Electric robots are the important technical support for the inspection of power grid security and intelligent operation. However, the harsh environment in the tropics restricts the application of electric robots in substations, transmission lines and other power grid scenarios. First, the main types of electric robots and the characteristics of some typical service environment were analyzed in this paper, and then, the impact of tropical environment on electric robots was studied. Next, relevant national and industrial standards of electric robots were summarized, with focusing on environmental test items, test methods and severity levels of the equipment. Finally, through results obtained by analyzing environmental test standards for robots, relevant conclusions and suggestions were put forward. This would provide references for the stable application of electric robots in tropical regions.
Abstract In order to analyze the transmission characteristics of abnormal discharge current in transmission lines, considering the frequency-dependent characteristics of line parameters, the transmission of abnormal discharge micro-current is studied theoretically and analyzed with examples. Then, ATP-EMTP is used to establish a hidden danger micro-current transmission model for the elevated line, and the micro-current transmission situation is simulated. The influence of frequency and different voltage levels on the hidden danger micro-current transmission characteristics is mainly considered. The results show that the higher the frequency of the initial signal, the larger the equivalent resistance and the smaller the equivalent inductance of the line. The frequency has little effect on capacitance and conductance. The attenuation constant of high-voltage class lines with multiple split wires is greater than that of low voltage class lines with single split wires, and the attenuation constant only increases slightly with the increase of split wires.
Abstract The characteristic of traveling wave transmission has great influence on the location precision of the fault point. In order to accurately evaluate the transmission and attenuation characteristic of actual traveling wave on transmission lines, a typical asymmetric arrangement 110kV transmission line is selected as the research object. First, the parameters of the transmission line are calculated, and the traveling wave decoupling algorithm is derived. Then, the traveling wave current collected by the distributed traveling wave monitoring system on the line is analyzed. The results show that for a short distance asymmetric 110kV line, it can be decoupled by the conventional decoupling balance line method, and the coupling component ratio is less than 2% after decoupling. With the increase of transmission distance, the attenuation degree of traveling wave increases. When the transmission distance is 60km, the attenuation of line mode is 21.2% and the zero mode attenuation is 50.4%.
Abstract Aiming at the problem that large-scale electric vehicles(EVs) access to the distribution network charging will affect the safety and reliability of the power grid, this paper proposes an optimal scheduling method for large-scale access of EVs to the distribution network based on the improved Preference-inspired Coevolutionary Algorithm. First, a large-scale response scheduling model is developed based on EVs as flexible loads. Then, a multi-objective optimization model is established by considering five factors: grid load fluctuation, user cost, environmental governance, user flexible travel time, and charge state. Finally, a multi-scenario comparative analysis is performed with the help of an improved preference-inspired co-evolutionary algorithm, an optimization algorithm. It is verified that the scheduling method can realize the effective management of loads in the region, reduce the management cost of microgrids and the cost of environmental pollution control, and improve the users' flexible travel time and SOC.
China Light and Power Company Ltd. (CLP) is responsible for supplying electricity to the whole of Hong Kong except Hong Kong Island and Lamma Island. In CLP's Castle Peak power plant, 18 kV and 23 kV electric supplies are generated. The voltage is then stepped up to 400 kV for transmission. The intermediate control between those transformers and the major 400 kV overhead transmission system lies with a standard "one and a half breaker configuration" switching substation. The substation houses single phase encapsulated SF/sub 6/ circuit breakers. In the urban centres, 400 kV substations are installed to step down 400 kV to 132 kV or further to 11 kV for distribution. This paper describes the development of an online distributed information system for monitoring the condition of the whole HV transmission system. The system continuously monitors the status of each circuit breaker (CB) together with important operational parameters, such as duration during making and breaking, operations of hydraulic pumps and SF/sub 6/ gas pressure etc. Each group of CBs is monitored by a stand-alone microcontroller which is interconnected with all other microcontrollers using a local area network with a baud rate of 9,600. The information can be recorded on the hard disk of an onsite microcomputer and further transmitted back to a remote computer for alarm generation and multi-station supervision. The CLP 400 kV substation and the Tsz Wan Shan 400 kV substation are amongst the first targets for development.
Large-scale electric vehicle access to the distribution grid for charging can affect the security and economic operation of the grid. In this paper, an optimal scheduling method for large-scale EV access to the distribution grid based on the improved preference-inspired co-evolutionary algorithm using goal vectors (PICEA-g) is proposed. First, a large-scale response scheduling model is developed based on EVs as flexible loads. Then, a multi-objective optimization model is established by considering five factors: grid load fluctuation, user cost, environmental governance, user flexible travel time, and charge state. Finally, multi-scenario simulation analysis is performed to verify the effectiveness of the proposed control strategy and optimization algorithm. The experimental results show that the improved PICEA-g algorithm outperforms the remaining several algorithms when the size of electric vehicles is larger than 50. And based on this method, it realizes the effective management of loads in the region, and reduces the management cost of microgrids and the cost of environmental pollution control, and ithe users' flexible travel time and state of charge.
Lightning is one of the important causes of transmission line tripping. In order to improve the effectiveness of transmission line risk assessment and provide reference for lightning protection design, it is necessary to study the key geographical factors affecting lightning tripping. In this paper, firstly, the geographical features such as altitude, slope, slope aspect, slope position and land type of the tower are extracted by using ArcGIS geographic software, and then the association rules are used to study the relationship between various geographical factors and lightning tripping. Finally, the entropy method is used to calculate the weight of various geographical factors on lightning tripping and determine the key factors. After calculation, the influence weight of slope on lightning tripping is 0.49, which accounts for the largest weight among geographical factors, so the influence of slope on lightning tripping should be considered in lightning protection design.
To address the degradation of grid quality and charging efficiency associated with the large-scale integration of electric vehicles (EVs), a multi-stage balanced flexible load scheduling method is proposed. This approach is designed to facilitate peak shaving and valley filling, balance intermittent energy fluctuations, and provide auxiliary services, thereby significantly altering system load characteristics, smoothing energy fluctuations, reducing operational costs, and enhancing the regulatory capabilities of power grid dispatching operations. A multi-objective optimization mathematical model is developed, focusing on key indicators that impact the scheduling process, including network loss, operational cost, and user satisfaction. A multi-stage flexible load scheduling framework is introduced within the competitive swarm optimization (CSO) algorithm, resulting in the design of an advanced CSO algorithm. This algorithm is distinguished from traditional methods by the implementation of advanced learning based on grouping after a random competitive learning phase, which enhances the efficiency of particle swarm learning while ensuring stable population convergence throughout the optimization process. Furthermore, the CSO framework is maintained to ensure effective population diversity, greatly improving the optimization performance. Simulation results indicate that the voltage fluctuation index of the proposed algorithm is 1.8% lower than that of the standard CSO algorithm, while network loss and operational costs are reduced by 2.83 and 5.81%, respectively, thereby validating the effectiveness and efficiency of the proposed approach.
Lightning parameters are indispensable key parameters in lightning protection design. Based on the ground lightning data from the Hainan lightning location system in 2009, the relationships between lightning parameters (the average lightning current amplitude of total ground flashover, the proportion of positive and the negative flashover, and total ground flashover density) and terrain curved-surface parameters (slope, slope aspect, and slope position) are studied by means of GIS spatial analysis and mathematical statistics. Firstly, it is concluded that there is a cubic function relationship between the average lightning current amplitude of total ground flashover and slope. The proportion of positive flashover decreases with the increase of slope, and the distribution of total ground flashover density features U-shape with the increase of slope. The lightning protection should be strengthened for the transmission lines built on the mountain with the slope below 10° or above 48°. In addition, when the slope aspect is in the southwest direction, the average lightning current amplitude of total ground flashover and total ground flashover density are the lowest, while the proportion of positive flashover is the largest among all slope aspects. So some anti-backflashover measures should be taken for transmission lines built in the southwest slope aspect. Besides, the average lightning current amplitudes of total ground flashover are the largest and the total ground flashover densities are the highest in ridge and valley among all slope position. Some special lightning protection measures should be considered to be taken in ridge and valley.
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