以時間延遲估測控制應用於IEA15MW浮動半潛式離岸直驅式風力發電機之功率控制及全機組動態分析之研究

Abstract

本研究針對15MW離岸浮動半潛式風力發電機全系統動態及系統控制的模擬。以IEA Wind TCP Task37 15MW參考風機為基礎來建置模型及UMaine Volturn US-S建置半潛式浮台，繫泊系統部分由三條繫纜所組成並以水深70m設計。全系統動態建模以多個軟體結合空氣動力、波浪力、結構系統動態、控制系統動態的分析。風力發電機組的機構以SIMPACK建置，包括風力發電機之葉片、塔架、輪轂、機艙以及水下基礎的浮台及繫泊系統，由AeroDyn計算葉片之空氣動力學分析，以WAMIT計算出浮台水動力係數，並由HydroDyn進行水動力分析，繫泊系統分析以MAP++進行計算，同時推導直驅式永磁同步發電機、轉速控制系統、液壓葉片變旋角系統及功率控制器之數學模型並建置於MATLAB/SIMULINK。以SIMPACK整合AeroDyn、HydroDyn以及MAP++，並透過SIMPACK內建的SIMAT介面與MATLAB/SIMULINK連結達成即時同步模擬，進行在不同的風況及海況條件下全系統閉迴路控制系統的動態模擬與控制分析。本研究在模擬條件上，先以3m/s到25m/s五階遞增風速模擬全區域風速的全系統動態分析，再以不同平均風速外加百分之三的紊流強度，模擬自然情況下風況的系統動態，並以風速對應之波高為水動力模擬環境參數，以接近真實環境。另外，本論文應用時間延遲控制方法在功率控制器，基於時間延遲估計，可估測並抵銷動力學的非線性項、未知系統參數及時變性的環境干擾，能得到有效的功率控制結果，並與PID控制器的控制結果比較，本文提出的控制理論能有效消除PID控制器所遇到的過衝過大問題。並發展創新壓載控制策略，在浮式載台的穩定性方面，減低浮台角度變化量以增進發電功率穩定度。最後本研究也將模擬結果與在相同條件下以FAST模擬的結果進行比對驗證，驗證本文所提以SIMPACK架構整合模擬結果之正確性。

The objective of this study is to investigate the dynamic co-simulation and control of a 15MW semi-submersible floating offshore wind turbine (FOWT), which is based on IEA 15MW Offshore Reference Wind Turbine and UMaine Volturn US-S semi-submersible floater in IEA Wind TCP Task37. The mooring system contains three mooring lines for water depth of 70 m. The overall system modeling and simulation was implemented by combining aerodynamics, hydrodynamics, mechanical dynamics, and control system dynamics. The mechanism system of the FOWT was established in SIMPACK, including blades, tower, hub, nacelle, floater and mooring system. The aerodynamic is analyzed by AeroDyn; the hydrodynamic analysis was conducted by HydroDyn with the hydrodynamic coefficients from WAMIT, and the mooring system was analyzed with MAP++. The mathematical model of direct-drive permanent magnet synchronous generator (PMSG), rotor speed control system, hydraulic blade pitch control system and power controller were achieved in MATLAB/SIMULINK. This study integrates AeroDyn, HydroDyn and MAP++ with SIMPACK, and connect with MATLAB/SIMULINK through SIMPACK's built-in SIMAT interface to achieve co-simulation and realize the dynamic simulation and control analysis of the FOWT under various wind and wave conditions. The overall dynamic co-simulation of FOWT system was firstly conducted under a fifth-order increasing trajectory wind speed from 3m/s to 25m/s to observe the response of FOWT. In addition, the dynamic analysis of FOWT under natural conditions is also simulated by using wind input with 3% turbulence intensity, and the corresponding significant wave height. This study proposed a power controller using Time–Delay Estimation (TDE) method to eliminate system nonlinearity and turbulence for achieving good performance of keeping the rated output power. The simulation results showed that the proposed TDE power controller can effectively eliminate the overshoot problem in comparison with that using PID power controller. Besides, a new ballast strategy was also proposed to improve power generation stability by stabilizing the dynamics of the platform. Finally, in order to verify the correctness of the proposed co-simulation, the simulation results were compared with that of FAST under the same wind and wave conditions.