JPH0343874B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-linear regulation rate control device for an electric speed governor of a power plant that is used in connection with a power grid.

For power plants that are connected to the grid, the control method for spontaneous electricity differs depending on the relative power generation capacity of other systems. In other words, the main generator with a large capacity regulates the frequency of the grid, whereas the generator with a small capacity has a constant output (linked) operation that follows in conjunction with the governor opening of the main generator. and constant power operation that is completely unrelated to the control of the main generator, governor-free operation (two-stage broken line characteristic) and constant power operation (first-stage broken line characteristic) within the frequency fluctuation range specified for the grid.
Various operating methods are used, such as:

The present invention relates to a speed governor control device for obtaining a one-step broken line characteristic, which is generally referred to as a non-linear regulation rate characteristic, among the above-mentioned operating systems.

In order to obtain non-linear regulation rate characteristics, this type of conventional method uses a stiffness restoration setting section that changes the set value according to the governor opening degree to set the speed regulation rate of the generator as a non-linear characteristic. Ta. FIG. 1 shows a block diagram of a conventional governor control system, which uses a constant angle acceleration control system. In the same figure, the addition/subtraction value between the setting value of the speed setting part 1 and the setting value of the output setting part 2 is determined by the comparison part 3 by the rotation speed detection parts 5A and 5B of the generator 4.
is compared with the detected value. The rotation speed detection section 5A detects the rotation speed of the generator 4 as a pulse frequency, and the detection section 5B converts the pulse frequency into a voltage signal. The comparison result in the comparison section 3 is compared in the comparison section 6 with the setting value of the stiffness restoration setting section 7 whose setting value is determined according to the governor opening signal θ of the generator 4, and the deviation is calculated by the speed control operational amplifier section. 8 and is used as a speed control signal. This speed control signal is compared in a comparing section 9 with a detected value of an acceleration/deceleration detecting section 10 which inputs the detected values of the rotation speed detecting sections 5A and 5B, and the deviation thereof is calculated in an acceleration/deceleration control calculating section 11. The output of the calculation section 11 is compared with the detection section 13 of the governor opening signal θ in the comparison section 12, and the output is compared with the detection section 13 of the governor opening degree signal θ.
A governor opening minor loop is constructed that is used as an input.

In such a control device, the stiffness restoration setting section 7
If the characteristic is a non-linear characteristic, that is, by changing the amount of stiffness restoration, the speed regulation rate is made non-linear.
Therefore, in the loop that constitutes stiffness restoration,
The feedback amount of the stiffness restoration setting section 7 changes non-linearly with respect to the fixed constant of the forward transmission circuit constituted by the calculation sections 8, 11, 14 and the detection section 13. Since a change in the characteristic gain appears as a change in the gain of the control system, there is a limit to the gain of the nonlinear characteristic of the stiffness restoration setting section 7 in order to satisfy the stability condition of the system. Further, there is a problem in that the transfer function of the system changes depending on the change in the characteristics due to the stiffness restoration setting section 7 of the nonlinear characteristics. For this reason, in the conventional method, there are restrictions on the rate of change ΔF/ΔP of the characteristics at the broken line part, as shown in Figure 2, which shows the speed F _NA characteristics with respect to the generator output P _NA . There were drawbacks that placed restrictions on adjustment.

An object of the present invention is to provide a non-linear adjustment rate control device that can arbitrarily set the rate of change of the single-step broken line characteristic at the broken line portion and stabilize the system.

The present invention provides a nonlinear transfer function circuit in which the stiffness restoration setting section returns a constant value determined by a regulation rate to make the system including the stiffness restoration setting section a stable system, and whose characteristics can be changed to a return system of the generator frequency. The method is characterized in that an arbitrary one-step broken line non-linear adjustment rate can be obtained by providing the following.

FIG. 3 shows an embodiment of the invention. The same figure is the first
The difference from the diagram is that the generator rotational speed (frequency) feedback system is equipped with a nonlinear transfer function circuit consisting of an addition circuit 15 and a nonlinear adjustment rate setting section 16, and the stiffness restoration setting section 7 has linear input/output characteristics. It is in. A specific embodiment of the nonlinear transfer function circuit is shown in FIG. In the figure, R represents an operational resistor, SR represents a diode, and A ₁ to _{A 6} represent operational amplifiers. In the first adder circuit 17, the deviation between the voltage signal proportional to the system frequency from the detection section 5B and the set voltage of the system reference frequency setter ₁₆₁ is extracted with a gain of ₁ from the operational amplifier A1. This deviation signal is sent to a negative polarity bending point setting circuit 18 consisting of an operational amplifier A2 _, etc., an addition circuit 20 consisting of an amplifier _A4 , etc., and a positive polarity bending point setting circuit consisting of an amplifier _A3 , etc. It is used as a common input with the circuit 19. In the bending point setting circuit 18, the deviation signal input from the adder circuit 17 is the set value (positive) of the bending point setter ₁₆₂ .
When the deviation signal is at a negative absolute value exceeding the set value (negative) of the bending point setter ₁₆₃ , a positive polarity voltage is output with a gain of 1. Outputs a negative polarity voltage with a gain of 1. An adder circuit 20 which receives these deviation signals as an addition input uses an inverting circuit 21 comprising an amplifier _A5 etc. to polarize the added output of the amplifier _A4 , and a non-linear slope setter ₁₆₄ to adjust the gain. is set, and this output is used as the third amplifier consisting of amplifier _A6 etc.
The adder circuit 15 adds and inverts the output of the detector 5B. This output is fed back as a comparison input to the comparison section 3.

The operation of the non-linear adjustment rate setting section 16 having such a configuration will be explained with reference to FIG. 7. Set the voltage corresponding to the system reference frequency to the setting value of setting device 16 ₁ ,
When a fluctuation occurs in the actual system frequency (detection signal B),
The difference voltage is generated in the adder circuit 17 with opposite polarity. Now, if the grid frequency increases, adder circuit 1
A negative polarity voltage is generated at the output of 7, and the output of the bending point setting circuit 18 remains at zero unless this voltage exceeds the setting voltage of the setting device 16 ₂ +ΔF _NA . Conversely, when the system frequency falls below the setting value of the setting device 16 ₁ , the output of the bending point setting circuit 19 becomes zero unless the deviation voltage exceeds the setting value of the setting device 16 ₃ of the bending point setting circuit 19 - ΔF _NA1 . It is in. Therefore, for system frequency fluctuations in the setting range +ΔF _NA to −ΔF _NA1 , the total input value of adder circuit 20 is equal to that of adder circuit 1.
7, and the inverted output C of the inverting circuit 21.
is proportional to the output of the adder circuit 17 (the maximum is 1 depending on the setting of the setting device ₁₆₄ ), and the input of the adder circuit 15 is the system frequency signal B minus the output of the inverter circuit 21, which increases or decreases the generator frequency. The output D, which becomes the frequency feedback value, remains unchanged. In other words, the output is constant (the guide vane opening is constant) without any change in the governor opening. Further, when the setting value of the setting device ₁₆₄ is 1 or less, the output C changes as shown by C', and the operation is performed at the opening degree.

Next, when the system frequency α increases or decreases and exceeds the setting range +ΔF _NA to −ΔF _NA , the bending point setting circuits 18 and 19 also have outputs, which cancel the output of the adder circuit 17. Therefore, addition circuit 2
There is no change in the output of 0, the output C (or C') of the inverting circuit 21 becomes a constant value, and the output D of the adding circuit 15
(or D') has an output that changes in proportion to the change in generator frequency, which is a characteristic of governor-free operation.

Figure 5a shows the output B of the detection section 5B and the output C of the inversion circuit 21 for the above-mentioned set values +ΔF _NA and -ΔF _NA .
and the characteristics of the output D which is the sum of these, and the generator output _PNA and speed characteristics at that time can be obtained as a non-linear regulation rate characteristic of a one-step broken line, as shown by the solid line in Fig. 5b.

Next, if the setting device ₁₆₄ is set to the maximum value or less, the sixth
As shown in figure a, the slopes of outputs C and B are different,
The output D of the adder circuit 15 is within the setting range +ΔF _NA ~ΔF _NA
Within this range, it changes with an inclination corresponding to the change in B and C, and even within this range, it changes according to the frequency change of the generator, and the guide vane changes. The adjustment rate characteristic at this time is as shown in Figure 6b, which is the same as that of the conventional method.
It can be set to the same characteristics as shown in the figure.

As described above, the device of the present invention includes a nonlinear transfer function circuit in the generator speed feedback system that can change the characteristics from no output change within the set frequency range to the output change with the set gain, and the stiffness restoration setting section. Since the input/output characteristics are made direct characteristics, the system can be stabilized and any one-step nonlinear adjustment rate can be obtained.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the conventional control method, Fig. 2 is a conventional nonlinear regulation rate characteristic diagram, Fig. 3 is a block diagram of the method of the present invention, and Fig. 4 is the nonlinear transfer function circuit in Fig. 3. 5 and 6 are characteristic diagrams showing the control operation of the present invention, and FIG. 7 is a characteristic diagram of each part of FIG. 4. DESCRIPTION OF SYMBOLS 1... Speed setting part, 2... Output setting part, 4... Generator, 5A, 5B... Rotation speed detection part, 7... Rigidity restoration setting part, 8... Speed control arithmetic amplification part, 10... Acceleration/deceleration detection part, 11... Acceleration/deceleration control calculation unit, 13... Governor opening detection unit, 14... Governor opening control calculation amplifier unit, 16... Non-linear adjustment rate setting unit, 16 ₁ ... System reference frequency setter, 16 ₂ , 16 ₃ ... Bending point setting device,
16 ₄ ...Nonlinear slope setting device, 17...Addition circuit, 1
8, 19...Bending point setting circuit, 20... Adding circuit, 2
1...Inversion circuit.

Claims (1)

[Claims] 1. In controlling a generator used in connection with the grid to a non-linear regulation rate with a one-step broken line characteristic, rigidity restoration to obtain an output at a constant ratio determined by the regulation rate with respect to the governor opening of the generator A setting unit 7, a first addition circuit 17 that detects the deviation between the frequency detection signal of the generator and the system reference frequency, and a first bending point setting value that is set to be positive or negative, respectively, with the system reference frequency as the center. a pair of positive and negative inflection point setting circuits 18 and 19 which produce an output of zero when the deviation is small and obtain a difference output when the deviation is large, and each output of the inflection point setting circuit and the first addition circuit. an inverting circuit 21 which takes this output as an input and obtains an output proportional to the setting value of a non-linear slope setting device that determines the slope of the broken line characteristic; a third addition circuit 15 that adds the output of the inverting circuit to the detection signal to generate a generator speed detection signal; and a first comparison unit that obtains a deviation between the generator speed setting value and the speed detection signal. 3, a second comparison section 6 which obtains the deviation between the output of this comparison section and the output of the stiffness restoration setting section, and a speed control calculation performed from the output of this comparison section to obtain the control output of the governor opening degree. 1. A nonlinear regulation rate control device for an electric speed governor, comprising speed control units 8 to 14.