6 pressure compensation type governor hydraulic device and system features solution Su Xin 15! Water Resources and Hydropower Survey and Design Institute, Changsha City, 410007, Hunan Province, trough gas filling device, high pressure air compressor gas storage tank and its equipped pipe fittings and automation components, hydraulic turbine regulating system and flow to operate turbine guide vanes Perform load adjustment. This technology not only saves millions of dollars in equipment investment for the power station, but also reduces the maintenance and repair workload and operation and maintenance costs of the operating personnel, and also reduces the occurrence of safety accidents and improves the reliability of operation.
1 Overview The load of the power system is constantly changing. The change of the load will cause the system frequency to fluctuate. Therefore, the power output of the hydro-generator unit must be continuously adjusted according to the change of the load, and the speed of the turbine should be maintained within the specified range. This process is called turbine regulation. The way to adjust the turbine is to change the opening of the needle blade in the guide vane field. The governor system of the hydro-generator unit takes up this task. In the governor system, the hydraulic system is the operating system, and the opening of the guide vanes of the water guiding mechanism is operated by the actuator of the hydraulic operating system.
2 Conventional governor hydraulic device In the hydraulic system of the governor, the hydraulic device is a very important device. It consists of a pressure oil tank returning oil tank like a gear pump valve instrument. The pressure oil tank is an energy storage tank, which is the energy regulated by the water turbine. The volume in the pressure oil tank is 3040, which is turbine oil, and the remaining 6070 is compressed air. The pressure formed by the compressed air and oil is used to provide the unit for load regulation. The work effort required. The pressure oil of the pressure oil tank passes through the main pressure regulating valve of the amplifying component of the pipeline governor, to the relay of the turbine operating mechanism, and returns to the oil return tank. The pressure setting value and the oil level setting value are set on the pressure oil sump. When the turbine is under load regulation, when the oil consumed in the pressure oil tank drops to the oil level setting value, it is replenished by the oil pump; if the air leakage such as air leakage causes the pressure of the pressure oil tank to drop, it is composed of an electromagnetic air valve. The gas device is connected to the high pressure compressed air line and is supplemented by means of a special equipment high pressure gas tank to maintain the pressure of the pressure oil sump and a proportional amount of air. The automatic air supply can be easily realized by using the oil pump or the intake valve, but the efficiency is low, and it is only suitable for the small combined hydraulic device. Large oil pressure devices use gas storage tanks for qi, and the air after installation and maintenance are carried out by air compressors.
Therefore, in the design of large and medium-sized power stations, high-pressure air compressor high-pressure gas storage tanks and automatic components necessary for high-pressure compressed air systems are equipped.
3 Pressure-compensated hydraulic device 3.1 Structural composition The pressure-compensated hydraulic device is completely different from the above. It consists of an axial piston oil pump pressure compensating device, a fuel tank filter valve instrument and the like.
On the fuel collecting tank of the hydraulic device, two adjustable piston oil pumps are installed, and one working one is used. The oil pump is used to directly supply the working energy required for the unit to adjust, without the need to set a pressure oil sump. The pressure oil from the oil pump is passed through a proportional valve controlled by a programmable microcomputer governor to the servomotor of the turbine operating mechanism. The flow rate of each oil pump depends on the operating capacity of the unit operating the water guiding mechanism capacity + operating blade capacity. A single-stage pump can be selected for small operation capacity, and a multi-stage pump can be connected in series for large operation capacity. Each pump is driven by one motor regardless of the number of stages.
The pressure compensation device is called a pressure regulator for setting the flow regulation pressure of the pump, the pressure adjustment range is 335, and there are various options such as constant pressure control; constant power control; load detection control; pressure regulator remote control; pressure regulator parallel Run and so on.
The way in which the pressure compensating device and the adjustable piston pump operate in parallel is suitable for multi-stage pumps.
The filter is used to filter impurities in the oil to prevent blockage of the proportional valve and can be replaced during operation without downtime.
3.2 Working principle On the adjustable oil pump, an axial piston swash plate is designed. This swash plate is mainly used to move the applied load, and is a device for opening the liquid circuit. The flow rate of the pump output is proportional to the position of the swash plate, and there is no stepless change between zero and maximum output. The following is only a description of the working principle of constant power control, as attached.
Constant power control is actually controlling the output capacity of the pump relative to the operating pressure. Therefore, at a constant operating speed, the pre-set value of the power device cannot be exceeded, which is arbitrarily = constant, where it is a working pressure and 1 is the oil discharge.
The working pressure provides a force that acts on the rocker arm by controlling the inside of the piston. The external adjustment spring provides a force to the other side of the rocker arm. This force depends on the power setting value.
If the working pressure exceeds the set spring force, the pressure compensating device moves the oil passage of the piston 5 via the rocker arm operation control valve 3 to the working oil pressure, the oil pump rotates in the direction, the flow rate decreases, the swash plate is moved, and the movement is applied to the control piston. The load reduces the effective torque on the rocker arm. Similarly, when the output flow is reduced, the working pressure is also allowed to rise in the same proportion, and the corpus = constant makes the system reach equilibrium.
4 Operation The pressure-compensated hydraulic device and its governor hydraulic system have been in operation for more than 4 years in the Shangtan Hydropower Station in Hunan Province. It has been proved to be safe, stable and reliable after operation.
The Gaotan power station is a bulb tubular unit with a single-stage capacity of 19 MW, a rated head of 8.5 m and a turbine runner diameter of 5.3 m. The axial piston pump of the pressure-compensated hydraulic unit consists of stages, and the pressure compensation device operates in parallel with the oil pump. The operation mode is normal and stable operation of 1 unit. When the load is not adjusted, there is only pressure in the hydraulic system of the governor, no flow, that is, the oil in the oil pipe does not flow, actually due to oil leakage of some components such as solenoid valves and the pump itself. Lubrication, there are a small number of requirements inside the pump. The proportional valve is controlled by the governor control system. There is flow in the hydraulic system, that is, the oil flows and the pressure is reduced. At this time, the swash plate of the oil pump moves immediately, and the pressure is automatically adjusted. The flow rate makes the system reach the new when the oil pump does not run. When the pressure is zero, the swash plate returns to the starting position under the action of the spring, that is, the position of the maximum working capacity of the cylinder.
Since the system was in operation, the system has no faults and the equipment has no maintenance.
During the test operation, the unit did a quick shutdown test of the load test for no-load disturbance test. From the analysis of the waveforms automatically recorded by the computer, it can be seen whether the guide vanes are closed or closed, or the length of the closing time is set. They are all smooth, indicating that the servomotor has no swing, the oil pressure is stable, and the oil pump meets the requirements of the regulating system.
5 system equipment features The governor hydraulic system consisting of pressure-compensated hydraulic devices has the following characteristics: 1 cancels the pressure oil sump of the conventional governor hydraulic device; 2 eliminates the high-pressure compressed air system configured for the pressure oil sump; 8 saves The equipment investment includes 2 sets of high-pressure air compressors, 1 high-pressure gas tank, gas-water separator, valve, pipe fittings, auto parts, equipment, installation and transportation costs, and the civil works cost of the equipment required for the plant, millions of yuan; 4 reduced equipment maintenance Maintenance costs and equipment accident rate; 5 simplifies the design, at the same time the equipment structure is compact, the pipeline is reduced, the plant layout is more neat and beautiful, and the operation management is more convenient.
6 Conclusion Adjustable piston oil pump pressure compensation hydraulic device is the pressure energy of the turbine operating mechanism. It breaks the oil and gas mode of the traditional hydraulic device. It is innovative in terms of thinking, and has good research application and promotion value.
Manuscript 2,001013 Responsible Editor Yan Yanfang
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