Table of Content

10 September 2016, Volume 49 Issue 9

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Special Contribution

Discussion on Whether Coal Electricity Production Is Overcapacity in China

ZHANG Jingjie, WANG Zhixuan

2016, 49(9):  1-6.  DOI: 10.11930/j.issn.1004-9649.2016.09.001.06

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From the viewpoint of the significant change on the contradiction of power supply and demand in China’s“new normal”, the characteristics of development on both the power supply and demand sides in recent years are analyzed. The analysis on whether the coal power production is overcapacity is conducted, from the aspects of the“quantity” and “quality”; the values of different bodies; the market mechanism and the comparison between different countries. It concludes that the power load structural adjustment, the insufficient total power demands, the large power structure changes, the increase of peak regulation duties on coal-fired units, the continuous coal price drops, as well as the good economic efficiencies of coal power are all reasons of coal power surplus. Based on the analysis, some production capacity limitation measures are proposed, such as the new power production capacity should be limited from both the demand and supply sides; the coal power functional transformation should be promoted; the potential of existing coal power generation units should be fully taken advantage of; the peak regulation capability of coal-fired power generation units should be enhanced; the excessive substitution of large units for small ones should be avoided; the demand side should wait for the recovery of power demand; the demand for electricity should be enlarged actively and the carbon market should be established to suppress the coal electricity production capability. In addition, with the optimization of energy system, 10% of coal power equipment utilization rates can be further taken advantage of potentially. The energy production capability of 300 million tons of raw coal is available during the 13th Five-Year Plan Period.

Cause Analysis on Wind and Photovoltaic Energy Curtailment and Prospect Research in China

ZHOU Qiang, WANG Ningbo, RAN Liang, SHEN Huiyun, LV Qingquan, WANG Mingsong

2016, 49(9):  7-12.  DOI: 10.11930/j.issn.1004-9649.2016.09.007.06

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With the China’s economy entering into the new normal state characterized by high speed development, the abandoned wind and photovoltaic power problem is becoming increasingly prominent. Firstly this paper reviews the development process of wind power and photovoltaic power from 2004 to 2014, and then summarizes the current status in China. Based on the authoritative data released by the National Energy Bureau, the average rate of abandoned wind power rate and the total abandoned wind power are calculated dated from 2011 to 2015 in China. The data of abandoned photovoltaic power in 2015 are also provided. Secondly five reasons are presented which contribute to the high abandoned new energy power rate in China. The paper also explores the prospects of China’s new energy short-term and long-term development. Finally, two major factors and four dilemmas significantly impacting the development of new energy in China are put forward.

Power System

Determination of Suitable Locations for Power System Stabilizers

WU Fuxia, WANG Jinjian, PAN Jiajun, YIN Yibo, LIN Jianming, WANG Jun, CAO Rui

2016, 49(9):  13-17.  DOI: 10.11930/j.issn.1004-9649.2016.09.013.05

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Power System Stabilizer (PSS) in power system is a closed-loop controller. However, the traditional participation factor method for configuration location selection only considers controllability and observability of PSS input signal. It may give misleading results under heavy load condition. A composite participation factor method is proposed to identify the most effective location selection of generating units to be equipped with power system stabilizers, which takes into account both controllability, observability of input signal and feedback control effect of power system stabilizer. The case study with a two-area, four-generator system confirms that the proposed method can provide more effective location for power system stabilizer especially under heavy load condition, which is more effective than traditional participation factor method.

Optimal Power Flow with Hybrid HVDC Transmission Based on Weighted Predictor-Corrector Interior-Point Method

LIN Zijie, HUANG Weimin, WEI Zhinong, SUN Guoqiang, SUN Yonghui

2016, 49(9):  18-22.  DOI: 10.11930/j.issn.1004-9649.2016.09.018.05

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In solving hybrid HVDC system optimal power flow(OPF) problem, predictor-corrector interior-point method may cause over-correcting divergence. A weighted predictor-corrector interior-point method is proposed to solve diverge problem in this case. This algorithm retains predictor step of predictor-corrector interior-point method and selects corrector direction in total proportion of Newton direction dynamically. The numerical simulation result indicates hybrid HVDC system can operate in better optimization point. The accuracy and effectiveness of proposed method are demonstrated on multiple IEEE test systems.

Ultraviolet Detection Technology of 750 kV Resistant to Porcelain Insulator Based on Artificial Pollution Test

CAI Jing, ZHANG Nan, MA Zhong, PENG Min, SHANG Xiaoguang, JIA Zhidong, WANG Linjun

2016, 49(9):  23-29.  DOI: 10.11930/j.issn.1004-9649.2016.09.023.07

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Timely and effective testing of insulators is essential to safe operation of 750 kV transmission line. As a fast and efficient method to detect insulator discharge, ultraviolet detection technique is very important in insulator detection. Ultraviolet detection result of the 750 kV Porcelain Insulator by using artificial pollution test is analyzed first. Two characteristic quantity indexes, fluctuation range of photon number and mean value of spot area, are proposed to evaluate discharge severity. Both indexes can effectively evaluate degree of insulator discharge. The testing results are of great significance to application of UV detection technology in 750 kV insulator testing.

Windage Yaw Characteristics of 110 kV Transmission Lines Based on Conductor-Insulator Coupling Model

YUAN Li, GU Xiangke, WAN Shuting, LIU Feng

2016, 49(9):  30-34.  DOI: 10.11930/j.issn.1004-9649.2016.09.030.05

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The average elevation of Geermu City, Qinghai Province is more than 3 000 meters. 110 kV Chahanluo-Geermu line have windage yaw flashover accidents throughout the years. In order to study reasons of frequent accidents in windage yaw flashover of overhead transmission line, the coupling model of conductor-insulator is established. The stochastic turbulent wind field with average 30 m/s wind speed is simulated by MATLAB. Insulator transient response analysis under stochastic wind velocity field is also performed by ANSYS. Simulation results show that suspension insulators have large probability of wind age yaw flashover under the lightning overvoltage and higher priority during line rebuilding process.

Online Detection Technology of Solid Insulation RMU Based on Infrared Thermal Imaging

YE Hairong, GE Leyi, ZHONG Guiying

2016, 49(9):  35-40.  DOI: 10.11930/j.issn.1004-9649.2016.09.035.06

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Large thermal power in high voltage insulation unit often leads to serious local heat and short circuit fault. In order to ensure distribution power grid stability, security and reliability, a novel on-line detection technology is proposed for solid insulation ring main unit(RMU). Firstly, the original infrared thermal image is obtained and transmitted to distribution automation system master station by using different communication modes including 230 Mesh and fiber. The image is analyzed after preprocessing, noise filtering, image enhancement, and edge detection to detect fault in solid insulated RMU. This novel technology can diagnose electrical joints accurately comparing to traditional contact measurement method.

Experimental Study on Surface Flashover of PMMA Driven by DC Voltage at Atmospheric Pressure

WANG Tao, XU Yuqin, ZHAO Yimin, HU Zhiliang, ZHAO Beibei, XIE Qing, WANG Chuan

2016, 49(9):  41-45.  DOI: 10.11930/j.issn.1004-9649.2016.09.041.05

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In order to study the phenomenon of surface flashover and its influence on the insulation material under DC condition, surface discharge experiments on PMMA surface are carried out with different electrode distances. The surface morphology, contact angle and surface composition of material are analyzed. The results show that lilac corona occurs near electrodes during discharge process. Flashover arc fluctuation and intensity increase with discharge distance. Discharge mark is formed between electrodes after discharge. The mark is more obvious at locations closer to cathode side. Material surface becomes muddy with increase number of discharge. Roughness is increased, and water contact angle decreases too. After discharge, C1s content is decreased, however O1s content is increased. A large number of C-C bonds are broken to generate C-O bond, O-C=O bond and other hydrophilic groups which increase material hydrophilicity. The analysis of this paper shows that the surface micro topography and surface elements have a certain influence on the flashover voltage, and it has a certain guiding significance to improve the flashover voltage.

VSC Model-Free Adaptive Controller in AC and DC Distribution Network

LIU Xuliang, ZHU Huanli

2016, 49(9):  46-50.  DOI: 10.11930/j.issn.1004-9649.2016.09.046.05

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Characteristics of urban power supply system are analyzed. With improvement on IEEE-13 distribution system, a distribution system model is designed to improve system supply reliability and power quality. In order to prevent multi-terminal HVDC system instability caused by faults on AC end, a model-free adaptive control(MFAC) technology is proposed. When AC system fault occurs, traditional PID controller has bad performance due to large system parameter disturbance. The DSC inverter controller based on MFAC technology discards need of detailed control system model without losing control capability. Simulation results under different abnormal operating conditions verify feasibility and effectiveness of proposed design.

Optimal Sitting and Sizing of DGs Based on Improved Ant Colony Algorithm

WANG Zongli, LI Ming, CHEN Jian, WANG Zhuang, LI Qin, HUANG Xiaoping

2016, 49(9):  51-55.  DOI: 10.11930/j.issn.1004-9649.2016.09.051.05

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In order to maximize economic benefit and minimize pollution, an improved ant colony algorithm is presented for optimally sitting and sizing of DGs in distribution network. Firstly, a comprehensive model for distribution network operation, which includes various distribution generations under different environments, is established. The operation and power constraints are discussed. Secondly, an improved ant colony algorithm is proposed to improve convergence speed and precision by adding a pheromone constraint. Then, the process of optimally sitting and sizing of DGs is described. Finally, the proposed method is implemented in MATLAB to optimize sizing and sitting of a medium-voltage distribution network. The feasibility of proposed algorithm is validated through comparison of relevant cases.

Research and Development of Practical Application Platform

Research and Implementation of Simulation Model and Algorithm of Multi-terminal VSC-HVDC Transmission System in SG-OSS DTS

WEI Wenhui, ZHOU Shujin, CHEN Zhengping, ZHAO Yunjun, LI Guodong, JIN Yiding, XIA Jihong

2016, 49(9):  56-61.  DOI: 10.11930/j.issn.1004-9649.2016.09.056.06

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Based on SG-OSS DTS(Smart Grid Operation Support System-Dispatcher Training Simulator), the overall design of VSC-HVDC (Voltage Source Converter) simulation is presented. Steady-state simulation model of multi-terminal VSC-HVDC and hybrid solution algorithm of AC/DC system are discussed, and an alternating solution algorithm based on Newton-Raphson method is proposed. Finally, simulation results prove validity and effectiveness of proposed model and algorithm. The method has been applied to electric power dispatching and control center of Fujian Province. Application results show that dispatcher training system with VSC-HVDC can build a high fidelity training simulation platform for electric power dispatch and operation. It meets training, exercise and evaluation needs of electric power dispatching and control center.

Substation Simulating and Training System Based on Quest3D

WANG Dahu, GAO Huizheng, CHEN Xia

2016, 49(9):  62-65.  DOI: 10.11930/j.issn.1004-9649.2016.09.062.04

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Current substation simulation and training system often has problems including long development cycle, development and maintenance difficulty. A new simulation training system based on Quest3D is developed. An 110 kV substation is selected as simulation object. Firstly, 3DMAX is used to establish substation primary equipment model. Then, the model is imported into Quest3D software. By using extensive Channel provided in Quest3D, a complete substation training system is built. The system includes functions of automatic roaming, manual roaming, equipment inspection, weather simulation, animation, navigation and communication. The system development does not require complex programming techniques and has advantages of low development cost, short cycle, high training efficiency and easy maintenance. The three-dimensional animation and interactive training method can help students quickly learn necessary abilities including substation main wiring, equipment working principle, field operation and accident response.

Application of EtherCAT in Modern Power Electronic Equipments

JIANG Yingwei, HOU Kai, CHEN Yonghua, LUO Jian

2016, 49(9):  66-71.  DOI: 10.11930/j.issn.1004-9649.2016.09.066.06

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With smart grid development in our country, power electronics are widely used in power systems Modular Multilevel Converter (MMC) technology is major approach in current high voltage large capacity power electronic equipment. However, traditional centralized architecture of control system needs improvement. With performance analysis of EtherCAT on realtime,synchronism and flexibility, a distributed control system architecture based on EtherCAT Bus-technology is proposed. A test platform which include nine H-bridge modular is constructed. Experiment performance demonstrates excellent distributed control system behavior. Many key technologies in EtheCAT application are summarized based on practical experiences. The proposed distributed architecture is also capable for other kinds of multi voltage level power electronic equipment.

Design of Intelligent Electrical Terminal Containing Electrical Credit Evaluation

YANG Wenhai, ZHU Jing, GAO Yajing, CHENG Huaxin, XUE Fushen, WANG Jingmin

2016, 49(9):  72-77.  DOI: 10.11930/j.issn.1004-9649.2016.09.072.06

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With the emergence of smart grids and rapid development of demand side management, a design of intelligent electrical terminal containing intelligent electrical credit evaluation is proposed. In this design, grid can not only transmit valuable electric information to users effectively and timely, but also receive user feedbacks. Based on data collected by intelligent electrical terminal, electrical credit evaluation is capable of evaluating user habits quantitatively. The results can be used to conduct and standardize user behavior and provide significant reference to system planning, operation and dispatching.

A Quick Identify Method for Electricity Business Based on AC Algorithm

WANG Hongkai, LIN Liangcheng, WANG Jian, YU Minzhu, ZHOU Huan

2016, 49(9):  78-82.  DOI: 10.11930/j.issn.1004-9649.2016.09.078.05

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Most business systems in electric power company use mobile terminals to access internal electricity information network, and signatures of protocols are used to identify different businesses while exchanging data between internal and external network. In order to solve problems of slow pattern matching and large memory consumption, a quick electricity business identify method based on AC algorithm is proposed. After analyzing security access procedure in electricity information network, protocol features of high-density traffic and security gateway performance bottlenecks, the proposed method groups signatures of protocols according to the transport layer protocols for parallel processing to increase matching throughput. The bitmap-based storage is selected to reduce memory consumption of rules library. At last, simulation results show that proposed method can increase matching throughput and reduce memory consumption.

Study and Application of Safety Evaluation Platform for Region, Province, Prefecture and County Integrated Power Grid Dispatching

CHEN Rongzhi, QU Pu, XIN Kuo, ZHANG Nan, LIAO Bingbing, ZHENG Quanchao

2016, 49(9):  83-86.  DOI: 10.11930/j.issn.1004-9649.2016.09.083.04

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Southern Power Grid Dispatching Institutions continues to perform scheduling business safety evaluation for years. However, different evaluation criterion, statistical method and evaluation process in various units, as well as lack of evaluation data centralization, causes lots of problems including unclear responsibility, incommensurability evaluation results, low efficiency and insufficient data statistical analysis. Southern Power Grid Dispatching Center proposed to build an integrated safety evaluation platform including scheduling business network for regioned, provincial, prefecture and county level. The target is to realize closed loop control mechanism of safety evaluation. Through a unified evaluation standard, process, inspection statistical method and standardized data interface, Southern Power Grid achieves multiple goals including entire network evaluation data centralization, gradual automatic evaluation and real-time tracking evaluation process. This system can ensure authenticity of evaluation work and satisfy dynamic and visualization control requirements in different levels. The proposed system has ability to improve production safety management level of scheduling system continuously.

Generation Technology

Analysis on the Abnormal Operation of High-Pressure Bypass System of 1 000-MW Ultra-Supercritical Units

LIU Lei, ZHANG Qiusheng, WU Zhigang, WANG Fuqiang, ZHANG Jinying

2016, 49(9):  87-92.  DOI: 10.11930/j.issn.1004-9649.2016.09.087.06

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In order to improve the reliability of the 100% high-pressure bypass system of 1 000-MW ultra-supercritical units, the variation trends and characteristics of major parameters are analyzed and summarized after the misoperation of a pressure switch in the high-pressure bypass system of a power plant. On the premise of no changes to the original design and protection principles, the optimized thermal control strategies are proposed. By adopting the proposed strategies, the overall security of the unit is improved. These optimized control strategies have been popularized and applied to the 1 000-MW units of the same type, and the effectiveness has been proved.

Analysis and Improvement of Speed Governor Model Considering the Main Steam Pressure Influences

GU Zhenghao, BAO Jinsong, ZHANG Bao, DINGYangjun, HU Zhou

2016, 49(9):  93-98.  DOI: 10.11930/j.issn.1004-9649.2016.09.093.06

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In order to meet the requirements for primary frequency regulation capacity of thermal power plants in power grids, the study on speed governor modeling of coal-fired power generation units is conducted. Aiming at the problems existing in the PSD-BPA models with no considerations on the main steam pressure due to the incompleteness of the models, by analyzing the influences of main steam pressure on the primary frequency regulation capacity of steam turbines under the sliding pressure operation condition, the improved GK and TB models are proposed and verified through simulation. In addition, the concept of pressure margin is proposed, which suggests that the operation pressure should be 12% higher than that at full valve opening when the primary frequency regulation capacity reaching as much as 6% of the rated load.

Analysis on Condensate Piping Vibration of 330-MW Direct Air-Cooling System

JIN Hongwei, LI Chao, LIU Xue, HUANG Saidong, MAO Xueping

2016, 49(9):  99-103.  DOI: 10.11930/j.issn.1004-9649.2016.09.099.05

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The condensate pipeline vibration has great impacts on the safe operation of direct air-cooling units. The condensate pipeline system of a 330 MW direct air cooling power plant continuously vibrates during the operation. To remove the vibrations, the vibrational modes of the condensate pipeline system are calculated on the ANSYS Workbench simulation work platform. The simulation results show that the vibrations of the piping system are influenced by the condensate cavitation and water flow impact. Therefore, the structure of condensate water downcomer is optimized by changing the flow characteristics in tubes. Also, the transient dynamics analysis is applied to the pipe models before and after the optimization. In addition, by comparing the acceleration time curves and the changes of dynamic pressure and total pressure at Extraction Point A before and after the optimization, the optimization effects are evaluated as well.

Thermal Economics Comparison Between High Back Pressure Heating and Extraction Heating for a Direct Air-Cooled Power Unit

YU Yao

2016, 49(9):  104-108.  DOI: 10.11930/j.issn.1004-9649.2016.09.104.05

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Direct air-cooled power generation units can supply heat adopting the high back pressure heating scheme or the extraction heating scheme. In this paper, the analysis model is established to compare the thermal economic performance of the two schemes. Through calculation, the energy utilization efficiencies of the two heating schemes for a 330 MW unit are compared under constant main steam flow rate or constant power output with the back pressure of 34 kPa for high back pressure heating and that of 10 kPa for extraction heating at various water supply temperatures and heating loads. The results indicate that the high back pressure heating scheme shows higher energy utilization efficiency than the extraction heating scheme with the heating loads increasing at the water supply temperatures not higher than 70 ℃. With the water supply temperature rising, part of steam has to be extracted from the intermediate pressure cylinder outlet for the high back pressure heating scheme, which lowers the economic performance. The higher the water supply temperature, the fewer advantages in energy saving are shown in the high back pressure heating scheme. When the heating loads are low, part of the electrical loads can be shifted from the high back pressure heating unit to another unit if permitted.

Development and Application of PDMS-Based 3D Analysis Tool for Non-destructive Testing

JIANG Weifeng, ZHANG Wei

2016, 49(9):  109-113.  DOI: 10.11930/j.issn.1004-9649.2016.09.109.05

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In the fields of nuclear and thermal power generation, as well as the chemical industry, etc., pipe welding defects are often difficult to be detected due to the reachability of the inspecting tools. Therefore, it is of great importance to solve this problem during the design stage. Based on the 3D design platform, a design tool for pipe welding non-destructive testing(NDT) is developed for nuclear power plants. The tool, which combines the NDT related parameters and space demand in 3D environment, realizes the reachability simulation and the automatic generation of inspection list for welding NDT, therefore, improves the design quality and efficiency substantially. The proposed methodology, i.e., 3D simulation of NDT space demand, which, for the first time, integrates the welding NDT demands into 3D layout design in pre-construction phase, can eliminate the risk due to inspection reachability.

Technology and Economics

Regional Differences and Non-equilibrium Relationship Between Energy, Economy and Environment in China

XU Yang, HE Yongxiu

2016, 49(9):  114-118.  DOI: 10.11930/j.issn.1004-9649.2016.09.114.05

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It was found that a long-run co-integration relationship exists from energy consumption to economic growth and unidirectional causality exists from energy consumption to carbon dioxide emissions. Specifically, when the energy consumption increases by 1% in the provinces of G, H and J, the economy will increase by 0.76%, 1.41% and 1.44%. When the relationship between economic growth and energy consumption deviates greatly from the long-term equilibrium, these three provinces will spontaneously return to equilibrium at the speed of 0.064, 0.039 and 0.240; when the opposite situation occurs, these numbers will be 0.042, 0.023 and 0.11. In the development stage of industrialization, the higher the rate of the secondary industry’s contribution is, the faster the return speed will be.

Monthly Operation Warning Model of Power Grid Corporation Based on Combination Weighting and Fan Radar Chart

ZHAO Huiru, LI Nana, XING Jinfeng

2016, 49(9):  119-124.  DOI: 10.11930/j.issn.1004-9649.2016.09.119.06

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In order to improve operation warning of power grid corporation, it is essential to analyze key operation indicators. The key factors affecting operation warning analysis are selected from operation monitoring system of power grid corporation. The combination weighting method is applied to determine index weights. An operational analysis warning model based on an improved fan radar chart is proposed, and four reference samples are introduced to intuitively reflect the warning level. Taking a provincial corporation as an example, the operational status between January and October in 2014 are analyzed in detail. The results verify feasibility of proposed method.

Dynamic Intraday Rolling Scheduling Considering Electricity Quantity Progress

WANG Yang, SU Feng, DENG Li, ZHANG Ben, SHI Peiran

2016, 49(9):  125-129.  DOI: 10.11930/j.issn.1004-9649.2016.09.125.05

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In response to difficulties brought by load variation, load fluctuation, maintenance schedule change of generation and transmission, the mode, model and method of intraday rolling scheduling considering electricity quantity progress constraint are proposed. Based on optimization algorithm, the proposed method can follow the progress of unit power plan accurately through controlling nonlinear balancing target of electricity quantity. This real time rolling mechanism can improve its adaptability to the operation circumstance of power grid, through following changes of both power grid and unit operation conditions, thus the unit electricity quantity plan can be completed accurately by optimizing quantity distribution across time and space dimensions.

The Impact of Wind Power Priority Dispatch on Power System Energy Intensity and Economic Cost

LIU Suwei, ZHAO Xiaoli, YAN Fengguang

2016, 49(9):  130-136.  DOI: 10.11930/j.issn.1004-9649.2016.09.130.07

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China’s wind power has developed quickly in recent years. However, the issue of wind power curtailment is becoming more and more seriously. One of reasons of China’s severe wind power curtailment is inconsistent recognition of social and economic value of wind power development. In order to analyze the value of wind power development, using Jing-Jin-Tang power network data in 2014, power system energy intensity and economic cost with different ratio of wind power integration is calculated. It is further analyzed that whether wind curtailment is necessary to minimize energy intensity and yielding point during wind curtailment occurrence. The results show that energy intensity decreases with wind power generation proportion increases. To minimize power system energy intensity, wind curtailment occurs at 14.19% and 19.92% wind power proportion in winter high load and low load, respectively. However, the wind curtailment rate is close to zero at those points. Furthermore, when the wind power proportion is 22.51% and 24.62% in winter high load and low load respectively, the wind curtailment rate is only about 5%. The economic cost of power system decreases with wind power proportion increases.

Demand Response Model of TOU Electricity Price Based on Data Mean and LSSVM Algorithm

LI Na, ZHANG Wenyue, WANG Yuwei, FU Jingshuai, WANG Weijie, WANG Lin

2016, 49(9):  137-141.  DOI: 10.11930/j.issn.1004-9649.2016.09.137.05

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In order to improve system robustness and meet demand of customers’ behavior rule under time-of-use (TOU) price, a simulation model is proposed. Firstly, with historical data equalization, the impact of non-price fluctuations in historical data on user’s demand response is removed. Secondly, training sample set data capacity is extended by establishment of equivalent TOU. Thirdly, a forecasting model is constructed by using LSSVM regression technique. Lastly, by using historical data of an industry in T area, the demand response curves of Peak, Flat and Valley Load under TOU are obtained to verify validity of proposed model.

New Energy

Research on Optimal Allocation of PV-Wind-Storage-Diesel Based on Two Layers of Coordinated Dispatch

WU Hongbin, ZHUANG Huaidong, ZHU Xinchao

2016, 49(9):  142-147.  DOI: 10.11930/j.issn.1004-9649.2016.09.142.06

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To solve deep battery discharge problem in microgrid constructed by photovoltaic(PV)-Wind-Storage-Diesel system, two layers of coordinated dispatch strategies is presented. In the first layer, diesel generators and hybrid energy storage system are coordinated dispatch with each other. The diesel generators starts before battery state of charge(SOC) reaches lower limit. In the second layer, the power of batteries and super capacitors are distributed based on dynamic characteristics of the hybrid energy storage system. Based on the coordinated dispatch strategies, optimization models of distribution generations (DGs) are constructed and an improved genetic algorithm is applied in optimal dispatch problem. Testing results with example system verifies the correctness and effectiveness of proposed models, algorithm and coordinated dispatch strategies.

Grid Optimization of Energy Storage Technology with Fluctuating Wind Power

WU Guocheng

2016, 49(9):  148-151.  DOI: 10.11930/j.issn.1004-9649.2016.09.148.04

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Large wind power grid connect has big shock to system due to fluctuations in wind power. An optimized energy storage method during wind power grid connect is discussed. By using time series method, samples of wind speed in different times are obtained first. A periodic wind speed forecasting model is then constructed based on neural network. The smooth wind power fluctuation cycle is calculated and energy storage is arranged according to the cycle. Test results show that the proposed method can smooth wind power grid connect and reduce shocking impact on the system.

Parallel Inverters Control Based on Dual Second-Order Generalized Integrators Virtual Impedance

PENG Chunhua, XIONG Xin, PAN Lei, HUANG Zhimin

2016, 49(9):  152-159.  DOI: 10.11930/j.issn.1004-9649.2016.09.152.08

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The virtual impedance control is widely employed in parallel inverters control. However, voltage drop introduced by controller is not desirable. Also, virtual impedance is usually implemented as time derivative of inverters output current, which makes system highly sensitive to output current noise and nonlinear loads. A dual second-order general-integrator(DSOGI) scheme is proposed for virtual impedance implementation, which avoids to perform the time derivation function and is less sensitive to the output current and nonlinear loads. The proposed scheme has ability to suppress output current noise, and reduce effect of nonlinear loads on the system. It can also reduce voltage drop and improve system power quality. Simulation on parallel inverters system control proves the effectiveness of DSOGI based virtual impedance.

Method and Software Development of Microgrid Capacity Configuration Based on Genetic Algorithm

NIU Tao, QIAN Kang, SUN Chunjun, XU Wenchao, WANG Zhenquan, ZHA Shensen

2016, 49(9):  160-164.  DOI: 10.11930/j.issn.1004-9649.2016.09.160.05

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The purpose of microgrid capacity configuration is to reduce operation cost while ensuring power supply reliability. With consideration of existing research and operating experience on DG(distributed generation), energy storage and microgrid, an optimal capacity configuration method is proposed, and a software DGPO(distributed generation planning and optimization) is developed. During optimization of grid-connected microgrid, constraints including transmission power, short-circuit current, voltage loss, voltage fluctuation are considered. Search space of genetic algorithm is optimized to ensure rationality of results. Different energy control strategies are formulated to improve algorithm generality for both isolated-island and grid-connected microgrid. The feasibility and effectiveness of proposed method is verified through a microgrid demonstration project in Jiangsu.

Post-Assessment of Wind Resource of a Wind Farm in Inner Mongolia Base on Contrast Analysis

GU Xinbo, LI Xinghua, WANG Jia, XU Lina

2016, 49(9):  165-169.  DOI: 10.11930/j.issn.1004-9649.2016.09.165.05

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A comprehensive post-assessment of a wind farm in Inner Mongolia is performed based on contrast analysis. The assessment aspects include average wind speed, wind direction frequency, maximum wind speed, wind speed frequency, hours of effective wind speed and variation of wind power concentration. By comparing assessment factors in two different stages, the research shows that annual average wind speed and average maximum wind speed of the weather station decrease. The decrease rates are -0.015 and -0.185 respectively. Predominant wind direction, which is SSE, stays same. The rate of calm wind is lower by 21.6 percent. The decrease of average wind speed is about 0.8 m/s. The wind speed decrease 10 percent during day and 12 percent during night. The hours of effective wind speed in three wind speed rang lowered 263 h, 533 h and 925 h. The peak wind speed frequency decrease from 6.5~7.5 m/s to 4.5~5.5 m/s. Wind power concentration and wind speed change are similar. In January, wind power concentration is similar to months of second half in the year. The decrease of wind power concentration is more obvious for other months excluding May. The peak wind speed area decrease from 14.5~16.5 m/s to 9.5~10.5 m/s.

Energy Conservation and Environmental Portection

Experimental Study on Integrated Compression, Desulfurization and Denitrification with Simulated Gas in Oxy-fuel Combustion

ZHAO Rui, LI Yanbing, CHEN Yinbiao, HUANG Weijun, YU Xuehai, SHI Xiaohong, CHEN Chuangshe

2016, 49(9):  170-174.  DOI: 10.11930/j.issn.1004-9649.2016.09.170.05

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Oxy-fuel combustion is one of the mainstream techniques of large-scale commercial CO₂ capture. In order to intensively study the performance of CO₂ capture, also the capability of the integrated desulfurization and denitrification in the compression process during oxy-fuel combustion, the liquid carbon dioxide is used to wash the mixed gas on the 50 kg/h test stand and related parameters are adjusted. It is showed that NO_x, SO_x and other pollutants can be removed in the compression process simultaneously. Furthermore, the test on the effect of liquid-gas ratio on NO_x and SO_x removal efficiencies is conducted. The results show that the total NO_x and SO_x removal efficiencies are both up to more than 98% with SO₂ contents less than 50×10^-6 and NO_x contents less than 30×10^-6 in the exhausted flue gas. The study concludes that the compression and purification process has the potential to achieve the integrated desulfurization and denitrification.

Practice of CO₂ Absorption Process in Natural Gas Power Plant

AN Hongguang, TONG Yiying, ZHAO Ying, LI Changzhu, HUANG Zhongyuan

2016, 49(9):  175-180.  DOI: 10.11930/j.issn.1004-9649.2016.09.175.06

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With choice of MEA and ionic liquid as absorbents for CO₂ capture of flue gas, practice of chemical absorption process system in natural gas power plant is described. The process parameters, operating results, energy consumption, cost increases and the impact on electricity and heat prices are analyzed and discussed.

Application of Pulse Enhancement and Rotary Electrode Technologies in Dust Removal Retrofit for Thermal Power Plants

REN Yan, KONG Chunlin, LIU Jie, ZHANG Weijie, LUO Binyi

2016, 49(9):  181-184.  DOI: 10.11930/j.issn.1004-9649.2016.09.181.04

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To harness the atmospheric pollution, the ultra-low emission requirements have been proposed in many domestic areas. In this paper, the study on pulse power supply, electrode configuration, gas distribution and rotatable brush dust cleaning technologies are conducted for reducing the outlet dust concentration of Electrostatic Precipitators (ESPs). The study concludes that the combination of pulse enhanced power combining with rotary electrode can improve the dust removal efficiency with superior advantage. Taking the dust removal retrofit project in a 330-MW unit of a power plan for example, the above applications are presented. The practice shows that the ESP dust emission mass concentration reaches as much as 16.4 mg/m³ after the modification, meeting the standard of 20 mg/m³ required by the “Emission standard of air pollutants for thermal power plants”. So far the ESP is still running in good condition, which lays good foundation for the ultra-low emission of the power plant.