At present, passive noise reduction measures such as improving the process mechanism of the equipment body and setting muffler on the noise propagation path are mainly adopted for transformer noise reduction. However, the noise reduction facilities derived from this method have limited noise reduction effect, and there is no experience in the study of noise distribution of transformer itself. In order to solve the noise reduction problem from the source, this paper uses active noise reduction method to explore the noise reduction effect of transformer. The three-dimensional structure simulation model of transformer is established, the amplitude distribution of surface vibration is calculated, and the sound pressure level distribution of transformer at different distances from the outer wall in normal operation is obtained. Under the condition that the real transformeris loaded with a single excitation source, the vibration and noise distribution characteristics of the transformer surface before and after the damping and noise reduction module is used are obtained. The results show that the effect of vibration and noise reduction is obvious after active noise reduction measures are adopted.

AbstractThe power frequency electric field is the most important electromagnetic environmental factor in alternating current power transmission projects. The humidity has a negative influence on available electric field measuring devices, which may lead to discrepancies of up to seven times the actual value at a relative humidity exceeding 80%. The changes in the support and probe shell impedance may be the reason for the error. The optimization measures include modifying the communication mode, designing a suitable structure and circuit for the probe, and using composite insulating material with strong hydrophobicity for the support. A three‐axis omnidirectional electric field measuring device was developed based on wireless communication and composite support. The variation of the measured electric field strength value is less than 1% at relative humidities ranging from 45% to 90% in the laboratory, and the measured results obtained in high humidity at the high‐voltage test site and under the transmission line demonstrated high accuracy. The research demonstrates that the composite support can be used to improve the performance of conventional devices. The proposed device can better meet the needs for accurate measurement of electric field strength in a high‐humidity environment and overcome the technical problems raised by the IEC standard.

为消除电晕放电造成的能量损耗和电磁干扰,对不同种类金具的电晕特性以及不同电压等级下金具选型进行研究.利用紫外成像仪对几座超高压交流变电站的电晕放电现象进行观测,找出易发生电晕放电的金具;对此金具结构建立三维有限元仿真模型,计算在施加500 kV和750 kV电压等级下,不同尺寸金具表面电场强度分布情况,并针对场强较大的结构进行优化设计.研究结果表明,随着均压环、屏蔽环管径和屏蔽球球径的增大,其表面电场强度逐渐减小;结合金具表面起晕场强控制限值,给出了500 kV和750 kV电压等级下,耐张绝缘子串屏蔽环、V型绝缘子串均压环以及导线屏蔽球的尺寸选型.

The measurement accuracy of the synthetic electric field of high-voltage DC lines has an important influence on the electromagnetic environment assessment, which is directly related to the environmental protection acceptance of related projects. At present, the most commonly used synthetic field measuring equipment is the rotating field mill tester, whose sensor adopts the structure of rapidly rotating rotor and the mode of carbon brush contacting and grounding. The intermittent contact during high-speed rotation makes the carbon brush grounding unreliable, and the ion accumulation on the rotor leads to the change of electric field and ion current distribution near the measuring point, thus making the measurement results quite different from the actual electric field. In order to solve the inherent defects of the existing grounding mode and rotating structure, based on the measuring principle and structural arrangement of field mill, this paper designs a horizontal reciprocating synthetic field measuring anti-wear vibration sensing mechanism, puts forward the size and arrangement of shielding and induction plates, deduces the sinusoidal relationship between the synthetic electric field and the induced current, draws the modulation waveform of the induced signal, analyzes the amplitude and phase relationship between the synthetic field and the ion flow field, and determines the rotating speed of the rotating motor to be 4 800 r/min and frequency 80 Hz through the limit value of wind speed measurement condition. The results show that the stator plate grounding of the horizontal vibration structure eliminates the accumulation and distortion of ion current; the connection of micro ball guide sleeve can effectively reduce mechanical wear; and the sensor has good linearity, which can meet the requirements of field measurement.

In order to eliminate the energy loss and electromagnetic interference caused by corona discharge, the size selection and design of fittings under different voltage levels and different altitudes are studied in this paper. The corona discharge phenomena of several extra high voltage (EHV) alternating current (AC) substations are observed by ultraviolet (UV) imager. It is found that the areas with serious corona discharge in EHV AC substations are mainly concentrated on the shielding ring of terminal insulator string and shielding ball of conductor. The electric field calculation model is established for two typical fittings with serious corona discharge in COMSOL multiphysics software, and the distribution of electric field intensity on the surface of different sizes of fittings under the voltage level of 500 kV and 750 kV is calculated based on the finite element method. The results show that the maximum electric field intensity (MEFI) on the surface of the shielding ring of the terminal insulator string appears at the connection between the arc and the straight line of the shielding ring; the MEFI on the surface of the shielding ball appears in the ball head. Compare the numerical values of the corona onset field intensity (COFI) of the fittings at different sizes and altitudes calculated by using the physical calculation model of the COFI, so as to determine the size selection of the fittings at different altitudes and different voltage levels. The corona onset tests of fittings carried out in low altitude areas and high altitude areas verify the applicability of the size selection design of fittings at different altitudes and different voltage levels. The results show that the size selection design of fittings for 500 kV high altitude substation shall refer to the size selection of fittings for 750 kV plain substation.

The radio interference generation mechanism of AC-DC parallel transmission lines is different from that of conventional lines, so that the prediction model is either too rough and leads to large errors, or too complicated to be mastered by engineers. In order to take into account the accuracy of radio interference solution and engineering practicability, an error back-propagation feedforward neural network model combined with gray correlation theory is proposed. First, the gray theory screening of multiple impact indicators of radio interference, and then the indicators that have a real impact on radio interference as input variables, the BP neural network fitting algorithm is used to predict the radio interference. Validation combined with the actual measured radio interference samples of the AC-DC parallel transmission lines that have been put into operation, the results show that compared with the traditional algorithm, the prediction accuracy of the BP neural network prediction model is improved by 14.6%.

Corona discharge on the surface of power transmission and transformation fittings becomes increasingly serious with increasing voltage levels, especially for many grading rings in transformer substations. With the enhancement of people’s environmental awareness, the environmental protection administration requires noise and electromagnetic environment at transformer substations shall meet relevant standards. In order to suppress corona discharge on the surface of a grading ring, it is necessary to study its corona onset characteristics. Considering the basic physical process of the corona discharge, in this study, the electric field intensity is first calculated at any point in the space around the grading ring through ring charge simulation. Then, based on the theory of secondary electron emission, criteria for calculating the onset voltage of negative corona of the grading ring are derived, leading to an area factor of a photon absorption function suitable for the grading ring. In this way, a three-dimensional (3D) calculation physical model of the corona onset suitable for the grading ring is developed. This study calculates the corona onset voltage and field intensity of the grading ring under the typical working conditions by using the proposed 3D calculation physical model of the corona onset. The calculation results are compared with test results of the corona onset voltage and field intensity of grading rings in an outdoor 750 kV transformer substation in an ultrahigh voltage (UHV) alternating current (AC) test base. Furthermore, the simulation results of the area factor of the photon absorption function, electron collision coefficient, electron adsorption coefficient, and effective ionization coefficient in the 3D calculation physical model are obtained. In this way, the accuracy of the 3D calculation physical model of the corona onset proposed in this paper is verified. The research results can provide a theoretical basis for the corona prevention design of grading rings in extra high voltage/UHV AC power transmission and transformation projects.

由于线路间耦合效应,交直流并行线路产生的无线电干扰与单独线路不同.为研究交直流并行输电线路无线电干扰与温湿度的相关性,建立了无线电干扰与气象自动化同步测量系统,开展了长达1年的监测.由于数据量巨大且存在随机误差,采用了Pauta准则进行离群值处理,并通过计算处理后的数据,分析了无线电干扰与温湿度之间的相关性.结果 表明,好天气条件下,交直流并行输电线路无线电干扰大体上与温度呈微弱的正相关性,与湿度呈较强的负相关性.通过组合单点数据的分析结果,得到不同季节好天气条件下交直流并行输电线路无线电干扰的横向分布规律,为并行线路无线电干扰的分析提供了支撑.

随着电网的不断建设,交直流输电线路同走廊并行架设已在多处出现.目前,交直流混合电磁环境监测多以单点离散测量为主,无法实现横向分布的连续实时测量.通过建立工频电场、无线电干扰、合成电场等测量设备沿同一路径的分布式实时数据采集系统,实现交直流并行线路电磁环境移动式横向分布测量及数据的动态管理,并以典型合成电场数据为例,研究了垂直于线路走廊155 m的横向断面合成电场分布趋势.结果 表明,实测数据与仿真计算结果趋势较吻合,为交直流并行线路合成电场研究提供了参考.

The UHV transmission lines usually have large regional spans and involve various weather conditions, which will have different effects on the circuit design and electromagnetic environment. However, the existing research lacks the ion flow field analysis of AC and DC parallel lines under different weather conditions. Hence, we studied the distribution law of the ion flow field of ±800 kV DC and 500 kV AC parallel transmission lines under different weather conditions, and compared the calculated results with measured results. First, we used the meshless method to model the ion flow field of AC and DC parallel lines in different weathers. Then, the influence of environmental factors on the ion flow field was analyzed. The effects of temperature, humidity and haze on the distribution of the ion flow field were obtained based on long-term monitoring and measurement. Results show that the ion flow field of the theoretical calculation results was basically in accord with the actual measurement. The ion flow field of parallel lines increases with the rise of temperature, first increases and then decreases with the rise of humidity, and increases with the rise of haze.

目前,国内外对于交直流并行输电线路无线电干扰的特性研究还处于起步阶段.通过分析现有的单独线路无线电干扰测量模式的弊端,建立了基于气象参数与无线电干扰实时同步测量系统,并基于DBSCAN算法对一年的无线电干扰数据进行数据处理和分析.为了分析无线电干扰与温度之间的相关性,选取直流区域、交直流过渡区域和交流区域典型点位数据,按温度分段分析,得到了各个区间段内无线电干扰与温度之间的关系,为后续的交直流并行输电线路无线电干扰分析奠定了基础.

In order to reduce the electrostatic induction effect of hybrid electric field generated by the UHV AC/DC parallel lines on residential houses and metal supports near the transmission corridor, this paper put up shielding wires paralleled to the AC/DC lines on the platform of residential buildings in the parallel to the AC/ DC lines were established, and measured Distributions of the power frequency electric field and DC ionized field in parallel line direction were measured respectively, and the impacts of wires’ height and number on the shielding effect on the hybrid electric field were also analyzed. And then built grape trellis metal support models for grape growing parallel to the AC/DC lines were set up, and the induced voltage distributions with different grid structures were measured. The results show that the shielding wires can effectively improve the spatial mixed electric ionized field under transmission lines can be effectively reduced by the shielding wires, and that has exist the best shielding structure of the wires also exists. The induced voltage of the metal support was greatly influenced by the support, and the maximum voltage value had no tingling sensation to the human body.

提出一种基于无网格径向点插值法的混合离子流场求解算法,实现了对交直流并行线路离子流场的精确求解.利用多项式的径向点插值法对传统无网格法的形函数进行修改,使形函数在待施加边界约束条件的点处满足Kronecker-δ函数性质,以符合直接施加边界约束条件的要求;再结合交流线路对混合离子流场的影响因素,得到混合离子流场和离子流密度值;最后,以500 kV博塔线和±800 kV天中线在武陟段的并行线路为例进行仿真计算与实验测量分析.结果表明,采用所提算法可将离子流密度的相对误差缩减至4.5％,将离子流场的相对误差缩减至24％.

调查湖州地区德清县鸟害区域分布和时间分布规律,提出鸟巢、鸟粪等电网灾害的机理,在此基础上,提出配电线路鸟害防治方法.结果表明,鸟类筑巢呈逐年饱和上升趋势,主要分布在湿地环境区域;鸟害主要发生在春季及晨昏时期,与鸟类繁衍、栖息、觅食等行为相关;采用驱鸟、线路绝缘化改造等防鸟措施,防治效果良好.

Electric field measurement is widely used in electric power, aerospace, medical and other industries. In recent years, with the gradual expansion of the coverage of ultra-high voltage power grids nationwide, the debate about electromagnetic environment brought about by high-voltage power equipment is increasing. The electromagnetic environment pollution problem of UHV transmission and transformation lines has aroused widespread public concern. The research on the electromagnetic environment of high-voltage transmission systems is rapidly emerging in China.

In this paper, fine-grained classification is applied to get animal population for evaluate electromagnetic environment effect of transmission line on ecosystem in Tibet Plateau. Spectrum features of bird songs and photography of bird image have be for the specific characteristics with significance in classification by Fine-grained classification (FGC), which is used to get animal population, and then bird population growth or not is direct index for the electromagnetic environment effect evaluation. Using the method, the number of cranes is increasing year by year near the converter station, which indicates effect is less likely.

Multi-terminal HVDC transmission technology using voltage source converters is suitable for integrating large off-shore wind farms. DC voltage stability is the main problem for coordinated control of Voltage Source Converter based Multi-Terminal High Voltage Direct Current (VSC-MTDC) transmission system. The fixed droop coefficient of the traditional droop control leads to poor flexibility under severe disturbance. On this basis, this paper proposes an adaptive droop control method. By detecting the DC voltage deviation and the power margin, the fuzzy logic control is intended to adjust droop coefficient adaptively. Simulation results in PSCAD/EMTDC show that the proposed adaptive droop control strategy can reduce DC voltage deviation caused by the transmission power change and improve system operating performance within the allowable power margin range.

To save land resources, the construction of the high-voltage direct current (HVDC) and high-voltage alternating current (HVAC) hybrid transmission lines in the same corridor is inevitable. To provide suggestions for the construction of the AC/DC parallel lines, the hybrid ionized field of AC/DC transmission lines was calculated by the meshless local Petorv–Galerkin (MLPG) method for the first time. In this method, the radius of local sub-domain is adjusted to the nodes close to the global boundary, but not exactly on the boundary. It can avoid the boundary integral, as well as having simplified calculation. The method was validated by comparing with measured results and calculation results. The MLPG method is beneficial to obtaining high-precision results by constructing the more complex shape function. Finally, a field distribution of the parallel line of about ±800 kV DC/500 kV AC was calculated. Moreover, the influence of different parallel spacing and AC voltage level on the hybrid ionized field was analyzed, which provides theoretical basis for real parallel lines design.

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.

为了合理选取适用于江苏如东大规模集群式风电工程的并网方案,首先分析比较了基于交流输电方式和柔性直流输电方式的海上风电并网技术的优缺点.然后给出了基于柔性直流输电方式的海上风电场并网的几种典型拓扑,并对各种并网拓扑的优缺点进行分析.在此基础上,对规划建设中的江苏如东大规模集群式风电工程的并网拓扑展开研究,提出了全交流、交流和直流点对点、交流和直流环形、交流和直流星形4种典型的并网方案.最后,选择经济性比较范围,采用现金流折现模型,从设备成本、维护成本和损耗费用3个方面计算了所提方案的总成本,进行了经济性比较和分析.结果表明,该工程采用全交流方式时经济性最佳,其次分别为交流和直流点对点混合并网方式、交流和直流星形混合并网方式、交流和直流环形并网方式.