June 11, 2010NATIONAL POWER ELECTRONICS CONFERENCE1 A HARDWARE GRID SIMULATOR TO TEST GRID-CONNECTED INVERTER SYSTEMS ARUN KARUPPASWAMY B DR.VINOD JOHN Power Electronics Group Department of Electrical Engineering Indian Institute of Science, Bangalore
June 11, 2010NATIONAL POWER ELECTRONICS CONFERENCE2 GRID SIMULATOR – AN INTRODUCTION What? Grid simulator is a high power inverter controlled to simulate the effects (voltage sag, voltage swell, frequency variation and the like) generally observed in a grid. Why? To test grid connected systems developed in the lab – under actual grid conditions Variable voltage sources do not help as they do not include the line impedance
June 11, 2010NATIONAL POWER ELECTRONICS CONFERENCE3 A LITTLE MORE DETAIL A Typical Grid Disturbance
June 11, 2010NATIONAL POWER ELECTRONICS CONFERENCE4 GRID SIMULATOR HARDWARE SETUP FEC INVERTER L L L L C C DC Bus To Load From Grid Grid Impedance The system is controlled to imitate the grid along with its line impedance. Various grid disturbances can be emulated to test systems that are connected to the grid.
June 11, 2010NATIONAL POWER ELECTRONICS CONFERENCE5 EMULATION OF IMPEDANCES Reference Voltage for Inverter: Resistance Drop: Inductance Drop:
June 11, 2010NATIONAL POWER ELECTRONICS CONFERENCE6 EMULATION OF INDUCTANCE Low Pass Filter Approach: State Estimation Approach: Controller + -
June 11, 2010NATIONAL POWER ELECTRONICS CONFERENCE7 IMPLEMENTATION METHODOLOGY
June 11, 2010NATIONAL POWER ELECTRONICS CONFERENCE8 DSP RESULT – A THREE PHASE VOLTAGE SAG
June 11, 2010NATIONAL POWER ELECTRONICS CONFERENCE9 DSP RESULT – POINT OF WAVE EVENT
June 11, 2010NATIONAL POWER ELECTRONICS CONFERENCE10 DSP RESULT – EMULATION OF INDUCTANCE
June 11, 2010NATIONAL POWER ELECTRONICS CONFERENCE11 DSP RESULT – BANDWIDTH OF EMULATION
June 11, 2010NATIONAL POWER ELECTRONICS CONFERENCE12 CONCLUSION 1.The grid simulator is a useful and essential hardware that is required for projects on grid-connected systems. 2.The grid simulator can be useful to study the impact of events such as sags and swells, frequency variations and system faults on grid interactive converters such as STATCOM. 3.Issues in the development of the grid simulator would be the emulation of inductance and the hardware issues that might arise when testing the equipment under test like over currents leading to tripping of the Grid Simulator. 4.In this paper, impedance emulation has been discussed. Resistive and inductive impedances that characterizes the power system has been emulated in the DSP. 5.The same is in the process of being implemented using the 50kVA inverter that is being constructed. 6.The study on the DSP controller indicates that it is feasible to implement such a system.
June 11, 2010NATIONAL POWER ELECTRONICS CONFERENCE13 REFERENCES 1.IEEE Standard , “IEEE Standard Conformance Test Procedures for Equipment Interconnecting Distributed Resources with Electric Power Systems”, IEEE, Richard Zhang, Mark Cardinal, Paul Szczesny and Mark Dame, “A Grid Simulator with Control of Single-Phase Power Converters in D-Q Rotating Frame”, IEEE, 2002, pp National Renewable Energy Laboratory, Distributed Energy Resources Test Facility, 4.Gene F. Franklin, Michael L. Workman and David Powell, “Digital Control of Dynamic Systems”, 3 rd Ed., Addison-Wesley Longman Publishing Co., Inc.
June 11, 2010NATIONAL POWER ELECTRONICS CONFERENCE14 DISCUSSION