RESOLvD Improve the Efficiency and the Hosting Capacity of Electrical Distribution Networks
By Ramon Gallart Fernandez
RESOLvD is a research project under the H2020 program (2017/20, Ref. 773715, LCE-01-2016-2017) whose main objective is using machine learning and data mining to demonstrate intelligent and efficient operations in Spanish low voltage distribution network to improve management and maximize renewable generation capacity.
Therefore, it is aimed at managing flexibility in the low voltage network in the context of high penetration of distributed renewable generation and growth of electrical mobility to:
- Maximize the use of the current infrastructure through active energy management and balancing demand and supply at the LV level, including certain operating and storage capacity.
- Reduce planning uncertainty by forecasting demand and generation and applying robust optimization methods (considering the uncertainty in the prediction) for network planning.
- Improve the quality of supply (standard EN 50160) acting on the LV network.
- Reduce losses in the system through consumption of locally generated energy.
- Increase the low voltage renewable installation capacity, facilitating the utilization of generation which is not consumed locally.
- Decrease in renewable energy not supplied.
- Reduce peak demand in Secondary Substations (SS).
- Design a safe low voltage smart grid architecture and its implementation in a real pilot.
RESOLvD aims to be a solution for the operation of low voltage network on two elements: (i) LV switches, for the interconnection of lines with the purpose of changing the configuration of the network and (ii) Power electronics with batteries, installed in Secondary substations (SS) for the management of dynamic consumption. The interconnection of low voltage lines between different transformation centres has the purpose of being a facilitator for the management of congestion and its effects on voltage.
On the other hand, energy management of the batteries installed in the transformation centres allows minimizing the energy import from the grid and maximizing the local consumption of renewable energy produced locally, as well as offering a means of updating the assets of the distribution of electric power.
Management of the network is carried out in an optimal way from daily planning of the hourly setpoints of the interconnection switches and the battery charge / discharge setpoints. The optimization is carried out using predictions of the demand and generation at the consumer (or prosumer) level. The batteries are connected to the grid through converters with advanced functions which enables improvements in the quality of supply (harmonics cancellation) and improvement of efficiency (reactive compensation, balance of phase currents, etc.). The project demonstrates a greater observability of the network with the installation of synchro-phasors in the transformation centres for a rapid detection of events, faults, or simply sudden changes in the power flows (connection/load losses or unexpected generation variations).
RESOLvD has a platform that integrates different subsystems which form a solution to the management of information data and connection with the legacy systems that constitute the company's network control centre. The connection of field elements is established through RTUs and the software services (prediction, optimization, detection, and location of failures) which are integrated as web services to the platform, through standard protocols. In the design of the entire system, cybersecurity criteria are taken into account for both in the interaction with the existing distributor management systems (SCADA, AMI, MDMS, GIS) as well as in the interaction of the new subsystems which ensures safe operational conditions.
Regarding the architecture, it has been developed according to the standard (ISO / IEC / IEEE42010: 2011) that establishes a methodology for the description of the architecture of software systems. The SGAM methodology was used to identify the different actors and their interoperability at the multiple layers, physical level (interconnection of devices and communication networks), application level (access to data, computing, and information exchange between applications), and business level (coordination of functions according to business objectives). Given the heterogeneity of the origin of the data (field elements through remote (RTU), synchro-phasors -PMUs-, new power electronics equipment -PED- and storage or smart meters through the advanced tele-meter infrastructure -AMI -) the design of a software platform for integration has been incorporated to guarantee interoperability between information sources, as well as their access under cybersecurity conditions.
The real pilot consists of two Secondary Substations (SS1: 250 kVA and SS2: 630 kVA) belonging to the same medium voltage line. The network has more than thirty clients and different points with photovoltaic renewable generation. The network is tied with an operable interconnection point between two lines. The batteries (44.7 kWh) are fully allocated to the CT2 due to spacing problems in the installation. The energy storage plant consists of two battery packs (lead-acid: 4 kWh and lithium-ion: 30.7 kWh) sized to supply power for up to 4 hours to the customers in both substations during island situation and disconnection from the main grid without generation. A Power Electronics Device (PED) with three 25 kVA front inverters manages power locally and provides power quality services.
The implementation of RESOLvD technology aims to facilitate the operation of the distribution network with a strong penetration of distributed renewable generation (not controllable), providing management capacity to the network near the generation points. It is intended to demonstrate how current infrastructures can increase the renewable generation installation capacity and improve the efficiency of the system. The objective is to facilitate the installation of renewable generators and leave energy management in the hands of the distributor. This management includes not only energy storage for local consumption but also the provision of balancing services, reactive compensation, and quality of service. This requires a strategic selection of the storage connection point and its correct sizing to avoid congestion while ensuring the energy produced is consumed locally. A novel power electronics device is responsible for managing this energy according to the schedules provided by the platform in the face of congestion episodes or voltage violations limits, while providing balancing and clearing services autonomously.
The development has considered the analysis of the business models in the operation of the distribution networks, as well as the possibilities of exploitation of the technologies developed.
This article edited by Mehmet Cintuglu