A Smart Grid describes the networking and control of electricity generators, electrical equipment in energy supply networks, energy accumulators and electrical consumers. The quintessential point here is the standardisation of communication between the individual devices. Since many standards are still being defined currently, an open and flexible control platform is of decisive importance. With compact Embedded PCs and TwinCAT automation software, Beckhoff offers the optimal solution here. PC-based controllers from Beckhoff can already be found today in many applications that will shape the Smart Grid of the future, for example in buildings, wind turbines, combined heat and power plants, hydro-electric power plants or in energy network substations.
Measurement functionality integrated in the I/O system
Bus Terminal I/O can be directly and modularly connected to the compact DIN-rail-mounted Beckhoff Embedded PCs via plug connections, which helps save electrical cabinet space. Bus Terminals are available for all digital and analog signal types that are used in the industrial world. They also enable the integration of measurement tasks, which are becoming increasingly important for a Smart Grid. For example, Beckhoff offers power measurement terminals for measuring the rms values of current, voltage, active power, reactive power and apparent power in a three-phase system. Power monitoring terminals record the raw current and voltage data at a sampling rate of 10 kHz and provide the data to the control PC for further processing. Beyond that there are, among others, also analog input terminals for the measurement of temperature, resistance, pressure or vibration. The integration of the measurement technology is made possible by a correspondingly fast and deterministic fieldbus system: EtherCAT. Among other things, EtherCAT offers highly precise time stamps and temporal synchronisation mechanisms within the system as well as possibilities to synchronise to external time references such as GPS or IEEE 1588. As a result, the time synchronisation is also usable on a Smart Grid landscape distributed over a wide area.
Open communication via TwinCAT automation software
As soon as the digital and analog signals have been collected by the Bus Terminals via EtherCAT, they are transferred to the control PC. There the data are taken over by the TwinCAT control software, so that they can be further processed and analysed. Various software libraries are available to implement this functionality. This means, for example, that harmonics that result from non-linear loads in the grid can be calculated. However, TwinCAT can not only process the data, but can also communicate with the outside world via various interfaces. TwinCAT supports the IEC 60870-5-101, 102, 103 and 104 telecontrol protocols, plus the IEC 61850, which is currently in great demand for standardisation of the Smart Grid sector. Interfaces can be realised via BACnet/IP, Modbus RTU/TCP and M-bus among others. The subject of security is a very sensitive one in the field of communication; a protocol with outstanding security characteristics is available here in OPC-UA. Because TwinCAT is extremely scalable and expandable, all present-day and future applications with Beckhoff controllers are automatically ready to be integrated as a device in an intelligent electricity network – a Smart Grid.