Design And Implementation Of Automatic Test For Embedded PLC System In Wind Farm

As wind power technology is progressing rapidly and the accumulative installed capacity of wind turbines have been increased continuously, the rated power of wind turbines keeps growing up and requirement for sophisticated control has been arousing new chanllenge for main controllers. As the main controller of wind turbine, the embedded PLC system is the key technology of wind turbine, it occupies a large proportion of the overall cost, its performance and function decides the stability and reliability of the wind turbine.According to the localization project of embedded PLC system, there are many different kinds of embedded PLC system modules. At present, manual testing is used in the non-standard test system, it is time-consuming and labor-intensive, low efficiency, its precision is not high and limited the capacity. Based on the analysis of the embedded PLC system architecture and operating principle, combined with the different test requirements of different modules, automatic testing technology is adopted to develop a set of automatic test system for automated testing of embedded PLC system. It is divided into three aspects, including research programs, hardware design, software development. By scheduling and logic judgment of upper computer, the functional and performance testing of CPU module, communication modules, IO modules, power module can be simultaneously achieved, and test results can be displayed.By analyzing the network topology and architecture, the automatic test of embedded PLC system in wind farm operation simple and quick, high reliability using standardized and network design. The hardware architecture of automatic test system consists of embedded PLC system to be tested, matrix switches, interchanger and programmable power supply, programmable electronic load, digital multimeter, signal generator and other equipments.The design which break up the whole into parts and the object-oriented development ideas are adopted to the software architecture. The upper computer is developed, module test support, test module detects, mark instrument control, classification tests, communication interface supports five functions are designed, and can be tested in calibration testing, routine testing, environmental testing three kinds of modes.The module FPGA driver to process input and output data of module, matrix switch FPGA program to control relays conduction and shut down, PC matrix switch driver to realize the communication between the upper computer and matrix switch are written. The data monitoring program of module communication is designed for monitoring and recording embedded PLC system communication data. The software interfaces of programmable instruments are encapsulated. In order to reduce hardware errors on the test results of analog modules, and improve the input and output accuracy of analog modules, linear quadratic fitting method is introduced in the calibration test mode. The improved digital filtering algorithm is adopted to improve anti-jamming capability of modules in environmental test mode. The state machine specification model is built to realize fault diagnosis by the initial build, fault detection and model perfect three steps. The automatic testing platform to be built in the form of Ethernet networking, virtual instrument software architecture is adopted between the upper computer and programmable instruments.By calling for standard commands for programmable instruments, the upper computer control input and output of instrument instruction through RS232 bus. Based on the TCP/IP protocol, socket is used to config matrix switch, and control channel switching.The overall test of embedded PLC system is completed, test results exported to Excel. Combined with the different requirements of various modules, the test data of different modules are analyzed in detail.Implementation of automatic test for embedded PLC system in wind farm ensure the reliability of the whole system, break through the bottlenecks which limit capacity of embedded PLC system, localization embedded PLC system will become a real "Chinese heart" in wind farm.