On-line Transient Stability Analysis Research Articles

Graphical Processing Unit Based Time-Parallel Numerical Method for Ordinary Differential Equations

On-line transient stability analysis of a power grid is crucial in determining whether the power grid will traverse to a steady state stable operating point after a disturbance. The transient stability analysis involves computing the solutions of the algebraic equations modeling the grid network and the ordinary differential equations modeling the dynamics of the electrical components like synchronous generators, exciters, governors, etc., of the grid in near real-time. In this research, we investigate the use of time-parallel approach in particular the Parareal algorithm implementation on Graphical Processing Unit using Compute Unified Device Architecture to compute solutions of ordinary differential equations. The numerical solution accuracy and computation time of the Parareal algorithm executing on the GPU are demonstrated on the single machine infinite bus test system. Two types of dynamic model of the single synchronous generator namely the classical and detailed models are studied. The numerical solutions of the ordinary differential equations computed by the Parareal algorithm are compared to that computed using the modified Euler’s method demonstrating the accuracy of the Parareal algorithm executing on GPU. Simulations are performed with varying numerical integration time steps, and the suitability of Parareal algorithm in computing near real-time solutions of ordinary different equations is presented. A speedup of 25× and 31× is achieved with the Parareal algorithm for classical and detailed dynamic models of the synchronous generator respectively compared to the sequential modified Euler’s method. The weak scaling efficiency of the Parareal algorithm when required to solve a large number of ordinary differential equations at each time step due to the increase in sequential computations and associated memory transfer latency between the CPU and GPU is discussed.

Damping Representation for the Fifth-Order Generator Model in Transient Behaviors

An expression of the compensation torque is derived to reduce the difference between the fifth-order generator model and the seventh-order model. It is appended to the swing equation in the fifth-order model, with the voltage equations and the flux linkage equations unchanged. Based on the singular perturbation theory, the stator transients are approximated. The fast current components of three rotor windings are represented by equivalent d - and q -axis stator current increments that create the same stator flux linkage. The relationship between this torque and damping is clarified from a physical viewpoint. Simulations on two systems show that the compensation torque reduces the model difference. The proposed damping preserving model overcomes the difficulty in determining the damping torque coefficient and is applicable to online transient stability analysis.

Power system energy analysis incorporating comprehensive load characteristics

The energy function method developed so far assumes that the active load is constant. However, most of the actual load is voltage dependent, which hinders the application of the energy analysis method to the actual power system. On the other hand, the fast development of measurement techniques, especially the wide area measurement systems (WAMS) applied widely in worldwide power system nowadays, presses for the on-line transient stability analysis tools based on the system measurements. The voltage-dependent load into the energy analysis of power system transient stability is discussed. The effect of the comprehensive load characteristics on the system energy is discussed and a WAMS-based energy indicator on the system stability status is proposed. The indicator is easy to be calculated and thus real-time in the operation centre is monitored. The proposed method does not rely on any specific load model, and various load characteristics on different buses can be considered. Simulations on two test systems verify the effectiveness of the proposed method.

Development of a general intertrip monitoring system for the NGC network

For some time now, National Grid Company (NGC) has been developing on-line transient stability analysis tools. A particular need is the development of a facility that will help in the monitoring of intertrip schemes. This paper, therefore, describes the features of the General Intertrip Monitoring System (GIMS) facility developed for the NGC system and currently running on-line at the National Control Centre. The paper also demonstrates the operational experience in using this tool.

98/03027 Stability issues and new techniques for on-line transient stability analysis in Asia

98/03027 Stability issues and new techniques for on-line transient stability analysis in Asia

Stability issues and new techniques for on-line transient stability analysis in Asia

With the fast expansion of capacity in electric power systems in recent years, there is a pressing need to include on-line transient security analysis (TSA) capability in the energy management systems in Asian power utilities. Based upon the transient stability issues of today's power systems, the challenge to the implementation of new on-line transient stability assessment tools is first presented. Reviews on TSA methods under development are presented to show their potential for on-line applications. New techniques developed recently and future research issues for this area are introduced.

A Hybrid Method for Transient Stability Analysis

Abstract Direct method and Time-domain method are two main methods of power system transient stability analysis. They have complementary superiorities and drawbacks . This paper presents a hybrid method for transient stability analysis, which combines the desirable features of the two methods. Based on correct identifying Critical Clusters (CC), it can find Critical Clearing Time(CCT) and give stability index quickly and precisely. Furthennore, detail models of power system can be considered in it . This method is successfully tested on the reduced system of 28 generators and 143 buses. It is shown to be a potential tool for on-line transient stability analysis.

BC Hydro's on-line transient stability assessment (TSA) model development, analysis and post-processing

This paper presents the theoretical background and analytical methods developed for BC Hydro's on-line transient stability assessment (TSA) module. It concentrates on the preprocessing modeling, stability analysis/margin calculation and post processing techniques, the architecture, hardware and implementation are presented in a companion paper. BC Hydro's TSA has been tested with thousands of cases using a large scale detailed basecase derived for on-line analysis, sample tests are presented in this paper.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An on-line dynamic security analysis system implementation

Power system online dynamic security analysis has recently become realistic due to advances in analytical techniques and computer technology. This paper presents experience from implementation of the online transient stability analysis system at the B.C. Hydro control center. Implementation of the online system was conceived as part of a broader online dynamic security analysis system. As a description of what is believed to be the first implementation of a full-scale online transient stability analysis, this paper provides an insight into the design and evolution of online dynamic security analysis.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Extended equal area criterion justifications, generalizations, applications

The extended equal area criterion (EEAC) for online transient stability analysis is considered with the following objectives. The first is to state systematically its main hypotheses and key conditions, justify the former, and suggest means to guarantee the latter. The identification and error analysis of critical machines are among the investigated issues. The second is to scan all possible types of instabilities likely to arise in practice and devise means to treat them. The extension of the EEAC to cases beyond the so-called first-swing stability makes it more robust than all direct methods developed up to now. The third objective is to extract essential information out of a large body of simulations and show that the above improvements and extensions enhance the EEAC accuracy and its capability to work properly even under stringent conditions. Possible EEAC applications are also discussed, and uses of the method as such or as an auxiliary technique for more sophisticated approaches are suggested. >