Implementatıon Of A Hıgh Dynamıc Response Statıc Excıtatıon System For Synchronous Generators


Thesis Type: Doctorate

Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2017

Student: MUSTAFA BAHA BAYRAM

Supervisor: İBRAHİM SEFA

Abstract:

Synchronous generators are commonly used in energy generation together with the systems such as hydraulic and thermal power plants and wind turbines. If the generator power levels are larger than a few MW, external excited topologies are commonly used, because of the faster response of them and the difficulties in designing self-exciting topologies at higher rated power. The power values of external excited generators can reach hundreds of MW, and the excitation power can reach up to a few MW values. The excitation current required for excitation circuits of high power generators is provided by 6 or 12 pulse phase controlled thyristor rectifiers. However, the delay in the response of the controlled rectifiers and the improvements in the power electronics have led to the creation of new options. In this study, an automatic voltage regulator system with an interleaved buck converter topology, which has high frequency and which can be increased in power with its modularly, has been proposed as an alternative to thyristor controlled static excitation systems. The proposed system removes the slow response disadvantage of thyristor-controlled systems for dynamic load and system conditions. At the same time, it eliminates the extra shaft tension due to low frequency, hig.h amplitude harmonic components at the output voltages of thyristor-controlled systems and extends the life of the generator. In the development process, the electromagnetic modeling of the synchronous generator is performed in the software environment by means of finite element analysis. Co-simulations of the power-electronic circuit of the modeled generator and the proposed interleaved buck converter have been performed. The simulation results are verified by an experimentally established excitation system. The results obtained from the simulation results and the experimental results show that the system provides better performance in terms of the system step response and in terms of the inductor current ripple level with the help of channel number. With in the proposed system, all the measurement, monitoring, recording, high frequency phase shift pulse width modulation generation and all control processes hase been deployed in NI CompactDAQ platform with an embedded control system. The virtual instrument that runs on this platform and manages the process is designed in the LabVIEW software environment.