Edwin Lerch

Optimization and Coordination of Damping Controls for Improving System Dynamic Performance

This paper presents a global tuning procedure for FACTS device stabilizers (FDS) and power system stabilizers (PSS) in a multimachine power system using a parameter-constrained nonlinear optimization algorithm implemented in a simulation program. This algorithm deals with such an optimization problem by solving a sequential quadratic programming using the dual algorithm. The main objective of this procedure is to simultaneously optimize preselected parameters of the FDSs and PSSs having fixed parameters in coping with the complex nonlinear nature of the power system. By minimizing a nonexplicit target function in which the oscillatory rotor modes of the generators involved and swing characteristics between areas are included, interactions among the FACTS controls under transient conditions in the multimachine system are improved. A multimachine power system equipped with a TCSC and an SVC, as well as three PSSs, is applied to demonstrate the efficiency and robustness of the tuning procedure presented. The results obtained from simulations validate the improvement in damping of overall power oscillations in the system in an optimal and globally coordinated manner. The simulations also show that the stabilizers tuned are robust in providing adequate damping for a range of conditions in the system.

Advanced SVC control for damping power system oscillations

A new SVC (static VAR compensation) control for damping of power system oscillations has been developed. To increase system damping an SVC uses a phase angle signal estimated from the measurement of voltage and power at the SVC location. By means of an optimization and identification procedure, optimized design of the damping control with various control concepts can be determined, taking into account nonlinear power systems. As a result of this method it is possible to increase power system damping considerably, in particular in critical situations close to the stability limit, using only locally measured state variables at the SVC, thus leading to an increase in the transmission capability of the power system. >

A large integrated power system software package-NETOMAC

The simulation system NETOMAC/sup (R)/ (Network Torsion Machine Control) offers a wide range of modern methods of analyzing and synthesizing electric power systems. In order to design individual elements of transmission systems or to perform stability calculations on large systems, it is possible to simulate electrical networks in the time domain and also, with the aid of eigenvalue calculations, to study the frequency domain too. These methods find general application in the design of control systems add in analyzing the behavior of large networks. User support is provided in the form of a graphical interface to facilitate the inputting of the electrical systems and control structures, One uniform database is being used for all calculations regardless of whether time domain or frequency domain is being investigated. Workstations, PCs or notebooks provide the platform from which NETOMAC can provide the user with the flexibility, mobility and speed that he needs.

Faster than real time: Dynamic security assessment for foresighted control actions

In this paper, implementation of power system dynamic security assessment (DSA) into real time simulation environment is described. For this purpose, a powerful simulation system has been used and a flexible security assessment framework developed. The DSA system constructed is user oriented and enables simple evaluation of power system security. The assessment is made in respect to some user defined security constraints considering normal or contingency provoked system operation. For reporting of the results different visualization formats are available. The DSA system is fully automatic and can process any number of study cases without user interaction. It targets high flexibility in power system research and maximum performance at minimum hardware requirements.

Optimization and coordination of damping controls for improving system dynamic performance

Summary form only given as follows. This paper presents a global tuning procedure for FACTS device stabilizers (FDS) and power system stabilizers (PSS) in a multimachine power system using a parameter-constrained nonlinear optimization algorithm implemented in a simulation program. This algorithm deals with such an optimization problem by solving a sequential quadratic programming using the dual algorithm. The main objective of this procedure is to simultaneously optimize preselected parameters of the FDSs and PSSs having fixed parameters in coping with the complex nonlinear nature of the power system. By minimizing a nonexplicit target function in which the oscillatory rotor modes of the generators involved and swing characteristics between areas are included, interactions among the FACTS controls under transient conditions in the multi-machine system are improved. A multi-machine power system equipped with a TCSC and an SVC as well as three PSSs is applied to demonstrate the efficiency and robustness of the tuning procedure presented. The results obtained from simulations validate the improvement in damping of overall power oscillations in the system in an optimal and globally coordinated manner. The simulations also show that the stabilizers tuned are robust in providing adequate damping for a range of conditions in the system.

Monitoring and Reporting of Security of Power System Low-frequency Oscillations

Abstract This article deals with the monitoring and visualization of security of power system oscillation modes. The monitoring is performed by means of a performance index based on the traditional stability measure, but it reports on relative changes in the system low-frequency characteristics in a more indicative manner. In addition to introducing a dramatic progression at marginal changes in the modes characteristics, the index also communicates the “relative distance” to the dangerous system stages by reporting the available security margin. Using the index, system states can be meaningfully visualized. In this article, the matrix visualization technique is applied for that purpose. The technique sufficiently facilitates human interaction for identification of the system states under different network and operating conditions.

Vision 2020: Blackout prevention by combined protection and network security assessment

The paper presents the application of software tools to simulate system dynamic behaviour together with the possibility to select critical contingencies of an electrical energy system. The protection system with relay functions, characteristics, settings and communication schemes will be considered. Possible visualization methods are presented which can support the operators to select critical system states - either of the primary or the protection system. Insecure operating conditions can be monitored in the time domain using the full system representation in real time or by calculating the eigenvalues of the system to monitor weakly damped system states and stability margins. Warnings about unselective protected areas can popup for fast information or they can be shown with the corresponding relays in single-line diagrams as a basis for a new protection coordination study. The locations of short circuits with corresponding trip times and unselective trips or no trips can be monitored in two- or three-dimensional diagrams. The optimized settings can be directly transmitted to relays, which are able to receive the adaptive settings.

Small signal security index for contingency classification in dynamic security assessment

This paper presents a security index for quantifying the small signal security of power systems. The index refers to the characteristics of system oscillation modes and delivers the degree of change in system security due to contingencies. The index can be of supplemental use in power system contingency screening and ranking. Moreover, the paper suggests the concept of aggregating the index with the established index for dynamic security inference. The aggregation concept allows individual application of each of the indexes in partial security investigations or application of both in the complete security investigations.

Vision 2020 dynamic security assessment in real time environment

In this paper, implementation of power system dynamic security assessment (DSA) into real time simulation environment is described. For this purpose, a powerful simulation system has been used and a flexible security assessment framework developed. The DSA system constructed is user oriented and enables simple evaluation of power system security. The assessment is made in respect to some user defined security constraints considering normal or contingency provoked system operation. For reporting of the results different visualization formats are available. The DSA system is fully automatic and can process any number of study cases without user interaction. It targets high flexibility in power system research and maximum performance at minimum hardware requirements.

DSA-Visualisation Monitoring and Ranking of System Dynamic Behaviour

The paper presents the application of a software tool to simulate system dynamic behavior together with the possibility to select critical contingencies of an electrical energy system. These cases are visualized and a ranking decision is introduced to support the operators to select critical system states. Insecure operating conditions can be monitored in the time domain using the full system representation in real time or by calculating the eigenvalues of the system to monitored weakly damped system states and stability margins.