1、 Abstract The energy storage system can effectively reduce the volatility caused by more and more renewable energy sources in the power grid,improve the utilization rate of renewable energy and the stability of system.In this paper,the optimized operation mode and capacity configuration method of pu
2、mped storage station in a renewable energy grid are studied by taking the practical energy storage facility as an example.The pumped storage station is operated under its capacity constraints,and it is divided into the energy storage condition and the power generation condition by positive or negati
3、ve of the unbalanced power in the grid.On this basis,this paper puts forward the way of the pumped storage station participating in the power grid generation plan:Pumped storage station does not participate in the actual day-ahead power generation plan only plays a reserve role,in the real-time gene
4、ration plan,the pumped storage station is preferentially called to equilibrium the deviation between day-ahead forecast value and real-time forecast value of equivalent load.The mathematical model of this method and the optimization method are also given.In addition,the capacity of pumped storage st
5、ation is planned and designed by the method of probability statistics.Finally,through the analysis of the simple system with four elements and single busbar,the feasibility of the optimized operation mode is verified,and the sensitivity of the capacity of the pumped storage station is discussed qual
6、itatively based on the operating cost of the conventional power grid.Keywords renewable energy,pumped storage station,unbalanced power,optimized operation,capacity configuration I.INTRODUCTION ITH the increasing installed capacity of renewable energy,especially the development of the uncertain renew
7、able power sources such as wind power,photoelectric(PV,solar thermal power generation),the difficulty of security and stability of power grid is greatly increased.Traditionally,with conventional thermal power units to eliminate,the response speed is limited,and a large number of conventional thermal
8、 power units are required pressure operation to provide spare,when the spare capacity is insufficient,the load will also be affected.The energy storage system can effectively stabilize the fluctuation of the energy output and reduce the randomness of flexible load,and the configuration of energy sto
9、rage system can improve the utilization rate of renewable energy and improve the stability of the system.Different types of energy storage can be used in different situations to solve different problems.The practical energy storage facilities used in power grids need three characteristics:mature tec
10、hnology,large capacity and low cost.At this stage,the electromagnetic storage(superconducting storage,super capacitor storage,etc.)is fast,but the technology is immature and cannot be applied in large scale.The technology of chemical energy storage(lead-acid battery,lithium-ion battery,etc.)can achi
11、eve high conversion efficiency,but its short life and high cost do not meet the economical requirement of practical energy storage and it has some pollution to the environment.And whether the chemical energy storage or electromagnetic energy storage,energy storage operation is DC,the need for invers
12、ion into the grid,this process will produce high harmonics,it will reduce the efficiency of energy storage system.At present,only physical energy storage(pumped storage,compressed air storage,etc.)can achieve large capacity,high-density storage,and physical storage can be used long life,small impact
13、 on the environment,in the situation of increasingly serious environmental problems,it is the most practical storage mode.While pumped storage technology is the most mature,pumped storage station has fast response speed,large capacity,low cost,and it can make the energy“time-maneuvers”with the reaso
14、nable cooperation with the wind power and photovoltaic power generation.Meanwhile,the utilization of wind power and photoelectric can be greatly Research on Optimal Operation and Capacity Configuration of Energy Storage Based on Pumped Storage Station Qiang FAN1,Dong LIU1,Ke SUN2,Lijun ZHANG3,Liang
15、SHEN2,Zhaoming ZHENG2,Yikai SUN3(1.Key Laboratory of Control of Power Transmission and Conversion,Ministry of Education(Shanghai Jiao Tong University)Minhang District,Shanghai 200240,China;2.State Grid Zhejiang Electric Power Co.,Ltd.,Hangzhou 310007,China;3.State Grid Zhejiang Economy Research Inst
16、itute,Hangzhou 310008,China)W 2018 China International Conference on Electricity Distribution Tianjin,17-19 Sep.2018CICED2018 Paper No.201805280000315 Page1/62284 improved,and it is convenient for power grid for its scheduling.Aiming at the system containing wind power,photoelectric and pumped stora
17、ge station,some scholars have studied the methods of operation and capacity configuration of the system.A joint optimal operation model of pumped storage station and wind power is established,and the state transition of pumped storage station during typical day scheduling is analyzed in 1.The paper
18、2 studies the day-ahead scheduling strategy of active distribution network,makes use of the bidirectional dispatching function of the active distribution network,can give full play to the distributed power generation capacity,and adjusts the distributed power to maximize the benefit according to the
19、 best penetration rate.The literature 3 is based on the forecast of the day-ahead load and wind power output,with the aim of maximizing the benefit of the combined operation of wind power and pumped storage,considering the limit of starting and stopping of pumped storage units and the conversion lim
20、it of power generation-pumping condition,a mixed integer programming model of 96 time periods is established and solved by commercial optimization software.The capacity optimization method of pumped storage station under the combined operation mode of wind-pumped storage station is presented in the
21、paper 4.In 5 the optimization method of wind farm energy storage capacity based on wind power prediction error analysis is presented.In the paper 6,based on the investment cost and economic benefit of energy storage system,the optimal capacity configuration method to relax peak adjustment bottleneck
22、 for large scale energy storage system with the maximum of comprehensive benefits is proposed.In the paper 7,the optimal scheduling strategy of renewable energy power grid with pumped storage station is proposed from the two aspects of the day-ahead scheduling and real-time scheduling,and the relati
23、onship between the power grid operating index and the capacity of the pumped storage station is studied.Scheduling operation and capacity configuration based on energy storage facilities from the mathematical nature is a high dimensional,non-linear,multiple constraints of continuous multi-objective
24、optimization problem,the optimization algorithm is also a hot research.Scholars at home and abroad do researches mainly from the two major directions of traditional algorithms and intelligent algorithms.The traditional algorithm includes interior point method,steepest descent method,conjugate gradie
25、nt method and dynamic programming algorithm.The intelligent algorithm includes genetic algorithm 8,particle swarm algorithm 9,ant colony algorithm 10,neural network algorithm 11 and chaos algorithm 12.Starting from the operation mode of pumped storage station,this paper divides the operation of the
26、pumped storage station into the energy storage condition and the power generation condition based on the unbalanced power P(t)of the grid and combines with the dispatching operation of the power grid to study the important role of the pumped storage station in the process of power grid optimal sched
27、uling.Then,the capacity configuration method of energy storage facilities is proposed,and finally,the optimal operation mode of pumped storage station in power scheduling is qualitatively validated by analyzing the simple system of four-element single-busbar,and the relationship between the operatin
28、g cost of conventional power supply and the capacity of pumped storage station is discussed.II.OPERATION MODE OF PUMPED STORAGE STATION The pumped storage station operates under capacity constraints,including the installed capacity P M,energy capacity E M.Assume the installed capacity of energy stor
29、age and power generation aresMP andgMP respectively,the two are equal in general,can be unified as P M.At any time t,set the power of the pumped storage station is P st(t),and the storage energy is E st(t).Defined that in the energy storage state P st(t)0.In this way,the power constraint of pumped s
30、torage station is()sgM st MP P t P(1)the energy constraint is 0()st ME t E(2)The operation state diagram of the pumped storage station can be made as shown in Figure 1.Fig.1.Operation state diagram of pumped storage station In this diagram,the upper bound E M represents energy storage capacity,and t
31、he lower bound corresponds to 0 energy.The left boundsMP and right boundgMP represent energy storage installed capacity and power generation installed capacity respectively.M(t)is the operating point of the energy storage facility,and M(t 0)represents the initial point.The left sector is the storing
32、 state,the right sector is the generating state,the longitudinal axis corresponds to the switch state of storing and generating,or the shutdown state.At any time t,the E st(t)of the energy storage facility is 00()()()tst st st sttE t E t P t dt(3)Where st0 is the efficiency coefficient,storage state
33、 and 2018 China International Conference on Electricity Distribution Tianjin,17-19 Sep.2018CICED2018 Paper No.201805280000315 Page2/62285 generation state have respective efficiency coefficients.E st(t 0)is the initial energy.The analysis can be learned that the operation trajectory of pumped storag
34、e station is monotonous,the E st(t)rises monotonically during energy storage,and the E st(t)in generation state decreases monotonously.And the operation Point M(t)is always in motion and has a time variability,unless it is on the longitudinal axis.The pumped storage station must operate within the l
35、imits of its installed capacity and energy capacity.If the operation exceeds the boundary,it is necessary to adjust the conventional power supply to compensate the capacity of the pumped storage station.When P(t)0,it is in generating state.In storing state,if()0sMP P t andint max 1()stP t t E E,no a
36、ction is required for conventional power supply,in the condition of()sMP t P orint max 1()stP t t E E,theres need to reduce conventional power to eliminate excess power.Similarly,in generating state,if 0()gMP t P andint 1 min()gtP t t E E,no action is required for conventional power supply,in the co
37、ndition of()gMP t P orint 1 min()gtP t t E E,it must increase the conventional power supply to compensate for the shortage of power generation.III.OPTIMAL OPERATION OF PUMPED STORAGE STATION For power grid containing uncertain renewable energy sources such as wind power and photoelectric,the access
38、of pumped storage station must have a huge impact on power generation plans.Traditionally,power generation planning in grid is a three-step balancing process for power,including day-ahead generation plan,real-time generation plan and automatic generation control.After the introduction of the pumped
39、storage station,it does not participate in the actual generating power in the day-ahead generation plan and only plays a spare role,but in the real-time generation plan,it is called in priority for the deviation of the real-time forecast value and day-ahead forecast value of the equivalent load,and
40、then the conventional power supply is called.This paper takes wind farm as an example,combines wind power and load power as an equivalent load,expounds the function and the optimal control of pumped storage station in the process of making power generation plan.A.Objective Function Take the minimum
41、operating cost of the thermal power units in the dispatching cycle as the objective function.The function assumes that the wind power operation cost is 0,that is,wind power has the priority in the grid.2,11minT NGi g i t i g i t i i i ttia P b P c SU y(4)Where T is the total number of periods of the
42、 dispatch cycle.NG is the number of thermal power units.P g,i,t represents the power of the i-th unit in the t-th period.a i,b i,c i are respectively cost factors of generation.SU i and y i,t are start-up cost and start-up state of the i-th unit.B.Constraints 1)Power balance constraints,wg,11NG NWg
43、i t t j tijP PL P P t(5)Where NW is the number of wind farm.P wg,j,t is the power generation plan supplied to the grid of the j-th wind farm in the t-th period.PL t and P(t)are respectively the system load and equivalent load in the t-th period.2)Spinning reserve constraints The positive spinning re
44、serve of the system is provided by the available power of the thermal power units and the pumped storage station.The negative spinning reserve is provided by the power which can be reduced of the thermal power units,the pumping power of the station and the abandoned power of the wind farm.Pumped sto
45、rage stations do not participate in the actual power generation,only play a reserve role.When the energy capacity is not limited,the reserve power is the maximum power of power generating and pumping.In fact,its operating power is limited by the energy storage capacity by the end of the previous sch
46、eduling period.The expressions are shown in(6)and(7).,1 min max max,gen,11 interval,w,1min,NG NPktg i i t g i t kikNWup t wg j tjVVP I P PtRP(6)max,1 min maxg,g,wg,pump,1 1 1 interval,w wg,1min,NG NW NPkti t i i t j t ki j kNWdn t j tjVVP P I P PtRP(7)Wheremax,giP andming,iP are the upper and lower
47、limit of power generation for thermal power units.NP is the number of pumped storage station.maxgen,kP andmaxpump,kP are respectively the maximum power of generating and pumping of the k-th unit of pumped storage station.w is the reserve rate of the wind farm power penetrated into grid.I i,t represe
48、nts the operation status of the i-th unit in the t-th period.3)Day-ahead constraints of pumped storage station The pumped storage station should satisfy the power constraint and energy constraint,as shown in(8)-(10).And it cannot run in pumping and generating state at the same time,its constraints a
49、s shown in(11).2018 China International Conference on Electricity Distribution Tianjin,17-19 Sep.2018CICED2018 Paper No.201805280000315 Page3/62286 day day maxgen,gen,gen,0k t k t kP K P(8)day day maxpump,pump,pump,0k t k t kP K P(9)day day,min,0 pump pump,gen gen,max,00dtk k k k k ktV V P P V V(10)
50、day daygen,pump,0k t k tKK(11)Where gen and pump are respectively the conversion efficiency coefficient of power-energy storage capacity of pumped storage station in generation and pumping condition.V k,max and V k,min are the maximum and minimum capacity value of the k-th pumped storage station.4)R
