JPH10285998A - Excitation controller for synchronous machine and ac electric-signal detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the quantity of electricity accurately even when the frequency of an AC signal is fluctuated. SOLUTION: An excitation controller and a voltage detector 1A for the synchronous motor has an amplitude arithmetic means 5, which converts the quantity of electricity detected into a digital signal for a fixed period and into which the converted quantity of electricity is inputted and which outputs the amplitude arithmetic result B of the value of a digital signal D on the basis of the digital signal, and an integral arthmetic means 6 adding the absolute value of the digital signal D by a fixed number and outputting an integral arithmetic result S, and the amplitude arithmetic result B and the integral arithmetic result S are changed and outputted according to the frequency detecting signal F of the AC voltage V0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC power supply such as an output voltage of a synchronous machine connected to an electric power system, which is accurately measured even if the frequency of the AC power varies, and used for control. The present invention relates to an electric signal detection device and an excitation control device for a synchronous machine.

[0002]

2. Description of the Related Art For example, an automatic voltage regulator (hereinafter referred to as AVR) for controlling an output voltage of a synchronous machine (generator) measures a sine wave AC voltage. In the measurement of the sine wave AC voltage, methods such as an amplitude calculation method for calculating the amplitude of the voltage, an integration calculation method for calculating the integral value, and a normalization calculation method for converting the analog signal into a DC signal and normalizing the signal are used. There is.

[0003] A conventional voltage detecting device using an amplitude calculation method will be described with reference to FIG. The voltage detection device 1 includes an AD conversion processing unit 2 and an arithmetic processing unit 3. The AC voltage V 0 is input to the AD conversion processing unit 2, and the output of the AD conversion processing unit 2 is converted into a digital signal matrix D by the arithmetic processing unit 3. And the output of the arithmetic processing unit 3 is output from the voltage detection device 1 as a voltage detection signal V1. Next, these will be described in detail.

First, in the AD conversion processing section 2, the AC voltage V
The instantaneous value of 0 is converted into a digital signal at a constant cycle, and a digital signal matrix D is output as a digital signal for each cycle. The arithmetic processing unit 3 has an amplitude calculating means 5,
From the digital signal matrix D, a voltage detection signal V1 proportional to the effective value or the average value of the AC voltage V0 is calculated and output.

[0005] The calculation method by the amplitude calculation means 5 is shown in FIG.
In the case of the AC voltage V0 as shown in FIG.
Is 1/12 times the cycle of the AC voltage V0, the calculation shown in equation (1) is performed.

[0006]

(Equation 1)

However, K: a constant for converting the amplitude value into an effective value or an average value B: the result of amplitude calculation Dn: the value of the digital signal matrix (n times before) SQRT: square root Here, the amplitude of the input voltage is represented by A. Then, equation (1) is represented as equation (2).

[0008]

(Equation 2)

Further, when the right side of equation (2) is solved using a trigonometric function, it is expressed as equation (3). B = K * A (3) According to the equation (3), it is understood that the amplitude calculation result B is proportional to the amplitude value A of the AC voltage V0 and that there is no calculation error.

FIG. 22 is an explanatory diagram showing frequency characteristics of the amplitude subtraction method, and shows a reference frequency F satisfying the condition of equation (2).
When the frequency of the AC voltage V0 changes to 0, the voltage detection signal V1 based on the amplitude calculation result B changes as illustrated. This method has a characteristic that the calculation error is small at the reference frequency F0 and that the voltage detection signal V1 based on the amplitude calculation output B decreases when the frequency fluctuates.

Next, a description will be given of a conventional voltage detecting device using an integral operation method with reference to FIG. The voltage detection device based on the integral operation method shown in FIG.
Is an integral operation means 6, and the effective value of the AC voltage V0 or the effective value of the AC voltage V0 A voltage detection signal V1 proportional to the average value is calculated and output. The integration operation means 6 performs the operation shown in Expression (4).

[0012]

(Equation 3)

Here, L: a constant for converting the integrated value into an effective value or an average value S: the result of the integration operation Dn: the value of the digital signal matrix (n times before) FIG. 24 is a frequency characteristic diagram of the integration operation method. . In this calculation method, as the value of the sampling number N with respect to the period of the AC signal increases (when the sampling period is constant, the frequency of the AC voltage V0 decreases), the calculation accuracy improves.

For example, if the integration of a half cycle is performed when the conversion cycle of the A / D conversion processing unit 2 is 1/12 times the cycle of the AC voltage V0, the sampling number N is six. In this case, the calculation error (ripple width in the figure) is about 1.7%. When the frequency fluctuates with respect to the reference frequency F0 of the AC voltage V0, there is a characteristic that the sampling number N increases in a low frequency region and the accuracy is relatively improved on the assumption that the integration is performed in a half cycle.

Next, a conventional voltage detecting device using a normalization operation method will be described with reference to FIG. In the figure, a voltage detection device 1 includes a rectification processing unit 9 that converts an AC voltage V0 into a DC voltage V2, a filter 10 that smoothes the DC voltage V2, and a digital signal that converts the smoothed DC voltage V3 at a constant period. An AD conversion processing unit 11 that converts and outputs a digital signal matrix D1 and an arithmetic processing unit 3 that calculates and outputs a voltage detection signal V1 proportional to the effective value or average value of the AC voltage V0 from the digital signal matrix D1. The arithmetic processing unit 3 comprises a normalizing operation means 12 for converting the digital signal matrix D1 into a signal proportional to the effective value or the average value. The normalization operation means 12 performs an operation as shown in Expression (5).

[0016]

(Equation 4)

Here, M: a constant for converting the value of the DC voltage into an effective value or an average value G: the result of the normalization operation Dn: the value of the digital signal matrix (n times before) In this operation method, the AC voltage V0 is Although the AD conversion process is performed after rectification and smoothing, the rectified waveform of the AC voltage V0 includes ripples, and ripples that cannot be removed by the filter 10 appear as ripples in the output.

FIG. 26 is a frequency characteristic diagram of the normalization operation method. In this operation method, when the frequency of the input voltage V0 is higher than the reference frequency F0, the effect of the filter 10 is increased and the ripple is reduced. There is a characteristic that accuracy is relatively improved.

Here, comparing the amplitude calculation method, the integration calculation method, and the normalization calculation method, the amplitude calculation method has the highest calculation accuracy near the reference frequency F0. Although the accuracy of the integral operation method differs depending on the number of samplings N, the operation accuracy is higher than the amplitude operation method except for the vicinity of the reference frequency F0. Although the accuracy of the normalization operation method differs depending on the performance of the filter, the operation accuracy is higher than that of the amplitude operation method except for the vicinity of the reference frequency F0. Also, comparing the integral operation method and the normalization operation method, when the error at the reference frequency F0 is the same, the accuracy of the integral operation method increases as the frequency decreases, and the accuracy of the normalization operation method increases as the frequency increases. As a result, the integration operation method is excellent at a low frequency, and the normalization operation method is excellent at a high frequency.

[0020]

However, in the measurement of the AC voltage using the amplitude calculation method, when the frequency is the reference frequency F0 of the AC voltage V0 as shown in FIG. Although it has a characteristic of being small, there is a drawback that the voltage detection signal V1 based on the amplitude calculation result B decreases due to the fluctuation of the frequency. For example,
When the frequency of the AC voltage V0 becomes 1.5 times the reference frequency F0, the amplitude calculation result B obtained by the amplitude calculation means 5 becomes 50%. This is, as shown in equation (1), every 90 degrees of the fundamental wave (data D before sampling 3).
-3), which is a method of calculating based on the data. If the frequency of the signal to be detected fluctuates, it deviates from 90 degrees, so that a large error occurs.

In addition, in the integral operation method, when the frequency of the AC voltage V0 changes, if the frequency is low, the sampling number N increases and the accuracy is improved. However, an error caused by the operation method always occurs. There was a drawback of doing. This is a method of adding and averaging voltage values for a certain period of time as shown in Expression (4). However, if the frequency fluctuates, the integration range for a sine wave changes, and stable detection cannot be performed. If a large integration range is set, the stability is improved, but on the contrary, the response is deteriorated.

In the normalization operation method, the input voltage V0
When the frequency is higher, the effect of the filter 10 is increased and the ripple is reduced. Therefore, although the voltage detection accuracy is improved, there is a defect that an error always occurs due to the ripple of the input voltage V0. In addition, there are analog circuits such as the rectification processing unit 9 and the filter 10, and the accuracy cannot be increased due to the influence of temperature drift and harmonics.

As described above, when an error occurs in the voltage detection, an error occurs in the control amount even in the excitation control device of the synchronous machine having the automatic voltage regulator that measures the voltage and calculates the control amount. Generates an erroneous output voltage and adversely affects the power system.

In particular, the output voltage of a synchronous machine or the like may be operated and controlled in a region far from the fundamental frequency of the system during the start and stop processes of the synchronous machine. It may fluctuate, and it is necessary to take countermeasures for the influence when the frequency of the AC electricity quantity fluctuates.

Accordingly, the present invention provides a method of detecting an AC electric quantity, which accurately detects an effective value or an average value of an electric quantity (voltage, current, etc.) even when the frequency of the AC electric quantity fluctuates, and uses the same for control. It is an object of the present invention to provide a voltage detection device and an excitation control device for a synchronous machine that can perform the control.

[0026]

[Means for Solving the Problems]

(1) An excitation control device for a synchronous machine according to the present invention is configured to control an output voltage of a synchronous machine connected to an AC power system by adjusting an excitation device that excites an excitation circuit of the synchronous machine. A / D conversion processing means for inputting the output voltage of the synchronous machine and converting the instantaneous value of the input electric quantity into a digital signal at a predetermined cycle, and a plurality of digital signals having different frequency characteristics using the digital signal output from the A / D conversion processing means. A plurality of calculating means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the output voltage of the synchronous machine according to the arithmetic method, and a frequency detecting means for detecting a frequency of an output AC electric quantity of the synchronous machine, Depending on the frequency detected by the frequency detecting means, the output of any one of the plurality of calculating means and an electrical quantity detection signal corresponding to the effective value or average value of the output voltage of the synchronous machine Output means, and an automatic voltage adjusting means for performing an excitation control operation based on the electric quantity detection signal output from the output means and adjusting the output of the excitation control signal to the excitation device. It is.

(2) In the above (1), the plurality of calculation means use the digital signal output from the AD conversion processing means and calculate the amplitude of the AC electric quantity according to the amplitude calculation method of the synchronous machine. A basic operation means for calculating an electric quantity detection signal corresponding to an effective value or an average value of an output voltage; and an integral operation method or an AC electric method for integrating an AC electric quantity using a digital signal output from the AD conversion processing means. It comprises a preliminary calculation means for calculating an electric quantity detection signal corresponding to the effective value or the average value of the output voltage of the synchronous machine according to at least one of the normalization calculation methods for normalizing the quantity.

(3) Further, in the above (2), when the frequency detected by the frequency detecting means is within a predetermined range including a basic frequency of the amount of AC electricity in the electric power system, the output means outputs the signal from the basic calculating means. Output means for outputting an electric quantity detection signal and outputting an electric quantity detection signal from the preliminary calculation means when the frequency detected by the frequency detection means is outside the predetermined range.

(4) The excitation control device for a synchronous machine according to the present invention controls the output voltage of the synchronous machine connected to the AC power system by adjusting the excitation device for exciting the excitation circuit of the synchronous machine. Using an A / D conversion processing means for inputting an output voltage of the synchronous machine, converting an instantaneous value of the input electric quantity into a digital signal at a predetermined cycle, and a digital signal output from the A / D conversion processing means; Basic operation means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the output voltage of the synchronous machine in accordance with an amplitude calculation method for calculating the amplitude of an AC electric quantity; and a digital signal output from the AD conversion processing means. And the synchronous machine according to at least one of an integration operation method for integrating the AC electric quantity and a normalization operation method for normalizing the AC electric quantity. A preliminary calculation means for calculating an electric quantity detection signal corresponding to the effective value or the average value of the output voltage,
Output means having high value priority means for selecting and outputting a high value signal of each electric quantity detection signal output by the basic operation means and preliminary operation means; and exciting control based on the electric quantity detection signal output by the output means. Automatic voltage adjusting means for performing calculations and adjusting the output of the excitation control signal to the excitation device.

(5) Next, the AC electric signal detection device of the present invention is provided with an AD conversion processing means for inputting an AC electric quantity and converting an instantaneous value of the input electric quantity into a digital signal at a predetermined cycle, and the AD conversion processing means. A plurality of arithmetic means for calculating an electrical quantity detection signal corresponding to an effective value or an average value of the AC electrical quantity according to a plurality of different arithmetic schemes using a digital signal output from the conversion processing means; and a frequency of the AC electrical quantity. And an output of any one of the plurality of arithmetic means is output as an electric quantity detection signal corresponding to an effective value or an average value of the AC electric quantity according to the frequency detected by the frequency detecting means. Output means for performing the operation.

(6) In the above (5), the plurality of calculation means use the digital signal output from the AD conversion processing means and calculate the amplitude of the AC electricity in accordance with the amplitude operation method. A basic operation means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the AC electric quantity, and the AC electric quantity according to an integral operation method for integrating and calculating the AC electric quantity using a digital signal outputted from the AD conversion processing means. And preliminary calculation means for calculating an electric quantity detection signal corresponding to the effective value or the average value of

(7) And in the above (5),
The plurality of arithmetic means uses a digital signal output from the AD conversion processing means to calculate an electrical quantity detection signal corresponding to an effective value or an average value of the AC electrical quantity according to an amplitude arithmetic method for calculating the amplitude of the AC electrical quantity. Using a basic operation means for calculating and a digital signal output from the AD conversion processing means, detecting an electric quantity corresponding to an effective value or an average value of the AC electric quantity according to a normalization operation method for normalizing the AC electric quantity. It consists of preliminary operation means for operating the signal. (8) In the above (7), the preliminary calculation means uses the digital signal output from the second AD conversion processing means for converting the DC electric quantity obtained by rectifying the input electric quantity into a digital signal, and It is a calculating means for calculating the amount detection signal.

(9) And in the above (5),
The plurality of arithmetic means uses a digital signal output from the AD conversion processing means to calculate an electrical quantity detection signal corresponding to an effective value or an average value of the AC electrical quantity according to an amplitude arithmetic method for calculating the amplitude of the AC electrical quantity. A basic operation unit for performing an operation and a digital signal output from the AD conversion processing unit, and an electric amount detection signal corresponding to an effective value or an average value of the AC electric amount is calculated according to an integral operation method for performing an integral operation on the AC electric amount. The first preliminary calculation means for calculating and the digital signal output from the A / D conversion processing means correspond to an effective value or an average value of the AC electric quantity according to a normalization operation method for normalizing the AC electric quantity. It comprises second preliminary calculation means for calculating the electric quantity detection signal.

(10) Further, in the above (6), (7) and (9), the output means may output the signal when the frequency detected by the frequency detection means is within a predetermined range including a predetermined fundamental frequency of the AC electric quantity. Output means for outputting an electric quantity detection signal from a basic operation means and outputting an electric quantity detection signal from the preliminary operation means when the frequency detected by the frequency detection means is outside the predetermined range.

(11) Further, the above (6) and (7)
(9) In (10), the output unit includes a switching selection unit that selectively switches or weights and outputs each of the electric quantity detection signals output by the plurality of calculation units, and outputs the switching.
(12) The switching selection means of the output means is a switching selection means having a predetermined hysteresis width at a switching boundary.

(13) Further, the AC electric signal detection device of the present invention is provided with an AD conversion processing means for inputting an AC electric quantity and converting an instantaneous value of the input electric quantity into a digital signal at a predetermined cycle, A plurality of arithmetic means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the AC electric quantity according to a plurality of different arithmetic schemes using a digital signal output from the processing means; Output means having high value priority means for selecting a high value signal of each of the electric quantity detection signals to be output and outputting the selected signal as an electric quantity detection signal corresponding to an effective value or an average value of the AC electric quantity.

(14) In the above (13),
The plurality of arithmetic means uses a digital signal output from the A / D conversion processing means and detects an electric quantity corresponding to an effective value or an average value of the output voltage of the synchronous machine in accordance with an amplitude operation method for calculating an amplitude of an AC electric quantity. At least one of a basic operation unit for calculating a signal, an integration operation method for integrating an AC electric amount using a digital signal output from the AD conversion processing unit, and a normalization operation system for normalizing the AC electric amount It comprises a preliminary calculation means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the output voltage of the synchronous machine according to one of the calculation methods.

[0038]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an excitation control device for a synchronous machine according to a first embodiment of the present invention.

In FIG. 1, the output voltage and output current of synchronous machine 20 connected to the AC power system are
21 and an electric current (AC voltage V0, AC current I0) via the current transformer CT22. The excitation control device 23 includes the AC electric signal detection device 1
X and an automatic voltage adjustment operation means 24 for performing an excitation adjustment operation, and using an excitation control signal E as a control amount thereof, the excitation device 2
5 to excite the excitation circuit of the synchronous machine.

The AC electric signal detection device 1X calculates an electric quantity corresponding to an effective value or an average value of the AC electric signals V0 and / or I0, and outputs an electric quantity detection signal V1 and / or I1. And automatic voltage adjustment calculating means 2
4 performs an adjustment operation (for example, obtains a control amount such that a deviation between a voltage set value and a detected value becomes zero) from these signals, and
The excitation control signal E is output to the excitation device 25.

FIG. 2 is a block diagram showing a first embodiment of the AC electric signal detecting device (voltage detecting device) of the present invention. 2, a voltage detection device 1A includes an AD conversion processing unit 2 and an arithmetic processing unit 3A. The AC voltage V0 is input to the AD conversion processing unit 2, and the output of the AD conversion processing unit 2 is calculated as a digital signal matrix D. It is configured to be input to the processing unit 3 and to output the output of the arithmetic processing unit 3A as the voltage detection signal V1.

The AD conversion processing unit 2 converts the instantaneous value of the AC voltage V0 into a digital signal at a constant cycle and outputs a digital signal matrix D. The arithmetic processing unit 3A is a device that calculates and outputs a voltage detection signal V1 proportional to the effective value or average value of the AC voltage V0 from the digital signal matrix D, and is proportional to the frequency of the AC voltage V0 based on the digital signal matrix D. Frequency detection means 4 for outputting a frequency detection signal F;
Amplitude calculation means 5 (basic calculation means) for outputting an amplitude calculation result B of the value of the digital signal matrix D, and integration calculation means 6 for adding an absolute value of the digital signal matrix D a predetermined number of times and outputting an integration calculation result S (Preliminary calculation means), function generation means 7 for outputting a switching signal Q for amplitude calculation result B and integration calculation result S based on frequency detection signal F, and amplitude calculation result B and integration calculation result S based on switching signal Q And switching means 8 for switching.

FIG. 3 is a frequency characteristic diagram of the voltage detecting device 1A showing the operation of the first embodiment of the present invention. In the figure, in the frequency range where the frequency detection signal F is from the lower limit switching frequency F1 to the upper limit switching frequency F2 around the reference frequency F0, the amplitude calculation result B
Is output, and the value of the amplitude calculation result B is output by the switching means 8 as the voltage detection signal V1.

On the other hand, if the frequency detection signal F is lower than the lower limit frequency F1
At a frequency lower than or equal to or higher than the upper limit switching frequency F2, the switching signal Q is output from the function generating means 7 so as to select the integration calculation result S, and the value of the integration calculation result S is output as the voltage detection signal V1 by the switching means 8. Is done.

According to this configuration, the amplitude calculation means 5 outputs the amplitude calculation result B in a frequency region with high accuracy, and in the frequency region in which the accuracy decreases, outputs the integration calculation result S as the voltage detection signal V
It can be output as 1. Therefore, the AC voltage V0
Even if the frequency f1 fluctuates with respect to the reference frequency F0, the calculation means can be switched so that accurate voltage detection is possible.

As described above, according to the first embodiment, even when the rotation speed of the synchronous machine changes and the frequency of the output electric quantity changes from the reference frequency F0, the voltage can be detected with high accuracy. Since the signal V1 is obtained, the output of the automatic voltage adjustment calculation means is also accurate, and it is possible to obtain a synchronous machine excitation control device capable of performing accurate control.

The present invention has the same configuration as that of the first embodiment. In the function generator 7 as shown in FIG. 4, the switching signal Q is used in the function generator 7 based on the frequency detection signal F obtained by the frequency detector 4. Hysteresis characteristics can also be provided.

That is, the lower limit switching frequencies F3 and F4 and the upper limit switching frequencies F5 and F6 of the frequency detection signal F centered on the reference frequency F0 are set in advance. Here, the lower limit switching frequency F3 is a frequency at which the amplitude calculation result B is switched to the integration calculation result S, and the lower limit switching frequency F4 is a frequency at which the integration calculation result S is switched to the amplitude calculation result B. The upper limit switching frequency F5 is a frequency at which the integration operation result S is switched to the amplitude operation result B, and the upper limit switching frequency F6 is a frequency at which the amplitude operation result B is switched to the integration operation result S.

Since there is a hysteresis characteristic between the lower limit switching frequencies F3 and F4 and between the upper limit switching frequencies F5 and F6, there is no change in the switching signal Q of the function generating means 7 when the frequency detection signal F changes within this range. .

According to this configuration, in addition to the operation of the first embodiment of the present invention, even if the frequency detection signal F is in the vicinity of the switching frequency and within the range of the hysteresis characteristic, there is no change in the switching signal Q. Therefore, there is an effect that switching between the amplitude calculation result B and the integration calculation result S does not occur, and the frequent fluctuation of the calculation output V1 due to the difference in the calculation means can be suppressed.

FIG. 5 is a block diagram showing a second embodiment of the voltage detecting device according to the present invention. 5, the voltage detection device 1B is different from the embodiment of FIG. 2 in the output unit. The same components are denoted by the same reference numerals, description thereof will be omitted, and differences will be described.

The arithmetic processing unit 3B outputs a weighted signal R for the amplitude calculation result B and the integration calculation result S based on the frequency detection signal F, and an amplitude calculation result B based on each weighted signal R. And a calculating means 13 for multiplying the integration calculation result S by the weighting signal R, adding the values, and outputting the voltage detection signal V1.

FIG. 6 is a frequency characteristic diagram of the voltage detecting device showing the operation of the second embodiment of the present invention. In the figure,
Lower limit weighting frequencies F7 and F8 and upper limit weighting frequencies F9 and F10 are set in advance around the reference frequency F0 according to the frequency detection signal F. Here, in the range of the lower limit weighting frequencies F7 to F8, when the frequency detection signal F increases, the weight of the amplitude calculation result B increases and the integration calculation result S
Weighting signal R changes so as to reduce the weight of.

The upper limit weighting frequencies F9 to F10
When the frequency detection signal F increases, the weighting signal R changes so that the weight of the amplitude calculation result B decreases and the weight of the integration calculation result S increases.

According to this configuration, the amplitude calculation result B and the integration calculation result S are weighted according to the frequency of the AC voltage V0, and the voltage detection signal V1 can be obtained by adding the weights. Thus, if a function is generated in advance so as to increase the weight for the arithmetic means having a small error, an accurate arithmetic result can be obtained even when the frequency of the AC voltage V0 fluctuates. In addition, since weighting is performed, discontinuous fluctuations in the output due to differences in the calculation means are small.

FIG. 7 is a block diagram showing a third embodiment of the voltage detecting device according to the present invention. This embodiment is different from the embodiment of FIG. 2 in that an integral operation method is used as the preliminary operation means, whereas a normalization operation means is used as the preliminary operation means.

In FIG. 7, a voltage detecting device 1C converts an instantaneous value of the AC voltage V0 into a digital signal at a constant cycle and outputs a digital signal matrix D.
A rectification processing unit 9 for converting the AC voltage V0 to a DC voltage V2, a filter 10 for smoothing the DC voltage V2,
It is composed of an AD conversion processing unit 11 that converts the smoothed DC voltage V3 into a digital signal at a constant cycle and outputs a digital signal matrix D1, and an arithmetic processing unit 3C.

Then, the arithmetic processing unit 3C outputs the AC voltage V0
Frequency detecting means 4 for outputting a frequency detection signal F proportional to the frequency of the AC voltage V0 based on the digital signal matrix D obtained from the instantaneous values of the above, and amplitude calculating means 5 for outputting the amplitude calculation result B of the digital signal matrix D (Basic calculation means) and normalization calculation means 12 (preliminary calculation means) for converting the digital signal matrix D1 obtained from the smoothed DC voltage into a signal proportional to the effective value or the average value.

As output means, a function generating means 7 for outputting a switching signal Q for the amplitude calculation result B and the normalization calculation result G in accordance with the frequency detection signal F; And switching means 8 for switching the conversion operation result G.

FIG. 8 is a frequency characteristic diagram of the voltage detecting device showing the operation of the third embodiment of the present invention. As shown in the figure, the switching signal Q for selecting the amplitude calculation result B is output from the function generating means 7 at the frequencies from the lower limit switching frequency F11 to the upper limit switching frequency F12 around the reference frequency F0 according to the frequency detection signal F. Then, the value of the amplitude calculation result B is output as the voltage detection signal V1 by the switching means 8.

On the other hand, when the frequency detection signal F is lower than the lower limit switching frequency F11 or higher than the upper limit switching frequency F12, the function generating means 7 outputs a switching signal Q for selecting the normalization operation result G, and the switching means 8 The value of the conversion operation result G is output as the voltage detection signal V1.

According to this configuration, while the amplitude calculation result B is selected in the frequency region with high accuracy by the amplitude calculation means 5,
The normalized calculation result G is selected in a frequency region where the calculation accuracy is reduced, and can be output as the voltage detection signal V1. Therefore, even if the frequency of the AC voltage V0 fluctuates, accurate voltage detection can be performed by switching the calculation means.

The present invention has the same configuration as that of the third embodiment. In the function generator 7 as shown in FIG. 9, a hysteresis is applied to the switching signal Q based on the frequency detection signal F obtained by the frequency detector 4. Can have characteristics.

That is, the lower limit switching frequency F13 is a frequency for switching from the amplitude calculation result B to the normalization calculation result G, and the lower limit switching frequency F14 is a frequency for switching from the normalization calculation result G to the amplitude calculation result B.

The upper limit switching frequency F15 is a frequency at which the normalization calculation result G is switched to the amplitude calculation result B, and the upper limit switching frequency F16 is a frequency at which the amplitude calculation result B is switched to the normalization calculation result G. Since there is a hysteresis characteristic between the lower limit switching frequencies F13 and F14 and between the upper limit switching frequencies F15 and F16, a change in the frequency detection signal F within this range does not cause a change in the switching signal Q of the function generator 7;
Excessive switching due to frequency fluctuation near the boundary can be prevented, and frequent fluctuation of the calculation output V1 can be suppressed.

FIG. 10 is a block diagram showing a fourth embodiment of the voltage detecting device according to the present invention. 10, the voltage detector 1D differs from the embodiment of FIG. 7 in the output unit. The same components are denoted by the same reference numerals, description thereof will be omitted, and differences will be described.

The arithmetic processing unit 3D outputs a weighting signal R for the amplitude calculation result B and the normalization calculation result G based on the frequency detection signal F, and outputs the amplitude calculation result B based on the weighting signal R. And a calculation means 13 for multiplying the normalization calculation result G by the weighting signal R, adding those values, and outputting the voltage detection signal V1.

According to this configuration, it is possible to obtain a calculation output by weighting the amplitude calculation result B and the normalization calculation result G according to the frequency of the AC voltage V0. Thus, if a function is generated in advance so as to increase the weight for the arithmetic means having a small error, an accurate arithmetic result can be obtained even when the frequency of the AC voltage V0 fluctuates.

Further, since the weighting is performed, there is no discontinuous fluctuation of the output due to the difference of the calculation means, so that a stable calculation result can be obtained. FIG. 11 is a frequency characteristic diagram of the voltage detection device showing the operation of the fourth embodiment of the present invention.

In the figure, lower limit weighting frequencies F17 and F18 and upper limit weighting frequencies F19 and F20 centering on the reference frequency F0 are set in advance. Here, in the range of the lower limit weighting frequencies F17 to F18, when the frequency increases, the weighting signal R changes so that the weight of the amplitude calculation result B increases and the weight of the normalization calculation result G decreases.

Further, the upper limit weighting frequencies F19 to F2
In the range of 0, when the frequency increases, the weight of the amplitude calculation result B decreases, and the weighting signal R changes so as to increase the weight of the normalization calculation result G.

As a result, since there is no discontinuous change in the output due to the difference in the calculation means, a stable calculation result can be obtained. FIG. 12 is a configuration diagram showing a fifth embodiment of the voltage detection device of the present invention. This embodiment is different from the embodiment of FIGS. 2, 5, 7, and 10 in that an output unit having a high value priority unit is used.

In FIG. 12, a voltage detecting device 1E converts an instantaneous value of the AC voltage V0 into a digital signal at a constant cycle and outputs a digital signal matrix D.
, A rectification processing unit 9 for converting the AC voltage V0 into a DC voltage V2, a filter 10 for smoothing the DC voltage V2, and an arithmetic processing unit 3E.

The arithmetic processing section 3E includes an amplitude calculating means 5 for outputting an amplitude calculation result B of the digital signal matrix D, and a digital signal matrix D1 obtained from the smoothed DC voltage V3.
Is calculated into a signal proportional to the effective value or the average value, and a normalization operation means 12 that outputs a normalization operation result G, compares the amplitude operation result B with the normalization operation result G, and selects a larger value. And high value priority means 14 for outputting the data.

According to this configuration, it is possible to obtain, as a calculation output, a larger one of the calculation results of the amplitude calculation result B and the normalization calculation result G. The amplitude calculating means 5 has the highest accuracy near the reference frequency F0 according to the equation (2), and the output decreases as the accuracy fluctuates from the reference frequency. Can be selected in the frequency range where the calculation is possible, and the normalization calculation result can be selected in the other range.
In addition, there is also an operation and effect that the high value priority means 14 reduces the discontinuous fluctuation due to the difference in the calculation means at the switching point.

FIG. 13 is a block diagram showing the operation of the sixth embodiment of the voltage detector according to the present invention. The voltage detection device 1F shown in FIG. 13 is different from the configuration in FIG. 12 in that the output of each arithmetic unit is weighted according to the detected frequency.

The arithmetic processing section 3F outputs a weighting signal R for the amplitude calculation result B and the normalization calculation result G based on the frequency detection signal F, and outputs the amplitude calculation result B based on the weighting signal R. Calculating means 15 for multiplying the normalization calculation result G by the weighting signal R;
High-priority means 1 for comparing the amplitude calculation result B1 multiplied by .times. With the normalization calculation result G1 and selecting and outputting the larger value.
And 4.

FIG. 14 is a frequency characteristic diagram of the voltage detector showing the operation of the sixth embodiment of the present invention. As shown in the figure, lower limit weighting frequencies F21 to 24 and upper limit weighting frequencies F25 to 28 centered on the reference frequency F0 are set in advance. Here, lower limit weighted frequencies F21 to F
Reference numeral 22 denotes a frequency region in which the weight of the amplitude calculation result B increases as the frequency increases. Reference numerals F23 to F24 denote frequency regions in which the weight of the normalization calculation result G decreases as the frequency increases.

Further, the upper limit weighting frequencies F25 to F2
Reference numeral 6 denotes a frequency region in which the weight of the normalization operation result G increases as the frequency increases, and upper limit weighting frequencies F27 to F28 denote the frequency region in which the weight of the amplitude operation result B decreases as the frequency increases.

According to this configuration, lower limit weighting frequency F
In the frequency range from 21 to the upper limit weighting frequency F28, a large value of the weighted calculation result of the amplitude calculation result B and the normalization calculation result G can be obtained as a calculation output.

The amplitude calculating means 5 has the highest accuracy near the reference frequency F0 shown in the equation (2), and the output decreases as the frequency fluctuates and the accuracy becomes worse. 5, the amplitude calculation result is selected in the frequency region where the most accurate calculation is possible, and the normalization calculation result is selected in the other range.

Furthermore, the high value priority means 14 reduces the discontinuous output fluctuation due to the difference in the calculation means at the switching point.
In the configuration of FIGS. 12 and 13, the embodiment using the amplitude calculation means 5 as the basic calculation means and the normalization calculation means 12 as the preliminary calculation means has been described. However, as shown in FIG. The integration operation means 6 may be used. Further, a configuration using both the integral operation means 6 and the normalization operation means 12 as the preliminary operation means may be adopted.

FIG. 15 is a block diagram showing a seventh embodiment of the voltage detecting device according to the present invention. The voltage detection device 1G shown in FIG. 15 is a combination of the configuration shown in FIG. 2 and the configuration shown in FIG. In other words, the amplitude calculation means 5 is used as the basic calculation means, the normalization calculation means 12 and the normalization calculation means 12 are used as the preliminary calculation means, and the switching means is used as the output means, thereby improving the accuracy.

The arithmetic processing unit 3G comprises: a frequency detection means 4 for outputting a frequency detection signal F proportional to the frequency of the AC voltage V0 based on the digital signal matrix D obtained from the instantaneous value of the AC voltage V0; The amplitude calculation means 5 outputs the amplitude calculation result B, the integration calculation means 6 adds the absolute value of the digital signal matrix D a predetermined number of times, and outputs the integration calculation result S, and the smoothed DC voltage V3. Normalization means 12 for converting the digital signal matrix D1 into a signal proportional to the effective value or average value, and switching between an amplitude calculation result B, an integration calculation result S, and a normalization calculation result G according to the frequency detection signal F. It comprises a function generating means 7 for outputting a signal, and a switching means 8 for switching between an amplitude calculation result B, an integration calculation result S, and a normalization calculation result G based on the switching signal Q.

FIG. 16 is a frequency characteristic diagram of the voltage detector showing the operation of the seventh embodiment of the present invention. This frequency characteristic diagram shows that, at frequencies from the lower limit switching frequency F29 to the upper limit switching frequency F30 around the reference frequency F0, the switching signal Q for selecting the amplitude calculation result B from the function generator 7 according to the frequency detection signal F. Is output by the switching means 8, and the value of the amplitude calculation result B is output as the voltage detection signal V1.

The frequency detection signal F is lower than the lower limit frequency F2.
At a frequency lower than 9, a switching signal Q for selecting the integration operation result S is output from the function generating means 7, and the switching means 8
Outputs the value of the integration operation result S as the voltage detection signal V1.

When the frequency detection signal F is equal to the upper limit frequency F3
At a frequency exceeding 0, a switching signal Q for selecting the normalization operation result G is output from the function generation means 7, and the value of the normalization operation result G is output as a voltage detection signal V 1 by the switching means 8.

According to this configuration, the amplitude calculation result B is output as the voltage detection signal V1 in the vicinity of the reference frequency F0 where the accuracy of the amplitude calculation result B is good. The integration operation result S having relatively high accuracy is output as the voltage detection signal V1. Further, the upper limit frequency F30 at which the accuracy of the amplitude calculation result B decreases
In the higher frequency region, the normalization operation result G is output as the voltage detection signal V1.

As described above, according to the seventh embodiment, it is possible to obtain a calculation output by switching to any of the amplitude calculation result, the integration calculation result, and the normalization calculation result according to the frequency of the AC voltage V0. it can. Thus, if a function is generated in advance so as to select an operation means having a small error, an accurate operation result can be obtained even when the frequency of the AC voltage V0 fluctuates.

The present invention has the same configuration as that of the seventh embodiment. In the function generating means 7, as shown in FIG. 17, a hysteresis is applied to the switching signal Q based on the frequency detection signal F obtained by the frequency detection means 4. Can have characteristics.

That is, the lower limit switching frequencies F31 and F32 centered on the reference frequency F0 and the upper limit switching frequency F33
And F34 are set in advance. Here, the lower limit switching frequency F31 is a frequency for switching from the amplitude calculation result B to the integration calculation result S, and the lower limit switching frequency F32 is a frequency for switching from the integration calculation result S to the amplitude calculation result B.

The upper limit switching frequency F33 is a frequency at which the normalization calculation result G is switched to the amplitude calculation result B, and the upper limit switching frequency F34 is a frequency at which the amplitude calculation result B is switched to the normalization calculation result G. Here, since there is a hysteresis characteristic between the lower limit switching frequencies F31 and F32 and between the upper limit switching frequencies F33 and F34, the change of the switching signal Q of the function generating means 7 is small when the frequency detection signal F changes within this range. .

According to this configuration, in addition to the operation of the seventh embodiment of the present invention, even if the frequency detection signal F is in the vicinity of the switching frequency and within the range of the hysteresis characteristic, there is no change in the switching signal Q, so that the switching is not performed. Does not occur, and the frequent occurrence of fluctuations in the operation output V1 due to the difference in the operation means can be suppressed.

FIG. 18 is a block diagram showing an eighth embodiment of the voltage detecting device according to the present invention. In FIG. 18, the voltage detection device 1H is different from the output device of the configuration in FIG. 15 in that a weighting and adding unit is used instead of the switching unit.

The arithmetic processing unit 3H outputs a weighting signal to the amplitude calculation result B, the integration calculation result S, and the normalization calculation result G based on the frequency detection signal F.
Multiplying the amplitude calculation result B, the integration calculation result S, and the normalization calculation result G by the weighting signal based on the weighting signal R;
And a calculating means 13 for adding these values to output a voltage detection signal.

FIG. 19 is a frequency characteristic diagram of the voltage detector showing the operation of the eighth embodiment of the present invention. In this frequency characteristic diagram, lower limit weighting frequencies F35 and F36 and upper limit weighting frequencies F37 and F38 centering on the reference frequency F0 are set in advance. Here, the lower limit weighting frequencies F35 to F36 are frequency regions in which as the frequency increases, the weight of the amplitude calculation result B increases and the weight of the integration calculation result S decreases.

The upper limit weighting frequencies F37 to F3
8 decreases the weight of the amplitude calculation result B when the frequency increases,
This is a frequency domain in which the weight of the normalization calculation result G is increased. According to this configuration, the amplitude calculation result B is output as the voltage detection signal V1 in the vicinity of the reference frequency F0 where the accuracy of the amplitude calculation result B is good, and the accuracy is relatively low in the region where the frequency is lower than the lower limit frequency F35 where the accuracy decreases. A good integration operation result S is output as a voltage detection signal V1. Further, in a region where the frequency of the amplitude calculation result B is higher than the upper limit frequency F38 in which the accuracy is reduced, the normalized calculation result G is output as the voltage detection signal V1.

In the frequency range between the lower limit frequencies F35 and F36 and between the upper limit frequencies F37 and F38, the voltage detection signal V1 is output by weighting each calculation result. In the configuration of FIG. 18, the adding means of the output means may be high value priority means as in the configuration of FIG.

In the above description, equations (1), (4), and (5) are used as examples of the amplitude calculation method, the integration calculation method, and the normalization calculation method, respectively. For example, a formula that takes frequency error correction into account) may be used. In addition to voltage and current,
Active power and reactive power can also be detected. Also, a combination with another calculation method for calculating the effective value or the average value of the AC electricity amount may be used.

As described above, if the voltage detection devices of the first to eighth embodiments are the AC signal detection device of FIG. 1, an accurate amount of electricity can be obtained even if the frequency fluctuates, and It is possible to obtain an excitation control device for a synchronous machine that can perform good control.

[0101]

As described above, according to the present invention,
An AC electric quantity signal (voltage, etc.) is calculated using a plurality of arithmetic methods with different frequency characteristics, and a highly accurate calculation result is output as an electric quantity detection signal according to the frequency characteristic, so that the frequency of the detected electric quantity fluctuates. Thus, it is possible to obtain an AC electric signal detection device and an excitation control device for a synchronous machine, which can obtain an accurate electric quantity detection signal and can obtain an accurate control amount.

Further, the amplitude calculation method for calculating the amplitude of the AC electric quantity is used as the basic calculation method, and the integration calculation method or the normalization calculation method is used as the preliminary calculation method. In the frequency range away from the fundamental frequency, an output of the integration operation method or the normalization operation method is used, so that accurate and accurate electric quantity detection can be performed in a wide frequency band.

Further, by providing a plurality of preliminary operation methods and using the region having the best accuracy according to the frequency characteristics of each operation method, further effects can be expected. In addition, the output means multiplies the voltage detection signal of each operation method by the weighting signal in accordance with the frequency detection signal, and adds the obtained signals to form a voltage detection signal, so that the output from the operation means is switched. Therefore, it is possible to avoid the occurrence of the discontinuous fluctuation due to the difference in the output value of the calculation means.

Further, by using the high value priority means as the output means, it is possible to avoid the occurrence of discontinuous fluctuation due to the difference in the output value of the arithmetic means. In some cases, the frequency detecting means is not required.

Further, according to the present invention, since the switching of the output means is provided with hysteresis, frequent switching near the switching point is prevented, and the output fluctuates due to the difference between the voltage detection signals of the respective arithmetic means. A stable and accurate voltage detection signal is output.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an excitation control device for a synchronous machine according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a first embodiment of the voltage detection device of the present invention.

FIG. 3 is a frequency characteristic diagram of a function generating means provided in the voltage detection device of FIG. 2;

FIG. 4 is a frequency characteristic diagram of a function generator according to another embodiment of FIG. 2;

FIG. 5 is a configuration diagram showing a second embodiment of the voltage detection device of the present invention.

FIG. 6 is a frequency characteristic diagram of a function generator provided in the voltage detection device of FIG. 5;

FIG. 7 is a configuration diagram showing a third embodiment of the voltage detection device of the present invention.

8 is a frequency characteristic diagram of a function generating means provided in the voltage detection device of FIG.

FIG. 9 is a frequency characteristic diagram of the function generating means according to another embodiment of FIG. 7;

FIG. 10 is a configuration diagram showing a fourth embodiment of the voltage detection device of the present invention.

FIG. 11 is a frequency characteristic diagram of a function generator provided in the voltage detection device of FIG.

FIG. 12 is a configuration diagram showing a fifth embodiment of the voltage detection device of the present invention.

FIG. 13 is a configuration diagram showing a sixth embodiment of the voltage detection device of the present invention.

FIG. 14 is a frequency characteristic diagram of a function generating means provided in the voltage detection device of FIG.

FIG. 15 is a configuration diagram showing a seventh embodiment of the voltage detection device of the present invention.

FIG. 16 is a frequency characteristic diagram of a function generating means provided in the voltage detection device of FIG.

FIG. 17 is a frequency characteristic diagram of the function generating means according to another embodiment of FIG. 15;

FIG. 18 is a configuration diagram showing an eighth embodiment of the voltage detection device according to the present invention.

FIG. 19 is a frequency characteristic diagram of a function generating means provided in the voltage detection device of FIG. 18;

FIG. 20 is a configuration diagram of a voltage detection device using a conventional amplitude calculation method.

FIG. 21 is an explanatory diagram showing the amplitude calculation method of FIG.

FIG. 22 is a characteristic diagram showing the amplitude calculation method of FIG.

FIG. 23 is a configuration diagram of a voltage detection device according to a conventional integration operation method.

FIG. 24 is a characteristic diagram showing the integral operation method of FIG.

FIG. 25 is a configuration diagram of a voltage detection device using a conventional normalization operation method.

FIG. 26 is a characteristic diagram showing the normalization operation method of FIG.

[Explanation of symbols]

1A to 1H, 1X: voltage detection device, 2, 11: AD conversion processing unit, 3A to 3H: calculation processing unit, 4: frequency detection means, 5: amplitude calculation means, 6: integration calculation means, 7: function generation means .. 8 switching means, 9 rectification processing unit, 10 filter, 12 normalization calculation means, 13 calculation means, 14 high value priority means, 15 calculation means, 20 synchronous machine, 23 excitation control device, 24: Automatic voltage adjustment calculation means, V0: AC voltage, V1: Voltage detection signal, V2, V3: DC voltage,
D, D1 ... digital signal matrix, F ... frequency detection signal,
S: integration calculation result, Q: switching signal, B: amplitude calculation result,
G: Normalization calculation result, R: Weighted signal, F0: Reference frequency, F1, F3, F4, F11, F13, F14, F
29, F31, F32: Lower limit switching frequency, F2, F5
F6, F12, F15, F16, F30, F33, F3
4: Upper limit switching frequency, F7, F8, F17, F18, F
21 to F24, F35, F36 ... lower limit weighting frequencies,
F9, F10, F19, F20, F25 to F28, F3
7, F38: Upper limit weighting frequency

Claims (14)

[Claims] 1. An excitation control device for controlling an output voltage of a synchronous machine connected to an AC power system by adjusting an exciting device for exciting an exciting circuit of the synchronous machine. AD conversion processing means for converting the instantaneous value of the input electric quantity into a digital signal at a predetermined cycle; and A plurality of calculating means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the output voltage of the synchronous machine; a frequency detecting means for detecting a frequency of an output AC electric quantity of the synchronous machine; An output for outputting any one of the plurality of arithmetic means as an electric quantity detection signal corresponding to an effective value or an average value of an output voltage of the synchronous machine according to a frequency. Means, a synchronous machine, comprising: an excitation control operation based on an electric quantity detection signal output by the output means, and an automatic voltage adjustment means for adjusting an output of the excitation control signal to the excitation device. Excitation control device. 2. An excitation control device for a synchronous machine according to claim 1, wherein said plurality of calculating means calculates an amplitude of an AC electric quantity using a digital signal output from said AD conversion processing means. A basic operation means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the output voltage of the synchronous machine in accordance with: A preliminary calculation means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the output voltage of the synchronous machine according to at least one of an arithmetic method and a normalization operation method for normalizing an AC electric quantity. An excitation control device for a synchronous machine. 3. The excitation control device for a synchronous machine according to claim 2, wherein said output means is configured to output the signal when the frequency detected by the frequency detection means is within a predetermined range including a fundamental frequency of an AC electric quantity in the power system. Output means for outputting an electric quantity detection signal from a basic operation means, and outputting an electric quantity detection signal from the preliminary operation means when the frequency detected by the frequency detection means is outside the predetermined range. Excitation controller for synchronous machine. 4. An excitation control device for controlling an output voltage of a synchronous machine connected to an AC power system by adjusting an exciting device for exciting an exciting circuit of the synchronous machine, wherein the output voltage of the synchronous machine is inputted. AD conversion processing means for converting the instantaneous value of the input electric quantity into a digital signal at a predetermined cycle; and an amplitude calculation method for calculating the amplitude of the AC electric quantity using the digital signal output from the AD conversion processing means. A basic operation means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the output voltage of the synchronous machine; and an integral operation for integrating an AC electric quantity using a digital signal output from the AD conversion processing means. The effective value or the average value of the output voltage of the synchronous machine is calculated according to at least one of the normalization method and the normalization operation method for normalizing the AC electric quantity. Preliminary operation means for calculating the corresponding electric quantity detection signal; output means having high value priority means for selecting and outputting a high value signal of each electric quantity detection signal output by the basic operation means and the preliminary operation means; An excitation control device for a synchronous machine, comprising: an automatic voltage adjustment device that performs an excitation control operation based on an electric quantity detection signal output from an output device and adjusts an output of the excitation control signal to the excitation device. 5. An A / D conversion processing means for inputting an AC electric quantity and converting an instantaneous value of the input electric quantity into a digital signal at a predetermined cycle; and a plurality of digital signals output from the AD conversion processing means. A plurality of calculating means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the AC electric quantity according to different arithmetic methods; a frequency detecting means for detecting a frequency of the AC electric quantity; Output means for outputting an output of any one of the plurality of arithmetic means as an electric quantity detection signal corresponding to an effective value or an average value of the AC electric quantity according to the frequency obtained. Detection device. 6. The AC electric signal detecting device according to claim 5, wherein the plurality of calculating means uses a digital signal output from the AD conversion processing means and calculates an amplitude of the AC electric quantity according to an amplitude calculating method. A basic operation means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the AC electric quantity; and a digital signal output from the AD conversion processing means, and an integral operation method for integrating and calculating the AC electric quantity. An AC electric signal detection device, comprising: a preliminary operation means for calculating an electric amount detection signal corresponding to an effective value or an average value of the AC electric amount. 7. The AC electric signal detecting device according to claim 5, wherein said plurality of calculating means uses a digital signal output from said AD conversion processing means and calculates an amplitude of an AC electric quantity according to an amplitude calculating method. A basic operation means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the AC electric quantity; and a normalization operation for normalizing the AC electric quantity using a digital signal output from the AD conversion processing means. An AC electric signal detection device, comprising: a preliminary calculation means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the AC electric quantity according to a system. 8. The AC electric signal detection device according to claim 7, wherein the preliminary operation means is output from a second AD conversion processing means for converting the DC electric quantity obtained by rectifying the input electric quantity into a digital signal. An alternating-current electric signal detection device, which is a calculating means for calculating the electric quantity detection signal using a digital signal. 9. The AC electric signal detecting device according to claim 5, wherein the plurality of calculating means uses a digital signal output from the AD conversion processing means and calculates an amplitude of the AC electric quantity according to an amplitude calculating method. A basic operation means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the AC electric quantity; and a digital signal output from the AD conversion processing means, and an integral operation method for integrating and calculating the AC electric quantity. A first preliminary calculation unit for calculating an electric quantity detection signal corresponding to an effective value or an average value of the AC electric quantity; and a normalization operation of the AC electric quantity using a digital signal output from the AD conversion processing means. A second preliminary calculation means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the AC electric quantity according to a normalization operation method. Characteristic AC electric signal detection device. 10. The alternating-current electric signal detecting device according to claim 6, wherein the output means is arranged so that a frequency detected by the frequency detecting means is within a predetermined range including a predetermined fundamental frequency of the alternating-current electric quantity. Output means for outputting an electric quantity detection signal from the basic operation means, and outputting an electric quantity detection signal from the preliminary operation means when the frequency detected by the frequency detection means is outside the predetermined range. AC electric signal detecting device. 11. The alternating-current electric signal detecting device according to claim 6, wherein the output means selectively switches or weights and outputs each electric quantity detection signal output by the plurality of arithmetic means. An alternating-current electric signal detection device, comprising: 12. The AC electric signal detection device according to claim 11, wherein the switching selection means of said output means is a switching selection means having a predetermined hysteresis width at a switching boundary. apparatus. 13. An A / D conversion processing means for inputting an AC electric quantity and converting an instantaneous value of the input electric quantity into a digital signal at a predetermined period; and a plurality of digital signals output from the AD conversion processing means. A plurality of calculating means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the AC electric quantity according to different arithmetic methods, and a high value signal of each electric quantity detection signal output by the plurality of arithmetic means is selected. Output means having high value priority means for outputting as an electric quantity detection signal corresponding to an effective value or an average value of the AC electric quantity. 14. The AC electric signal detecting device according to claim 13, wherein said plurality of calculating means uses a digital signal output from said AD conversion processing means and calculates an amplitude of an AC electric quantity according to an amplitude calculating method. A basic operation means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the output voltage of the synchronous machine; and an integral operation for integrating an AC electric quantity using a digital signal output from the AD conversion processing means. A preliminary operation means for calculating an electric quantity detection signal corresponding to an effective value or an average value of the output voltage of the synchronous machine in accordance with at least one of an operation method and a normalization operation method for normalizing an AC electric quantity. An AC electric signal detection device, characterized in that: