JPS5815500A - Automatic voltage regulator - Google Patents

Abstract

PURPOSE:To remove a ripple and to reduce squaring circuits of an automatic voltage regulator by a method wherein a signal obtained by squaring respectively and adding the alpha voltage, and beta voltage calculated from the three phase AC voltage of generator voltage according to the alpha-beta-O method is made as the detection signal of generator voltage. CONSTITUTION:The generator voltage is converted into the proper level by a current transformer 3. Squaring circuits 7, 7 square respectively the alpha voltage Valpha shown with the expressionI, the beta voltage Vbeta=Vbc calculated according to line voltages Vab, Vbc of the generator. An operational amplifier 8 applies a deviation signal between the reference voltage Vref and the sum of outputs of the squaring circuits 7, 7 to an excitor. Accordingly the ripple contained in the detected voltage can be removed by the two squaring circuits.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic voltage regulator for controlling the terminal voltage of a synchronous generator.

There is a device as shown in FIG. 1 that automatically adjusts the voltage of a synchronous generator. In this case, the output voltage of the armature 1 of the generator is inputted to the automatic voltage regulator 5 via the transformer 3,
Here, the difference with the reference voltage is detected, and this difference is applied to the excitation device 6 to control the field voltage of the field winding 2 of the generator.
The generator voltage is controlled by the voltage regulator to a constant voltage determined by the reference voltage. The transformer 4 provides driving power for the excitation device 5.

The differential voltage detection circuit of the conventional automatic voltage regulator 5 is connected to the transformer 3.
The basic configuration is to perform three-phase full-wave rectification of the secondary voltage of the DC voltage and to compare and calculate this DC voltage with a reference voltage.

However, since the three-phase full-wave rectified DC voltage contains harmonics that are six times the frequency of the input voltage and its integral multiples as -f rL, a resistor is used to suppress this ripple component. 3 through a smoothing filter consisting of a capacitor and a capacitor.
After slipping by 1', compare with the reference voltage and detect the difference voltage [7
The reality is that This conventional technology (l-1) has the disadvantage that the response time of the automatic voltage regulator is slow because it requires the use of a smoothing filter as described above in the differential voltage detection circuit. It is difficult to remove ripples.

On the other hand, in order to ensure stable operation of electric power systems, automatic voltage regulators have recently become more and more rapidly adaptable.

To eliminate the above-mentioned conventional drawbacks, there is
There is No. 1.0100. As shown in Fig. 2, the secondary voltage of the transformer 3 for all phases is led to the square circuit 7 of -f: squared, and the difference between its output O and the reference voltage Er c f. Voltage Yr: Amplified by M amplifier 8, then Dih
The magnetic device 6 is used to pass magnetic voltage control signals. According to this paper, since there is no need to insert a smoothing filter to remove ripples, it is possible to obtain an automatic voltage regulator with a fast response time, but it requires three expensive squaring circuits 7. It has economic disadvantages.

The purpose of the present invention is to solve the above-mentioned second prior art. The purpose of the present invention is to provide an economical differential voltage detection circuit that eliminates the need for expensive two-way circuits without compromising high-speed response.

Therefore, in the second prior art, the line voltage V
nh , 'V lee , V , affi zo fl- zo l" L squared E, IQL-V ab"-1-'V 1
, c'+ V cn""... (1) and 17
Kyūdenki? In the present invention, the number of 1,2 circuits is reduced from three to two so that the 1Σ stress DC voltage Frdo is detected using a different method as follows.

Three phase voltages %; en, e, 1. eo, α−β−0
Letting ea be the α voltage and ea the β voltage according to the coordinate method, the following relational expression holds true.

Using these ea and ea, the generator voltage is detected as a direct current voltage Ed6L using the following equation.In other words, the number of square circuits can be reduced to two, and the configuration can be simplified.

E. , -e, , 2-1-ea2... curve... (4) This is the case where the three-phase voltage is balanced, so if 7 is equal, ea ""
ESln (W'+θo)-=・=・(5) It can be seen that the DC voltage is as follows.

-E2 ・・・・・・・・・・・・・・・・・・ (8
) On the other hand, since generator voltage is generally measured as line voltage rather than phase voltage, it is more convenient to derive equations (2) and (3) from line voltage. If equations (2) and (3) are modified to be derived from the line voltage, e
-Vllll ・・・・・・・・・・・・・・・ (
1-0) β-6. -I, line voltage~'b. It is even more convenient if the voltage is made to be the 1 sweet β voltage. That is, using the magnitude of the line voltage as a reference, the voltage and β voltage are expressed as (9) and (
10) Rewriting the equation as Vβ” V he ・・・・・・ ・・・・ (1
2), and the following equation obtained from this equation also becomes a DC voltage, as will be described later.

E d−t = V a”+ Vβ2・・・・・・・・・
...... (13) The basics of the present invention are (2
), (3), (4,) are used to detect voltage, and the following equations are derived from this formula: (1.1-), (1,2)
.

The circuit configuration is simpler when voltage is detected using equation (13).

An embodiment of the present invention will be described below with reference to FIG.

In Fig. 3, 3 is a transformer that converts the entire generator voltage to an appropriate level, and 7 is a transformer that inputs the values of equation (11) and substitution (12) (2) that produces an output that is proportional to the square of 7. Multiplier circuit, 8t, J, output sum of squarer circuit 7 and reference voltage 1'i
The operational amplifier 9 that detects and amplifies the difference between r and I is (
11) This is a level converter composed of a transformer, for example, for converting the constant 2/3 of the equation (2/3) to 4I.

Figure 3: In the differential voltage detection circuit of the automatic voltage regulator that has the same configuration as the one shown in Figure 3, is there any difference between the three-phase lines on the secondary side of the transformer 3? Ij
Pressure is V 1111 = Vsi++ (wt 10) song/song/
・If (14), then! 'Ifl's equation (13) is (11
) and (12), the following is obtained, and Edo[-Vr1'Vβ2 = -C-V2(1-C03(zWI+2θ)12 = v 2...・・・・・・・・・
(17) Edel is always constant regardless of time.

The armature voltage of the synchronous generator is the reference voltage E,. If it is equal to the set value of f, the sum of the square circuit 7 and the reference voltage E. Although there is no difference from f, the armature voltage of the synchronous generator is equal to the reference voltage E.
If r o varies from the set value of I, Edst in equation (7), which is the sum of the square circuit 7, also varies, so the reference voltage E r
A differential voltage is generated between s f and s f . This difference is Eds
(When <E r@f, it becomes positive and is amplified by the operational amplifier 8, fLfr, and then applied to the excitation device 6, bringing the field winding 2 in the direction of magnetization and increasing the generator armature voltage. On the other hand, E
When da t > E re I , the field winding 2 is moved in the demagnetizing direction to lower the generator armature voltage.

Through this operation, the generator voltage is controlled to be equal to the set value of Erel.

As a modification of the present invention shown in FIG. 3, the one shown in FIG. 4 can be considered. 31. 32 is a transformer that converts the generator voltage to an appropriate level, 9. Equation (11) is a square root circuit for taking the square root of the sum of the outputs of the square circuit, and 8 is the square root circuit output E d e t'. This is an operational amplifier that fully amplifies the voltage difference from the reference voltage Erol', and the same symbols as in FIG. 3 are the same functional elements.

In Fig. 4, E ds ,'= L t := v . . .
... (1-8) E re t' = F co
(19). As can be seen by comparing FIGS. 3 and 4, the transformer 3 is composed of two single-phase transformers 31.
It can be configured with 32 parts and is economical. Also, in FIG. 3, the output sums E de L and E of the square circuit. Since the differential voltage is obtained by comparing f, the differential voltage is obtained with a magnitude proportional to the gain (2), so it is easily affected by external noise, etc. In Fig. 4, the square root output bdet' and Er
e l"cT: Since the comparison is made, that is, the difference voltage is obtained by the magnitude proportional to (1) and I~, which has the advantage of being less susceptible to the influence of external noise, etc.

The differential voltage detection circuit according to the present invention for L5 is economical because it can reduce the conventional three square circuits to two, and it also has the same quick response time as the conventional one automatic voltage adjustment. All equipment can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an excitation NOSDEM when performing automatic voltage adjustment such as (171, synchronous start; FIG. 2 is a block diagram of a differential voltage detection circuit for a conventional automatic voltage regulator 7<, Fig. 3 is an example of a differential voltage detection circuit of the automatic voltage regulator of the present invention, and Fig. 4 is a block diagram showing a modification of Fig. 3. 1... Armature of a synchronous generator, 2 ... Field winding of synchronous generator, : 3 ... Transformer, 4 ... Transformer for excitation device, 5 ... Automatic voltage regulator, 6 ... Excitation device, 7.
...Squaring circuit, Figure I, Figure 2

Claims (1)

[Scope of Claims] 1. In an automatic voltage regulator that maintains a constant electric machine α voltage of a synchronous generator, a voltage regulator that detects the α voltage from the three-phase AC voltage of the armature voltage using the α-β-〇 coordinate method. a first detection circuit, a second detection circuit that detects the β voltage, a first and second square circuit that inputs the output of each detection circuit and obtains an output proportional to the square of the output; 1. An automatic voltage regulator, characterized in that it is completely equipped with an operational amplifier that obtains a slight difference between the sum of the outputs of the first and second square circuits and a predetermined voltage reference. 2. The first detection circuit according to claim 1 is supplied with an amount proportional to one line voltage of the three-phase AC voltage, and the second detection circuit is supplied with an amount proportional to one line voltage of the three-phase AC voltage. An automatic voltage regulator characterized in that it outputs an amount proportional to a composite voltage of two voltages and another line voltage. 3. An automatic voltage regulator characterized in that the operational amplifier according to claims 1 and 2 includes a square root circuit that obtains the square root of the sum of the outputs of the first and second square circuits.