In Europe, we are currently witnessing a sharp increase in reserve needs for coping with the variability introduced by a steadily increasing RES share in generation.
The big challenge is to extend the possibility of providing ancillary services – frequency and voltage control, congestion management – to entities connected to the distribution network and Europe's SmartNet project is trying to solve such challenges.
The legislative package proposed by the European Commission in November 2016, nicknamed the Clean Energy Package, assigns a role to distribution system operators (DSOs) for local congestion management but not for balancing. Balancing management remains in the hands of the transmission system operators (TSOs)1.
However, such sharp decoupling risks inefficient system operation.
All these issues are addressed by the SmartNet European research project (http:// smartnet-project.eu/), under technical and administrative management by RSE2, which aims to compare different TSO-DSO interaction schemes and different real-time market architectures. The goal is to find out which would deliver the best compromise between costs and benefits for the system.
The objective is to develop an ad hoc simulation platform which models all three layers (physical network, market and ICT), analysing three national cases (Italy, Denmark and Spain). This simulation platform is then scaled to a full replica lab, where the performance of real controller devices will be tested.
SmartNet also includes three physical pilots for testing specific technological solutions:
- technical feasibility of key communication processes (monitoring of generators in distribution networks while enabling them to participate in frequency and voltage regulation):
capability of flexible demand to provide ancillary services for the system:
thermal inertia of indoor swimming pools:
distributed storage of base stations for telecommunication:
The consortium, under technical and administrative management by RSE, consists of 22 partners from nine European countries, including TSOs (Energinet.dk, TERNA), DSOs (ENDESA, SE, Edyna), manufacturers (SELTA, SIEMENS), and telecommunication companies (VODAFONE).
Within SmartNet, five TSO-DSO coordination schemes are proposed and analysed from a conceptual point of view. Processes taken into consideration during the analysis relate to the prequalification, procurement, activation and settlement of the ancillary services (AS).
The coordination schemes present different possibilities to organise the interaction between system operators. Each coordination scheme is characterized by a specific set of roles, taken up by system operators, and a detailed market design.
The SmartNet project also analyses how real-time market architectures should be adapted to enable services provision from distribution networks, by taking into account the following dimensions:
Spatial dimension: the market must allow for the joint management of transmission and distribution grids.
Time dimension: the market must be able to react to the varying system conditions more quickly, closer to real-time and with some degree of anticipation of the plausible evolution of the power system state variables.
Service dimension: the market must enable the coordinated provision of power balancing, congestion management, and voltage regulation.
The simulation platform developed by SmartNet accounts for the real-time management of transmission and distribution grid congestion and power balancing while taking into account voltage and reactive power constraints. It is designed for an ancillary services market, with a high-frequency clearing pace and a short look-ahead horizon (of one hour, for instance), and a fine time-resolution.
On this platform, midterm scenarios (time horizon 2030) are implemented for Spain, Denmark and Italy and simulations are carried out in order to investigate which TSO-DSO coordination scheme fits best.
The comparison between the different coordination schemes is carried out on the basis of a cost-benefit analysis which considers the following items:
- total ancillary services market costs
- secondary regulation (aFRR) costs due to congestion not “seen” by AS market, forecasting errors, transmission losses (neglected by AS market).
- ICT deployment costs.
- Further sensitivity factors are:
- emission savings
- unwanted measures (e.g. load shedding).
Furthermore, an analysis of cash flows is carried out in order to understand the possibility of revenue from the different economic subjects in the market.
SmartNet also features three technological pilots: one in Italy, one in Denmark and one in Spain.
The Italian power system is dynamically evolving, where the large increase of RES penetration in the last 10 years is leading to a number of challenges, including a rise of active power from MV/LV to HV and the difficulty of integrating unpredictable RES with traditional generation units.
In this context, the Italian SmartNet pilot is implemented in Ahrntal, an alpine region in Northern Italy characterised by high penetration of hydro generation, to demonstrate:• aggregation of information in real time at the TSO-DSO interconnection point voltage regulation by generators connected at HV and MV power-frequency regulation (frequency restoration) by generators connected at MV.
The Danish system is characterised by a high penetration of RES (mainly wind, but, increasingly, also PV) and other highly flexible DER (CHP, waste treatment plants
and other technologies such as EVs and heat pumps which are expected to have a significant role in the mid-term).
The aim of the pilot is to demonstrate the opportunities for making use of predictable demand to contribute to transmission and distribution (T&D) grid operations. In particular, it is aimed at demonstrating the use of price signals to control the settings on thermostats of swimming pools in rental summer houses. Such price based control is expected to be able to handle many of the issues arising in both T&D grids, as well as to balance wind power generation.
The Iberian Peninsula is still weakly connected to the rest of the European power system. Also, in recent years there has been an increased contribution of both wind power and PV to the electricity supply in Spain. Under these conditions, the use of flexible demand looks a very promising tool for Spanish grid operators.
The Spanish pilot is demonstrating the prospects for the DSO of using the flexibility of mobile phone base stations to reduce congestion in distribution grids, and to help the TSO maintain system balance by fixing an exchange schedule at the TSO-DSO connection point. With that purpose, the DSO organises a local market, where different aggregators offer their flexibility. Once cleared, the market aggregators perform direct control over the DER they manage, and the DSO checks the compliance with local market results. SEI
About the author
Gianluigi Migliavacca graduated in electronic engineering at the Polytechnic University of Milan in 1991 and joined the Automation Research Centre of ENEL in 1994, working on mathematical modelling and dynamic simulation of thermal power plants. In 2000 he joined CESI and then CESI Ricerca (now RSE), where he led research activities on deregulated electricity markets and has been head of the Transmission Network Planning research group.
He has been coordinator of the European FP7 research project REALISEGRID, then work package leader on the important project e-Highway2050. Now, he is project coordinator of the new Horizon2020 research project SmartNet (2016-2018), aimed at analysing TSO-DSO coordination for allowing a participation of resources located in distribution networks (DSM, dispersed generation) to the market for system ancillary services (most notably, balancing).