船舶中壓直流配電系統之穩態穩定度分析

Steady-state Stability Analysis of Medium Voltage DC Distribution Systems for Marine Vessels

中壓直流（medium voltage DC）配電系統為一種新的船舶供電技術，近年來廣受許多船廠及船東討論及研究。由於這類配電架構具備不同類型的電力轉換器且系統中同時存在交流（AC）及直流（DC）配電，系統之穩態穩定度（steady-state stability）問題變成相當重要，透過電力潮流（power flow）計算可分析這類的問題。本文主要目的是建立一套整合電力轉換器之船舶中壓直流配電系統之穩態穩定度分析模式。首先考慮船上中低壓操作特性來推導交／直流電力轉換器在穩態下之電力潮流精確數學模型，接著利用牛頓拉弗森演算法來發展一體化交／直流電力潮流（unified AC／DC power flow）分析模式，同時求解交流及直流系統與交／直流介面匯流排之潮流方程式，作為系統規劃使用。藉由所發展的分析模式，不同發電機與電力轉換器之連接架構於特定負載及發電資料與電力轉換器控制設定下之發電／配電設備與電力轉換器之穩態運轉參數可以被正確地計算出來，以決定適當的供電連接架構與電力轉換器控制設定，維持系統穩態穩定度。 Medium voltage DC (MVDC) distribution systems that are a novel technique for marine vehicles have been extensively studied by ship building corporations and owners in recent years. In this type of distribution systems, the steady-state stability issue is important because of the presence of different types of power converters and both of AC and DC service powers in the system. Power flow analyses can be carried to address this issue. This paper aims to build a set of analysis model for steady-state stability of ship MVDC distribution systems with power converters. A rigid power flow model of the power converters in steady-state is first derived to consider medium and low voltage characteristics of electric power system on this type of ship. A Newton-Raphson algorithm based unified AC/DC power flow solution model then is developed to incorporate AC-system and DC-system models and the AC/DC interface buses for system planning purpose. With the developed analysis model, the steady-state operating parameters of the power-generation/distribution equipment and power converters under different connection configurations of power generator and converter for a given set of busbar loads, power generations, and power converters can be accurately calculated for determining proper service power connection schemes and power converter settings for maintaining system steady-state stability.