JPH0356100A - Exciting method and exciting equipment of generator - Google Patents

Abstract

PURPOSE:To improve AVR control accuracy by detecting a physical quantity of a field exciting system fluctuating according to exciting power supply voltage and feeding back the detected physical quantity negatively in order to correct an AVR control signal. CONSTITUTION:Output voltage from the armature 1 of a generator is detected via a voltage transformer 6 and the difference between the output voltage and a reference voltage VREF is operated by an AVR operating part 11. An exciting equipment main body 4 is driven by the output of the AVR operating part via a gate pulse generating part 12 to control the field current to be fed to a field winding 2. The field current is detected by a current transformer 7a, rectified and inputted into a field current feedback control part 13 where it is operated. The output thereof is subtracted from the output of the AVR operating part 11 and inputted to the gate pulse generating part 12. In other words, the stability of AVR control is improved by adding the field current control as a minor loop.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a generator excitation method and an excitation device, and particularly to suppressing fluctuations in the generator output caused by power supply voltage fluctuations of the excitation device, and furthermore, relates to a technique suitable for suppressing fluctuations in an electric power system.

[Conventional technology]

Generally, the output voltage control of a generator is performed by determining the deviation between the output voltage and the reference voltage using an automatic voltage regulator (hereinafter referred to as AVR), and outputting a control command to the excitation device to reduce this deviation to zero. Methods of adjusting field current are known.

For example, a magazine (Thermal Nuclear Power Generation: "Instrumentation, Control and Automation" pages 86-88, published June 20, 1982)
According to what is described in , the firing phase of the thyristor excitation device is controlled by the AVR according to the above deviation, thereby adjusting the field current to maintain the generator output voltage at the reference voltage. .

[Problem to be solved by the invention]

However, since the above-mentioned conventional technology does not take into account the influence of fluctuations in the power supply voltage of the excitation device, there is a problem of control errors in which the output voltage of the generator fluctuates in accordance with fluctuations in the excitation power supply voltage. This problem leads to the generation of reactive power.

That is, fluctuations in the excitation power supply voltage generally have a long period (for example, about IHz or less), and cannot be removed by a normal AVR gain. Conversely, if the AVR gain is simply increased in order to remove it, a problem arises in that the stability of the power system decreases.

Also, from the point of view of power system stabilization,
-36199, the system stabilization device (hereinafter referred to as PSS)
This paper describes a technique for suppressing power fluctuations near the dynamic stability limit by feeding back the field current to the dynamic stability limit.

However, since the technology disclosed in the publication is primarily concerned with suppressing power fluctuations, it has characteristics that respond to fluctuations in the field current in a frequency band of at least I Hz or higher, and the technology responds to fluctuations in the field current in a frequency band of at least I Hz or higher. It is not possible to cope with long-period steady fluctuations such as fluctuations, and it is not possible to reduce fluctuations in the output voltage caused by such fluctuations.

An object of the present invention is to provide a generator excitation method and an excitation device that can reduce control errors caused by fluctuations in excitation power supply voltage.

In addition to the above objects, another object is to provide a generator excitation method and an excitation device that can suppress fluctuations in the power system with a simple configuration.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a method for exciting a generator, which includes detecting a deviation between the output voltage of the generator and a reference voltage, and controlling the field of the generator so that this deviation becomes zero. The present invention is characterized in that the field current of the generator or the quantity of electricity corresponding to the field current is detected, and the detected value is negatively fed back to correct the field control amount.

Note that the correction of the field control amount can be set to a correction amount that suppresses fluctuations in the excitation power supply voltage and/or fluctuations in the power system.

Furthermore, the device of the present invention that implements the above method is a generator excitation device that includes automatic voltage adjustment means that determines the field control amount of the generator in order to make the output voltage of the generator match the reference voltage. The present invention is characterized in that it is provided with a field current detection means for detecting the field current of the machine or an electric quantity equivalent thereto, and a field current feedback correction means for correcting the field control amount by negatively feeding back this detected amount. .

Note that the field current feedback correction means may have a transfer function that includes at least one of an element that suppresses voltage fluctuations of the excitation device and an element that suppresses fluctuations in the power system. .

Further, another excitation method of the present invention is a generator excitation method comprising controlling the field of the generator according to the deviation so that the output voltage of the generator matches the reference voltage. The present invention is characterized in that the amount of variation in the excitation power supply voltage that supplies field power is detected, and the field control amount is corrected so as to make the detected amount of variation zero.

Further, the device of the present invention for carrying out the other method described above includes an excitation device main body and an automatic voltage regulator, and the automatic voltage regulator receives the output voltage of the generator and converts this output voltage into a reference voltage. A field control amount is determined according to the deviation so as to match the field control amount, and the excitation device main body is configured to input the field control amount and supply a field current to the generator according to the field control amount. The excitation device for a generator is characterized by comprising means for detecting fluctuations in the power supply voltage of the excitation device main body and correcting the field control amount so as to reduce fluctuations in the field current due to fluctuations in the power supply voltage. do.

〔Example〕

Hereinafter, the present invention will be explained based on examples.

FIG. 1 shows the overall structure of an embodiment of a generator excitation device and an automatic voltage regulator (AVR) to which the present invention is applied.

The generator includes an armature 1 and a field winding 2.

Armature 1 is connected to the power grid via main transformer 3. Field volume Is! Reference numeral 2 is connected to the output end of an excitation device main body (hereinafter simply referred to as an excitation device) 4 made of a thyristor rectifier. An input end of the excitation device 4 is connected to an in-house power supply system as an excitation power source via an excitation transformer 5, and is configured to convert alternating current power into direct current and supply it to the field winding 2.

AVRIO includes an automatic voltage regulation (AVR) calculation section 11, a gate pulse generation section 12, and a field current feedback calculation section 13. The AVR calculation unit 11 generates or outputs a control signal Vt corresponding to a field control amount that causes the generator output voltage VG to match a target reference value VREF. The output voltage VG required for this process is detected by a voltage transformer (PT) 6 connected to the output terminal of the armature 1. Further, the deviation ΔVa between the output voltage Vc and the reference voltage VREF is obtained by the adder 14 and is obtained by the AVR calculation unit ↓
1 is input.

The AVR control signal Vr is input to the gate Hals generation section 12 via the adder 15. The gate pulse generator 12 generates a gate pulse signal Pa having a phase timing according to a predetermined relationship between v■ and the firing angle, and outputs it to the excitation device H4.

In addition. The relationship between Vr and firing angle is determined based on the fact that the excitation power supply voltage is constant. The thyristor of the excitation device 4 is controlled to fire by the gate pulse signal pa,
As a result, the field current I is adjusted so that the deviation ΔVa becomes zero.
F is adjusted.

On the other hand, the field current feedback calculation section 13 negatively feeds back the field current IF to the AVR control signal Vl via the adder 15, thereby minimizing fluctuations in the field current due to fluctuations in the excitation power supply voltage.

The field current IF required for this negative feedback is detected by a field current detector 7 consisting of a current transformer (CT) 7a and a rectifier 7b provided on the primary side of the excitation device 4, and the field current feedback calculation is performed. The information is input to section 13.

The arithmetic unit 13 performs gain adjustment and phase adjustment on the negative feedback signal, and inputs the resultant signal to the (-) end of the adder 15.

The detailed configuration of this embodiment will be explained below along with its operation. first. The main loop of AVH will be explained. Note that this main loop has the same structure as conventionally known, and the fluctuation ΔIF of the field current IF due to the fluctuation ΔVT of the excitation power supply voltage Vr is as follows.
It is expressed by the following formula (1).

Here, Ka...gain K of the gate pulse generator 12
t...Gain RF of the excitation device 4...Resistance of the field winding As is clear from equation (1), the field current IF varies in proportion to the excitation power supply voltage fluctuation ΔVT. Correspondingly, the output voltage Va of the generator also changes.

In contrast, by providing a field current feedback loop, which is a feature of this embodiment, the field current IF corresponding to equation (1) is
The variation ΔIF is expressed by the following equation (2).

Here, KF2... Gain of field current feedback calculation unit 13 VT1... Excitation power supply voltage (standardized value) before fluctuation VT,
...In the excitation power supply voltage (standardized value) formula (2) after fluctuation, generally KG - K = 2 to 3, and if KF2 is about 3, Vt is around 1 and from Luke to KF, ・KO-
It can be said that KT-Vtz>1. Therefore, it can be regarded as ΔIF:O, and the influence of fluctuations in the excitation power supply voltage can be minimized.

As mentioned above, when negative feedback of the field current is applied to the AVR system, the constant gain of the control system from the AVR control signal 1 to the field current IF becomes approximately 1/KF. Therefore, in order to make the forward gain of the main loop the same as before,
The gain KF of the AVR calculation unit l1 is KG-K compared to the conventional one.
Compensate the gain by doubling T-KF.

On the other hand, if the stability of the power system decreases for some reason and power fluctuations occur, the power fluctuations and the field current IF of the co-worker phase will fluctuate due to armature reaction. Conventionally, this variation was suppressed by PSS, but as in this embodiment. If a negative feedback system for field current is provided in the AVR system, power fluctuations can be stabilized by the AVR, regardless of PSS. In this case, field current feedback calculation section 1
Assume that the transfer function F2(S) of 3 is shown in the following equation (3).

The first term on the right side of equation (3) is an element related to removing fluctuations in the excitation power supply voltage VT, and the second term is an element related to suppressing power fluctuations. The constants T1 to T in the second term are selected to values suitable for stabilizing the power system and improving transient characteristics.

As described above, according to this embodiment, one field current negative feedback loop can improve the accuracy of output voltage control due to fluctuations in excitation power supply voltage and suppress power fluctuations. According to the experiment of this embodiment, even if the excitation power supply voltage VT fluctuated by about 30%, the control error of the output voltage could be kept at 0.1% or less. This is the conventional control g! under the same conditions. Approximately 1 difference in JX
/10 or less, which has the effect of sufficiently improving control accuracy against excitation power supply voltage fluctuations.

In addition, since there is an effect of controlling power fluctuation, a highly reliable and inexpensive excitation control device can be realized.

In the embodiment shown in FIG. 1, the field current I is used as the negative feedback signal.
Although F is used, the same effect on control errors can be obtained by using the field voltage VF instead. However, when using the field voltage VF, there are disadvantages such as the need for a special converter with high withstand voltage and high ripple for the detection unit, and the need to take into account temperature fluctuations in the field resistance RF. be.

The field current IP can also be detected by inserting a shunt resistor into the DC circuit on the secondary side of the excitation device 4.

In addition, in order to minimize the influence when the amount of negative feedback becomes abnormal due to a failure of the field current detector 7 or the field current feedback calculation unit 13 itself, the output terminal of the field current feedback calculation unit 13 is It is desirable to provide a limiter. Furthermore, such a failure in the field current feedback system will substantially increase the forward gain of the AVR system, so although the control error will not change, the control system will become unstable. It is desirable to reduce the gain of the section 11 to a condition without negative field current feedback.

Additionally, AVR7 can be configured using a digital computer. This has the advantage that it is not affected by disturbances such as noise and that the gain can be easily changed.

In addition, although the example shown in FIG. 1 shows an example in which the excitation power source is obtained from the in-house power supply, the same effect can be obtained even if the excitation power source is obtained directly from the generator as shown in FIG. I can do it. Furthermore, it is naturally applicable even if the generator is a superconducting generator.

FIG. 3 shows the overall structure of another embodiment of the present invention. 1st
The example shown in the figure shows the influence of the excitation power supply voltage fluctuation ΔVT,
This was compensated by negative feedback of the field current IF. This embodiment attempts to compensate by directly correcting the firing angle of the thyristor in accordance with the fluctuation ΔVT of the excitation power supply voltage.

Therefore, in this embodiment, as shown in FIG.
T is determined, and the firing angle, that is, the gate pulse P, is determined accordingly.
The field current IF is controlled to a value corresponding to VI by correcting the phase of a.

Therefore, according to this embodiment, even if the excitation power supply voltage fluctuates, it is possible to control the field current IF according to the AVR control signal Vr, and it is possible to improve control accuracy.

〔Effect of the invention〕

As explained above, according to the present invention, the physical quantity of the field excitation system such as the field current that fluctuates depending on the excitation power supply voltage is detected, and the detected physical quantity is negatively fed back to correct the AVR control signal. Therefore, fluctuations in the field current caused by fluctuations in the excitation power supply voltage can be minimized, and A V
RIIJ control accuracy can be improved.

In addition, by adding elements suitable for suppressing power fluctuation to the transfer function of the negative feedback system described above, it is possible to suppress power fluctuation together with AVR, realizing a highly reliable and inexpensive excitation control device. can.

In addition, with a device that detects fluctuations in the excitation power supply voltage and corrects and controls the conduction angle of a switching element such as a thyristor of the excitation device according to the detected value, it is possible to detect fluctuations in the excitation power supply voltage with a simple structure. Therefore, fluctuations in the field current caused by this can be made minute, and AVR control accuracy can be improved.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the overall structure of an excitation device according to an embodiment of the present invention, Fig. 2 is a block diagram of a modified example of the embodiment shown in Fig. 1, and Fig. 3 is an overall diagram of another embodiment of the present invention. This is a schematic diagram. ■... Armature, 2... Field winding, 4... Excitation device body, 5... Excitation transformer, 6... Voltage transformer, 7... Current detector, 10... Automatic voltage regulator (AVR) L1...AV
R calculation unit, 12... Gate pulse generation unit, l3... Field current feedback calculation unit.

Claims (1)

[Claims] 1. A generator excitation method comprising detecting a deviation between the output voltage of the generator and a reference voltage, and controlling the generator's field so that the deviation becomes zero. A method for exciting a generator, characterized by detecting a field current of the machine or an amount of electricity corresponding to the field current, and correcting a field control amount by negative feedback of the detected value. 2. The generator excitation method according to claim 1, wherein the correction of the field control amount is determined to be a correction amount that suppresses fluctuations in the excitation power supply voltage. 3. The generator excitation method according to claim 1, wherein the correction of the field control amount is determined to be a correction amount that suppresses fluctuations in the excitation power supply voltage and fluctuations in the power system. 4. In a generator excitation device comprising automatic voltage adjustment means that determines the field control amount of the generator in order to excite the output voltage of the generator to the reference voltage, the generator field current or equivalent thereof is used. a field current detection means for detecting an amount of electricity;
An excitation device for a generator, comprising field current feedback correction means for correcting the field control amount by negative feedback of the detected amount. 5. The field current feedback correction means has a transfer function that includes at least one of an element for suppressing fluctuations in the power supply voltage of the excitation device and an element for suppressing fluctuations in the electric power system. generator exciter. 6. An excitation device body and an automatic voltage adjustment device, the automatic voltage adjustment device inputting the output voltage of the generator, and controlling the field control amount according to the deviation so that the output voltage matches the reference voltage. In the excitation device for a generator, the excitation device main body inputs the field control amount and supplies a field current to the generator according to the field control amount. It has a field current detection means for detecting a current or an amount of electricity equivalent thereto, the excitation device main body is a power conversion device formed from a switching element such as a thyristor, and the automatic voltage adjustment means has an automatic voltage adjustment means. It has an adjustment calculation section, a gate pulse generation section, and a field current feedback calculation section, and the automatic voltage adjustment calculation section inputs a deviation between the output voltage of the generator and a reference voltage, and makes this deviation zero. The field current feedback calculation unit inputs the detection value of the field current detection means and determines the correction amount of the field control amount based on this detection value. The gate pulse generator inputs a field control amount obtained by subtracting the correction amount from the field control amount, and controls the firing angle of the switching element of the exciter main body based on the corrected control amount. An excitation device for a generator that generates pulses. 7. To match the output voltage of the generator with the reference voltage,
In a method for excitation of a generator, which includes controlling the field of the generator in accordance with the deviation, the amount of variation in the excitation power supply voltage that supplies the field power is detected, and the amount of variation in the excitation power source voltage that supplies the field power is detected, and the amount of variation is adjusted to A generator excitation method characterized by correcting a field control amount. 8. An excitation device body and an automatic voltage adjustment device, the automatic voltage adjustment device inputting the output voltage of the generator, and controlling the field control amount according to the deviation so that the output voltage matches the reference voltage. In the excitation device for a generator, the excitation device main body inputs the field control amount and supplies a field current to the generator according to the field control amount, wherein the excitation device main body 1. An excitation device for a generator, comprising means for detecting fluctuations in power supply voltage and correcting the field control amount so as to reduce fluctuations in field current due to fluctuations in power supply voltage. 9. The excitation device main body is a power conversion device consisting of a switching element such as a thyristor, and the field control amount determined by the automatic voltage regulator is:
the ignition control signal for the switching element, and the field control amount correction means corrects the ignition phase of the ignition control signal in accordance with fluctuations in the excitation power supply voltage. Item 8. Excitation device for a generator according to item 8. 10. A power generator using the generator excitation method or excitation device according to any one of claims 1 to 9.