Wind farm networking with EtherCAT sets new benchmarks due to its high speed: in case of an LVRT, the setpoint values can be specified for all wind turbines in the entire farm network in less than 1 ms and the control of current, voltage, and frequency can be adapted efficiently. The existing fibre-optic-based Ethernet infrastructure can be used for this purpose up to distances of 20 km without a loss of speed. Even the synchronization of the IGBTs of converters within a wind farm can be realized with this technology.
Wind farm networking with EtherCAT is not only faster compared to conventional Ethernet solutions, but also offers substantial cost benefits by eliminating the need for costly switches or hubs. With the EtherCAT power measurement terminal EL3783 integrated into the automation system, momentary current and voltage values can be measured at high frequencies with up to 10,000 samples/s. With the EtherCAT distributed clocks functionality, the measured values of all wind turbines and the measurement at the feed-in point of a farm can be synchronized to a timeframe smaller than 1 μs. TwinCAT supports the standardized IEC 61400-25 communication protocol for wind turbines, which simplifies the monitoring and control of heterogeneous wind farm system environments, including the connection to electric utilities.
Beckhoff technology highlights for wind farms
Universal control platform for wind farms
As wind farm controllers, the Beckhoff Industrial PCs offer the highest performance class. On such a CPU, the wind farm controller can be implemented in cycle times of 100 µs. This makes it possible to react to the future requirements of renewable energies and to support the power grid – as long as the wind farm provides this. MATLAB®/Simulink® models for calculating wake effects can be easily integrated. Communication with power suppliers and grid operators takes place via standardized telecontrol protocols, such as IEC 61400-25 and IEC 60870. Of course the Industrie 4.0 protocols can also be integrated. Multi-core technology makes completing these wide-ranging tasks possible.
EtherCAT networks the wind farm with reaction times < 1 ms
Networking a wind farm is usually carried out with a fiber-optic cable with cable redundancy. For networking purposes, EtherCAT utilizes the same physics but, compared to elaborate switch technologies, provides a much leaner solution both in terms of price and technology. For networking the EtherCAT components, the multi-mode (up to 1.5 km) and the single-mode (up to 20 km) technologies are available. Due to the large number of EtherCAT interface components (serial, PROFIBUS, CANopen, PROFINET RT, various TCP/IP protocols, and more), this networking can also be implemented for wind farms without a Beckhoff controller.
Beckhoff product highlights for wind farms
EtherCAT infrastructure components for networking wind farms
For networking in the wind farm, both media converters and couplers are offered for the fiber optic cabling.
Multi-mode
Single-mode
For the coupling of existing control systems, the following communication modules are used:
EtherCAT Terminals integrate network monitoring and power measurement in the control system
For the purpose of independent power measurement and network diagnostics, Beckhoff offers a very powerful and cost-effective variant:
- The EL3453 measures galvanically isolated 3-phase current (up to 5 A) and 3-phase voltage (up to 690 V). The resulting average values, such as power, frequency, cos φ, and of course current and voltage, are transferred to the CPU after every half a mains period (10 ms).
- The EL3783, which is equipped with the same physical properties as the EL3453, measures current and voltage with a frequency of 20 kHz. From this raw data, all average values can be calculated on the CPU (e.g., with the help of the TwinCAT power monitoring library TF3650). It is thereby possible to perform a grid analysis up to the 110th harmonic.
Standardized protocols simplify the communication with wind turbines
With the growth of renewable energies worldwide, it has become necessary for power generators and grid operators to acquire a way of controlling these “power stations”. For this purpose, Beckhoff has developed standardized telecontrol protocols, which are available as libraries in the TwinCAT automation system.