1、 Abstract The operation mode of electrothermal coupling in the heating season of Three North region in China is one of the essential reasons for the phenomenon of wind curtailment.It is an effective way to increase the rate of wind power utilization by heating through the electric heating and accumu
2、lation energy to remove the abandoned wind power.In particular,the heat storage station built with the combination of distributed precept and phase change materials can give full play to the advantages of flexible matching,high heat storage efficiency and rapid response.This paper takes this as a st
3、arting point and optimizes the annual heating gains of the distributed phase-change heat storage station.Under the conditions of heat storage constraints,heating constraints,and combined heat supply constraints,a case study of a distributed phase-change heat storage station based on the urban scenar
4、io partition was conducted.The results show that the heat load characteristics of the district have a significant impact on the annual return and wind power consumption.The heat storage station will get the most benefit when the capacity of the station is near the maximum heat load and the electroth
5、ermal power is about 77%of the maximum heat load.And in order to become more effective in improving the wind power utilization and reducing the heating pressure of the combination of heat and power(CHP)units,a district with a phase-change heat storage station should have a higher heat load and small
6、er peak-to-valley difference.Index Terms Phase-change heat storage station,Distributed heat storage station,Urban Scenario Partition,Wind curtailment,Economic Analysis Manuscript received July 14,2018.Shengyuan Zhong is with the Tianjin University,Tianjin,Tianjin 300072 China(e-mail:).Jun Zhao,Corre
7、sponding author,is with Tianjin University,Tianjin,Tianjin 300072 China.(phone:+86 22 27407320;fax:+86 22 27407320;e-mail addresses:).I.INTRODUCTION ITH the steady advancement of the clean energy structure in China,renewable energy generation accounts for an increasing proportion.As of the end of 20
8、17,wind energy capacity in the world totaled 539 GW,with China surpassing 164 GW 1,2.Definitely,the National Energy Board analyzed a future in which wind generation serves 6%of total China electricity consumption in the year 2020.However,the problem of wind curtailment is always the key to impede th
9、e improvement of the utilization rate of renewable energy.Gansu,Xinjiang,and Inner Mongolia in the Three North(for northwest China,north China,and northeast China)region still maintain high wind curtailment rates of 33%,29%,and 15%3.So the wind power development plan of 13th Five-Year claims the abi
10、lity that cross-province consumption of electricity in the Three North region up to 40GW by the year 2020.Nevertheless,even if transmission appears as an economic method to boost wind utilization,there are often barriers to the deployment of large-scale transmission lines 4.Energy storage is widely
11、discussed as an alternative strategy for wind energy utilization where transmission expansion may be difficult or impossible 5,6.The electrothermal coupling mode of operation has caused the systems lack of peak-shaving capacity to be the leading cause of wind curtailment in Chinas Three North Region
12、.In order to solve the abandoned wind power issue during the heating period,the heat storage device could be used to decouple the electrothermal coupling of the combination of heat and power(CHP)unit and the electric boiler be used to improve the accommodation ability of wind Hongmei Yin is with the
13、 Tianjin University,Tianjin,Tianjin 300072 China(e-mail:).Zhiyong Gan is with the State Grid Tianjin Electric Power Science&Research Institute,Tianjin,Tianjin 300010 China(e-mail:).Economic Analysis of Distributed Phase Change Heat Storage Station Based on Urban Scenario Partition Shengyuan Zhonga,b
14、,Jun Zhaoa,b,Hongmei Yina,c,Zhiyong Gand,aKey Laboratory of Efficient Utilization of Low and Medium Grade Energy(Tianjin University),Ministry of Education of China,Tianjin,300072,China bSchool of Mechanical Engineering,Tianjin University,Tianjin,300072,China cSchool of Environment Science and Engine
15、ering,Tianjin University,Tianjin,300072,China dState Grid Tianjin Electric Power Science&Research Institute,Tianjin,300010,China w 2018 China International Conference on Electricity Distribution Tianjin,17-19 Sep.2018CICED2018 Paper No.201805280000281 Page1/52269 power through increasing the electri
16、c load on the demand side.The authors of the literature 7 analyzed the wind power heating based on demand-side management technology has excellent energy efficiency.The authors of the literature 8 studied the CHP units and thermal energy storage(TES)is beneficial for reducing wind power curtailment
17、in northern China.Currently,the more common heating mode is central heating.However,with the expansion of the size of the heat supply network,the disadvantages of poor flexibility and large adjustment delay of centralized heating gradually appear.While the user-based distributed heat storage has the
18、 advantages of flexibility,rapid response,and high efficiency.At the same time,the traditional sensible heat storage device cannot meet the needs of various heat storage facilities due to the low heat storage density.The characteristics of phase-change heat storage,such as high heat storage density
19、and constant temperature,are more in line with the needs of future construction.Based on the above research,this paper analyzes the economic advantages of distributed phase-change heat storage stations which combine phase-change heat storage with distributed heat storage in different functional area
20、s from the division of urban functional regions.Compared with the centralized heating methods studied by previous generations,the phase-change heat storage station can absorb a large amount of wind power and relieve the pressure of CHP units.The obtained results provide a specific reference for the
21、demand of wind power consumption in Three North Region.II.URBAN SCENARIOS LOAD CHARACTERISTICS This article selects a typical city for analysis,which is located in the Three North Region.With the recent relocation of industrial facilities,the current commercial,residential,educational and public ser
22、vice facilities in the city mainly include residential quarters,industrial and commercial enterprises,schools and hospitals.Due to the different functions of those facilities,the heat load fluctuation rules and peak-valley differences are entirely different in each building.Therefore,when setting up
23、 a distributed heat storage station,the load characteristics of each scenario should be comprehensively considered.The simulation was performed using DeST software.Concerning the actual citys scenario partition,the heat load characteristics of residential district,commercial district,and educational
24、 district including hotels,residential quarters,hospitals,schools and office buildings are simulated separately.The necessary parameters of each building and the partition composition are shown in Table 1.TABLE I PARAMETERS OF EACH BUILDING AND PARTITION COMPOSITION According to the division of func
25、tional scenarios,the heat load characteristics of the three regions during the annual heating period(November 1 to March 31 of the following year)are shown in Fig.1.0500010000150002000025000Heat Load/(kW)Time/(Month)Commercial Residential EducationalNov.Dec.Jan.Feb.Mar.Apr.Fig.1.Heat load characteri
26、stics of the three regions during the annual heating period It can be seen from Figure 1 that the heat fluctuations of the three regions are similar throughout the heating period,especially the lower value.However,the commercial district and residential district have more high load times.If the heat
27、 storage capacity and electrothermal units are determined according to the maximum value,it will be wasteful because of the wide difference between the maximum load and the average load in the three districts.Therefore,this paper will analyze the economics of distributed phase-change heat storage st
28、ations based on urban scenario partitions and provide a feasible reference for setting capacity and electrothermal power of the stations.Hospitals Hotels Office Buildings Residential Quarters Schools Total Area(Unit:m2)4739 12292 7200 33540 3548.16 Building Height(Unit:m)24 29.7 30 25.2 16.4 Buildin
29、g Layers 8 9 10 9 4 Residential District Partition 2 0 2 5 0 Commercial District Partition 1 2 10 1 0 Educational District Partition 3 0 2 2 8 2018 China International Conference on Electricity Distribution Tianjin,17-19 Sep.2018CICED2018 Paper No.201805280000281 Page2/52270 III.PHASE-CHANGE HEAT ST
30、ORAGE STATIONS A.Heating mode Due to the wind powers random and intermittent output,the phase-change heat storage station can only use commercial power when there is no wind power available and no residual heat.This approach will increase the cost significantly.Therefore,the phase-change heat storag
31、e station and the CHP units jointly provide heat,and it is a more economical option for the CHP units to provide peak heating service,as shown in Fig.2.Wind power plantHeat storage stationUsersCHP Units Electric energyHeatHeat Fig.2.System structure of heat storage station B.Objective function The e
32、conomic analysis of the heat storage station aims at the annual revenue of the station.The objective function is shown in Equation 1.1 1 2 3 4 5F A B B B B B(1)F is annual revenue,1A is heating revenue,1B is the cost of buying heat,2B is annual conversion cost of equipment,3B is operation and mainte
33、nance costs,4B is the cost of wind power,5B is annual conversion cost of land.The expression of each item of the objective functions is as follows:11ThhtA C P(2)hC is the unit-price of heat(station),hP is the power of heating(station).11ThhtB C P(3)hC is the unit-price of heat(CHP),hP is the power o
34、f heating(CHP).21 max 2 max 3 B s e eSC C a P a P aSa(4)BC is the initial investment in equipment,S is the capacity of heat storage,aS is the capacity of the heat storage module,sC is the unit-price of heat storage module,max eP is the max power of electrothermal.2(1)(1)(1)1(1)1BBB C C(5)BC is the r
35、esidual value,is the annual interest rate,is the useful life of equipment or land.3 BfB C R(6)fR is the operation and maintenance cost ratio.41TeetB C P(7)eC is the wind power price,eP is the power of electrothermal.5(1)(1)1aSBNS(8)N is the floor space of the heat storage module.C.Constraints Since
36、the research in this paper is aimed at distributed heat storage stations in urban areas,the scale is much smaller than that of municipal heating networks and power grids.Therefore,there is no restriction on the maximum output of thermal power plants,the amount of wind power rejected,and the line flo
37、w.1)Capacity constraints t0 SS(9)2)Heating constraints max0eePP(10)hmax0hPP(11)3)Joint heating constraints h h loadP P P(12)4)Capacity status constraints ttstart endSS(13)5)Electrothermal conversion constraint e ePP(14)is the electrothermal conversion efficiency.6)Production and storage constraints
38、eP t S(15)IV.CASE STUDY A.Parameters According to the actual situation,in the example,the heat storage stations heating price is 0.24 yuan/kWh,and the used 2018 China International Conference on Electricity Distribution Tianjin,17-19 Sep.2018CICED2018 Paper No.201805280000281 Page3/52271 wind power
39、price which only contains the state grid line usage fee is 0.11 yuan/kWh.The ratio of operation and maintenance costs for the thermal storage system is 0.3%,the equipment residual value is 5%of the initial investment,the electrothermal conversion efficiency is 97%,and the equipment retirement period
40、 is 20 years.The land whose type is public service facilities use period is 50 years.B.Simulation Results According to the model and constraints established,the annual return of the heat storage stations is calculated as shown in Figure 35.Fig.3.Annual income of commercial district Fig.4.Annual inco
41、me of residential district Fig.5.Annual income of educational district With the capacity of the station being fixed,the total system revenue is generally increasing with the increase of electrothermal power.The annual revenue grows rapidly in the initial period,and the growth rate gradually becomes
42、flat as the capacity gradually approaches the maximum load.When the electrothermal power is determined,the annual income will increase rapidly as the capacity of the station increases.Due to the constraint between the capacity of electrothermal power,the annual income will finally enter a gentle pha
43、se.According to the final calculation results,the capacity and electrothermal power of the heat storage station that maximizes the annual revenue of the three regions are shown in Table 2.TABLE THE LARGEST ANNUAL INCOME POINT OF THE THREE REGIONS Commercial District Residential District Educational
44、District Maximum annual income(Million yuan)2.27 2.36 1.42 Capacity(kWh)24000 19200 12400 Ratio of capacity and maximum load 96.1%97.7%90.7%Electrothermal power(kW)19000 15000 10500 Ratio of electrothermal power and maximum load 76.1%78.9%76.8%C.Analysis of Wind Power Consumption of Heat Storage Sta
45、tion According to the calculated data,when the annual income of each region reaches the maximum value,the wind power consumption of the heat storage station in the full heating period and the heat purchase from the municipal heat network under the condition are calculated.The calculation result is s
46、hown in Figure 6.Fig.6.Wind power and heat consumption As can be seen from Figure 6,the commercial district and the 2018 China International Conference on Electricity Distribution Tianjin,17-19 Sep.2018CICED2018 Paper No.201805280000281 Page4/52272 residential district are significantly higher under
47、 the same amount of wind power consumption.Combined with Figure 1,it can be found that the business district has a larger heat load peak-to-valley difference than the residential district,so the heat purchase for the peaking is significantly higher than the other two areas.While the consumption of w
48、ind power in residential district is significantly higher than the educational district under the similar municipal heat purchase.Combined with the heat load characteristics of the two regions,it is analyzed that the heat load value of the residential district is generally higher than that of the ed
49、ucational zone,but the fluctuation law of the two is similar.Therefore,residential areas need to consume more wind power to meet greater heat load requirements,while both regions need only a small portion of the municipal heat to meet peaking needs.V.CONCLUSION Building with different heat load char
50、acteristics can obtain relatively flat regional heat load characteristics by combination.It is obvious that phase-change heat storage stations with different capacity and electrothermal power for different functional areas can better exert the advantages of phase-change heat storage stations.Through
