Table of Content

20 January 2017, Volume 50 Issue 1

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Special Column for Power Planning

China’s Power System Development and Operation: Main Challenges and Countermeasures

ZHANG Yunzhou, SHAN Baoguo

2017, 50(1):  2-6.  DOI: 10.11930/j.issn.1004-9649.2017.01.002.05

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In the period of 13th Five-Year(2016-2020) and the forthcoming future, China’s economy will be in a stage of“New Normal”. During this period, the energy supply-demand balance will experience a fundamental change, the institutions and mechanisms of marketization will become more and more perfect, and the development of China’s power industry will face new challenges. Based on the circumstance that the electricity supply will keep ample, the percentage of renewable generation will continue to rise and the market- oriented reforms will achieve breakthrough in the coming decades, this paper discusses the main problems encountered in the development and operation of power system and make a analysis of their causes in terms of the uncertainty of electricity supply-demand relation, the function of coal-fired power generation, integration of renewable energy, security and stability of power system, and electricity market operation. Finally some practical countermeasures are proposed.

Analysis on the Development Ideas of Electric Power Industry in the Period of the 13th Five-Year

LIU Shiyu, DU Zhongming, WANG Qian, ZHOU Tianrui

2017, 50(1):  7-12.  DOI: 10.11930/j.issn.1004-9649.2017.01.007.06

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As the kernal of energy industry, electric power is an important basic industry of national economy. The sustainable and healthy development of electric power industry is critical for energy revolution, transforming and upgrading of traditional industries, the national economic and social development as well as the people’s livelihood,and even the national security. Based on a review of the development history of China’s power industry, this paper focuses on the existing major problems and their causes in China’s power industry, and analyzes the present situation and challenges faced by China’s power industry in the field of economic development, energy supply and environment protection in the period of 13th Five-Year(2016-2020) and medium-to-long term. On this basis, the paper proposes and expounds the basic ideas for power industry development in the period of 13th Five-Year, including“green and clean development”, “coordinated and optimal development”, “flexible intelligence” and “marketization” development.

Research on Power Grid Development in the Period of “13th Five-Year”

HAN Feng, SONG Fulong, LUO Jinshan, HAN Xiaonan

2017, 50(1):  13-18.  DOI: 10.11930/j.issn.1004-9649.2017.01.013.06

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Based on the 13th Five-Year Power Development Plan(2016-2020) issued by the State Energy Administration, the paper analyzes the status quo and problems of existing power grid in China, studies the prospect and requirement of future power grid development, and discusses the idea and focus of backbone power grid development in the period of“13th Five-Year Planning”. It is necessary to optimize in due time the layout of synchronous power grid for meeting the requirement of large-scale development of renewable energy, to speed up the upgrading of backbone power grid for meeting the security needs of large-scale multi-infeed HVDC system, and to optimize the structure of the main power grid for coordinated development of power grids of all voltage levels. It is proposed to accelerate construction of strong key power grids in the period of“13th Five-Year Planning” in order to promote the intensive development of the large-scale hydropower and renewable energy bases and to achieve the optimal allocation of energy resources in the national scope.

Analysis on the China’s Electricity Demand Growth under the New Economic Norm

SHAN Baoguo, SUN Xiangdong, LI Jiangtao, WANG Xiang, MA Ding

2017, 50(1):  19-24.  DOI: 10.11930/j.issn.1004-9649.2017.01.019.06

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China’s economy is in a stage of “New Norm”, under which the economic growth rate, industrial structure and driving forces for development are now experiencing fundamental changes. It is of great strategic importance to analyze the economic development trends and new features of power industry under the “New Norm”. Considering the structural reform of supply-side and the factor of demand-side, the overall economic growth of China will be characterized by a“L” type downward slope in the period of 13th Five-Year Plan (2016-2020) and 2021-2030. The electricity consumption growth will slow further. It is expected that the total electricity consumption of the whole society will reach 7-7.6 trillion kW·h and 9.1-11 trillion kW·h in 2020 and 2030, respectively. In terms of structure, the electricity consumption of third industry and residents will become the main driving force for electricity consumption growth of the whole society. In terms of regions, the proportion of electricity consumption in the western region will increase, but the eastern region will still be the country’s load center in the future.

Reflections on Implementation of the 13th Five-Year Distribution Network Planning

WU Zhili, WANG Xuyang

2017, 50(1):  25-29.  DOI: 10.11930/j.issn.1004-9649.2017.01.025.05

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In the period of 13^th Five-Year Plan(2016-2020), the implementation of the distribution network planning has attracted nationwide concern given the new situation of the intelligent upgrade of distribution network, the sale side reform of electricity and transformation of the electricity consumption. Based on an analysis of the new challenges in implementation of the 13th Five-Year distribution network planning, some countermeasures are put forward on the effects of uncertainties and it is proposed to pay attention to the coordinated planning implementation, including construction of the closed-loop management system of planning implementation, and continuous advancing the transformation of planning implementation to optimal allocation of resources by means of information processing, standardized construction and enhancing benefit analysis.

Analysis on New Energy Development Based on the 13th Five-Year Electric Power Planning

LI Qionghui, WANG Caixia

2017, 50(1):  30-36.  DOI: 10.11930/j.issn.1004-9649.2017.01.030.07

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On November 7^th, 2016, the National Development and Reform Commission and State Energy Administration officially issued the“13th Five-Year(2016-2020) Power Development Planning”. According to the goals and key tasks set by the planning, and based on the history of new energy development and related statistics, an analysis is made on the scale, speed, layout and market consumption of new energy development during the 13th Five-Year period, and several planning issues related to high percentage new energy are discussed. The results show that, during the 13th Five-Year period, the growth rate of installed capacity of new energy will decrease, but the newly installed capacity of new energy will keep stable. And the development layout of new energy is expected to be adjusted significantly, which depends on whether the distributed development of new energy can make a breakthrough. Three measures are proposed to solve the integration problems of new energy, including adjusting the construction pace of new energy in the regions that already have serious integration problems, increasing the flexibility and adaptability of the power system, and orderly facilitating trans-provincial new energy consumption.

The Security and Stability Problems of Large-Scale Outbound Power Transmission of Renewable Energy in the 13th Five-Year Power Plan

GAO Chao, GUO Qiang, ZHOU Qinyong, SHI Haobo, QIN Qin

2017, 50(1):  37-42.  DOI: 10.11930/j.issn.1004-9649.2017.01.037.06

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During the 13th Five-Year period(2016-2020), the Chinese government is promoting long-distance and large-capacity power transmission projects and the UHV power grids have witnessed very fast development. The UHV transmission projects Zhalute in North East China to Shandong and Shengli to Ximeng in North China are important transmission channels mentioned in“13th Five-Year Plan of Electrical Power development”. The planned future power grid will be characterized by large-scale collected power sources delivered outbound by DC transmission, large-scale accession of renewable energy and co-operation of AC and DC grids. The enhanced transmission capacity of DC will bring new challenges and problems to the security and stability of power grid. Assisted by the State Grid Simulation Center, a transient security assessment is made for large-scale power transmission of UHVDC, and an analysis is made on a series of new problems brought about by large-scale outbound power transmission. Possible countermeasures are provided to effectively solve the main security and stability problems brought about by the large-scale outbound power transmission planned in the 13th Five-Year planning.

Analysis on the Domestic Manufacture of AP 1 000 Nuclear Reactor

WANG Yingrong, ZHENG Zheng

2017, 50(1):  43-48.  DOI: 10.11930/j.issn.1004-9649.2017.01.043.06

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As the third generation nuclear reactor in the world, the AP1000 reactor was introduced to China in 2006. Through ten years of efforts, it is basically realized to design and apply the AP1000 reactor to engineering as marked by the commissioning of the first reactor unit in 2016. Based on the national strategy of developing clean energy and manufacture industry in the 13th Five-Year Planning period (2016-2020), the paper systematically introduces the domestic manufacturing of the key equipment of AP1000 reactor unit, and analyzes the problems arising from the domestic manufacture and the direction of research, which will provide a support for perfecting the localized equipment supply chain of the AP1000 reactor units.

Analysis on the Load Following Prospect of Nuclear Power in China in the Period of “13th Five-Year”

ZHENG Kuan, WANG Yiyu, WANG Yaohua, GE Rui, GUAN Li, ZHANG Fuqiang, ZHANG Jinfang, LIU Chang, WANG Shen

2017, 50(1):  49-55.  DOI: 10.11930/j.issn.1004-9649.2017.01.049.07

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With the rapid development of nuclear power in China, more clean energy is supplied for the development of the economy and society, while more pressure is brought about on the peak regulation of power grid in the context of slowing power demand in China. On the basis of analyzing the load following capability and operation experiences of the nuclear power plants in different countries and regions, an analysis is made on the safety and economy of the nuclear power plants in participating in the peak regulation of power grid. Through a comparative analysis of the unit types, operation principle, technical standards and other aspects of nuclear power plants between China and other countries such as France, etc., a study is made on the feasibility of nuclear power plants to participate in the peak regulation of power grid in China, and related suggestions is proposed.

Power System

Research and Application of Jing-Jin-Tang Frequency Regulation Resource Decision Support System in Competitive Mechanism

CHANG Li, SHI Peiran, SU Feng, LIU Jun, SI Xiaofeng

2017, 50(1):  56-61.  DOI: 10.11930/j.issn.1004-9649.2017.01.056.06

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Jing-Jin-Tang power grid has long been through the command scheduling method for the frequency regulation resource by the need to call. Regulation price is not accurate to reflect market price determined by supply and demand. Based on current situation and problems of frequency regulation service in Jing-Jin-Tang power grid, a competitive operation mechanism and mode is designed. Using “centralized bidding, marginal clearing” as the core, the proposed mode realizes decision support system of frequency modulation in competitive market environment. Actual calculation example shows that proposed system can significantly reduce frequency regulation cost and improve resource utilization level.

Study on DC Bus Voltage Deviation Control Autonomy in Hybrid AC/DC Micro-Grid

WU Bingxin, XIE Weihua, YE Hongen

2017, 50(1):  62-66.  DOI: 10.11930/j.issn.1004-9649.2017.01.062.05

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DC bus voltage stability control is very important for hybrid AC/DC micro-grid. A practical and efficient control method is proposed for DC bus voltage deviation stability control autonomy of hybrid AC/DC micro-grid. In grid-connected mode, the droop control method of DC bus voltage under idle mode is used to control the DC bus voltage stability through AC-DC inverter, which can avoid frequent charge-discharge. In islanding mode, the DC bus voltage is controlled by DC-DC converter. For reliability of system in islanding mode, the DC bus can connect multipath DC-DC stored batteries. The distributed energy utilization ratio is improved through autonomous stability control, and the service life of electronic devices are increased under idle mode. Experimental tests prove that the proposed method has good control efficiency and can provide a good technical support for the rapid development of hybrid AC/DC micro-grid.

Design of Distributed Damping Controller in Smart Grid

SHENG Lijian, SUN Jun, WANG Hailong, FU Rong, YONG Taiyou

2017, 50(1):  67-73.  DOI: 10.11930/j.issn.1004-9649.2017.01.067.07

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With the support of wide area measurement system(WAMS), the smart grid can effectively control the stable operation of power grid through interaction of information. For the low frequency oscillation problem of wide area interconnected power system in smart grid, this paper proposes a distributed wide area damping controller by taking advantage of the flexibility of distributed control, which only uses the measurements from local and adjacent nodes as the input signals. The new graph theory is adopted to describe the communication topology of the controller’s input signals. By taking into account of the transmission delay of remote signals, the controller is designed under the sufficient condition of time-delay dependent stability. Finally, a simulation comparison is made on a four-machine two-area system, which shows that the designed controller can effectively improve the system damping and enhance the stability of system.

Harmonic Compensation Optimization Dispatch Method Based on Multiple APFs for Distribution Line

LIU Yun, CHENG Wenxin, JI Xiaopeng

2017, 50(1):  74-78.  DOI: 10.11930/j.issn.1004-9649.2017.01.074.05

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An optimization dispatch method for harmonic compensation in distribution feeders using multiple APFs is proposed to suppress harmonic voltage propagation. The phenomenon of harmonic voltage propagation along distribution feeder is analyzed by using the transmission line theory, and a control strategy for APF-based harmonic compensation is provided. An optimization dispatch model of harmonic compensation is established and the single objective genetic algorithm is used to optimize the harmonic compensation parameters of inverters. The simulation results show that the proposed algorithm can optimize the harmonic compensation parameters and reduce the total harmonic distortion of node voltages to rated values.

Modeling Method for Process-Level Network in Smart Substation Based on OPNET

LING Guang, WANG Zhiliang, LV Jianlong, HE Qiang

2017, 50(1):  79-84.  DOI: 10.11930/j.issn.1004-9649.2017.01.079.06

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The accomplishment of some time-critical application in smart substation, such as relay protection, is determined by the performance of process-level network. An OPNET based modeling method for process-level network is proposed in order to evaluate network reliability and real time characteristic quantitatively. According to device structure, packet classification and flow characteristic, models of different kinds of intelligent electronic device(IED) including merging unit, intelligent terminal and protection device are built. Then model of each bay is created based on IED model. Model of process-level network is also established using star topology group method. Finally, study of Virtual Local Area Network is conducted on the established platform. Simulation and testing results demonstrate validity of proposed model.

Practical Expert System for Transformer Fault Diagnosis Based on Multi-Dimensional Information Fusion Technology

XU Yang, XIE Tianxi, ZHOU Zhicheng, LU Yuncai, LI Jiansheng, CAO Jian, JIANG Chao

2017, 50(1):  85-91.  DOI: 10.11930/j.issn.1004-9649.2017.01.085.07

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Due to the complex structure of the power transformer, the fault diagnosis is more and more dependent on the fusion of a large amount of information. Therefore, a practical expert system for power transformer fault diagnosis based on multi-dimensional information fusion technology is proposed in this paper. First, the structure of the multi-dimensional information fusion model is analyzed, and then the method of factor analysis is proposed to calculate the information fusion weights. Based on the fusion technology, the practical expert system for transformer fault diagnosis is built, which is finally verified by an example of 110 kV main transformer. Moreover, the recognition, selection and excavation of the multidimensional data are analyzed. With the advantage of simple logic, high reliability, and fast diagnosis, the proposed expert system can be embedded in intelligent terminals to provide intelligent expert diagnosis for the staff on-site.

Research on Harmonic Transfer Characteristics of Transformer

JIA Jingran, DUAN Xiaobo, LU Jinling, ZHOU Wen, REN Rui

2017, 50(1):  92-96.  DOI: 10.11930/j.issn.1004-9649.2017.01.092.05

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The harmonic equivalent model of transformer is established base on T type equivalent circuit of transformer with consideration of distributed capacitance effects. Thorough analysis and calculation of its harmonic transfer characteristics are performed. The result shows that in no-load or light load condition, the harmonic is linear transferred in transformer. In other cases harmonic components change significantly across transformer. Matlab software is used to analyze harmonic transfer characteristics of transformer under different load conditions. Experiments performed on actual transformer show consistency with theoretical analysis and simulation results.

Genration Technology

The Analysis of Thermal Stress Control Technology for Ultra-Supercritical Steam Turbine

WANG Zhijie, CHEN Houtao, ZHU Xiaoxing, FU Qiang

2017, 50(1):  97-100.  DOI: 10.11930/j.issn.1004-9649.2017.01.097.04

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The technology of thermal stress control had been introduced into controlling the ultra-supercritical steam turbine by Shanghai Turbine Company(STC), which makes its can automatically optimizing between quickness and reducing the loss of life of turbines in the process of start-up and variable operation conditions. In this paper, the principle, implementation and monitoring methods were introduced in detail of the thermal stress control for the ultra-supercritical steam turbine, and some problems which had been posed due to the thermal stress limit were described in the process of debugging and commissioning in this type unit, which have certain guiding significance for debugging, operating and maintenance for this type turbines.

Analysis and Treatment of Shaft Sealing Problems in 1 000-MW Double Reheat Turbines

XUE Jiangtao, ZHANG Yaohua, MA Yunxiang, DING Jianliang

2017, 50(1):  101-104.  DOI: 10.11930/j.issn.1004-9649.2017.01.101.04

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The successful commissioning of Taizhou No.3 unit indicates the start of the commercial operation of the million kilowatt coal- fired generating units with the double reheat system. While the operating parameters appear good, the unit has yet some problems such as low gland seal steam temperature during debugging, low shaft seal steam pressure, large shaft seal steam temperature, pressure fluctuations after tripping, and high VHP exhaust steam temperature due to sealing steam reversed flow. Aiming at these problems, detailed analysis is conducted, which concludes that they are attributed to the high exhaust steam temperature, the large shaft seal steam leakage, the dreadful atomization effect of shaft seal attempering water, the shaft seal steam temperature control logics inconsistency with the double reheat system and the lack of check valve on the outlet pipe from the first shaft seal of the VHP cylinder. Following the analysis, corresponding solutions are put forward, including installing electric heaters, improving the atomization nozzle, modifying the temperature control logics and equipping check valves, hoping to help better operating the same and similar units in the future.

The Key Factors in Turbine Governor System Influencing the Low Frequency Oscillations in Power System

ZHANG Bao, FAN Yinlong, GU Zhenghao, WU Wenjian

2017, 50(1):  105-110.  DOI: 10.11930/j.issn.1004-9649.2017.01.105.06

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The steam turbine governing system is closely related to the power grid security, of which there are several factors that can specifically affect the low frequency oscillation of power systems. In combination with detailed case studies, the mechanism of the impacts from these factors are presented in the aspects of the steam turbine control function, the PID parameters, the DEH side power control loop, the frequency modulation circuit, the time delay of the control system, the valve opening shaking and the signal fluctuation, etc. In addition, the operation procedures and equipment defects which possibly cause the low-frequency oscillation are put forward for improving the operation stability level of power grids.

Research on Bently 3500 Signal Distortion in the TSI System of 300-MW Power Generation Units

JIANG Liewei

2017, 50(1):  111-115.  DOI: 10.11930/j.issn.1004-9649.2017.01.111.05

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Aiming at the fault of frequent bearing vibration signal interruption in a 300-MW power generation unit, through the analysis on bearing current and voltage testing, vibration signal detection and control loop testing, it is verified that a clear interference signal is added to the bearing vibration signal through the cables or the network due to the ill TSI system grounding, which makes the working voltage of the eddy current sensor exceed the normal range (-2.75~-16.75 V), causing the card staying at NOT OK status and the bearing vibration signal being interrupted. Therefore, the TSI grounding network is reconstructed. Since the completion and application of the network no abnormal bearing vibration signals have ever appeared. Thus, the unit security has been greatly improved.

Design and Application of the Simulation on an Integrated Platform

CUI Qingru, NIU Haiming

2017, 50(1):  116-120.  DOI: 10.11930/j.issn.1004-9649.2017.01.116.05

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In this paper, the concept of integrated platform is first proposed. Then, through the analysis on the pros and cons of three simulators currently used in thermal power plants, a new simulator based on the integrated platform architecture is presented. Taking the DCS platform as the development core, the simulator adopts the object-oriented programming method and modular way to make it a subfield of the platform, which can realize the functions such as operation and thermal control personnel training, real-time simulation and thermal economic analysis. The results of practical operation have proved the feasibility of the fully incentive simulator design based on the integrated platform.

Study on Intellectualized Pressure Drop Coefficient Calculation for LHSI Pump in PWR Nuclear Power Plants

YAN Mingjing, ZHAI Bajing, DAI Yapei

2017, 50(1):  121-124.  DOI: 10.11930/j.issn.1004-9649.2017.01.121.04

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In order to ensure the data synchronization, the measurement parameters are acquired from transmitters instead of local temporary instruments, and then computed in the control system to obtain the pressure drop coefficient at the intake of LHSI pump. In addition, using the known LHSI pump flow and head under RWST condition, the pump flow and head of the sump suction condition are derived according to the deduction model and the usable NPSHa is calculated conservatively by utilizing the pressure drop between the sump and the pump suction. The research of intelligent calculation on pressure drop coefficient at LHSI pump intake has been successfully applied in smart power stations, which can provide important original input with accurate and credible data for the study on LHSI pump safe operation in the event of the LOCA in nuclear power plants.

Failure Analysis of a Valve Clack under Impact Load with Finite Element Method

DENG Linghui, KANG Yujun, WANG Junmin, CHENG Yongming, WANG Bining

2017, 50(1):  125-129.  DOI: 10.11930/j.issn.1004-9649.2017.01.125.05

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Through establishing the three-dimension model of a valve clack in a nuclear power station ventilation system, the stress changes of the valve clack under impact loads in the process of bumping the valve frame are simulated with the finite element method. The finite element analysis results from the comparison of four different working conditions show that, due to the unreasonable structure of the valve plate, the bending compression stress of the channel steel flange edge above the pin hole is higher than the material plastic extension strength when the valve plate is opened; when the valve plate is closed, the opposite direction stress and deformation will be produced in the same place. During the long operating process, the valve plate repeatedly hits the valve frame and high low-cycle fatigue stress happens in the channel steel flange edge above the pin hole, which leads to the fatigue damage of the channel steel flange until its rupture. Improvement needs to be made on the valve plate structure to prevent the fracture failure of the valve clack.

New Energy

Dynamics Load Optimization and Simulation Analysis of Wind Turbine under Independent Pitch Control

JIA Wenqiang, XIE Shuangyi, HE Jiao, CHEN Xingjie, JIN Xin, CHEN Jia

2017, 50(1):  130-135.  DOI: 10.11930/j.issn.1004-9649.2017.01.130.06

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In order to solve the uneven dynamic load problem of large-capacity wind turbines, the Linear Quadratic Gaussian (LQG) scheme is proposed, which can calculate and compare the loads borne by main components of wind turbine under different control modes based on the wind turbine model and LQG controller through co-simulation of SIMPACK and Simulink software. The simulation result shows that, compared with the collect pitch control strategy, the independent pitch control strategy is superior in stabilizing the output power and load fluctuation. Compared with the PI collect pitch control, the LQG independent pitch control can better reduce the fatigue load of main components of wind turbine.

Wind Power Accommodation Capacity Evaluation Model Based on Complex Network

WANG Jingfei

2017, 50(1):  136-139.  DOI: 10.11930/j.issn.1004-9649.2017.01.136.04

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Traditional wind power accommodation capacity evaluation methods only focus on power grid energy consumption without consideration of other affecting factors which leads to poor performance. An accommodation capacity evaluation model is proposed based on complex network analysis. The evaluation flowchart is introduced. Based on current operation point, the high limit and low limit of wind power accommodation amount is obtained. The evaluation object function is constructed according to the range shaped by limits. Various aspects, including power network stability constraints, unit output constraint and wind output constraint, are evaluated. Wind power accommodation capacity under specific time period in complex power network are then performed. The experimental results show high practical value of proposed method.

Wind Power Probability Prediction Based on t Location-Scale Distrabution

YANG Mao, DU Gang

2017, 50(1):  140-145.  DOI: 10.11930/j.issn.1004-9649.2017.01.140.06

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Wind power forecasting is difficult because of its stochastic variance characteristic. Based on t location-scale distribution function, a wind power forecasting method is proposed. The t location-scale function is adopted to describe probabilistic distribution of wind power prediction error. The prediction is then performed based on the distribution model. The coverage rate and average bandwidth are selected to evaluate prediction accuracy. The historic data of power fluctuation of a wind farm in Jinlin province proves the effectiveness of proposed method.

Research on Fuzzy Control of PV Pumping System Based on Switched Reluctance Motor

ZHENG Guo, ZHENG Wanxin

2017, 50(1):  146-150.  DOI: 10.11930/j.issn.1004-9649.2017.01.146.05

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A photovoltaic(PV) pumping system and corresponding control method with fuzzy controlled maximum power point tracing (MPPT) and rotor speed control of 6/4 switched reluctance motor(SRM) is proposed. Based on control strategy of whole system, mathematic model of PV array is analyzed, and mechatronic model of SRM is built. Then simulation model of PV pumping system is built in the MATLAB/Simulink. Simulation and experiment results reveal that proposed algorithm can realize stable tracing of PV array maximum power. Curves of flux linkage and current of each phase show stable SRM operation, which verify the feasibility of proposed PV pumping system and fuzzy controller.

Ratio Between Energy Storage and Intermittent DG Capacity with a Practical Storage Capacity Estimation Method

YANG Fenyan, CHEN Xiaoke, HUANG Jiajian, LI Lanfang, ZHANG Zequn, XIAO Jun, DONG Lei, ZOU Guangyu

2017, 50(1):  151-157.  DOI: 10.11930/j.issn.1004-9649.2017.01.151.07

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As the increasing development of DG penetration in distribution network, the impact brought by DG’s characteristics of intermittency and volatility is more obvious. Energy storage system(ESS) is the key solution to this problem. However, the ratio of energy storage and DG capacity is not very clear in current research. An estimation method is proposed based on spectral analysis. Firstly, the calculation approach of ESS capacity based on filtering is introduced. Secondly, based on experiment data, the relationships of the biggest fluctuation and ESS rated power, the ESS rated power and ESS rated energy capacity are analyzed. Because of the difficulty in real project, DG rated power is used to calculate the biggest fluctuation power. Hence the ratio of DG rated power and ESS capacity can be obtained by easy calculation instead of complex energy storage optimization method. In the end, the comparison of results obtained from ESS capacity optimization and proposed practical method on typical engineering cases proves simplicity and effectiveness of proposed method.

Coordinated Control Strategy for Hybrid Energy Storage System Based on State of Charge

LI Hui, HUNANG Yaomei, MA Fei

2017, 50(1):  158-163.  DOI: 10.11930/j.issn.1004-9649.2017.01.158.06

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In order to optimize the operation status of hybrid energy storage system, a novel hierarchical coordinated control strategy is proposed, which consists of the upper layer energy management and the lower layer hybrid energy storage control. Based on the micro-grid bus voltage, frequency and the state of charge(SOC) of hybrid energy storage system, the upper layer energy management uses the fuzzy logic algorithm to optimize the charging and discharging power of hybrid energy storage system so as to keep the SOC of energy storage devices within a reasonable range. Based on the low-pass filter and the SOC of lithium iron phosphate battery & supercapacitor, the lower layer hybrid energy storage control establishes the power allocation correction algorithm to optimize the SOC of energy storage system. The simulation results indicate that the proposed hierarchical coordination control algorithm can effectively reduce the SOC’s variation range of hybrid energy storage system and avoid the over charging or over discharging.

Information and communications

Comparative Study on Desulfurization Wastewater Sludge Dewatering

YE Zhian, HAN Lin, GUO Pengfei, SUN Lijao, WANG Dongmei, WEI Changming

2017, 50(1):  164-167.  DOI: 10.11930/j.issn.1004-9649.2017.01.164.04

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As the final stage of the FGD wastewater treatment and discharge process in the power plant, sludge dewatering may affect the whole wastewater processing system operation if it is not designed reasonably or operated properly. There are two kinds of sludge dewatering devices, the frame filter press machine and the centrifugal dewatering machine. In a power plant, the centrifugal dewatering machine is originally adopted in the desulfurization wastewater sludge treatment and the produced cake contains more than 80% of water and presents semi-fluid state, causing secondary pollution in the process of loading/unloading and transportation. Therefore, the dewatering system is modified by replacing the original dewatering centrifuge with the frame filter and installing the sludge buffer tank, sludge circulation pump and sludge feed pump. The comparative study on the dewatering devices before and after the modification is conducted. The study results show that the frame filter is more suitable for the desulfurization wastewater sludge treatment process. The mass fraction of the dewatered cake solid is higher than 30%, and the operation of the system is stable with lower energy consumption.

Test and Study on Performance of Wet FGD Coordinated Particulate Matter Control for Ultra-Low Pollutants Emission

ZHU Jie, XU Yueyang, JIANG An, MO Hua

2017, 50(1):  168-172.  DOI: 10.11930/j.issn.1004-9649.2017.01.168.05

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The test results of the particulate matters after flue gas desulphurization are analyzed for some ultra-low pollutants emission power plants. It is discovered that the performances of wet FGD coordinated particulate matter controls vary quite significantly. The particle removal efficiency of non-empty tower with efficient demister such as bundle and roof types, are substantially higher than the empty tower with common demisters. The test results show that the performance of collaborative particulate matter controls is greatly affected by the performance of demisters and the components with gas-liquid mass transfer enhancement. Using the wet FGD can achieve effective collaborative control of particulate matters.

Research and Application of Low-Low Temperature Electrostatic Precipitator Combined with MEEP

ZHAO Haibao, HE Yuzhong, WANG Xianming

2017, 50(1):  173-176.  DOI: 10.11930/j.issn.1004-9649.2017.01.173.04

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As a new combinatorial dust removal technique, the low-low temperature electrostatic precipitator(LLT-EP) has the defect of dust re-entrainment, so the mobile electrode electrostatic precipitator(MEEP) needs to be used together to ensure high dust removal efficiency. In this paper, the study on the technical characteristics, structure and mechanism of LLT-ESP+MEEP is carried out with some typical domestic and foreign cases being introduced and analyzed. Practices show that the LLT-ESP+MEEP technique is one of the technical combinations to achieve the ultra-low emission. Its outlet dust concentration can get lower than 15 mg/m³, meeting the ultra-low dust emission requirements of below 10 mg/m³ or even below 5 mg/m³ when the desulfurization system is integrated.

Research on Flue Gas Heater for Urea Pyrolysis of SCR Flue Gas De-NOx System

XU Wei

2017, 50(1):  177-180.  DOI: 10.11930/j.issn.1004-9649.2017.01.177.04

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In the SCR(Selective Catalytic Reduction, SCR) denitrification system adopting urea as the reducing agent, the power consumption of the electric heater in front of the pyrolysis furnace is high. In order to reduce the power consumption, in the technical retrofit of the 640-MW unit in a power plant, the electric heater is modified as a bypass system, a high temperature flue gas heater is installed and the high temperature flue gas is used to heat the hot primary air. The high temperature flue gas, of which the temperature is about 650 ℃ and the flow is about 6 000 m3/h under standard state, is induced from the horizontal flue between the high temperature and the low temperature reheaters. The technical route is analyzed, and the retrofit effect is verified by variable load tests. The data analysis shows that the technical route is feasible and easy to implement, also the system runs well. Therefore, the high temperature flue gas heater can completely replace the electric heater reducing the house service rate and power supply costs.

Impact Analysis of Boiler De-NO_x System on High Back Pressure Heat Supply Units

XU Junzhao

2017, 50(1):  181-184.  DOI: 10.11930/j.issn.1004-9649.2017.01.181.04

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In recent years, all boilers for civic heat supply units have been equipped with flue gas denitrification device due to the increasingly severe consequences of environmental pollutions. However, the operation of the flue gas denitrification device has exhibited some side effects on the high pressure heat supply system. In this paper, through the analysis on the thermodynamic properties of the heat supply system, it is concluded that the boiler minimum denitrification load is the major factor restricting the high pressure heating system economic operation. As a result the retrofit plan is proposed to fully take advantage of denitrification device for high back pressure heating unit under all loading conditions of. The case analysis of a 135-MW such unit indicates that the net coal consumption rate will be reduced by 8.67 g/(kW·h) once the plan is implemented. In this way the potential of energy saving in high back pressure steam turbines can be further explored.