DC링크 전압을 이용한 PMSG MV 해상 풍력 발전기의 유효전력 지령모드 절환 = Command Mode Transition of Active Power using DC-link Voltage for PMSG MV Offshore Wind Turbine

다국어 초록 (Multilingual Abstract)

This thesis proposes a command mode transition of active power using dc-link voltage for Permanent Magnet Synchronous Generator (PMSG) Medium Voltage (MV) offshore Wind Turbines (WT). Benchmarking against the conventional control method is performed based on a neutral point clamped three-level back-to-back type voltage source converter. The ramping rate criterion of complex power is proposed to select the proper switching vector in DPC for a three-level NPC converter. This criterion is to maximize the ramping rate of complex power under the limitation of available switching vectors in a corresponding sector. Using a grid command and MPPT mode, the proposed control method automatically controls the generated output power to satisfy a grid requirement from the hierarchical wind farm controller. Also the proposed control method is compared with the conventional control method in loss and thermal distribution analysis. The command mode transition of active power using dc-link voltage method is confirmed through PLECS simulations based on Matlab. Simulation result shows that proposed control method achieves a much shorter transient time and lower peak junction temperature of generated output power than the conventional control method under a step response and steady-state condition. The proposed control method of VOC and DPC makes it possible to provide a good dynamic performance for PMSG MV offshore WTs in order to generate a high quality output power.

목차 (Table of Contents)

• 1. Introduction 1
• 2. Direct Power Control for Three-level NPC Converter 5
• 2.1 Modeling for direct power control 5
• 2.2 Ramping rate criterion of complex power for the selection of switching vectors 10
• 3.Conventional and Proposed Control Scheme for Entire System 15
• 3.1 Conventional control scheme 15
• 3.2 Proposed control scheme 18
• 4. Simulation Verification 22
• 4.1 Case 1: steady-state condition of power generation of 5MW (MPPT mode) 25
• 4.2 Case 2: control mode change (MPPT mode → grid command mode) 27
• 4.3 Case 3: control mode change (MPPT mode → grid command mode → MPPT mode) 31
• 4.4 Comparison of power loss distribution 34
• 5. Conclusion 37
• References 38
• 요약(국문초록) 42