Hydraulic turbine model test bed plays an important role in the development of hydropower technology. It is an important equipment to improve the quality of hydropower products and optimize the performance of units. For the production of any runner, the model runner must be developed first, and the model can be tested by simulating the actual head meter of the hydropower station on the high head hydraulic machinery test bench. If all the data meet the requirements of the user, the runner can be formally produced. Therefore, some well-known hydropower equipment manufacturers abroad have several high head test benches that meet the needs of various functions, such as five advanced high-precision model test benches of France’s nyrpic company; Hitachi and Toshiba each have five model test stands with water head over 50m. According to the needs of production, a large electric machine research institute has designed a high water head test bench with full functions and high accuracy, which can conduct model tests on tubular, mixed flow, axial flow and reversible hydraulic machinery respectively. The water head can reach 150m. The test bench can adapt to the model test of vertical and horizontal units. The test bench is designed with two stations a and B. when station a works, station B is installed, which can shorten the test cycle. A. B two stations share one set of electrical control system and test system. The electrical control system takes PROFIBUS as the core, NAIS fp10sh PLC as the main controller, and IPC (industrial control computer) realizes centralized control. The system adopts the field bus technology to realize the advanced full digital control mode, which ensures the reliability, safety and easy maintenance of the system. It is the hydraulic machinery test control system with a high degree of automation in China. Composition of control system
The high water head test bench is composed of two pump motors with an installed power of 550KW and a rotation speed range of 250-1100r / min to accelerate the water flow in the pipeline to the water head meter required by the user and keep the water head running smoothly. The parameters of the runner are monitored by the dynamometer. The motor power of the dynamometer is 500kW, and the rotation speed is between 300 and 2300r / min. there is one dynamometer at station a and station B. The principle of high head hydraulic machinery test bench is shown in Fig. 1. The system requires that the motor control accuracy is less than 0.5%, and the mean time between failures (MTTF) is greater than 5000 hours. After a lot of research, DCS500 DC speed control system is selected. The DCS500 can receive control commands in two ways, one is to receive 4-20mA signals to meet the speed requirements; The other is to add a PROFIBUS DP module to meet the speed requirement by receiving in digital mode. The first method is simple and cheap, but it will be interfered in the current transmission, affecting the control accuracy; Although the second mode is expensive, it can ensure the accuracy of data in the transmission process and control accuracy. Therefore, the system uses four DCS500 to control two dynamometers and two water pump motors respectively. As PROFIBUS DP slave station, the four devices communicate with the master station PLC in master-slave mode. The PLC controls the start / stop of dynamometer and pump motor, transmits the motor running speed to DCS500 through PROFIBUS DP, and obtains the motor running status and parameters from DCS500, and transmits them to the upper IPC through PROFIBUS FMS to realize real-time monitoring.
The PLC selects the afp37911 module produced by NAIS Europe as the master station, which supports FMS and DP protocols at the same time. This module is the main station of FMS and communicates with IPC and data acquisition system in master master mode; It is also a DP master station, which realizes master-slave communication with DCS500.
The data acquisition system adopts VXI bus technology to collect various parameters of the dynamometer and display them on the large screen, and form * * * results into tables and graphs (this part is completed by other companies). IPC communicates with data acquisition system through FMS. The composition of the whole system is shown in Fig. 2.
1.1 fieldbus PROFIBUS PROFIBUS is a standard developed by 13 companies such as Siemens and AEC and 5 scientific research institutions in the joint development project. It has been listed in the European standard en50170 and is one of the recommended industrial fieldbus standards in China. It includes the following forms:
·PROFIBUS FMS solves the general communication tasks at the workshop level provides a large number of communication services completes the cyclic and non cyclic communication tasks with medium transmission speed. The Profibus module of NAIS supports * * * communication rate of 1.2mbps and does not support cyclic communication mode it can only use MMA non cyclic data transmission master connection communication with other FMS master stations and this module is not compatible with PROFIBUS FMS of a * * * company therefore, one form of PROFIBUS cannot be used during scheme design.
·PROFIBUS PA the standard intrinsically safe transmission technology specially designed for process automation realizes the communication protocol specified in iec1158-2 and is used in places with high safety requirements and stations powered by the bus. The transmission medium used in the system is copper shielded twisted pair the communication protocol is RS485 and the communication rate is 500kbps. The application of industrial field bus provides guarantee for the safety and reliability of the system.
1.2 IPC industrial control computer
The upper industrial control computer adopts Advantech industrial control computer of Taiwan runs windows NT4.0 workstation operating system adopts WinCC industrial configuration software of Siemens large screen displays the operating conditions and quotation information of the system, and graphically shows the pipeline flow and blocking conditions. All data are transmitted by PLC via PROFIBUS. IPC is internally equipped with a profiboard network card produced by German softing company, which is specially designed for PROFIBUS. Through the configuration software provided by softing, networking can be completed, network communication relationship Cr (communication relationship) can be established, and object dictionary OD (object dictionary) can be established. WINCC is produced by Siemens. It only supports direct connection with S5 / S7 PLC of the company, and can only communicate with other PLC through DDE technology provided by windows. Software company provides DDE server software to realize PROFIBUS communication with WinCC.
１．３ PLC
Fp10sh of NAIS company is selected as PLC.
(2) control system function
In addition to controlling two water pump motors and two dynamometers, the control system also needs to control 28 electric valves, 4 weight motors, 8 oil pump motors, 3 vacuum pump motors, 4 oil discharge pump motors and 2 lubricating solenoid valves. The flow direction and flow of water are controlled by the valve switch to meet the test requirements of users.
2.1 constant head Adjust the rotation speed of the water pump: make it stable at a certain value, and the water head is constant at this time; Adjust the speed of the dynamometer to a certain value. After the working condition is stable for 2-4 minutes, collect relevant data. During the test, it is required to keep the water head unchanged. A code disk is placed on the pump motor to collect the motor speed, so that the DCS500 forms a closed-loop control. The water pump speed is input by IPC keyboard.
2.2 constant speed
Adjust the speed of the dynamometer to make it stable at a certain value, and the speed of the dynamometer is constant; Adjust the pump speed to a certain value (i.e. adjust the head), and collect relevant data after the working condition is stable for 2-4 minutes. DCS500 forms a closed loop for the speed of dynamometer to stabilize the speed of dynamometer.
2.3 runaway test
Adjust the speed of the dynamometer to a certain value and keep the speed of the dynamometer unchanged adjust the speed of the water pump so that the output torque of the dynamometer is approximately zero (under this working condition, the dynamometer operates for power generation and electric operation), and collect relevant data. During the test, the speed of the pump motor is required to be constant and regulated by DCS500.
2.4 flow calibration
The system is equipped with two flow correction tanks for calibrating the flow meters in the system. Before calibration, first determine the marked flow value, then start the water pump motor, and continuously adjust the rotation speed of the water pump motor. At this time, pay attention to the flow value. When the flow value reaches the required value, make the water pump motor stable at the current rotation speed (at this time, water circulates in the calibration pipeline). Set the switching time of the deflector. After the working condition is stable, turn on the solenoid valve and start the timing. At the same time, switch the water in the pipeline to the calibration tank. When the timing time is up, the solenoid valve is disconnected. At this time, the water is switched to the calibration pipeline, and the rotation speed of the water pump motor is reduced to stabilize at a certain speed. Read the relevant data. Then drain the water and calibrate the next point.
2.5 manual / automatic undisturbed switching
In order to facilitate the maintenance and debugging of the system, a manual keyboard is designed for the system. The operator can control the action of a certain valve independently through the keyboard without being constrained by the interlocking. The system adopts NAIS remote I / O module, which can make the keyboard operate in different places. During manual / automatic switching, the valve status remains unchanged.
The system adopts PLC as the main controller, which simplifies the system and ensures the high reliability and maintainability of the system; PROFIBUS realizes complete data transmission, avoids electromagnetic interference, and makes the system meet the design accuracy requirements; Data sharing between different devices is realized; The flexibility of PROFIBUS provides convenient conditions for system expansion. The system design scheme based on industrial field bus will become the mainstream of industrial application.
Post time: Aug-24-2022
