In order to implement the “double carbon” goal, China proposes to vigorously develop a new power system with new energy as the main body. Lightning disasters occur from time to time, so the technical requirements for lightning protection of new power systems are getting higher and higher. Compared with a single wind farm or photovoltaic power generation system, the wind-solar hybrid system has more lightning intrusion into key nodes, low tolerance facilities and a larger lightning receiving area. The ATP-EMTP was used to build a transient model of lightning strikes in a wind-solar hybrid system constructed by various subsystems, and the lightning overvoltage distribution of the wind-solar hybrid system was calculated, and the influence of lightning strike location, lightning protection configuration and overhead line length on the overvoltage level of the wind-solar hybrid system was analyzed. The results show that the installation of SPD on the DC side of the PV field inverter achieves the best lightning protection effect for the PV field combiner box, inverter and transformer. The installation of lightning arresters on the high-voltage side of the box transformer of the wind farm can effectively suppress the propagation of the lightning overvoltage at the outlet of the wind turbine to the box transformer; When adopting the single-circuit transmission inlet section, the lightning overvoltage attenuation speed of the photovoltaic farm into the substation bus section is slightly faster than that of the wind farm, and the lightning overvoltage level of the photovoltaic farm inlet section is higher than that of the wind farm inlet section as a whole; The overall lightning overvoltage amplitude of the double-return line section of the same tower is higher than that of the single-return overhead line section. Therefore, when the single-circuit transmission line is adopted, the insulation level of the incoming line of the photovoltaic farm can be appropriately improved, and the length of the bus connecting the wind farm into the substation can be appropriately extended compared with the photovoltaic farm. When the double-circuit transmission line of the same tower is used to integrate into the substation, compared with the single-circuit transmission line, the lightning protection performance of the transmission line can be appropriately improved to reduce the lightning overvoltage amplitude in the intrusion station.)

Aiming at the problem of unsatisfactory identification of transmission line fault diagnosis based on transient current traveling wave, a time series denoising method based on the combination of CEEMDAN and Pearson's correlation coefficient with a feature extraction method is proposed to realize the accurate diagnosis of transmission line fault types. First, the original transient current traveling wave signals collected by the distributed fault monitoring system of the transmission line are decomposed by CEEMDAN to derive the IMF components, and then by calculating the correlation coefficients of each IMF component, the IMF components with lower correlation are discarded and the original signals are reconstructed. Finally, the XGBoost machine learning model is used to identify the reconstructed signal and realize the fine diagnosis of transmission line faults. Comparison experiments with different models show that the method proposed in this paper has better diagnostic effect.

In order to reduce the impact of dense transmission channel outages due to lightning strikes on the operational safety of the power system, this paper proposes a framework of active defense dispatching strategy for dense transmission channel based on lightning warning information. We first establish a comprehensive evaluation model of transmission line unexpected outages based on analytic hierarchy process, then rank the importance degree of the line according to the comprehensive impact index, and fuse it with lightning warning information to provide an essential basis for predicting the set of scenarios. Second, a preventive-emergency two-stage stochastic optimal dispatch model is established to carry out power flow transfer in the preventive dispatch stage and take load shedding to reduce outage losses in the emergency dispatch stage. Finally, a case study verifies that the proposed method is effective in reducing the total system losses in case of dense transmission channel outages due to lightning strikes. 1 1 Supported by Science and technology program of SGCC (State Grid Corporation of China): Research on intelligent monitoring and protection capability improvement technology of UHV dense channel to cope with extreme environmental conditions (524625210017).

Large-scale new energy is mainly based on offshore wind farms in the southeast coast,wind farms in the northwest and photovoltaic power plants,and the access of new energy in these areas to the large power grid system directly leads to a variety of transient overvoltages.In order to solve this kind of overvoltage problem,this paper,from the perspective of DC and AC access of large-scale new energy on land and soft and direct access of offshore wind power,aims to access a variety of transient overvoltages caused by grid faults or switching operations in large power grid systems,reviews the mechanism re-search,suppression methods and overvoltage assessment methods,etc.It is pointed out that the reactive power imbalance of the access system is the main cause of transient overvoltage in the transient process,and the suppression measures mainly include the configuration of reactive power compensation devices such as adjusting cameras and the optimization of the control strategy of the access system.However,the research on the transient overvoltage mechanism of complex fault types and the overvoltage suppression scheme coordinated by the source network still need to be further studied.Finally,the evaluation meth-ods of transient overvoltage of access system are summarized,and the evaluation requirements of multi-constraint and multi-decision variable combination are proposed.

输电线路杆塔冲击接地阻抗作为影响输电线路耐雷水平的重要因素,在杆塔的接地设计以及状态评估方面应该重点考虑,因此需要提出杆塔冲击接地阻抗控制值.通过建立110 kV、220 kV、500 kV的输电线路模型,计算了不同冲击接地阻抗情况下输电线路的耐雷水平,并基于我国对各电压等级输电线路雷击跳闸率的要求,计算得到各电压等级输电线路杆塔冲击接地阻抗控制值,可为输电线路杆塔的运行维护和状态评估提供参考.同时计算了典型方框带射线杆塔接地体在不同土壤电阻率下满足冲击接地阻抗控制值的最小射线长度,避免了仅凭经验估算造成的施工材料浪费,为实际工程建设提供了参考数据.

In this work, some factors affecting the characteristic parameters of gas-insulated transmission line (GIL) grounding system are studied. Firstly, the model of the GIL grounding system is established. And based primarily on this model, the electrical characteristic parameters are calculated and analyzed. And then, the influences of sensitive structural factors such as the uniformity of the arrangement of the terminal grounding grid, concrete reinforcement, and the span distance of the copper row grounding trunk on grounding system electrical characteristics parameters are studied, and the influence law of sensitive factors on GIL grounding system is obtained. It is concluded that in the design stage of the GIL grounding system, priority should be given to the connection between the two grounding copper bars on the side of the wall and the connection between the concrete structural reinforcement with grounding copper bars. The terminal grounding grid with a non-uniform layout is recommended. The suitable jumper distance of grounding copper bars should be 50m-100m, and the grounding copper bars are connected with concrete reinforcement every 80m-120m is suggested.

When attempting to detect faults in grounding grids, the electromagnetic induction method is hampered by the failure of fault diagnosis based on magnetic flux density detection. An electromagnetic induction impedance method is proposed to diagnose corrosion faults by detecting the induced impedance. A non-destructive testing prototype was developed. The sensor of the prototype consists of biaxial sensing coils, a frequency selection module, and a dual-channel synchronous demodulator. The biaxial sensing coils are configured as four identical coils forming a cross. This symmetrical structure realizes the detection of unknown topological structures in grounding grids. The frequency selection module improves the signal-to-noise ratio of the system. The digital demodulator synchronously extracts the phase information in two orthogonal directions. The key technical indicators of the prototype, such as the frequency characteristics, the amplitude accuracy, the phase accuracy, the interference resistance, and the amplitude consistency between channels are tested. Experiments were carried out on a real-size physical model, corroded samples, and an actual operating substation. The results confirm the feasibility of the method and the prototype for the detection of topological structures, disconnections, and faults in grounding grids.

基于感应视磁阻抗法研制出能分辨接地网拓扑结构以及检测断点和腐蚀点的检测系统,并针对检测系统进行仿真计算和模拟接地网现场试验.结果表明:通过仿真结果和试验数据可以分辨出接地网的拓扑结构,以及断点和腐蚀点的故障诊断,验证了检测系统的可靠性和准确性.

由于采用管道密封绝缘输电,GIL系统受地形、天气和外界环境干扰较小,采用架空线—GIL混合系统输电会变得越来越普遍.当混合系统短路故障时,其电流分布将异于正常输电线路.为了明晰混合系统短路电流分流问题,文中首先建立了架空线—GIL混合输电系统模型,通过开关闭合操作模拟设置输电侧导线发生接地短路故障,GIL管廊内三相导线电流的增强倍数在1.01～2.08倍之间,且当发生三相接地短路故障时的电流增强倍数最高;设置GIL管廊内部导线发生接地短路故障,GIL管廊内三相导线电流的增强倍数在1.05～21.58倍之间,同样,当发生三相接地短路故障时的电流增强倍数最高,为GIL输电系统的安全性设计提供了技术支撑.

为了掌握气体绝缘金属封闭输电线路(gas insulated transmission line,GIL)管廊接地系统的环流特性以及环流特性的影响因素,对GIL管廊系统进行了理论性仿真研究.建立500 kV GIL接地系统和壳体环流模型,分析了环流系统的自阻抗、相间互感等参数,计算得到GIL三相导线外壳的环流值约为导线电流的75％;对比ATP-EMTP程序的解耦模型和MATLAB程序计算的不解耦模型计算结果,验证了计算结果的可靠性.对GIL管廊沿线外壳电位规律进行分析研究,外壳电位呈现出中间低、端部高的U字形分布,人在管廊内部的接触电压符合规程要求.最后,分析相间短接排对环流特性和外壳电位的影响,发现短接排的增加会使端部的入地电流减小,同时也会使外壳感应电压降低,理论研究建议每隔80 m在铝合金外壳上加装短接排.

在接地网无损探测的工程实际中,复杂强干扰会给数据采集带来困难.锁相放大技术能有效从强背景干扰下稳定地提取出微弱的可用信号,在分析变电站测量环境噪声成分的基础上,基于锁相放大器原理,运用虚拟仪器技术设计一种虚拟数字锁相放大器.该锁相放大器利用数据采集卡内部的可编程滤波器进行抗混叠处理,同时对两路传感器输出信号进行采集,利用虚拟信号发生器产生精确的两路0°和90°参考信号,再用数字低通滤波器得到信号的实部和虚部,最后利用成像算法得到接地网的结构图.通过实验室内测试,该锁相放大器具有较高的频率稳定性、幅值和相位测量精度及较强的抗干扰能力.将该锁相放大器用于接地网无损探测系统,在实际变电站得到工程应用.结果表明:该无损探测系统能够应对变电站复杂的电磁环境,可在现场正常工作,并准确探测到接地网结构.

类似于输电线路接地系统,气体绝缘金属封闭输电线路(gas insulated transmission line,GIL)的接地系统对该输电方式的稳定可靠运行至关重要.针对GIL综合管廊接地系统进行研究,首先建立GIL综合管廊接地系统模型,对接地系统的接地电阻、跨步电压、接触电压以及地电位升等电气特性参量进行计算分析,然后研究混凝土结构钢筋、终端接地网布置均匀度、铜排接地干线跨接距离以及主结构钢筋与铜排接地干线跨接距离等敏感结构因素对接地系统电气特性参量的影响,获取敏感因素对接地系统的影响规律,从而得出GIL接地系统设计阶段需优先考虑混凝土结构钢筋与铜排接地干线相连作为自然接地体,铜排接地干线跨接距离相对之下是影响最小的因素.从电气模型角度提出合理的接地系统设计,为GIL综合管廊的建设和运维提供了基础.

在利用电磁感应法探测变电站接地网拓扑结构的工程实际中,复杂强干扰的变电站电磁环境给微弱电磁信号的提取带来困难.针对这一问题,提出一种抗干扰措施,首先利用谐振放大技术和可编程窄带滤波器构成选频放大电路,其次采用陷波器抑制工频干扰,然后基于虚拟锁相放大技术进行信号频谱搬移,以避开干扰的主要频段,所提取的信号为地表感应磁场的矢量.基于此,设计并开发了一套变电站接地网拓扑结构无损探测系统,并在搭建的物理模型和实际小型接地网中进行了测试,验证了系统的可行性和可靠性.

Gas insulated transmission line (GIL) is an advanced power transmission mode. Since the extension of this kind of equipment is relatively long, the grounding design and layout of the GIL will have a direct impact on personal safety and the stability operation of equipment, which should be given full attention. In order to ensure the safe and stable operation of GIL, it needs reasonably design and arrangement of the integrated grounding system in the GIL pipelines. This study designed corresponding grounding scheme for the integrated grounding system of underground GIL pipelines combined with a 550 kV/4000 A GIL. The corresponding simulation model of the integrated grounding system was established with specific parameters of the GIL. The calculation results show that the grounding resistance of the integrated grounding system is 0.217 Ω, which is less than the grounding requirement value of 1 Ω, and it reduces 28.9% compared with the simulation model without considering the natural grounding body. In addition, the step voltage and touch voltage are reduced by 79.91 and 48.97%, respectively. The research results can give some references for the integrated grounding system design of GIL engineering.

在城市高可靠性供电方式下,城市重要用户专门配置的应急电源利用率低下,资源浪费严重.随着未来电网的发展,分布式电源在城市日趋普及,将其兼做应急电源是解决传统应急电源闲置问题、进一步发挥分布式电源作用的有益尝试.提出了一种计及分布式电源的城市重要用户应急电源优化配置方法,以城市分布式电源的类型与特点确定其应急工作方式,利用多人决策AHP方法量化用户重要性,然后基于区域电网结构,以等效重要负荷最大为最优目标,以有功功率平衡为约束,通过遗传算法求解来划分应急孤岛,对进入计划孤岛的重要用户依据允许断电时间进行传统电源配置的容量调整.算例表明,此配置方法能有效利用分布式电源就地应急的能力减少传统备用电源的配置容量,分布式电源利用率受其与重要用户相对位置的影响.

大型海上风电集群的输电系统成本较高,针对输电系统的拓扑优化可以有效提高系统经济性.为了解决输电海缆路径受风电场布局限制可能导致海缆随意穿越风电场区域问题,文章建立了考虑海缆可行路径约束的风电集群输电系统的经济性模型,通过设计蚁群算法对该优化问题进行求解,并从择路策略和信息素更新策略计算方法等方面对传统的蚁群算法进行了改进.以江苏如东海上风电场作为实际工程进行算例分析,结果表明:相比目前工程规划方案,所建模型可以有效提高系统经济性;相比传统蚁群算法,改进蚁群算法的优化效率大大提高.

科学有效的风电场实时有功控制策略能够充分挖掘风电场有功调控的潜力,提高其参与电力系统调度的能力。考虑风电场实时运行状态和超短期功率预测结果,提出了一种基于风电机组调控能力排序的风电场实时有功控制策略。首先选择风电机组的实时出力、预测功率的变化趋势和功率调节速率等统计量作为评估指标,然后运用熵值决策法和模糊理论将风电机组的有功调控能力定量化,再根据风机的实际运行状况和超短期功率预测结果等信息将风电机组分类,最后根据机组分类结果和有功调控能力排序表对风电场内风电机组的有功出力进行调整。以中国北方某座风电场为算例,演示了整个调控步骤。

为了掌握轨道电磁发射中电枢的电流熔蚀特性,对小口径电磁轨道发射装置进行了实验研究。实验装置为20 mm×20 mm,方形口径轨道电磁发射装置,通过控制发射实验中电枢出膛的速度,研究了电流幅值、电枢质量和转角厚度(载流能力)等因素对熔蚀的贡献。另外,基于电流幅值递增实验,总结了熔蚀程度的几种模型和相应的电流幅值范围。结果表明:不同的发射条件对电枢的熔蚀程度影响有所差异;电流分布是熔蚀产生的直接原因,能显著影响熔蚀程度;电枢质量对起始时刻的熔蚀有影响;电枢转角厚度对熔蚀的贡献不大(电枢载流能力足够的情况下);随着电流幅值的增加,电枢表面熔蚀有从电枢中端偏下位置沿棱边向电枢中部和电枢头部延伸的趋势,在此过程中归纳出了3种熔蚀程度及其对应电流范围:轻度熔蚀,对应电流181~293.8 k A;中度熔蚀,对应电流293.8~320.8 k A;极度熔蚀,电流>320.8 k A。