Real-time Operation Of Power System Research Articles

Reserve constrained dynamic optimal power flow subject to valve-point effects, prohibited zones and multi-fuel constraints

This paper proposes a new method called the enhanced charged system search algorithm in order to solve the reserve constrained dynamic optimal power flow. The optimal power flow (OPF) is applied to develop the corrective strategies and to make the least cost dispatches. The static OPF solutions will usually result in unattractive generation cost in a dynamic environment, so to cope with this problem it is necessary to solve the dynamic optimal power flow which considers time-related constraints along with time-separated limits. Also, some restrictions such as prohibited operating zones and valve-point effects beside the multi-fuel type of generation units should be taken into account in order to get closer to the real condition of the power systems. Furthermore, to ensure secure real-time power system operations, the system operator must schedule sufficient resources to meet energy demand and operating reserve requirements, simultaneously. This problem is a complex optimization problem spontaneously which its complexity is increased with considering all above constraints. This paper utilizes an enhanced charged system search algorithm, which is a newly developed optimization algorithm, to solve the proposed problem. This algorithm is equipped with a novel mutation strategy in order to increase the population diversity and to amend the convergence criteria. For validating the ability of the proposed algorithm, it is applied to two small- and large-scale case studies including 30 and 118 buses test systems.

Gaming-Based Reserve Constraint Penalty Factor Analysis

To ensure secure real-time power system operations, the system operator must schedule sufficient resources to meet energy demand and operating reserve requirements simultaneously. Under a joint real-time energy-reserve market regime, a dominant market participant can exercise pricing power by withholding reserve capability or by marking up energy offers. This paper examines the short-term impact of the choice of reserve price cap on participant behavior and market outcomes. A Stackelberg game is utilized to analyze the strategic bidding behaviors of the dominant participants assuming a range of reserve price caps and market conditions. The market participants play the role of the leaders, while the independent system operator is treated as a follower. The proposed model is applied to the New England electricity market. The computed solutions show that although the reserve price cap is unable to eliminate physical withholding behaviors, it disciplines the participants and limits incentives to withhold economically. Also, it limits prices to a reasonable level during reserve shortage events when only supply-side market power mitigation options are available. Absent any transmission improvements or effective demand response participation, the reserve price cap remains an effective tool to mitigate the impact of the exercise of supplier market power.

Application of Bayesian Learning Mechanism in Power System Transient Stability Assessment

One of the most challenging problems in real-time operation of power system is the prediction of transient stability. Fast and accurate techniques are imperative to achieve on-line transient stability assessment (TSA). This problem has been approached by various machine learning algorithms, however they find a class decision estimate rather than a probabilistic confidence of the class distribution. To counter the shortcoming of common machine learning methods, a novel machine learning technique, i.e. ‘relevance vector machine’ (RVM), for TSA is presented in this paper. RVM is based on a probabilistic Bayesian learning framework, and as a feature it can yield a decision function that depends on only a very fewer number of so-called relevance vectors. The proposed method is tested on New England power system, and compared with a state-of-the-art ‘support vector machine’ (SVM) classifier. The classification performance is evaluated using false discriminate rate (FDR). It is demonstrated that the RVM classifier can yield a decision function that is much sparser than the SVM classifier while providing higher classification accuracy. Consequently, the RVM classifier greatly reduces the computational complexity, making it more suitable for real-time implementation.

Development of the loss minimization function for real time power system operations: a new tool

This paper presents development of an innovative tool for online power system operation. It is designed to operate in an energy control center (ECC) environment. Online application consists of using the developed optimal power flow (OPF) based loss minimization (LM) function for real time power system corrective actions by ECC dispatchers. The results of online power system operations using the LM function are reported to demonstrate economic and security gains for power system operations.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Power system network topology error detection

The accuracy of state estimation determines the usefulness of real-time power system operation and control applications. To have an accurate state estimation it is essential to have the capability of detecting bad measurement data and topology errors in the model. While analogue measurement errors have received considerable attention, relatively little effort has been given to detection of topology errors. A procedure that combines numerical computation and various consistency checks is proposed to detect topology errors in the state estimation model. Tests based on real-time measurement data collected in an energy control centre have indicated that the proposed method can be used to detect branch inclusion, exclusion and bus configuration errors.

System voltage and reactive power control: A computer-assisted manual/automatic concept

The paper describes a new computerassisted software concept for hierarchic control of voltages and reactive powers in the real-time operation of power systems. The concept uses the local and centralised control levels. The local level employs existing automatic or manually operated control devices on regulating resources. The centralised level applies a superimposed computerassisted manual control, based on reactive optimal power flow, with a dedicated criterion function dealing with system economy and security. An adaptive system zoning is incorporated in the concept, aimed at the matching, inherently local, character of voltage/reactive power control.

Computer Aided Instruction of Power System Security Control Functions

This paper describes instructional software and their utilization for the instruction of courses in the area of real-time control and operation of power systems. The objective of these courses is to study the real-time control functions as performed by modern energy control centers. The main topics addressed are: (1) data acquisition and estimation, (2) energy management/automatic generation control, and (3) security monitoring and control. Effective instruction of these topics is performed with the use of a number of interactive computer programs. These programs assist students in studying and understanding the concepts underlying the real-time operation of power systems. An overview of the courses and computer programs utilization procedures is provided. The focus of the paper is on security control concepts and description of the computer aided approach to enhance student comprehension. Typical homework assignments are described to illustrate the procedures. Student response to this approach is excellent.

Development of Courses on Power System Energy Control Centers

This paper presents two graduate courses in the area of real-time control and operation of power systems. The objective of the courses is to study real-time control functions as performed by modern energy control centers. The main topics addressed are: 1) data acquisition and estimation, 2) energy management/automatic generation control, and 3) security monitoring and control. A unique feature of the courses is the use of a number of interactive computer programs. These programs assist students in studying in depth and understanding the concepts underlying the real-time operation of power systems. The paper describes course contents and the utilization of computer programs to enhance student comprehension of the concepts involved. Typical homework assignments are described to illustrate the utilization of the computer programs. The courses are presently offered at Georgia Tech, with excellent student response.

Interactive security evaluation in power-system operation

The real-time operation of power systems requires security assessment and enhancement computations to ensure that the system stays in the normal state for as long as possible. The paper describes an interactive computer package with colour graphics for power-system operational studies. The package includes load flows, fault analysis and security enhancement. A decoupled algorithm is used for security enhancement, and offers the operator a choice of feasible corrective actions to alleviate line overloads. These corrective actions include generator rescheduling, network voltage adjustments, switching of reactive compensation and the control of phase shifters. Experiments on three test systems are summarised and discussed