Models for Integration of HPSP in Power System Needs and Posibilities for PSHP Construction in Croatia

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1 Models for Integration of HPSP in Power System Needs and Posibilities for PSHP Construction in Croatia Mladen Zeljko, Ph.D. Energetski institut Hrvoje Požar

2 Some existing PSHP

3 Content Introduction Basic idea of PSHP Technologies of PSHP Current status in the world, in neighbouring countries and in Croatia Models for PSHP integration in power system Possible role of PSHP in the future Needs and possibilities for PSHP construction in Croatia Final remarks

4 Why discussion about PSHP? Challenges arise from high penetration of RES (wind and solar) - interruptible, - hard predictable, - fast changeable, - strong need for regulating possibility, - additional needs for strenghtening of transmission network The most significant electricity storing capacity

5 Using PSHP Efficiency % Off peak hours pumping ; peak hours generating (connected with price of electricity) Loss of energy is acceptable in cases : 1. when production costs or market price of electricity during generating hours are higher than production costs or market price of electricity during pumping hours. Difference should be bigger than (1-η)*100%, 2. when there is no enough capacity in peak hours and there is no other possibility than PSHP, 3. when pump cycle is using spill energy,

6 Efficiency and costs relation pumping generating 100/75 = 1.33

7 PSHP in daily diagram

8 Design of PSHP Without natural inflow in upper reservoir - Closed cycle - Open cycle With natural inflow in upper reservoir Down reservoir : - on ground - underground Water : soft (fresh) water sea water

9 Okinawa PSHP (30 MW)

10 Underground design

11 Riverbank Wisacasset Energy Center (RWEC) 4x250 MW

12 Existing (old) technologies Mature technology already 60 years using Turbine and pump together (in one package) or separate + generator Rotation direction is changing Speed not changeable (80 % of existing PSHP)

13 New technologies Variable speed - beginning of 90th in Japan, end of 90th in Europe - bigger volume (dimension) than constant speed machines - faster start and change of mode of operation (pump turbine) - higher investment costs. Main adventages comparing with old technology : more stabile operation, frequency regulation in the case of higher penetration wind and solar. Ternary units (generator, turbine, pump on one shaft.

14 Ternary unit package - vertical design (generator above turbine and pump)

15 Vertical design generator (motor) between turbine and pump

16 Ternary Units Demonstrating Hydraulic Short-Circuit Operation

17 Pump operation mode (with regulation effect) using hydraulic short circuit concept

18 Mode Change Times for Various Advanced Pumped Storage Technologies TU = Turbine, PU = Pump, SC = Synchronous Condenser

19 Possibilities for PSHP Traditional planning methodology - construction costs + O&M costs - revenue of PSHP Economical and financial analysis Not very promissing for PSHP Need for the new approach - all kind of services what can be offered from PSHP should be considered

20 PSHP Services and Contributions

21 Modelling of PSHP operation A project team, led by Argonne National Laboratory (Argonne), was tasked by the U.S. Department of Energy (DOE) to study the role and value of advanced pumped-storage hydropower (PSH) in the United States. Study : Modelling and Anylysis of Value of Advanced Pumped Storage Hydropower in the Unated States (Report 2014). In addition to Argonne, the project team included Siemens PTI, Inc., Energy Exemplar, LLC, MWH Americas, Inc., and the National Renewable Energy Laboratory (NREL)

22 Modelling of PSHP operation The main purpose of the study was to develop detailed simulation models of advanced pumped-storage technologies in order to analyze their technical capabilities to provide various grid services and to assess the value of these services under different market structures and for different levels of renewable generation resources integrated within the power system. Another goal of the study was to perform production cost and revenue simulations and assess the role and value of various services and contributions that PSH technologies provide to the power system.

23 Power System Time Frames and Operational Issues

24 FESTIV (Flexible Energy Scheduling Tool for Integration of Variable generation) FESTIV includes three models that are each run at time intervals configured by the user: SCUC, SCED, and AGC. - (SCUC security constrained unit commitment), - (SCED security constarined economic dispatch) - AGC (automatic generation control) The model uses various combinations of security-constrained unit commitment (SCUC), security-constrained economic dispatch (SCED), and AGC to schedule the system at different operating time frames. At the finest scheduling interval, the frequency at which AGC is run (which in North America is normally 4-6 seconds), the imbalance between generation and load is calculated, as are the production costs. The costs and imbalances at this resolution give realistic metrics that can show how well the system is balanced, how well it avoids extreme imbalances and how much it costs to run that system.

25 CHEERS (Conventional Hydropower Energy and Environmental Systems ) A team of national laboratories is developing and demonstrating a suite of advanced, integrated analytical tools to assist managers and planners in increasing hydropower resource efficiencies while enhancing environmental performance. As part of this effort, Argonne National Laboratory (Argonne) is developing the Conventional Hydropower Energy and Environmental Systems (CHEERS) model to optimize day-ahead scheduling and real-time operations. CHEERS can help operators in making decisions about unit commitments and turbine-level operating points using a system-wide approach to increase hydropower efficiency and the value of power generation and ancillary services. The model determines schedules and operations that are constrained by physical limitations, characteristics of plant components, operational preferences, reliability, and environmental considerations. The optimization considers head and tailwater implications, cascade interactions, turbine efficiency curves and rough zones, switch and transformer limitations, and operator preferences.

26 Results of the study Recognizing the need for better representation of PSH plants in power system simulation models, the project team developed new dynamic models for advanced PSH technologies (AS and ternary PSH units). The models were developed as vendor-neutral and, while integrated into the PSS E model for the dynamic analyses performed during the study, the new models are also publicly available (as block diagrams and transfer functions) for integration into other software packages. The project team also improved modeling representation of PSH plants in current state-of-the-art power system simulation tools (PLEXOS, FESTIV, and CHEERS) that are capable of high-resolution simulations of power systems using sub-hourly time steps. The study demonstrated that PSH plants provide a variety of benefits to the power system.

27 Results of the study While in the past the benefits of PSHP plants were usually associated only with the energy arbitrage and contingency reserves, this study clearly shows that these are just a fraction of the total value that PSHP plants provide to the system. Many of the PSHP services and contributions are usually taken for granted, and for many of them there are no established mechanisms to provide revenues to PSHP plants for providing those services or contributions to the power system. The study shows that the value of PSHP plants increases with higher penetration of RES in the system. PSHP can help in enabling larger integration of RES technologies into the system and reducing the limit of excess variable generation, PSHP plants reduce the overall system generation costs, provide flexibility and various operating reserves necessary for system operation, reduce cycling of thermal generating units and associated startup/shutdown and ramping costs, reduce transmission congestion, increase the reliability of system operation, and provide many other benefits. In addition, with a larger share of RES in the system, PSHP plants tend to have a positive impact on system emissions, as a larger share of pumping energy is provided by RES generation.

28 Installed capacity of PSHP

29 PSHP Velebit - Croatia

30 Main parameters for PSHP Velebit Installed capacity : 276 MW (2 x 138 MW) as turbine 240 MW (2 x 120 MW) as pump Inflow : 60 (2 x 30) m3/s as turbine 40 (2 x 20) m3/s as pump Constructive head : 517 m (generating mode);559 m (pumping mode)

31 PSHP Bajina Bašta - Serbia 2 x 307/ 310 MW turbine/pump efficiency : 73 % Start of operation : 1982

32 PSHP Čapljina Bosnia and Herzegovina Installed capacity 2 x 210 MW efficiency 74 % In operation since 1979

33 PSHP Avče - Slovenia Installed capacity 185 MW (turbine)/180 MW pump) Inflow 40 m3/s (turbine) /34 m3/s (pump) Efficiency 77 % Full capacity 3 min/6 min Lover reservoir: HP Plave (Soča river) In operation since 2010.

34 Possibilities and needs for construction PSHP in Croatia Operation of PSHP Velebit in the past New sites: - PSHP Vinodol - PSHP Senj - PSHP Korita In Bosnia and Herzegovina : PSHP Vrilo

35 Price of electricity on regional power exchanges (EUR/MWh) Average Peak Off-Peak Difference BSP ,02 61,95 44,09 17,86 HUPX ,49 61,33 41,65 19,68 BSP ,18 50,12 36,23 13,88 HUPX ,34 50,36 34,32 16,04 BSP ,43 46,55 34,31 12,23 HUPX ,50 47,02 33,99 13,03

36 EES [MWh] VE [MWh] Daily load diagram and wind generation Subota VE EES Sati [h] 0

37 EES [MWh] VE [MWh] Daily load diagram and wind generation 2800 VE EES Utorak Sati [h] 0

38 EES [MWh] VE [MWh] Daily load diagram and wind generation Subota VE EES Sati [h] 0

39 [MWh] Maximum and minimum load Maksimalno i minimalno opterećenje EES-a 2833 EES VE :00h PONEDJELJAK :00h PONEDJELJAK

40 Daily generation diagram of small solar plant

41 Daily load diagram Source: web page HOPS

42 Integration of 600 MW PSHP

43 Thank you for your attention