Using battery energy storage system (BESS) to smooth wind power volatility can improve the stability of wind power output. According to the intermittence and volatility of wind power output, a smoothing control strategy by using moving average algorithm for wind power was proposed, which took the state of charge (SOC) in energy storage system and wind power volatility rates into account. It was compared with the traditional first-order low-pass method for smoothing wind power output. The effectiveness of the proposed control strategy was verified with the MATLAB/SIMULINK simulation, whose results have shown that it can smooth the wind power output, and can effectively decrease the battery energy usage and storage energy.
Wind power prediction is significantly important to the safe and economic operation of power system with large-scale wind power. The effect of the characteristic of wind speed and wind power, the algorithm and input variables of prediction model on power prediction error was analyzed. Taking the measured data in a wind farm as an example, the error evaluation indices were used to evaluate the predictive results, and the method of model modification to gradually reduce the prediction error of wind power has been proposed. Then, the flow chart of prediction error modification was presented. The method can improve the prediction accuracy of wind power, and make the wind power prediction system better for the practical production.
As one of the most important parts of smart grid, smart substation is the "key node" of information interaction of six links in smart grid as well. The substation information network, the trunk communication network between smart substation and the terminal of regulation, operation and maintenance, as well as the terminal communication network between smart substation and power distribution and consumption were systematically studied. Then, the simplified technology route of substation information structure and the development scheme of the trunk and terminal communication network framework were presented. The research results can provide important theoretical supports and practical basis for the research and development of the new generation smart substation, and also provide important guidance for the design and construction of demonstration projects in the next step.
A strong smart grid requires relay protection not only to improve its performance, but enhance the optimization and coordination with stability control system as well. A new concept of hierarchical protection & control system oriented to regional grid security and stability was proposed. On the basis of conventional protection configuration, the substation-area protection & control unit and wide-area protection & control unit based on information sharing were set up. Then, the framework and function deployment of hierarchical protection & control system, as well as its application examples were introduced. Through the comparison with the existed protection scheme and wide-area protection scheme, its performance was also analyzed. The results have shown that the proposed hierarchical protection & control system can be promoted and applied in smart substation construction as application scheme.
With the continuous advancement and deepening of smart substation construction in State Grid Corporation, according to the guidance of new generation smart substation with "highly integrated system, rational layout, advanced and applicable equipments, energy conservation and environmental protection, and supporting integrated control," the technology of equipment integration and layout optimization was studied, combined with the feature of Dashi 220 kV new generation smart substation. Then, the design principles of primary and secondary equipments of smart substations were explicitly stated, the scheme of equipment selection among disconnecting circuit breaker, gas insulated switchgear, gas insulated busbar, hierarchical protection & control system and container-type equipment was proposed. Finally, the main wiring diagram and optimization design of general layout were presented for Dashi substation, and technological and economic analysis was carried out on the highly integrated equipments in smart substation, which would provide references for similar substation design in future.
Based on the constraint conditions of type, capacity, location of existing distribution generation (DG) in the planning area and substation load-bearing capacity, a comprehensive optimal planning model for substation with load demand satisfied, by considering DG and different block geographic information factors (GIF), the construction cost of distributed substation, the cost of feeder and operation cost including current supply losses, as well as the influence of GIF like land properties on the location and cost of construction. Furthermore, the influencial factors of different block geographic information on construction cost were obtained by means of interval analytical hierarchy process. Finally, optimization was carried out on the planning model by using quantum-behaved particle swarm optimization (QPSO) algorithm, and the proposed model and algorithm were proved to be scientific and effective through the empirical study on a planning area.
On the basis of national UHV power grid planning and Zhejiang power grid planning, the power supply area, planning location and rationality of UHV AC/DC stations were analyzed, and an adjustment and optimization scheme for Zhejiang main grid by locating at Zhezhong and Ningdong was proposed, combined with the basic situation of power consumption forecast and power balance in Zhejiang Province. Finally, the technical and economic comparison and analysis were carried out on the different location schemes of Zhejiang UHV AC/DC hybrid systems.
In order to better understand the wind load calculation in the transmission line design, the calculation formulas of wind load and the setting of calculation parameters were compared among four different design standards: Technical Code for Designing 110~750 kV Overhead Transmission Line (GB 50545—2010) in China, IEC 60826—2003, ASCE 74—2009 and JEC 127—1979. Moreover, based on the calculation and comparison of wind load in a real 500 kV project, the differences among the calculation results of different standards were analyzed under the same design condition. The results show that the wind load defined in the China’s code is little numerical different from those calculated by other codes, however, some parameters are still worthy of further discussion.
With the development of society, the audible noise in substation has been paid more and more attention, so it is necessary to study the substation’s audible noise. Firstly, the noise of 110 kV Heshangshan Substation in Chongqing was measured with sound level meter, and the audible noise in substation was predicted by using GM(1,1) model, with which the monthly variation of the noise can be obtained. Then, the noise in different temperatures and distances was predicted by using radical basis function (RBF) neural network. Finally, the audible noise in different temperatures and operation loads of transformer was calculated with using RBF neural network, which could provide references for the design of new substations.
Transmission line corridor has become a prominent problem that restricts power grid construction. In the economically developed regions, vertically arranged F-type tower could be applied to reduce the corridor occupied and the difficulty of project construction. F-type tower had a successful application in the Three Gorges-Shanghai ± 500 kV transmission line project, but it was firstly used for UHV transmission line. Because of higher voltage level and larger transmission capacity, the electromagnetic environment, conductor section, and tower loads are greatly different from those in original design. Through the monographic study of UHVDC transmission lines with vertically arrangement, the basic principles of the conductor arrangement type, conductor’s minimum distance from ground, and corridor width of the F-type tower with vertical arrangement were determined, and the optimization scheme was proposed combined with the actual issues in the project.
With the rapid development of energy storage technology, the large-scale energy storage system has gradually become a key method to ensure power system reliability and safety, of which electrochemical energy storage has been one of the directions of preferential development due to its unique performance. In order to promote the development of energy storage technology and speed up the efficient use of large-scale energy storage system, several large-scale electrochemical energy storage demonstration projects have been successively started and completed in the world. The classification and working principle of electrochemical energy storage technologies are introduced, the main demonstration plants of large-scale energy storage system in China and abroad are summarized, as well as the installation site, scale and function in grid of electrochemical energy storage are pointed out. Then, the characteristics of main electrochemical energy storage, such as lead-acid battery, redox flow battery, sodium-sulfur battery, lithium-ion battery and so on, are comprehensively expounded. Finally, the existing problems, technical direction and future development trend of large-scale energy storage system are discussed and prospected.
During the start-up commissioning of No.1 unit (350 MW) in India Kamalanga Power Plant, two-phase short-circuit fault occurred at generator outlet during the process of synchronization. The fault causes were analyzed based on fault records, computer messages and other fault information. After the replacement of circuit breaker, the detection test for main transformer, the circuit breaker performance test, short circuit and open circuit performance test for generator, as well as the load test for units were carried out, and the results were compared with the detection test results before fault, in order to confirm that the main transformer and generator could be able to put into operation with the safety and reliability not being changed. Finally, countermeasures were proposed according to the problems exposed in the incident.
Aimed to the building mode of AP1000 nuclear power plant and the special features of poor working environment of equipment, high corrosion resistance and non-replacement of equipment after commissioning, the application of S32101 duplex stainless steel in AP1000 nuclear power plant was discussed. Besides, the chemical compositions, microstructure, welding characteristics of duplex stainless steel were introduced, and its welding process, the key control points of welding was also suggested.
During the corner feature extraction of unmanned aerial vehicle (UAV) images of high mountains and dense forests, the number of corner features was small by using traditional methods, thus a self-adaption extraction method being suggested, in which the whole process could be divided into two parts. The first part is primary corner feature extraction which determines the candidate corner feature from images with the Lv-Yan operator. While the second part is accurate corner feature extraction, which accurately extractes corner feature from the candidate corner feature with improved SUSAN algorithm. The experimental results have proved the feasibility of the proposed approach, which could extract greater number of corner feature points and run faster compared with traditional methods, as well as adapt to the corner feature extraction of UAV images in high mountains and dense forests.
Sag is one of the important parameters for the operation and maintenance of power transmission lines, which directly affects the safe and stable operation of transmission lines. Because the sag monitoring device of transmission line could not obtain the direct verification results through laboratory tests, the site observation and comparison tests should be carried out. Due to the low efficiency of traditional calculation method, a measurement method based on LabVIEW was presented for maximum sag of traditional line. Through the calculation and process analysis of sag, the calculation program of the sag was compiled by using G language of LabVIEW, in which the value of sag could be calculated quickly and accurately by inputting the required basic parameters. The results have shown that this method can ensure the accuracy and rapidity of the measured data of the sag, effectively overcome the artificial error, as well as simplify the test work. It can be applied in the field tests of the transmission line sag.
The main goal of voltage quality control (VQC) system is to ensure the qualified voltage and the balanced reactive power in substation, which is the important guarantee to improve power quality. According to the oscillation occurred in the VQC system of a substation based on seventeen-zone theory, the fixed value and control strategy were analyzed, and the control times of capacitor and the fixed value of reactive power during flat peak period were the main reasons of oscillation. So the control strategy of capacitor and the fixed value during flat peak period were adjusted and improved. Through continuous track inspection, the measures were proved effective, which can solve the problem of too many unqualified voltage points of bus line in substation and improve the qualified rate of voltage.
Taking the project of Shizimen Channel crossing part of 220 kV Qinyun (Zhuhai)-Lianhua (Macao) Power Transmission line (Lot-3) as an example, the construction technique for long distance river-crossing cable with extra cross-sectional size cable laying inside pipeline was introduced. Firstly, horizontal directional drilling machine was used to cross the river channel, then protective pipeline was laid for cable and high-power hydraulic puller was used as the pulling machine; at the same time cable support with brake equipment was used as the supporting device for transmission cable laying. Compared with the conventional construction method that only uses manual maneuvering winch as single power, the construction method that uses high-power hydraulic puller in cable laying is more safe, economic, and effective.
