Table of Content

23 August 2013, Volume 46 Issue 8

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Special Contribution

Contribution to PM_2.5 of Atmospheric Pollutant Emission from Thermal Power Sector and Emission Reduction Countermeasures

MO Hua, ZHU Fa-hua, WANG Sheng

2013, 46(8):  1-6.  DOI: 10.11930/j.issn.1004-9649.2013.8.1.5

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During the 11^th five-year period, the total installed generation capacity in China increased to 962.19 GW of 2010 from 508.41 GW of 2005, of which thermal power increased from 384.13 GW to 706.63 GW. The coal consumption for electricity increased to 1.511 billion tons of 2010 from 1.063 billion tons of 2005. Dust emission amount from thermal power sector in China was 2.184 million tons in 2010, SO₂ emission was 9.844 million tons, and NO_x emission was 9.542 million tons. Research shows that PM₁₀ total emission amount in China was 37.973 million tons, and PM_2.5 total emission amount was 22.784 million tons in 2010. PM_2.5 emission of primary fine particulate from thermal power sector in 2010 was 1.008 million tons, PM_2.5 emission of transformation from SO₂ was 3.50 million tons, PM_2.5 emission of transformation from NO_x was 2.655 million tons and PM_2.5 emission of transformation from SO₃ was 1.073 million tons. All of PM_2.5 emission from thermal power sector accounted for about 36.1%. In order to reduce PM_2.5 emission, some measures are proposed including strengthening operational management of environmental equipments, formulating new economic policies to guide enterprises to reduce emission voluntarily, and installing wet ESP after wet FGD.

Analysis and Prediction of China’s Electricity Demand and Supply in 2013

SHAN Bao-guo, TAN Xian-dong, WEN Quan, HAN Xin-yang

2013, 46(8):  7-10.  DOI: 10.11930/j.issn.1004-9649.2013.8.7.3

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Based on an analysis of China’s power demand and supply from January to May in 2013, a forecast was made to the country’s power demand and the balance of power demand & supply in the whole year of 2013 and some measures were proposed to guarantee the c power supply. It is predicted that China’s total electricity demand will reach 5 231~5 332 TW·h, growing by 5.5%~7.5%; the net installed generation capacity will increase by about 90 million kilowatts with the country’s total installed capacity of 1.24 billion kilowatts by the end of 2013; the country’s power demand and supply will be in balance in the whole, but varied in regions with, the power demand being a little bit higher than the supply in the North China, being in balance with the supply in the East, Central and South China, being lower than the supply in the Northeast and Northwest. China.

Column of Wind Power,PV Power and Energy Storage

Studies on Guangxi Provincial Standard for Microgrid——Technical Guide for Interconnecting Microgrids with Distribution Systems with Voltages of 10 kV and below

HUANG Xiu-qiong, ZHAO Min, HUANG Shao-wei, SHEN Chen, Chen Wei-dong, Gao Li-ke

2013, 46(8):  11-15.  DOI: 10.11930/j.issn.1004-9649.2013.8.11.4

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There is no published standard dedicated to microgrid in China at present. This paper introduces the works for formulating a Chinese provincial standard for microgrid, namely“Technical guide for interconnecting microgrids with distribution systems with voltages of 10 kV and below (DB45/T 864-2012)” , which is based on the IEEE 1547 series of standards with consideration of the local conditions in China, especially those of Guangxi Province. A brief introduction was made to the formulating process and framework of the standard, and several special technical issues were discussed in the standard, which may provide a reference for formulating follow-up standards.

BESS for Wind Power “Peak Shaving” Control and Capacity Configuration

JIN Wen-tao, LI Jian-lin

2013, 46(8):  16-21.  DOI: 10.11930/j.issn.1004-9649.2013.8.16.5

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In order to reduce the peak-to-valley D-value of hour-level wind power output power, and lower the negative impacts of the intermittence and fluctuation of the wind power on power grid, a wind power peak-shaving control strategy was proposed according to the hour-level wind power output instruction based on the short-term wind power forecast technology; the battery energy storage system (BESS) was used to lower the hour-level valley-to-peak difference of wind power, and the wind power fluctuation of the synthesized storage wind power output in every time scale was restricted within a certain limit of bandwidth. The paper put forward a normal distribution-based energy storage power calculation method and a BESS-based optimization control strategy, analyzed the relationship between the part peak-shaving control strategy by BESS and the energy storage capacity Simulation results proved that the energy storage capacity configuration was valid and feasible under such control strategy.

Forecasting and Analysis on Large-Scale Energy Storage Technologies in China

YAN Xiao-hui, XU Yu-jie, JI Lv, CHEN Hai-sheng, TAN Chun-qing

2013, 46(8):  22-29.  DOI: 10.11930/j.issn.1004-9649.2013.8.22.7

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The domestic and international development and application status quo of large-scale energy storage(LSES) technologies is introduced in this paper. A forecasting model is established for development demand of LSES technologies and a prediction is made of the installed capacity rate, economic values and social demand. The economic values include engineering and ancillary services, and the social demand includes environment and social jobs. A development program is proposed based on LSES techno-economic analysis. The analysis results show that the installed capacity of LSES in 2020 will reach 33.6~80 GW with the storage rate of 1.74% to 4.13%, and the economic values of engineering and ancillary services will reach up to 14.78 billion to 160.32 billion dollars and 24.36 billion to 58 billion dollars, respectively, with a benefit of reducing CO₂ emission of 2.43~36.19 million tons.

Hybrid Damping Control Strategy for LLCL Filters of PV Systems

LI Jia-jun, ZHANG Jian-cheng, LI Qian, LI Fan

2013, 46(8):  30-34.  DOI: 10.11930/j.issn.1004-9649.2013.8.30.4

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In order to make the photovoltaic(PV) system meet the standards on grid-connected current harmonics, an LLCL filter-based inverter is developed with a hybrid active and passive damping control strategy. By setting the parameters of the hybrid damping scheme properly, the advantages of passive and active damping controls are combined and made full use. Finally, the presented control scheme is simulated by the program of Matlab/Simulink, which shows that the LLCL filter with a hybrid damping control scheme can not only attenuate the harmonics around the switching frequency and reduce the inductance of the grid side, but also demonstrate its good filtering capability to guarantee the grid-connected current harmonics complied with the related standards.

Analysis on Fault Ride-Through Capability Enhancement by UPFC for Asynchronous Wind Turbine Generators

RAO Cheng-cheng, WANG Hai-yun, WU Han, ZHENG Hong, ZHOU Jing

2013, 46(8):  35-39.  DOI: 10.11930/j.issn.1004-9649.2013.8.35.4

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It is an inevitable trend to compensate the reactive power deficits in wind farms during system failures with dynamic reactive power compensation devices. In this paper, a system simulation model including unified power flow controllers (UPFCs) used for wind farm access study is established based on asynchronous wind turbine generator model and the principle and control strategy of UPFC The comparison of fault ride-through capability is executed between the wind farms installed with SVC and UPFC. The reasons for wind turbine over-speed in transient process are analyzed. Moreover, the voltage, power and speed of the asynchronous wind turbine generator before and after faults are also studied. The simulation shows that, compared with SVC, the response of UPFC is faster, therefore, by using UPFC as the reactive power source, the transient stability of wind farms can be enhanced further.

Profit Maximization Model for Energy Storage System in Microgrids Based on Dynamic Programming

WANG Lei, LI Na, ZENG Ming

2013, 46(8):  40-42.  DOI: 10.11930/j.issn.1004-9649.2013.8.40.2

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Energy storage systems play an important role in taking full advantage of renewable energy and improving the economic benefits of microgrids. Effective energy strategies need to be applied to realize the profit maximization. Considering the uncertainty and volatility of the electricity prices, the objective function of decision-making process is established, and the dynamic programming model to maximize the profits by energy storage systems is presented. The results show that the model can promote the development of energy storage technologies and provide greater profit margins. The impacts of price and energy storage strategy on the profits are analyzed by taking an energy storage system in microgrid as an example, and the feasibility and rationality of the proposed method are proven.

Case Study on Economic and Environmental Benefits of Grid-Connected Photovoltaic Systems

LIU Zhen-dong, ZHANG Shi-ding, JIA Han

2013, 46(8):  43-47.  DOI: 10.11930/j.issn.1004-9649.2013.8.43.4

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Taking the 20-kW grid-connected photovoltaic system(PV) with quasi-monocrystalline silicon modules for example, the social economic and environmental benefits of photovoltaic applications are calculated based on a benefit analysis model. The results show that the investment and energy recovery periods are 14 years and 2.9 years with one employment position provided on condition that the daily standard radiation hours are 4.14 h, the PV module costs 5.5 Yuan/W, the electricity price is 0.6 Yuan /kWh at the user side and there is no taxation. Compared with coal-fired generation, the emission reduction volume of the PV generation is 496.39 equivalent per year; the environmental cost of the PV power is 0.18 Fen/ kW·h; and the annual return on investment is 2%. The PV instantaneous power is proportional to the solar radiation volume and the environmental temperature. The weak correlation between the system power and the temperature is observed with the correlation coefficient equal to 0.46, while the correlation between the power and humidity turns out to be weak negative with the coefficient correlation of -0.38.

Smoothing Control of Grid-Connected Wind Power by VRB-Based Energy Storage Systems

LIU Xiang-xiang, WANG Ben, ZHANG Xiang, MA Ming-zhi

2013, 46(8):  48-53.  DOI: 10.11930/j.issn.1004-9649.2013.8.48.5

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In order to smooth the output of wind farms, a vanadium redox flow battery (VRB) based energy storage system (ESS) is equipped at the grid bus, in which a bi-directional AC/DC converter is used as the power regulator with the transient mathematic model derived in the synchronous rotating d-q coordinate system. Considering the characteristics of strong coupling and nonlinearity of the mathematic model, the linear transformation is conducted on the model with the state feedback exact linearization method. Then, the variable exponent reaching law of the variable structure control is used to design the close-loop controllers of the linear system. The simulation results indicate that the VRB-based energy storage system can smooth the fluctuation of wind farm outputs through fast charge and discharge process when the wind speed changes rapidly. And compared with the PI control, the variable structure controller shows better dynamic performance. In addition, the independent adjustability of active and reactive power of the VRB-based energy storage system can decouple the wind power control.

Discussion on the Post-Evalution Method Step of Wind Farm Generation

WANG Rui, JI Hai-sheng, LOU Hui-ying, ZHU Rui-zhao, LI Hong-xiu, JIAO Jiao

2013, 46(8):  54-58.  DOI: 10.11930/j.issn.1004-9649.2013.8.54.4

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Wind turbine generating capacity indicator is one of the important indicators reflecting the post-evaluation process of wind farm operator. Wind energy randomly changed, which principally influences the power generation in wind farm. The situation of wind could not be given an exact prediction. Therefore, it is really difficult to evaluate the generation quantity depending on wind. In this article, confronting this problem, the solution could be demonstrated that the actual generation quantity of operating wind farm would be calibrated with the representative year, and theoretical generation could be evaluated.By contrasting wind farm operation with result of feasible research, and adjusting accurately the electricity generation on operation period with representative year. It can be analyzed and summarized the practical effects on generation by some factors, according to the present situation of wind farm, it can be offered some advisements to resist these adverse influences, after the adjustment generating capacity more tally with the actual situation, as references for next feasibility research designing.

Application of Losing Partial Capacity Lithium Batteries of Parallel Operation in Energy Storage System

LIN Shao-bo, HAN Min-xiao, SUN Hai, LUO Chao

2013, 46(8):  59-63.  DOI: 10.11930/j.issn.1004-9649.2013.8.59.4

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Power lithium batteries, which are replaced from electric vehicle, can be called losing partial capacity lithium batteries and be used in energy storage system with restraining fluctuant power in distribution network after being screened and grouped, but their capacities and charge-discharge efficiency become lower because of internal resistance being larger. So a method of losing partial capacity lithium Batteries of parallel operation based on double loops of voltage and current is proposed according to internal resistance characteristic and external characteristic of power Li-battery of losing partial capacity. Charge-discharge efficiency of losing partial capacity lithium batteries can be improved and better accuracy of power tracking can be obtained in the case of restraining fluctuant power. The results of simulations and experiments demonstrate that charge-discharge efficiency of losing partial capacity lithium batteries of parallel operation and accuracy of restraining fluctuant power can be improved, and the feasibility of the proposed method are validated.

Decoupled Control Strategy of Active and Aeactive Power Based on Variable Structure Theory for Wind Power Double-Fed Induction Generator

DING Gui-li, WANG Ben

2013, 46(8):  64-69.  DOI: 10.11930/j.issn.1004-9649.2013.8.64.5

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In traditional vector control of double-fed induction generators (DFIGs), voltage cross-coupling compensation caused by counter- electromotive force of the rotor side makes the active and reactive power of the system cannot be decoupled completely. Moreover, traditional vector control relies on parameters of DFIGs heavily, which makes its control performances sensitive to the parameter variations and external disturbances. So, the exact linearization theory of decoupling control method is applied, which can reflect the time-variation strong-coupling characteristics of the high-order nonlinear system more accurately. In addition, taking account of the operation environment of the uncontrolled and strongly random wind speed, which makes the adjustment process of the traditional PI controller excessively lag behind and affect the dynamic-response performances, the sliding mode variable structure control theory is applied to design the controller with good dynamic-response and robustness against outside interferences and parameter uncertainties. The simulation results show that the proposed decoupling control method can make the controller achieve complete-decoupling and robust control of the active and reactive power with good dynamic-performance.

Application of Cathode Materials for Lithium-Ion Batteries in Electric Energy Storage

SU Wei, ZHONG Guo-bin, WEI Zeng-fu

2013, 46(8):  70-73.  DOI: 10.11930/j.issn.1004-9649.2013.8.70.3

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In view of the application of lithium-ion batteries in electrical energy storage systems, three kinds of main cathode materials of lithium-ion batteries, i.e. rock-salt LiCoO₂, spinel-type LiMn₂O₄ and olivine-type LiFePO₄ are studied in the aspects of their electrochemical and security performance as well as their costs. The existing problems and application prospects of different types of lithium-ion batteries in electrical energy storage systems are revealed, which concludes that LiMn₂O₄ and LiFePO₄ are right choices for power-type and energy-type applications, respectively.

An Approach to Evaluate the Capacity Benefits and Energy Benefits of Wind Farms Based on Probabilistic Product Simulation

ZHANG Bing-liang, ZHANG Bo-yi, WU Yao-wu, LI Jian-xiang, SUN Yong

2013, 46(8):  74-79.  DOI: 10.11930/j.issn.1004-9649.2013.8.74.5

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The benefits of wind farms to the power system can be summarized in two aspects: capacity benefits and energy benefits. The basic principles of probabilistic product simulation are introduced first. A wind farm is convoluted to modify the equivalent load duration curve as a multi-state generator, and an approach to evaluate the capacity benefits of wind farms based on the reliability index is proposed. The energy benefits included carbon emission trading are calculated based on the simulation results. The data of IEEE RTS-96 and NREL are taken as an example, the capacity benefits and energy benefits of wind farms are calculated and the influencing factors, such as penetration, wind regime, load profile and reliability level, are also studied.

Study on the Wind-Solar Storage Smart Emergency Power System

YAN Zhi-yong, HU Yi-gang, LI Zhi-jiu

2013, 46(8):  80-83.  DOI: 10.11930/j.issn.1004-9649.2013.8.80.3

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The emergency power system is widely used as an AC backup power source for various kinds of first-class and especially important power load. Meanwhile, the wind-solar hybrid power system is the best configuration for energy use and the mode with energy storage has the best advantages in the future. A smart emergency power system with wind-solar storage is developed and an emergency power system of wind-solar hybrid with energy storage is studied by using the static transfer switch as a switch equipment to realize. This equipment can control charge and discharge process of energy storage and intelligently judge the output signal to switch rapidly.

Combined Operation Analysis of Hydropower and Wind Power

XIN Song-xu

2013, 46(8):  85-89.  DOI: 10.11930/j.issn.1004-9649.2013.8.85.4

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Along with the rapid development of wind power in China in recent years, wind discarding problem is becoming increasingly serious. Further improving the regulating capacity of existing power systems is therefore needed. Combined operation of hydropower and wind power is one of the effective measures in the near future. In this paper, the intraday and inter-day output characteristics of wind power were introduced. On the basis of an analysis of the basis for combined operation of hydropower and wind power in terms of seasonal features and regulation speed, the combined operation principles of wind power and hydropower, and the benefits for promoting wind power accommodation and enhancing the efficiency of thermal power were studied. In order to compare the differences, two cases were designed. In one case the hydropower and wind power operated jointly, and in another case they operated separately. The differences of the two cases were analyzed in terms of wind power accommodation, coal consumption per kWh, thermal power start & stop cost, and the total fuel consumption. The results verified the benefits of the combined operation.

Generation Technology

Optimization of Engineering Design for 1 000-MW Units

ZHANG Yi, CAI Yuan-zong, SHI Ya-min

2013, 46(8):  90-94.  DOI: 10.11930/j.issn.1004-9649.2013.8.90.4

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Many optimized solutions have been applied in the design of two 1 000-MW units of Guodian Jianbi Power Plant to improve the plant’s operation economics and achieve the goal of energy-saving and emission-reduction. These solutions have made certain breakthroughs in the traditional design philosophy and operation model, which are valuable even for other projects. The main optimized solutions are listed as follows. First, the domestically-manufactured DCS is adopted in the units. Second, the floated steel shell well sinking scheme is used to build the circulating water pump house. Third, the four-pump-in-one-unit configuration is deployed in the circulating water pump system. Fourth, the land occupation of the plant is the least among those with 1 000-MW capacity units. Finally, the old and new coal storage areas are integrated and the treatment to the main building foundation is optimized. Since the unit commissioning, the performance indices of the power plant have reached the international advanced level with some technologies and indices even at the leading edge internationally.

Calculation of Moment of Inertia for Turbine Rotors Based on FCB Tests

ZHANG Le-tian, ZHOU Bin, CAO Chao

2013, 46(8):  95-97.  DOI: 10.11930/j.issn.1004-9649.2013.8.95.2

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The moment of inertia of turbine rotor is mainly measured and obtained from the computing of load-rejection tests. Now that the fast cut back (FCB) tests are carried out in many power plants which can also be applied for the assessment of the dynamic characteristics of steam turbine control systems, most of the plants would like to do the FCB test only while the objective of load-rejection tests reached as well due to the harmful effect of destructive FCB tests or regular load-rejection tests on the steam turbine rotors. So far, there has been no method proposed for calculating the rotor moment of inertia by FCB tests. In this paper, the regular method to calculate the moment of inertia based on load-rejection tests is explained and then the new method based on FCB tests is proposed. The comparisons between the two methods are conducted afterwards, which indicates that the difference between the two computing results is as low as 1.29%. In conclusion, the method based on FCB tests is qualified substitute for load-rejection tests.

Study on Simplified Nonlinear Model of 600-MW Supercritical Units

LIU You-kuan, LIU Chang-liang, ZHAO Yong-hui

2013, 46(8):  98-104.  DOI: 10.11930/j.issn.1004-9649.2013.8.98.6

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So far, in most studies, the supercritical unit is simply modeled in the form of transfer function matrix, from which the dynamic characteristics of other internal parameters cannot be observed. In this paper, the simplified nonlinear model of a 600-MW supercritical unit is established with the combination of mechanism analysis and parameter identification method. The dynamic and static parameters of the model are determined based on the data obtained from load variation test of one 600-MW“W” flame supercritical once-through boiler unit. Comparison between the Simulink simulation results and actual operation curves shows that the new model reflects the nonlinear dynamic characteristics of the unit well and can be used to study the coordinated control strategy and dynamic characteristic analysis for the supercritical units with “W” flame furnace. By modifying some parameters, the model can be used for research on other related aspects of supercritical units as well.

Study and Optimization on Thermal Load Logic of Unit Plants

ZHENG Wei, ZHAO Meng

2013, 46(8):  105-107.  DOI: 10.11930/j.issn.1004-9649.2013.8.105.2

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The 300-MW coal-fired unit plant in a cogeneration power plant is taken as an example to show the components of a unit plant. The workflow and main monitoring/control parameters of heat supply networks are also introduced. By analyzing the inaccuracy in heating steam flow measuring in heat load logic and its impact on the coordinated control system, an updated scheme on heat load logic calculation is proposed, including the heat load changing rate and its upper and lower limits. The new logic works well and the overall performance of the unit plant keeps stable after the heat supply network being put into operation. The security and economics of the unit plant get improved.

Power System

Selection Method of Intermittent Arc-grounding Fault Based on an Adaptive Notch Filter

ZHANG Zhi-xia, ZHANG Xin-yu

2013, 46(8):  108-111.  DOI: 10.11930/j.issn.1004-9649.2013.8.108.3

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Single phase-to-ground fault-detection for distribution system has been a challenge for many years, but the research has been mainly concentrated on permanent grounding fault, which is not general. Actually, the unstable arc-grounding and intermittent arc-grounding faults, which are kind of non-permanent grounding faults, are most likely to occur in the power system. When non-permanent arc-grounding fault happens, many high frequency components will be produced correspondingly. An adaptive notch filter (ANF) algorithm is introduced in this paper to extract the fifth harmonics signal of zero-sequence current . The algorithm can track the change of signal automatically by adjusting its own parameters. Thus it can accurately extract the real-time fifth harmonics signal. Empirical results show that the proposed method can find the fault feeder correctly when non-permanent grounding fault occurs. The principle is simple and reliable.

Identification of Voltage Sags Source Based on Hilbert-Huang Transform and Wavelet Packet Energy Spectrum

QI Bo, ZOU Jin-hui, FAN Yu-gang, SHAO Zong-kai, WANG Xiao-dong, HUANG Guo-yong

2013, 46(8):  112-117.  DOI: 10.11930/j.issn.1004-9649.2013.8.112.5

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For the identification of voltage sags source, a method based on HHT and wavelet packet energy spectrum is proposed. Firstly, signals of voltage sags are decomposed by EMD to get the IMFs, then each IMF is decomposed by n-layer wavelet packet to calculate it’s energy spectrum, and the HH spectrum is acquired by HT. The voltage sags source will be identified through comparing such characteristics as mutation point, amplitude, and harmonic. The final result of this simulation proves that the method is simple and reliable, with high recognition accuracy and practicability.

Analysis of the Impact of Power Consumption Structure Change on Transmission Line Loss

SHANG Lei, WANG Jin-feng, YANG Li-xi, LOU Bei, SHI Hui-jun, YANG Jin-feng

2013, 46(8):  118-122.  DOI: 10.11930/j.issn.1004-9649.2013.8.118.4

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For quantitative analysis of the impact of different components of power consumption structure on transmission losses, the trend of transmission loss caused by power consumption structure change was evaluated and a calculation method of transmission loss of different types of load representing daily load curves was proposed based on the marginal loss coefficient method. The relationship between different types of load and transmission line loss rate was given through qualitative analysis of the maximum load utilization hours. A case study of a city’s power system proves the feasibility of the presented method and the correctness of the conclusions.

On-Line Monitoring System for Insulator Salt Density Based on Optical Fiber Sensing Technology and Its Application

LUO Dong-song, HUANG Jing-mei

2013, 46(8):  123-127.  DOI: 10.11930/j.issn.1004-9649.2013.8.123.4

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The optical field distribution theory of optical waveguide was introduced based on the feasibility study of the optical fiber sensor to measure the external insulation pollution degree of the transmission and transformation power equipment. The light energy parameters of quartz glass used as the optical sensor was analyzed by spectral data analysis algorithm and the corresponding relationship between luminous flux attenuation and salt density was set up. Subsequently the optical sensor Pollution Monitoring System was developed to realize the on-line monitoring of insulator salt density. The system has already been applied in Tianshui 330 kV transmission line and the results are satisfied. The test results indicate that the system can timely and accurately monitor the salt density of the transmission and distribution equipment, and guide the production department to clean the transmission and distribution equipment in order to avoid excessive or insufficient maintenance.

Study on Measurement of Three-Phase Asymmetric Loads Based on Parameter Identification

QIU Shu-min, YANG Hao, YIN Jia-min, OU Yong, LUO Jian

2013, 46(8):  128-132.  DOI: 10.11930/j.issn.1004-9649.2013.8.128.4

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Taking the three-phase four-wire system as an example, the impact of asymmetric loads on electric energy measurement is studied. In this paper a new method to improve the electric load measurement based on virtual neutral point voltage parameter identification is proposed, that is, under unknown load parameters at the consumer side, the virtual neutral point voltage is identified with the voltage and current waveforms sampled synchronously at the point of common coupling of three-phase load, so as to accurately measure and compute the value of three-phase loads. Through the simulation using Matlab, the electric power measurement values with traditional method and parameter identification method are compared respectively regarding the actual load consumption values, which verifies the accuracy and reasonableness of the proposed method.

Unbalanced Control Scheme for Cascade STATCOM Based on SBPF

CAO Yang, QIU Le-bing, TANG Jian-yu, LIN Li, XU Wan-liang

2013, 46(8):  138-142.  DOI: 10.11930/j.issn.1004-9649.2013.8.138.4

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Under unbalanced system voltages, the operation of cascade static synchronous compensator(STATCOM) shall be maintained in stable state so as to make contribution to power factor correction and voltage stability. However, the performance of a cascade STATCOM with traditional decoupling power control will drastically deteriorate under unbalanced voltages. Therefore, a novel control scheme for star-connected cascade STATCOM operating under voltage unbalance is proposed, in which the selective band pass filter (SBPF) is combined with decoupling power control to realize unbalanced control and rapid response characteristic of STATCOM. Simulation results show that the control scheme can significantly improve the operation stability and compensation effect of the cascade STATCOM under unbalanced voltages compared with the traditional decoupling power control algorithm.

Smart Grid

Optimal Location of Urban Electric Vehicle Charging Stations Using a Two-Step Method

GAO Ya-jing, GUO Yan-dong, LI Tian-tian

2013, 46(8):  143-147.  DOI: 10.11930/j.issn.1004-9649.2013.8.143.4

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Considering the characteristics of site location for urban electric vehicle(EV) charging stations, a two-step locating method is proposed in this paper. In the first step, based on the analysis of the charging demand for various road sections, the planning area is searched by using immune algorithm to find out the candidate sections. In the second step, the comparison between the candidate sites in different candidate sections is performed by taking account of factors such as geographical feature and distribution networks, which are quantified by virtue of fuzzy analytic hierarchy process. Through comprehensive evaluation the optimal sites can thus be determined.

Research of Implementation Plan for Advanced Applications in Smart Substations

HAN Ben-Shuai, SHI Pin, SUN Zhong-wei, LI Yan-li, SHU Na, ZHANG Hang

2013, 46(8):  148-152.  DOI: 10.11930/j.issn.1004-9649.2013.8.148.4

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As the major feature of smart substations, the advanced applications can effectively reduce the operation and maintenance costs, enhance the equipment reliability and prolong the equipment lifetime as well as improve the reliability, stability and economy of system operation. Aiming at the existing problems and development status of the advanced applications in smart substation, the multi-stage implementation plan and corresponding objectives of each stage are put forward, which can provide helpful reference for the implementation of advanced application in smart substation.

Analysis and Study on Intelligent Substation Process Level Network Data Stream

XU Chun-xia, ZHANG Yan-xia, GE Yue-tian

2013, 46(8):  153-159.  DOI: 10.11930/j.issn.1004-9649.2013.8.153.6

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On the basis of a feasibility study of the common network transmission of the main data SMV, GOOSE and PTP1588 message of intelligent substation process level network, the star topology is considered to be the optimal scheme for process layer network. Through comparison of two packet filtering technologies, VLAN and GMRP and by taking the typical substation D2-1 in IEC 61850 as an example, a set of interval-based VLAN logic structure classification schemes were proposed, and a detail description and computation was made of common the existing data flow, communication delay and delay shaking. Finally, the data flow delay of the common network transmission was simulated with software OPNET, which demonstrated the feasibility of the common network transmission by VLAN technology..