JP2023038522A - Digital protective relay device - Google Patents

Abstract

To provide a digital protective relay device which corrects errors of input/output characteristics of an input converter.SOLUTION: A device includes: a plurality of input converters 1a which converts levels of an analog signal; a plurality of A/D converters 1c which converts an analog signal or a phase reference signal by an output of each input converter to a digital signal; a plurality of Fourier transformation computation units which calculates an amplitude value and a phase of each analog signal; a correction arithmetic unit which corrects the amplitude value obtained through calculation by each Fourier transformation computation unit by a first correction amount and corrects the phase obtained through calculation by each Fourier transformation computation unit by a second correction amount; and a protection computation unit which performs a protection computation upon a protection object based on each arithmetic result of the correction arithmetic unit. When an adjustment input signal, an amplitude value of which sequentially varies from the minimum value to the rated value according to the amount of sweep increment, is inputted to a specified input converter, the correction arithmetic unit calculates a first correction amount based on an amplitude value and a second correction amount based on a phase through calculation by a specific Fourier transformation computation unit corresponding to the specific input converter.SELECTED DRAWING: Figure 2

Description

The present invention relates to a digital protection relay device that protects a protected object connected to a power system.

As a conventional technique, for example, an analog signal input from a power system is captured via an input converter, the captured analog signal is converted to a digital signal by an A/D (Analog/Digital) converter, and the converted There is a digital protection control device that calculates an amplitude value from a digital signal, calculates a ratio between the calculated amplitude value and a preset reference amplitude value as a gain correction coefficient, and corrects the gain with the calculated gain correction coefficient (Patent Reference 1). There is also a digital protection control device that calculates the excitation impedance of an input converter that affects the input/output characteristics and corrects the input/output characteristics from the calculated excitation impedance and the input/output characteristics theoretical formula (see Patent Document 2).

JP-A-9-149536 JP 2013-106359 A

Conventionally, an analog signal input from a power system is input to a protection relay device via an input converter in order to isolate it from the power system and convert it to an appropriate input level. The input/output characteristics of the transformer used in this input converter differ depending on the full scale specification, which is the specification of the maximum amplitude of the analog signal input from the electric power system. Therefore, even if the input/output characteristics of the transformer differ depending on the full-scale specifications, errors in the input/output characteristics of the transformer are corrected by digital calculation in order to ensure relay accuracy in the digital protection relay device. For example, an error in input/output characteristics of a transformer when a rated analog signal is applied to an input converter is corrected by gain correction and phase correction.

However, when the input amplitude of the analog signal is less than the rated input amplitude and the minimum input amplitude for which the performance is guaranteed, the magnetic flux density of the transformer is low, the excitation current of the transformer decreases, the excitation impedance of the transformer decreases, and the transformer While the current flowing to the excitation coil side of the transformer increases, the current transmitted from the input side of the transformer to the output side of the transformer decreases, and the input/output error of the transformer increases. Furthermore, since the input/output characteristics of the input converter vary due to individual differences in each transformer, in order to eliminate the characteristic variation, the input/output characteristics should be measured at the minimum input amplitude that guarantees the performance of the transformer alone. It is necessary to select and use those within the criteria range. However, in this case, there is a problem that wasteful costs such as the part cost of the transformer that is out of the criterion range in the sorting and the sorting and measuring work cost are generated.

SUMMARY OF THE INVENTION It is an object of the present invention to correct an error in the input/output characteristics of an input converter regardless of whether the amplitude value of an analog signal input from a power system ranges from the minimum value to the maximum value for guaranteed performance. .

In order to solve the above-mentioned problems, the present invention provides a plurality of inputs for inputting an analog signal representing an analog amount of electric signal from a protected object connected to a power system, converting the level of the input analog signal, and outputting it. a converter, a plurality of analog-to-digital converters for converting analog signals output from each of the input converters into digital signals, and performing Fourier transform processing on the digital signals from the outputs of each of the analog-to-digital converters, a plurality of Fourier transform calculation units for calculating the amplitude value and phase of each of the analog signals; a calculation for correcting the amplitude value by a first correction amount calculated by each of the Fourier transform calculation units; and a calculation by each of the Fourier transform calculation units. A correction calculation unit that executes a calculation for correcting the phase by a second correction amount, a protection calculation unit that executes protection calculation processing for the protection object based on each calculation result of the correction calculation unit, and a phase reference signal a phase reference signal analog-to-digital converter for converting into a digital signal; and performing the Fourier transform processing on the digital signal output from the phase reference signal analog-to-digital converter to obtain an amplitude value and a phase of the phase reference signal. and a Fourier transform calculation unit for the phase reference signal for outputting each calculation result to the correction calculation unit, the correction calculation unit being an AC signal corresponding to the analog signal, the amplitude value of which is , an adjustment input signal, which is a known input signal for adjustment that sequentially changes in a plurality of stages from the low input amplitude minimum value of the analog signal to the rated input amplitude value in accordance with the sweep step amount, among the plurality of input converters. Amplitude of the input signal for adjustment among calculation results of a specific Fourier transform calculation unit corresponding to the specific input converter among the plurality of Fourier transform calculation units on the condition that the input signal is input to a specific input converter The first correction amount is calculated based on the value, and the second correction amount is calculated based on the phase of the input signal for adjustment among the calculation results of the specific Fourier transform calculation section.

According to the present invention, errors in the input/output characteristics of an input converter can be corrected regardless of whether the amplitude value of an analog signal input from a power system is anywhere from the minimum value to the maximum value for guaranteed performance. .

1 is a configuration diagram showing a configuration example of a digital protection relay device according to Embodiment 1 of the present invention; FIG. 1 is a configuration diagram showing a configuration example of hardware and software of a digital protection relay device according to Embodiment 1 of the present invention; FIG. 7 is a flowchart for explaining correction processing when a rated input is applied in the digital protection relay device used in the comparative example; FIG. 10 is an input/output characteristic diagram of a digital protection relay device used in a comparative example by correction processing when a rated input is applied; FIG. 5 is a flow chart for explaining first correction processing during low input amplitude of the digital protection relay device according to the first embodiment of the present invention; FIG. It is a flow chart for explaining the second correction process at the time of low input amplitude of the digital protection relay device according to the second embodiment of the present invention. FIG. 10 is a flow chart for explaining processing to which a second correction processing result is applied at the time of low input amplitude of the digital protection relay device according to Embodiment 2 of the present invention; FIG. It is an input-output characteristic diagram by the 2nd correction|amendment process at the time of the low input amplitude of the digital protection relay apparatus based on Example 2 of this invention. It is a flow chart for explaining the third correction processing of the digital protection relay device according to the third embodiment of the present invention. FIG. 11 is a flow chart for explaining a process to which the third correction process result of the digital protection relay device according to the third embodiment of the present invention is applied; FIG. It is an input-output characteristic diagram by the 3rd correction|amendment process of the digital protection relay apparatus based on Example 3 of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram showing a configuration example of a digital protection relay device according to Embodiment 1 of the present invention. In FIG. 1, the digital protection relay device 1 includes a plurality of input converters 1a, a plurality of analog filters 1b, a plurality of A/D converters 1c, a plurality of digital filters 1d, and a CPU (Central Processing Unit). ) 1e, a work memory 1f, a correction value recording nonvolatile memory 1g, and an input/output interface (I/O interface) 1h, each digital filter 1d, a CPU 1e, a work memory 1f, a correction value recording A nonvolatile memory 1g and an input/output interface 1h are connected to each other via a bus 1i.

Each input converter 1a is divided into a plurality of channels, for example, 16 channels as channels for (three-phase/zero-phase) x (input side + output side) x (voltage + current) and connected to the power system 10, A voltage signal or current signal that is an analog signal (50 Hz or 60 Hz) from the electric power system 10 is converted into a voltage or current level that can be handled by an analog electronic circuit, and the converted voltage or current signal is output to each analog filter 1b. It consists of a transformer (VT) or a current transformer (CT). When the input converter 1a is configured by a transformer, the input converter 1a converts the voltage signal from the electric power system 10 into a voltage signal within the range of ±10V, for example.

One analog filter (analog filter for phase reference signal) 1b out of the plurality of analog filters 1b receives the phase reference signal 20, passes only the signal in the frequency band of the input phase reference signal 20, and performs A/D conversion. (A/D converter for phase reference signal) 1c, and the remaining analog filter 1b receives the analog signal from each input converter 1a and passes only the signal in the frequency band of the input analog signal. and output to each A/D converter 1c. At this time, analog filters for preventing aliasing errors by digital sampling can be used as the analog filters 1b.

Each A/D converter 1c converts an analog signal into a digital signal and transfers the converted digital signal to the CPU 1e. The CPU 1e is composed of a processor functioning as a control section that controls the entire digital protection relay device 1, and takes in the output signal of each digital filter 1b via the bus 1i, and outputs the correction value recorded in the non-volatile memory 1g. Various protection calculation processes are executed based on the control program stored in the work memory 1f or the storage device. A RAM (Random Access Memory) can be used as the work memory 1f, and a conductor memory such as a flash memory (Flash) can be used as the nonvolatile memory 1g.

At this time, for example, when the voltage from one of the plurality of channels changes from 100 V to 0 V, the current changes from 5 A to 20 A, and a zero-phase current is detected, the CPU 1e detects that a ground fault has occurred in this channel. Assuming that it has occurred, a protection calculation process is executed to operate a protection relay for protecting the transformer to be protected.

FIG. 2 is a configuration diagram showing an example configuration of hardware and software of the digital protection relay device according to the first embodiment of the present invention. In FIG. 2, the hardware 2a of the digital protection relay device 1 is composed of an input converter 1a, a plurality of analog filters 1b, a plurality of A/D converters 1c, and a correction value recording non-volatile memory 1g. . The software 2b of the digital protection relay device 1 includes a specific Fourier transform calculation unit 2c that performs Fourier transform processing on the digital signal output from the A/D converter 1c that converts the phase reference signal 20 into a digital signal, A phase reference signal Fourier transform calculation unit 2c that performs Fourier transform processing on the digital signal output from the A/D converter 1c that converts the analog signal into a digital signal, and the amplitude of the signal Fourier-transformed by each Fourier transform calculation unit 2c. Computation for correcting A0, A1 and phases θ0, θ1 with each correction value (first correction amount and second correction amount) recorded in correction value recording non-volatile memory 1g is performed to correct amplitude Ac1 and phase θc1. A correction calculation unit 2d that generates a processing signal and a protection calculation based on the correction processing signal based on the calculation result of the correction calculation unit 2d. and a calculation unit 2e. Each calculation unit is composed of a control program. At this time, the correction calculation unit 2d performs calculation for correcting the amplitude value calculated by each Fourier transform calculation unit 2c by the first correction amount and calculation for correcting the phase calculated by each Fourier transform calculation unit 2c by the second correction amount. Execute. The protection calculation unit 2e also executes calculations for detecting ground faults and short-circuit accidents in each channel based on the calculation result of the correction calculation unit 2d. FIG. 2 shows only the input converter 1a, the analog filter 1b and the A/D converter 1c, which are used for correction calculation among the hardware 2a of the digital protection relay device 1. FIG.

FIG. 3 is a flowchart for explaining correction processing when a rated input is applied to the digital protection relay device used in the comparative example. In FIG. 3, the digital protection relay device used in the comparative example has the rated input amplitude A _R1 of the analog signal, the theoretical value of the rated input amplitude A _T1 , the gain correction amount G _CR1 , the rated input phase θ _R1 of the analog signal, the reference signal The phase θ _REF and the phase correction amount θ _CR1 are taken in as input information (S1), and based on the input information, the gain correction amount G _CR1 and the phase correction amount θ _CR1 at the rated input are calculated (S2). At this time, the gain correction amount G _CR1 at the rated input is calculated from gain correction amount G _CR1 = theoretical input amplitude A _T1 / rated input amplitude A _R1 . The phase correction amount θ _CR1 is calculated from the phase correction amount θ _CR1 =phase correction amount θ _CR1 −reference signal phase θ _REF .

FIG. 4 shows an input/output characteristic diagram of the digital protection relay device used in the comparative example by correction processing when a rated input is applied. As shown in Fig. 4, in the comparative example, the gain correction amount G _CR1 and the phase correction amount θ _CR1 are calculated based on the analog signal at the rated input. I know it will grow.

FIG. 5 is a flow chart for explaining the first correction process during low input amplitude of the digital protection relay device according to the first embodiment of the present invention. This process is a process for averaging correction errors as a correction process for low input amplitude at the time of shipment from the factory.

In FIG. 5, for example, the specific input converter 1a shown in FIG. The amplitude value is the minimum low _input amplitude value of the analog signal (minimum value for guaranteed performance, e.g., several tens of mV or several 10 mA) to the rated input amplitude value (maximum value for guaranteed performance, eg, 110 V or 5 A). The input signal for adjustment is, for example, a signal that sequentially changes in steps of 0.1V from several tens of mV to 110V. Note that performance guarantee means guaranteeing the performance of the digital protection relay device 1 .

The correction calculation unit 2d calculates the low input amplitude A _L [i], the low input amplitude theoretical value A _LT [i], the low input gain correction amount G _CL [i], the low input phase θ _L [i], the reference signal phase θ Information about _REF [i], low input phase correction amount θ _CL [i], low input gain average correction amount G _AVL , low input phase average correction amount θ _AVL , low input amplitude sweep step amount ΔA _L , rated input amplitude A _R1 (S11). At this time, the correction calculation unit 2d calculates (A _R1 −A _L )/ΔA _L =N (N is a natural number), A _L [i]=A _R1 , i=0, A _L [0]=low input amplitude minimum Treat as a value.

When the adjustment input signal is input to the specific input converter 1a, the correction calculator 2d converts each calculation result of the specific Fourier transform calculator 2c corresponding to the specific input converter 1a and the phase reference signal. Each calculation result of the Fourier transform calculation unit 2c for adjustment is taken in, and the low input gain correction amount G _CL [i] for the amplitude value of the input signal for adjustment and the low input phase correction amount θ _CL [i] for the phase of the input signal for adjustment are calculated. It is calculated for each sweep step amount (low input amplitude sweep step amount ΔA _L ) (S12). At this time, the correction calculation unit 2d calculates the low input gain correction amount G _CL [i]=low input amplitude theoretical value A _LT [i] defined in the phase reference signal 20/low input amplitude A _L [ of the adjustment input signal i], and the low input phase correction amount θ _CL [i]=low input phase θ _L [i] of adjustment input signal−reference signal phase θ _REF .

Next, based on the calculation result of step S12, the correction calculation unit 2d calculates the low input gain average correction amount G _AVL and the low input phase average correction amount θ _AVL for each sweep step amount (low input amplitude sweep step amount ΔA _L ). (S13). At this time, the correction calculation unit 2d calculates the average low input gain correction amount G _AVL =the average low input gain correction amount G _AVL (initial value)+the low input gain correction amount G _CL [i]/N. Average correction amount θ _AVL =low input phase average correction amount θ _AVL (initial value)+low input phase correction amount θ _CL [i]/N.

Next, the correction calculation unit 2d executes a process of setting i=i+1 (S14), and then determines whether i is smaller than N or equal to N (S15). is smaller than or equal to N, the process proceeds to step S12, and the processes of steps S12 to S15 are repeated. 1g (S16), and then the processing of this routine ends.

With the above processing, the correction calculation unit 2d obtains the average value of the theoretical amplitude values for each sweep step amount specified for the phase reference signal, and the adjustment input signal among the calculation results of the specific Fourier transform calculation unit 2c. A gain correction amount is calculated as a first correction amount from the ratio of the amplitude value and the average value of the amplitude values for each sweep step amount, and the phase of the input signal for adjustment is calculated from the calculation result of the specific Fourier transform calculation unit 2c. Then, the phase correction amount is calculated as the second correction amount from the difference between the phase average value for each sweep step amount and the phase of the phase reference signal.

According to this embodiment, even if the amplitude value of the analog signal input from the electric power system is anywhere from the minimum value to the maximum value of the performance guarantee, the signal range of the minimum value to the maximum value Errors in the input/output characteristics of the input transducer can be averaged and corrected, and as a result, the errors in the input/output characteristics of the input transducer are averaged over the signal range from the minimum value to the maximum value. The corrected gain correction amount and phase correction amount can be obtained.

FIG. 6A is a flow chart for explaining second correction processing at low input amplitude of the digital protection relay device according to the second embodiment of the present invention. This process is a correction process for low input amplitude at the time of shipment from the factory, and calculates a correction error by linear approximation of the least squares method. The hardware and software configurations of the digital protection relay device in the second embodiment are the same as those in the first embodiment.

In FIG. 6A, for example, the specific input converter 1a shown in FIG. 2 receives an adjustment input signal that sequentially changes in steps of 0.1 V from several tens of mV to 110 V in multiple stages, as in the case of the first embodiment. is entered.

The correction calculation unit 2d calculates the low input amplitude A _L [i], the low input amplitude theoretical value A _LT [i], the low input gain correction amount G _CL [i], the low input phase θ _L [i], the reference signal phase θ _REF [i], low input phase correction amount θ _CL [i], low input gain correction amount calculation value G _Lcalc , low input phase correction amount calculation value θ _Lcalc , low input amplitude sweep step amount ΔA _L , rated input amplitude A _R1 The processing is started for the information related to (S21). At this time, the correction calculation unit 2d calculates (A _R1 −A _L )/ΔA _L =N (N is a natural number), A _L [i]=A _R1 , i=0, A _L [0]=low input amplitude minimum It is processed as a value (S21).

Next, the correction calculation unit 2d calculates the low input gain correction amount G _CL from the low input amplitude theoretical value A _LT [i] defined in the phase reference signal 20 and the low input amplitude A _L [i] of the input signal for adjustment. [i] is calculated, and the low input phase correction amount θ _CL [i] is calculated from the low input phase θ _L [i] of the adjustment input signal and the reference signal phase θ _REF of the phase reference signal 20 (S22). . At this time, the correction calculation unit 2d calculates the low input gain correction amount G _CL [i]=low input amplitude theoretical value A _LT [i]/low input amplitude A _L [i], and calculates the low input phase correction amount θ _CL [i] = low input phase θ _L [i] - reference signal phase θ _REF .

Next, the correction calculation unit 2d executes a process of setting i=i+1 (S23), and then determines whether i is smaller than N or equal to N (S24). is smaller than or equal to N, the process proceeds to step S22, the processes of steps S22 to S24 are repeated, and when i becomes greater than N, i is set to 0 and the loop count i is reinitialized. (S25).

Through the processing from step S22 to step 24, the correction calculation unit 2d performs low input gain correction based on the low input amplitude theoretical value A _LT [i] of the phase reference signal 20 and the low input amplitude A _L [i] of the adjustment input signal. The amount G _CL [i] is calculated for each sweep step amount (low input amplitude sweep step amount ΔA _L ), and the low input phase θ _L [i] of the adjustment input signal and the reference signal phase θ _REF of the phase reference signal 20 are calculated. , the low input phase correction amount θ _CL [i] is calculated for each sweep step amount (low input amplitude sweep step amount ΔA _L ).

Next, based on the calculation results of steps S22 to S24, the correction calculation unit 2d uses the approximate straight lines for gain correction and phase correction as linear approximation coefficients of the least-squares method to obtain gain correction approximate straight line calculation coefficients Yg, Xg _{, and} Xgsq. , XYg and phase correction approximate linear coefficients Yp, Xp, Xpsq, XYp are calculated (S26). At this time, the correction calculation unit 2d calculates gain correction approximate straight line calculation coefficient Xg=Xg (initial value)+low input amplitude A _L [i], and gain correction approximate straight line calculation coefficient Yg=Yg (initial value)+low input amplitude. Calculated as input gain correction amount G _CL [i], gain correction approximate straight line calculation coefficient Xgsq = Xgsq (initial value) + low input amplitude A _L [i] × low input amplitude A _L [i], gain correction Approximate straight line calculation coefficient XYg=XYg (initial value)+low input amplitude A _L [i]×low input gain correction amount G _CL [i]. Further, the correction calculation unit 2d calculates the phase correction approximate linear coefficient Xp = Xp (initial value) + low input amplitude A _L [i], and the phase correction approximate linear coefficient Yp = Yp (initial value) + low input phase correction. _Phase correction approximate linear coefficient Xpsq = Xpsq (initial value) + low input amplitude A _L [i] × low input amplitude A _L [i], phase correction approximate linear coefficient XYp = XYp (initial value) + low input amplitude A _L [i] x low input gain correction amount G _CL [i].

Next, the correction calculation unit 2d executes a process of setting i=i+1 (S27), and then determines whether i is smaller than N or equal to N (S28). When i is smaller than N or equal to N, the process proceeds to step S26, the processes of steps S26 to S28 are repeated, and when i becomes greater than N, the process proceeds to step S29.

Next, based on the calculation results of steps S26 to S28, the correction calculation unit 2d calculates the slope a _G and the intercept b _G of the gain correction approximate straight line and the slope a _θ and the intercept b G of the phase correction approximate straight line at the low input amplitude A _L . b _θ is calculated, the low input gain correction amount calculation value G _Lcalc is calculated from the calculation result (gain correction approximate linear expression), and the low input phase correction amount calculation value θ _Lcalc is calculated from the calculation result (phase correction approximate expression). (S29), and then the processing of this routine is terminated.

At this time, the correction calculation unit 2d calculates the slope a _G of the gain correction approximate straight line as (N×XYg−Xg×Yg)/(N×Xgsq−Xg×Xg), and the intercept b _G = of the gain correction approximate straight line Calculate as (Yg x Xgsq - Xg x XYg)/(N x Xgsq - Xg x Xg). Further, the correction calculation unit 2d calculates the gradient a _θ of the phase correction approximate straight line as (N×XYp−Xp×Yp)/(N×Xgsq−Xg×Xp), and the intercept b _{θ of the phase correction approximate straight line =} ( Yp x Xpsq - Xp x XYp)/(N x Xpsq - Xg x Xp).

Furthermore, the correction calculation unit 2d calculates the low input gain correction amount calculation value G _Lcalc = slope a _G of gain correction approximate straight line × low input amplitude A _L + intercept b _G of gain correction approximate straight line, and calculates the low input phase correction amount. Calculated value θ _Lcalc = gradient a _θ of phase correction approximate straight line × low input amplitude A _L + intercept b _θ of phase correction approximate straight _line . The low input phase correction amount calculated value θ _Lcalc is stored in the correction value recording non-volatile memory 1g as the second correction amount.

FIG. 6B is a flow chart for explaining the process to which the second correction process result is applied when the input amplitude is low in the digital protection relay device according to the second embodiment of the present invention.

In FIG. 6B, for example, an analog signal is input to each input converter 1a. The correction calculation unit 2d calculates the input amplitude A _in of the analog signal, the input phase θ _in of the analog signal, the rated amplitude A _R of the analog signal, the low input amplitude A _L of the analog signal, the rated gain correction amount G _CR1 of the analog signal, the analog signal Information about the rated phase correction amount θ _CR1 of the signal is input, and information about the low input gain correction amount calculation value G _Lcalc and the low input phase correction amount calculation value θ _Lcalc calculated in step S29 are input. Then, the process of calculating the intermediate amplitude value A _MID =(A _R +A _L )/2 between the rated input amplitude A _R and the low input amplitude A _L , the amplitude after correction A _out , and the phase after correction θ _out is started ( S31).

Next, when the correction calculation unit 2d calculates an intermediate amplitude value A _MID =(A _R +A _L )/2 between the rated input amplitude A _R of the analog signal and the low input amplitude A _L of the analog signal, the input amplitude It is determined whether A _in is greater than the intermediate amplitude value A _MID (S32), and if it is determined that the input amplitude A _in is greater than the intermediate amplitude value A _MID , corrected amplitude A _out and corrected phase θ _out is calculated (S33), and then the processing of this routine ends. At this time, the correction calculation unit 2d calculates as corrected amplitude A _{out =} input amplitude A _in × rated gain correction amount G _CR1 , and calculates as corrected phase θ _out = input phase θ _in × rated phase correction amount θ _CR1. .

On _the condition that the input amplitude A _in is greater than _the intermediate amplitude value A _MID , the correction calculation unit 2d calculates the post-correction amplitude A _out (first correction post-correction phase θ _out (phase after first correction) is calculated from the input phase θ _in of the analog signal and the rated phase correction amount θ _CR1 , and based on the calculated amplitude after first correction The amplitude value of the analog signal calculated by the Fourier transform calculator 2c is corrected, and the phase of the analog signal calculated by the Fourier transform calculator 2c is corrected based on the calculated phase after the first correction.

On the other hand, if it is determined in step S32 that the input amplitude A _in is smaller than the intermediate amplitude value A _MID , the correction calculation unit 2d determines whether the input amplitude A _in satisfies the condition of 0≦A _in <A _MID . is determined (S34). If it is determined that the input amplitude A _in exists between 0 and the intermediate amplitude value A _MID , the corrected amplitude A _out and the corrected phase θ _out are calculated (S35), and then the processing of this routine ends. do. At this time, the correction calculation unit 2d calculates as corrected amplitude A _{out =} input amplitude A _in × low input gain correction amount calculation value G _Lcalc , corrected phase θ _{out =} input phase θ _in × low input phase correction amount calculation It is calculated as the value θ _Lcalc .

Based on the input amplitude A _in of the analog signal and the low _input gain correction amount _calculation value _{G Lcalc} Calculate corrected amplitude A _out (second corrected amplitude) and calculate corrected phase θ _out (second corrected phase) from analog signal input phase θ _in and low input phase correction value θ _Lcalc Then, based on the calculated amplitude after the second correction, the amplitude value of the analog signal calculated by the Fourier transform calculation unit 2c is corrected, and the amplitude value of the analog signal calculated by the Fourier transform calculation unit 2c is corrected based on the calculated phase after the second correction. Correct the phase.

Further, when it is determined in step S34 that the input amplitude A _in does not satisfy the condition of 0≦A _in <A _MID , the correction calculation unit 2d detects an amplitude value abnormality (S36), and then performs this routine. end the processing.

FIG. 7 shows an input/output characteristic diagram of the digital protection relay device according to the second embodiment of the present invention when the input amplitude is low, according to the second correction process. In this embodiment, when the input amplitude is low, the correction error is corrected by the one calculated by the linear approximation of the method of least squares. Therefore, as shown in FIG. It can be seen that the characteristics are smaller than those of the example.

According to this embodiment, even if the amplitude value of the analog signal input from the electric power system is anywhere from the minimum value to the maximum value of the performance guarantee, the signal range of the minimum value to the maximum value Errors in input/output characteristics of an input converter can be corrected by linear approximation of the least-squares method, and as a result, a gain correction amount and a phase correction amount corrected by the linear approximation of the least-squares method can be obtained. can be done. Further, according to this embodiment, the case where the input amplitude A _in exists between 0 and the intermediate amplitude value _AMID and the case where the input amplitude _Ain is greater than the intermediate amplitude value _AMID are divided into: It is possible to correct the amplitude value of the analog signal input from the power system.

FIG. 8A is a flowchart for explaining third correction processing of the digital protection relay device according to the third embodiment of the present invention; This process sweeps a known input signal for adjustment (adjustment input signal) that varies from the minimum input amplitude to the maximum amplitude, the full-scale input amplitude, which guarantees the performance of the digital protection relay device according to the present invention. , and creates a lookup table of gain correction values and phase correction values corresponding to the input amplitude of the input adjustment signal. The hardware and software configurations of the digital protection relay device in the third embodiment are the same as those in the first embodiment.

In FIG. 8A, for example, the specific input converter 1a shown in FIG. 2 receives an adjustment input signal that sequentially changes in steps of 0.1 V from several tens of mV to 110 V in multiple stages, as in the case of the first embodiment. is entered.

The correction calculation unit 2d receives the input amplitude A[i] of the adjustment input signal, the input amplitude theoretical value A _T [i] defined in the phase reference signal 20, the input gain correction amount G _C [i], the adjustment input signal , the input phase θ[i] of the phase reference signal 20, the reference signal phase _θREF [i] of the phase reference signal 20, the input phase correction amount _θC [i], and the full-scale input amplitude _AFS of the input signal for adjustment. Start, input amplitude sweep step ΔA, (A _FS -A[0])/ΔA=N (N is a natural number), A[N]=A _FS , i=0, A[0]=low input amplitude minimum A process of initializing as a value is executed (S41).

Next, the correction calculation unit 2d calculates the input gain correction amount G _C [i] of the adjustment input signal and the input phase correction amount θ _C [ of the adjustment input signal based on the calculation results of the Fourier transform calculation units 2c. i] is calculated (S42). At this time, the correction calculation unit 2d calculates the input gain correction amount G _C [i]=the input amplitude theoretical value A _T [i] defined in the phase reference signal 20/the input amplitude A[i] of the input signal for adjustment. Then, input phase correction amount θ _C [i]=input phase θ[i] of adjustment input signal−reference signal phase θ _REF of phase reference signal 20 is calculated.

Next, the correction calculation unit 2d includes a gain correction lookup table that outputs an input gain correction amount G _C [i] corresponding to the input amplitude A[i] and an input phase correction amount θ corresponding to the input amplitude A[i]. As the process of recording the phase correction lookup table that outputs _C [i], the input gain correction amount G _C [i] corresponding to the input amplitude A[i] is recorded in the gain correction lookup table GLLUT as the first correction amount. Then, the input phase correction amount θ _C [i] corresponding to the input amplitude A[i] is recorded in the phase lookup table PLUT as the second correction amount (S44). The gain correction lookup table GLLUT and the phase lookup table PLUT are stored in the correction value recording nonvolatile memory 1g.

Next, the correction calculation unit 2d executes a process of setting i=i+1 (S44), and then determines whether i is smaller than N or equal to N (S45). When i is smaller than or equal to N, the process proceeds to step S42, and the processes of steps S42 to S45 are repeated. When i becomes larger than N, the process of this routine ends.

Through the processing of steps S42 to S45, the correction calculation unit 2d obtains the theoretical amplitude value for each sweep step amount defined for the phase reference signal 20, and the adjustment input signal among the calculation results of the Fourier transform calculation unit 2c. The input gain correction amount corresponding to each sweep step amount is calculated as the gain correction amount from the ratio of the amplitude value of each sweep step amount (input amplitude sweep step amount ΔA) to the amplitude value of each sweep step amount. The input gain correction amount corresponding to the step amount is recorded in the gain correction lookup table GLUT as the first correction amount, and the phase of the input signal for adjustment among the calculation results of the Fourier transform calculation unit 2c is determined for each sweep step amount. The input phase correction amount corresponding to each sweep step is calculated as a phase correction amount from the difference between the phase of the phase reference signal and the phase of the phase reference signal, and the input phase correction amount corresponding to each sweep step is calculated as a second correction amount. is recorded in the phase lookup table PLUT as

FIG. 8B is a flowchart for explaining processing for applying the result of the third correction processing of the digital protection relay device according to the third embodiment of the present invention;

In FIG. 8B, for example, an analog signal is input to each input converter 1a. The correction calculation unit 2d receives the input amplitude A _in of the analog signal, the input phase θ _{in of} the analog signal, the gain correction lookup table GLUT, the phase lookup table PLUT, the lookup table input A[i], the input gain correction amount G _C [i], input phase correction amount θ _C [i], corrected amplitude A _out , and corrected phase θ _out are processed (S51).

The correction calculation unit 2d receives information indicating each calculation result of each Fourier transform calculation unit 2c, and calculates a lookup table input A[i] based on the input amplitude A _in of the analog signal among the input information. (S52).

Next, the correction calculator 2d outputs the input gain correction amount G _C [i] from the gain correction lookup table GLUT, and outputs the input phase correction amount θ _C [i] from the phase lookup table PLUT (S53). .

Next, the correction calculation unit 2d calculates the corrected amplitude A _out and the corrected phase θ _out based on the information input in step S51 and the information output in step S53, and then terminates the processing of this routine. do. At this time, the correction calculation unit 2d calculates as corrected amplitude A _out =input amplitude A _in ×input gain correction amount G _C [i], corrected phase θ _out =input phase θ _in -input phase correction amount θ _C Calculated as [i].

When an analog signal whose amplitude value includes any of the sweep step amounts (input amplitude sweep step amount ΔA) is input to each input converter 1a, the correction calculation unit 2d adjusts the sweep step specified by the amplitude value of the analog signal. The amount of input gain correction corresponding to the amount is extracted from the gain correction lookup table GLUT, the amplitude value of the analog signal calculated by the Fourier transform calculation unit 2c is corrected based on the extracted amount of input gain correction, and the amplitude value of the analog signal is extracted from the phase lookup table PLUT, and the phase of the analog signal calculated by the Fourier transform calculation unit 2c is corrected based on the extracted input phase correction amount.

FIG. 9 shows an input/output characteristic diagram by the third correction processing of the digital protection relay device according to the third embodiment of the present invention. In this embodiment, the input signal for adjustment that changes from the minimum input amplitude that guarantees the performance of the digital protection relay device to the maximum amplitude, that is, the full-scale input amplitude is swept, and the signal range from the minimum value to the maximum value is swept. Since the error in the input/output characteristics of the input converter has been corrected over the It can be seen that the error in the range of is smaller than that of the comparative example shown in FIG.

According to this embodiment, even if the amplitude value of the analog signal input from the electric power system is anywhere from the minimum value to the maximum value of the performance guarantee, the signal range of the minimum value to the maximum value It is possible to obtain the gain correction amount and the phase correction amount in which the error in the input/output characteristics of the input converter is corrected. For example, even if an analog signal from a low input signal range of several tens of mA and several tens of mV to a high input signal range of full scale is input to the input converter, the input conversion will not be possible from the low input signal range to the high input signal range. It is possible to obtain the input gain correction amount and the input phase correction amount in which errors in the input/output characteristics of the device are corrected.

The present invention is not limited to the embodiments described above, but includes various modifications and equivalent configurations within the scope of the appended claims. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and the present invention is not necessarily limited to those having all the described configurations.

In addition, each configuration, function, etc. described above may be realized by hardware, for example, by designing a part or all of them with an integrated circuit, and a processor interprets and executes a program that realizes each function. You may implement|achieve by software by doing.

Information such as programs, tables, files, etc. that realize each function is stored in storage devices such as memory, hard disk, SSD (Solid State Drive), or IC (Integrated Circuit) card, SD card, DVD (Digital Versatile Disc) recording Can be stored on media.

1 digital protection relay device, 1a input converter, 1b analog filter, 1c A/D converter, 1d digital filter, 1e CPU, 1f work memory, 1g nonvolatile memory, 1h input/output interface, 1i bus, 2a hardware, 2b Software, 2c Fourier transform calculation unit, 2d correction calculation unit, 2e protection calculation unit

Claims (7)

a plurality of input converters for inputting an analog signal indicating an analog amount of electric signal from a protected object connected to a power system, converting the level of the input analog signal, and outputting the analog signal;
a plurality of analog-to-digital converters for converting analog signals output from the input converters into digital signals;
a plurality of Fourier transform calculation units that perform Fourier transform processing on the digital signals output from the analog/digital converters to calculate amplitude values and phases of the analog signals;
a correction calculation unit that performs a calculation for correcting the amplitude value calculated by each Fourier transform calculation unit by a first correction amount and a calculation for correcting the phase by a second correction amount calculated by each Fourier transform calculation unit;
a protection calculation unit that executes protection calculation processing for the protection object based on each calculation result of the correction calculation unit;
a phase reference signal analog-to-digital converter for converting the phase reference signal into a digital signal;
A phase for performing the Fourier transform process on the digital signal output from the phase reference signal analog-to-digital converter, calculating the amplitude value and phase of the phase reference signal, and outputting each calculation result to the correction calculation unit. and a Fourier transform calculation unit for reference signals,
The correction calculation unit is
The adjusting input signal, which is an alternating current signal corresponding to the analog signal and whose amplitude value changes sequentially in a plurality of stages from a low input amplitude minimum value of the analog signal to a rated input amplitude value according to the sweep step amount, is provided in the plurality of out of the plurality of Fourier transform calculation units, on the condition that an input to a specific input converter among the input converters of the calculating the first correction amount based on the amplitude value of the input signal for adjustment, and calculating the second correction amount based on the phase of the input signal for adjustment among the calculation results of the specific Fourier transform calculation section; A digital protection relay device characterized by: The digital protection relay device of claim 1, wherein
The correction calculation unit is
A gain correction amount indicating a ratio between a theoretical amplitude value specified for the phase reference signal and an amplitude value of the input signal for adjustment calculated by the specific Fourier transform calculation unit is used as the first correction amount for each sweep step amount. and the phase correction amount indicating the difference between the phase of the adjustment input signal calculated by the specific Fourier transform calculation unit and the phase of the phase reference signal calculated by the phase reference signal Fourier transform calculation unit A digital protection relay device, wherein the second correction amount is calculated for each sweep step amount. The digital protection relay device of claim 1, wherein
The correction calculation unit is
The gain correction amount indicating the ratio of the average value of the theoretical amplitude values specified for the phase reference signal and the average value of the amplitude values of the input signal for adjustment among the calculation results of the specific Fourier transform calculation unit is determined as the second gain correction amount. One correction amount is calculated for each of the sweep increments, and among the calculation results of the specific Fourier transform calculation unit, the average value of the phase of the adjustment input signal and the calculation result of the phase reference signal Fourier transform calculation unit A digital protection relay device, wherein a phase correction amount indicating a difference from the phase of the phase reference signal is calculated as the second correction amount for each of the sweep increments. The digital protection relay device of claim 1, wherein
The correction calculation unit is
A theoretical amplitude value for each sweep increment defined in the phase reference signal, and an amplitude value of the adjustment input signal among the calculation results of the specific Fourier transform calculation unit, which is an amplitude for each sweep increment A gain correction amount indicating a ratio to a value is calculated for each sweep step amount, and based on the calculated gain correction amount for each sweep step amount and the amplitude value of the adjustment input signal for each sweep step amount, calculating a gain correction amount calculated value by linear approximation of the least squares method as the first correction amount;
the phase of the adjustment input signal among the calculation results of the specific Fourier transform calculation unit, the phase for each sweep step amount, and the phase reference signal among the calculation results of the phase reference signal Fourier transform calculation unit; A phase correction amount indicating a difference from the phase is calculated for each sweep step amount, and based on the calculated phase correction amount for each sweep step amount and the amplitude value for each sweep step amount of the adjustment input signal, A digital protection relay device, wherein a phase correction amount calculated value by the linear approximation of the least squares method is calculated as the second correction amount. The digital protection relay device of claim 4, wherein
The correction calculation unit is
When the analog signal is input to the input converter, on the condition that the input amplitude of the analog signal is larger than an intermediate amplitude value intermediate between the minimum low input amplitude value and the rated input amplitude value, calculating the amplitude after the first correction from the input amplitude of the analog signal and the rated gain correction amount, calculating the phase after the first correction from the input phase of the analog signal and the rated phase correction amount, and calculating the first correction; correcting the amplitude value of the analog signal calculated by the Fourier transform calculation unit based on the post-amplitude, and correcting the phase of the analog signal calculated by the Fourier transform calculation unit based on the calculated phase after the first correction; ,
calculating a second corrected amplitude from the input amplitude of the analog signal and the calculated gain correction amount on condition that the input amplitude of the analog signal is between 0 and the intermediate amplitude value; calculating a phase after the second correction from the input phase of the analog signal and the calculated value of the phase correction amount, and correcting the amplitude value of the analog signal calculated by the Fourier transform calculation unit based on the calculated amplitude after the second correction; and correcting the phase of the analog signal calculated by the Fourier transform calculation section based on the calculated second corrected phase. The digital protection relay device of claim 1, wherein
The correction calculation unit is
A theoretical amplitude value for each sweep increment defined in the phase reference signal; and an amplitude value for each sweep increment, which is an amplitude value of the adjustment input signal among the calculation results of the Fourier transform calculation unit. calculating an input gain correction amount indicating a ratio of for each sweep step amount, and recording the input gain correction amount corresponding to each calculated sweep step amount as a first correction amount in a gain correction lookup table;
The phase of the adjustment input signal among the calculation results of the Fourier transform calculation unit, the phase for each sweep step amount, and the phase of the phase reference signal among the calculation results of the phase reference signal Fourier transform calculation unit. is calculated for each sweep step amount, and the input phase correction amount corresponding to each calculated sweep step amount is recorded in the phase lookup table as the second correction amount. A digital protection relay device characterized by: The digital protection relay device of claim 6, wherein
The correction calculation unit is
When the analog signal whose amplitude value includes one of the sweep steps is input to the input converter, the input gain correction amount corresponding to the sweep step specified by the amplitude value of the analog signal is set to the gain. Extracting from the correction lookup table, correcting the amplitude value of the analog signal calculated by the Fourier transform calculation unit based on the extracted input gain correction amount,
An input phase correction amount corresponding to the sweep step amount specified by the amplitude value of the analog signal is extracted from the phase lookup table, and the Fourier transform calculation unit calculates the input phase correction amount based on the extracted input phase correction amount. A digital protection relay device characterized by correcting the phase of an analog signal.

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