JPS6236478B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In recent years, high-performance water turbine governors have been widely adopted from the viewpoint of supplying high-quality electric power. In particular, conventional speed governors have limitations in stability and quick response, so various improvements have been made, one of which is
A PID control governor is used. As shown in Figure 1, the PID type governor has a proportional element P, an integral element I,
This is the so-called differential element D connected in parallel.
The rationality of the PID controller is introduced into the water turbine governor. Each element of the PID can be set independently, and the effect of the differential element ensures quick response and stability.

Here, in Fig. 1, 1 to 3 are PID controllers,
4 is a power amplifier, 5 is an auxiliary servo, and 6 is a speed droop rate setting device. When the deviation between the rotational speed signal of the water turbine and the speed setting device is △N, the speed deviation signal △N and the speed droop rate feedback signal maintain equilibrium in the steady state during governor operation, and the integrator 2 always A signal corresponding to the guide vane opening is maintained, but if the guide vane is controlled in the closing direction from a balanced state using a single load limiter, etc., the speed droop rate feedback signal amount decreases, and the speed governor changes to the guide vane opening direction. issue control commands. Therefore, as shown in Fig. 2, if the horizontal axis represents the guide vane opening and the vertical axis represents the integrator output, the load limiter will move from a balanced state at point b during speed control operation to, for example, point a. When the guide vane is moved in the closing direction, the output of the integrator will rise to the electrical upper limit if left as is due to the open command. FIG. 3 shows a time chart when the load is interrupted. When time is plotted on the horizontal axis, the breaker 52 turns OFF when the load is interrupted, as shown by the solid line.
Then, the water turbine rotation speed No increases due to the input/output energy imbalance, and the integrator output V _I starts to decrease due to the rotation speed deviation △N, which is the PID input, but since the integrator output is at the upper limit value V _Inax , In fact, the governor's command C is delayed in issuing the guide vane closing command, which greatly affects the immobility time, resulting in a very large increase in the main engine rotational speed No. In addition,
V _IOL indicates the value equivalent to the guide vane opening before the load sheath breaks.

Also, when comparing the change in the rotation speed of the water turbine and the change in the integrator output when the load is interrupted, the governor issues a command to close the guide vane as the rotation speed of the water turbine increases, but in reality the rotation speed of the water turbine increases. does not decrease immediately;
A decreasing signal is given to the integrator until the water turbine rotation speed reaches a certain value, and as a result, the integrator output is lower than the no-load opening equivalent value V _INL , and may even become a negative output. Therefore, the rotational speed of the water turbine will now drop below the no-load rotational speed, and it will take a long time to return to normal.

An object of the present invention is to provide a water turbine governor with excellent stability and quick response by controlling the upper limiter value of an integrator in PID control.

FIG. 4 shows an embodiment of the present invention, and the same parts as in FIG. 1 are designated by the same numbers. PID controller integrator 2
With the output of and the feedback signal of the auxiliary servo motor 5,
The output signal of the upper limit deviation setter 7, which changes the upper limit limiter value of the integrator 2, is input to the integral limiter 8, and the integrator upper limit value shown by the two-dot chain line is set for the characteristic during the regulating operation shown by the solid line A in Fig. 5. Obtain the limiter value V _LH , and use the output of the integrator 2 as the input of the integrator limiter 8, and set the integrator lower limit value V _LL shown by the two-dot chain line in Fig. 5 to be constant regardless of the position of the auxiliary servo motor. The characteristics obtained are as follows. As a result, Kushiya disconnector 52 is OFF as shown by the dotted line in Figure 3.
Since the output value V _LH of the integrator 2 always has a guide vane equivalent value even during input unbalance such as load limit operation, the governor issues the guide vane closing command only during governor operation. Since this can be done in the same amount of time as , the increase in the number of rotations of the water turbine can be kept low. Also, even if the water turbine rotation speed decreases slowly relative to the governor command, the output of the integrator 2 will be applied to the lower limiter, so it will not fall below a certain value, and the water turbine rotation speed will be kept to a minimum below the specified value. can be kept to a limit.

Here, FIG. 6 shows a specific example of the integrator 2, upper limit deviation setter 7, and integrator limiter 8 in FIG. 4. 9 is an operational amplifier, 10 is a capacitor, 11 is a resistor, 12 is a diode, 13
is a variable resistor. OA1 constitutes an integrator by using a resistor R1 and a capacitor C1. If the output of this integrator is within the range of the two-dot chain line shown in Fig. 4, the input resistor R1 of OA3
Since the voltages divided by 5, R16 and R17, R18 are cut off by diodes D1, D2, no voltage appears at the output of OA3.
Here, assuming that the integrator output increase signal is input to the input, the sum of the upper limit deviation value determined by the guide vane opening degree feedback signal and variable resistor VR1 and the integrator output value is the input resistor R17 of OA3. ，
When the voltage is about to exceed the value divided by R18, diode D2 becomes conductive, and the output of OA3 acts to cancel the input signal of the integrator and stops on the two-dot chain line in Figure 5. . Also, assuming that the integrator output reduction signal is input to the input, OA
When the integrator output is about to drop below the value divided by the input resistors R15 and R16 of 3, the diode D1 becomes conductive and an output that cancels the integrator input is generated at OA3, and as shown in FIG. As shown by the dotted chain line, it is determined to be a constant value regardless of the guide vane opening degree.

Here, according to the present invention, the deviation amount of the integrator upper limiter value is made variable according to the guide vane opening degree, but by fixing the set value voltage of VR1 in FIG. 6, the deviation amount can be made constant. can be done and obtain the same effect.

As explained above, according to the present invention, stability,
It is possible to replace a conventional speed governor with a highly responsive PID control governor without changing the operating method or interface.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the PID control system governor, Figure 2
Figure 3 is a diagram of the operation of the integrator during load limit operation, Figure 3 is a diagram of changes in the number of rotations of the water turbine when the load is interrupted, Figure 4 is a governor block diagram with an integrator limiter added, and Figure 5 is a diagram of the speed governor with an integrator limiter added.
The figure is a diagram for explaining the integrator limiter characteristics with respect to the guide vane opening degree signal, and FIG. 6 shows an embodiment of the present invention. 1... Proportional element, 2... Integral element, 3... Differential element, 4... Power amplifier, 5... Auxiliary servo motor, 6... Speed droop rate setter, 7... Upper limit deviation setter, 8... ...Integrator limiter.

Claims (1)

[Claims] 1 Feed back the opening degree of the turbine guide vane, obtain the speed droop rate feedback signal from the guide vane opening degree via the speed droop rate setter, compare the speed droop rate feedback signal and the speed deviation signal, and input the proportional integral regulator. and in a water turbine governor that controls the opening degree of the water turbine guide vane by the output of the proportional integral regulator, means for changing an upper limit value of an integral element of the proportional integral regulator according to the opening degree of the guide vane. A water turbine speed governor characterized in that the integral element output is maintained at a value corresponding to the guide vane opening degree when the speed governor input signal is unbalanced.