposition methods for their convergence rate which are used to solve security constrained economic dispatch (SCED): 1) Lagrangian Relaxation (LR), and 2) Augmented Lagrangian Relaxation (ALR). First, the centralized SCED problem is posed for a 6-bus test network and then it is decomposed into subproblems using both of the methods. In order to model the tie-line...
Risk-based security indexes can be used as a constraint in OPF to determine the most economic generation dispatch while ensuring that the risk of power system operation stays below a given value. Existing approaches only limit the total risk, which can result in some system states having significantly higher values of risk compared to others. In this paper, a risk-constrained AC OPF that limits the...
System Protection Schemes (SPS) have the potential to greatly enhance the utilization of the network, often by automatically disconnecting generators in response to contingency events. However, malfunctions of such systems may expose the system to harmful blackouts. The operation of unreliable SPS is therefore subject to a cost-benefit balance between the benefits of increased system utilization and...
Probabilistic risk-based approaches to system security provide a quantitative measure to evaluate the security of system operation. However, incorporating the risk-based security index as a constraint into the optimal power flow problem results in a complex optimization problem, which is difficult to solve in a centralized manner for large-scale power systems. In this paper, the application of so-called...
Recent studies suggest that in medium and long terms, distributed solar photo-voltaic generator (SPVG) will become commercially so attractive that large-scale implementation of this type can be seen in many parts of the world. The increase in the amount of renewable energy will cause stability and security issues in power system. An effective method is used to find out the maximum allowable penetration...
The importance of wind power generation has risen in the last years so much as to be considered among the most important and affordable Renewable Energy Sources (RES) with a growing rate faster than other technologies. Nowadays, wind technology is looking at offshore installations, due to the both lack of land resources and environmentalist opposition. This requires new criteria to set out the appropriate...
Recent studies have shown that dynamic removal of transmission lines from operation ("Transmission Switching") can reduce costs associated with power system operation. Smart Grid systems introduce flexibility into the transmission network topology and enable co-optimization of generation and network topology. The optimal transmission switching (OTS) problem has been posed in on small test...
This paper presents big bang-big crunch (BB-BC) method for the optimization of preventive control action to enhance the dynamic security of the power system against transient instabilities. In the proposed approach, generation rescheduling is selected as a preventive control action and this control action is considered as a constrained optimization problems where the constraints are dynamic security...
This paper proposes security constrained economic power dispatch (SCED) of the generators using parallel artificial bee colony (PABC) algorithm for electricity markets. The proposed non-linear optimization problem considers simultaneous minimization of deviations from scheduled transactions and minimization of fuel cost of the generators. The problem is formulated as a constrained optimization problem...
CAPTCHA is a test that can, automatically, tell human and computer programmes apart. It is now almost a standard security technology, and has found widespread application on commercial websites. Robustness and usability are two fundamental aspects with CAPTCHA. The robustness of a text CAPTCHA is typically determined by the strength of its segmentation-resistance mechanism. The mechanism of Crowding...
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