Table of Content

20 April 2016, Volume 49 Issue 4

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Colume of Flue Gas Denitration

The Key Substances Causing SCR Denitration Catalyst Deactivation and the Preventive Measures

SHEN Yanmei, WEI Shuzhou, CUI Zhiyong

2016, 49(4):  1-5.  DOI: 10.11930/j.issn.1004-9649.2016.04.001.05

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The essential substances causing deactivation of SCR catalysts in coal fired power plant are summarized and classified. Based on the analysis, it is found that the submicron particles are multitudinous with small pore sizes in the flue gas. Those toxic substances are blamed for the cause of catalyst deactivation, such as alkali metals, alkaline-earth metals and heavy metals, which tend to deposit on the surface of the submicron particles. Therefore, when the submicron particles accumulate on the surface of the catalyst, the consequential poisoning and passage blocking then become the major cause of catalyst deactivation. Finally, the research and development of agglomeration technology and poisoning-resistant catalyst are introduced for deactivation alleviation.

Design and Application of 2 × 300 MW Units Urea SNCR Denitrification Engineering

LIANG Lei

2016, 49(4):  6-11.  DOI: 10.11930/j.issn.1004-9649.2016.04.006.06

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Taking the design of urea SNCR flue gas denitrification project for 2×300 MW units in a power plant in Xinjiang as an example, this paper presents in details the workflow process of major component units and related equipment and material selection of the urea SNCR flue gas denitrification system. It also introduces the fundamental basis of spray gun layout design and the system operation effects. Finally the investment and operation costs of the ammonia SNCR denitrification technology as well as the urea SNCR denitrification technology are analyzed. The operation practice results show that when the urea/NOx mole ratio is 0.5, and the original flue gas NOx concentration ranges between 178~187 mg/m3, the denitrification efficiency can be stabilized at more than 50% with the escape ammonia concentration of only 1.2~1.9 mg/m3, meeting the environmental protection standard and design requirement with .the escape ammonia concentration only 1.2~1.9 mg/m3.

Construction and Implementation of the Whole Process Management for SCR Denitration Catalyst

DU Zhen, YANG Liqiang, YAN Min, ZHANG Yang, HU Da, ZHU Yue

2016, 49(4):  12-16.  DOI: 10.11930/j.issn.1004-9649.2016.04.012.05

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To reduce the operation cost of SCR denitration system and ensure the system operation in good condition, this paper constructs the whole process management model for the SCR denitration catalysts. The management model covers the entire process of catalyst production, operation and deactivation, which includes factory surveillance, factory acceptance test, performance testing, life assessment, regeneration technique and so on. By means of catalytic performance testing, the real time performance of the catalyst from production to operation can be mastered and the assessment and treatment can be conducted timely whenever abnormalities are observed. Thus by adopting the whole process management model, the catalyst life can be further extended, and the catalytic potential can be fully taken advantage of.

Study on Methodology of SCR Catalyst Macroscopical Performance Evaluation and Lifetime Prediction

SONG Yubao, YANG Jie, JIN Lipeng, LU Chengzheng

2016, 49(4):  17-22.  DOI: 10.11930/j.issn.1004-9649.2016.04.017.06

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Regarding the significant impacts of flue gas flow fields and ash deposition on the SCR catalyst lifetime prediction in practice, the SCR reactor potential is proposed to represent and evaluate the macroscopical performance of multilayer series catalyst based on the analysis of the mass field and laboratory test data. Combined with the characterization of catalyst activity, a novel methodology is established to evaluate the macroscopical performance and precisely predict the catalyst lifetime by adopting the potential and activity degradation function. Through the degradation function of the catalyst of each layer, the specific plans of catalyst addition, replacement and regeneration can be determined. This method has been successfully used for the comparison and selection of the ultra-low NOx emission retrofitting plan of a 1 000-MW unit. The outcome indicates that low NOx combustion retrofit and used catalyst regeneration are both efficient and economical ways to improve the SCR performance. Nevertheless, the combination of these two methods together can achieve the best effects.

The Measures to Regulate the Influencing Factors of Low NO_x Emission and Their Effectiveness Analysis

WANG Jianfeng, RAO Wangping, LI Zhuang, WANG Fengji

2016, 49(4):  23-26.  DOI: 10.11930/j.issn.1004-9649.2016.04.023.04

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Through the test study on the SCR denitration device in coal-fired power plants, it is observed that the air leakage in the SCR equipments and the electrostatic precipitator cause the NO_x emission concentration to increase. Moreover, the differences of flue gas speed and the unevenness of NH₃ /NO_x ratio at SCR device inlet also contribute to the ammonia slip increase and thus lower down the denitration efficiency. Therefore, the regulation on these parameters is conducted, which can successfully alleviate the unevenness of the flue gas speed, reduce the ammonia slip rate and the NO_x concentration and improve the denitration efficiency. Based on the test case study, it is recommended that for the SCR equipments in coal-fired power plants, flow field design should be optimized before commissioning and regulation test should also be conducted periodically after commissioning.

Power System

Technology Research on Improving Anti-temperature Interference for Watt-hour-meter Field Calibrator

LI Zuofeng, HUANG Qifeng, ZHENG Aixia, YANG Shihai, ZHOU Gan, CHEN Mingming, ZHAO Shuangshuang

2016, 49(4):  27-31.  DOI: 10.11930/j.issn.1004-9649.2016.04.027.05

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Influenced by high or low environment temperature, measurement accuracy of watt-hour-meter calibrator may decrease significantly and unable to calibrate correctly. Based on measuring principle and hardware structure of watt-hour-meter field calibrator, mechanism of environment temperature influence on measurement accuracy is analyzed. A novel hardware improvement scheme is proposed based on temperature coefficients optimization of key electronical components. The experimental results on prototype equipment show that average temperature coefficient is less than 0.08/℃. The prototype meets 0.05S measuring precision in temperature ranging from -30 ℃ to 55 ℃.

The Impact of Converter Valve’s on-off on the Surface Electric Field of the Tower Arrester Grading Ring

DONG Zhiyong, DU Zhiye, RUAN Jiangjun, JIN Shuo, ZHOU Sheng, HU Rong, SUN bangxin

2016, 49(4):  32-37.  DOI: 10.11930/j.issn.1004-9649.2016.04.032.06

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In order to analyze the impact of converter valve’s on-off on the tower arrester grading ring, the electrostatitic field finite element method is applied to analyze the electric field distribution on the surface of tower arrester grading ring. Firstly, the loading mode in calculation is analyzed for each valve assembly of the converter valves based on the principle of the 12 pulse rectifier circuit. Then, the potential waveform of main equipment in the valve hall under rated power and light load power is obtained by simulation. Finally, by using the instantaneous loading method of electrostatic field, the distribution characteristics and the maximum value location of the electric field intensity on the tower arrester grading ring is obtained under various working conditions. It is found through analyzing the maximum electric field intensity on the tower arrester grading ring and the converter valve’s on-off state, that the maximum electric field intensity on the tower arrester grading ring under OFF state is higher than that under ON state, which shows that the converter valve on the OFF state had greater impact on the equipment around than that on the ON state.

Study on Aeolian Vibration Power of Transmission Line under Self-damping Condition

LI Qing, FANG Haoming, ZHANG Yan, HAN Lin, LU Zhongbin

2016, 49(4):  38-41.  DOI: 10.11930/j.issn.1004-9649.2016.04.038.04

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In order to understand the vibration state of overhead transmission line and ensure the operational security, it is necessary to determine the wind vibrating power curve for a large-span overhead conductor. In this paper, the data of wind vibrating balance point and wind vibration power point are obtained by using the Slethei wind energy curve, Diana wind energy curve, and the experimental results of the self-damping characteristics of conductor AACSR-400. The calculation result of the wind-vibration power point of conductor AACSR-400 shows that the Diana curve is better than the Slethei curve for determining the wind vibrating balance point of the conductor.

Assessment Method for Power Emergency Group Decision-making based on Cloud Model

LI Huanwen, WEI Meng, CHEN Yuqing, LIN Zhenzhi

2016, 49(4):  42-48.  DOI: 10.11930/j.issn.1004-9649.2016.04.042.07

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In recent years, modern power system is moving in the direction of high interconnectivity and complexity, which is inherently accompanied by a high degree of vulnerability and hazards of huge accident. Therefore, an efficient power emergency management is particularly important. The assessment method for power emergency is aimed to fully and effectively evaluate the emergency response capacity of power grid enterprises after a blackout and determine the objectives and direction of power emergency work. On the basis of the power emergency evaluation system established by Analytical Hierarchy Process(AHP), a new method and theory of power emergency group decision-making based on cloud model is introduced. The cloud model is firstly employed to solve the power emergency problems. The transformation between qualitative and quantitative in the evaluation process is realized with the fuzziness by considering the subjectivity of group decision-making. Finally, a numerical example is served to demonstrate the reasonableness and effectiveness of the developed method.

Space Curve of Iced Overhead Transmission Line

ZHANG Jian, HE Qing, WEI Jingyi

2016, 49(4):  49-54.  DOI: 10.11930/j.issn.1004-9649.2016.04.049.06

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Because of differences of geographical locations and weather conditions, a series of static and dynamic problems exist in the transmission line system. Determining space curve of overhead transmission line is basic prerequisite for researching dynamic problems of iced transmission line. After review of two existing calculation methods, a new unified method for calculating transmission line space curve is proposed. Taken an existing overhead transmission line as example, the space curves under different ice thicknesses and elevation angles are calculated by both former and proposed methods. Calculation results show that proposed method yields more accurate and practical results.

Design of Transmission Line Anti-bird Board by Applying the Discharge of Capacitor Voltage of Insulators

LI Kai, LIU Xihe, YU Shijun, TANG Guofeng

2016, 49(4):  55-60.  DOI: 10.11930/j.issn.1004-9649.2016.04.055.06

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Birds trouble accident is the principal risk factor affecting the safe operation of overhead transmission lines. In view of the defects of common anti-bird devices, a new anti-bird method is proposed in this paper by utilizing the discharge of capacitor voltage of insulators based on the fact that the insulators of high voltage transmission line are alive, and an anti-bird board is developed by using the proposed method. The reliability and validity of the anti-bird board is confirmed by laboratory experiment, field anti-bird experiment, suitability assessment and long-term field experiment. The anti-bird board of utilizing discharge of capacitor voltage of insulator can not only expel birds efficiently, but also make birds fear anti-bird board because of the conditioned reflex. It has high utility value for preventing birds trouble because of its simple structure, easy installation and structural durability.

Seismic Fragility Analysis of Connected Post Insulators

LI Sheng, CHENG Yongfeng, LU Zhicheng, ZHU Zhubing, QIU Ning, CHEN Guoqiang

2016, 49(4):  61-66.  DOI: 10.11930/j.issn.1004-9649.2016.04.061.06

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In order to assess the seismic reliability of connected post insulators system,the randomness of input waveform and input direction of ground motions need to be considered. On the basis of discussing the finite element modeling and analysis method, the damage probabilities of a typical connected post insulators system under different ground motion intensities and input directions are obtained by using the probabilistic seismic fragility analysis theory. The results show that the failure probability of the connected post insulators system is 16.2% under 8-degree intensity earthquake with transverse motion input. By taking the failure probability as assessment indicator, the fragility analysis method unifies the seismic performance indicator of electrical equipment and lays a foundation for seismic reliability analysis of a whole substation.

Development of 10 kV Thyristor Controlled Capacitor (TCC) Dynamic Var Compensator

WANG Minhui, LI Minzu, WANG Wu, WANG Shirong, WEI Xuejun, YANG Yan, TANG Jiashi

2016, 49(4):  67-72.  DOI: 10.11930/j.issn.1004-9649.2016.04.067.06

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A Thyristor Controlled Capacitor (TCC) Dynamic Var Compensator is developed and put into trial operation. The primary electric wiring device is designed, and related control and protection device is also developed. The steady state characteristics and transient behaviors of corresponding voltage and current of device are tested. Automatic voltage regulation, automatic power factor change and reactive power regulation experiments are completed under 10 kV voltage. The device response time is also tested. Test results show that reactive power regulation of device meets design requirements. There are small impact current(rush current, surge current) and no high order harmonic waves at device switching. The changing stage time is less than 10 ms. The system response time of this device is 30~40 ms. It can realize voltage regulation, power factor and reactive power regulation quickly and frequently. It can be put into practical application. Further optimization can reduce device cost per MV·A close to MSC level.

A Stochastic Programming Based Algorithm for Computing Optimal Positive and Negative Spinning Reserve

CHEN Gang,LIU Jiankun, ZHOU Qian, ZHANG Ningyu

2016, 49(4):  73-78.  DOI: 10.11930/j.issn.1004-9649.2016.04.073.06

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This paper introduces a stochastic programming based model with two-stage recourse to study the impact of positive and negative spinning reserve on the operating cost of a power system. The objective function of the proposed model is the total system operating cost which consists of two parts: one is planned operating cost calculated based on forecast load and wind power output under certainty; the other is recourse cost associated with running positive or negative spinning reserve as well as purchasing extra positive spinning reserve when active power is imbalanced. The recourse cost is presented in the form of expected value due to the stochastic nature of load and wind power. The impact of different positive and negative spinning reserve on the operating cost is analyzed using LR(Lagrangian Relaxation) method and Monte Carlo simulation. The results show that: the total system operating cost is rising in line with the increase of negative spinning reserve. When the randomness associated with load and wind power is high, an optimal reserve capacity exits between max and min positive reserve to minimize the total operating cost. Finally, the PSO(Particle Swarm Optimization) algorithm is applied to a system of 10 units to solve the optimal positive and negative spinning reserve.

A Discussion on the Design of Amorphous Transformer for Wind Farm

CHEN Haihua

2016, 49(4):  79-82.  DOI: 10.11930/j.issn.1004-9649.2016.04.079.04

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An excellent magnetic property of amorphous alloy is low losses. The wider use of amorphous alloy for wind farm projects could result in meaningful economic value and significant benefits in energy conservation and emission reductions, therefore meets the dual requirements of the project construction and the environment protection. Based on an assessment of about 20 wind projects located in Changle Qipanshan wind farms in Fujian Province, the study analyzes 6 different kinds of transformers based on a 50 MW wind farm. The transformers that maintained workable conditions are then replaced with amorphous alloy transformers. The life cycle cost analysis indicates amorphous alloy transformers have obvious techno-economic advantages as well as outstanding environmental benefits.

AC-corrected Model and Method for Intra-day Generation Scheduling

WANG Tieqiang, SUN Guanghui, CAO Xin, YANG Xiaodong, KUANG Honghui, GUO Shaoqing

2016, 49(4):  83-87.  DOI: 10.11930/j.issn.1004-9649.2016.04.083.05

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In order to improve computational efficiency and power flow accuracy, an AC-corrected model and method for intra-day generation scheduling is proposed. The intra-day generation scheduling optimization model based on DC flow is established first, then the optimization generation plan is created with consideration of network security constraints under normal and N-1 contingency scenarios. An AC-corrected model is built with objective of minimizing overall generation power output adjustment based on obtained generation active power schedule and reactive load forecast or historical distribution. This model corrects generation power outputs and therefore improves accuracy of network power flow to meet real-time operation requirements. The case study of a real power system show that proposed model and method can effectively improve computational efficiency and power flow accuracy as expected.

Study on Maximum Penetration Level of Distributed Generation in Distribution Network by Considering Current Protection

MA Xiaobo

2016, 49(4):  88-92.  DOI: 10.11930/j.issn.1004-9649.2016.04.088.05

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Integration of distributed generation(DG) to the distribution network has significantly altered the traditional power supply fashion of single power source, which could possibly lead to the malfunction of the existing current protections. To solve the problem, an optimization model is established in this paper for calculating the penetration level of DG, in which the allowable maximum penetration level of DG is taken as objective function and the correct operation of current protection as constraints. Under the condition of multi-DGs, the mathematical model is realized based on niche genetic algorithm. Through the case study on actual distribution system, the correctness and effectiveness of the proposed method are verified.

Comparative Analysis of UHV Transformer Regulation Compensation Method

ZHAO Hongfei, CHEN Xiaogui, ZHANG Guojing, MA Hongzhong, WANG Pengfei

2016, 49(4):  93-96.  DOI: 10.11930/j.issn.1004-9649.2016.04.093.04

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Currently UHV transformers use neutral point magnetic flux mode to adjust the voltage. Although the use of neutral point adjustment leads to low-side voltage change, it can satisfy voltage adjustment requirements by careful selection of compensation windings and voltage negative feedback loop. Two common UHV transformer voltage regulator and compensation methods are introduced in order to compare their operation characteristics. The winding electromagnetic relationship of two compensation methods is given and compared in detail. The results show that fully compensation method has smaller low-side voltage fluctuations and yields better regulation performance than incomplete compensation method.

Analysis and Experimental Study on the Effect of Load to CT Energy Extracting Device

YU Yuming, CHEN Changtao, ZOU Zhenyu, CHEN Bo, LI Kejun, LOU Jie

2016, 49(4):  97-102.  DOI: 10.11930/j.issn.1004-9649.2016.04.097.06

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CT can be used as the power supply of on-line monitoring device on high voltage line. It has advantages of high power, simple structure, stable and reliable operation. Experiments are performed on coil with nano-crystalline and silicon core. Results show that coil with nano-crystalline core can get more power when connecting with resistor load. The output characteristics of coil connected with bridge rectifier and filter capacitor circuit are also discussed. A power control circuit is designed to limit output power with large current amount. The proposed design has ability to prevent rear circuit overvoltage and suppress iron core saturation. The experiment results prove the effectiveness of proposed design.

Generation Technology

Modified Methodology of Heating Unit Modeling Considering Miscellaneous Generation Losses

WANG Yi, ZHANG Wei, WANG Songyan, SHI Xuemei

2016, 49(4):  103-107.  DOI: 10.11930/j.issn.1004-9649.2016.04.103.05

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The heating unit modeling using energy balance makes it possible to calculate real time maximum and minimum power outputs according to the information of residential and industrial heat supplies, which will provide valid information such as the power output range of cogeneration units for system dispatcher. However, the heat losses such as steam leakage of valves caused by steam turbine internal flow is not taken into account in the modeling with theoretical energy balance methodology, which incurs significant errors in practical operation of heating generators. Based on the facts that high correlation exists between the actual power curve and the theoretical curve under different heat supplies, the linear combinatory expressions identical to theoretical model structure is added to the rectified model. Meanwhile all parameters are re-identified by utilizing the least squares methodology. After correction, the heat losses are fully considered in the rectified energy balance model, which can reflect the relationship between power output and heat supply of heating units more precisely. The accuracy, reasonableness and feasibility of the rectified model are verified through field tests.

Research on Cooling Surface Expansion of a 1 000-MW Turbine Condenser

CHENG Dongtao, ZHANG Huan

2016, 49(4):  108-111.  DOI: 10.11930/j.issn.1004-9649.2016.04.108.04

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Being as an important indicator for condenser type selection, the cooling surface area has significant effects on condenser operating vacuum. Taking a 1 000-MW steam turbine unit for example, the effects of condenser cooling surface expansion on the cold end performance are analyzed and calculated, reasonable suggestions on new units preparation for the power plant are provided, and the comprehensive analytical methodology is formed for this issue. For large steam turbine units, the diagnostic analysis should be conducted to determine the major causes and solutions when problems existing in the cold end system are figured out.

Analysis and Research on Steam Turbine Flow Remoulding for Energy Conservation and Countermeasures

LIU Xiaohong, PEI Dongsheng, WANG Libo, CUI Laijian

2016, 49(4):  112-118.  DOI: 10.11930/j.issn.1004-9649.2016.04.112.07

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Flow remoulding is the important method for economical efficiency improvement on commissioned steam turbines. It can not only increase the efficiency and load, but also cut down the construction investment. However, there are also problems brought about by the remoulding which should not be ignored, such as steam turbine flow capacity enlargement, economical efficiency reduction in part loads, initial steam pressure, temperature and feedwater temperature deviation from the designed values, sealing steam leakage enlargement at the joint of HP and MP cylinders, and unconspicuous HP cylinder efficiency improvement. In this paper, the analysis and study on these problems in steam turbine flow remoulding are conducted and the corresponding solutions are put forward.

Flow Characteristics Analysis and Optimization of the Main Steam Control Valve in 300-MW Steam Turbine Units

ZHENG Guo, ZHANG Ganquan, HU Yanming

2016, 49(4):  119-123.  DOI: 10.11930/j.issn.1004-9649.2016.04.119.05

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In order to reduce the high pressure losses and the highfault rate of the main steam control valve for the 300-MW class steam-generator units, the numerical simulation is applied to analyze the flow characteristics and optimize the cavity profile of the valve for aerodynamic performance improvement. Combining the simulation results with the field conditions, the general modification is conducted on the valve, in which the structure optimization and the advanced valve management technology are adopted to lower the pressure losses. The modification has made the performance of the valve remarkably improved with better safety and economy.

Optimization of Tangential Boiler Furnace Temperature Field Balance

MA Ping, LIU Nannan, WANG Zhen, ZHAO Qian

2016, 49(4):  124-130.  DOI: 10.11930/j.issn.1004-9649.2016.04.124.07

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The balance of the power plant boiler furnace temperature field is closely related to the safe and stable operation of the boiler, especially in tangentially-fired boilers, the flame center often tends to deflect. To solve this problem, the main factors affecting the temperature field balance are analyzed from the aspect of the formation of the flame center. The relationship between the secondary throttle opening and the furnace temperature is figured out. The regression forecast model for the temperature field balance under stable conditions is established in LSSVM to determine the optimization plan based on the experimental results. By using the genetic algorithm (GA), the variation of the secondary throttle opening is optimized to reduce the flame center deflection. The results demonstrate that the accuracy of the LSSVM model is high with strong generalization ability, and the temperature field balance is improved after the optimization with the genetic algorithm.

Economic Benefits Analysis of Heat and Electricity Load Distribution

PANG Le, WANG Baoyu, HUANG Libin

2016, 49(4):  131-133.  DOI: 10.11930/j.issn.1004-9649.2016.04.131.03

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In order to evaluate the efficiency of cogeneration power plants as the main body of the market economy, taking the fuel input and product output of cogeneration units as the study objectives, the concept of economic benefits coefficient is proposed by considering the economic value of the heating and generating capacities of cogeneration units. The calculation model of the concept is also established. From the perspective of macro economy, the method based on the economic value generated by unit fuel consumption is proposed to assess the energy efficiency of cogeneration power plants. It overcomes the disadvantage of the traditional method that uses the quantity and quality of energy to analyze the cogeneration unit cost allocation, and has some market economics significance. In addition, a sample calculation is given based on a 300-MW extraction condensing turbine. The results indicate that the calculation method is simple and practical, and can provide effective solution to reasonable heat and power pricing and scheduling.

Simulation and Optimization of a Triple-Column Cycle for Oxygen Production of 200-MW Oxyfuel Power Plant

HAN Tao, YU Xuehai, LIAO Haiyan, WANG Yanjun, HUANG Ke, LIAO Bin

2016, 49(4):  134-140.  DOI: 10.11930/j.issn.1004-9649.2016.04.134.07

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To reduce the energy consumption of oxygen production by air separation and improve the efficiency of oxyfuel power generation, a new triple-column cycle for oxygen production is proposed based on the oxygen requirements of the oxyfuel combustion. With the help of Hysys software, the cycle is simulated, in which the key parameters, such as the plate number, the feed position and the suction pressure of the air compressor are optimized, and the energy consumption for oxygen production with different oxygen concentrations is also analyzed. It is found that the energy consumption for oxygen production increases with the growth of oxygen concentration. When the oxygen concentration is below 99%, the energy consumption of the proposed cycle is always lower than that of the traditional double- column cycle. Typically, with the oxygen concentration being 97%, the energy consumption of the proposed triple-column cycle is about 0.3544 kWh/m3, 10% lower than that of the double-column one. Therefore, it is concluded that the energy consumption of the triple-column cycle is lower than that of the double-column cycle, and it can be a reference for further reduction of the energy consumption for oxygen production in the oxyfuel power plants.

Multi-Objective Sensitivity Analysis of Gas-Fired Distributed Energy Resource

WU Kaibin, XU Chaoyang, QIU Zejing, PENG Xudong, WANG Zhenyu

2016, 49(4):  141-145.  DOI: 10.11930/j.issn.1004-9649.2016.04.141.05

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In order to acquire the parameters with higher impacts on the energy efficiency, economical efficiency and environment economy of the gas-fired distributed energy for the purpose of supervising the construction and operation of the projects, in this paper the efficiency calculation and sensitivity analysis model is established in terms of the thermal performance, engineering economy and environmental performance of the gas-fired distributed energy resource system. In addition, a case study of the gas-fired distributed energy project for an international airport is conducted. The results show that the improvement in power generation efficiency and cooling system COP are helpful for the substantial increase in primary-energy-saving rate. The prices of natural gas and cold have greater impacts on system economy and should be given full consideration in the design and application of gas-fire distributed energy projects. NOx and SO2 have significant impacts on the emission reduction income while CO2 has greater impact on the environment.

Cause Analysis and Treatment on Acid Value Exceeding Standard after Fire-Resistant Oil Change

NI Ronghua, SUN Xiaodong, LIU Xiaoying

2016, 49(4):  146-148.  DOI: 10.11930/j.issn.1004-9649.2016.04.146.03

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In a power plant of Gansu province, the acid value exceeded the relevant standard again shortly after twice of fire-resistant oil change for the governor system. In order to solve this problem, this paper studies the effects of temperatures and deteriorated products on the acid value of fire-resistant oil, and conducts test study on the regeneration effects of deteriorated oil treated by different media. The results show that the deteriorated products remaining in the oil system accelerates the deterioration, which is the major reason for the acid value exceeding the standard shortly after the oil change. The selective strong polar silicon aluminum adsorbent is capable of removing the deteriorated products from the oil system thoroughly such that the acid value of the processed oil is even better than that of fresh oil, which exhibits excellent aging-resistant performance. Therefore, the power plant replaced the filter element with the selective strong polar silicon aluminum absorbent for the online oil purification device. In this way the problem has been completely resolved.

The Effect of Computed Radiographic Resolution on Image Quality

WANG Bin, HUA Xiongfei, ZHONG Hua, FANG Songli, LU Xizhi

2016, 49(4):  149-153.  DOI: 10.11930/j.issn.1004-9649.2016.04.149.05

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The resolution of computed radiography (CR) technology is an important parameter to describe the digital image quality, which is characterized by its particularity compared with the traditional film technology. In order to introduce the CR technology to the nondestructive testing of nuclear power plants, the factors affecting the resolution are analyzed and tested. The test results show that the contrast resolution and the spatial resolution are quite critical to the CR image quality. The outcome from the study can provide solid references to determine technical parameters of CR technology.

A Comprehensive Weighting and TOPSIS Method Based Assessment on the Impact of Grid-Connected PV Generation

CHEN Li, HU Po, YANG Deshuai, LIU Dian, WANG Jing, JIANG Xiaoliang

2016, 49(4):  154-159.  DOI: 10.11930/j.issn.1004-9649.2016.04.154.06

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The current evaluation index for assessing the impact of grid-connected PV generation is neither adequate nor sufficiently meaningful. This paper proposes a more comprehensive two-stage evaluation index system. The weights of primary and secondary indexes are estimated based on the subjective weight method and the entropy method respectively. The comprehensive weight for the secondary index is then obtained. The comprehensive assessment of the impact of grid-connected PV generation based on comprehensive weights and TOPSIS(technique for order preference by similarity to ideal solution, TOPSIS) method can not only reflect the superiority of subjective weighting, but also make full use of data information to make the evaluation results more realistic. The case examples show that such approach is a reasonable and effective evaluation method.

Photovoltaic Generator Grid-Friendly Connection System and Simulation Study

SU Yuankai, , ZHANG Jie, HU Shihao, SU Yimin, SU Shiping, LIU Guiying

2016, 49(4):  160-165.  DOI: 10.11930/j.issn.1004-9649.2016.04.160.06

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A new type of inverter for grid-friendly connection of photovoltaic generator is studied and simulated to improve power quality of the main grid. The inverter system makes use of a two-level DC/DC and DC/AC structure and utilizes three-phase instantaneous reactive power theory to detect reactive power and harmonic currents. The inverter is combined with Active Power Filter(APF) to not only produce active power but also compensate reactive power and harmonics, enabling grid-friendly interconnection. The DC/DC circuit of the inverter system uses boost circuit and performs maximum power tracking based on the conductance increment method. The DC/AC circuit of the system uses three-phase bridge voltage inverter circuit and hysteresis control method. Finally, the simulation model and simulation results are provided to verify the feasibility of the proposed grid-friendly connection inverter for photovoltaic.

Voltage and Frequency Control Optimization for Distributed Generation Based Grid

LI Mingde, XIA Xiangyang, WANG Jinlong, LUO Jiping, HUANG Hai, CHEN Guoli, LIU Qifan

2016, 49(4):  166-169.  DOI: 10.11930/j.issn.1004-9649.2016.04.166.04

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This paper introduces a multi-parameter hysteresis-band current control strategy based on grid connected inverters to address the intermittent and instability issues associated with photovoltaic power generation. The control strategy is based on a minimum DC side voltage of 600 V and uses ring-width feedback control together with hysteresis-band current control. A PI control is used to adjust the ring-width to maintain a relative stable on/off switching frequency, deliver high system energy conversion efficiency, improve the robustness and dynamic performance of the system, and deliver high quality power to the grid. Finally, a simulation of the inverter system under the premise of minimal DC side voltage of 600 V is presented, with results confirming the superior performance of the proposed control strategy.

Technology Economics

Clean Energy Generation Oriented Initial Quota Allocation Method for Carbon Emissions Trading of West-East Power Transmission

CHEN Li,, ZHANG Xiangyu, JU Liwei, YU Shunkun, TAN Zhongfu

2016, 49(4):  170-173.  DOI: 10.11930/j.issn.1004-9649.2016.04.170.04

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West-East power transmission project of China southern power grid is based hydropower and clean hydropower replacement the high emission of thermal power, with significant environmental benefits, but the economic compensation is very limited. Carbon emissions trading is introduced into the West-East power transmission. The method of initial quota allocation of Carbon Emission Trading which oriented clean energy generation is proposed considering the actual situation of China Southern Power Grid provinces. Firstly, according to historical carbon emissions, carbon reduction coefficient is ensured and the initial carbon allowances are get. Secondly, the second round of allocation Carbon allowances could be get based on the proportion of clean energy power generation capacity. Finally, using this method, the four provinces(districts) in the south of China were measured in 2015. The results were in agreement with the actual environmental capacity, provided the trading space for carbon trading, which is conducive to the development of carbon trading, and indicate that the method is scientific and effective.

Sensitivity Analysis of Micro-grid Scheduling to on-Grid Price and DG Subsidies

ZHANG Shixiang, TIAN Qindan

2016, 49(4):  174-180.  DOI: 10.11930/j.issn.1004-9649.2016.04.174.07

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Facing severe haze problems in many parts of China, the Chinese government vigorously supports the development and utilization of new energy sources. In addition to subsidies, the distributed generations(DGs) are opened to be integrated to the grid. With consideration of each DG’s generating and carbon emissions cost in a micro-grid, and by taking one day as an optimization cycle and the economy, environmental protection, emission reduction and reliability as objective, a low-carbon scheduling model of micro-grid is established, and a low-carbon micro-grid scheduling strategy of micro-grid is developed. The chaotic particle swarm optimization algorithm is used to adjust the output of each DG and the purchase/sale quantity of electricity from the main grid, so as to realize the lowest low-carbon composite cost in a day within a micro-grid. On this basis, a sensitivity analysis is conducted on the micro-grid scheduling to the on-grid price and DG subsidies, which can provide a reference for the government to formulate the policy on promoting micro-grid construction, energy-saving and emission-reduction, and new energy development.

Forecasting Analysis and Subsidy Strategy on Renewable Energy Consumption of China

ZHAO Wenhui, GAO Jiaoqian, SONG Yajun, HUANG Haitao

2016, 49(4):  181-187.  DOI: 10.11930/j.issn.1004-9649.2016.04.181.07

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The consumption of renewable energy is influenced by several factors, and the gray model cannot make accurate forecast in this case. The renewable energy consumption in China is simulated and forecasted based on combination of buffer operator and grey GM(1, 1) model. Impact of policy subsidy on renewable energy consumption is also discussed. Two kinds of subsidy strategy models based on renewable energy consumption forecasting are established to explore the impact strength of policy subsidy on renewable energy consumption. Excel is used to solve the model and the result shows that the GM(1, 1) method combined with buffer operator has better fitting accuracy. During period of 2013-2020, the ratio of renewable energy consumption trend to increase. However, the growth rate without policy subsidies is significantly lower than that with continuation of the original policy subsidies. In addition, in order to successfully complete plan goal of “long-term planning for renewable energy development”, policy subsidy need to be adjust to at least 1.65 times of previous value.

Life Cycle Type-selection for Electric Power Transmission Line Fittings

BAI Dandan, DAI Yujian, LI Qifeng, LI Chen

2016, 49(4):  188-191.  DOI: 10.11930/j.issn.1004-9649.2016.04.188.00

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In view of the hysteresis and eddy energy loss surge caused by the extensive use of ferromagnetic materials in traditional fittings, a new life cycle design concept is proposed to optimize the manufacturing materials and structure of transmission line fittings. With consideration of the comprehensive economic costs of fittings, include the purchasing, transportation and installation cost, operating loss cost, troubleshooting cost, service life, safety reliability and environmental protection, a life cycle type-selection model is developed in this paper for power line fittings. Based on the collected data of fitting manufacturers, the proposed model is applied to a real transmission line project for comprehensive evaluation of fittings’ life cycle cost. According to the result, the fitting types that conform both the actual demand and life cycle design concept are recommended to improve the overall economic and social benefits of the transmission line projects.