本文選題：火電直流孤島運行　切入點：頻率控制　出處：《華北電力大學(北京)》2017年博士論文　論文類型：學位論文

【摘要】：高壓直流輸電(HVDC)因其經(jīng)濟性和快速靈活、高度可控的特點,在大型能源基地向負荷中心的遠距離輸電中應用非常廣泛。若高壓直流輸電運行時的送端系統(tǒng)主要由火電機組(群)組成而與交流主網(wǎng)無電氣聯(lián)系,則稱為火電直流孤島運行,該系統(tǒng)則稱為直流孤島送出系統(tǒng)。直流孤島送出系統(tǒng)有效短路比和轉動慣量小,系統(tǒng)承受擾動能力較弱,存在著頻率穩(wěn)定、過電壓、次同步振蕩等一系列技術問題,造成機組全停和直流閉鎖的可能性大大增加,給含大量熱力生產(chǎn)過程的火電直流孤島運行穩(wěn)定控制、系統(tǒng)和設備安全及工程決策帶來了巨大的困難。隨著我國國內大型火電基地的集中開發(fā)和遠距離外送以及國際電力能源的引進,受當?shù)仉娋W(wǎng)規(guī)模、系統(tǒng)接入條件等因素限制,火電直流孤島系統(tǒng)研究和試驗的現(xiàn)實意義和重要性日益凸顯,而國內外尚沒有火電直流孤島系統(tǒng)的運行經(jīng)驗。以往對于直流孤島系統(tǒng)頻率穩(wěn)定的研究主要依賴于接入實際直流控制保護系統(tǒng)的實時仿真或采用詳細直流控制保護電磁暫態(tài)模型的離線仿真,采用窮舉法進行交直流故障研究從而得到該系統(tǒng)的實際控制效果,采用試探法進行控制系統(tǒng)參數(shù)的優(yōu)化,因而存在耗時長、投入成本高的問題,對于控制穩(wěn)定性結論和認識存在盲區(qū),無法從定性和定量兩方面真正指導工程實踐。本文首先從基本物理概念出發(fā),揭示了火電直流孤島系統(tǒng)頻率特性問題的物理本質,對直流輸電系統(tǒng)、汽輪機組、伺服系統(tǒng)等分別進行了簡化建模,降低了火電直流孤島系頻率控制閉環(huán)系統(tǒng)的階數(shù),從而建立了等效的與實際系統(tǒng)特性一致的火電直流孤島系統(tǒng)傳遞函數(shù)模型,針對火電機組一次調頻、直流附加控制等不同控制策略和參數(shù)配合,基于根軌跡分析進行了火電直流孤島系統(tǒng)的頻率穩(wěn)定性研究及優(yōu)化控制系統(tǒng)參數(shù),揭示孤島系統(tǒng)頻率穩(wěn)定性機理。考慮到電力系統(tǒng)和設備的安全性,實際運行中的火電機組和直流系統(tǒng)的控制復雜性,本文以±500kV呼遼直流輸電工程孤島送出系統(tǒng)為例,建立了反映包括送端系統(tǒng)各發(fā)電機組、交流線路、直流系統(tǒng)等實際特性的詳細準確電磁暫態(tài)仿真模型,通過交直流故障仿真分析,從三個方面研究揭示火電直流孤島系統(tǒng)運行的關鍵性問題,一是穩(wěn)態(tài)或正常操作時滿足電力系統(tǒng)穩(wěn)態(tài)頻率控制指標的要求,二是N-1故障等無安控措施下的火電直流孤島系統(tǒng)恢復能力及頻率波動范圍滿足機組設備等頻率控制要求,三是嚴重故障下配合安控措施的孤島系統(tǒng)頻率穩(wěn)定性問題,并給出了不同控制參數(shù)及配合下的火電直流孤島系統(tǒng)運行條件和運行控制策略。針對直流輸電工程建設發(fā)展過程產(chǎn)生的單臺火電機組與直流系統(tǒng)直接配合啟動的需求,考慮汽輪機組、直流系統(tǒng)等各方面設備的能力和安全問題,研究了二者配合啟動過程中由于響應特性不同而產(chǎn)生的頻率穩(wěn)定性問題。由于火電機組并網(wǎng)運行時鍋爐及汽輪機的限制,很難在并網(wǎng)時初負荷從零直接提升配合啟動直流,因此論文從兩方面考慮,綜合解決直流啟動對火電機組并網(wǎng)初負荷的要求:一是采取措施進一步降低直流啟動功率,另一方面提高機組帶初負荷的能力,并對不同汽輪機組控制器的啟動效果、機組與直流配合時間等方面進行了仿真論證。本文提出的研究方法為后續(xù)直流工程建設和運行中可能出現(xiàn)的孤島運行方式的選擇奠定了理論基礎,為未來大型火電基地的集中開發(fā)和遠距離外送提供了技術依據(jù)。
[Abstract]:High voltage direct current transmission (HVDC) because of its economy and fast and flexible, highly controllable, applied to long distance transmission load center in a large energy base in a very wide range. If the end system send HVDC when operating mainly by thermal power units (Group) and no electrical connection and the communication network is called power DC islanding operation, the system is called DC system. Effective short Island sent DC Island sending system ratio and small inertia, system under disturbance ability is weak, there is a stable frequency, voltage, a series of technical problems of subsynchronous oscillation, resulting in the possibility of unit full stop and DC blocking DC power to greatly increase the island contains a large number of thermal stable operation control of the production process, decision-making system and the safety of the equipment and engineering has brought great difficulties. With the focus on the development of the domestic large-scale thermal power base in China and far From the delivery and the introduction of international power, by the local power grid scale, restricting system access conditions and other factors, practical significance and importance of the research and test of DC system of power island has become increasingly prominent, and there is no operating experience in power system. The isolated DC DC frequency stabilization for the study of the islanding system mainly depends on the line the simulation of real-time simulation of actual HVDC control and protection system access or use with DC control protection electromagnetic transient model, using exhaustive method to study fault in DC to obtain the actual effect of this system, optimize the parameters of control system using heuristics, which are time-consuming, high cost problems, for the control of stability and conclusion unable to recognize the existence of blind spots, from two aspects of qualitative and quantitative real engineering practice. This paper begins from the basic physical concepts Starting, reveals the physical essence of the frequency characteristics of DC power system islanding problem, the DC transmission system, steam turbine, servo system were simplified modeling, reduce the power system frequency control DC order Island closed loop system, and established the equivalent with the actual system characteristics consistent power DC islanding system transfer function model for a time, frequency and power units, with the additional DC control of different control strategies and parameters, root locus analysis and optimization are studied based on the frequency stability of power system islanding DC control system parameters, to reveal the frequency stability of islanding system mechanism. Considering the safety of power system and equipment, control the complexity of the actual operation of the thermal power unit and DC system, taking 500kV + Hulunbeier Liaoning HVDC Island sent system as an example, including the sending end system is established to reflect the All the generating units, the AC line, with accurate electromagnetic transient simulation model of the actual characteristics of DC system, the DC fault simulation analysis, from three aspects of key problems of power system operation of DC Island, is a power system to meet the requirements of steady steady frequency control or normal operation, the two is N-1 no fault in power system security control measures under DC Island recovery and frequency fluctuation range to meet the unit frequency control requirements, the three is the frequency stability problem with islanding system under severe faults control measures, and gives the power control system of DC island operation conditions and operation strategy of different control parameters and with single power. The unit and the DC system for DC transmission project development process directly with the needs of start, consider the steam turbine unit, DC system The ability and safety problems and other aspects of equipment, on the two with the start process due to the frequency stability problem caused by different response characteristics. Because of boiler and turbine thermal power units connected to the limit, is very difficult in the network initial load from zero start with DC Direct promotion, so this paper in two aspects, comprehensive to solve the requirements of DC starting load thermal power grid at the beginning: one is to take measures to further reduce the DC power to start, on the other hand, improve the unit load capacity with initial, and the controller of different turbine starting unit and DC effect, with time and other aspects of the simulation verification. The research method for islanding operation possible follow-up HVDC project in construction and operation choice laid a theoretical foundation for the future focus on the development of large thermal power bases and distance from outside The delivery provides a technical basis.

【學位授予單位】：華北電力大學(北京)
【學位級別】：博士
【學位授予年份】：2017
【分類號】：TM712;TM732

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本文編號：1649434