Smart Grids
Improving the power grid: from generation to distribution
The power grid can be seen as the mean of transport of electrical energy from generators to consumers. In the next few years, we can expect major developments in the number of generators, and the characteristics of generators. These characteristics may dramatically influence the stability of the power grid, and by that the quality of supply of electrical energy. As an example, the characteristics and the controllability of (e.g.) wind turbines is wildly different from the controllability of a coal fired power plant. Among the actions which REViSITE will undertake is to explore potential interfaces between the four target sectors (grids, buildings, manufacturing and lighting), and identify existing and lacking interoperability frameworks and needs for convergence of standards, an obvious one would be the data exchange standards.
Key issue in the further development of smart grids is the maintaining of stability of the power grid while enabling a multitude of generators units, of varying capacity and controllability.
Effectively what is required here is a mechanism to balance the total generated electrical energy and the total consumed electrical energy. Such balancing mechanism basically requires the following main functions:
- Accurate and complete measurement data, in real-time, of all generated electrical energy
- Accurate and complete measurement data, in real-time, of all consumed electrical energy
- A balancing mechanism, optimising the balance against criteria such as financial optimum, ecological optimum, or other
- Control mechanisms to allow direct control of generator output and / or energy consumption.
Obviously acquiring accurate and complete measurement data from a geographically wide spread power grid, from remote locations where generators may be located, and from a multitude of energy consumers, is a technological challenge.
This process data acquisition should have the following properties:
- Data exchange must be fast, near real-time. Balancing the power grid is a rapid process, measurements on hourly basis are not useful. Measurements on second basis are acceptable. This can be achieved by building a strong and reliable communication infrastructure. Measurement devices, and measurement processing devices, should be able to handle vast amounts of data in a very short time period.
- Data definitions must be clear and unambiguous. A measured quantity should have a clear meaning. A data item named "generator output" can still mean voltage, energy, current, or indeed "on or off". Clear definitions must be used here.
- Data exchange must be standardised. Exchanging data with a vast multitude of different generator types, in a growing number of exchange methods, is clearly not efficient.
Several initiatives are active to prepare internationally accepted standards for data definition and data exchange. The IEC, ISO and CCITT organisations focus on the development of standards for data definition, and communication protocols to allow for a standard data exchange. Standards for network monitoring and control, network protection, consumption metering, are defined or are being defined.
Many standards already exist and are accepted by energy companies and by suppliers of equipment to energy companies and their clients. However with the growing number of new energy generator types, and the changing properties of energy consumers, these standards may need changing, or evolution.
It is vitally important that all systems that will connect to a data exchange infrastructure as briefly described above, indeed function according to the defined standards. It is vitally important that all such systems are tested, and certified to follow accepted, standardised, data exchange mechanisms. Any device deviating from these standards could seriously disrupt all communications and could effectively break down the balancing mechanism for some time. Therefore, besides definition of standards, the verification of conformance to those standards is of utmost importance.