Hydraulic part of governors and oil pressure units
The governor equipment made by Power Machines is operated in European, Asian, American and African countries. Today’s governors and oil pressure units are equipped with microprocessor control panels.
Electrohydraulic governors are used for controlling the speed and active power of the hydroelectric unit. The governor provides for the following operating modes:
- at idle;
- with an isolated load;
- with a high-capacity grid using opening feedback or power feedback;
- in synchronous compensator mode;
- in group operation mode, controlled by a central set-point adjuster;
- in water passage mode.
Power Machines manufactures governors for all hydroturbine types:
- Francis turbines;
- Kaplan turbines;
- Pelton turbines.
The electronic panel can be either standalone or integrated into the automated control system panels of the hydroelectric unit.
The hydromechanical part of the governor can be designed and manufactured for control system working pressures of 2.5 to 15 MPa. Hydromechanical control pillar or separate control unit versions are available. Control pillar versions with electrohydraulic control only and combined versions with electrohydraulic and mechanical control (linkage) are both manufactured. For large Kaplan and Francis turbines, columns and units with main slide valve diameters of 100 and 150 mm, designed for a maximum pressure of 6.3 MPa, are offered. BOSCH-REXROTH hydraulic equipment or equipment designed by Power Machines is used as electrohydraulic converters and slide valves.
Control pillars are installed separately from oil pressure units. Control units are installed on oil pressure unit drain tanks.
Feedback devices are installed directly on servo-motors; precise linear displacement transducers are used. The design does not include any links between moving and fixed components.
The speed signal generator consists of a toothed gear installed on the rotating part of the unit and a number of transducers. The device makes it possible to monitor speed in all operating conditions and to detect dangerously-low speed when the unit is at standstill.
Slide valves for emergency guide-vane closing are offered to ensure safe hydroelectric-unit operation. The valves are designed for a pressure of 6.3 MPa or less and have a diameter of 60, 100 or 150 mm. Slide valve control units utilizing 2-out-of-3 logic can be supplied.
A centrifugal overspeed protection device controlling the emergency slide valve of the guide vanes and closing the turbine guide vanes in case of unit overspeed is provided for the overspeed protection of hydroelectric units for all turbine types.
The hydromechanical part of the governor for low- and medium-capacity hydraulic turbines can be implemented as a single unit. It functions as a control pillar and an emergency slide valve and is designed using typical hydraulic equipment. The unit is installed on the pressure unit drain tank. For Kaplan turbines for a pressure of 15 MPa or less, Francis and Pelton turbines, higher pressure can also be used.
All designed and supplied equipment of the hydromechanical governor part is tested at the factory. The hydromechanical part of the governor is tested together with the standard control panel or a simulation unit.
- various types of hydraulic turbines;
- turbine generators;
- pre-turbine gate valves;
- automated control systems of hydraulic turbines;
- excitation systems and start-up frequency converters.
Power Machines not only supplies new governors and oil pressure units, but also carries out their replacement and modernization.
The governor includes:
- electronic microprocessor panel;
- hydromechanical control pillar or control unit;
- feedback unit;
- speed signal generator (SSG);
- emergency closing slide valve;
- centrifugal overspeed protection unit.
The oil pressure unit includes:
- control panel;
- hydraulic accumulator;
- oil pumping unit;
- leakage unit.