An In-Depth Study of Complex Power System Dynamic Behavior Characteristics for Chinese UHV Power Grid Security

In this paper,a series of major policy decisions used to improve the power grid reliability,reduce the risk and losses of major power outages,and realize the modernization of 21st century power grid are discussed. These decisions were adopted by American government and would also be helpful for the strategic development of Chinese power grid. It is proposed that China should take precaution,carry out security research on the overall dynamic behaviour characteristics of the UHV grid using the complexity theory,and finally provide safeguard for the Chinese UHV grid. It is also pointed out that,due to the lack of matured approaches to controll a cascading failure,the primary duty of a system operator is to work as a "watchdog" for the grid operation security,eliminate the cumulative effect and reduce the risk and losses of major cascading outages with the help of EMS and WAMS.

Contribution of UHV Grid to United National Power Market

Power market construction is an important part of the marketization reform in China's electric power industry and an essential part of the economic system reform in China. With the social and economic development, the contradiction between distribution of energy resources and development of regional economies gets increasingly noticeable, and a united national power market is consequentially required to optimize the allocation of energy resources over the whole country. Analyses indicate that the development of UHV grid will provide a strong material support for the united national power market by expanding market coverage, lowering load fluctuation and promoting diversif ication of power resources.

Influencing Factors of the Power Fluctuation on the Ultra High Voltage Transmission Line Caused by Faults at the Remote Ends of the Interconnected Grid

After the North China grid and the Central China grid get into connection with the UHVAC demonstration, a new phenomenon is discovered according to some simulations. That is, the faults at the remote end of the UHV interconnected grid will result in significant power fluctuation and voltage drop on the UHV transmission line and even system splitting. But the faults near the UHV line only have marginal effects. Further, the simulation results also indicate that the short-circuit current of the buses near the UHV line is larger than that of the buses far away from the UHV line. This phenomenon is divergent from the traditional view. In this paper, the detail will be introduced, and the factors influencing the system stability after faults are presented and analyzed. The results indicate that transmission power of the UHV line and of the lines between the remote end and the major grid influence the fluctuation on UHV line. The load model and the grid structure of the remote end also have effect on it. Finally, corresponding control scheme is presented to improve the operation conditions of the UHV interconnected grid and ensure its security and stability.

Influence and hazard of disastrous space weather on power grid in China

Based on the measured data of geomagnetically induced currents （GIC） in Guangdong Ling＇ ao 500 kV power networks during several magnetic storms at the peak years of 23rd Solar Cycle, the GIC calculation results of 750 kV planning power grid in Shartxi, Gansu, Qinghai and Ningxia, the structure and characteristics of power networks from 500 kV to 1 000 kV, and super magnetic storm in 1859 are analyzed in this paper. Through the analysis, the possible impacts of extreme space weather on the future ultra-high voltage （UHV） grid, the security of large-scale power system in China are expounded, and the research suggestions coping with the strong solar storms are proposed.

China Needs Prompt Construction of a Strong National Power Grid (Excerption)

China needs to develop a strong national power grid which takes ultra-high-voltage (UHV) transmission systems as its core. The grid is expected to adopt 1000-kV-class AC and ± 800-kV DC transmission systems. In view of significant achievements in technological research and considerable progress in UHV manufacturing technology, China is capable of developing UHV systems. In order to promote the construction of UHV systems,China Electric Power Research Institute and other institutions have initiated first-phase research activities of UHV transmission technologies. The main contents involve research on UHV transmission technology and its economy,developing and manufacturing abilities on UHV equipment, prospective of UHV network frame and selection of demonstration projects, etc.

Component Analysis and Calculation for Social Benefits of UHV Assessment

With the rapid development of the UHV power grid, evaluation of the economic and social benefits of the UHV power grid is conducive to guiding the planning and construction of UHV power grid. At present economic benefit evaluation system of the UHV power grid is driving to maturity stage on the whole at home and abroad, but it invariably tends to regard social benefits as part of economic benefits, without evaluating social benefit separately. The social benefit evaluation model of UHV power grid is built in case of sufficient investigation. The differentials between social benefit and social cost are calculated respectively by three kinds of solutions according to the constructed social cost evaluation index system and social benefits evaluation index system, conclusion that UHV power grid transmission has better social benefits can be reached by contrastively analyzing the social three kinds of solutions corresponding to benefits. At last, the evaluation model and method are verified and analyzed through the analysis of engineering projects.

Research on the Anti-corona Coating of the Power Transmission Line Conductor

An anti-corona method for the power transmission lines is proposed in this paper. The RTV coating is used as the anti-corona coating, which is spaying onto the surface of the wearing conductor. The corona characteristic of the conductor test was done, and the corona onset voltage increase after the spraying of the anti-corona layer, the corona loss in the same voltage decrease, which could prove the excellent effect of improving the corona characteristic of the conductor. This anti-corona method will have great prospect, based on the background of the construction of UHV power transmission lines.

特高压直流接地极选址及受端电网结构偏磁电流抑制策略研究

常规的特高压直流接地极选址及受端电网结构偏磁电流抑制方法主要使用CDEGS软件确定电流抑制修正关系,易受接地极电位差变化影响,导致不同测点的偏磁电流过高,因此需设计一种特高压直流接地极选址及受端电网结构偏磁电流抑制策略。根据地质构造及断裂关系生成特高压直流接地极选址流程,设计受端电网结构偏磁电流抑制算法,从而完成特高压直流接地极选址及受端电网结构偏磁电流抑制。实验结果显示设计的直流接地极选址及电网结构偏磁电流抑制策略的各个测点的偏磁电流较小,表明该策略抑制效果较好、可靠性高,有一定的应用价值。

超(特)高压串联补偿控制保护系统与线路保护接口方案

超高压串联补偿(以下简称串补)装置在国内应用时间相对较短,在实践中其与线路保护接口策略方面暴露出的一些问题值得改进。结合超(特)高压电网现状,探讨串补自动重投与线路重合闸配合方案。针对某特高压变电站高压电抗器保护和失灵保护不能退出本站串补装置问题,提出断路器操作箱三相跳闸接点启动退出串补方案和线路保护收远传开关量输入信号启动退出串补方案;并针对目前存在的串补热备用时线路单相瞬时故障串补自动重投问题,提出将线路过电压远传功能集成于线路保护装置的构想,引入全新的"线路失灵"保护理念,并提出一种全新的串补型线路保护方案。

基于改进型相关法的单相自适应重合闸新判据

分析了超、特高压输电线路发生单相瞬时性及永久性接地故障时断开相电压的形成机理,指出瞬时性单相接地故障时断开相计算电压与两健全相电压和沿线变化规律的相似程度远大于永久性接地故障时的相似程度,并在此基础上,提出利用改进型相关法的故障性质识别新判据。该判据综合考虑了断开相计算电压与两健全相电压和的幅值与相位的相似性,使瞬时性故障时的相关系数大于永久性故障时的相关系数。该判据实现简单,高阻接地时仍具有较高灵敏度,且受线路长度、负荷电流及故障距离的影响很小,适用于不带并联电抗器的超、特高压输电线路。大量仿真实验验证了所得结论的正确性。

华北—华中—华东特高压同步电网构建和安全性分析

总结了国内外电网的发展趋势和经验。结合中国电源和负荷的分布特点,提出了中国同步电网受端规模、电压等级、输电方式和华北—华中—华东特高压(ultra high voltage,UHV)同步电网的安全构建原则。分析了大规模同步电网的安全稳定特性和大电网停电机制,论证了规划中的华北—华中—华东特高压同步电网的安全性。

超特高压输变电设备的覆冰试验技术

鉴于超特高压输电线路面临覆冰问题越来越突出,必须建立有效的覆冰试验技术和手段以开展超特高压覆冰机理、外绝缘特性和防冰除冰新技术研究。为此,在介绍了国内外覆冰实验室及覆冰试验技术现状并解决了超特高压覆冰试验所面临的带电覆冰、高海拔低气压环境、大容量试验电源等问题后建成了特高压交流试验基地环境气候实验室。多项课题试验证明环境气候实验室具备超特高压输变电设备覆冰试验能力,为开展覆冰外绝缘特性、在线监测和预警技术,融冰、除冰技术,防冰冻新材料应用等防冰减灾课题研究创造了良好的试验平台。

特高压同步电网安全性论证

根据《电力系统安全稳定导则》,从短路电流、静态安全性、暂态稳定性、动态稳定性等方面,校核了特高压同步电网方案的安全稳定性;根据《电力安全事故应急处置和调查处理条例》要求,校核了可能发生的自然灾害导致的电网严重故障下,特高压同步电网的承受能力及可采取的措施;根据第3道防线的设置原则和要求,分析了由低频减载、低压减载和解列控制构成的第3道防线在特高压同步电网的适应性。结果表明,特高压同步电网安全性满足《电力系统安全稳定导则》的要求,承受严重故障能力强,第3道防线可有效控制事故范围,避免出现大停电;采用基于广域同步量测信息的自适应解列、交直流协调控制等技术可以进一步提高系统的安全性。

特高压远距离大容量云电送粤中的稳定问题研究

云电送粤特高压直流输电嵌入交流系统运行,将使送端云南电网面临诸多挑战,其中涌现出的若干稳定问题将对送端电网的安全稳定运行产生重大的影响,亟待深入的分析和研究。介绍了送端云南电网的特点,并分析了云广特高压系统投运后,云南电网将面临交直流相互影响、直流潮流转移导致的电网稳定问题以及送端电网的高周问题。提出针对这些问题的部分研究思路和内容,包括建立全电磁暂态仿真平台开展交直流相互影响的研究;从暂态稳定、电压稳定和低频振荡3方面研究云南电网潮流转移中的系统稳定问题;针对电网高周问题,以机理分析为基础,开展云南电网高周协调控制策略的研究工作。

带并联电抗器的超/特高压输电线路单相自适应重合闸故障性质识别判据

针对带并联电抗器的超/特高压输电线路,提出了通过检测断开相端电压自由分量实现的单相自适应重合闸故障性质识别判据。当自由分量频率可精确计算时,该判据可直接应用于超/特高压输电线路中,且具有较高的灵敏度。若自由分量频率计算误差不超过10%,则该判据应用于超高压输电线路与自由分量频率低于45Hz的特高压输电线路中时可快速准确地判断故障性质。采用频率计算误差补偿算法后,该判据适用于所有的超/特高压输电线路,且灵敏度高,判断速度快。该判据的性能受自由分量频率估算误差的影响。大量仿真实验验证了所得出结论的正确性。

特高压电网社会效益分析及评价方法

引入全寿命周期成本和影子价格理论,识别特高压电网成本和社会经济效益组成;并基于与效益相关的各元素影子价格估算公式,深入分析除售电收益外特高压电网所带来的巨大的社会效益。编制投入产出效益流量表,建立基于全寿命周期成本的特高压电网社会效益评价指标;结合灵敏度分析理论,形成适用于特高压电网的社会效益评价方法。以我国某特高压同步大电网2020年规划方案为算例,对比分析了在传统财务成本和考虑全寿命周期成本计算方式下的社会效益评价结果,验证了所提方法的有效性和可行性。

带并补电抗器超/特高压输电线路单相瞬时故障拍频特性研究

以带并联电抗器补偿的线路为研究对象,深入剖析了单相瞬时故障消失后产生拍频现象的机理和条件,探讨了瞬时故障低频自振分量的频率及幅值衰减特性,以及断开相电气量无显著拍频现象产生的条件。研究结果表明:故障电气量中产生明显拍频现象的条件为瞬时故障且电弧可靠熄灭,但部分瞬时故障由于工频和低频量幅值差过大、频差过小或低频自振分量幅值衰减过快,导致断开相电压与电抗器电流没有明显拍频现象,此时可采用非拍频特征判据实现故障性质识别。大量ATP仿真与物理实验模型仿真验证了上述理论分析的正确性。

西北电网短路电流的限制措施

介绍了电力系统短路电流产生的原因和危害以及国内外在电力系统短路电流限制技术方面的研究状况,结合西北750 kV电网的建设和发展,分析了西北电网在750kV发展过程中短路电流增加的原因和趋势,并对限制短路电流的多种措施进行了探讨:包括实现电网分层分区运行;加装中性点电抗;实现母线分段运行;采用高阻抗变压器等。针对不同的网架情况,提出了相应的对策和建议。

我国未来同步电网构建研究

在对我国同步电网现状分析的基础上,结合我国特高压电网发展规划情况,提出了“十二五”初期和2020年前后我国同步电网构建方案。对华北一华中一华东特高压同步电网的合理性、技术可行性以及电网综合效益进行了分析。

超/特高压输电工程典型间隙操作冲击放电特性试验研究综述

在超/特高压输电工程的设计中,空气间隙的选择非常重要,可以影响输电线路中杆塔的尺寸,以及变电站或换流站中各种带电结构之间的距离。空气间隙的合理设计既关乎系统的安全稳定运行,又直接影响到工程的造价。一般情况下,与工频、直流或雷电过电压相比,耐受操作过电压所需的空气间隙最大,因此,杆塔和变电站或换流站中典型空气间隙的操作冲击放电特性是影响输电工程安全性和经济性的重要因素之一,也是超/特高压交直流输电工程设计的主要依据。操作电压下空气间隙的放电特性与电极的形状、电极间的距离、施加电压的波形等因素有关。通过对国内外空气间隙在操作冲击电压下的试验研究进行综述,包括各种典型间隙的操作冲击放电特性以及影响该特性的各种因素,从而为今后更加深入地研究操作冲击放电特性提供借鉴。