This paper analyzed wind turbine model used in offshore direct-drive permanent magnet synchronous generator and its operation characteristics. Based on improved direct torque control technology with adaptive full-order stator flux observer and on-line identification of stator resistance, induction motor was used to simulate the output characteristic of wind turbine. Simulation results show that the improved direct torque control decreases the current and torque ripple of induction motor at low speed range in traditional direct torque control, which is more suitable for offshore direct-drive permanent magnet synchronous generator running in low-speed.
The energy and environment crisis are arousing the world to search for new and clean energy resources. The geothermal energy has advantages of steady and continuous supply, high utilization coefficient, etc. As a new and clean energy development direction of rich resources, the enhanced geothermal system （EGS） is gaining increasing attentions across the world. There are mainly two kinds of research methods: （1） the direct engineering practice research through field test site； （2） the theoretical analysis through numerical simulation. This paper introduced the present research situation of EGS at home and abroad, including the borehole exploring, hydraulic stimulation, seismic monitoring and circulation test during practical field tests, and various numerical simulation studies, especially for the building of several main heat reservoir models: the regular fracture network model, the stochastic fracture network model, the equivalent porous medium model, etc. And then, the research situation in dual energy equations model was introduced. Finally, this paper analyzed and forecasted the development trend of EGS research, which could provide reference for the R&D of EGS in China.
For low-voltage distribution network with photovoltaic （PV） power plants, when voltage level reduces, the voltage drop on transmission line is not only influenced by reactive power, but also fluctuates more obviously due to active power. The voltage fluctuation components caused by active and reactive power are algebraic sum relations, so the reactive power compensation can make up for the voltage fluctuations caused by the change of active power to a certain extent. Taking the optimal system operation cost as the target function, including the reduced power loss cost of distribution network after compensation and the added cost of reactive power compensation device, this paper established the optimization mathematical model of reactive power compensation for distribution network with PV power plant. The model considered the reactive power regulation capability of grid-connected inverter in PV power plant, and adopted the improved multi-organizational particle swarm optimization （PSO） to solve the programming model. Finally, the accuracy and validity of the model and algorithm were validated by example analysis.
The construction objectives of new generation of smart substation, which are “highly integrated system, reasonable structure and layout, advanced and applicable equipment, economical, energy saving and environmental protection, support of integrated control”, put forward new requirements for all aspects of smart substation construction. The general layout of electrical system is one of the important contents of substation design, which can significantly reflect the reasonable structure and layout of substation. Combined with the actual situation of engineering construction, this paper collated the ideas of general layout optimization of the electrical system, organized and summarized the influence factors of the layout of power distribution unit and electrical system. Based on the applications of the new equipments and techniques, such as the optimization of the main electrical wiring, the integrated smart devices, and container type building, this paper proposed the optimization design scheme with taking the typical schemes in general design as boundary conditions, and technically compared the scheme with current smart substation. Finally, the direction of layout optimization for four types of new smart substations was proposed, including 220 kV outdoor air insulated switchgear （AIS）, 220 kV outdoor gas insulated switchgear （GIS）, and 110 kV outdoor AIS, GIS.
The validity of the application of fast splitting criterion in multi-channel interconnected power system was studied. According to the system oscillation mechanism, taking a three-machine power system with asynchronism splitting as an example, this paper focuses on the fast splitting criterion for the channel out-of-step oscillation, and studies the theoretical correctness that power angle change rate criterion and active power change rate criterion were applied in the oscillating model of this three-machine system with asynchronism splitting. The rationality of this criterion used for multi-channel asynchronism splitting was preliminarily verified with using BPA simulation in the three-machine system, as well as the applicability of fast splitting criterion in complex multi-channel power system. Finally, this paper further validates that the fast splitting criterion could accelerate the splitting process of remaining channel and improve the stability of the subsystem during multi-channel asynchronism splitting, through the model simulation of China Southern Power Grid.
Based on the analysis on the damaged towers caused by conductor galloping in transmission lines and its characteristic statistic, it was found that the joint bolts were the weakest point of whole tower in anti-galloping performance, through the analysis on the bearing behaviors of tower and joint bolts. According to the manufacture and construction characteristics of existing joint bolts, the possible factors to locking performance of joint bolts had been tested and analyzed by using the locking performance test method of existing fasteners. The results show that the initial pre-tightening force is the most critical factor to the locking performance of joint bolts. Through the comparison test on the performances of different lock types, it is found that the double-nut connection types can present excellent locking performance with proper installing method. According to the test results and the construction process of transmission tower, this paper proposed some promotion measures and improvement suggestions for the selection and construction method of joint bolts, which could provide guidance and reference for the anti-galloping reconstruction of transmission tower.
The multi-circuit-on-same-tower power transmission technologies are more and more often used in areas with scarce transmission corridor sources or with special geography environments. Along with the voltage grades increase of multi-circuit-on-same-tower power transmission systems, the reliability of these transmission systems has an important influence on power systems’ security, stability and reliability. The traditional combined-model-based methods in reliability evaluation have the disadvantages of complex models and intensive computation. The reliability evaluation method based on separation models can overcome these disadvantages. Adopting the reliability assessment method based on separation models, this paper provided the probability formulas of different types of faults in four-circuit-on-same-tower transmission systems and four-circuit-on-two-towers transmission systems. And then according to the common faults’ outage frequency and repair time, this paper evaluated and compared the reliability of four-circuit-on-same-tower power transmission systems and four-circuit-on-two-tower powers transmission systems. It is pointed out that the reliability of four-circuit-on-same-tower power transmission systems is lower than that of four-circuit-on-two-towers power transmission systems.
The rotary clamp spacer-damper is a new hardware. And because of its short time in application and the influence of style, amount and installation position, it is difficult to put forward a desirable evaluation method for its anti-galloping effect. With considering these factors, and in order to avoid complicated vector operation, the differential equations of conductor motion were derived from the Lagrange equation, when the conductor spacer-damper was covered by ice； and the time-responses of conductor galloping under the conditions of different kinds of spacers and different installation positions were calculated. Then, an evaluation method of anti-galloping effect was proposed based on the designing parameters of the conductor spacer-damper and the fuzzy mathematics theory. The analytic results show that the rotary clamp conductor spacer-damper has a better effect of anti-galloping. In addition, since the torsion angle of the sub-conductor also could affect the galloping prevention effect, therefore, an improved method of increasing the conductor torsion angle was put forward.
In order to evaluate the service condition of Cu/Al terminal connector under industrial air pollution environment, the NaCl+NaHSO3 salt fog spray experiment was carried out to study the atmospheric corrosion behavior of the Cu/Al terminal connector, and the effect of the atmospheric corrosion on the electrical properties of the terminal connector was investigated. The results show that the corrosion products of the terminal connector are mainly composed of Al, Sn and Pb sulfates and water-soluble chlorides. In the initial stage of corrosion, pitting corrosion takes place on the Al oxide film at the Al/Sn-Pb solder interface due to Cl-ions. In the late stage of corrosion, uniform corrosion takes place on the both sides of the Al/Sn-Pb solder interface due to the HSO3-ions, which even results in the fracture of the terminal connector along the Al/Sn-Pb alloy interface, as the corrosion time increased. Moreover, the electrical resistivity of the Cu/Al terminal connector increases slowly in the initial corrosion stage and increases rapidly when the corrosion time is increased more than 2 days. These research results have reference significance to the operation management of the Cu/Al terminal connectors.
The electromagnetic compatibility research and standardized construction of power communication equipment are weak links relative to relay protection and automation device. In order to solve this problem, this paper proposed the architecture of electromagnetic compatibility standard system and standards system table for power communication equipment in power electromagnetic environment. Firstly, the requirements of standard system were proposed from four aspects: the power communication equipment’s electromagnetic environment, electromagnetic compatibility requirements and measurement methods, electromagnetic protection, as well as operation and maintenance management. Then, combined with the hierarchical classification method of IEC electromagnetic compatibility standard system framework, the architecture of 2D standard system of power communication equipment electromagnetic compatibility was put forward, as well as the corresponding standards system table, which contained three categories and eight standards. The research results can be used to guide the planning and construction of electromagnetic compatibility standard system for power communication equipment.
In recent years, in the excavation of backfill foundation in northwest 750 kV UHV power transmission project, the inclined column and oblique top surface of foundation in vertical direction of the tower plate has been gradually widely used in the foundations of terminal tower and corner tower, whose column top surface is vertical to the inclined column ridge, and no longer a horizontal plane. The straight anchor bolt has the same slope with column, and the inclined anchor is fixed on reinforced concrete column. This paper introduces the characteristics of this new type of tower foundation, and describes the calculation points and control difficulty of the column template with irregular shape, the unequal-length column’s main reinforcement and the measurement positioning of foundation construction technology, which could provide references for technical workers.
Along with the development of wind power from “lakeside” to “high mountains” in Jiangxi province, wind farm on high mountains will be the main force in the future. There are multiple factors to consider in the site selection of wind farm, and some of them are qualitative factors, which are hard to be comprehensively analyzed. In addition, wind farm on high mountains has its own characteristics compared with it in plain area and offshore. Site selection method was suggested on the basis of an evaluation index system for site selection of wind farm on high mountains, in which the feasibility and the advantages and disadvantages of site selection were discussed through the comprehensive analysis of each evaluation index, and the optimal wind farm among alternative ones was picked out. In the end, the feasibility of the site selection method was verified by practical application.
In order to satisfy the new Chinese standard of effluent water drained from nuclear power plant, the improvement principle of radioactive waste liquid processing system in AP1000 inland nuclear power plant was determined, based on the analysis of the sources and characteristics of radioactive waste liquid produced by AP1000 reactor. Several improving measures such as adopting chemical flocculation, adding ion exchange beds and using macroporous ion exchange resins were developed based on the advantages and disadvantages comparison of several process programs. Demonstration tests were carried out and the results showed that the improved process could meet with the requirement of radioactive waste liquid processing system in inland AP1000 nuclear power plant.
Under the condition of safe operation, the efficiency of unit under variable operation condition and its economic benefit can be increased through the optimization of turbine’s initial and final parameters, which has very important significance to energy conservation and emissions reduction of thermal power units. The universal calculation method of power and back pressure characteristics was used to determine the corrective curve between turbine power and exhaust pressure, then the equal efficiency points between adjacent operating modes of circulating water pumps under each load condition was determined, and the equal efficiency curves was obtained. Based on the operation optimization of circulating pump, the optimization model of unit’s initial pressure and back pressure was established, combined with reverse method of variable condition theory. Taking C300-16.7/0.43/537/537 unit in a power plant as example, the optimal initial and back pressure under different operation conditions were obtained by using improved particle swarm optimization. The results show that the main steam pressure and exhaust pressure at the maximum power supply efficiency can be obtained by adjusting steam distribution mode under certain load operation of unit, which can provide reference for the operation parameters optimization of thermal power unit.
In order to better analyze and evaluate the construction effect of power distribution automation pilot projects and improve the intelligent level of distribution network, this paper proposes a benefit evaluation model for power distribution automation, as well as the benefit evaluation method. In the view of economic benefits and social benefits, the economy of power distribution pilot projects was analyzed and evaluated systematically and objectively, so as to provide references to the optimization of power distribution automation pilot projects.
In order to rationally determine the scale and layout of charging station for electric vehicle, the index of investment cycle cost （ICC） and user convenience of electric vehicles are presented. On this basis, taking the minimum cost of investors and user as target, the scale and layout of charging station was determined. The electric vehicle in rush hour traffic was simulated by the objective function； taking the power of transmission line, the upper and lower limit of reactive power compensation, as well as the battery number and service radius of charging station as constraints, the initial construction investment, network loss and the investment of new transmission line as ICC, the user convenience was measured according to the electrical power consumption expense from user to charging station, and the cost of investor and user cost was comprehensively considered, as well as the operating limits of power grid. The layout of charging station was optimized with using Chaos Particle Swarm Optimization algorithm, and the sensitivity to initial value and ergodicity of chaos were used to initialize the population； then, the chaotic sequence was formed and the corresponding relationship of variable range was optimized through logical mapping function. Taking a district as an example, the effectiveness of the algorithm was demonstrated, compared with Particle Swarm Optimization
