The unified power flow controller with fault current limiting （UPFC-FCL） can protect UPFC from being damaged by short-circuit current when a short-circuit fault occurs in power system. Based on UPFC working principle, a parameter design method was proposed. The maximum compensation voltage was determined according to the maximum compensation capacity and rated current, and then the rated DC bus voltage was fixed. The value range of filter inductance was proposed based on the compensation capacity target, and current-limiting inductance was designed based on short-circuit current level. According to the design method above, a design example was presented that the rated voltage was 10 kV and the maximum compensation capacity was 1 MVA, and then the maximum compensation voltage which came from series converter, the rated voltage of DC bus, the filter inductance of series converter and shunt converter, the current-limiting inductance were determined. The PSCAD/EMTDC simulation results demonstrate that the design is effective and practical.
Shallow landslides happen frequently after continuous rainfall at mountain overhead transmission lines, which have many influencial factors and bring serious hidden danger to power transmission lines. Using the self-developed small-scale model flume, the experiments of shallow landslides triggered on sandy soil under simulated rainfall were carried out to investigate the displacement fields and failure modes of shallow landslides, as well as to study the inherent mechanism of shallow landslide under heavy rainfall conditions. The results show that the shallow landslides processes involve a complex course including rainfall infiltration, soil deformation, metrics suction lost, pore pressure rise and water-soil interaction. The shallow landsides under heavy rainfall are changed into fluidized flow, and the fluidized soil pushes the front soil to move rapidly.
Along with the mature power market and the constantly improvement of energy-saving technologies in China, the role of demand side resources in power grid is becoming increasingly prominent. This paper proposed a new planning mode for power grid, in which the demand side resources was regarded as the equivalent of supply side resources and should be brought into the new planning model directly. Firstly, the demand side resources were defined, the feasibility that the demand side resources were brought into power grid planning and the possible introduction part were demonstrated as well. Secondly, a new type of power grid planning mode with considering demand side resources was put forward, and the planning elements, participation subject and planning process were introduced in detail. Finally, this paper proposed specific suggestions for the promotion of the new power grid planning mode from the point of technology, management, policy and so on.
Design patterns are the solutions for some problems, which appear repeatedly in the process of software design. The application of design patterns in HVDC transmission package can reuse code, as well as make code easy to understand and dependable, and improve its reusability and expandability. The modules of HVDC transmission design software package are firstly introduced, and then the concept of design patterns is proposed. After that, the details of applying design patterns in the course of design and development to make it more extensible and reusable are described, which could provide experience and references for the design and development of similar software in the future.
In order to analyze the influences of new edition of Chinese load code on wind-induced vibration of transmission towers, wind velocity time history on a ultra-high voltage （UHV） transmission tower was simulated by linear filtering method, considering the spatial correlation. Based on the analyses of dynamic property of the structure with using finite element method, influences of turbulence intensity on the displacement response and acceleration response of transmission tower structure were compared in new and old load codes. Wind-induced vibration coefficients were calculated according to simulated results, and they were compared with those coefficients calculated in new and old load codes. The results have shown that the wind-induced vibration has an increase by 20% and has different degrees of improvement at different heights, due to the increase of turbulence intensity and peak factor for 10-m height in new load code, while steel damping ratio being unchanged.
With the complex interaction between wind and structure, the long-span roof structure belongs to wind-sensitive structures and the wind load becomes the main problem of the structure design. Taking a long-span roof of power plant as research background, the vibration characteristics of the structure were obtained. Based on the wind pressure spectrum fitting and the proper orthogonal decomposition（POD） reconstruction principle of wind pressure time-history, a modified frequency domain analysis method was presented. This method used the wind pressure data obtained in wind tunnel tests to establish the overall wind pressure model for roof, and turned it into wind pressure spectrum through fast Fourier transform （FFT）. Then the wind-induced dynamic response of roof structure was obtained based on the accurate fitting of wind pressure power spectrum, and the dimensionless formula of wind pressure spectrum was derived. Finally, the distribution characteristics of the root mean square （RMS） values of structural displacement and acceleration were studied to get the distribution characteristics of the wind-induced vibration coefficient of the roof. The results show that modified frequency domain method, which abandons the quasi-steady assumption, has higher reliability, and can be used as references for the wind-resistant design of long-span roof structures.
Along with the commencement of DC power transmission projects in the western region, the external insulation of DC transmission line has become a problem at high-altitude area. However, there is no uniform understanding on how to correct high-altitude influence on the pollution voltage of DC long-string insulators. The pollution flashover test of long string insulators in high altitude was carried out and flashover model was established. The pollution voltages of insulators at different altitudes and different degrees of pollution were calculated and the data were contrasted with the test results, which verified the adaptability of the model. The linear relationship between pollution flashover voltage and atmospheric pressure was obtained through test results, and the pressure characteristic exponent n of two typical pollution （SDD=0.05, 0.1mg/cm2） were suggested.
The forecast of wire price in grid project is difficult and the accuracy is low due to the nonlinear and non-stationary property of wire price. Therefore, the EEMD-ARMA model was built. The empirical mode decomposition （EMD） was improved by using ensemble empirical mode decomposition （EEMD）. The history price was decomposed to some smooth and periodic fluctuations components by EEMD, which was used as the input of autoregressive moving-average （ARMA） model to forecast the components price. Finally, the forecast price was obtained by the superimposing of forecast components. Taking the history data of 630/45 wire as samples, the forecast results of EMD-ARMA and EEMD-ARMA was compared, as well as the errors were analyzed, whose results verified that the forecast result by EEMD-ARMA was better than the result by EMD-ARMA in forecast accuracy. The forecast results by applying EEMD-ARMA model have a certain referencial value to the project cost control and the equipment and material bidding.
500 kV double-circuit vertical arrangement compact transmission line was introduced firstly, which was mainly used in double-circuit transmission line construction with the limit of width and height. Aimed to the unknown electromagnetic environment of this compact transmission line with phases distance compressed, and its higher requirement of electromagnetic environment in densely populated area, the power frequency electric field, audible noise and radio interference were calculated and analyzed, compared with other regular types of towers. Conclusion has been drawn that the electromagnetic environment of this new compact line could better meet the design requirement. Finally, the factors that influence electromagnetic environment were also studied to provide the basis for the optimization of tower design scheme.
DC filter is one of the critical devices in HVDC power transmission project. The configuration scheme and parameter selection process of arrester in DC filter were analyzed in-depth, and the specific expression of arrester parameters was presented. Two typical fault conditions which played decisive roles on the insulation level of DC filter were studied: ground fault on DC line and incoming switching surge on DC line； meanwhile the calculation model of these fault conditions were introduced, in which fault inductance between fault point and high-voltage side of DC filter should be considered. Based on the practical ±1 100 kV UHVDC transmission project, the overvoltage of DC filter devices was also calculated. The maximum transient overvoltage of all the DC-filter devices was presented in the calculation result, and then the final insulation level of DC-filter devices in this UHVDC project was determined according to their insulation margin, which could provide the basis for the selection of equipment and manufacturing.
The advantages and disadvantages of various short-circuit current limiting methods were analyzed. According to the issue that the single-phase grounding fault current of 220 kV bus exceeded the limit in part of the 500 kV substations of the Guangdong Power grid, the principle of limiting fault current by installing small reactance at 500 kV autotransformer neutral point was researched. The analysis results show that the installation of small reactance is the effective measure for limiting asymmetric ground fault current, and the small reactance has the advantages of small investment, high economy and reliable operation. Through the calculation of short-circuit current of 500 kV Jalin station in 2015, the effect of installing 0 40 Ω reactance on limiting current was compared to suggest that the appropriate reactance resistance should be selected between 10 15 Ω. The installation of a small reactor has no impact on the normal operation of the system, but affects the sensitivity of zero-sequence protection device, therefore, the setting values should be re-checked to prevent protection from refusing to operate.
An effective solution to reduce the single-phase short-circuit current is to install small reactors on the neutral points of 500 kV autotransformer. In the course of engineering, the AC and DC components on the neutral points of main transformer should be studied, as well as the transient voltage during switching process, in order to determine the switch mode of the small reactor. Taking the installation of small reactors in a 500 kV substation as an example, the characteristics and sources of the AC and DC components were analyzed through the recorded data on the neutral point. The simulation research was carried out to analyze the change of transient voltage during the switching process of the small reactors, and finally the parameters of the earthing switch used on the neutral points were suggested.
In order to clarify the internal risks and external risks of power system blackout, the influence of global warming, geological disasters and other external risks on the stability of power generation, transmission and distribution in power system were discussed. According to the data of blackout and damage in earthquakes of North American grid, the leading cause of extreme blackout is that faults concentrated outbreak due to external risks, such as global warming. The results of faults analysis of power distribution network show that under the extreme precipitation, a number of faults breaking out at the same time is the important reason for self-organized criticality （SOC） feature.
In order to achieve the cost-efficient operation and energy saving of the combined heat and power （CHP） plant in the multi-source heating system, and make the coal blending results more scientific and practical, heat load distribution and coal mixture burning process were integrated into one system to carry out the research of coal dirstirbution. The heat supply and power generation of the CHP plant and the peak-shaving boiler were used as the input boundary conditions of the coal blending optimization model. Considering the uncertainty of interval caused by coal quality fluctuation, and taking the coal blending of the CHP plant and the peak-shaving boiler in an economic development zone of a North China metropolis as an example, uncertainty optimization model for combination system of CHP plant and peak-shaving boiler were established under “Power Determined by Heat”, which was solved with using interactive interval algorithm. The results show that this model can not only meet the requirements of heating and power generation, unit equipments and environmental protection, but also can control the cost of coal blending in a reasonable range. The quality of blended coal optimized with the model is stable, and it can provide reasonable coordination scheme of emission reduction and coal blending economic cost for the relative decision makers according to the actual situation, in different optimized interval of blended coal types.
Domestically-developed distributed control system （DCS） was firstly used in 1 000 MW ultra-supercritical units in Shenhua GuoHua Xuzhou Power Plant, which applied chimney-tower integrated technology. With the DCS system the integration control of unit and FGD island have been realized. Based on the construction project in Shenhua GuoHua Xuzhou Power Plant, the main technical features, network structure, configuration, and implementation are introduced in practical engineering of the domestically-developed EDPF-NT+ DCS, which could further provide references for the control system design of similar units.
How to achieve the effective emission reduction of green house gases is the promising problem to Chinas power industry. For the purpose of minimizing the cost of regional power generation, and restricting carbon emission, an optimized model for regional power structure was proposed, based on the analysis on carbon capture technology. The different forms of power generation distribution in regional electric power industries were analyzed under different level of emission reduction scenarios, and the application prospect of carbon capture technology were discussed in thermal power generation. The results show that it can effectively reduce the total generation cost through adjusting monthly carbon credits, based on the annual emission unchanged. Furthermore, reducing the cost of carbon capture and solar power will become the next target of energy conservation and emission reduction in the future. The results could provide references for energy conservation and emission reduction in electric power industries.
In order to promote the development of photovoltaic （PV） generation, the government of China has promulgated a series of preferential policies such as price subsidies. Under the current price subsidies policies, PV generation enterprise can realize the profit, but it should consider national economic development to judge whether these subsidies are reasonable and sustainable for the country. Considering various influence factors of PV generation projects, the corresponding calculation model was established for the national economic costs and benefits, the economics of PV generation projects were evaluated by using national economic evaluation methods, and the influence of each main factor on the national economy of PV generation projects was quantitatively analyzed by using sensitivity analysis method. The evaluation results show that at present, the national economy of PV generation in some areas of China is still unreasonable. Finally, this paper proposed some optimization suggestions for the development opportunity and route of PV generation.
The rated current of half-speed generator used in nuclear power plant is higher than that of the normal plant, so the generator terminal box is cooled by forced air. Due to the complex magnetic field and limited space, the heat dissipation and size problem of terminal box can not be solved simultaneously, which may frequently cause the overheating problem of generator terminal box. Aimed to the typical overheating problem of generator terminal box, the analysis methods and source solution are proposed, which analyzs the reasons of overheating problems in detail by using the exclusive method, as well as carrys out comparison verification before and after modification through the simulation analysis on electromagnetic heating. Therefore, the overheating problem of generator terminal box could be early found in the design period.
Due to the increasing demand of regional heat supply, supercritical technology has been gradually applied and promoted in 300 MW cogeneration units. Technology optimizations have been carried out on the aspect of energy saving, while challenges have also been presented to unit operation and commissioning. In a 2×350 MW power plant, the features of 350 MW supercritical cogeneration unit are introduced, and the key technology of its commissioning is analyzed to suggest a solution for the problems in commissioning. The proposed commissioning technologies could be references for similar units commissioning.
The heat loss characteristics and steam distribution optimization experiment of 1 030 MW turbine manufactured by Harbin Steam Turbine Co., Ltd. are introduced, including steam distribution optimization scheme and its effect. Through the turbine test with condition variation, the results show that hybrid sliding-pressure operation is more beneficial to improve the efficiency of HP cylinder and reduce the power consumption of feedwater pump than fixed pressure operation, but the cycle efficiency will decrease with the decrease of new steam pressure. Therefore, there is a certain space-optimized in the parameters of hybrid sliding-pressure operation. This optimization design could provide references for the design of similar units.
In order to ensure the electrical equipments in Shazhou 750 kV substation to be insulated totally with composite material, the key technologies of the composite insulating materials adopted in 750 kV substation was researched, including the technologies of improving the sand resistant and ultraviolet resistant performance of composite insulating materials, the molding technology of elasticity modulus of epoxy resin insulating material, and the development technologies of 750 kV main transformer, HP reactor bushing, 750 kV disconnector with composite post, 72.5 kV circuit breaker with composite column and so on. The successful accomplishment of these key technologies is significant to the safety and reliability of first application of composite insulating material in 750 kV substations.
HVDC power transmission system that works in monopolar operation will generate neutral current causing DC magnetic biasing of transformer, which will lead to the adverse reaction of transformer, such as local overheating, vibration increase and noise increase. The influence of DC magnetic biasing on transformer and the main suppression method of DC magnetic bias are analyzed. The new device topology of supressing transformer DC magnetic has been proposed, based on the principle of DC electric potential compensation. Through the fault simulation, the parameter selection for devices has been implemented，which could serve as references to relevant projects.
In order to achieve the optimal allocation of emission quotas, taking power industry in one region as an example, an optimization model is proposed for emission trading, in which SO2, NOx, CO2 were considered as the main atmospheric pollutants, with considering the factors like power enterprises operating resources cost, power cost, pollutant treatment cost, pollution emission reduction performance, the trading price and quotas of pollutant emission. Then, the impact of these factors on power industrys pollutant trading and power plant operation were compared and analyzed by using multi-scenario analysis method. The results show that when the trading price of emission quotas and the performance price of government are changed, the electricity generation of each power plant and the regional purchased electricity are unchanged, but the pollutant trading conditions of each power plant change and a variety of transaction types appear. This model can effectively solve the regional environmental governance and pollutant emission reduction of power industry, as well as can achieve the effective control of regional pollutant total emissions and energy structure optimization, which can provide references for the regional energy planning in the future, the regional environmental quality improvement, the optimization of power plant operation and the establishment of regional pollutant emission trading mechanism.
In unattended substations, as power transformer serves as common and major equipment, its operation status should be monitored at all times, and corresponding alarms should be triggered when abnormal situations occur. A detection method for transformer oil leakage based on color feature was presented, in which abnormal area could be detected through difference method, and its H-S Color Histogram could be analyzed. When the tawny part of images before and after changed much, it could be determined that oil leaks abnormally. The experimental results show that this method is easy to carry out, the accurate detection of transformers oil leakage, and it can also well eliminate the influence of shadows on testing.
There are many risks in the early stage of the construction of 1 000 MW level thermal power projects, and the prevention and control of these risks are critical to investors. Therefore, risk elements transmission model was built, which could provide decision-making basis for risk managers. According to the characteristics of risk elements in the early stage of 1 000 MW level thermal power project, the distribution of risk elements were analyzed. On this basis, the risk elements transmission model in the early stage of 1 000 MW level thermal power project was built to determine the occurrence probability of risk elements in the early stage by using Monte Carlo simulation method, and to discuss the risk elements transmission structure in the early stage of thermal power projects. Then the risk elements transmission algorithm with BP neural network was established in the early stage of thermal power projects, the example simulation was implemented to build a learning sample set, with which the network was trained and tested on Matlab 7.0 platform. The test results have shown that the model is correct and feasible, which can effectively control the project investment risk.
