Thyristor Excitation Research Articles

Direct phase modelling of synchronous generators

Accurate nonlinear modelling of the synchronous generator in the dqo reference frame has been well documented. To extend the analysis to a wider range of loading conditions, the generator is modelled in the paper in the abc reference frame. The unsaturated, static and dynamic saturated inductances of the machine in this reference frame are obtained using conventional dqo-abc transformation techniques. A new set of equations in the phase reference frame has been derived employing the dynamic inductance concept. The model utilises new dynamic saturated inductances that remove the error present in the conventional direct phase nonlinear model using only static saturated inductances. The mathematical model has been used to simulate the performance of a laminated salient-pole alternator with direct thy-ristor excitation. The predicted results show good agreement with test results.

Application of Power System Stabilizers for Enhancement of Overall System Stability

This paper provides a detailed account of analytical work carried out to determine the parameters of power system stabilizers (PSS) for the Darlington nuclear generating station presently under construction in eastern Ontario. The results presented are, however, of general interest and provide a comprehensive analysis of the effects of the different stabilizer parameters on the overall dynamic performance of the power system. They show how stabilizer settings may be selected so as to enhance the steady-state and transient stability of local plant modes as well as inter-area modes in large interconnected systems. In addition, it is shown that the selected parameters result in satisfactory performance during system islanding conditions, when large frequency excursions are experienced. Darlington GS, when completed by 1992, will comprise four 1100 MVA, 0.85 p.f., 1800 RPM turbine generators with "CANDU-PHW" reactors, moderated and cooled by heavy water. The station will be incorporated into the 500 kV network through three double-circuit lines. The units will be equipped with transformer-fed thyristor excitation systems and Delta-P-Omega type PSS [1, 2].

New dynamic inductance concept and its application to synchronous machine modelling

The transformer voltage terms in the generalised equations that describe the performance of the saturated electrical machine under dynamic conditions, involve some error. In this paper, a method is presented for the calculation of dynamic saturated inductances that, when used instead of the static ones, removes this error. The rotational voltage terms are still correctly calculated using the conventional static saturated inductances. To verify the validity of the dynamic inductance concept, a system consisting of a laminated salient-pole alternator with direct thyristor excitation has been studied. The predicted results for the sudden application and removal of balanced zero power factor loads shows good agreement with test results.

Evaluation of Field Insulation of Turbine-Generators with Higher Thyristor Excitation

Application of a thyristor excitation system with high ceiling voltage to the turbine-generator field has required precise evaluation on field insulation, especially against spiky voltage. This paper reports on the investigation of breakdown through and over the surface of field insulating components for thyristor voltage. Particular emphasis is placed on the method for estimating voltage endurance characteristics for thyristor voltage in hydrogen. We established a simple evaluating method on the rotor slot armor by using the relation of voltage endurance characteristics between ac and thyristor voltages. Estimation tests have proved that hazardous points are (a) the surface flashover of the creepage block for initial-stage characteristics and (b) degradation of the slot armor due to partial discharge for long-term characteristics.

Evaluation of Field Insulation of Turbine-Generators with Higher Thyristor Excitation

Evaluation of Field Insulation of Turbine-Generators with Higher Thyristor Excitation

Thyristor excitation of synchronous motors on exhausters in the sinter shop

Thyristor excitation of synchronous motors on exhausters in the sinter shop

Application of multivariable frequency response methods to control of turbogenerators

This paper deals with the design, evaluation and testing of an integrated control scheme for a turbogenerator equipped with a high-gain thyristor exciter and an electro-hydraulio governing system. Multivariable frequency response methods are used, and these are demonstrated to be eminently suitable for the design and analysis of turbogenerator controllers. It is shown that a control scheme consisting of an automatic voltage regulator with speed stabilizer, and speed governor with lead compensator, designed by the above methods, can greatly improve the dynamic and transient performance of a turbogenerator. This was confirmed by computer simulation, and by extensive tests on a laboratory model turbogenerator. The controllers in the oxcitor and governor loops are easily implemented, and the results show significant improvements in system damping, transient stability, and post-fault recovery of terminal voltage. It has thus been established that these controllers, designed on the basis of linearized mathemati...

Brushless Thyristor Excitation Systems.

This paper shows how brushless thyristor excitation systems for large synchronous generators are being evolved in the authors' organisation, outlines the electrical and mechanical advantages that accrue, and includes some results of a digital computer comparison of such systems with other forms of excitation.

Transient Behavior of Synchronous Machine with Shunt-Connected Thyristor Exciter Under System Faults

This paper covers an analytical method for transient behavior of a synchronous machine with shunt-connected thyristor exciter under power system faults such as line-to-line and three-phase short-circuit faults, considering performances of the thyristor converter and characteristics of the excitation control system.