Hydraulic turbine model test bench 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. The production of any runner must first develop a model runner and test the model by simulating the actual head meters of the hydropower station on the high head hydraulic machinery test-bed. If all the data meet the requirements of users, the runner can be officially produced. Therefore, some foreign hydropower equipment manufacturers have several high water head test benches to meet the needs of various functions. For example, France’s neyrpic company has five advanced high-precision model test benches; Hitachi and Toshiba have five model test stands with a water head of more than 50m. According to the needs of production, a large electrical machinery research institute has designed a high water head test-bed with full functions and high precision, which can carry out model tests on tubular, mixed flow, axial flow and reversible hydraulic machinery respectively, and 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 fieldbus technology to realize the advanced all digital control mode, which ensures the reliability, safety and easy maintenance of the system. It is a water conservancy machinery test control system with high degree of automation in China. Composition of control system
The high water head test bench consists of two pump motors with a power of 550KW and a speed range of 250 ~ 1100r / min, which accelerate the water flow in the pipeline to the water head meters 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, the speed is between 300 ~ 2300r / min, and there is one dynamometer at stations a and B. The principle of high head hydraulic machinery test bench is shown in Figure 1. The system requires that the motor control accuracy is less than 0.5% and the MTBF is greater than 5000 hours. After a lot of research, DCS500 DC speed regulation system produced by a * * * company is selected. DCS500 can receive control commands in two ways. One is to receive 4 ~ 20mA signals to meet the speed requirements; The second is to add PROFIBUS DP module to receive in digital mode to meet the speed requirements. The first method has simple control and low price, but it will be disturbed in current transmission and affect the control accuracy; Although the second method is expensive, it can ensure the accuracy of data and control accuracy in the transmission process. Therefore, the system adopts 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 water pump motor, transmits the motor running speed to DCS500 through PROFIBUS DP, and obtains the motor running state and parameters from DCS500.
PLC selects the afp37911 module produced by NAIS Europe as the master station, which supports FMS and DP protocols at the same time. The module is the main station of FMS, which realizes the main main mode communication with IPC and data acquisition system; It is also the DP master station, which realizes master-slave communication with DCS500.
All parameters of the dynamometer will be collected and displayed on the screen through VXI Bus Technology (other parameters will be collected by VXI company). IPC connects with data acquisition system through FMS to complete communication. The composition of the whole system is shown in Figure 2.
1.1 fieldbus PROFIBUS is a standard formulated by 13 companies and 5 scientific research institutions in the joint development project. It has been listed in the European standard en50170 and is one of the industrial fieldbus standards recommended in China. It includes the following forms:
·PROFIBUS FMS solves the general communication tasks at workshop level, provides a large number of communication services, and completes the cyclic and non cyclic communication tasks with medium transmission speed. The Profibus module of NAIS supports the communication rate of 1.2mbps and does not support the cyclic communication mode. It can only communicate with other FMS master stations by using MMA non cyclic data transmission master connection and the module is not compatible with FMS. Therefore, it cannot only use one form of PROFIBUS in scheme design.
·PROFIBUS-DP optimized high-speed and cheap communication connection is designed for communication between automatic control system and equipment level decentralized I / O. Because DP and FMS adopt the same communication protocol, they can coexist in the same network segment. Between NAIS and a, msaz non cyclic data transmission master-slave connection slave station does not actively communicate.
·PROFIBUS PA standard intrinsically safe transmission technology specially designed for process automation realizes the communication procedures specified in iec1158-2 for occasions 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 fieldbus provides a guarantee for the safety and reliability of the system.
1.2 IPC industrial control computer
The upper industrial control computer adopts Taiwan Advantech industrial control computer running Windows NT4 0 workstation operating system WinCC industrial configuration software of Siemens company is used to display the operating condition information of the system on the large screen, and graphically represent the pipeline flow and blockage. All data is transmitted from 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 relation) and object dictionary OD (object dictionary) can be established. WINCC is produced by Siemens. It only supports direct connection with the company’s S5 / S7 PLC, and can only communicate with other PLCs through DDE technology provided by windows. Softing 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 functions
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 drain pump motors and 2 lubrication solenoid valves. The flow direction and flow of water are controlled through the switch of valves to meet the test requirements of users.
2.1 constant head
Adjust the speed of water pump: make it stable at a certain value, and the water head is certain at this time; Adjust the speed of the dynamometer to a certain value, and collect relevant data after the working condition is stable for 2 ~ 4 minutes. During the test, it is required to keep the water head unchanged. A code disk is placed on the water pump motor to collect the motor speed, so that DCS500 forms a closed-loop control. The speed of water pump is input by IPC keyboard.
2.2 constant speed
Adjust the speed of the dynamometer to make it stable at a certain value. At this time, 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 to make the output torque of the dynamometer close to 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 water pump motor is required to remain unchanged and adjusted by DCS500.
2.4 flow calibration
The system is equipped with two flow correction tanks for calibrating the flowmeter in the system. Before calibration, first determine the marked flow value, then start the water pump motor and continuously adjust the speed of the water pump motor. At this time, pay attention to the flow value. When the flow value reaches the required value, stabilize the water pump motor at the current 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, start timing, and switch the water in the pipeline to the correction tank at the same time. When the timing time is up, the solenoid valve is disconnected. At this time, the water is switched to the calibration pipeline again. Reduce the speed of the water pump motor, stabilize it at a certain speed, and read 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 valve independently through the keyboard, which is not constrained by interlocking. The system adopts NAIS remote I / O module, which can make the keyboard operate in different places. During manual / automatic switching, the valve state remains unchanged.
The system adopts PLC as the main controller, which simplifies the system and ensures the high reliability and easy maintenance of the system; PROFIBUS realizes complete data transmission, avoids electromagnetic interference, and makes the system meet the accuracy requirements of the design; Data sharing between different devices is realized; The flexibility of PROFIBUS provides convenient conditions for the expansion of the system. The system design scheme with industrial fieldbus as the core will become the mainstream of industrial application.
Post time: Feb-17-2022
