ISSN 1000-1026
CN 32-1180/TP
  • ISSN 1000-1026
  • CN 32-1180/TP

Volume 43,Issue 10,2019 Table of Contents


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Cyber Energy Systems
A Review on Research of Cyber-attacks and Defense in Cyber Physical Power Systems: Part Two Detection and Protection
TANG Yi, LI Mengya, WANG Qi and NI Ming
2019, 43(10): 1-9.DOI: 10.7500/AEPS20180906007
[Abstract](237)[HTML](0)[PDF 1.49 M](155)
Following the previous paper in the series, this paper provides a review of existing research methods on the sub-topics of attack detection and defense strategy. The purposes and natures of research work of the sub-topics are concluded, and the deficiencies of existing researches are described considering the characteristics of cyber physical power system(CPPS). In terms of attack detection, some methods are proposed based on deviation and feature, which are implemented in cyber and physical sides in CPPS. In terms of protection, existing researches are concluded as the protection methods deployed on cyber side which are mainly reactive protection measures, and the protection methods deployed on physical sides which are mainly based on the ideas of redundant resources and corrective control. On the basis of existing research, the key techniques in CPPS cyber-attack detection and defense are drawn, and future research proposals in these fields are made in accordance with research perspective of modeling, in order to improve the real ability of CPPS to defend itself against cyber-attacks.
Optimal Economic Scheduling for Multi-microgrid System with Combined Cooling, Heating and Power Considering Service of Energy Storage Station
WU Shengjun, LIU Jiankun, ZHOU Qian, WANG Chenggen and CHEN Zhe
2019, 43(10): 10-18.DOI: 10.7500/AEPS20181024001
[Abstract](178)[HTML](0)[PDF 1.88 M](168)
A day-ahead optimal scheduling method for combined cooling heating and power(CCHP)multi-microgrid system considering energy storage station service is proposed. Firstly, the public energy storage station is built in the multi-microgrid system, and the service mode for the energy storage station on the user side is proposed. Then, the energy storage station service is applied to the optimal economic schedule of CCHP multi-microgrid system. The power balance and operation cost of the cooling load, heating load and power load in microgrids are optimized by coordinating the interactive power between energy storage station and microgrids. Finally, three operation modes of CCHP multi-microgrid system under the typical scenarios are carried out to analyze the optimal economic scheduling. Numerical studies demonstrate that the proposed optimal scheduling method can effectively improve the operation flexibility of the public energy storage station, realize time-domain transfer of the excess energy of microgrids and consume the renewable energy generation by 100%, while reduce the operation costs of CCHP multi-microgrid system.
Basic Research
Adequacy Optimization for a Large-scale Renewable Energy Integrated Power System Part Two Collaborative Optimization of Multi-grade Reserve
WU Jun, XUE Yusheng, SHU Yinbiao, XIE Dongliang, SONG Xiaofang and XU Yan
2019, 43(10): 19-26.DOI: 10.7500/AEPS20181023002
[Abstract](280)[HTML](0)[PDF 2.25 M](192)
With the gradual increase of the intermittent renewable energy generation, the demand of system reserve capacity is raised accordingly. The pure use of spinning-grade reserve for supporting reserve capacity to the system will not only cause economic problems, but also lead to high CO2 emission from long-term maintenance of high proportion of spinning-grade reserve, which violates the original intention in developing renewable energy generation. The use of flexible non-spinning-grade reserve will provide standby service and have great help to improve the adequacy of the system, which is an important way to promote the consumption of renewable energy. Aiming at the inadequacy of current optimization research in non-spinning-grade reserve, firstly, the dispatch mode and optimization model for non-spinning reserve on both the generation side and demand side are analyzed under the market mechanism. Then, a hybrid optimization method considering the differences and complementarities of spinning-grade and non-spinning reserve is proposed under multiple adequacy scenarios. Finally, detailed case studies verify the feasibility and effectiveness of the proposed optimization method.
Joint Planning of Generalized Energy Storage Resource and Distributed Generator Considering Operation Control Strategy
CHENG Lin, QI Ning and TIAN Liting
2019, 43(10): 27-35.DOI: 10.7500/AEPS20180814004
[Abstract](372)[HTML](0)[PDF 1.74 M](484)
Aiming at the joint planning problem of generalized energy storage resources and distributed generator, a response model including fixed energy storage, shiftable load, transferable load and reducible load is proposed. Furthermore, the joint planning problem of generalized energy storage resources and distributed generator considering operation control strategies is solved by a bi-level optimization architecture. The practical significance and methods of siting and locating of different regulatory resources are put forward. The upper layer uses improved multi-objective particle swarm optimization algorithm to search the location and capacity selection scheme. The lower layer uses branch and bound method to solve the operation control strategy of generalized energy storage. The joint optimization configuration of resources is implemented by alternate optimization of upper and lower levels. The simulation results of multi-scenario in IEEE 33-node distribution system verify the practicability of the proposed model and prove the advantages and significance of joint planning and operation control of the virtual energy system.
Impact Evaluation of Operation Strategies of Multiple Energy Storage Systems on Reliability of Multi-energy Microgrid
LIU Hong, LI Jifeng, GE Shaoyun, ZHANG Peng, SUN Hao and WANG Yiran
2019, 43(10): 36-43.DOI: 10.7500/AEPS20180313006
[Abstract](152)[HTML](0)[PDF 1.53 M](135)
In view of the research background that the effect of energy storage on the reliability of energy supply is still to be excavated, the effect of multiple energy storage on the reliability of energy supply is quantitatively analyzed by formulating different operation strategies of energy storage link and combining relevant reliability indices. Firstly, taking the multi-energy microgrid as the research object, the energy efficiency model of key device is constructed. Secondly, different operation strategies for the energy storage devices are formulated, and the corresponding indicators are sorted out to analyze the characteristics of energy storage device and the impact on the system reliability. Finally, the effect of different configuration of energy storage devices and different operation strategies on the reliability of energy supply system are analyzed quantitatively by actual examples. This paper focuses on the analysis of the impact of the energy storage link of multi-energy microgrid on the reliability of energy supply system, thus providing guidance for the planning of energy storage device.
Global Sensitivity Analysis for Islanded Microgrid Based on Sparse Polynomial Chaos Expansion
WANG Han, YAN Zheng, XU Xiaoyuan and HE Kun
2019, 43(10): 44-52.DOI: 10.7500/AEPS20180625006
[Abstract](125)[HTML](0)[PDF 1.50 M](111)
As the penetration rate of renewable energy sources and the proportion of electric vehicles continue to increase, the uncertainties in the operation of microgrids have increased significantly. Accurate assessment of the influence of uncertainties on the status of microgrids will help improve the safe and stable operation of the system. Considering the uncertainties of source and loads, the probabilistic power flow model of islanded microgrids is established and the global sensitivity analysis indices are introduced. Then, the global sensitivity analysis of islanded microgrids based on sparse polynomial chaos expansion is proposed. The proposed method is used to accurately and quickly identify critical input random variables that affect the operation status of the system. Through the simulation of a 40-bus islanded microgrid with distributed generators, the accuracy and efficiency of the proposed method are verified. The effect of the source and load uncertainty on the power flow of islanded microgrid is analyzed and the importance ranking of input random variables is given.
Control Strategy of Coordination and Equalization for Diesel Generator and Energy Storage System in Emergency Microgrid
ZHAO Zishan, MENG Zhiquan, ZHANG Junfeng, HE Xiaoliang, JIANG Feng and XIN Huanhai
2019, 43(10): 53-59.DOI: 10.7500/AEPS20180730011
[Abstract](100)[HTML](0)[PDF 1.75 M](87)
The emergency microgrid can provide emergency power supply to the distribution networks when large-area blackout occurs. But the emergency microgrid is temporarily established, with poor communication conditions, changeable working conditions and frequently plugged and unplugged mobile emergency power sources. The coordination and equalization control strategy for the emergency microgrid is proposed, in which energy storage systems and diesel generators are used as the main power supply. Besides the primary droop control and the secondary control for frequency and voltage recovery, the control strategy adds the auxiliary equalization control based on multiple time scales. The equalization control of diesel generators can adjust the stable operation point based on the feedback frequency control signal in order to correct the speed measurement error and equalize the output of each power source. And the equalization control of energy storage systems can realize state of charge(SOC)balance by dynamically adjusting the droop slope based on the deviation of SOC. The control strategy does not rely on central controller of microgrid to facilitate quick emergency power supply. Finally, simulation results verify the feasibility and effectiveness of the proposed control strategy.
Secondary Regulation Strategy for Islanded Microgrid Based on Model Predictive Control
LI Demin, WU Zaijun, ZHAO Bo, ZHANG Xuesong and ZHANG Leiqi
2019, 43(10): 60-67.DOI: 10.7500/AEPS20180710002
[Abstract](144)[HTML](0)[PDF 1.49 M](104)
Due to the influence of line impedance, the conventional P-f and Q-V droop control cannot realize the target of accurate reactive power sharing proportional to their rated capacity and the output voltage amplitudes of all distributed generators(DGs)deviate from nominal voltage. The frequency cannot be maintained at the rated frequency value when load fluctuates. A secondary regulation strategy based on model predictive control(MPC)is proposed. By optimizing the frequency and voltage references of droop control, respectively, the frequency and average system voltage are always maintained at their respective nominal values. Meanwhile, the target of accurate reactive power sharing proportional to their rated capacity is realized and the output voltage amplitude deviation from nominal voltage is reduced. The state-space model of DG is discretized with a certain sampling period in this strategy. The control variables of frequency and voltage are obtained by rolling optimization and feedback correction and then added to P-f and Q-V primary controls, respectively, to realize the secondary regulation for frequency and voltage optimization. The number of proportional-integral(PI)control parameters decreases and the sensitivity to the system parameters is reduced. The MATLAB/Simulink simulation verifies that the proposed strategy has faster transient response characteristics and stronger robustness when load fluctuates compared with the PI based secondary regulation strategy.
Compound Balancing Control Strategy of SOC for Battery Energy Storage System Based on Cascaded H-bridge Converter
LIU Chang, CAI Xu and CHEN Qiang
2019, 43(10): 68-77.DOI: 10.7500/AEPS20180917002
[Abstract](114)[HTML](0)[PDF 1.33 M](48)
A novel compound balancing control strategy of state of charge(SOC)combining injection of zero sequence voltage and negative sequence voltage is proposed to address the issue of SOC unbalance between phases in battery energy storage system based on cascaded H-bridge converter, which is on the basis of detailed analysis of the power model of the system. The output performance of the device, interphase SOC balancing capability and power quality are all taken into account in this strategy. The process of SOC balancing can achieve smooth transition and has no disturbance to the system. The operation results of experimental prototype verify the validity and effectiveness of the proposed control strategy.
Risk Dispatch of Power System Considering Second-life Batteries as Flexible Loads
HU Shubo, SUN Hui, SUN Qizhong, PENG Feixiang, ZHOU Wei and SUN Jingjie
2019, 43(10): 78-86.DOI: 10.7500/AEPS20180806010
[Abstract](109)[HTML](0)[PDF 1.38 M](48)
The centralized utilization of batteries retired from electric vehicles(EVs)can be a new kind of flexible loads participating in power dispatch. The operation and output characteristics of second-life batteries are studied based on the experiment data. A risk power dispatch model with second-life batteries as flexible loads considering the discordance risk of retired batteries and the error risk of second-life batteries and wind generators is built. The model aims at the minimum operation cost and risk of the system and the second-life batteries is utilized to reduce the peak valley difference of power load and the fluctuation of the power system and save energy. The simulation results on a ten-unit test system have certified the effectiveness of the proposed dispatch model and the economic benefit of utilizing second-life batteries as flexible loads.
Virtual Inertia Control Strategies for Double-stage Photovoltaic Power Generation
YANG Huibiao, JIA Qi, XIANG Li, YAN Gangui, ZHANG Shanfeng and LI Xutao
2019, 43(10): 87-94.DOI: 10.7500/AEPS20180812001
[Abstract](159)[HTML](0)[PDF 1.44 M](81)
Large-scale grid-connected photovoltaic(PV)generation has an important effect on synchronous generators with rotational inertia, which causes the problem of insufficient inertia and insufficient frequency modulation capability. Therefore, there is an urgent need for PV generation to take part in frequency regulation. Taking the two-stage PV power generation as the research object, the conventional virtual inertia control based on the dynamics of the phase locked loop(PLL)is studied. At the same time, the virtual inertia control based on the dynamics of the low-voltage DC capacitor and the virtual inertia control based on the dynamics of the high-voltage DC capacitor are proposed, and the influence of control parameters of virtual inertia control is analyzed. The results show that: (1) in the case of conventional virtual inertia control, the narrower PLL control bandwidth is, the more PV power can be provided during the process of frequency sag; (2) in the case of virtual inertia control based on low-voltage DC capacitor dynamics, owing to the introduction of f-UPV compensation in the voltage control loop, the change of low DC voltage affects not only the frequency dynamic process but also the steady-state frequency deviation; (3) in the case of virtual inertia control based on high-voltage DC capacitor dynamics, PV generation can provide more power in the case of frequency sag, when the integral coefficient of the Boost converter voltage control loop rises to slow down the dynamic response of the DC voltage.
Bi-level Optimization Model of False Data Injection Attack for Power Grid
SHU Jun, GUO Zhifeng and HAN Bing
2019, 43(10): 95-100.DOI: 10.7500/AEPS20180420001
[Abstract](127)[HTML](0)[PDF 1.24 M](54)
With the development of smart grid technology and information technology in recent years, the possibility of cyber attacks in power system increases. A bi-level nonlinear optimization model of false data injection(FDI)attack is proposed based on the state estimation. In the upper level, the cyber attackers hack the measurement data of the power system with the purpose of finding the optimal attack strategy to maximize the economic loss of the power system while subjected to a list of constraints including the measuring attack range and state estimation residual error. The security-constrained economic dispatch model is used in the lower level and the power system operators perform the optimization dispatch of power system based on the load data disposed by the state estimation. In order to handle the complexity of the bi-level optimization model, the proposed model is transformed to single-level nonlinear planning model with KKT(Karush-Kuhn-Tucker)conditions. The programming simulation of nonlinear FDI attack model is implemented in GAMS and solved by using the nonlinear planning solver of BARON. The numerical results indicate that the bi-level FDI optimization attack could seriously deteriorate the secure and economic operation of power systems, and the effectiveness of the proposed approach is consequently validated.
Fault Detection Algorithm for Transmission Lines Based on Random Matrix Spectrum Analysis
TONG Xiaoyang and YU Senlin
2019, 43(10): 101-108.DOI: 10.7500/AEPS20180602002
[Abstract](158)[HTML](0)[PDF 1.44 M](100)
Considering the lack of anti-interference ability of fault detection algorithm based on the fundamental wave phasor system and similarity of time-domain waveform, a novel transmission line fault detection algorithm based on random matrix spectrum analysis is proposed. Firstly, using the almost reverse characteristics of waveforms for the current fault components at both ends of the line, the original matrix is formed by a fixed time window that consists of current fault component on one side and opposite current fault component on the other side. A random matrix is constructed by copying, translating, and adding noise, its mean spectral radius is calculated and spectrum analysis is taken, which brings about two criteria of fault detections for lines. Then, the single ring theorem of the theory for random matrix is used to set the threshold and the influence of various factors on the proposed algorithm is analyzed. Finally, a large number of simulation examples in the IEEE-39 bus system prove the effectiveness of the algorithm. The simulation results show that the algorithm is not affected by the fault location, non-full-phase operation and heavy load and it will not cut off the normal line when the system oscillates. It also has a strong ability of resisting the transition resistance and does not require high information of synchronization.
Application Research
System-level Control Strategy for UPFC Power Grids Integrated with UHVDC
YANG Jian, SONG Pengcheng, XU Zheng, CAI Hui and XIE Zhenjian
2019, 43(10): 109-117.DOI: 10.7500/AEPS20180916005
[Abstract](206)[HTML](0)[PDF 1.32 M](85)
To alleviate the problem of line overload raised by the integration of ultra-high voltage direct current(UHVDC)transmission systems, and to enhance the voltage support strength of the AC bus of the UHVDC station, the sensitivities of line loads and AC bus voltage magnitudes to the control of unified power flow controller(UPFC)are deduced based on electrical network theories. Then, the feasibility of the active/reactive power flow control ability of the series converter and the reactive power control ability of the shunt converter to achieve line overload control and voltage regulation is analyzed. On this basis, a UPFC control strategy for power grids integrated with UHVDC is developed. Using this control strategy, the system-level settings of the UPFC are generated automatically based on current/voltage measurements. Finally, a case study is done in the Suzhou southern power grid of China, where the 500 kV UPFC project and Jinping-Sunan UHVDC transmission system are located. The effectiveness of control sensitivity analysis and the feasibility of proposed control strategy are verified in the case study.
Improved Negative Sequence Directional Element for Transmission Line Connecting DFIG
YANG Qifan, LIU Yiqing, ZHU Yiming and CHEN Guobin
2019, 43(10): 118-126.DOI: 10.7500/AEPS20180816001
[Abstract](115)[HTML](0)[PDF 1.48 M](92)
Negative sequence directional element is widely used in the pilot protection of transmission lines. With the rapid development of wind power generation, a large scale of doubly-fed induction generator(DFIG)is connected to the grid and the negative sequence equivalent impedance of power source is no longer fixed, which destroys the theoretical basis of the traditional negative sequence directional element. This paper derives the analytic expressions of the negative sequence equivalent impedance of DFIG under two situations, which are the uninterrupted control by the rotor-side converter and the crowbar resistance being thrown into, respectively. Subsequently the change rules of phase angles of negative sequence equivalent impedance have been obtained under two situations. It has been found that the traditional negative sequence directional element faces the problems of sensitivity and reliability due to the influences of DFIG. Therefore, an improvement measure of the negative sequence directional element has been proposed as follows: before faults, the maximum sensitivity angle under different operation states is determined by DFIG parameters in the mode on line; after faults, the action criterion with higher sensitivity and reliability is adopted according to DFIG operation states. Digital simulation results show that the improved negative sequence directional element has higher sensitivity and can be well adapted to various operation states of DFIG.
Fault Location Method of Wind Farm Collection Line Based on Vector Deviation Degree
ZHANG Ke, SUN Lizhi, ZHU Yongli and LIU Xuechun
2019, 43(10): 127-133.DOI: 10.7500/AEPS20180417004
[Abstract](108)[HTML](0)[PDF 1.31 M](79)
In order to solve the problem of wind curtailment and poor power transmission ability caused by short-circuit faults in wind farm collection lines, a fault location method for wind farm collection lines based on vector deviation is proposed. According to the electrical information of each terminal measurement device, the objective function of vector deviation between the theoretical calculation value and the real measurement value is constructed by using total vector error(TVE)and total three-phase unbalance. According to the calculation results of deviation degree, the difference between the information of real fault and imaginary fault interval is judged. The imaginary fault interval corresponding to the minimum difference is the real fault interval. PSCAD/EMTDC simulation results show that the proposed method is feasible for different fault locations, different fault intervals and different transition resistances, and can meet the requirements of wind farm for the accuracy of collection line fault location.
Electrical Characteristics of Medium-voltage Distribution Network with Single-phase-to-ground Fault After Arc Extinction
YANG Fan, LI Guang, SHEN Yu, XUE Yongduan, PENG Hui and XU Bingyin
2019, 43(10): 134-141.DOI: 10.7500/AEPS20180911007
[Abstract](117)[HTML](0)[PDF 1.96 M](70)
The electrical variation law of the single-phase-to-ground fault in distribution network after arc extinction do not only determines the over-voltage level whether the arc is re-ignited or the re-ignition electrical characteristics, but also affects the adaptability and reliability of the fault diagnosis method. The system fault recovery process is analyzed based on the single-phase-to-ground fault equivalent circuit of distribution network. It is found that the zero-sequence network in different grounding systems have an attenuated oscillation process after arc extinction. For ungrounded system, the zero-sequence voltage amplitude is large. The oscillation frequency is much lower than the power frequency and the oscillation time is long. The phase overvoltage will last for a long time. For arc suppression coil grounding system, the zero sequence voltage amplitude is large. The oscillation frequency is slightly larger than the power frequency, and the duration is generally above 5 cycles. The beat frequency phenomenon will cause overvoltage whose amplitude is within 1. 1 times of the normal level on the fault phase. For low resistance grounding system, the oscillation frequency is much higher than the power frequency. Its amplitude is small and the attenuation speed is fast. The correctness of the recovery process of single-phase-to-ground fault after are extinction in three types of grounding systems is verified by ATP-EMTP.
Single-phase-to-ground Fault Arc-extinguishing Method for Distribution Network Based on SVG Two-phase Current Injection
ZHOU Xingda, LU shuai, CHEN Yangming, LIANG Shibin and WU Shengbing
2019, 43(10): 142-149.DOI: 10.7500/AEPS20180811005
[Abstract](108)[HTML](0)[PDF 1.32 M](80)
According to the single phase-to-ground fault in the medium-voltage distribution networks, a two-phase current injection method based on the cascaded H-bridge static var generator(SVG)is studied. When the distribution network is operating normally, the SVG works in the reactive compensation mode. When single-phase-to-ground fault occurs, the neutral point of SVG is grounded and the arc suppression currents are injected into the distribution network from the other two non-grounded phases bridge of SVG, so that the fault current at the grounded point is reduced, and the traditional arc suppression coil is replaced by reusing the existing SVG equipment. This paper discusses the relationship between current injection method of SVG arc suppression and the voltage balance control of SVG DC side and the working mode of two-phase current injection of SVG arc suppression and the design method of arc suppression controller are analyzed in detail. Then, its operation mode and the controller design process are discussed in detail. A 10 kV simulation model based on MATLAB/Simulink and an experimental prototype with 380 V three-phase four-cascade low-voltage SVG are constructed for simulation and experimental verification. The simulation and experimental results verify the correctness and feasibility of the proposed scheme.
Calculation Method of Transient Overvoltage Due to DC Blocking Based on Short Circuit Ratio of Reactive Power
YIN Chunya, LI Fengting, ZHOU Shiyuan and CHEN Weiwei
2019, 43(10): 150-154.DOI: 10.7500/AEPS20181114006
[Abstract](126)[HTML](0)[PDF 1.36 M](96)
The existing calculation methods of transient overvoltage on the commutation bus due to the ultra-high voltage direct current(UHVDC)blocking have no real solution in the case of extremely low short-circuit ratio. Based on the resonant circuit after DC blocking, this paper deduces and establishes the expression of the relationship between transient overvoltage and resonant frequency. Referring to the definition of short circuit ratio, the concept of reactive power short-circuit ratio is proposed. Then, a method for calculating transient overvoltage after DC blocking is proposed with wider application range. It is found that the trend of transient overvoltage on the commutation bus is nonlinear and accelerates with the decrease of reactive power short circuit ratio. Finally, based on the DIgSILENT simulation platform, the DC transmission standard test system of International Council on Large Electric Systems and Xinjiang Tianshan-Zhongzhou DC transmission system of China are built to verify the proposed calculation method of transient overvoltage. The simulation results show that the proposed calculation method is effective and applicable in the system with extremely low short-circuit ratio.
Static Security Analysis of AC/DC Power System with Multi-terminal Flexible DC
LI Yan, TENG Yun, LENG Ouyang, WANG Yi and LU Juanjuan
2019, 43(10): 155-161.DOI: 10.7500/AEPS20180910006
[Abstract](135)[HTML](0)[PDF 1.30 M](125)
The work principle and control mode of the multi-terminal DC system with voltage source converter(VSC-MTDC)are essentially different from the conventional DC system. The current static security analysis cannot directly analyze and calculate the AC/DC system with VSC-MTDC. Firstly, a calculation framework for AC/DC static security analysis of VSC-MTDC/AC hybrid system is proposed based on the traditional static security analysis of AC system, the adopted functional realization method and key technologies are described. Then, in the calculation of expected faults, the change of operation conditions of AC and DC power grids is taken into account to ensure that the calculation results are consistent with the actual operation conditions of power grids, which improves the accuracy of static security analysis and calculation. Finally, hybrid AC/DC system with four-terminal flexible DC system is established to verify the efficiency and practicability of the proposed method.
Egineering Application
Partition Method for Restoration of Asynchronous Receiving End Power Grid with Multi-infeed HVDC
YANG Chao, LIANG Haiping, GU Xueping, TANG Xiaojun, XIE Yan and LIU Yumeng
2019, 43(10): 162-170.DOI: 10.7500/AEPS20180604011
[Abstract](119)[HTML](0)[PDF 1.32 M](50)
Aiming at the restoration problem of asynchronous receiving end power grid, a partition method for system restoration is proposed, which considers the structure characteristics of network community and the interaction between AC and DC system. Firstly, on the basis of analyzing the interaction, the system strength indices are added to the partition principle and constraints, and the optimal transmission power of each line commutated converter based high voltage direct current(LCC-HVDC)system is obtained by solving the corresponding optimization model. Then, a partition model is proposed for the asynchronous receiving end power system restoration. Secondly, by taking the comprehensive influence on the bus short-circuit capacity of each HVDC dropping location as the weight, the weighted edge betweenness of branch circuit is defined. The partition number can be automatically determined according to the partition constraints and the number of black start sources. An improved GN splitting algorithm is then used to realize the reasonable partition of the multi-infeed HVDC receiving end power grid. Based on the partition results, the restoration time and load restoration capacity are calculated. Finally, the partition results of the IEEE 39-bus system and a local power grid in a southern province of China verify the feasibility and effectiveness of the proposed method.
Flexible Combination Control Strategy for Control Area of Provincial AGC in Regional Power Grid
NING Jian, TAN Chao, JIANG ChangMing, TENG Xianliang, NIU Siqing and ZHANG Yong
2019, 43(10): 171-176.DOI: 10.7500/AEPS20180907004
[Abstract](176)[HTML](0)[PDF 1.45 M](122)
To solve the problem of inadequate reserve of provincial control areas during special periods such as peak load regulation or accident disposal, the structure and strategy of flexible combination control for provincial areas is proposed. Regional power grid dispatch center flexibly selects provincial control areas to participate in joint control according to the principles such as reserve sharing in adjacent areas. Firstly, based on the existing boundary model of provincial control areas and area control error(ACE)calculation mode, automatic generation control(AGC)in regional power grid calculates the ACE of each sub-control area and then quickly obtain the ACE of the combined control area by superposition. Secondly, based on the uploaded information such as real-time reserve of provincial grid and considering factors of minimum reserve, frequency deviation coefficient and actual adjustable reserve, ACE of the combined control areas is distributed optimizedly to provincial grids for execution after grid security check of provincial(inter-provincial)sections. The goal of breaking the provincial barriers for reserve sharing and emergency support in case of accidents is achieved while reducing the unnecessary reverse regulation of control areas. The effectiveness of the control strategy is verified through the actual operation.
Overview of Charging and Discharging Load Forcasting for Electric Vehicles
CHEN Lidan, ZHANG Yao and Antonio FIGUEIREDO
2019, 43(10): 177-191.DOI: 10.7500/AEPS20180814001
[Abstract](199)[HTML](0)[PDF 1.51 M](186)
The adoption rate of electric vehicles(EVs)will considerably increase based on the continuous promotion of EVs and the gradual construction of charging infrastructures. The spatio-temporal distribution prediction of EVs charging load is the basis for the research related to the integration of EVs into the power grid. The key factors of EVs charging load are firstly investigated. Three aspects are considered at the micro level, which are the characteristics of EV, charging facility relevant factors and EV user behavior-related. At the macro level, three main components are addressed in terms of policy, environment and market. Secondly, the paper provides a summary of previous work regarding modeling of spatio-temporal EV charging, where the uncertainties of user behavior are discussed in detail. The application of some new technologies in the current research is presented. Moreover, the research status of EVs participation in discharging potential assessment is delivered. Finally, research gaps that need to be further explored are identified.

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