Car governor is in automatic operation state during the production and operation of the power station, which requires microcomputer to control the pilot drive components, as shown in Figure 3. As shown in Figure 4, the secondary hydraulic amplification is realized to drive the guide (wheel) blade relay. The speed produced by the relay is called the electrical speed of the speed regulating system, which is recorded as VE.
In the final analysis, the electrical speed of the car governor is based on the mechanical speed, and the quality of the electrical regulation is based on the mechanical hydraulic pressure. It can be said that electricity is a mechanical aid. Because the final object of the electrical action is the main configuration of the governor, and after the adjustment of the main switch nut, the basic speed VM of the governor system relay has been determined.
Therefore, no matter how to adjust the electric speed VE of the car governor, it will not exceed the mechanical speed VM of the car governor, that is VE<=VM.
Whether it is the mechanical speed VM of the car governor or the electrical speed VE of the governing system, they must meet the speed required for the calculation of the regulation and protection of the hydro-generator set.
Therefore, when adjusting the electric speed of the governing system, it is necessary to adjust the electric control parameters of the pilot device carefully so that VE can meet the speed requirement of the calculation of the regulation and protection of the system.
This is another important test of the water-free debugging of the governing system of hydraulic turbines. The ultimate goal of the test is theoretically to reach VE = VM, even if it cannot be adjusted to the end. All equal, we must make the two infinitely close, so that we can truly achieve mechanical and electrical integration.
The quality of electric speed adjustment of the speed regulating system is directly related to the automation level of car governor and affects the economic and stable operation of hydropower generating the set. Therefore, we must pay enough attention to it.
A large amount of power generated by power plants cannot be stored entirely, if not properly managed, it may cause a waste of power resources. So steam turbines generally have automatic speed governing the system.
However, in the process of self-regulating operation of 600 MW steam turbine, it may cause the fluctuation of steam turbine caused by too fast rotational speed, which will affect the normal operation and power production.
Therefore, it is necessary to adjust the rotational speed of the car governor to ensure the normal operation of the steam turbine.
Main functions of turbine car governor:
(1), to meet the needs of power supply in power plants
Customer’s power demand affects the power supply of power plants. Because the power demand is dynamic, there is no fixed demand, and the power demand fluctuates greatly in different periods of time, if there is no corresponding car governor to adjust the load of the turbine, the turbine load will be too large, affecting the turbine. Normal operation, or even outage, cannot meet the demand for electricity, thereby reducing the production efficiency of power plants.
(2), effectively guarantee the power supply quality of power plants
In order to ensure the quality of power supply in power plants, two aspects should be taken into consideration. One is to ensure a stable voltage, which is mainly handled by transformers to ensure the normal and stable output voltage; the other is to ensure the normal frequency of the grid, which is determined by the rotational speed of the steam turbine and its stability. The equilibrium rotation speed is the key factor for the normal frequency of the grid.
(3), to ensure the safety of power plants
The centrifugal force on the inner impeller and blade of a steam turbine in a power plant will increase exponentially with the increase of rotational speed.
When the centrifugal force reaches or exceeds a certain rotational speed limit, the excessive centrifugal force will damage some internal components, resulting in a larger production accident and power generation. The company has brought huge economic losses.
Installing car governor in the steam turbine can effectively ensure the rotating speed of steam turbine generator set to run in a safe range and avoid safety accidents.