Introduction to the Complex Systems Security and Reliability Mini-Track

This is the first year of the new Track on Complex Systems. No doubt the idea of what a complex system is will be different to different people. For the purpose of this Track, a complex system may be large or small in scale. An important characteristic, however, is that such a system exhibiting a behavior under stress that is difficult to predict. This may be because models are not well understood (i.e. load models in electric power systems, behavioral models in social and economic systems). It may be because the number of variables is so large that it is beyond simulation capabilities of current computers, or because the relation between a large number of variables is so complex that current mathematics or simulation methods are inadequate. This track seeks to explore methods at the frontier of understanding complex system phenomena and the electric power system is a worthy example of such a system.There are five mini-tracks in this Track. The mini-track on Information Management seeks to explore techniques for managing and visualizing large-scale models that may be distributed across multiple operating authorities. Papers that cover both distribution and transmission network applications are scheduled for presentation.Another Mini-track focuses on topics related to the ability of complex systems such as power systems to survive disturbances with minimal impact on performance. Specific topics to be presented are steady state and dynamic security assessment where the impacts of pre-specified contingencies are analyzed and Available Transfer Capability (ATC), which quantifies the ability of the interconnected system to accept increases in power, transfers.Many large complex systems exhibit evidence of self-organized criticality. Issues such as the role of network size and topology along with the influence of network loading and operation on self-organized criticality are of interest. Evidence that large network disturbances are of a self-organized type and mechanisms of self-organized behavior in large networks are to be presented.Hybrid systems can be viewed as systems that allow interactions between discrete events and continuous dynamics. As such, they are natural models for complex interactive networks and systems such as manufacturing, power, communications, and transportation systems. A satisfactory theory for such systems, which draws from several disciplines including control theory, computer science, and applied mathematics, will have an enormous impact on the design, synthesis, and operations of many practical systems. Computational and algorithmic approaches to such problems encounter considerable difficulties. In addition to modeling and analysis of such systems, this mini-track explores novel computational paradigms that are able to accommodate uncertainties in the system at various levels.Finally, there are three sessions in the mini-track on Markets and Economics. The aim of this mini-track is to explore the ability of commercial trading models to effectively represent the complex physical behavior of an electricity industry, an issue that is critical to the success of electricity industry restructuring. Important aspects of this issue include the design of efficient spot markets and ancillary service markets, and mechanisms to incorporate network effects in electricity trading models. Papers will be presented that address these and other aspects of this important problem.

There are five mini-tracks in this Track. One minitrack consisting of eight papers in two sessions focuses on Robust and Resilient Critical Infrastructure Systems such as transportation systems, communication networks, and electric power grids. These systems contain interactive subsystems of continuous-time dynamics, discrete-time events, continuous-time controllers, and discrete-time event controllers. Such systems are characterized by complex nonlinear behavior, and experience uncertainty both in their internal description and in external disturbances/environments. The design, analysis and survivability of such infrastructures present many analytical and computational challenges. The Mini-track on “Information Management and Visualization” seeks to explore techniques for managing and visualizing large-scale models that may be distributed across multiple operating authorities. Data issues are prominently featured in this minitrack. Other papers cover shipboard power systems and ways to visualize market prices in network applications are scheduled for presentation. Another Minitrack focuses on topics related to the ability of complex systems such as power systems to survive disturbances with minimal impact on performance. This Minitrack in entitled “Security and Reliability”. Specific topics to be presented are steady-state and dynamic security assessment where the impacts of pre-specified contingencies are analyzed and Available Transfer Capability (ATC) which quantifies the ability of the interconnected system to accept increases in power transfers. Many large complex systems exhibit evidence of self-organized criticality. Issues such as the role of network size and topology along with the influence of network loading and operation on selforganized criticality are of interest. Evidence that large network disturbances are of a selforganized type and mechanisms of self-organized behavior in large networks are to be presented. Finally, there are two sessions in the mini-track on Electricity Markets and Regulation. The aim of this mini-track is to explore the ability of commercial trading models to effectively represent the complex physical behavior of an electricity industry, an issue that is critical to the success of electricity industry restructuring. Important aspects of this issue include the design of efficient spot markets and ancillary service markets, and mechanisms to incorporate network effects in electricity trading models. Papers will be presented that address these and other aspects of this important problem.

This minitrack focuses on topics related to the monitoring and control of complex systems such as power systems to ensure that disturbances have a minimal impact on performance. Specific topics include: Steady-State and Dynamic Security Assessment, Available Transfer Capability (ATC), State Estimation, Security-Constrained Optimal Power Flow, Sensor Applications, Large-Scale Real-Time Control, and related technologies. The sessions in this minitrack are typically organized around current research areas in electric power systems monitoring and control. This year's themes include Infrastructure and Architecture, and Monitoring and Control.

This mini-track is part of the Complex Systems track. It focuses on topics related to the ability of complex systems such as power systems to survive disturbances with minimal impact on performance. Specific topics include: Modeling and simulation, Steady-State and Dynamic Security Assessment; Available Transfer Capability (ATC); State Estimation; Security-Constrained Optimal Power Flow; Sensor Applications; Large-Scale Real-Time Control; and related technologies. Included in this is the issue of voltage stability, modeling and analysis of failure propagation, and nonlinear control. This year’s papers focus specifically on monitoring and model verification, visualization, operation under multiple objectives, fast contingency analysis, automated fault diagnosis, substation data processing for decision making, and interdependence in fuel supplies and the power system. The papers are particularly relevant after the August 14, 2003 blackout which has drawn considerable attention to the subjects of monitoring, control, and analysis of large electric power grids. The paper by Apostolov is concerned with the verification of models used in security assessment. The paper by Meliopoulos, Cokkinides, and Overbye looks at visualization techniques using realtime power flow data. The paper by McArthur, Davidson, Hossack and McDonald reports on automating power system fault diagnosis through multi-agent system technology. The paper by Kezunovic and Taylor proposes a new solution to substation sensing and decision making issues. The paper by Begovic, Radibratovic, Lambert and Novosel looks at the issues of reactive power in the operation of a large system where optimization requires several objectives. The paper by Venkatasubramanian, Kavasseri, and Lu reports on a new method to monitor generator dynamic states in real time. The paper by Carullo, Olaleye and Nwankpa proposes a bold new approach to contingency analysis using dedicated VLSI components. The paper by Fedora considers the interdependency between fuel systems and the electrical system.

This minitrack focuses on topics related to the monitoring and control of complex systems such as power systems to ensure that disturbances have a minimal impact on performance. Specific topics include: steady-state and dynamic security assessment where the impacts of pre-specified contingencies are analyzed; Available Transfer Capability (ATC) which quantifies the ability of the interconnected system to accept increases in power transfers; widearea measurement technologies, state estimation, and the investigation of new realtime control strategies.

In practical power markets, Available Transfer Capability (ATC) is crucial for transmission customers, system operators and power marketers to make a good choice. It is an indication of the expected transfer capability remaining on the transmission network. In order to assure the secure, economic, stable and reliable operation of power systems, the assessment of ATC should be carried out instantly. Most of the existing ATC calculation are mainly focused on AC power systems and based on deterministic techniques. As high performance computing has been extensively used in scientific computation and technology, less work has been done on evaluation of ATC by using parallel algorithm. This paper is dealing with the evaluation of ATC by stochastic parallel algorithm in an AC power system. Due to the stochastic nature of power system behaviors, it is important to assess ATC from a statistical and risk analysis point of view. Considering the dynamics, time-varying and uncertainties of power systems, several statistical indices is presented to evaluate ATC. They are calculated based on Monte Carlo simulation and parallel computing. The system operation states can be simulated by Monte Carlo method, and the parallel algorithm based on MATPOWER (A MATLAB™ Power System Simulation Package) is developed. Case study with an IEEE 30-bus power system is used to verify the presented approach. Five-number summary and other statistical indices of ATC are calculated. The results show that the proposed method can elapse shorter computation time and it is more effective and practical. Some new attractive issues are suggested at the end.

Available transfer capability (ATC) is defined as a measure of the system's capability for transfers of power for further commercial activity, over and above already committed uses. In practical power markets, ATC can provide important information for transmission customers, system operators and power marketers. The assessment of ATC should be carried out to assure the secure, economic, stable and reliable operation of power systems. Most of the existing ATC calculation are mainly focused on AC power system and based on deterministic techniques. As high voltage direct current (HVDC) power distribution systems have been extensively used in modem transmission network, less work has been done on evaluation of ATC in AC-DC hybrid power system. This paper is dealing with the evaluation of ATC for the integration of HVDC link with an AC power system. The mathematical model of ATC for AC-DC hybrid power system is proposed. Due to the stochastic nature of power system behaviors, it is important to assess ATC from a statistical and risk analysis point of view. Considering the dynamics, time-varying and uncertainties of hybrid power systems, several statistical indices are presented to evaluate ATC and they are calculated based on Monte Carlo simulation. States of system operation can be simulated, and the algorithm based on MATPOWER (A MATLAB™ Power System Simulation Package) is developed in the environment of MATLAB 7.5. Case study with a modified IEEE 30-bus AC-DC hybrid power system is used to verify the presented approach. Sequential solution method is employed to deal with the AC-DC power flow. Five-number summary and other statistical indices of ATC are calculated. The results show that the proposed method is effective and practical. The research achievements are undergoing to transfer to the application in other hybrid power systems with different control style, and some new problems are suggested at the end of paper.

Available transfer capability (ATC) refers to the reliable power transfer capability for further commercial activities in the system based on current protocols. Traditional ATC method such as continuation power flow (CPF) can calculate ATC only based on a specific direction of load and generator, optimal power flow (OPF) cannot acquire accurate value of the intermediate calculations and have difficulty taking power system stability into account. Here, a novel ATC analysis method of AC–DC power system based on security region was proposed. First, the static security region (SSR) of AC–DC power system considering stability and security constraints of AC–DC power systems and adjustment of HVDC control were presented. An ATC analysis method of AC–DC power system based on security region was then presented. A comparison between ATC based on security region and traditional method was made. Security region under different HVDC controls and its influence on ATC was analysed. Case studies indicated that the method proposed here can acquire optimal generation direction, the adjustment process of HVDC control and the ATC of AC–DC power system, providing reference for power system dispatch and operation.

This paper calculates total transfer capability (TTC) and available transfer capability (ATC) in different contingency conditions such as line outage and generator outage conditions. The most common continuous power flow method is utilised for TTC calculations. These calculations are useful for power wheeling in different power systems for power trading purposes in deregulated power systems. The methods are implemented for an Indian 62 bus power system considering three other outage conditions arbitrarily.

Determination of available transfer capability (ATC) requires the use of experience, intuition and exact judgment in order to meet several significant aspects in the deregulated environment. Based on these points, this paper proposes two heuristic approaches to compute ATC. The first proposed heuristic algorithm integrates the five methods known as continuation repeated power flow, repeated optimal power flow, radial basis function neural network, back propagation neural network and adaptive neuro fuzzy inference system to obtain ATC. The second proposed heuristic model is used to obtain multiple ATC values. Out of these, a specific ATC value will be selected based on a number of social, economic, deregulated environmental constraints and related to specific applications like optimization, on-line monitoring, and ATC forecasting known as multi-objective decision based optimal ATC. The validity of results obtained through these proposed methods are scrupulously verified on various buses of the IEEE 24-bus reliable test system. The results presented and derived conclusions in this paper are very useful for planning, operation, maintaining of reliable power in any power system and its monitoring in an on-line environment of deregulated power system. In this way, the proposed heuristic methods would contribute the best possible approach to assess multiple objective ATC using integrated methods.

A streamlined and enhanced iterative method for analysing power system available transfer capability and security

In this paper the use of TCSC and SVC to maximize Available Transfer Capability (ATC) generally defined as the maximum power transfer transaction between a specific power-seller and a power-buyer in a network during normal and contingency cases. In this paper, ATC is computed using Continuous Power Flow (CPF) method considering both line thermal limit as well as bus voltage limits. Real-code Genetic Algorithm is used as the optimization tool to determine the location as well as the controlling parameter of TCSC or SVC simultaneously. The performance of the Real-code Genetic Algorithm has been tested on IEEE 24-Bus Reliability Test System. Improving of ATC is an important issue in the current de-regulated environment of power systems. The Available Transfer Capability (ATC) of a transmission network is the unutilized transfer capabilities of a transmission network for the transfer of power for further commercial activity, over and above already committed usage. Power transactions between a specific seller bus/area and a buyer bus/area can be committed only when sufficient ATC is available. ATC can be limited usually by heavily loaded circuits and buses with relatively low voltages. It is well known that FACTS technology can control voltage magnitude, phase angle and circuit reactance. Using these devices may redistribute the load flow, regulating bus voltages. Therefore, it is worthwhile to investigate the impact of FACTS controllers on the ATC.

In deregulated market, available transfer capability (ATC) is a market signal refers to the capability of a system to transport above already subscribed transmission uses. It can provide significant information for power market participants. This paper deals with the evaluation of ATC for the integration of HVDC link with an AC power system. The computational model of ATC for AC-DC transmission system is formulated. Some numerical characteristics of ATC are estimated by robust statistic based on Monte Carlo simulations. The optimal power flow model is added into the repeated power flow method to consider both safe and economical operation. Sequential solution method is employed to deal with the AC-DC power flow. Case study with a modified IEEE 14-bus AC-DC transmission system is used and the program compiled based on MATPOWER in MATLAB R2008a. Several robust estimates of ATC indices are calculated. Comparison with the sample moments verifies the proposed method.

In distribution systems, it is important to guarantee the protected operating state of the power system by the transmission suppliers. To transmit a secure, dependable and economical supply of electric power, long separation bulk power transmission is fundamental. Despite that, the power transfer capacity of the power system is constrained because of the elements like thermal limits, voltage limits and security limits. Crow Search Optimizations (CSO) have been exhibited to be reasonable methodologies in taking care of nonlinear power system issues with Available Transfer Capability (ATC). It is conceivable to improve transmission capabilities. This proposed method based on the IEEE 30-bus system is considered with two distinct areas, and furthermore, the input source is a typical load system with a distributed network. There is a need to control the reactive power flow at the Point of Common Coupling (PCC) between the grids of various voltage levels. To operate a power system securely and furthermore to acquire the benefit of bulk power transfer, ATC evaluation is required. The load gets raised from 50% to 100% in the distribution side by including the thermal power plant (85% and 95% load is included) and with the procured condition, ATC and losses are to be determined. This ATC is determined for verified power supply to the consumers.

Available Transfer Capability (ATC) is a measure for transmission system security margin in open access electricity market. Determining the Available Transfer Capability (ATC) of the transmission networks, Repeated Power Flow (RPF) approach have been used since it can satisfy voltage, thermal and stability constraints among all other methods available. The main objectives include identification of best location for UPFC to get maximum ATC enhancement and to propose a novel method for optimizing the UPFC PV bus location using Generation Shift Factor (GSF) so that power system transmission network can deliver more number of power trades.