Smart Electrical Grids
Background
The electricity grid is the backbone of our modern society. Its strengths are a high level of electricity delivery security and quality. The increase of decentralised energy supply forces the network to become a ‘smart grid’. Whereas conventional centralized grids can be thought of as passive bulk energy systems with one-way energy flows, smart grid systems are active systems with bi-directional energy flows. In such active systems the stability of the grid becomes delicate and also the quality decreases as voltage distortions are increasing due to e.g. inverters used by renewable energy sources. Consequently, the need arises to keep ensuring the security and quality of energy delivery in smart grids at the present high level of conventional grids.
State of the art
The present state-of-the-art is that the development of smart grids is in its infancy. The basic hardware elements for constructing a smart grid may be available, however, very little theoretical and practical experience exists on the stability of the grids that arise after implementation of these elements. In addition, the metrological infrastructure for on-site measurements of the crucial parameters in smart grids is essentially lacking.
Smart Electrical Grid project
The metrological challenges for Smart Grids are too extensive to be tackled by a single country. Therefore, a European research project was launched by VSL (and recently approved) for a coordinated and coherent approach in meeting these challenges. The three-year Smart Grids project will start autumn, 2010. In total, 18 European national metrology institutes and 4 universities and research centers, each focusing on their specific expertise, will be working in complementary tasks realizing the scientific and metrological challenges related to the successful implementation of smart electrical grids.
Aim of the project
In the Smart Electrical Grids project, a metrological measurement infrastructure will be developed to support successful implementation of a Smart Electrical Grid in Europe. The research addresses a series of metrological challenges that will provide essential support to ensure security of electricity supply and grid stability, grid quality, and fair trade between commercial parties employing the grid. Following these objectives of the project four scientific and technical work packages have been defined:
- Measurement framework for monitoring stability of smart grids via application of reliable and accurate Phasor Measurement Units (PMUs).
In the project, set-ups will be developed for calibration of PMUs, present commercial PMUs will be evaluated with respect to actual needs and field measurements will be performed in transport and distribution grids in order to prove and increase the applicability of PMUs in monitoring grid stability. - Traceable on-site energy measurement systems for ensuring fair energy trade, including
* next generation smart meters based on non-invasive load monitoring (NILM), a technique with which the energy consumption of individual appliances can be monitored.
* on-line monitoring and calibration of energy meters based on automatic meter reading, leading to reduced calibration cost and increased confidence in the calibration status of energy meters
* accurate and traceable set-ups for on-site three-phase energy measurements in medium and high voltage grids, for system calibration of revenue metering systems in these grids. - Remote on-site measurement of power quality and efficiency.
Portable systems and measurement routines for on-site power quality measurement will be developed dedicated to a series of specific applications. Subsequently, a series of on-site case studies will be performed covering ‘pilot’ smart grids, wind turbines,
rail grids, distribution grids, and substations. - Modelling, simulation and network analysis of the system state of smart grids.
Models will be developed of low and medium voltage smart grids, with the aim to optimise observability, controllability and overall design. Research concerns a.o. the optimal number and location of sensors required for reliable measurement of the smart grid system state. The modelling will be improved and validated by measurements on actual laboratory and field smart grids. Also the traceability of wideband current transformers (CTs) and reliability of smart grid data will be addressed.
Impact - stakeholder committee
This research will realise a step change with respect to the state-of-the-art, since presently:
* The metrology infrastructure for testing and calibration of PMUs is completely unavailable;
* Smart meters are still not very smart, and NILM techniques are not yet sufficiently advanced for inclusion in the next generation of smart meters; the costs of on-site calibration of energy meters is significant; and no accurate and traceable facilities for on-site energy measurements in grids are available;
* Dedicated power quality measurement systems and strategies for on-site measurements in smart grids are unavailable, but at the same time needed in the light of emerging power quality normative standards;
* Very limited theoretical and practical knowledge is available on the actual stability of smart grids; traceability of wide band CTs is unavailable; and confidentiality of smart grid data is not warranted.
Interaction with the stakeholders of Smart Electrical Grids is crucial for the successful uptake of the research results by the Smart Grid community. Therefore, intensive contacts are kept with transport system operators (TSOs), distribution system operators (DSOs), utilities, instrument manufacturers, electricity companies, and IEC technical experts (enabling of international standards development). Already before the start of the project, more than 20 organisations are part of the project stakeholder committee that aims to assure focus of the project on actual customer needs and assure a timely and smooth take-up of the research results.
Contact information
For further information concerning the "Smart Grids" project, or if you want to join its stakeholder committee, please contact Gert Rietveld, e-mail: grietveld@vsl.nl