Abstract: This paper outlines the requirements of wind power generation equipment for control systems and introduces wind power solutions based on the B&R system. It focuses on describing a wind farm monitoring system based on APROL (DCS) and a wind turbine main control system based on X20 PCC and its distributed I/O modules, POWERLINK industrial real-time Ethernet, and WTC software package. The paper also provides a comprehensive overview of the wind turbine single-unit SCADA system, wind turbine simulation model, and wind power safety system.
Keywords: B&R wind power solutions; WTC wind turbine main control system; wind farm monitoring system; wind turbine main control software package; wind turbine simulation model
B&R's Wind Power Master Control System Based on WTC
1. Application Background – Increasing Demand for New Energy Sources and Rapidly Developing Wind Power Technology
Wind power is booming in China. With the increasing severity of energy and environmental issues, green wind power is receiving more and more attention from the country, and investment is constantly increasing. In recent years, wind power has maintained a strong growth momentum of more than 30% per year.
China's wind power control technology started relatively late, and current control systems are all proprietary systems provided by European specialized control solution providers, which are expensive and have long delivery cycles. Developing control systems with independent intellectual property rights must be prioritized. On the one hand, the lack of differentiation leads to excessive transparency in future competition, resulting in fierce price competition. On the other hand, finding a suitable platform to develop independent wind power control systems will give manufacturers a competitive edge in the future.
However, wind power control systems must meet the special needs and stringent performance requirements of the wind power industry. All of this places demands on the control system platform for wind power generation. B&R's control system provides designs that are adapted to the needs of the wind power industry in both software and hardware.
2. Wind power generation equipment requirements for control systems
2.1 High standard of adaptability to on-site environment
Today, with the global emphasis on clean energy, countries around the world are building wind farms. Wind turbines can be installed in a wide range of locations, including the Northern and Southern Hemispheres, on land, and at sea. Wherever there are suitable wind resources, wind turbines can be installed. This places high demands on the components in the wind turbines. The control system, which is the brain of the wind turbine, is no exception: wide temperature range, shock resistance, corrosion resistance, and good electromagnetic compatibility have become the most basic requirements.
B&R's X20 system, used in its wind turbine main control system, was designed with these requirements in mind from the initial product design stage. In addition to passing standard certifications such as CE, C-UL-US, and GOST-R, our products underwent HALT (High Accelerated Life) testing at the German TUV laboratory. Test results show that the X20 system's operating temperature limit can reach -70°C to 100°C, and its vibration limit can reach 55g (RMS) . Furthermore, all modules of the X20 system have undergone special treatment to address the salt and moisture resistance requirements of offshore wind turbines. Simultaneously, the X20 system's MTBF (Mean Time Between Failures) can reach 500,000 hours. These hardware specifications fully meet the high standards required on-site, and the practical applications of the X20 system in various industries have proven this.
2.2 High-level language programming skills
Because power control involves numerous factors such as wind speed variations, obtaining the optimal tip speed ratio, generator output power, phase and power factors, and generator speed, it requires complex control algorithm design. This places high demands on the controller's high-level programming capabilities. B&R PCC products offer high-level programming capabilities, and in addition to these, they also include the following key technologies:
2.2.1 Complex control algorithm design capability
Traditional machine control is mostly sequential logic control. However, with the development of sensor technology, digital technology, and communication technology, complex control will be increasingly applied to machines. Machine control itself is an application that integrates a series of complex controls such as logic, motion, sensors, high-speed counting, safety, and hydraulics. PCC designers noticed this development direction early on and designed PCC products to meet this future demand.
To meet this requirement, the PCC is designed to run on a real-time operating system (OS) based on Automation Runtime, supporting high-level language programming. For wind power generation, the algorithms for pitch control, main control logic, power control units, etc. are very complex, requiring a powerful controller to implement efficient programming. Furthermore, code security must be considered in advance to protect the investment in research and development.
2.2.2 Function Block Call
PCC supports the use of the PLCopen Motion, PLCopen Safety, and PLCopen Hydraulic libraries, making it an ideal choice for wind power systems that integrate pitch motion control, safety logic design, and hydraulic control. Pitch control considers the positioning and synchronization of multiple servos, while Safety provides various safety loop designs to protect the unit's safe and reliable operation. Hydraulic control is easily integrated into the system without the need to purchase a dedicated hydraulic control module. Furthermore, PCC supports user-defined library encapsulation design, allowing users to encapsulate their core algorithms into functional blocks for invocation. This ensures code security while also providing system calls tailored to different wind turbines, greatly simplifying software refactoring and supporting rapid development.
2.2.3 All-In-One Design Philosophy – Automation Studio™ Integrated Software Development Platform
Automation Studio™ was designed with a holistic view of machine control rather than focusing on individual components or only the drive or logic. 30 years of experience in OEM control design has given B&R a deep understanding of the meaning of “holistic”. Therefore, its software package is designed to be oriented towards all objects (logic, motion, measurement, communication, display) and processes (configuration, project planning and management, diagnostics, debugging, maintenance) of the entire machine.
For B&R Automation Studio, controller design, pitch servo, hydraulic control, safety technology, and communication are all implemented in an "All In One" toolkit, Automation Studio. For systems like wind power generation that have multiple control requirements, Automation Studio provides a complete engineering design and application platform that integrates code generation, simulation analysis, remote diagnostics, and maintenance. Is there any need that cannot be met?
Leaving aside technical factors, for users, a single software solution can fulfill all application needs. This reduces the learning curve for engineers and, as a platform, provides users with a foundation for long-term, continuous innovation in software.
2.3 Automatic generation of Matlab/Simulink wind power controller code
Wind energy utilization is a systematic project involving multiple disciplines and professions such as meteorology, fluid mechanics, solid mechanics, power electronics, mechanical engineering, and materials engineering. Many components can be modeled using corresponding mathematical models, and MATLAB is a commonly used software tool for modeling and simulation. B&R Automation Studio integrates the MATLAB/SIMULINK interface, which will greatly reduce the programming and debugging time for engineering designers and lower on-site debugging costs.
Since 2008, B&R has established a deep partnership with Mathworks, using MATLAB/SIMULINK tools to provide model building, simulation analysis, and code generation design for the power industry.
2.3.1 Modeling-based system design
Control system design is based on mathematical modeling, which is the goal and fundamental theory of all engineering applications, and Matlab provides system simulation and analysis on the modeling and design architecture.
With SIMULINK, building a model is as easy as assembling a physical system. Components in the model are as convenient as actual physical wiring connections, representing ideal conduction paths. This method allows you to describe the physical structure of a system without deriving and implementing equations for the system. The model closely resembles a schematic diagram. From the model, SIMULINK automatically constructs differential-algebraic equations describing the system's operation, which can be integrated with other equations. For example, you can define models of linear and saturable transformers, surge arresters and circuit breakers, transmission lines, excitation, hydraulic and wind turbine units, and GTO and IGBT models for power electronics units. For control and measurement units, voltage, current, and impedance measurements, RMS measurements, active and reactive power calculations, and conversions from abc to dq0 and from dq0 to abc, RPL loads for three-phase units, synchronous or asynchronous generators, and motor analysis and measurement tools can all be modeled as components and connected via SIMULINK.
SIMULINK can be used to build control system models for wind turbine generators.
2.3.2 SIMULINK 's Power Application Analysis Capabilities
Simulink includes vector models for flexible transmission systems, wind turbines, and direct torque control and field-oriented control models for electric motors. Simulink provides three solutions for power system networks, as well as an ideal switching algorithm that can improve system simulation performance through high-frequency switching. Variable-step integration algorithms are used in Simulink to perform highly accurate power system model simulations. Some of these integration algorithms can handle numerically rigid systems commonly encountered in real-world power system modeling.
SIMULINK's zero-crossing detection function can detect and solve discontinuous processes with very high machine precision. Discrete simulation uses the fixed-step trapezoidal integration method to simulate the system, which is particularly suitable for power system models with power electronic devices. This mode also facilitates real-time execution of the model. Vector simulation uses a set of fixed-frequency algebras.
2.3.3 Automatic Code Generation
Using MATLAB/Simulink, the controller code for system modeling can be generated and optimized into a truly usable program. These powerful features are also integrated into Automation Studio, making it an excellent choice for developing wind power control systems.
2.3.4 B&R's simulation model partner --- ISET (German Institute for Wind Energy )
Founded in 1988, ISET is a German non-profit research institute in collaboration with the University of Kassel. It primarily focuses on research and development projects related to strategic applications of renewable energy, with 75% of its staff currently concentrated on wind power projects, including grid connection of large-scale wind farms. ISET also possesses extensive knowledge and experience in wind turbine modeling. When B&R entered the wind power field in 2007, it established a partnership with ISET. With ISET's support, we can quickly build realistic and accurate simulation models of specific wind turbines and directly import them into Automation Studio via the MATLAB/Simulink interface. This allows for the completion of most parameter calibration and program testing during the development phase, and the automatic generation of pitch and torque control algorithms from this model.
3 Wind power solutions based on B&R systems
In the wind power sector, B&R offers a complete range of solutions, including the wind farm monitoring system (APROL), the wind turbine main control system (X20), and the single-unit SCADA system (JAVA).
3.1 APROL Wind Farm Monitoring System
3.1.1 Composition of the monitoring system
The APROL system is a DCS system launched as early as 1983. It makes full use of the development of computer, network and digital communication technologies in recent years, and combines them with the process requirements of various industrial control industries. It has been widely used in various fields of industrial control such as oil and gas, petrochemical, chemical industry, power energy, environmental protection, rail transportation, metallurgy, and building materials.
The latest version of APROL is currently version 3.6. It fully incorporates many advantages of other DCS systems, such as system stability and reliability, user interface, and rich library functions. At the same time, it overcomes many shortcomings of traditional DCS systems and features a flexible, open, and efficient development environment.
A wind farm is essentially a system with multiple adjustable and real-time active and reactive power generation units. The relationship between a wind farm and its individual wind turbines is one of whole and parts, macro and micro. Therefore, based on the control system of a single wind turbine, a suitable wind farm-level DCS system needs to be designed to monitor the operating data of each turbine within the wind farm. This system can predict future power changes at different times using historical operating data and adjust the active and reactive power output of the wind farm according to grid dispatch instructions to ensure the safe, stable, and compliant operation of the wind farm. In addition to the wind turbines, the wind farm DCS system can be compatible with or integrated into the monitoring systems of the wind farm's step-up substation and meteorological observation station, improving the integration of wind farm monitoring.
Compared to traditional wind farm central monitoring systems, the APROL wind farm DCS system will consist of the following three functional components:
(1) Real-time monitoring (SCADA)
(2) Energy Dispatch and Management (PDM)
(3) Power Prediction Management (PFM)
3.1.2 Monitoring Scope
In B&R's system, remote maintenance not only means flexible implementation in terms of hardware and software, but also includes:
(1) Monitoring of various parameters
Not only current and voltage, but in fact every parameter in a wind farm, including the inputs of various sensors, I/O modules, CPU, and even intermediate variables in the software, can be remotely monitored.
(2) Operational analysis
Through its flexible software platform, B&R can also provide a data analysis foundation for the entire operation of wind farms, including management-level tasks such as equipment maintenance and root cause analysis. This can be accomplished by the B&R APROL DCS system. B&R provides not only whole-machine control and monitoring, but also management-level services for the entire wind farm.
3.2 Main Control System of the Fan
Typical network topology diagram of MW-class wind turbine main control system
3.2.1 X20 Distributed Control System
In its wind turbine main control system, B&R primarily utilizes the X20 distributed system, characterized by its openness, high integration, flexible configuration, and outstanding performance. The X20 system is based on PC-based technology, with CPU units employing the latest Intel Celeron processors, achieving a fastest task cycle time of 200 μs. All CPU units are equipped with standard USB, RS232, and Ethernet interfaces, supporting various mainstream fieldbus technologies such as PROFIBUS-DP, Modbus/TCP, and CANopen. The main CPU, I/O stations, and safety systems all utilize Ethernet PowerLink industrial real-time Ethernet, allowing signals acquired by each I/O module to be transmitted to the main CPU in real-time for conditional judgment and processing. Furthermore, converter equipment, pitch systems, intelligent sensors, and the CMS system can all acquire data in real-time via communication with the main CPU. For upper-level software, the X20 system also provides rich and open interfaces: OPC, DLL, web, FTP, etc. All configuration and debugging were completed within AS3.0—a unified development platform.
The X20 system also includes some special modules for wind turbine control systems, such as the X2OCM0985 power measurement module for measuring active power, reactive power, and phase angle; an AI/AO module with oscilloscope functionality; an X20BH fiber optic repeater module; and a PWM output module, a dedicated module for inverter control.
X20CM0985 Power Measurement and Grid Connection Synchronization Expert Module
3.2.2 Wind Turbine Main Control Software Package ( WTC Package ) – Core Software Package
The wind turbine main control software package is a software package developed by a research and development team composed of senior algorithm engineers and software engineers from B&R. After analyzing and digesting the design of some existing wind turbine control software, it was completed over a period of two years. Currently, some domestic and foreign customers are using the software package and have received very good feedback. The following are some of the design concepts of the software package:
(1) Based on the standardized IEC61131-3 language development: Structured text
(2) The software structure consists of several small parts with clear interfaces (modular structure):
●Easy to add/modify/remove individual sections
● Easy to maintain
●Easy to test
● Reusability of some code has been tested.
● Applicable to various models (doubly fed, direct drive)
(3) No restart is required for software modification and download.
(4) Integrated complete I/O diagnostics – can be maintained at runtime.
(5) Highly parameterized – parameter modifications do not cause jumps.
By utilizing a modular structure, along with B&R's qualitative time-sharing multitasking system and integrated AS development platform, the design and development of a complete wind turbine system's main control software can be completed quickly. The advantages of this solution have been well demonstrated in several collaborative projects both domestically and internationally.
3.2.3 Single-unit SCADA system for wind turbines (based on Java technology)
The SCADA system of a single wind turbine mainly performs the following functions.
(1) Real-time data information of the entire wind turbine and its components
▪ Status Information ▪ Temperature Information ▪ Speed Information ▪ Electrical Information ▪ Environmental Information
(2) Statistical data of the wind turbine
▪ 10-minute average data ▪ Event data ▪ Analysis data
(3) Fan control
▪ Shutdown, startup, reset, maintenance, parameter setting ▪ Active power regulation ▪ Reactive power regulation
Based on the above requirements, an open standalone SCADA system based on web technology was developed. In addition to the HMI on the main control cabinet displaying and operating this interface, any computer that can connect to the main control PLC can call up this interface through IE, realizing a thin client SCADA system. It realizes remote maintenance and management functions through the latest IT technology. Its main interface is shown in the figure below.
3.2.4 Wind Turbine Simulation Model
As mentioned earlier, after obtaining a series of specific parameters of the unit provided by the customer (B&R will provide a parameter list), B&R can provide a simulation model based on MATLAB/Simulink technology based on these parameters. This model will be provided in the form of library functions that can run in AS. At the same time, the model will also automatically generate a pitch torque controller related to this model. Through such a model, the main control program can be directly simulated and debugged.
3.2.5 Wind Power Safety System
The safety chain design of wind turbines can be implemented in two ways: through safety relay circuits or integrated safety modules. Both modes have their own characteristics, but integrated safety systems are undoubtedly the future trend.
B&R safety technology is currently the most efficient safety system, with a complete product line including Safetylogic, Safety I/O, Safety Motion, and Powerlink Safety. It meets SIL 3 design requirements, with a safety logic scan cycle of 1ms, making it the fastest refreshing Safety Logic product available. B&R SafetyLogic is designed based on POWERLINK real-time communication technology. Critical logic in the system, such as strong winds, severe weather, and changes in unit status like impeller overspeed, cable twisting, power failure, braking, and operator emergency button actions, is input into the system via the yellow X20 Safety I/O. The Safetylogic controller operates as a POWERLINK Controlled Node, triggering a safety logic execution process only when the corresponding I/O action occurs (these processes are designed differently depending on the source triggering the safety). Safetylogic is independent of the standard control unit.
As shown in the main control system topology diagram, B&R's solution can employ an integrated safety system, with all safety modules installable anywhere within the system. Furthermore, the B&R Automation Studio toolkit supports the PLCopen Safety library, offering 20 open PLCopenSafety function blocks. For applications like wind power generation, which involve stringent unit safety requirements, this is not only efficient and comprehensive but also open and easy to use for building safety logic.
3.2.6 Remote Diagnosis and Maintenance
(1) Remote maintenance is a necessary design feature of the system.
Remote monitoring is undoubtedly crucial for wind turbine generators, as they are often installed in locations far from urban areas, such as coastlines, valley entrances, and desert edges, where abundant wind resources are available. A system offering comprehensive remote maintenance and monitoring capabilities significantly reduces turbine commissioning and maintenance costs, and B&R's solutions provide customers with a variety of options in this regard.
(2) Multiple remote maintenance solutions
Remote diagnostics and maintenance provides a convenient solution for maintaining wind farm equipment and systems. In the B&R system, remote solutions can be implemented flexibly with little or no additional cost.
●Remote maintenance based on VNC Server
In B&R's HMI and Controller, the VNC Server and Web Server only need to be configured. They exist as software functional blocks without adding any cost. Furthermore, the monitoring software for the VNC Server is free and available, providing not only full field monitoring level permissions but also the ability to modify and set parameters.
●Web servers provide the ability to access remotely via the Internet.
Remote host data can be monitored using the built-in Internet Explorer browser in Windows, including CPU usage and current I/O parameters. Furthermore, standalone SCADA systems based on Java can also be accessed via Internet Explorer.
●FTP Server provides remote program transfer capabilities
Modifications made via the FTP Server program can be completed on the local PC and then remotely downloaded to the controller via the Internet.
●SNMP provides the possibility of sending data via email.
Email can be used to send information such as on-site data and alarm messages to the monitoring terminal's email address.
●GSM support allows critical data to be sent to monitoring engineers' mobile phones via MMS text messages in the shortest possible time, enabling timely action to be taken on on-site issues.
3. Conclusion
Today, B&R's WTC wind power control package is running stably and reliably on equipment from multiple wind turbine manufacturers (approximately hundreds of units), while also meeting customers' needs for mass production, commissioning, code reuse, and porting.
WTC is more than just a software package; it's a platform. For wind turbine manufacturers developing their own control systems, WTC's modular design greatly facilitates adjustments to equipment control according to their specific needs, thanks to its open-source code. On this platform, manufacturers can add or remove components as needed to adapt to various application environments. WTC meets the requirements of independently developing wind power control platforms, enabling domestic wind power manufacturers to quickly master core wind turbine control technologies, laying the foundation for long-term technological development and securing a leading position in future international competition.
