Blog #3
Distribution Energy Management System for the microgrid of FOSS/University of Cyprus
Authors: S. Theocharides, M. Kynigos, K. Maxouti, L. Loizou, C. Papadimitriou, V. Efthymiou
The campus of the university of Cyprus is evolving into an energy community hub capable of operating as a living lab serving the 3 functional arms of FOSS research centre and provide.
- a state-of-the-art research environment for the technologies supporting the energy transition,
- a dynamic educational platform for students to excel and living lab capabilities linked to the remaining family of labs in EU.
- service the demanding needs of the economy and industry.
Moving in this direction, the Low Voltage Experimental Microgrid Laboratory (LVEM) forms the starting point in building the required modernisation, digitalisation and distribution grid flexibility environment capable of demonstrating a novel and promising application to mitigate different grid operating conditions. As the distribution systems evolve towards an active network of intelligent loads and generation sources, it will require more intelligent hardware and software for situational awareness and controllability. A new breed of smart devices is needed that feature flexible edge computing, field interoperability and communications as intrinsic attributes of their design. The state of digitalisation in distribution systems will be advanced with use of intelligent methods and solutions that form the backbone of data analytics and artificial intelligence. Along this context, the evolution of the planned infrastructure aims to deliver a complete smart grid tool set, which will be comprised of microgrid management and digital energy management that will be controlled and managed based on the advanced PV production forecasting solution that has been already developed.
Microgrid architecture and operational aspects
The LVEM at the UCY is the first step in building the Distribution Energy Management System (DEMS) of the university of Cyprus and it is a flexible and scalable microgrid testing, demonstration and R&D platform for smart grid and other advanced energy technologies. The infrastructure comprises of DER components (grid-connected PV systems and inverters of total capacity 30 kVA), battery energy storage systems (BESS) (capacity of 10 kWh) and controllable AC and DC loads that allow full-power testing capability up to 10 kVA (AC). In addition, the infrastructure includes smart meters, DAQs and a home energy management system (HEMS) and a residential electric vehicle (EV) emulator (equipped with smart plugs emulating home appliances) for the monitoring and automated control of electricity usage within the microgrid feeder. The infrastructure is further equipped with a state-of-the-art weather station and meteorological data-sets are continuously acquired and analysed facilitating research in the area of energy meteorology.
The overall observability and management of the infrastructure is performed by a high-level management system (incorporating OpenMUC and Node-Red functionalities) that communicates with the energy resources via Ethernet, RS-485 serial, IEEE 802.15.4 and supports various application protocols such as Modbus and IEC 61850. Ultimately, the laboratory infrastructure offers a modular and scalable interoperable platform for smart grid system and DER-oriented simulation and validation/testing activities.
Digitalisation
In developing DEMS, FOSS appreciates the clear need for efficient educational methods to promote the energy transition, while digitalization of the energy system is also an important driver. University curriculums need to be updated, professionals should be trained, and retrained and young researchers should be offered opportunities for innovation. New skills and capacities are necessary in the contemporary complex environment, such as inter-disciplinary background and complex system understanding. In this framework, the main objective of this work is to efficiently educate researchers, students, and professionals on smart grid, smart energy systems, and renewables research. The excellent facilities of the project consortium will be used to provide advanced education and training (physically and remote). An online resource centre for education and training on smart grid and smart energy systems will be created, offering publicly the material and tools, while aiming to promote replicability. Moreover, learner-centred educational methodologies will be applied, such as challenge-based learning and experience-based learning, to increase the engagement of the learners, combined with advanced technical solutions.
Forecasting
The architecture of the DEMS platform, includes the PV generation platform (SUNCASTER) that provides an advanced day-ahead (DA) and hour-ahead (HA) PV power production forecasting. SUNCASTER provides an accurate point and aggregated DA and HA forecasts with normalised root mean square error (nRMSE) and mean absolute percentage error (MAPE) below the 5% threshold.
The platform foresees the establishment of a regional DA and HA PV power production forecasting model and the development of statistical upscaling and aggregation techniques to move from precise point to area site forecasts.
SUNCASTER is a combination of expert systems and machine learning models with a specific direction to artificial neural networks, while statistical processes were developed in order to further improve the accuracy of the forecasts. Additionally, SUNCASTER has an intelligent method for post-processing, which is comprised of a weather classification technique for an additional improvement on the DA PV production forecasting.
Renewable energy sources and specifically solar energy becomes one of the most promising energy resource expected through international studies to deliver 44% of the world energy by 2050 using PV based technologies. Therefore, SUNCASTER is a necessary tool to maintain low cost solutions for providing power grid stability and quality, while facilitating the energy trading into the advance wholesale energy market.
Energy Community hub Management
The energy community hub power management is of crucial importance for serving the energy efficiency objectives of the campus and the energy community objectives in general. The microgrid architecture and the hierarchical controllers are in charge of the managing and conditioning of the power exchange between the energy community and the upper grid having as main objective the energy sufficiency of the hub at the most cost-efficient mode.
The hierarchical controllers in the microgrids
The microgrid of the LVEM is intended to operate in both modes of operation i.e interconnected and islanded (planned for the near future) if needed. Real-time control in all layers of the hierarchy optimizes the operation and the commitment of the resources within the microgrid especially when islanded mode will be implemented.
The primary level: The local real-time controllers such as immediate controls (shutdown inverters), change volt/var or p-f droop and charge/discharge batteries and other automated controls are in charge of controlling both voltage and current and secure a balanced power-sharing among resources. This is quite challenging during the islanded operation once this is made available.
The secondary level: The optimization of power sharing among resources and energy efficiency is the main objective of this controller level. The energy community Renewables and emerging technologies as batteries and thermal storage (planned for the near future) will optimally balance the demand of the campus at all times. This layer is in charge for managing the synchronization process for a seamless transition between the two modes.
The tertiary level: In cases of overproduction or underproduction, the controllers and in specific the tertiary level will be in charge of managing the export/import of the power flow respectively. The respective controller is in charge also for offering and requesting flexibility through the flexibility agents (once the electricity market of Cyprus will facilitate flexibility trading) and secure the energy community objectives.
Interoperability among controllers of the microgrid and the resources/devices are of critical importance for smooth and reliable operation as already mentioned in the digitalization section.
[1] L. Meng et al., “Flexible System Integration and Advanced Hierarchical Control Architectures in the Microgrid Research Laboratory of Aalborg University,” in IEEE Transactions on Industry Applications, vol. 52, no. 2, pp. 1736-1749, March-April 2016
