LOW VOLTAGE APPARATUS

Analysis on Development of Energy Storage Technology from Perspective of Energy Security

YIN Guangzhi, ZHENG Zhanghua, WANG Xin, ZHU Jiahui

2022, 0(5): 1-7. doi:10.16628/j.cnki.2095-8188.2022.05.001

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The large-scale integration of renewable energy has become an important way to achieve China’s carbon neutrality goal,and te deployment of energy storage equipment is an important guarantee for this path.In the past decades,China has achieved huge success in the adopting pumped storage hydropower and the lithium battery as the most important energy storage equipment.However,with the increasingly politicized climate change and the increasingly “de Sinicization” of the industrial chain of developed countries,as a country with high external dependence on the lithium resources,there are certain risks for China to continue the energy storage development path dominated by the lithium batteries.From the perspective of energy security,China should consider supporting the energy storage technologies with the high resource self-sufficiency rate,so as to better ensure the realization of the double carbon goal.

Research on on-Board Energy Storage System Based on Drive Multiplexing Topology Under Distribution Network

ZHOU Yi, YUE Yunli, YUE Hao, DING Jianmin, LI Shunxin, XIN Dixi

2022, 0(5): 8-16. doi:10.16628/j.cnki.2095-8188.2022.05.002

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Electric vehicle charging technology has been developed in the long run with the increasing popularity of electric vehicles.The on-board energy storage system is attracting the attentions due to the plug-and-play nature,which do not require the support of the charging piles.Among these, the on-board energy storage converter based on the driving multiplex motor and the driving converter has been widely studied in recent years due to the high system integration and power density.The researches on the topologies of the driving multiplex on-board energy storage systems are induced,and the advantages and disadvantages of each topology are summarized.The analysis method of torque and ripple is put forward,which is key indicators for driving multiplex on-board energy storage system during charging.The various topology schemes are compared based on these relevant indicators.

Research on Engineering Design of Station DC Backup Power System Based on Lithium Iron Phosphate Battery

CAO Bin, RAO Chengcheng, LUO Wei, LIU Yuxiang

2022, 0(5): 17-22. doi:10.16628/j.cnki.2095-8188.2022.05.003

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At present the lead-acid battery is widely used as the backup power of station DC system,but it has some inherent defects.The research of station DC backup power to replace the lead-acid battery with lithium iron phosphate battery is of great significance to comprehensively improve the reliability and safety of DC power system.Based on the 220 V DC backup system for the 220 kV substation,the design of lithium iron phosphate battery DC power system is put forward,including the basic function,the parameter design and the small capacity multi-channel parallel electrical topology.The group mode of lithium battery and the parameter design of battery management system (BMS) are further analyzed.Finally,based on the special charge and discharge characteristics of lithium iron phosphate battery,the charge and discharge strategy,capacity verification and maintenance strategy and the BMS system alarm protection strategy suitable for the lithium iron phosphate battery are studied,which can provide design basis and research basis for the implementation of the lithium electrification substitution transformation of the station lead-acid battery.

Research on Comprehensive Evaluation Method of Battery Consistency in Energy Storage Power Station

JIN Wentao, LI Yuyang, JIA Xuecui, LI Xiangjun

2022, 0(5): 23-28. doi:10.16628/j.cnki.2095-8188.2022.05.004

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The construction of new energy storage in China is advancing at a high speed.The health state of the energy storage power station is affected by the operating conditions and environment.Each battery unit will be inconsistent in varying degrees,which will affect the operation safety of the power station.By analyzing the voltage and temperature deviation of the energy storage single battery under different operating conditions,combined with the average voltage,range voltage,voltage standard deviation,voltage variation coefficient,range temperature and maximum temperature index parameters of the single battery,a comprehensive evaluation method for the consistency of the energy storage single battery is put forward by the using analytic hierarchy process,which can quantitatively reflect the consistency degree of the energy storage single battery,and avoid the inconsistency and extnsive classification.It can provide theoretical support for battery operation and maintenance analysis of the energy storage power station and improve the safe operation of the energy storage power station.

Research on Electric-Hydrogen Hybrid Energy Storage System Based on Lithium Battery

CAO Ziquan, LI Yaxin, MA Lingyi, LIU Haitao, LI Jianlin

2022, 0(5): 29-34. doi:10.16628/j.cnki.2095-8188.2022.05.005

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In order to achieve the medium and long-term goals of “carbon peaking” and “carbon neutrality”,as well as promote the development of new energy technologies,solve the imbalance of electricity demand,and reduce the pressure on the power grid peak load regulation.The hybrid energy storage technology has become a key to solving the problem.The hybrid energy storage system composed of the energy-type energy storage devices and the power-type energy storage devices is a system with both energy and power advantages,which greatly improves the power performance and economy of the system,which can not only smooth the fluctuation and randomness of the renewable energy generation,but also effectvely solve the problem of the insufficient power grid peak load regulation capacity.Therefore,the combined application of two or more energy storage technologies can effectively improve the grid-connected capability of the renewable energy and solve the above problems.The modeling,advantages and the simulation current state of different energy storage systems,and solutions and recommendations to address the growing burden on power grid are put forward.

Short-Long Term Coordinated Electric-Hydrogen Hybrid Energy Storage Capacity Optimization Planning

LI Yu, ZHANG Hong, CUI Xiaobo, SUN Qianyi, JIA Hao, YUAN Bo, LI Taihua, WANG Heng, YUAN Tiejiang

2022, 0(5): 35-40. doi:10.16628/j.cnki.2095-8188.2022.05.006

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The ultra-high ratio and ultra-large scale new energy sources connected to the grid pose a huge challenge to the safe,stable and economic operation of the power system.For the surge of the system flexible regulation resources,the short-time electrochemical energy storage can not cope with the long-time power shortage of the system,which requires a larger scale and longer time regulation method.First,taking the operation cost of thermal power units as the optimization target and the maximum discharge time of electrochemical energy storage as the boundary,the short-time energy storage and long-time energy storage are divided.Then,the optimal operation model and capacity allocation method based on the operational simulation of hybrid energy storage system is put forward,which are solved by MATLAB optimization toolbox CPLEX.Finally,taking the actual data of a district in northwest China as an example,the urgent demand of the new power system for the long-time and large-scale regulation means is verified,and the configuration results of the hybrid energy storage in this region under the different boundary conditions are calculated to provide the theoretical support for its energy storage planning layout.

Day-Ahead Dispatching Interval Optimization of Power Grid Considering Impact of EVs Number

YANG Junchen

2022, 0(5): 41-46. doi:10.16628/j.cnki.2095-8188.2022.05.007

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To address the impact of different numbers of electric vehicles (EVs) and uncertainty of wind power output on power grid dispatching,the day-ahead dispatching interval optimization model with the uncertainty of wind power output and EVs is established.First,the uncertainty of wind power output is represented by the interval number.The interval optimization model of day-ahead dispatching is established by considering the different numbers and operation constraints of EVs.Then,the interval optimization model of day-ahead dispatching is converted into two sub-models for solving.Finally,the proposed model is tested and analyzed by using the 10-unit system.The accuracy and economy of the proposed model are verified through the analysis of arithmetic cases.

Power Smoothing Strategy for Wind PV Energy Storage Microgrid Considering Energy Storage Losses and Power Prediction Errors

ZHANG Maolin, XIAO Hui, ZENG Linjun, ZHAO Wenqin, WANG Jun

2022, 0(5): 47-54. doi:10.16628/j.cnki.2095-8188.2022.05.008

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In a microgrid containing wind power,photovoltaic power,residential load,battery,supercapacitor and electric vehicles,a power smoothing strategy considering the energy storage loss and power prediction error is proposed to smoothen the grid-connected power fluctuation.Firstly,the day-ahead prediction data of grid-connected power were decomposed by wavelet packet,and the power fluctuation was smoothed by battery and ultracapacitor.The optimal regulation model was established to optimize the output of battery and ultracapacitor.Then,a rolling optimization scheduling model based on the model predictive control was established for the error of power day-ahead prediction data,and the error was eliminated by adjusting the orderly charging and discharging of electric vehicles.Finally,a real microgrid simulation model was constructed.The operation results meet the expectations,which shows that the proposed method can effectively reduce the over-charge and over-discharge of energy storage,and improve the ability of the grid-connected power tracking scheduling.

Distributed Energy Storage MPC Coordinated Control Method for Distribution Network Considering Economy and Robustness

XIAO Jianfu, ZHANG Liang, HUANG Juan, HUANG Bin, XIAO Hao

2022, 0(5): 55-64. doi:10.16628/j.cnki.2095-8188.2022.05.009

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Aiming at the coordinated optimal control problem of the distributed energy storage (DESS) in distribution network,a two-stage model predictive coordinated control (MPC) method for the distributed energy storage in distribution network considering economy and robustness is proposed.In the day-ahead stage,the rain flow calculation method is used to quantitatively evaluate the life of DESS,and the randomness of the renewable energy and the load power is considered in detail to formulate,the day-ahead economic operation benchmark plan of DESS.In the intra-day stage,based on the voltage sensitivity matrix,the MPC coordinated control model of DESS based on state space is constructed,and the advanced optimization regulation and the rolling control are implemented for each DESS,which ensure the tracking of the economic optimization plan of each DESS,the voltage fluctuation caused by the short-term load power.The test case analysis on the modified IEEE 33 node show that compared with the traditional power flow section control scheme,the proposed method can reduce the SOC tracking control error and node voltage deviation by 28.4% and 39.2% respectively.

Microgrid Energy Management Considering Flexible Charging of Electric Vehicles Based on Grid Time-of-Use Price Mechanism

HE Zhaorong, GAO Yiyun, HUANG Hanting, LIU Zhao

2022, 0(5): 65-70. doi:10.16628/j.cnki.2095-8188.2022.05.010

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With the continuous popularization and promotion of new energy electric vehicles,ensuring smoother grid power fluctuations has become one of the important issues to be faced at present when the vehicles are flexibly connected to the grid.Aiming at the lowest grid operating cost and takeing wind,photovoltaic and other power generation methods as the object,the microgrid energy management system model is established,by considering the characteristics of the grid time-of-use electricity price and reasonable energy storage,and comprehensively considering the ordinary loads and electric vehicle loads.Under the normal weather and the special weather conditions such as rainy and windless,using different microgrid operation strategies,combining with the ratio of the number of precipitation days to the number of sunny days in Shanghai each year,the simulation is completed.The results show that the model not only can reduce the cost of power grid operation,but also reduce the waste of power resources.

Dynamic Coordination Control Strategy for DC Active Distribution Systems with Multi PV-Storage Microgrids

MA Muyuan, ZHAO Yanhui, LI Guoqing

2022, 0(5): 71-77. doi:10.16628/j.cnki.2095-8188.2022.05.011

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Aiming at the stable operation of the distribution network system with distributed power access,a dynamic cooperative control method for the distribution system with multi PV-storage microgrid is proposed.Firstly,a radial DC active distribution system structure with the two-level DC bues of the distribution network and microgrid is designed,and the adjacent microgrid level DC bues are connected by tie switches.Different operating modes of the system under grid-connected and islanded operation are designed.To ensure the stable operation of the system,a dynamic coordination control strategy among interface units including P/Q control,U_DC/Q control and U/f control is proposed.Finally,through MATLAB/Simulink simulation experiments,the correctness and effectiveness of the proposed control strategy are verified from four aspects of photovoltaic system (PVS) output fluctuation,load capacity change,fault and connected-grid switching.

Charge Balance Method of Series-Connected Battery Packs Based on Genetic Algorithm

QIU Shengshi, CHEN Saihan, LIU Xinwei, LYU Kai, CHEN Siwen, SUN Jinlei

2022, 0(5): 78-82. doi:10.16628/j.cnki.2095-8188.2022.05.012

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The inconsistent charge of the single battery pack in series will lead to the reduction of pack capacity and power,which endanger the use safety of the battery pack,so it is very necessary to carry out the efficient charge balance management for the battery pack.In order to solve the problem of low energy transfer efficiency during the equalization,a charge balance method based on genetic algorithm is proposed.The energy transfer equation based on the equalization topology is written.The energy optimization model is established by taking the energy consumption as the optimization goal.The genetic algorithm is utilized to solve the optimal equilibrium path and determine the equilibrium transfer power of each battery.So the available battery pack capacity is increased.Finally, the experimental results show that the difference of charge after the equalization in the battery pack is reduced from 8% to 1.7%.Compared with the traditional average charge method, the equalization time is reduced by 29.4% and the available capacity of the battery pack is increased by 8.3%.

Digital Hysteresis Control Strategy for LLC Resonant Converter Suitable for Battery Charging

JI Shengzhi, JIANG Haoran, LIU Shengyu

2022, 0(5): 83-87. doi:10.16628/j.cnki.2095-8188.2022.05.013

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LLC resonant converter has low switching loss and high working frequency,which can meet the requirements of high power density and high efficiency.In practical battery charging applications,it is often necessary to face the problem of wide changes in output voltage and current.In order to keep the output stable,the hysteresis control strategy of LLC resonant converter suitable for battery charging is proposed.It has the advantages of simple implementation method,rapid response and wide output variation.The experimental results show that the hysteresis control has a good ability to adapt to a wide range of the output.

Energy Feedback Activation System of Transformer Substation Battery Pack

MA Yan, WU Hang, ZHOU Ya, CAO Hai, HUANG Haihong

2022, 0(5): 88-92. doi:10.16628/j.cnki.2095-8188.2022.05.014

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As the backup power supply of transformer substation DC system,the regular activation is an effective means to detect the capacity of the battery pack and find out the backward battery.In view of the fact that the traditional battery activation device consumes the energy released by the battery through the resistance,which has energy waste and potential fire hazards,a set of energy feedback activation system of the transformer substation battery pack is designed.The system includes the DC/AC grid connected converter,DC/DC converter,the monitoring and battery detection device,which can realize the energy feedback of the battery pack to the power grid and the AC side high power factor.The working principle is analyzed,and finally the function of the experimental prototype is verified.

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