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300MW steam turbine electro-hydraulic control system of technological innovation

First, the project's background 1.1 300MW steam turbine electro-hydraulic control system Luoyang Shouyangshan Turbine Power Plant 2x300MW Hitachi TCDF-33.5 for the sub-critical pressure, reheat, double cylinder Exhaust, impulsivity, condensing steam turbine, in December 1995 and March 1996 production. Steam Turbine for the digital electro-hydraulic control system (D-EHG),[link widoczny dla zalogowanych], using low-pressure turbine oil DEH. Implementing agency is set to a high pressure oil motivated 4 HP control valve, 2 in the oil pressure in the pressure motivated two speed valve. Each hydraulic actuator controlled by a servo valve,[link widoczny dla zalogowanych], a steam turbine of the three hydraulic actuator (CV, left and right side of the ICV) of the servo valve are made in Japan Abex415 type servo valve. Control oil and lubricants are used the same oil source that is within the main tank turbine oil rust N32 number, in the control of oil on the road to install a sophisticated filter (accuracy 51μm). The first problem 1.2 LU Yang Power Plant Unit 3,4 trial operation started in 1995, the unit started the process often turn red oil phenomenon of motivation not move suddenly, after checking the normal control system,[link widoczny dla zalogowanych], normal signal transmission, both due to the servo valve failure,[link widoczny dla zalogowanych], valve replacement servo control system back to normal. Stable operation with a load unit and the pressure regulator inch Movement Test Date, there have motivation to move the case of oil and oil motive fully on or off phenomenon, check all servo valve failure. Faulty servo valve must be replaced, and this form of servo valve control system design can not be isolated, forced to stop change. Shouyangshan Power Plant Unit 3,4 causes the servo valve down: 2000, respectively 8, 5, 2001, respectively 1, 2; As of June 2002 for Unit 3 only because the servo causes the valve down to up to 4 times. The failure of the servo valve removed to check and found that its internal filter clogging, nozzles clogging, slide valve jam. Servo valve jam caused by the internal filter pre-level control servo valve pressure is too low, the eye can not control servo valve 2 stage piston movement, resulting in tripping the oil motive (for the control signal does not respond); nozzle clogging oil motive closed; servo VALVE, motivation to keep the oil in the fully open or fully closed position. Oil pollution is the main reason for the failure, caused by oil pollution, failure of servers VALVE servo valve failure accounted for 85% [1]. 1.3 oil condition and to prevent the servo valve jam measures the trial operation of Unit 3,4 often happens when the servo valve jam, the transfer of power plant after production of oil Shouyangshan attached great importance to 1996, set up a filter oil filter oil management classes to enhance and improve oil cleanliness. Frequency of servo valve jam when a test operation reduces a lot, but the number has more. Hitachi Two oil pipeline system is designed to form the casing, after the filter to the servo valve to control oil in the oil return line tubing can not be sampled in the monitoring, can only monitor the cleanliness of lubricants. According to the old No impurities (with a small amount of water for some time, very few check impurities). The new value NASl638 MOOG level or the provisions of the provisions of 8-9 6; some 300MW steam turbine lubrication system and the control system share a tank, but also with mineral turbine oil, then oil should be manufacturer of particle index of indicators available, the test cycle 6 months for each 1. Unit 2001, turbine oil samples 3,[link widoczny dla zalogowanych],4 speaking line particle analysis, were qualified to run the oil particle size (see Table 1). Servo valve jam caused by downtime, the safety impact on the unit is very large, and the servo valve jam caused by unplanned outage of the plant economy. Shouyangshan power plant has adopted the following provisional measures: (1) regular replacement of the servo valve, more than 3 months after the encounter down the replacement unit; (2) switch to control the oil filter on a regular basis, and the cleaning; (3) oil filter oil continuously improve the cleanliness of operation; (4) to strengthen oil test. From the run of view, the servo valve jam caused by reduction in the number down. But there is no fundamental solution to the problem, do the analysis, study and put forward a series of reform ideas, such as technically feasible and are abandoned. The multi-analysis, research, proposed modified servo valve, the choice of the strong performance of anti-pollution programs DDV valve. Second, Abex415 type servo valve 2.1 works electro-hydraulic servo valve is the conversion element, but also a power amplifier device, which the tiny electrical signals into hydraulic power energy output, the control valve of the valve speed. The performance of its advantages and disadvantages of the electro-hydraulic control system a great influence on electro-hydraulic control system is the core and key. The jet pipe servo valve for the second force feedback servo valve, the four-way valve, and its role is to control the oil out of the hydraulic system so that it is proportional to the input signal, mainly from the valve body, torque motor (coil, the armature) and permanent magnets, the first a jet pipe, the pressure feedback spring, level 2 spool valve, It works: a small amount of hydraulic oil from an oil origin by the filter, and then flows through the torque motor rotor connected to the hose, and finally out from the nozzle. Sprayed from the nozzle out of the oil pipeline to the two sets, the two pipes were connected to both ends of the slide valve. No offset, each set of tubing generate about half of the pipeline pressure, and thus have no pressure, so the slide valve balance. When current flows through the torque motor is a certain moment, the torque motor rotor turning a small angle. If the rotor is counter-clockwise rotation, the fuel injection pipe to the right, causing more oil spray to the right set of tubing, that is stressful, and the left have a smaller set of pressure tubing. This pressure difference appears on the slide valve, causing the slide valve to the left. Has been to the left until the slide valve return spring force and torque generated by the motor against the force generated is equal to date. Then slide valve in a new equilibrium position. Current proportional to level 2. Such as current of opposite polarity, then moved to the other side of the slide valve. 2.2 Features (1) the valve force feedback for the jet pipe servo valve secondary amplification; (2) low hysteresis, high resolution; (3) high sensitivity, good linearity and control of high precision; (4) The use of lubricating oil that is the same oil sources within the main tank turbine oil rust N32 number of oil is high and anti-pollution requirements of poor. 2.3 Technical specifications servo valve model, the parameters in Table 2.