Research On Corodinated Accommodation And Step Utilization Optimization In A Combined Heat And Power Microgrid

With the shortage of energy and the inefficiency of utilization,the integrated energy system(IES)which emphasises on the coupling of multiple energy sources(electricity,heat,gas,etc.)are the current research hotspots.The combined heat and power(CHP)microgrid is one of the typical applications.The CHP microgrid is based on traditional electrical microgrid,fully takes its autonomous operational capabilities and flexibility.Apply the combined heating,cooling and power(CCHP),electric heat pump and other multi-energy coupling equipment to control the heat and electricity flow.Improve energy efficiency,promote renewable energy consumption based on multi-energy complementarity.The CHP microgrid is based on users' electrical and thermal demand,and is connected to various energy-generating equipment such as renewable energy,micro gas turbines and heating elements,and improves supplied energy quality and utilization efficiency through overall planning and multi-energy complementarity.The research focus of CHP microgrid is the coupling of electricity and heat flow.Compared with electricity and heat,electricity is transmitted easily and stored difficultly,while heat is stored easily and transmitted difficultly.The electricity transmission and distribution technology is mature,and response speed is fast,which has the advantages of energy deployment.The heat has large inertia and low storage cost,and can effectively suppress the energy flow fluctuation in the multi-energy coupling system.On the basis of the control of electric and thermal coupling nodes,the CHP microgrid exerts the advantages of electricity and heat complementation to optimize energy consumption and step utilization.This paper focuses on optimal coordination accommodation and step utilization,and studies the short-time scale tie-line power smoothing strategy and the long-time scale step utilization scheduling strategy.The results are as follows:(1)Based on demand response,optimally control heat pumps with water tanks to effectively suppress the tie-line power fluctuation.The power control target of CHP microgrid tie-line is analysed.Then the fluctuation is processed by frequency division,and the low-frequency is suppressed by heat pumps switch control,the mid and high-frequency fluctuation is suppressed by The heat pump power adjustment and the electrical storage.The control strategy optimizes the number of heat pumps' switching times,so that the heat pump group is uniformly depreciated as a whole;the power adjustment is used to reduce the electrical storage's charge and discharge conversions times to save cost.The control strategy effectively stabilizes the tie-line power fluctuation,improves the enthusiasm of users participating in such projects,and reduces the cost of electrical storage to achieve economic optimization.(2)Based on the principle of energy step utilization,an energy flow model based on step utilization with heat and power coupling is established to realize optimal IES scheduling.With consideration of “temperature counterpart and step utilization” principle,the heat flow grades of IES are distinguished in detail to achieve efficiently utilization;The heat load grade is also distinguished to realize the temperature counterparts of heat supply;By taking the advantages of heat and power coupling,the proposed scheduling model can flexibly adjust the energy supply strategy according to factors such as load fluctuation,peak and valley electricity price,and has strong adaptability.(3)Based on multi-time scales,combined step utilization scheduling strategy and the tie-line power smoothing strategy and proposes a comprehensive control strategy.The scheduling strategy adjusts the operation plan of each device in CHP microgrid through the rolling optimization method.The power smoothing strategy uses electric heat pump and electric cooling as the main control components.According to the operation plan of other devices,the power smoothing strategy suppresses tie-line power fluctuation under the premise of satisfying the multi-energy load.The comprehensive control strategy simultaneously achieves low-cost economic operation and smoothed tie-line power.Finally,the whole thesis is summarized,and prospect the future work.