Turbine control software development
The control software development is one of the central aspects when designing a wind turbine. The quality of the controller algorithms is crucial for the safe and efficient operation of wind turbines. W2E’s controller software fulfils the current operating and safety standards given in the DNVGL guideline.
The development of efficient turbine control software is an essential part of the wind turbine design. Due to the strong influence of the control software on the loads acting on the wind turbine W2E permanently enhance their controller software to keep their wind turbine developments on cutting edge technology. Currently W2E works in parallel on the development of classical and advanced controller schemes for wind turbines. The W2E staff has more than 20 years experiences in the development of wind turbine controller software.
The classical controller schemes based on PID algorithms enhanced by advanced filter technologies are currently standard at W2E. The advantages of that technology are the easy maintenance and the low requirements to the controller hardware. All parameters used within the controller software are the result of an optimisation process done for various operating points.
To be prepared for future developments W2E cooperates with the renowned Institute of Automatic Control (read more) of the RWTH Aachen University to develop cutting edge model predictive controller software (see details). Findings of that research are stepwise introduced to the classical controller software and practically tested on W2E prototypes.
The application software is designed for different hardware platforms: M1 (Bachmann), WP4x00 (Mita-Teknik) and I/O Field Controller 750 (WAGO). The software architecture is based on standardised languages: Instruction List, Function Block Diagram, Sequential Function Chart and Structured Text (IEC 61131). Also C and C++ codes are applied.
Supported SCADA systems are WPS (Bachmann) as well as MiScout and Gateway (Mita-Teknik). Interfaces to third party SCADA systems are implemented according to IEC 61400-25 or other customer-defined protocols.
Wind farm management applications are designed for different hardware platforms, e.g. M1 (Bachmann) and WP4x00 (Mita-Teknik) with interfaces to the utility and direct marketing.
The Safety Systems has major importance regarding the safe turbine operation as well as the personal protection and as method against machine breakage. Hazard analysis and risk assessment are fundamental measures to avoid dangerous operation conditions.
Operation management and safety concept of the turbine constitute the main basis topic. W2E executes the required Hazard Analysis and Risk Assessment according to the European Machinery Directive 2006/42/EC.
Safety functions are defined according to EN ISO 13849-1 and validated according to EN ISO 13849-2. Performance Level are calculated and proven. Detection of and acting to overspeed and threshold value exceeded vibrations is implemented and proven according to the Performance Level of d. Cable twisting, short-circuit, emergency stop, transformer protection, fire detection and PLC failures are also supervised by the Safety System.
Safety Systems are designed based on safety devices from Pilz, Bachmann, SIEMENS and Mita-Teknik. Requirements of the Guideline of the Germanischer Lloyd, Edition 2010 are fulfilled excellently.
W2E also offers different measures in order to avoid fire. Simple but effective fire detection and automatic fire extinguishing systems are developed together with a specialist company. Furthermore standardised TN-S grid topology is applied in combination with residual current detection.
Experimental investigations of noise and vibration
Using its own measurement equipment W2E is active in the field of experimental structural dynamics. The following investigations can be carried out:
- Application of classical and operational modal analysis to all turbine structures (nacelle, tower, blade) for a modal parameter identification
- Analysis of tonalities and its reduction
- Sound path analysis
- Application of vibration absorbers
- Procedure design for sound reduced operation
- Optimization of turbine control for vibration reduction
The staff of W2E has large experiences in structural dynamics of large mechanical structures, such as wind turbines, vessel and offshore structures. The structures can be investigated with respect to its modal and forced vibration behaviour. As a result of these investigations the structure can be optimised with respect to its structural behaviour e.g. by vibration absorbers or turbine control optimisation.
Closely related to the vibrational behaviour the noise of wind turbine structures can be investigated. As a result of these investigations the tonalities of a wind turbine can be reduced e.g. by insulation. Due to the design and operation of wind turbines W2E has large experiences in the procedure design for sound reduced operation.
Modelling and simulation of electrical characteristics
The desired grid behaviour has a key role for the entire system design. The increasing share of installed wind turbines requires excellent electrical characteristics to keep a stable and high-available network.
The complete drivetrain, the Pitch System, the converter and wind field are modelled for DFIG as well as for full-sized converter systems. Controller algorithms are 100% identical applied like in the turbine controller and the converter controller. Grid characteristics are simulated based on PowerFactory (company DIGSILENT). Load flow and dynamic simulations of single turbines and wind parks are carried out (steady-state current, voltage, power, power factor). Gird failures are analysed (3-pole, 2-pole short-circuit, LVRT, HVRT).
The generation, conversation and distribution of electrical energy as well as electrical auxiliaries and the electronic control equipment are indispensable parts of modern multi-megawatt turbines. The electrical design is based on the DNVGL guideline as well as the European and IEC standards to realise well reliable and available functions of all electrical systems.
W2E offers full services of electrical designs. Detailed specifications for generator, transformer, pitch system, yaw system, control cabinet, converter, tower equipment and cables are outlined according to the specific customer needs (environmental conditions, local requirements, local content). W2E cooperates closely to well established international suppliers as well as qualifies new local suppliers.
Circuit diagrams are delivered for control cabinet, pitch system and project-specific equipment based on the program EPLAN.
W2E considers different kinds of interfaces between neighbouring systems and components. Different fieldbuses are configured and practised: Profibus, CANopen, Modbus, Ethernet, etc.
Calculation, specification and routing of cables result in cable list, cable routing layout and definition of cable sets including their plug-connectors.
Multibody simulation is the most powerful dynamic simulation tool for complete mechatronic systems. General purpose multibody simulation tools, such as MSC.Adams and alaska, provide the possibility to calculate any arbitrary dynamic system.
Multibody systems are a simulation method for complete dynamic systems with a practically unlimited depth of details. Typically multibody systems comprise a finite number of rigid and flexible bodies connected via ideal constraints and joints. Furthermore force, damper and actuator elements can be included into system simulation. The flexible bodies are typically modelled by a modal representation allowing the simulation of large rigid body motions covered by small displacements keeping the degrees of freedom at a minimum level.
The extension of multibody systems by user routines allows the consideration of automation and control routines. Furthermore there exist predefined interfaces to MATLAB/Simulink for designing and testing control algorithms using a realistic control path.
The W2E staff has strong experiences in multibody simulation in the fields of wind energy, aircraft engineering (more details) and general research on that topic. A close cooperation in research and education to the Chair of Technical Dynamics (see more) of the University of Rostock keeps W2E up to date on recent developments in multibody technology.
FEM and structural optimisation
Finite element analysis (FEA) as applied in engineering is a computational tool for performing strength analysis. To solve the problem, it subdivides a large problem into smaller, simpler parts that are called finite elements. FEA simulations provide a valuable resource as they remove multiple instances of creation and testing of physical prototypes for various situations.
At W2E FEA is applied with respect to the effective guidelines to design and optimise all relevant structural components of wind turbines, including casted parts, welded structures and composites.
To ensure realistic boundary conditions the interaction of the analysed component with the surrounding structure is generally considered. Using the software MSC.Marc all kinds of non-linear effects, such as contact interfaces, material effects and clearance can be taken into account. Special care is taken on the modelling of bolted connections and bearings, considering the internal bearing design, contact angle, operating clearance, roller and raceway profiles, load sharing between rolling elements, as well as temperature effects.
For fatigue calculation W2E has developed in-house software tools. To consider the complex stress condition in a realistic manner time series are applied and multi-axial stress approach is used.
Topology optimisation is a mathematical method that optimises material layout within a given design space with the aim to minimize the component masses. It is used at the concept level of a design process and has a wide range of applications in aerospace, mechanical, bio-chemical and civil engineering. At W2E the optimisation software TOSCA is used to reduce masses of casted parts and welded structures significantly.
Load calculation, measurement and verification
Wind turbines are dimensioned by its structural behavior in combination with the highly dynamic loads caused by the environmental conditions. The interface loads of the wind turbine obtained by detailed dynamic simulations are the foundation of the wind turbine design. The load calculations are based on the DNVGL guideline and the IEC 61400-1 standard to fulfill the requirements of well-respected certifiers.
The dynamic load calculations are carried out using alaska/Wind, MSC.Adams and FLEX5. Flex5 has been developed at the DTU Copenhagen and is permanently enhanced by W2E. In combination with the in-house postprocessing tool FLEXAnim W2E is able to provide a basic wind turbine design within a very short period of time. For advanced dynamic simulations W2E uses the general purpose multibody programs alaska from the TU Chemnitz and MSC.Adams from MSC.Software. MSC.Adams has been extended by NREL’s AeroDyn v14.0 for including aerodynamic loads. Both multibody programs are expanded by C++ and Fortran90 user interfaces for connection with the original controller software.
The load measurements on the wind turbine prototypes are carried out according to the IEC 61400-13 standard. The load calculations using alaska/Wind, MSC.Adams and FLEX5 has been verified using real measurement data of a 2.05 MW wind turbine prototype (more details). In addition a multibody based Hardware-in-the-Loop testrig has been built-up to verify the original controller hardware.
2D/3D CAD Design
W2E has more than 20 years experiences in mechanical design and construction of wind turbines in different drive train concepts and tower designs. W2E mechanical engineering comprises and offers tasks like:
- CAD 2D/3D design of overall wind turbines from rotor, nacelle, tower, and foundation with creation of their drawings and specifications
- Design of different tower types such as tubular, lattice, concrete hybrid, and lattice hybrid tower
- Customized designs and improvements for hot & cold climate conditions, strong wind and/or dusty regions
- Design of assembly- and transport tools
- Design of lifting and repair tools
- Design of mobile onboard crane solutions for wind turbines
- Close cooperation with highly qualified, international development partners for gearbox, bearings, blades, cabine, casted and welded construction
The large experiences of the W2E staff in design and construction of overall wind turbines leads to an cost optimised, efficient wind turbine design. Also digital mock-up tests for easy maintenance access are carried out.