隨著再生能源的發展，風力發電的裝機容量佔系統中的供電比例越來越高，在歐美一些國家其風力發電所佔比例已超過10%，因此當系統發生故障，若風電機組任意地與系統進行解聯，會造成系統失穩；因此為了維持電力系統穩定運行，歐美國家都相繼提出風力發電的運轉規範，要求風電機組在系統故障期間必須維持併網運行，這種故障期間不間斷運行的能力稱為故障不間斷運轉能力。
然而當系統故障期間，風電機組維持併網運行，雙饋式感應發電機轉子側會產生極大的故障電流，因此衝擊電力轉換器，造成功率電晶體或者直流電容損壞，而導致電力轉換器失去控制能力，因此風電機組無法維持正常運行。本論文針對雙饋式感應發電機故障不間斷運轉控制策略進行深入研究。其貢獻有以下三點：
1.建構完整的雙饋式感應發電機動態模型，透過特徵値分析，探討當系統發生故障時，若未有合適的故障不間斷運轉控制策略，會造成雙饋式感應發電系統不穩定。
2.探討各種雙饋式感應發電機故障不間斷運轉控制策略：包含(1)保護電路控制策略，(2)應用回饋線性化的非線性控制理論於雙饋式感應發電機故障不間斷運轉控制策略，強化故障不間斷運轉能力，(3)實現滑動模式控制理論於雙饋式感應發電機故障不間斷運轉控制策略，強化故障不間斷運轉能力。
3.以電磁暫態分析軟體(PSCAD)建模，以單機對無限大匯流排以及兩區四機做為測試系統，驗證各種控制策略是否達到故障不間斷運轉，並比較其控制效能優劣。

As the number of wind installations has grown worldwide at unprecedented rates in recent years, the average size of installations has increased due to the advent of larger capacity machine, variable speed technology, and an increasing number of off-shore sites. The raises the concern that widespread tripping of wind generators following disturbances could lead to propagation of transient instabilities and could potentially cause local or system wide blackouts. This has provoked many utilities to adopt fault ride-through (FRT) capability for wind turbines.
This thesis will focus on the fault ride-through capability enhancement of conventional doubly-fed induction generators (DFIG), which are widely used in wind power generation. Basic operation principles and control algorithms of DFIGs and the corresponding converter for stability studies will be presented first. Simulation verifications are performed by PSCAD. In this thesis, technical enhancements of the FRT capability are achieved through the following steps:
1.Dynamical mechanisms of the linearized DFIG will be conducted by eigenvalue analysis. It will be shown that the DFIG system under the conventional current control method will become unstable if the grid voltage is sufficiently low.
2.The FRT capability can be enhanced by advanced control algorithms in addition to the conventional current control methods. The most straight forward method is the so-called crowbar protection. The DFIG and its associated converter system have to be protected against severe grid faults with considering proper converters and crowbar switching. Alternatively, the FRT can be achieved by applying the advanced nonlinear control theory, including state feedback linearization and the input-output feedback linearization. In this thesis, the sliding mode control theory is applied for FRT enhancement. Both 5th order and the reduced 3rd order DFIG system will be utilized for sliding controller synthesis. Simulations of one-machine-infinite-bus system and a two-area-four-machine system are performed to verify dynamical characteristics of the proposed sliding control. Performance comparisons among existing FRT enhanced control laws will also be examined through numerical explorations

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