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Research On Control Strategy And Capacity Optimization Configuration Method Of Energy Storage Combined With Thermal Power Unit In Secondary Frequency

Posted on:2021-04-03Degree:MasterType:Thesis
Country:ChinaCandidate:P L JiaoFull Text:PDF
GTID:2392330602974742Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
With the social and economic growth,the demand for electricity continues to increase,and with the global energy shortage and environmental problems,new energy sources represented by solar energy and wind energy have developed rapidly and are connected to the grid on a large scale.Wind energy and solar energy threaten the safe and stable operation of the power system due to their weak inertia,volatility,and uncertainty,and traditional units such as hydropower and thermal power are subject to low climb rates and slow response speeds.More High quality frequency modulation resources have urgent practical engineering significance.In recent years,battery energy storage technology has developed rapidly.Because of its features such as accurate tracking,fast response speed,and bidirectional adjustment,it is regarded as the most potential auxiliary frequency modulation method.Based on the current status of energy storage participation in frequency modulation research,this paper analyzes the necessity and feasibility of traditional energy storage auxiliary power generation units.Finally,it conducts research on control strategies and capacity optimization of energy storage auxiliary thermal power units participating in secondary frequency modulation.Firstly,based on the analysis of the frequency regulation principle of the power system,a frequency regulation model for the regional power grid including the thermal power unit governor,steam turbine,and generator.And by assigning weights to the technical indicators and economic indicators of different types of energy storage and calculating their final scores,the lithium battery is selected as the type of energy storage participating in frequency modulation.Then,based on the research on the current commonly used energy storage models,a new energy storage frequency modulation model based on battery energy storage cells is proposed,eventually a regional power network frequency modulation model with energy storage participation is given.Secondly,a secondary frequency modulation control strategy for energy storage batteries based on flexible switching control methods based on frequency modulation requirements is constructed.This strategy divides energy storage into two conditions:frequency modulation and restoration.Under the frequency operating condition,divide the state interval between the frequency demand and the state of charge(SOC)to determine the switching timing and adaptive output depth of the two control modes.Performing SOC self-recovery according to the state of energy storage makes energy storage more flexible to meet the next phase of frequency-modulation tasks.Based on this,simulation analysis is performed under continuous load disturbance conditions,and the results show that the control strategy proposed in this paper has advantages in improving the frequency modulation effect of the system,reducing the energy storage frequency modulation power and capacity allocation,and improving the utilization rate of thermal power units It can realize coordinated operation among power system,energy storage battery and conventional unit.Finally,a capacity allocation method based on variational mode decomposition(VMD)with the best economical energy storage battery participating in secondary frequency modulation is proposed.The variational modal decomposition is used to divide the frequency instruction into high and low frequency components,which realizes that the frequency instruction is allocated between the two resources at an optimal ratio in each minute period.Then,based on the daily cost-benefit model of the energy storage frequency modulation,based on the measured area control error(ACE)signals,select different reconstruction points for signal allocation,configure its power and capacity,and conduct economics.And technical analysis.The results show that the capacity allocation method adopted in this paper is reasonable and effective,which can reduce the size of the energy storage battery capacity allocation,and has good technical indicators while ensuring maximum economic benefits.
Keywords/Search Tags:Secondary frequency modulation, Energy storage, Thermal power, State of charge, Control strategy, Variational mode decomposition, Capacity allocation
PDF Full Text Request
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