变电站自动化技术的未来发展(二)——集成自动化、寿命周期成本

讨论了变电站的高压设备智能化对其自动化的影响,介绍了变电站集成自动化系统的基本结构,分析了可靠性和经济效益,指出降低变电站寿命周期成本是发展高压和超高压变电站集成自动化系统最重要的推动力。     

变电站自动化技术的未来发展（一）——电力市场与协调型自动化

电网发展和电力市场化对变电站,特别是高压、超高压变电站自动化系统在功能、可靠性、经济性方面均提出了新的要求,随着计算机技术、通信技术和网络技术的发展,变电站自动化系统将向集成化方向发展。文中介绍了各个独立的控制、保护和监测设备通过局域网在变电站层集成为协调型自动化系统的基本结构;除保护和控制外,将设备的状态监测也纳入自动化系统功能;同时对该系统相应的技术支持进行了分析;介绍了日本已投入运行的类似变电站系统的运行经验。     

特高压变电站工频电场模拟计算及其分布规律

特高压变电站内设备种类繁多,且电磁环境较为复杂,因此在设计阶段需对站内工频电场强度进行合理评估。为此,运用有限元分析软件Ansys建立了3维变电站计算模型,并采用谐波分析方法实现了电准静态场的模拟计算。以淮南至上海特高压交流输电示范工程变电站带高抗出线回路新型4柱设计方案为例,研究了母线、设备及构架对回路对地1.5m处电场分布的影响,并对母线高度进行了优化。研究结果表明：带高抗出线回路（简称高抗回路）的大部分区域对地1.5m处的电场强度由母线高度决定,设备结构仅对自身附近区域的电场强度影响较大;构架位置会影响站内电场强度峰值的出现区域;设计方案的母线高度为17.15m,最大电场强度为9.34kV/m,经过优化的母线的最优高度为16.65m。对特高压交流示范工程长治站和荆门站分别进行工频电场模拟计算,计算结果表明：2座变电站的工频电场均满足电场强度设计要求;站内主要区域电场分布的计算结果和测量结果之间的误差约为10%。     

Line Arresters Application in Lightning Protection of High Voltage Substations with Non-standard Configuration

In this paper, application of gapless transmission line arresters (TLAs) in substation lightning protection is analyzed. Deterministic calculations in accordance with IEC 62305 are performed. Substations with non-standard configuration equipped with Gas Insulated Switchgear (GIS), long cables, and a direct cable connecting GIS and power transformer are considered. It is concluded that 220- and 400-kV substations lightning performance can be significantly improved by using TLAs at only one or two overhead line towers in front of the substation. In some cases, TLAs provide better lightning protection of power transformer than surge arresters installed in GIS. Positive effects of TLAs application are noticed both in the case of back-flashovers and in the case of shielding failures. TLAs energy stress increases with the decrease of the system rated voltage. Maximum estimated values in the analyzed substations are below 2.5 and 0.5 kJ/kVr for TLAs installed in 220- and 400-kV systems, respectively.     

河北省南部电网输变电工程可听噪声测量与分析

结合河北省南部电网实际情况,选取16座变电站作为输变电工程可听噪声测量的调查对象,对变电站的变压器、高压电抗器、带电构架、站界及噪声敏感点的可听噪声进行测量,结果表明各变电站的主要噪声源为变压器,变电站内声源的主频段噪声大多为低频噪声,并分析不同电压等级变电站的噪声特点,为噪声综合治理提供依据。     

Generalized charge simulation method for the calculation of the electric field in high voltage substations

This paper deals with the calculation of the electric field strength in high voltage (HV) substations comprising complex geometrical structures. Generalized charge simulation method is proposed for improving the precision of the calculation of the electric field strength. The objective of this analysis is to examine the influence of towers, HV apparatus and fences on the spatial electric field distribution. For this purpose, a three-dimensional generalized model of HV substation has been developed, including phase conductors, bypass busbars, HV apparatus, fences and towers (denoted as Full model). The obtained results of the calculation of the electric field strength are compared with the Simplified model, which only includes phase conductors connected to HV network. Verification of the proposed Full model performed by comparing the calculated and in-field measured values of the electric field strength within HV substations and in their vicinity gives very promising results.     

Development of an advanced voltage control technique to improve voltage and reactive power characteristics of a large-scale power cable system

The power supply system for a metropolitan area consists of multiple 275-kV power cable systems to supply power to a large number of consumers. Each system has a large charging capacity (capacitive reactive power). When 275-kV power cable systems experience a voltage drop, their charging capacity decreases. However, the reactive power losses increase in the 275-kV overhead transmission lines, which supply large power to power cable systems, thus causing the performance of the power supply system to deteriorate. In this paper, the following three points are reported:

• 1 When the secondary power system of the trunk substation is a large-scale power cable system, new techniques can greatly improve the voltage and reactive power characteristics by controlling the rise of the sending-end voltage at the secondary side of the trunk substations and maintaining the voltage of power cable systems at a constant level.
• 2 In the use of this control technique, it has been demonstrated that controlling by the direct-detecting method of a voltage drop in the primary power system is superior to one that controls by the indirect-detecting method, which increases load power in the cable system.
• 3 The results of simulations obtained by using a 275-kV cable system model and a performance power system model show that the use of this control technique can produce a good effect despite the allowances made for the opposite effect, i.e., a decrease in the capacity of power capacitors resulting from voltage drop at the tertiary voltage of a 500-kV transformer.

This study is carried out to examine the possibility of lightning control using a photoionized plasma produced by a UV laser without an optical air breakdown. As the fundamental experiment, the characteristics of a laser-triggered spark gap (LTSG) are examined, where a laser beam is not irradiated on the surface of the electrodes. In this experiment, the KrF excimer laser is very effective in increasing the plasma density n_e and the reduction ratio p of 50 percent breakdown voltage against the self-breakdown voltage. The relation between n_e and p is increased by generating a long and high-density plasma parallel to the discharge axis. On the other hand, the abnormal discharge process in triggered lightning using a rocket is examined, and it is indicated that the most important condition to trigger a lightning discharge is the production of a plasma channel of length 200 m and density about 10¹⁹ m^?3. It is suggested that such a plasma channel could be produced by a KrF excimer laser with an energy of only about 3.67 J.     

750kV 官亭变电站综合自动化系统的现场检验探析

综合自动化系统是超高压变电站的重要组成部分,规范开展变电站综合自动化系统检验,是确保超高压变电站安全稳定运行的重要环节。对750 kV官亭变电站综合自动化系统现场检验的具体开展情况进行了阐述,从遥测、遥信、SOE分辨率、系统性能、遥控、同期六个项目的测试方法入手,结合相关规程要求和目前系统中检验仪器的使用,对变电站自动化系统检验进行探讨。     

Computation of Electric Fields Using Ground Grid Performance Equations

This paper presents a methodology for calculating electric fields in EHV transmission lines and substations using ground grid performance equations. The computed values proposed by our method compare very favorably with the experimental data published in the literature. The effectiveness of the shielding wires in the UHV transmission lines entering into a substation is investigated. Phase sequence of superposed busbars is also considered. The presence of urban residential buildings near EHV transmission lines is analyzed.     

TRVs and fault clearing stresses in extra-high-voltage radial networks

To cope with the high rate of increase of power demand in the main industrialized districts in Japan, 550-kV transmission systems covering the districts have been reinforced, with most of the main power plants connected directly to these systems. Through 550-/300-kV substations, the majority of power to the districts is supplied by 300-kV systems. To limit the excess short-circuit capacity in the 300-kV systems, they tend to be reconstructed as so-called radial networks. In radial networks with high short-circuit capacity and relatively small number of transmission lines connected to the substation busbars, the rate of rise of TRV can be far higher than standard value. This paper analyzes the transient recovery voltages (TRV) in such extra-high-voltage radial networks in Japan, together with the relevant stresses to circuit-breakers during fault clearings. Future system conditions have also been introduced. As the typical rate of rise of the TRV values, more than twice that of today's standard ones are probable.     

Anhui Province will build lOoo-kV-class UHV passageway

On July 26, The State Grid Corporation （SG） held a symposium on construction of trans-regional network projects in Yinchuan, Ningxia. The construction planning of Northwest China＇s upside-down A-shaped 750-kV backbone network was publicized at the meeting for the first time.     

基于Voronoi图的变电站优化规划方法

对大电网高压变电站的优化选址及其供电区域的自动划分进行了研究。基于V orono i分区的最小距离选址准则,确定了变电站站址及供电区域与V orono i图的对应关系,在满足相关技术约束的条件下,应用最大空心圆策略和V orono i图的局部动态特性,提出了新增变电站的自动定位、供电区域自动划分的优化规划方法,保证了大区域大电网中高压变电站的合理分布,具有宏观指导意义。通过某市220/110 kV网络中变电站优化规划的结果证实了该方法的有效性。     

750kV变电站系统启动分析及安全防范措施

超高压电网启动是一项非常复杂、谨慎的工作,它的安全启动关系着整个电网的安全,因此,必须制定合理、有效的启动方案。笔者以银川东变电站为例,介绍了银川东750 kV变电站及其联网变电站接线系统,全面分析了银川东750 kV变电站启动过程中主要遇到的空载线路合闸过电压、系统继电保护的配置及启动后750/330 kV的电磁环网问题,采取了限制空载线路合闸操作过电压,对继电保护在启动过程中的设置提出了要求,通过控制省级断面潮流等措施降低电磁环网影响。同时也提出了启动过程中应当遵守的安全防范措施,该工程通过了国家电网公司的实际验收,为今后电力系统智能电网的后续发展,特别是超高压电网系统的启动提供了有益参考。     

国内外145～550kV户外高压和超高压组合电器述评

对近期国内外快速发展的户外145～550kV组合电器的基本结构及特点进行了论述,并对145kV紧凑型组合电器与145～550kV插接式智能型组合电器二大系列产品进行了综合分析及比较。重点分析了它们对各种电气主接线的适用范围,以及在我国高压和超高压变电站使用时应充分注意的问题。随着组合电器技术的不断发展和完善,它们将作为介于常规电气设备和气体绝缘金属封闭高压开关设备之间一种新型系列的电气设备,得到非常广泛的应用。     

RF-Based Partial Discharge Early Warning System for Air-Insulated Substations

Partial discharges (PDs) generate wideband radio-frequency interference which can be used for noninvasive monitoring of discharges. This paper presents a novel method based on this principle for PD monitoring of substations. The significant advantage of this method lies in the ability to detect PD sources in energized equipment anywhere within a substation compound during normal operating conditions. The results obtained from the prototypes installed in the U.K. and U.S. substations are reported. Results include correlation with apparent charge and daily recordings obtained before, during, and after the failure of a 132-kV current transformer and 69-kV voltage transformer.      

Comparative analysisof grounding systems formed by MV cable lines with either uninsulated or insulated metal sheath(s)

It is well known that medium-voltage (MV) paper-insulated cables essentially reduce the potentials appearing during a ground fault in substations located in urban surroundings. This is explained by the fact that these cables usually (normally) have an uncoated metallic sheath. Due to this, MV cable lines leaving a high-voltage/middle-voltage (HV/MV) substation act as long external grounding electrodes and spontaneously form one very large and complex grounding system around this substation. Cables with an insulated metallic sheath however, are progressively being more applied in contemporary power distribution practice. Consequently, the following quite logical question arises: how will a cable with such constructive characteristic influence the general conditions for solving the grounding problem of distribution substations, especially of those working in high-voltage (HV) networks with directly grounded neutral(s)? The analysis performed in this paper shows that, when applied these cables spontaneously form a grounding system which also exhibits excellent grounding performances.     

地下金属管道对变电站接地网接地电阻及其测量的影响

城市变电站附近存在大量的地下金属管道,会对变电站接地网的接地电阻及其地面电位分布、接地电阻的现场测试产生较大影响。用基于场路耦合的数值计算方法对变电站接地网和金属管道的散流分布、接地电阻和地面电位分布进行了计算,分析了不同土壤环境下和金属管道是否有防腐层对接地网的接地电阻和地面电位分布的影响,分析了地下金属管道对接地电阻现场测试的影响。结果表明,当金属管道距离接地网越近和金属管道越长时,对接地网的影响越大;金属管道的防腐层能有效降低对接地网的影响;地下金属管道对其沿线附近的地电位影响较大,在现场测试接地电阻时应给以重视。     

750kV高压电抗器笼式出线结构均压特性研究

750 kV变电站内高压电抗器多采用笼式分裂导线与管母连接,该结构形式较为复杂,容易发生严重的电晕放电,既造成功率损耗,又给周围环境带来可听噪声和无线电干扰,因此有必要对高压电抗器出线结构采取一定的防晕措施。采用三维有限元法,对750 kV变电站高压电抗器出线回路进行仿真计算,得出其三维电位及电场强度分布规律,计算笼式出线各分裂导线表面的电场强度分布情况,分析不同屏蔽环配置对其分布的影响,提出高压电抗器笼式出线结构的屏蔽环配置建议。研究成果有效改善了750 kV高压电抗器笼式出线结构的均压特性,已在甘肃白银750 kV变电站的设计和建设中得到应用。     

500 kV变电站站用电源设置方案比较

变电站站用电源的设置方案关系到变电站工程建设投资、运行的可靠性和经济性。目前,站用电源的引接方式有主变低压侧母线引接、站外低压专线引接、站外低压线路T接、高抗抽能线圈和站内高压母线上引接等。这几种引接方式没有绝对的优劣之分,应根据变电站的性质、地理位置及当地电力系统的状况合理选择和组合,既节省投资,又保障变电站安全可靠运行。     

500kV区域控制在线监测数据中心的构建

针对接入南宁区域控制中心的多个变电站在线监测装置不统一,各在线监测系统间缺乏互动,信息不能有效整合的问题,构建南宁超高压区域电网在线监测数据实时监测、分析、预警中心。通过分析在500k V区域控制中心"无人值班,少人值守"的控制模式下,各500k V变电站的分布特征、互联关系,以及在线监测装置的使用状况和软硬件结构,提出在线监测数据中心的建设方法。在线监测数据中心建成后,可实现超高压设备在线监测数据的实时提取、预警发布、专家分析、移动应用,消除了各变电站之间的信息孤岛,提高了信息关联和共享程度,为生产管理提供了有力的决策支持。