ÇUKUROVA UNIVERSITY INSTITUTE OF NATURAL AND APPLIED ...

4.3.1.2. Synchronous Reference Frame (SRF) .................................... 64
4.3.1.3. SOGI-PLL .............................................................................. 67
4.3.1.4. Reference Generation Using Sag Detection Methods ............ 69
4.3.2. Voltage Injection Strategy.................................................................... 71
4.3.3. Voltage Control Strategy: Closed Loop ............................................... 76
4.3.4. Gate Signal Generation ........................................................................ 78
4.3.4.1. Inverter .................................................................................... 79
4.3.4.2. DC-DC Converter ................................................................... 80
5. SIMULATION RESULTS AND CASE STUDIES .............................................. 83
5.1. Comparison of Sag Detection Methods (EPLL, SRF and SogiPLL) .............. 85
5.2. Simulation Results for Open Loop and Closed Loop ...................................... 88
5.2.1. Open Loop Voltage Control Method ................................................... 88
5.2.1.1. Case 1: Single Phase Voltage Sag .......................................... 89
5.2.1.2. Case 2: Two Phase Voltage Sag ............................................. 91
5.2.1.3. Case 3: Three Phase Voltage Sag ........................................... 94
5.2.2. Closed Loop Voltage Control Method ................................................. 97
5.2.2.1. Case 4: Single Phase Voltage Sag .......................................... 98
5.2.2.2. Case 5: Two Phase Voltage Sag ........................................... 100
5.2.2.3. Case 6: Three Phase Voltage Sag ......................................... 103
5.2.3. Comparison of Voltage Control Methods .......................................... 106
6. CONCLUSION .................................................................................................... 109
REFERENCES ......................................................................................................... 112
BIOGRAPHY .......................................................................................................... 121
APPENDIX .............................................................................................................. 122
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