Gas Turbine-Generator System Duality Study for Real-Time Phil Emulation Using Power Electronics Converters
Gas turbine-synchronous generator (GT-SG) systems are the main source of power and propulsion onboard most naval ships. Since this system plays a vital role in accomplishing the ship's mission, a lot of testing is conducted to ensure that the system is ideal for the ship in which it is to be installed. Testing of such systems is very expensive and complicated. These systems are very large in size and require a very large testing facility for storage. Also, it is a very complicated and high maintenance system. Therefore, it requires a lot of personnel for maintenance which further increases the total cost. Finding ways to reduce the cost and total amount of waste for testing these systems is essential for the day-to-day operation of the United States Navy. They have invested and continue to invest large sums of money in research which concentrates on finding reliable testing models which can potentially reduce the current cost and waste of testing such systems. The Energy Conversion and Integration trust (ECI) at the Center for Advanced Power Systems of Florida State University has developed a NLDL test bed. This test bed, shown in Appendix A, is comprised of real hardware developed converters for testing the Navy's All-Electric-Ship (AES) proposed power system. It is used to perform various tests on control and stability under the expected non-linear loads setting of the Navy's weapons systems. It can also be used to explore other research topics related to distributed power systems and other related hardware tests. The incorporation of this test bed is part of the next phase of this work which includes PHIL testing of the system. PHIL involves the use of incorporating physical power hardware to a simulation while CHIL refers to physically involving a controller with a simulated environment. Both forms of HIL allow for more in-depth validation techniques by actually involving the real hardware in simulation . In this CHIL methodology, the simulated environment involves a real-time component model of the NLDL test bed where all parameters and components have been modeled to be an exact replica of the actual test bed in a RTDSTM system. The controller part of the CHIL involves the actual model of the GT-SG system which is computed in real time utilizing a RPC. In this particular work, the RPC is a dSPACETM unit. The CHIL methodology lays out the ground work and provides a link for the future implementation of PHIL. The CHIL method allows for testing of all communication links between the hardware. Therefore, once all the systems are tested and are operational, the hardware simulated environment can be replaced with the actual hardware of the NLDL test bed. As stated, this NLDL test bed is comprised of several power electronics converters such as Active-Front-End (AFE), Inverter (INV), and Neutral-Point-Clamp (NCP). The CHIL simulated hardware environment provides an exact replica of this test bed and is a great testing model for such a system. The purpose of this thesis is to utilize the AFE and INV to emulate the GT-SG system, and to provide a translation/duality between the GT-SG system variables (torque, speed, voltage, and current) and the AFE-INV system variables (voltages and currents) through the emulation methodologies. In this work, two methods which can be utilized to emulate any GT-SG system operation in a wide range of steady state, dynamic, and transient performance through the use of these power electronics converters, regardless of power level without loss of generality, are presented. The dynamic equations of the GT and SG are utilized to construct their models, and are implemented in MATLAB/Simulink®. The AFE is utilized to conduct the GT emulation and the INV is utilized to conduct the SG emulation. Controls are set up for the GT-SG model and the control signals are used to provide the switching commands for the AFE and INV, respectively, to perform the emulation. Parameter translation/duality between the GT-SG model and the AFE-INV model are also provided. For the purpose of this work, the GT-SG system studies and emulation are conducted in the distributed generation power levels. This work can/will be expanded to include the ship's main distribution power levels as part of the future work.
Converters, Duality Study, Emulation, Gas Turbine, Generator, Hardware-in-the-loop
April 1, 2012.
A Thesis submitted to the Department of Electrical and Computer Engineering in partial fulfillment of the requirements for the degree of Master of Science.
Includes bibliographical references.
Chris S. Edrington, Professor Directing Thesis; Hui Li, Committee Member; Rodney Roberts, Committee Member.
Florida State University
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