In order to study the impact of bipolar blocking in ±800 kV UHVDC power transmission system from Jinping to southern Jiangsu on the stability of receiving-end system in Jiangsu power grid， the possible influence of bipolar blocking with transmission power of 4 000 MW on the stability of receiving-end system in Jiangsu power grid were researched from various aspects by using advanced digital power system simulator （ADPSS）， based on the typical data of peak load in Jiangsu power grid in the summer of 2013. The research results show that the stability over-limit didn’t happen in the key transmission channels of southern Jiangsu after bipolar blocking; the generators near Tongli converter station could maintain the power angle stability; bus voltage of 500 kV southern Jiangsu converter station had a significant voltage fluctuations after bipolar blocking， but Jiangsu grid could still maintain stable operation; the frequency of Jiangsu grid had a slight drop after bipolar blocking， however the frequency stability could still be maintained. The research results have practical significance to the research on the security and stability of receiving-end system in Jiangsu power grid.
In the wind loads on serial 2-bundled conductors， the drag force of the leeward conductor can be influenced by the vortex shedding of the windward conductor. In order to investigate the wind load shielding effects of serial 2-boundled conductors with the variation of wind velocity and bundle spacing， the overall drag coefficients of three types of model conductors were tested in wind tunnel under different wind velocity and bundle spacing. Meanwhile， the drag coefficient of one type of commercial conductor was tested and compared to examine the accuracy of the model conductor’s simulation to the commercial one. The results show that the simulation by model conductor has high accuracy. The drag coefficients of the lee-ward conductors as well as the global drag coefficients of the 2-boundled conductors grow with the increase of bundle spacing， but they are all much smaller than the value recommended in the current design standards. The global drag coefficients of the 2-boundled conductors decrease at first， and then rise with the increase of wind velocity; however， they are all much smaller than that of a single conductor in all wind velocity. The recommended value of the global drag coefficient of the multi-bundled conductors in the current design standard is on the high side and can be reduced by taking the shielding effect into consideration.
As an important part of smart grid， the metering automatic system （MAS） should be improved to meet the access of distributed power generation. The definition and overall framework of MAS， and the operation status of MAS in Guangzhou power grid were introduced. Based on the business demand of Guangzhou power supply bureau Co.， Ltd.， the overall function deployment program for new MAS was designed. Then the data acquisition， line loss rate and online/offline time statistics of the distributed power sources that connected to power grid were studied， so as to propose some suggestions for the development direction of MAS in Guangzhou power grid.
Because of the pull effect of flexible bus， strong interaction exists in substation equipment interconnected by flexible bus during severe earthquake. The substation equipment was simplified as a single degree of freedom system with lateral stiffness， and the flexible bus was simplified as a spring with variable stiffness. The effective stiffness of the spring was obtained according to the suspension theory. Then a kinetic model of single span structure was built for the electrical coupling equipment interconnected by flexible bus， and solved by using the Newmark-β method combined with Newton iteration. Through the analysis of the structural features and equipment parameters， it shows that the tension stiffness of flexible bus has a nonlinear growth with horizontal span， and the characteristic frequency of coupling system is influenced by the natural frequency of standalong equipment， the quality ratio and the effective stiffness of flexible bus. It is found that there is a critical rise-span ratio under seismic action. When the rise-span ratio of flexible bus is smaller than the critical ratio， large tension generates in the bus， and the seismic response of equipment is greatly influenced by equipment frequency. So during the seismic design of substation equipment interconnected by flexible bus， the influence of critical rise-span ratio must be considered.
Firstly， the current overall situation and features of power equipment overheating were summarized， the basic theory and research progress of electrical contact were introduced， and then some specious understandings of electrical contacts were clarified. Secondly， combined with the service condition and natural environment of power transmission and transformation equipments， the deterioration mechanism and synergistic reaction of electrical contact element were discussed from aspects of corrosion （galvanic corrosion， electrical damage and oxidation corrosion）， temperature factor and fretting. Finally， the current problems existed in electrical contact technology and construction in the power system were discussed， and some suggestions were proposed for the reliability improvement of electrical contacts.
In order to study the application prospect of aluminum conductor with reinforced core of carbon fiber （ACCC） in new 500 kV overhead power transmission line project， taking a typical 500 kV single circuit AC line as research object， three kinds of ACCCs with 360-450 mm2 aluminum sections were selected to compare for conventional 630 mm2 ACSR based on the principle of equal current-carrying capacity. Through the comparison of current-carrying capacity， sagging characteristics， icing overload capabilities， load characteristics and swing angles， and the comparison ofthe initial investment of different conductor schemes， the economic performance was analyzed with using annual cost method. Finally， the critical price of ACCC was calculated and the conditions for ACCC’s economy advantages were summarized.
The mechanical characteristics of flange joint with slope change on transmit-electricity steel tube tower were analyzed by using finite element software ANSYS， and the influence of joint type， the thickness of gusset plate， the thickness and height of stiffened plate on the mechanical behavior of flange bolt were studied. The results show that different from ordinary rigid flange joint， the bolt tension of flange joint with slope change is uneven. Further analysis show that the size of gusset plate is much larger than that of stiffened plate， which is the main reason for uneven bolt tension. Based on the analysis results， considering uneven bolt tension and the influence of shear on bolt， new design method and some suggestions were proposed to provide references for the practical project.
Aimed to the anti-galloping ability of phase to phase spacers used on power transmission lines， taking ADAMS as research platform and based on the parameters and galloping records of No. 108-109 overhead transmission lines at the 500 kV Guanmen reservoir in Geyungang of Hunan province， four phase to phase spacers were arranged and the simulation model of virtual prototype was built for this transmission line span. The simulation analysis was carried out on galloping under specific weather conditions， and the displacement data at right-phase span 1/4， 1/2 and 3/4 were used to draw the displacement curve and get the stable amplitude of the galloping. The result shows that the galloping amplitude is 5.0 m before the installation of phase to phase spacers; however， it turns to 3.5143 m， and drops 29.714% after the installation， which has proved that the phase to phase spacers can improve the anti-galloping ability of transmission lines.
In order to improve the reliability of protection configuration for 500 kV station transformer in HVDC converter station， the typical short circuit was analyzed and calculated， in which the parameters and connecting pattern of 500 kV HV station transformer in Jiangmen converter station of Nuozhadu-Guangdong ±800 kV UHVDC transmission project was taken as the model. The protection configuration scheme of 500 kV HV station transformer connected 500 kV AC distribution device with 3/2 wiring was proposed， which included the differential protection of transformer and lead at high-pressure side. The configuration criterion of failure protection at high-pressure side of 500 kV station transformer was suggested， which could provide a better solution for the misstrip and maloperation problems of failure protection existed in the converter stations built before. The research results have been applied in the Jiangmen converter station， which will provide references for the protection configuration of HV station transformer in converter station.
The equivalence relation between the live testing and offline testing of dielectric loss in capacitive devices was studied. The dielectric losses of three replaced CTs were measured with using live testing device， the dielectric losses of three CTs were obtained under different voltages. The difference between the live testing and offline testing of dielectric loss was also analyzed. The results shows that different sample voltage might cause different measurement results of dielectric losses. The mechanism of this phenomenon was analyzed in theory， which showed that the measurement results of dielectric losses under equipment operation voltage might be more reasonable for accurately determining equipment insulation status.
DC power distribution network is a new power supply system. According to the load unbalance problem and the demand of stable and reliable power supply in three-wire DC distribution network， a new bi-directional voltage regulating balancer was proposed for DC distribution network. The bi-directional voltage regulating Buck-Boost conversion circuit was applied in the voltage balancer， which could not only solve the voltage balancing problem of positive and negative electrodes in three-wire DC distribution network， but also balance the voltage fluctuation and maintain the voltage stability at output end. Firstly， the voltage balancer with bi-directional voltage regulating was analyzed through small signal state model based on state space averaging method. Secondly， based on the characteristic of the proposed voltage balancer and its modeling analysis， the control strategy with the control technology of bi-directional complementary pulse width modulation （PWM） was proposed and analyzed. Finally， the simulations for two loads such as unbalance loads and voltage fluctuation were carried out by applying PSCAD to verify the ability of voltage regulating and balancing of voltage balancer， which showed the correctness of the theoretical analysis.
The traditional control technology of doubly fed induction generator （DFIG） is based on stator flux-oriented control technology， but not considering wind speed fluctuation， the non-linear and robust control of wind generator. So a coordination control technology of DFIG-ESS （energy storage system） was proposed based on Hamilton function， to deduce the Lyapunov’s stability region of controller parameters， and to prove the stability condition of controller. Then， the control test system of DFIG-ESS was designed and built based on MSP430 MCU， which has achieved good results through experiments under random wind. The research results have established the foundation for the hardware platform design of nonlinear and robust control system of DFIG.
In order to save the time of bearing lube oil flow distribution in the actual commissioning process of 1 000 MW power unit， and reduce the complexities of commissioning process due to the restriction of lead bearing type， a function model that could fit different bearing oil flow distribution characteristics was proposed， based on the research of commissioning data of different units. The concept of progressive comparison method was presented through the comparative analysis on the lube oil amount of bearings with different sizes. The method that combined function model and progressive comparison was used in the commissioning process of elliptic bearing lube oil flow distribution in a power plant. The results show that the bearing temperature can reach excellent standard after 168 h operation at full load. Therefore， this commissioning method can not only ensure the commissioning effect， but also save the commissioning time.
In order to decrease auxiliary power consumption rate and save energy， reduce energy consumption， the single-row layout was firstly successfully applied in the air and flue system of 660 MW ultra-supercritical unit of Bulian Power Plant. Through adopting highly performance auxiliaries， I & C equipment and the reasonable configuration of control system， the operating reliability of single-row configuration was guaranteed. According to the actual state of operation， a comprehensive comparison was carried out between single-row and double-row configuration in terms of technology， investment economy and operating economy. The results show that total investment of air and flue system with single-row configuration is almost same as that with double-row configuration， but the operation efficiency of single-row configuration is increased by 3%-4%， and the single-row fan has characteristics of flexible operation， convenient maintenance and steady operation.
With the background of energy conservation and environmental protection， some application achievements of type selection and design optimization for heat engine equipments in large thermal power plant were analyzed， including steam turbine， boiler and main auxiliary equipments. The characteristics and shortcomings of equipment selection optimization of thermal power engine were pointed out， as well as some measures and suggestions were proposed， which have provided reference for the heat engine equipment selection in 600 MW and above large thermal power units.
In order to break the monopoly of porcelain insulating materials in UHV and EHV power transmission project， and reduce the equipment cost， taking Shazhou 750 kV substation as an example， the feasibility of the comprehensive application of high temperature vulcanized silicone rubber insulating materials in 750 kV substations was researched. Through the analysis of the performance of high temperature vulcanized silicone rubber composite insulating materials， including the damage resistance， the anti-pollution flashover performance， the sand resistant performance， the ultraviolet resistant performance， it is showed that the composite insulating materials can meet the service life requirement of 40 years under the terrible natural environment conditions in Shazhou substation. Furthermore， by analyzing the economic efficiency in the whole life cycle， it is proved that the composite insulating materials needs less investment than porcelain. Therefore， it is concluded that the comprehensive application of composite insulating materials in equipments of 750 kV substation is technically reliable and economically reasonable.
A new design method of expanded diameter conductor with large section was proposed， where the outer layer of aluminium wire was placed closely by round line and the support layer was placed sparsely by section line. Based on the requirements of electromagnetic environment control and transmission capacity， the boundary conditions for structure design of expanded diameter conductor with large section were determined: the outside diameter was 42.88 mm， and conductive cross section was 780 mm2. The structure and parameters of JLXK/G2A-780（1000）/80-42.88 were designed， and the technical and economic analysis showed that its initial investment was smaller than that of 8×1 000 mm2 conventional wire scheme. The economy of expanded diameter conductor was better than that of 8×JL/G2A-1000/80 wire scheme due to the low electricity price and low loss hours in total life cycle. With the help of the simulation analysis on the section stability of expanded diameter conductor， and the structural stability verification of trial production samples， it both show that the critical strand jumping tension is 25%RTS （rated tensile strength）. So the expanded diameter conductor with large section （JLXK/G2A-780（1000）/80-42.88） has good section stability， and is suitable for the projects that have high electromagnetic environment requirements and low utilization hours.
In order to comprehensively understand the security situation of heating surface tube made of X20CrMoV121 steel after long-term operation in thermal power plant， the mechanical performances tests， microstructure analysis and high temperature creep rupture strength tests were carried out on final superheater tube and high temperature reheater tube in a power plant. The results show that compared with original tubes， the strength of operating tubes decreases; when the precipitation phase occurs ripening， the local lath characteristics becomes weak， substructure appears in the martensite laths， the dislocation density obviously declines; and the substructure dislocation has the trend of directional arrangement， but the high temperature creep rupture strength is still higher than the design value. From the comprehensive analysis it is concluded that although the X20CrMoV121 steel tubes have aging phenomenon in some extent after 12000-hour operation， they still can meet the requirements of safe operation under design conditions.
With the development of wind power scale in Gansu， the feature of anti-peaking of wind power makes the peak regulation of power grid more and more serious. So for the safe and stable operation of power system， part of grid-connected wind turbines have to be removed， which may cause great waste of equipment. In view of the above situation， high energy-consumption enterprises were suggested to actively participate in the wind power consumption and the peak regulation mode of power grid was proposed. Then， the internal transfer load and increasing load in high energy-consumption enterprises were studied with considering the constraints of wind power’s price and peak regulation， and the fluctuations of wind power output were calculated with using optimal prediction function to control optimization algorithm. Finally， simulation research was carried out in Matlab platform， according to the actual wind data and the transfer load of high energy-consuming enterprises. These results show that the wind power output can be smooth. Compared with the traditional peak regulation mode， the active participation in peak regulation of high energy-consumption enterprises can not only improve the wind power consumption capacity in province， but also relieve the pressure of peak regulation of power grid. Meanwhile it can save the electricity cost of high energy-consumption enterprises， in the support of relevant electricity price policy.
With the transformation of the market economy， the power industry is undergoing preliminary market-oriented reform. In recent years， the power industry is facing a grim situation， in which the growth rate of the power demand is slowing， and the asset-liability ratio of power grid enterprises increases continuously. In order to ensure the healthy development of power grid enterprises， it need to effectively manage the investment processes of projects and make it effectively connect with the business development goals. The project portfolio models in special fields for power grid enterprises were studied， by taking a power supply company that belonged to Chongqing Municipal Power Corporation as an example. A multi-objective decision model was established for grid project portfolio based on the portfolio theory. Then， the weight of the target was determined and the model was solved， according to the business situation of enterprise and the variable weight theory. Finally， the solution of project portfolio was simply verified， which showed that the model had certain practical application values.
During conductor tension stringing process of power transmission line， the application of intelligent control system for tension machine will help operator control multiple tension machines， which not only make the control of conductor tension more precise， but also can save the manpower cost. The application of bus remote control technique makes operators away from the harm of bad environment to human body， such as noise， blown sand， rain， snow， solarization and so on， as well as can reduce the labor intensity of operators. The stringing construction of conductor turns much safer with the function of fault self-diagnosis and solving in the control program， meanwhile operators can observe the walking-plate operation and the pulling rope jumping from slot with the help of auxiliary wireless video monitoring system.
A general graphical method for the rigging force calculation of derrick supported by inner suspension & inner （outer） backstay is proposed for tower erection in sections and in vertical state. Based on algebraic method， the calculation coefficient of each main rigging stress is provided under the condition of given layout parameters， forming a general graphical calculation method in combination with the calculation principle and formula of rigging stress. as well as quickly calculating the rigging force. With this method， the force of each rigging can be calculated easily ， and the force change can be predicted when the layout conditions change.
