Table of Content

05 January 2019, Volume 52 Issue 1

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Research on Deep Integration of Power Cyber Physical System under Energy Internet Goals

LIU Lin, ZHANG Yunzhou, WANG Xue, JIANG Yizhe, ZUO Xinqiang, DAI Hongcai

2019, 52(1):  2-9.  DOI: 10.11930/j.issn.1004-9649.201810064

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Energy internet is a smart integrated energy system that can solve current energy problems and promote the transformation of energy system, and it is of great significance in increasing the proportion of renewable energy, promoting the clean and efficient use of fossil energy, and improving the overall efficiency of energy. The integration of power system and cyber-physical system is the core foundation for building energy internet, and the integration level is an important factor for determining the development stage of energy internet. Based on a study of the value and framework of power and cyber system integration, as well as its relationship with energy internet, a quantitative analysis is made for a long historical period (1900-2018) to reveal the law of development for power and cyber system integration, and predict the development trend and bottlenecks in future, and the key strategic direction is proposed for energy construction, which can provide a theoretical basis and decision-making reference for the construction and development of energy internet in China.

Theoretical Architecture and Typical Scenario Applications of Cyber Physical Systems in the Distribution Network

ZHENG Peixiang

2019, 52(1):  10-16,31.  DOI: 10.11930/j.issn.1004-9649.201806057

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Along with the application of computer science, communication and control (abbreviated as 3C) in distribution power network, information exchange among the physical components of distribution power network is substantially enhanced. Furthermore, its capability of perception, integration, coordination and autonomy is also strengthened. This kind of technology is named cyber physical system (CPS). This paper investigates the mechanism of the CPS of distribution power network from the perspective of cyber physical integration, so as to figure out the impact of diversified control modes and CPS configuration on the operational characteristics of the distribution power network. The theory of CPS is validated by analyzing three representative applications. In the analysis, three aspects, including the historical development, various demands and application situations, are taken into consideration.

Research on Integrated Modeling Method and Interactive Influence Mechanism of Distribution Network CPS

LI Hong, ZHU Hong, YANG Zhihong, TANG Chenghong, ZHANG Ming, ZHOU Dongxu

2019, 52(1):  17-24.  DOI: 10.11930/j.issn.1004-9649.201808134

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The improvement of communication and information technology has greatly enhanced the observability and controllability of distribution network. It is necessary to further study the operation characteristics of distribution network from the perspective of cyber physical system (CPS). This paper mainly studies the CPS-based integrated modeling and interaction mechanism of distribution network system. Firstly, a unified modeling method is proposed for distribution system and distribution information system. And then the dynamic interactive influence mechanism of distribution network CPS is studied, and the integrated CPS dynamic interaction model of distribution network is constructed using the distributed generation as the intelligent control and processing terminal. Finally, the dynamic impact of communication faults in distribution network CPS on physical links is analyzed and simulated through testing cases, which has proved the validity of the model.

Reliability Analysis of the Current Differential Protection with Integration of Cyber and Physical System

LI Manli, CHEN Xuetong, LIU Dongyang, DING Weidong

2019, 52(1):  25-31.  DOI: 10.11930/j.issn.1004-9649.201807084

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Modern power system is developing into a cyber physical power system (CPPS). The current differential protection is a typical application with ICT and physical function tightly coupled. So it is necessary to study its reliability from the perspective of CPPS. On the basis of the closed-loop control process of physical-measurement-communication-decision making, the paper analyzes the integrated effects of cyber and physical factors, such as line current, measurement error of CT, communication delay and protection criteria, on the current differential protection, and proposes the mis-operation probability model of the current differential protection. On that basis, a simulation is performed to verify the model, and the key factors affecting the reliability are analyzed.

Discussion on Communication Requirement and Network Resource Allocation Scheme of Cyber Physical System for Distribution Network

LIANG Yun, HUANG Li, HOU Xingzhe, XU Xin, HU Zhiyuan, WANG Dayang

2019, 52(1):  32-39.  DOI: 10.11930/j.issn.1004-9649.201806064

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The paper analyses the properties of cyber physical system (CPS) for distribution network and the differences to telecom internet system, and points out that the CPS is characterized by that the communication network is involved in automatic process. The communication requirements are divided into two aspects including IT dataflow and OT control process, and their communication parameters and reliability mechanism are analyzed. Then, the universal carrying network model is proposed to improve the efficiency and ability of network resources management, and a multi-objective resource allocation scheme is established to meet the different requirements of IT and OT. Finally, the model and scheme is proved to be reasonable through a case study of a typical distribution network CPS.

Research on Information and Communication Support for Transnational Interconnection of Power Dispatching and Trading Systems

GAO Zhiyuan, HUANG Haifeng, SUN Qian, ZHANG Hong, CAO Yang, TANG Baoguo

2019, 52(1):  40-47.  DOI: 10.11930/j.issn.1004-9649.201805091

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The support of information and communication technologies (ICT) for transnational interconnection of power dispatching and trading systems has important theoretical and practical significance for the construction of global energy interconnection. Based on the theory of cyber physical systems and SWOT analysis method, the related issues are studied and designed around the core architecture by using various existing technologies. The general architecture is proposed for the transnational interconnection of power dispatching and trading systems, including the conceptual model, technology framework, deployment architecture and functional interfaces. The key technologies are analyzed, such as the communication supports, interactive protocols, interchange of power grid models and related data, and application of information technologies. The assurance system is designed for security and reliablity. And an exemplary interconnection design is made for transnational interconnection of power dispatching and trading systems in Northeast Asia.

A New Security Risk Assessment Method for Cyber Physical Power System Based on Attack Prediction

HAN Lifang, HU Bowen, YANG Jun, YING Huan, ZHOU Chunjie, FANG Xikang

2019, 52(1):  48-56.  DOI: 10.11930/j.issn.1004-9649.201809104

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In order to analyze the current risk status of the cyber physical system (CPS) in power system, this paper proposes a risk assessment method for cyber physical power system based on attack prediction, with consideration of the close coupling characteristics of cyber system and power system. Firstly, we use alert message to identify the possible attack scenarios based on the hidden Markov model (HMM), and speculate the attacker's attack intention and analyze the next attack target and attack probability. The results of attack prediction represent the current attack threat status of the system and are used as the input of the risk assessment process. Secondly, we use the traditional single-domain (cyber domain or physical domain) risk assessment method to calculate the single-domain risk, and then assess the cross-domain risk based on the complex network model of cyber physical power system. The final risk value is obtained through integrating the results of both domains. Based on the smart distribution network simulation platform of IEEE 33 BUS, the attack prediction method and risk assessment method are verified, and the results have proved the feasibility and rationality of the attack prediction-based risk assessment method.

Research and Design of Automatic Penetration Testing System for Electric Vehicle Charging Piles

SUN Zhou, PAN Mingyu, CHEN Zhen, YUAN Xiaoxi, CHEN Ping

2019, 52(1):  57-62,109.  DOI: 10.11930/j.issn.1004-9649.201811139

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Cyber physical system (CPS) is an intelligent system integrating computing, communication and control. As an important gateway to the energy internet, the electric vehicle charging facilities are responsible for important functions such as power supply, metering and billing, data interconnection and charging security, which is also a typical CPS system. There are many potential threats in the charging pile terminals in the field, such as system abnormality caused by user intrusion of charging pile system, which would subsequently threaten the security of the national grid. It is therefore necessary to study and design an automatic penetration testing system for charging piles. This paper makes a research and design of the charging pile automatic penetration testing system from three aspects: fingerprint scanning, vulnerability detection and vulnerability mining, which aims to detect the known vulnerabilities and discover unknown ones, and effectively carry out all-round automatic inspection of charging electric vehicles, subsequently improving the protection level of charging piles, and strengthening the protection capability of charging piles and reducing the information leakage and economic loss caused by the attacks on charging piles.

Optimization of Offshore Wind Farm Collector Systems Based on Improved Genetic Algorithm

WANG Weiyuan, QIAO Ying, DOU Fei, YANG Lin, ZHANG Yujing

2019, 52(1):  63-68.  DOI: 10.11930/j.issn.1004-9649.201806043

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The cost of offshore wind farm's collector system constitutes a significant proportion of the wind farm's total investment, it is thus very significant to make a topology optimization of the collector system for reducing the fixed investment. The topology optimal problem can be modeled as a minimum spanning tree problem with dynamic edge weight. Because the edge weight is coupled with topology optimization, it cannot be solved by traditional methods. Through improvement in initial population selection, use of linked list coding and elite genetic operators, the improved genetic algorithm is engaged in the paper, which can not only improve the algorithm's efficiency, but also better address the complicated restrains of uncrossed marine cables. The case study shows the improved GA has good capability in optimization searching and convergence.

Assessment on the Total Transfer Capability of AC/DC System for Integrated Wind-Thermal Power

MAO Feng, GUI Qianjin, WANG Lei, LUO Lirong, XU Ruixiang, LIU Shaofan, ZHAO Wenheng

2019, 52(1):  69-75.  DOI: 10.11930/j.issn.1004-9649.201708096

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AC/DC delivery of integrated wind-thermal power will be an important form of transmission in the future in China. The volatility of wind power output and the AC/DC hybrid transmission mode bring a new challenge to the calculation of the inter-regional total transfer capacity (TTC). Firstly, a system model is established for delivery of the integrated wind-thermal power into the same receiving-end area through the AC/DC transmission channel. Considering the problem of system reactive power adequacy, a TTC calculation model is established based on the improved continuous power flow algorithm, and the single sample value is quickly acquired. Then, considering the inherent volatility of wind power and various uncertain factors in the system, the non-sequential Monte Carlo simulation method is used to evaluate the inter-regional TTC, and the result is verified by case study. It is found that the AC/DC hybrid transmission mode can improve the regional TTC of the system, and the inter-regional TTC can be improved by increasing the proportion of integrated wind-thermal power within a reasonable range. However, when the proportion of wind-thermal power is too high, only the existing grid structure is upgraded and the transmission capacity of the transmission lines is improved, can the system's TTC level be further increased.

Fault Diagnosis of UHVDC Transmission Lines Based on Improved Directional Current Method

WANG Yongjin, FAN Yanfang, LI Ziqian

2019, 52(1):  76-81.  DOI: 10.11930/j.issn.1004-9649.201803089

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Identifying the faults of UHVDC transmission system reliably and accurately is the basis of protection action inside and outside the UHVDC transmission system, which is of decisive significance to safe and reliable operation of the whole HVDC transmission system. Based on the Berrellon distributed parameter model, a fault identification criterion is proposed by introducing the transient energy deviation (the ratio of transient value to normal value) on the basis of the directional current method, which can identify rectifier outlet fault, DC line fault and inverter outlet fault in UHVDC transmission accurately. This identification method has low requirement for DC line communication channel, strong ability of resisting transition resistance and low requirement for sampling frequency. By building the ±800 kV DC transmission model in PSCAD and combining with the MATLAB, the simulation results show that the method can identify the faults of HVDC system accurately and select the fault poles, which has a certain practical engineering value.

Broken Strands Detection of Transmission Line for Rural Distribution Network Based on Aerial Image

LI Bo, CHEN Cheng

2019, 52(1):  82-87,95.  DOI: 10.11930/j.issn.1004-9649.201804103

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The aerial platform could significantly increase the efficiency of electric patrol and reduce its costs in rural distribution network, due to its wide area. However, the angle and distance of shooting are not controllable, and the illumination of environment is also capricious, which impose great challenges on the application of aerial electric patrol. In this paper, a contour information based universal broken strands detection method is proposed. Specifically, the segments of cable in the image are detected by LSD (line segment detector), and the length of the line segment is used to filter the non-wire line segments, controlling the total detection time. Meanwhile, the detection accuracy has been significantly improved by adopting the ABM (active basis model) algorithm. Simulation results validate the effectiveness and the practicality of the proposed methods.

Distribution of Electric Field and Optimization of Anti-pollution Flash Coating Parameters for Factory-Composited Insulators

WU Wenhua, ZHANG Rui, YUAN Jincan, WU Guangya, ZHANG Qin, YANG Binzhong, SHEN Yamei

2019, 52(1):  88-95.  DOI: 10.11930/j.issn.1004-9649.201805203

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In this paper, the distribution of electric field of factory- composited DC insulators under different coating thicknesses and coating processes was simulated on the basis of finite element method for the constant electric field simulation. The distributions of electric field of the insulators including without RTV coating coated insulator, fully RTV coating coated insulator, partially RTV coating coated insulator and different RTV coating thickness insulator were obtained through simulation analysis. The calculated results show that the maximum electric field strength around the pin (coating edge) will not exceed the corona onset field strength in the air both for factory-composited porcelain and glass insulators when the RTV coating thickness is not less than 0.3 mm and the coat completely covers the surface of the insulator. While the electric field strength at the edge of the steel foot is very high when coating blank exists near the pin. The results in this paper provide guidance for optimizing the parameters of the anti-fouling flash coating of factory-composited insulators.

Transient Stability Emergency Control Strategy Considering FACTS

LV Yazhou, HUO Chao, WU Xingyang, TAN Zhen, HOU Yuqiang, CUI Xiaodan, KE Xianbo, NIU Shuanbao, LI Wei

2019, 52(1):  96-101.  DOI: 10.11930/j.issn.1004-9649.201706052

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The lack of coordination between FACTS control and conventional control may threaten the security and stability of power grid. Without taking FACTS into consideration, the off-line control strategy is too conservative and the emergency control measures are heavy. Meanwhile, if the capacity of FACTS equipment is fully used in the transient process, the section limit will be so optimistic that the emergency control measures may be insufficient. A transient stability emergency control strategy is proposed with consideration of FACTS, which divides the FACTS participated transient stability control into three stages, including FACTS equipment active control, emergency execution correction strategy and in-turn additional control. With the combination of the conventional transient stability control and FACTS control, the system safety is ensured and the economic efficiency of the control measures is improved. The proposed strategy is verified by simulation of a practical power grid. The simulation results show that the participation of the FACTS in the power grid transient stability control can decrease the acceleration energy of the transient process and reduce the cutting-off number of generators while maintaining the stability of the power grid.

Method of Distribution Network Three-Phase Power Flow Calculation Based on a Hybrid Single-Three Phase Model

YANG Lei, LUO Pingping, WANG Gaomeng, LIU Yangsheng

2019, 52(1):  102-109.  DOI: 10.11930/j.issn.1004-9649.201801054

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In order to meet the requirements for computational accuracy and efficiency of three-phase power flow of distribution network, this paper proposes a model and algorithm for single-three phase hybrid power flow calculation of distribution network. Firstly, the calculation model of three-phase power flow is deduced. Then, considering the uncertainties of distribution network, the three-phase model is used for the part where significant unbalance exists, while the single-phase model is used for the part where unbalance is negligible. These two parts of network are interconnected through a single-three phase interface, realizing the unified modelling for the single-phase network and the three-phase network. Finally, the location of the interface between the single and three-phase parts is automatically determined based on the unbalanced degree of line current. The case study result has verified the feasibility and efficiency of the proposed single-three phase hybrid power flow calculation method and the dynamic selection strategy of interfaces.

Study on the Effects of Emission Reduction in Coal-Fired Power Industry on China's Air Pollutant Emission Control

LI Bo, WANG Weiliang, YAO Xuan, LYU Junfu, LI Zheng, NI Weidou

2019, 52(1):  110-117.  DOI: 10.11930/j.issn.1004-9649.201810085

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This paper briefly reviews the progress of the emission control over SO₂, NO_x and dust in China's coal-fired power industry and systematically analyzes the development of the installed capacity of emission control devices and situation of pollutant emissions in the coal-fired power industry, as well as the general situation of air pollutant emissions categorized by different industries nationwide. It is concluded that the coal-fired power industry has made remarkable contributions to China's air pollutant control in recent years. At present some energy-intensive industries, such as heat supply, iron and steel manufacturing, and cement etc. have overtaken the coal-fired power industry as the major air pollutant emission sources. Therefore, it is suggested to establish a coordinated emission control standard for these energy-intensive industries so as to strengthen the pollutant control management and focus on resolving the critical issues in environment pollutions.

Current Operation State Analysis on WGGH Equipment and Optimization Method Exploration

XU Ketao, MA Junfei, ZHANG Yang

2019, 52(1):  118-123.  DOI: 10.11930/j.issn.1004-9649.201806018

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The gas-water-gas heat exchanging system (WGGH) operation situation is analyzed through field tests and study from the aspects of gas temperature drop, system resistance, dust removing efficiency and SO₃ removing efficiency. The results show that the chimney smoke temperature can be raised through WGGH and the white smoke plume can be eliminated. Meanwhile, the removal of dust and SO₃ has obvious effect. The main problems of WGGH in operation are analyzed and the corresponding optimization and improving measures are proposed to provide important data support and theoretical basis for normal WGGH operation.

Type Selection on 1 350 MW Electrostatic Precipitator and Its Steel Frame Control on Thermal Expansion

ZHAO Haibao, HE Yuzhong, SHEN Zhi'ang, JIANG Hua, YAO Yuping

2019, 52(1):  124-128,136.  DOI: 10.11930/j.issn.1004-9649.201807105

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The recent technology development of coal-fired generation unit drives the progress of corresponding auxiliary equipments and their design techniques. Take the example of the electrostatic precipitator (ESP) installed in a 1 350 MW double reheat ultra supercritical coal-fired unit in Anhui province with cross compound steam turbine arrangement featured by separated shafts with elevated and conventional layout. The schemes for ESP type selection are analyzed and different combinations are compared, i.e., two sets with four-chamber and five-field, three sets with three-chamber and five-field, four sets with two-chamber and five-field of ESPs. Especially regarding the four-chamber ESP with better economic performance, the problem of insufficient strength caused by thermal expansion is analyzed by a finite element analysis software package and then the pre-eccentricity of pivots is developed. The result shows that the thermal expansion has significant impacts on the strength of the steel frame of large size ESPs and the pre-eccentricity of pivots can effectively reduce the internal force and deformation.

Numerical Simulation of Evaporative Evaporation of Desulfurization Wastewater by the By-pass Tower

SHE Xiaoli, PAN Weiguo, WANG Chengyao, NI Yingchun, QIN Ling

2019, 52(1):  129-136.  DOI: 10.11930/j.issn.1004-9649.201805195

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Desulfurization wastewater is difficult to be reused due to its complex composition. Therefore the flue atomization evaporation technology has been applied in the wastewater treatment at some power plants. However, the direct injection of desulfurization wastewater into the flue will cause problems such as corrosion, ash accumulation and clogging. A better option is offered by setting the bypass evaporation tower to dry the desulfurization wastewater. In order to study this technology, taking a 330 MW unit as an example, the flue gas extraction amount was determined by calculating the thermal mass balance between the desulfurization wastewater and the flue gas. Then the physical model was established, and the smoke flow field was optimized by numerical simulation. The steady state simulation was carried out for the nozzle arrangement, droplet diameter and flue gas temperature. The results show that even though the amount of flue gas extracted only accounts for 2.27% of the total flue gas volume, the flue gas flow field is enough to fill the entire evaporation tower. As a result of the atomization evaporation effect from the three nozzles, the evaporating tower outlet temperature can reach reach the designed value of 120 ℃. If the droplet diameter under 80 μm, the droplet particles will not stick to the wall. In particular the desirable evaporation effect is achieved when the droplet diameter is 60 μm. In summary, to prolong the residence time of the particles and make the particles non-adherent and less agglomerated, the flue gas swirling method is preferable with the selection of three nozzles, the atomized particle size of 60 μm and the inlet flue gas temperature of 600 K.

Phosphorus Removal by Reusing Sludge from Flue Gas Desulfurization Wastewater Treatment System

ZHU Yihao, ZHAO Xiaodan, TIAN Xiaoce, WU Junhui, DOU Weixiao, ZHOU Zhen

2019, 52(1):  137-143.  DOI: 10.11930/j.issn.1004-9649.201804023

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This paper proposes a scheme for the utilization of sludge from the FGD wastewater treatment system (desulfurization sludge) according to the characteristics of flue gas desulphurization (FGD) wastewater and the "triple box" process, The phosphorus removal technology on desulphurization sludge is studied using the simulated wastewater as the processing object. Effects of the sludge dosage and its calcium content on phosphorus removal efficiency are discussed, and the mechanism is explored with the study on adsorption thermodynamics and kinetics. The results show that phosphorus removal using calcium-containing sludge is mainly realized through chemical reaction and adsorption, and the product is CaHPO₄·2H₂O. The phosphorus removal rate is over 99% under a certain sludge concentration and calcium content. The higher the calcium content in the sludge, the greater the adsorption capacity for phosphorus and the less the sludge demand will be. In addition, the appropriate raising temperature can promote the adsorption of phosphorus to the sludge. The characterization analysis of X ray diffraction (XRD) and the scanning electron microscope (SEM) show that calcium phosphate rocks generate on the surface of the sludge, which further verifies the experimental results.

Study on the Ammonium Bisulfate Deactivated SCR Catalyst at Low Load Operation

SONG Yubao, LIU Xinhui, HE Chuan, WANG Xingjun, WANG Lele, CHENG Shijun, MA Yunlong, LIANG Junjie

2019, 52(1):  144-150.  DOI: 10.11930/j.issn.1004-9649.201711282

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Aimed at the problem of ammonium bisulfate (ABS) deactivated SCR catalyst at low load operation, the characteristics of ABS deactivation and activity recovery are studied in the simulated flue gas environment in laboratory. It indicates that the ABS liquidation-vaporization under capillary condensation is a typical invertible process and the process is positively affected by the concentration of NH₃ and SO₃ in flue gas. In addition, the empirical formula used to evaluate the MOT under the actual operating condition is proposed. Based on the case analysis of the SCR operating at low load, the principle and method to use the experience formula MOT is given to guide the selection of the best plan for SCR operating at low load and the activity recovery of the ABS deactivated catalyst.

Analysis on the Influence of the Wastewater Evaporation in Flue Duct to the Flue Gas Dew Point

WU Zhiquan, CAO Fan, YUAN Yuan, JIA Xibu

2019, 52(1):  151-155,184.  DOI: 10.11930/j.issn.1004-9649.201803207

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The effect of the wastewater evaporation in flue duct to the flue gas dew point was studied in this article. Pilot test of the wastewater evaporation was conducted on a 600 MW unit. The H₂O and SO₃ contents in the flue gas were detected and the dew point was calculated using different formulas. The results showed that, when 900~1 400 L/h wastewater was injected in 1/4 flue duct of the 600 MW unit (the amount of flue gas was 4×10⁵~5×10⁵ m³/h), the water vapor in the flue gas increased 0.7%~0.9%, whereas the SO₃ decreased by 30%~50%, which indicated that the transformation from SO₃ to sulfuric acid mist and their adsorption on fly ash particles were improved after the wastewater evaporation. The flue gas dew point decreased by 9~14 ℃ after the evaporation, and the flue gas temperature could be higher than the dew point. Thus, wastewater evaporation in flue duct could not lead to low-temperature corrosion of the downstream ducts and equipments under the condition of pilot test.

Current Situation and Improvement Measures of NO_x Monitoring System for Gas Turbine Unit

ZHANG Chengwu, XUAN Tianxing, LIU Zhitan, YANG Aiyong, SHU Xi

2019, 52(1):  156-160.  DOI: 10.11930/j.issn.1004-9649.201805181

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With the increasingly strict requirements for the concentration of NO_x emission from gas-fired units, the operating condition of the monitoring system has changed such that the original monitoring instruments becomes no longer applicable. By analyzing the NO_x monitoring technology and the flue gas pretreatment technology as well as their adaptabilities, a clear understanding of the current situation of the NO_x monitoring system for gas units is obtained. In compliance with HJ 75-2017 and HJ 76-2017 standard, regarding the issues in existing monitoring system such as large measurement range, poor measurement accuracy for low concentration and lack of NO₂ monitoring functionality a series of improvement measures are put forward, e.g., giving priority to chemiluminescence method in NO_x measuring technology, adding NO₂ monitoring devices, using low range and high precision CEMS instrument and pretreatment device with superior performance, implementation of the lightning protection facilities, etc.. Meanwhile the installation of ammonia escape, oxygen and moisture analysis instrument is taken into account in order to meet the control and monitoring requirements. The results are also applicable to regular thermal power units.

Water-Wall Temperature Control of a 1 000 MW Dual Circle Tangential Firing Boiler during Wet-Dry Transferring Period

WANG Ya'ou, TAO Qian, XIAO Jie, CHEN Bo

2019, 52(1):  161-165,173.  DOI: 10.11930/j.issn.1004-9649.201808048

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Aiming at the problems of water-wall overheating and large temperature deviations of the ultra-supercritical dual tangential circle boiler in the wet-dry transferring period, a three-stage control measure is adopted. Prior to the wet-dry transferring, the upper mills are put into operation to increase the boiler pressure and the feeding water temperature. During the transferring, an appropriate water/coal ratio and a superheating degree are settled and maintained. During the routine operation, the flame height should be kept as high as possible to improve the heat uniformity and the primary and secondary air distributions are adjusted to lower the "hot corner" temperature. In addition, the orifice plates of the overheated water-wall tubes are removed to increase the mass velocity. The results show that this measure has effectively alleviated the overheating of the water-wall and improved the water-wall operation conditions.

Study on Testing Method and Application of Water Wall Tube Temperature for Ultra-Supercritical Boiler

WANG Yang, WANG Huajian, ZHOU Hongguang, YAN Xianglin, BAI Peng, LU Qi

2019, 52(1):  166-173.  DOI: 10.11930/j.issn.1004-9649.201807038

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The measurement and control of water wall tube temperature has been a tough issue in thermal power plants. By virtue of some testing devices which are installed at special locations in the water wall tubes, the temperatures of fireside tube, backside tube and working medium inside the tube are measured and monitored on-line under various operating conditions for the analysis of the impacts of the relevant factors on the water wall temperature in daily operations. The study results show that the ramping up process after startup, the soot blowing during the load variation period and the water-coal ratio imbalance can cause or even aggravate the sharp rise of water wall tube temperature, while the ramping down process or the procedure change of coal mills do not affect much on the water wall tube temperature. The testing device and the study results can provide some guidance for the safe operation of the water wall in thermal power plants.

The Application and Prospect of Closed-Loop Optimization Control System in Thermal Power Plants

ZHANG Qiusheng, LIU Lei, WU Zhigang

2019, 52(1):  174-178.  DOI: 10.11930/j.issn.1004-9649.201809036

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The closed-loop optimization control system is capable of enhancing the automatic control quality in thermal power plants. This paper presents the requirements for the closed-loop optimization control system from domestic thermal power plants and then analyzes the architecture and effects of the imported closed-loop optimization control system in details. Based on that, it elaborates the new architecture and actual effectiveness of the domestically-manufactured system. Finally, the issues that need more attention in practice are put forward so as to provide beneficial technical reference for the power generation industry, such as self-checking, tracking and alarming functionalities in the process of switchover to DCS control.

Discussion on the Optimal Scheme of the Secondary Circuit Steam and Water Quality of the High Temperature Gas Cooled Reactor

ZHANG Ruixiang, GAO Yufeng, LI Kang, YAO Yao, WANG Zhen, XU Haosong

2019, 52(1):  179-184.  DOI: 10.11930/j.issn.1004-9649.201711228

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Referring to the thermal power plant DC unit and the pressurized water reactor standards as well as the operation experiences and in view of the secondary circuit structure and material features of the high temperature gas-cooled reactor, this paper studies three methods of controlling the secondary circuit water quality of the high temperature gas-cooled reactor, which include dosing control, the operation method of the condensate water polishing system and system flushing before unit start-up. In the end, the three methods are discussed in detail, and a scientific and complete method for optimizing the quality of water and steam in the secondary circuit of the high temperature gas-cooled reactor is formed. The method is discussed and approved by the experts, and is compiled into the commissioning outline and the operation rules for the high temperature reactor.