本文選題：電網換相換流器高壓直流輸電　切入點：電壓源換流器高壓直流輸電　出處：《西南交通大學》2017年碩士論文　論文類型：學位論文

【摘要】：電網換相換流器高壓直流輸電(LCC-HVDC)憑借其經濟性、穩(wěn)定性、快速可控性以及可實現電網異步互聯(lián)等諸多優(yōu)勢,在我國的"西電東送"戰(zhàn)略中起到了至關重要的作用。隨著大功率全控型電力電子器件的進步和規(guī)�；稍偕茉吹拈_發(fā),電壓源換流器高壓直流輸電(VSC-HVDC)也得到了快速發(fā)展。近年來,由LCC-HVDC和VSC-HVDC構成的混合雙饋入直流輸電系統(tǒng)受到了越來越多的關注與研究。接地故障作為電力系統(tǒng)最常見的故障之一,一直是直流輸電系統(tǒng)故障保護策略研究關注的重點。目前為止,還沒有針對混合雙饋入直流系統(tǒng)接地故障特性及其保護策略的系統(tǒng)研究。本文首先針對LCC-HVDC和VSC-HVDC兩種直流輸電系統(tǒng)分別建立了數學模型,設計出相應的控制策略,并仿真驗證了控制策略的有效性。在此基礎上,建立包含LCC-HVDC和VSC-HVDC的混合雙饋入直流系統(tǒng)的電磁暫態(tài)系統(tǒng)模型。隨后,選取混合雙饋入直流系統(tǒng)中的LCC-HVDC子系統(tǒng)整流側、VSC-HVDC子系統(tǒng)整流側及混合雙饋入直流系統(tǒng)逆變側這三個主要區(qū)域作為研究對象,針對區(qū)域內的主要接地故障進行仿真分析,并對故障機理進行研究。對于混合雙饋入直流系統(tǒng)中VSC-HVDC子系統(tǒng),針對不對稱接地故障導致的換相電壓三相不平衡情況,設計基于VSC系統(tǒng)無源性及其歐拉-拉格朗日數學模型的正序、負序無源控制器。仿真結果表明,該控制器的動穩(wěn)態(tài)控制特性良好。在此基礎上,設計改進的定有功功率控制以保證故障狀態(tài)下VSC-HVDC子系統(tǒng)的有功功率穩(wěn)定輸出。仿真結果表明,該方法有效地控制了故障電流增幅。
[Abstract]:LCC-HVDCs have many advantages, such as economy, stability, fast controllability, asynchronous interconnection and so on. It has played an important role in the strategy of "power transmission from west to east" in China. With the development of high-power fully controlled power electronic devices and the development of large-scale renewable energy, Voltage source converter (HVDC) VSC-HVDC) has also been developed rapidly. In recent years, the hybrid double-fed DC transmission system composed of LCC-HVDC and VSC-HVDC has attracted more and more attention and research. Grounding fault is one of the most common faults in power system. It has always been the focus of research on fault protection strategy of HVDC transmission system. There is no systematic research on grounding fault characteristics and protection strategy of hybrid double-fed DC system. Firstly, mathematical models of LCC-HVDC and VSC-HVDC DC transmission systems are established, and corresponding control strategies are designed. The simulation results show the effectiveness of the control strategy. Based on this, the electromagnetic transient system model of a hybrid double-fed DC system including LCC-HVDC and VSC-HVDC is established. Three main areas of LCC-HVDC subsystem rectifier side VSC-HVDC subsystem and inverter side of hybrid double-fed DC system are selected as the research object, and the main grounding faults in the region are simulated and analyzed. And the fault mechanism is studied. For the VSC-HVDC subsystem in the hybrid double-fed DC system, the three-phase voltage imbalance caused by the asymmetrical grounding fault is considered. Based on the VSC system passivity and its Euler-Lagrangian mathematical model, a positive-order and negative-sequence passive controller is designed. The simulation results show that the controller has good dynamic and steady-state control characteristics. An improved constant active power control is designed to ensure the stable output of the active power of the VSC-HVDC subsystem under the condition of failure. The simulation results show that the proposed method can effectively control the increase of the fault current.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM721.1

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