PC-based control: the integrated control platform for tidal turbines

With its openness, scalability and flexibility in the design of the controller the Beckhoff control architecture is perfectly suited to the requirement profile of tidal turbines. For all product ranges, from Industrial and Embedded PCs, Control Panels, and I/O components to the TwinCAT automation software, Beckhoff offers modular solutions with precisely scalable performance. Interfaces for all common fieldbuses and the large signal variety of the Beckhoff I/O modules cover all types of signals and fieldbus systems that are relevant to tidal turbines. You can configure a performance-related controller from our standard components just as though you were working with a construction kit – and the modularity of this solution means that extensions and modifications can also be made later on. The integrated PC control platform eliminates the “black boxes” of hardware-based safety or monitoring solutions and ensures that all system components interact efficiently, so you benefit from more efficient tidal turbines with improved availability, plus lower hardware and engineering costs. In addition, the smooth interaction of the Beckhoff technology with industrial communication standards such as IEC 61850, Ethernet TCP/IP, and OPC ensures that your investment remains secure.

With PC-based control, you benefit from:

• a universal control platform for operational management, pitch control, and condition monitoring
• high flexibility when it comes to controller design
• performance-related scalability
• modular expandability
• reduced hardware and engineering costs
• increased efficiency
• improved competitiveness

TwinSAFE: the modular and scalable safety solution

With TwinSAFE, Beckhoff provides tidal turbine developers with a universal, certified safety concept that integrates all safety-relevant functions into the standard control platform, removing the need for a separate safety controller. Due to their modularity and versatility, the TwinSAFE components fit seamlessly into the Beckhoff control system. The I/O components are available in EtherCAT Terminal, EtherCAT plug-in module, and EtherCAT Box module formats, with IP20 and IP67 protection degrees. The safe signals can be mixed as required with the standard signals that are needed for the actual system automation processes, making it possible to use the standard signals for safety-relevant tasks.

The safety-relevant functions for monitoring emergency stops, speed, power, or shock, as required by standards such as DNV GL guidelines for certifying tidal turbines, are programmed and configured either in EL6900 or EL6910 TwinSAFE logic terminals or in TwinSAFE I/O terminals with integrated TwinSAFE logic based on standard safety function blocks.

Highlights of TwinSAFE and FSoE:

• processing of digital and analog signals
• integration of safety-relevant functions into the existing architecture
• existing controller can “listen in” to FSoE communication; i.e., it can respond to safety-relevant signals and situations, log them, or communicate them
• implementation of safety-oriented requirements from various system configurations in a shared TwinSAFE application: customizing enables options for each system type
• EP1908: speed recording without an analog encoder, safety behavior triggered when a parameterizable threshold value is exceeded, additional reading out of analog speed values via CoE (CAN over EtherCAT)
• functionality assured even when EtherCAT cable redundancy is being used

EtherCAT: the high-speed fieldbus for tidal turbines

As a fieldbus system, EtherCAT delivers all the features that are needed for control and signal transmission in tidal turbines. The EtherCAT fieldbus enables high-performance, integrated communication with all devices over Ethernet, without the need for couplers or converters. At the same time, every connection, every transformer, and every device can be monitored and diagnosed in detail to detect any malfunction immediately and determine the cause.

On account of its high bandwidth, EtherCAT takes care of not only processing all standard signals, but also high-precision measurement technology and safety technology signals. Fieldbus masters from standard fieldbuses can be easily implemented in the field. The system can also be set up with cable redundancy. EtherCAT can even be found in subsystems that make the highest demands on speed and synchronicity – in converters, for example.

TwinCAT as an automation and runtime environment for operational management

The TwinCAT 3 automation software is integrated in Microsoft Visual Studio and allows the application software to be developed according to the programming languages under IEC 61131-3, including the object-oriented extensions. Development in C/C++ is also available, as is the integration of algorithms directly from MATLAB^® and Simulink^®. The TwinCAT modules developed in this way can be freely combined with each other and executed in the runtime environment on an Industrial PC or Embedded PC. The developed software modules are independent of the hardware and can be used on a wide variety of CPUs, and combined with a whole range of I/O components and fieldbus systems.

The open and modular TwinCAT interfaces support not only internal communication and communication with the I/Os, but also the connection of subordinate or higher-level systems. This allows subsystems, parallel systems, or monitoring systems to be directly connected by means of EtherCAT or via fieldbuses such as CANopen, PROFIBUS, and PROFINET. But the openness of the platform also makes it easy to perform integration into a more extensive farm structure using fieldbus systems, such as EtherCAT or PROFINET, or establish a connection to a SCADA system via protocols such as Modbus TCP and OPC UA and the telecontrol protocols IEC 60870 or IEC 61850. Over and above this, IoT technologies can be used to collect data from a large number of distributed systems, communicate it via MQTT, for example, or write it directly to a database via systems such as SQL in order to manage farms and implement cloud scenarios.

Integrated condition monitoring increases the efficiency and availability of tidal turbines

Operating and maintaining tidal turbines entails significant costs. To keep the systems competitive, the risks of failure must be minimized, the maintenance costs lowered, and the availability and energy efficiency of the systems increased. This is where condition monitoring for gearboxes and generators comes in. Thanks to powerful processors found in our modern PC technology and the fast communication system EtherCAT, condition monitoring can be integrated seamlessly into the controller. The vibrations of bearings or electrical machines are picked up by Beckhoff’s standard measuring terminals and transmitted to the controller via EtherCAT. Configuration, programming, and diagnosis take place in one system using TwinCAT.

Beckhoff’s controller-integrated condition monitoring is superior to classic hardware-based condition monitoring solutions due to its improved error detection and holistic system analysis. Additional operational management signals for temperature, pressure, and power, for example, can be integrated into the control platform, making it possible to prevent false alarms and improve error detection. Not only that, but controller-integrated condition monitoring also offers the advantages of lower system costs and less expenditure associated with installation and maintenance. Existing systems can be retrofitted simply and inexpensively.

Integrated condition monitoring offers:

• time-synchronized recording of all data in much less than a microsecond
• reliable data analysis
• improved diagnostics
• increased system availability
• longer service life of tidal turbines
• lower maintenance costs
• lower system costs
• improved competitiveness

Powerful and flexible expansion options: the Embedded PC series for control tasks in tidal turbines

The compact DIN rail-mounted PCs from the CX series with a directly connectable I/O level offer a space-saving controller in the control cabinet. Beckhoff’s extensive range of embedded controllers includes a device tailored to the budget, performance class, and complexity of the control task in any application. Apart from the CPU, the individual devices from the CX series differ in the available system interfaces and power supply versions, and can be plugged together and expanded in the tidal turbine as a modular control system that suits the task at hand.

The CX family includes several basic CPU modules with different processors for adapting the performance to suit the control task in question. For high-performance applications – including measurement technology, for example – the CX2033 can be used as a fanless version. The CX family of the Arm^® series is often used as a pitch controller in the hub.

EtherCAT Terminal system for efficient input and output signals

Due to the wide range of fieldbus components, I/O terminals in tidal turbines can be freely distributed as EtherCAT slaves and integrated in the system using any given topology. The comprehensive choice of I/O terminals ranges from recording simple digital and analog signals through to the precise measurement of vibrations, temperatures, or strains, thus enabling almost any number of sensors to be connected. Actuators, drives, and hydraulic systems can equally be controlled via output signals, however. Subsystems are simply integrated via subordinate fieldbus systems, which are integrated with the EtherCAT system by means of communication terminals in the field.

In this respect, the fieldbus and I/O components are not only available with protection degree IP20, for DIN rail installation, but also with IP65, for installation directly on the machine. This allows the I/Os to be positioned in the control cabinet as required or directly on the sensors and actuators, such as on the gear unit, on the generator, or in subsystems like a hydraulic unit.

Universal EtherCAT into the IP67 world

The EtherCAT technology can be used without a control cabinet with the EtherCAT Box modules in IP67. The robust design of the watertight EtherCAT Box modules, plus their resistance to shock and vibrations, enables them to be used directly on the machine – even in harsh environmental conditions. Their compact size makes the EtherCAT Box modules particularly suitable for applications involving cramped space. Their ability to be used directly on the relevant control cabinet units opens up the option of smaller designs in tidal turbines. The modules from the IP67 series have an integrated direct EtherCAT interface, so that the high performance is retained right down to each module.

TwinCAT 3 Wind Framework: the complete software package for automating tidal turbines

Developed for wind turbines, the TwinCAT 3 Wind Framework modular software package also includes all the functions and tools that are necessary for modern, efficient engineering of tidal turbines. All the basic functions are encapsulated in user-friendly function blocks in TwinCAT 3, creating a kind of construction kit for the programmer and making it easier to develop application software. Apart from the basic functions for operational management and the state machine, there are software blocks for the data connection, power and condition monitoring, and simulation. The integrated database link for big data enables the comprehensive acquisition, evaluation, and provision of data from operational management, condition monitoring, and power management in real time. All data is continuously recorded, summarized in the central controller, and analyzed in detail. This way, for example, signs of wear in individual tidal turbine components that could lead to operational failure are detected at an early stage, increasing the availability of the system. The ready-made software modules and application templates are tried and tested, deliver high standards of quality, and are fit for the future. In the same way as modifications to the hardware, individual software modules can be added or removed. This makes the engineering as simple as possible, leaving the developer to focus on the actual system functions.

Another feature that optimizes the engineering work is the ability to divide it among a team, allowing development and tests on customer-specific modules to be carried out in parallel and reducing the time to market. The consistent use of the TwinCAT modules and the uniform architecture of the subsystems create an application standard. This standardization enables programmers to quickly familiarize themselves with the application and the source code, even if it was implemented by another programmer.

The TwinCAT 3 Wind Framework package offers:

• future-proof standard application software
• maximally simplified engineering
• reliable and efficient software development
• increased software quality and optimum reusability
• considerably reduced time to market
• far-reaching monitoring and interaction
• continuous recording and evaluation of signals
• use of Industrie 4.0 properties in tidal turbines