Conventional HVDC system normal control mode

With the increasing power transmission and conveying distance scale gradually lengthened, the existing level ± 500kV DC transmission will not be able to meet the requirements, the objective need to adopt a higher level of DC transmission voltage levels. According to the Southwest Water outgoing transmission planning programs of research and related research conclusions combination of foreign, ± 800kV DC  Stainless steel needle valve feasible, more suitable for China's actual situation. In the conventional HVDC system's normal control mode, the rectifier side of the DC power required to calculate the dc current command, according to the current measurement value and the current value of the deviation obtained by proportional integral part of the firing angle to control the DC current while the commutation  Valve manifolds  tap slow  Trunnion ball valve  the firing angle as the reference value in the range of ± 2.5 °. Inverter side using constant extinction angle control, constant DC voltage control method combining with rectifier side HVDC control system together constitute the basic closed-loop control. ± 800kV DC transmission uses two 12-pulse inverter in series wiring, this wiring to make it run way more diverse.

Hydraulic systems in nuclear power plants has been widely used in a variety of non-return valve

Nuclear energy is energy efficient in the world energy mix has occupied the position can not be ignored , so the safety of nuclear power plants has also been referred to the new height . Nuclear power plants are large and complex hydraulic system hydraulic control system , the system is strictly prohibited countercurrent many locations phenomenon , or it may lead to serious accidents, therefore , require a lot of system -return element . Fluid control valve is an important safety  Stainless steel needle valve  , it is through closing fluid countercurrent to ensure directional flow of fluid , which protects other fluid machinery and pipeline safety . Therefore, in the nuclear power plant hydraulic system has been widely used in a variety of non-return valve , such as swing check valves . Swing check valve has a disc-type plug hinged on the edge , through the back off.  Trunnion ball valve design , low price, good economy , high reliability, easy maintenance and daily wide range of sizes , etc., the valve in the nuclear energy systems are widely used , the impact of the piston slam shut valve overpressure has been generated as experimental measurements and models to study the subject . Thus, the conventional movement of the check valve member (i.e., the valve head or valve ) to do the speed often rapidly opening and closing movement , the valve itself which is necessary features .

Butterfly cushion valve with automatic opening and self-closing feature

Butterfly cushion valve is general machinery products. Domestic production of butterfly cushion valve, the main structure of the same type and applies only in the sealing temperature differ. Butterfly cushion valve with automatic opening and self-closing  2 way manifolds  automatic valves, pressure loss also has shortcomings, is a traditional blast furnace  Instrument valve manifolds  supporting devices. In this paper, the technological transformation of check valves, check valves shall be  Trunnion ball valve  a control system, not only did not change the check valve automatically opens, auto-off function, but also it has the energy-saving features, while improving the prevention and control of non-return valve BF axial fan surge and counter functions....