Search

Whether the structure design of transmission line poles and towers is reasonable or not has a great impact on the construction cost of the whole power supply system. In this paper, the type selection design and structure optimization of 66 kV transmission line poles and towers are studied as the main content. Firstly, the data of pole and tower type selection and double circuit tower type of 66kV transmission line are given. Secondly, the selection of insulators and the optimization design of tower head clearance are carried out. Finally, the optimization design of pole and tower structure is carried out based on finite element method. The research results of this paper can provide a reference for the type selection design and structure optimization research of 66kV transmission line poles and towers.

In the mountainous transmission lines, in order to respond to the national and national grid requirements for environmental protection, the design institute needs to design the towers for the long and short legs and the foundation of the tower. To this end, the paper gives the design scheme of the long and short leg iron tower in Liaoning area, and analyzes the design conditions of the iron tower, the base surface measurement of the iron tower, the insulation coordination and the optimization design of the tower. The purpose of this paper is to find the mutual configuration of the long and short leg towers and the high and low foundations that can be used to optimize the transmission line in mountainous projects, and use finite element software to verify that the minimum amount of base materials is the same when the tower position is constant. The basic base surface has the least amount of shovel excavation, which can better protect the geographical environment of the area where the tower is located, and can also control the amount of basic materials to a certain extent and reduce the total investment of the project.

Wind farm operation is characterized by large scale, fast and disorderly, the construction of grid structure is not complete, the fast adjustment of power supply in the power grid does not match to others, the objective laws of electric power system and uncontrollable and intermittent of wind power, and adjustable power supply capacity constraints in power grid, all of them cause the consumptive ability of wind power grid, which leads to more and more abandoned wind. This paper studies the tower neural network method, according to different height wind speed and wind direction data of historical wind tower measuring, combining with the fan power of historical observation data of wind farm, and building the neural network model, then the sample data will be input to the neural network model which has built to get theoretical power fan and abandoned wind power. By comparing the wind tower method, neural network method, model machine method with area integral method calculate abandoned wind power data, evaluate the effect that based on abandoned wind power tower evaluation model of neural network method in low wind speed has a good reference value, relatively close to the measured wind speed.

Traditional power distributed network is transformed from single power supply radial network to more than one power supply loop network, direction of the power flow is changed, Therefore action of right protection cannot be completed in the micro-grid operating in the grid-connecting mode and two kinds of operation mode switching of interconnection and lonely island. The four standard of distribution system protection namely, selectivity, reliability, sensitivity and quick action cannot be effectively meet. In paper, influence on relay protection of the micro-grid is expounded in order to solve the problem of micro power grid relay protection, according to the load sensitivity of feeder circuit, current differential protection module and inverse time over-current protection module are established, the parallel operation protection strategy is designed, the simulation results with the typical micro-grid show that performance of the proposed protection module is more rationality and effectiveness.

Wind power prediction accuracy is important for assessing the security and economy when wind power is connected to the grid, and wind speed is the key factor. This article presents a future four hours prediction scheme that combined chaos phase space reconstruction with NWP method. Historical wind speed data are reconstructed as phase space vectors, which are used as the first input part of prediction model, and the NWP data at the prediction time as the second input part. Wind speed at the height of turbine hub is derived from neural network model output. To test the approach, the data from a wind farm are used for this study. The prediction results are presented and compared separately to the chaos neural network model, NWP ANN model and persistence model. The results show that the method presented in this paper has higher prediction precision.

For direct drive synchronous wind power generation system, the converter of direct drive motor is connected to the stator side of permanent magnet synchronous generator side, through controlling the converter, the maximum wind energy can be captured. Main circuit design of the direct-drive grid-converter is studied. Firstly, power grid side filter is designed and calculated, LCL filter is used instead of traditional L type filter, in this way, the value of the inductance、 the volume and cost are reduced effectively, and its inhibitory effect on high frequency signal is more obvious. Not only meet the vector triangle, but also grid connection harmonic current is restrained. Secondly, the filter of motor side is also designed, about the problem of voltage reflection for long cable drive motor PWM converter on the motor side, the solution is to reduce the output value of the du/dt and increase the pulse rise time, at the same time the reflected voltage of the motor side is also reduced. Finally ,Brake unit is researched, at the instant of the power grid voltage dips is detected, chopper control is started to IGBT of brake unit, making the machine side power in addition to the net from the side of the part, the rest are consumed in the brake unit, to ensure that the equipment can grid-connected operated. The last but one, the pre-charging circuit is included.

In this paper, the data of information in intelligent substation are classified, information flow in communication network is analyzed, based on IEC61850 standards, and there are four categories: control and protection unit, the centralized fault recording unit, the monitoring and five-prevention unit and the measuring, in the application systems of substation. And then, the information integration scheme applied to intelligent substation is proposed. The plan completes the information collect, processing, upload and display, and other functions, realizes real-time communication efficiently between each layer in the internal substation, and between substations and higher control center, based on the unified modeling of all objects within the substation, building information integrated platform in the station level. Information integration platform can not only ensure authenticity, integrity and consistency within the substation information data, but also maximize the information sharing and interoperability of the equipment among application systems in the substation.

In this paper, the safety index of distribution system containing distributed generation is discussed,Based on the research of the power distribution system. According to the practical situation, distribution system containing distributed generation such as the wind power generation unit is considered as a random power,and introduced the concept of “Island formation probability”. Research and analysis of the safety evaluation index of the distribution systems containing distributed generation, from the two aspects of system failure probability and failure consequence. And through the actual example verifies that this set of safety evaluation index of practicality. The set of indicators to characterize the security level of grid connected wind power system for different regions of the network or the same area of the different planning schemes, all has important guiding significance.

This paper presents a centralized reactive control scheme of grid-connected inverter of distributed generation system. The power electronics interface performs the optimal operation to extract the maximum active power, while it also plays a key role in reactive compensation systems. A reactive power optimization algorithm including DG sources based on genetic algorithm is proposed. The corresponding particular model is built which takes into the minimum network loss and node voltage constraint. Genetic algorithm is used in reactive power optimization. The simulation examples show that the validity and effectiveness of the proposed algorithm in reducing network losses and improving the voltage profiles.

In this paper,based on the characteristics of transformer inrush current waveform analysis of the protection of its reliability and its high-pressure differential between trial. Together with a large transformer (voltage rating of 500kV) of the differential protection analysis of actual cases, their first-hand data and field research and analysis of test waveforms and found that in order to avoid inrush current caused the error transformer differential protection movement, on-site technical staff conducting differential protection setting process, notonly the parameters used, the data comply with the relevant rules and standards, Shu Xi differential protection features, but also must understand the high-pressure test on the transformer inrush current characteristics effects, and even more fully to play the modern computer equipment recorded the role of wave devices to increase as much as possible the actual effect of transformer differential protection.

Now many kinds of technologies applied to wind-power generation are in the ascendant, among which the technology of variable speed and constant frequency (VSCF) is getting increasing recognition for its characteristic of high-efficiency and practicability. In this paper, it brought forward the method of emulating wind turbine by squirrel-cage induction motor to solve the prime motor issue for the study of wind power generating system in lab. The reliable and integrated laboratory experimental platform of wind power generation system was constructed in this paper. The result of the experiments all validated the validity and feasibility of the model of VSCF wind power generation system platform in the lab.