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Enable Ancillary Services bY Renewable Energy Sources

Periodic Reporting for period 2 - EASY-RES (Enable Ancillary Services bY Renewable Energy Sources)

Reporting period: 2019-04-01 to 2020-04-30

EASY-RES is an EU Horizon 2020 research project that will enable Distributed Renewable Energy Sources (DRES) exhibit new functionalities similar to those of conventional synchronous generators (SG), but in a controllable, adjustable way. These functionalities will be measurable and quantifiable in order to be treated as new Ancillary Services (AS) offered by DRES owners to Distribution System Operators (DSOs) and from DSOs to Transmission System Operators (TSOs), thereby, enabling the stable and secure operation of the power grids despite the increase of DRES penetration (up to 100%) and the decommission of conventional SGs.

Overall Objectives: (i) Increase the robustness of the power system towards abrupt frequency changes by introducing virtual inertia and damping, thereby adopting characteristics similar to SGs; (ii) Contribute to the stability of the grid by providing frequency-dependent active power by the DRES individually and by the distribution grids in aggregated form; (iii) Increase the DRES penetration levels at both Low-Voltage and Medium Voltage level, while avoiding investments for grid reinforcement; (iv) Make the RES more grid-friendly by reducing the short-term electric power fluctuations at both DRES and distribution grid level, and by introducing active harmonics filtering to each DRES converter; (v) Preserve the long-term grid security even under very large DRES penetration, by reducing reserve requirements after fault recovery; (vi) Develop viable business models for all the stakeholders including the small DRES owners.
"A new power-electronic converter for interfacing the DRES with the power grid has been developed to a significant degree. It is named Unified Virtual Synchronous Generator (UVSG) and is driven by a new sophisticated control method enabling it to:
1) offer true inertial response;
2) contribute to the primary frequency regulation of the power grid, thereby in its stability;
3) exchange reactive power, thereby assist in the voltage regulation within the distribution grid. In this way, more renewables (up to 100%) can be installed in the distribution grid avoiding otherwise required investments;
4) make the fluctuations of the electrical power smoother despite the abrupt changes in solar radiation or wind speed;
5) detect when and where a fault occurs within the distribution grid and react in a smart way so that the existing protection means clear the fault effectively despite the large penetration of the DRES;
6) assist in the mitigation of the harmonic pollution of the grid.

New methods for the accurate measurement and quantification of the aforementioned functionalities have been developed. In the same context we also developed the cost-functions, i.e. the additional costs and financial benefits associated with each of these AS.

In order to enable the Transmission System Operators (TSO) ""see"" the distribution grids as virtual synchronous generators, we developed innovative methodologies for the optimum aggregation of the inertial and frequency response of the individual DRES.

An ICT architecture was defined that enables the communication between TSO, DSO and DRES. Information about available AS can be gathered from the DRES. In addition, data is collected about the status of the grid for further analysis (e.g. forecasting loads etc.) and to realise accurate measurements and the quantification of AS for later accounting. The ongoing work on this architecture includes finding appropriate technologies and ways how to efficiently store the amount of data, how to cope not only with ICT faults but also faults in the power grid, and how to implement security mechanisms and virtualization techniques for an increased robustness of the grid. Elaborated end-to-end resilience and security mechanisms ensure that only allowed entities can access sensitive information.

Furthermore, we developed new innovative methodologies for the regulation of the voltage within the distribution grids either at the medium (20kV) or low (400V) voltage level based only on the reactive power capability of the EASY-RES UVSG. With these methodologies, the DRES penetration level can be increased significantly, while the usual investments for line upgrades made by the DSOs can be avoided.

New features of the UVSG enable the fault clearing in both strong and weak power grids without requiring investments in new sophisticated protection systems despite the increase in DRES penetration."
The following advances with respect to the state of the art have been made:

• the development of metrics for the measurement and quantification of the six AS mentioned above, so that they can be introduced in future AS-markets.

• The additional investment, operational and maintenance cost associated with each of the AS has been derived analytically and in parametric form.

• the development of the UVSG that exhibits all the aforementioned functionalities in a unified approach and in a controllable and adjustable way.

• new innovative methods that allow aggregators/DSOs evaluate almost in real-time, the range of possible inertial and primary frequency response a whole distribution grid can offer to the upstream transmission system without violating technical constraints. A method for the reverse procedure has also been developed.

• new method that allows the DRES to contribute in a smart way to fault-clearing process using the legacy protection systems.
• new methods for voltage regulation within the distribution grids based only on the reactive power capability of the DRES
• The innovative ICT architecture is able to have a major impact on the future communication between DSO and TSO.

In the coming period EASY-RES will:
• Test in laboratories UVSG.
• Make the distribution grids have predictable dynamic properties and pass their models to the TSOs so that they can include them in their grid stability analyses.
• Improve and evaluate the ICT architecture.
• Suggest new business models based on the new AS for every stakeholder.

EASY-RES is expected to improve energy security by allowing very high RES penetration (up to 100%) in the grid with simultaneous decommission of large SGs driven by fossil fuels. This is expected to have a great impact on the environment and will contribute to solving the global climate and energy challenges.

The developed metrics will enable the development of
(i) viable business models between DSO/TSO;
(ii) new AS markets within the distribution grids in which all DRES owners, including the small ones, can participate either alone or in aggregated communities. EASY-RES will demonstrate that the incremental (with respect to the current situation) implementation cost for the AS provision will be less than 7-10% of the DRES current cost.

The EASY-RES results will verify that the European Commission policy in supporting larger RES penetrations in the electricity grid and transforming the prosumers into active players of the future smart grids is feasible.
DRES Functionalities in EASY-RES concept