01 September 2019, Volume 40 Issue 9

    

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  Assessment and Optimization for Power System Flexibility with High Proportion of Wind Power

  LIU Yingqi, XIE Min, WEI Wei, ZHANG Yue, LIU Mingbo

  Electric Power Construction. 2019, 40(9): 1-10. https://doi.org/10.3969/j.issn.1000-7229.2019.09.001

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  For the flexibility assessment of power systems with high proportion of wind power, a comprehensive assessment system of flexibility combining dynamic and static indicators is proposed in this paper. Among them, the static flexibility indicator based on the technical characteristics of generation resources is used to evaluate the inherent flexibility supply capacity of various generation resources in the system. The dynamic flexibility indicator based on the operation characteristics of the power system focuses on the uncertainty and variability of wind power and load, and quantitatively assesses the lack of flexibility of the power system under different operating conditions. On this basis, a unit optimization model for minimizing flexible capacity shortage is proposed. Taking into account the optimal operation cost of the system, a dynamic optimization model for the flexible capacity shortage of power system to cope with high proportion of wind power access is constructed, which can provide reference for the transformation and planning of system flexibility. With the case study of a certain power grid, the effectiveness and rationality of the proposed composite assessment system and method of the flexibility assessment are verified.
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  Optimization of VDCOL Based on Transient Energy Function Analysis to Improve Stability of Weak Delivery System

  LU Jiali,XIE Huan,WANG Xinhao, WU Tao, ZHOU Ranran,LI Ran,LIU Yingpei

  Electric Power Construction. 2019, 40(9): 11-19. https://doi.org/10.3969/j.issn.1000-7229.2019.09.002

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  On the background of the Ximeng-Taizhou UHV weak delivery end AC system， this paper proposes an optimized voltage-dependent current order limitation control link （OVDCOL）. This paper firstly analyzes the working principle and limitations of the traditional VDCOL， and proposes to use the short-circuit ratio of the transmitting end and the voltage of the converter busbar at the receiving end as the input value to change the VDCOL cut-off voltage， so as to optimize the VDCOL effect. The cut-off voltage is a value that varies with the voltage of the converter busbar on the inverter side， and the control strategy of the system and DC fast recovery can be considered. The process of constructing the transient energy function considering the dynamic characteristics of the DC system is analyzed in detail， and the real-time digital simulation software RTDS is used to build a single-machine infinite DC simulation example. The time domain simulation and the transient energy function margin method are used to verify the optimized DC control. The voltage-dependent current order limitation control link in the system improves the stability of the delivery system.
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  Key Technologies of Operation and Maintenance of Electric Vehicle Charging Stations in Ubiquitous Power Internet of Things

  LIAO Jiaqi， QIAN Kejun， FANG Hualiang， ZHOU Chengke， XU Yan

  Electric Power Construction. 2019, 40(9): 20-26. https://doi.org/10.3969/j.issn.1000-7229.2019.09.003

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  With the current rapid development trend of electric vehicles， aiming at the shortcomings of operation and maintenance of charging stations， a method for developing the operation and maintenance strategy of electric vehicle charging stations in the electric internet of things is proposed. According to the equipment structure and operation characteristics of the charging station， the fault model of the key charging facilities is established； the extra time spent in the charging process is used as the risk index， the reliability analysis of the electric vehicle charging station is carried out， and the importance level of operation and maintenance of different stations is divided according to the risk value and the operation and maintenance plans is formulated. Taking an area of a city as an example， the real-time equipment failure model and the charging model of users are used to evaluate the reliability of each charging station and allocate the operation and maintenance time resources reasonably.
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  Communication Analysis of Information Collection Services in Smart Distribution System towards Ubiquitous Power Internet of Things

  SHEN Bo， CAI Zexiang， DAI Guanquan， GUO Caishan

  Electric Power Construction. 2019, 40(9): 27-34. https://doi.org/10.3969/j.issn.1000-7229.2019.09.004

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  The construction of Ubiquitous Power Internet of Things asks for more stringent requirements on the economy， security and reliability of the communication networks in distribution system. Therefore， a well-designed communication network architecture and configuration method is essential to address this issue. First， this paper proposes a communication network architecture for Ubiquitous Power Internet of Things. Then， the communication performance constraints of smart distribution services are analyzed. According to the characteristics of the information collection services， a communication bandwidth calculation method based on queuing theory is established， whose objective function is the maximum of bandwidth utilization. On the basis of a reconstruction project of a smart distribution station， the service delay， packet loss probability， bandwidth utilization and bandwidth configuration relationship for the information collection services are calculated. Finally， the feasibility of the proposed method is verified by the OPNET modeler platform， which reveals that the proposed method in this paper is technically practical.
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  Assessment Method for Grid-side Storage Demand under Multiple Application Scenarios

  ZHU Huan， CHENG Liang， CHEN Chen， ZHUO Zhenyu， CUI Bo， GONG Lijia， ZHANG Ning

  Electric Power Construction. 2019, 40(9): 35-42. https://doi.org/10.3969/j.issn.1000-7229.2019.09.005

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  As an excellent flexible resource， energy storage equipment plays an important role in multiple scenarios of system operation. In current grid-side storage planning research， there is a lack of assessment methods for the energy storage demand boundary under multiple application scenarios. On the basis of the operation history data and power system operation simulation method， this paper presents a storage demand assessment method for multiple scenarios. This paper applies the method to calculate the storage capacity demand under three scenarios： frequency regulation， peak regulation and smoothing renewable energy output for Jiangsu Power Grid. Among them， the demand for frequency regulation is 289.3 MW/134.2 MWh； the demand for smoothing renewable energy output is 389.6 MW/629.2 MWh and 636.8 MW/433.5 MWh； and the demand for peak regulation is 1 245 MW/1 680 MWh. Suggestions for the choice of storage types are also given.
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  Storage Control of Integrated Energy System for Integrated Demand Response

  ZHANG Yongxin， SHEN Hong， WEN Jun

  Electric Power Construction. 2019, 40(9): 43-51. https://doi.org/10.3969/j.issn.1000-7229.2019.09.006

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  Integrated energy system can achieve the efficient utilization of energy， and is of great significance in dealing with resource shortage and environmental pollution. Energy storage and integrated demand response are important means and functions of future integrated energy system. How to properly coordinate them has become a key issue in the theoretical research and engineering practice of integrated energy systems. Aiming at the specific control problem of energy storage equipment for integrated demand response， a model of the relationship between energy storage demand and energy storage control instructions is established on the basis of model predictive control. Then， a genetic algorithm is used to solve the optimal solution of control signal of the model. The simulation results demonstrate that the automated method proposed in this paper can make use of historical load data and prediction information to calculate the future control instructions of the energy storage equipment in advance， and ensure the high precision of the control output. While widening the application scope of energy storage， it can fully improve the energy utilization rate and economic benefits of integrated energy system.
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  The Strategy of Integrated Demand Response Considering the Interaction Between Distribution Grid and Industrial Park

  WANG Li,WU Guopei， ZENG Shunqi， HE Zhongxiao， DONG Shufeng

  Electric Power Construction. 2019, 40(9): 52-63. https://doi.org/10.3969/j.issn.1000-7229.2019.09.007

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  There is a lack of interaction mechanism of comprehensive response， which cannot accurately control and manage response resources according to the actual response potential of users. Therefore， this paper proposes an integrated demand response strategy considering the interaction between upper power grid and industrial park. Firstly， this paper proposes an interactive mechanism of integrated demand response in industrial parks， which clarifies the interactive way of information between energy systems. Secondly， a comprehensive demand response model is proposed， which consider peak-demand energy economy and user satisfaction. The branch and bound method is used to obtain the user controllable ability and corresponding demand response strategy. Meanwhile， according to the response scheme reported by user， the park energy management center obtains the user response combination scheme with the lowest overall compensation cost through the user optimization model. The numerical results show that the IDR strategy proposed in this paper can further tap the adjustable potential of users. In addition， the park energy management center can reasonably select users who will participate in the demand response according to the actual adjustable ability of them， and obtain the same peak regulation potential at lower demand response cost. This will be beneficial to realize the win-win between the user side and the Power Grid Corp.
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  Optimal Scheduling of Combined Cooling Heating and Power Microgrid Based on Demand Response and Multi-Energy Coordination

  YUAN Guili， DONG Jinfeng， WEI Geng， JIA Xinchao

  Electric Power Construction. 2019, 40(9): 64-72. https://doi.org/10.3969/j.issn.1000-7229.2019.09.008

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  Taking into account the multi-complementary power supply side and the load-side demand response （DR） is an important means to improve the coordination power generation capacity of the source and the load side， and can promote peak-shaving and valley-filling and increase economic benefits. In view of the problems of the randomness and mismatch of cooling， heating and power load， considering that human has certain adaptability to the temperature， this paper combines photovoltaic， wind power and  gas turbine combined cooling heating and power （CCHP）， and proposes a source-load coordinated CCHP microgrid based on DR. Under the typical scene， considering the uncertainty of new energy output， an optimal scheduling model is established. The model aims to minimize the economic cost， and is solved by immune genetic algorithm. The relationship between dispatching cost and different DR modes， temperature deviation is discussed， and whether the system introduces electric heating equipment is discussed. The analysis of the example shows that the optimal scheduling method based on DR and multi-energy coordination for CCHP microgrid can effectively reduce cost and has significant economic and social value.
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  Lightweight Key Management Scheme Based on Communication System of Electric Vehicle Charging Piles

  TAN Kai， LI Zhongwei， GUAN Yadong， YE Lin， TONG Weiming， ZHANG Baojun

  Electric Power Construction. 2019, 40(9): 73-81. https://doi.org/10.3969/j.issn.1000-7229.2019.09.009

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  As an important part of the communication network of ubiquitous power internet of things， the key management of charging pile communication system is important to the successful implementation of information security protection measure. In order to ensure the communication security of the three-tier architecture of backstage service management center， electrical control cabinet and electric vehicle charging piles， and to consider the efficiency of electric vehicle charging pile communication， a lightweight key management scheme （CPKMS） is proposed； The detailed implementation process of key generation， key issuance， key update and key destruction is proposed； Key security， forward and backward security， anti-attack capability， operation load and key storage quantity of CPKMS are analyzed. The analyzing results show that CPKMS can resist replay attack， forgery attack and man-in-the-middle attack. It has high security and efficiency， and can meet the safety requirements of the key management of electric vehicle charging piles.
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  Research on Scheduling Strategy of Data Centers Participating in Multi-peak-regulating Ancillary Service Markets

  LIU Yongjun， CAO Xiaojun， HU Zhaoyang， WANG Ke， XU Lizhong， GAO Ciwei

  Electric Power Construction. 2019, 40(9): 82-90. https://doi.org/10.3969/j.issn.1000-7229.2019.09.010

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  Data center electricity load is an adjustable resource with great application prospects on the load side. Cloud computing and big data technologies ensure that data centers can quickly transfer data loads from place to place through the network. At the same time， the development of technologies such as smart grid and automatic demand response makes it possible to quickly and automatically adjust the electricity load of data centers. At present， the power supply in China is generally surplus， and the peak regulation， especially the valley-load peak regulation， has become one of the difficult links in system operation and management. As a high-quality demand response resource， data centers can achieve the  power transfer between multiple electricity markets through data network， with a strong peak regulation potential. The demand response method of data centers participating in peak-regulating ancillary service markets is designed. The overall framework of data network participating in multi-peak-regulating ancillary service markets is proposed. And the scheduling strategy of data network participating in peak-regulating ancillary service markets is established. The example shows that the optimal scheduling scheme of the model can ensure the efficiency and economy of data centers when participating in multi-peak-regulating ancillary service markets.
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  The Content， Frameworks and Key Technologies of Power Internet of Things for Urban Energy Internet

  GE Leijiao， WANG Yuqian， QI Jiaxing， WANG Hui，LIN Qiang， PENG Ying

  Electric Power Construction. 2019, 40(9): 91-98. https://doi.org/10.3969/j.issn.1000-7229.2019.09.011

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  The power internet of things （IOT） is the important foundation to ensure the safe， reliable， economical and efficient operation of the power system， and also a basic platform to support the urban energy internet. In this paper it makes a deep discussion and analysis on the content， frameworks and key technologies of the power internet of things for urban energy internet. Firstly， the differences between the urban energy internet and the power internet of things are sorted out and analyzed， and the content of the power internet of things oriented to the urban energy internet is proposed and the framework， physical framework and system framework of power internet of things for urban energy internet are proposed. Finally， combined with cloud computing technology， big data， internet of things， mobile internet， power fiber to the home， four-network convergence of telecommunication network， internet， broadcast network and power grid， and three-meter collection of water， electricity and gas， this paper elaborates the content and existing shortcomings of the key technologies of the power IOT for urban energy internet from the perspectives of information and communication， wishing to provide some reference for the future development and research of urban energy internet.
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  Phase-Angle Stability Analysis of Microgrids in Electromagnetic Time Scale

  WANG Rui， SUN Qiuye， ZHANG Xuemeng， MA Dazhong

  Electric Power Construction. 2019, 40(9): 99-106. https://doi.org/10.3969/j.issn.1000-7229.2019.09.012

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  With the large-scale integration of distributed renewable energy into power grid， synchronous oscillation and harmonic instability have attracted more and more attention. Compared with the traditional power system， the microgrid has plenty of characteristics， such as negative impedance， low inertia， negative damping and bidirectional power flow. Consequently， this paper proposes a phase stability analysis method based on small-signal modeling in electromagnetic time scale. Firstly， the small-signal modeling of power converter is established， and the phase stability of power converter is obtained by the inherent relationship between system phase angle and reactive power of distributed generation. Furthermore， the closed-loop transfer function of the power converter is established， and the phase stability region is obtained through eigenvalue analysis. Eventually， the proposed phase angle stability method in electromagnetic time scale is verified by simulation and experiment results.
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  Optimization of Floating Charging Service Fee  Based on the Prospect Theory for Quantifying Charging Utility

  CAO Fang， LI Sai， ZHANG Yao

  Electric Power Construction. 2019, 40(9): 107-115. https://doi.org/10.3969/j.issn.1000-7229.2019.09.013

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  Guiding the charging behavior of electric vehicles （EVs） through price means helps to reduce the adverse effects of a large number of EVs access to the power system. This paper proposes an optimization model for floating charging service fee to guide EV users to charge more reasonably. Firstly， EV users are classified according to user preference. And on this basis， users charging utility model based on prospect theory is established. Secondly， the transfer probability matrix is used to establish the price response model of EV users. Then comprehensively considering the interests of the grid， charging stations and users， a multi-objective optimization model is established for floating service fee. Finally， the multi-objective particle swarm optimization algorithm is improved on the basis of adaptive grid archiving by non-uniform mutation operation and the model is solved by using the proposed algorithm. Taking a typical urban area as an example， the optimization results of floating service fee under different base loads， the user price response results under different service fee mechanisms and the user response behavior under different user compositions are compared and analyzed. The correctness and effectiveness of the mechanism and model described in this paper are verified. The results of these examples show that the floating service fee mechanism and its optimization model mentioned in this paper can further guide the charging behavior based on the time-of-use electricity price mechanism and play the role of cutting peak and filling the valley as well as ensuring the interests of all aspects.
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  Demand  Response Pricing Model for Power Sales Companies Considering User Differences

  WANG Xinghua， LIU Shengwei， CHEN Haojun， PENG Xiangang， ZHOU Yawu

  Electric Power Construction. 2019, 40(9): 116-123. https://doi.org/10.3969/j.issn.1000-7229.2019.09.014

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  With the liberalization of the power sales market， a large amount of social capital has entered the market， and the number of power sales companies has increased dramatically. In the fierce market competition， how to ensure the self-revenue and improve the users power consumption satisfaction is an urgent problem for sales companies. For this reason， a power pricing strategy based on different power consumption of power users is constructed. Firstly， according to the load curve， the similarity and difference of different users behavior are analyzed and then the user is subdivided. A customized time-sharing electricity price model is established to obtain the optimal pricing strategy for the sales company and its users to maximize revenue. Finally， the model is solved by the genetic algorithm and the cross-section algorithm applying to the actual load data of the power users， and the effectiveness of the proposed electricity price decision model is proved.
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  Optimal Operation of Wind-PV-ES Joint System Considering the Peak Regulation Capability

  YANG Pengpeng，ZHANG Xiuping，WANG Mingqiang，YANG Ming，ANG Fei，WANG Shibo

  Electric Power Construction. 2019, 40(9): 124-130. https://doi.org/10.3969/j.issn.1000-7229.2019.09.015

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  Photovoltaic （PV） and wind power （WT） integration incur the deficiency of power regulation resource， which limits the renewable energy accommodation into power system. Research on negative peak-regulation capability at valley-load level has significant importance. In this paper， the effect of time complementary between PV and WT on peak regulation is analyzed， and two extreme scenarios of peak regulation demand increase which is caused by the renewable energy integration are introduced. A scheduling model of wind-PV-ES joint system is proposed which is aimed to maximize the negative peak-regulation capability during valley-load level. The effectiveness of the proposed model is verified by an actual provincial power system in North China. The result indicates that the joint operation of WT， PV and energy storage （ES） can significantly release the pressure on peak-regulation capacity requirement， and promote the integration of renewable energy generation.