船舶中压直流综合电力系统短路特性与分层协调保护策略研究

Shipboard Integrated Power System (IPS) is the mark of an all-electric ship. As the trend of shipboard IPS, medium-voltage DC (MVDC) IPS has several special characteristics, such as the particularity of facilities in it, the complexity of power network structure, the tight coupling of AC and DC electric power. These particularities would result in inapplicability of short-circuit characteristics analysis and protection strategies for traditional power system. Aiming at the issue, the project firstly divides the MVDC IPS into networks of three levels, i.e. distributed MVDC transmission network, DC zonal electrical distribution network, radial low-voltage AC distribution network. Secondly, short-circuit dynamic characteristics and their transmitting rules of distinct networks are concluded through researches on two aspects, i.e. analytic computation of dynamic characteristics of MVDC transmission network powered by twelve-phase rectified generators with a sudden positive-to-negative fault, mathematical modeling of dynamic characteristics of MVDC IPS with a ground fault. Thirdly, theoretical systems of hierarchical coordinated protection strategies of whole MVDC IPS are formed, and a principle prototype for system protection are developed through researches on three aspects, i.e. protection strategies of MVDC IPS under positive-to-negative and line-to-line short-circuit faults, detection and identification methods of MVDC IPS under ground faults, protection matching among networks of distinct levels. Achievements of the project will not only provide theoretical support for the design and safe operation of shipboard MVDC IPS, but also can be widely applied to all types of land power systems containing huge amounts of power electronic devices.

船舶综合电力系统是全电船舶的标志，中压直流综合电力系统是船舶综合电力系统的发展方向。针对中压直流综合电力系统组成设备特殊、电网结构复杂、交直流紧耦合等特点导致传统电力系统的短路特性分析与保护策略无法适用的问题，本项目将中压直流综合电力系统划分为分布式中压直流输电网、直流区域配电网、辐射状低压交流配电网三个层次网络，通过研究十二相整流发电机供电的中压直流输电网正负极间短路动态特性的解析计算、中压直流综合电力系统接地短路动态特性的数学建模，得到系统不同层次网络的短路动态特性及其传递规律；通过研究中压直流综合电力系统的极间/相间短路保护策略、接地短路故障检测与定位方法，以及不同层次网络的保护匹配性，形成全系统的分层协调保护理论体系，并研制系统保护策略原理样机。项目成果不仅可为船舶中压直流综合电力系统的设计和安全运行提供理论支撑，还可推广应用于陆用各型电力电子化的电力系统。

中压直流综合电力系统是船舶综合电力系统的发展方向，针对其组成设备特殊、电网结构复杂、交直流紧耦合等特点给系统故障保护带来的挑战，本项目开展船舶中压直流综合电力系统极间/相间/接地短路特性建模分析与分层协调保护策略研究。在中压直流网极间短路特性分析方面，建立了十二相整流发电机供电系统极间短路动态的数学模型，提出了极间短路电流的解析计算方法，并进行了试验验证。在接地短路特性分析方面，建立了含典型电力电子装置的直流电力系统接地短路动态数学模型，搭建了全系统接地短路仿真平台，开展了系统接地短路特性仿真分析及试验验证。在极间/相间短路保护策略方面，提出了变工况整定的中压直流输电网极间短路保护策略、改进方向闭锁过电流保护的低压交流配电网相间短路保护策略，研究了不同层次网络保护的匹配性设计。在接地短路的检测与定位方面，提出了一种基于附加接地电阻的中压直流主网接地故障保护方法，仿真验证了其保护方法的有效性。项目成果不仅可为船舶中压直流综合电力系统的设计和安全运行提供理论支撑，还可推广应用于陆用电力电子化的电力系统。