This dissertation investigates the analysis of an excitation system and a starting equipment for gas-turbine synchronous machines and presents the design method for them. It is explained how to control the starting equipment for the gas-turbine with a load commutated inverter and the excitation system with a full wave phase controlled rectifier. Control module and special module of the starting equipment for the gas-turbine were designed to be compatible with each other. Mathematical analysis for the synchronous machines was performed since the starting equipment and the excitation system aim at controlling it. This analysis was used to simulate the synchronous machine using SIMULINK and it was found that response characteristics of the model are similar to the actual ones. Control methods and driving principles of the starting equipment are divided into forced and natural commutation with respect to the operation modes.
Also, a latest sensorless estimation scheme using an integrator with adaptive compensation algorithm are described in detail for initial rotor position and speed estimation of the synchronous machine. Six control and four limit functions for this excitation control system were analyzed as well. In addition, field-weakening control mode was validated which is operated during starting conditions. SIMULINK was used to simulate the control scheme for the proposed excitation system and the starting equipment. Modeling of the synchronous machine, load commutated inverter and excitation system is performed and the characteristics of the forced and natural commutation mode was reflected for the load commutated inverter. The sensorless scheme was applied after confirming the result of the simulation with sensor. The comparison shows that the sensorless algorithms estimate the rotor position and the speed properly. The modeling of the terminal voltage and the current control of the synchronous machine was used for the excitation system simulation and functional verification was conducted in order to verify the field-weakening control by performing coupled simulation. Prototype equipments were manufactured to validate the control logic of the excitation system and the starting equipment for the gas turbine using two panels equipped with identical control modules to integrate control systems. VxWorks was adopted as RTOS of the controller and application programs were coded using ISaGRAF which supports IEC 61131 standard. In order to eliminate problems with the speed, function block program and C language were used when the required speed is below and above 1kHz, respectively.
It was verified to satisfy the performance of the control function such as rotor speed and voltage build up using the synchronous machine with 5kVA capacity. The experiments for the starting equipment control scheme with algorithms for sensor and sensorless conditions were performed and the results are compared and reviewed. It is shown that the performance of the proposed control logic is satisfactory and the excitation system is stable under no-load and load condition (grid-connected). This study shows the integrated performance test of the excitation system and the starting equipment for the gas-turbine at the synchronous machine with 5kVA capacity. It is expected that this technology of the excitation system and the starting equipment would be applied to large power plants since all test results showed that the performance is satisfactory.