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Maria Carmen Falvo, PhD Assistant Professor
Energy Storage in Power Systems
2 of 20
Agenda: some questions and replies on ESS in power systems
• Why ESS in power systems?
• Where ESS in power systems?
• Which services and benefits for ESS in power systems?
• Which technologies for ESS in power systems?
• What about standards and regulation for ESS in power systems?
• Which real projects for ESS in power systems?
• What conclusions on ESS in power systems?
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Why ESS in power systems?
• The integration of Energy Storage Systems (ESS) in the electrical
power systems, was born in last years, mainly as a way to better
integrate the renewable-sources (RES) based power plants in the
transmission and distribution grids, whose huge spread has been
linked to the big attention given to the environmental problems.
• A «not-planned» spread of RES-based power plants, is acknowledged
as the cause for many new phenomena in grids operation, both on
the LV/MV system and on the HV system.
• Most of RES-based power plants are connected to the MV and LV grids,
creating the so-said Dispersed Generation (DG).
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Why ESS in power systems? • Some phenomena occurring in power systems with a huge presence of RES-
based generation are: – reduction of the inertia of the power system, with consequences on frequency
regulation;
– possible over generation, with consequences such as the necessity of rejection of part of RES production;
– morning and evening load ramps with a steeper gradient, with consequence on the steeper up/down power ramps to conventional plants;
– inverse power flow on the HV/MV and MV/LV stations, with consequence on voltage and frequency regulation;
– congestions on the HV grids with strong concentration of RES plant as wind farms;
– reduction of the short-circuit power of the grid in low load periods with the consequence of a large spread of voltage drops;
– market price distortions, due to the crisis of conventional plants linked to priority of RES dispatching at zero marginal price and due to higher power reserve margin.
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Why ESS in power systems? • All the listed phenomena can be solved with upgrading actions on the
electrical infrastructure that usually requires high capital investments and long periods for implementation, often not so compatible with the typical time of diffusion of RES plants.
• A good alternative, in terms of costs and of time of implementation, has been considered the employment of ESS in power systems.
• In the last year, it has been evaluated as a fast measure without further modifications on the operation of the networks and upgrading actions on electrical equipment.
• ESS are an alternative to other solutions such as better weather forecasting, T&D reinforcements, “flexibilization” of conventional plants, application of Smart Grids technologies for demand and RES plant, providing ancillary services.
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Where ESS in power systems? • The application of ESS can be useful
at two levels:
– in production and consumption segments, by the owners of generation and end-user plants;
– in the HV, MV and LV grids by Transmission System Operators (TSOs) and Distributions System Operators (DSOs).
• In function of the point of installation, ESS can provide different solutions for different problems.
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Where ESS in power systems?
Conventional Power Plant
RES Power Plant
MV loads
HV loads
20 kV
Frequency regulation Generation levelling Frequency regulation
Load levelling
Frequency and voltage regulation Load levelling Power Quality
Frequency and voltage regulation Load levelling Power Quality
Generation levelling Congestion relief
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Which services and benefits for ESS in power systems?
• As a reference, a list of the main services/benefits listed in the DOE/EPRI Electricity Storage Handbook, are here reported: – Bulk Energy Services: energy time-shift and energy supply capacity;
– Ancillary Services: regulation and spinning, non-spinning, and supplemental reserves; voltage support; black start; other related uses (e.g. power quality);
– Transmission and Distribution Infrastructure Services: upgrade deferral and congestion relief;
– Customer Energy Management Services: power quality; power reliability; retail energy time-shift; demand management with RES.
http://www.sandia.gov/ess/publication/doeepri-electricity-storage-handbook/
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Which technologies for ESS in power systems? • Different technologies are useful for ESS in power systems:
1. Electrochemical ESS, batteries: Lead, Lithium-ion, Nickel-Metal Hydride (Ni-MH), Sodium-Sulfur (NaS), Nickel-Sodium-Chloride – (Ni-Na-Cl2), Flow (redox);
2. Mechanical ESS: pumping, compressed air, flywheel;
3. Electrical ESS: Super-conductive Magnetic Energy Storage (SMES) and super-caps;
4. Chemical ESS : hydrogen, synthesis gas (syn-gas);
5. Thermal ESS : molten salts and heat.
• The first two categories are the most advanced and ready for, or just present in, the market of power systems application.
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Which technologies for ESS in power systems? • Different level of maturity of ESS technologies (source: DOE/EPRI 2013
Electricity Storage Handbook)
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Which technologies for ESS in power systems? • Different positioning of ESS technologies (source: DOE /EPRI 2015 Electricity
Storage Handbook)
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Which technologies for ESS in power systems? • Different application of ESS technologies among batteries and super-caps
(source: European Association for Storage of Energy (EASE) Roadmap 2030).
http://www.eera-set.eu/wp-content/uploads/148885-EASE-recommendations-Roadmap-04.pdf
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Which technologies for ESS in power systems? • Battery-ESS are the most promising technologies today for power systems
application.
Common future objectives: • Improving energy and
power density; • Improving life time and
efficiency; • reducing the costs.
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What about standards and regulation for ESS in power systems?
• IEC TC 120 on Electrical Energy Storage (EES) Systems, was born in 2013 with the aim of preparing all the documents dealing with Electrical Energy Storage (EES).
• IEC TC 120 is focused on system aspects on EES Systems rather than energy storage devices, investigating the need for new standards. For the purpose of IEC TC 120, grids include:
– transmission grids and distribution grids; – commercial, industrial grids and residential grids ; – islanded grids. – TC120 can include smart grids. Storage in railway systems is considered if it
contributes as an EES System to the grid.
http://www.iec.ch/dyn/www/f?p=103:7:0::::FSP_ORG_ID:9463
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Which real projects for ESS in power systems? • DOE Energy Storage Database: http://www.energystorageexchange.org/
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Which real projects for ESS in power systems? • Projects in Italy by Italian TSO (TERNA):
– 2 power-intensive pilot projects, approved in 2013 and included in TERNA Grid Defence Plan 2012, implemented in Sicily and Sardinia, using Li-Ion and ZEBRA batteries (in Phase 1), redox and super-caps will be tested in Phase 2. Total power: 16+24=40 MW in HV grid.
– 1 energy-intensive pilot project, approved in 2012 and included in the TERNA Grid Development Plant 2011, implemented in Puglia, using Na-S batteries. Total power: ~12+12+11=35 MW in HV grid.
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Which real projects for ESS in power systems? • Projects in Italy by Italian DSO (Enel):
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Which real projects for ESS in power systems? • Many fields of ESS application in end-users
electrical plants: – Industrial or commercial customers
(passive/active) for implementing smart grids (MV) or micro-grids (LV);
– Residential customers (passive/active) for becoming prosumers;
– Transport: integration in supplying systems of electrical vehicle from electrical cars to the high speed train for optimizing the energy management in the internal grid and towards the main grid (recovering of the breaking energy, V2G functions, etc..).
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What conclusions on ESS in power systems? • ESS in power systems are becoming a real solution for solving
different problems in short times employing only one technology.
• Among the different technologies, Battery-ESS have the biggest potentialities of application in power systems, thanks to their features.
• In the next future their spread on a large scale could be possible, if the cost will be reduced and the performance improved.
• A incentive mechanism could speed up the process of integration of these technologies in power systems.
Energy Storage and Power Systems M.C.Falvo
