JP5106172B2 - Digital protection / control device monitoring system - Google Patents

Description

  The present invention relates to a digital protection or control device monitoring system that performs a predetermined protection operation or control operation using a grid electricity quantity acquired from a power system, and more particularly, a digital protection or control device that monitors digital data. It relates to the monitoring method.

  A voltage transformer PD, a current transformer as an input unit of a digital protection or control device (hereinafter abbreviated as a digital protection / control device) that performs a predetermined protection calculation or control calculation using a system electric quantity acquired from the power system There are an input conversion unit that converts a system electric quantity output from the CT into an appropriate size, and an analog input circuit that converts the analog quantity output from the input conversion unit into a digital quantity and outputs the digital quantity.

This analog input circuit is composed of an analog filter and sample-and-hold circuit provided for each channel, a multiplexer and an analog / digital converter provided in common for each channel, and these include an operational amplifier, Since components such as resistors and capacitors are used, if these components deteriorate over time, the error of the analog input circuit increases, and the performance of the protection operation or control operation decreases.
For this reason, the analog input circuit conventionally performs accuracy checking by automatic monitoring by various methods.

As an example, there is a method described in Patent Document 1. In this method, a system electric quantity i _L and a monitoring signal i _T are superimposed and input to an analog filter of a plurality of channels provided in an analog input circuit to perform digital conversion for each channel, and a digital filter is provided for each channel. Each of the harmonic monitoring signal components is extracted, and the amplitude calculation value of the harmonic monitoring signal component is equal to or greater than a predetermined value of the monitoring signal set in advance, and two different harmonic monitoring signal components This is a monitoring method that determines that an analog filter is defective when the magnitude of the vector sum is equal to or greater than a predetermined value.

As another example, there is a method described in Patent Document 2. Reference this method, the monitoring signal i _T synchronized with the timing signal of the analog-to-digital conversion so as to overlap the input to the analog filter with system electrical quantities i _L, and, in the constant phase relationship with the monitoring signal i _T signal to enable analog-to-digital converter without passing through the analog filter constitutes the analog input circuit, when inputting only monitoring signal i _T to an analog filter, previously stores a monitoring signal data analog-to-digital converter In addition, the monitoring signal stored in advance in synchronization with the phase of the reference signal from the input electricity amount data (i _L + i _T ) when the grid electricity amount and the monitoring signal are superposed at all times. The data is subtracted to remove the monitoring signal component from the relay introduction amount.
JP-A-6-261440 JP-A-8-23624

  In the case of Patent Document 1, in order to monitor the analog filter, as described above, the system electrical quantity and the monitoring signal are superimposed and input to the analog filter for each channel, and digitally converted, and the monitoring filter extracted via the analog filter is used. The problem is that two types of operations must be performed in order to perform the magnitude determination of the signal component and the magnitude determination of the vector sum of two monitoring signals obtained via two different analog filters. Remained as. That is, there remains a problem that two types of operations, that is, a calculation for detecting a failure of each analog filter and a calculation for detecting a phase shift failure of the analog unit must be performed.

  Further, in Patent Document 2, in order to detect a failure of the analog filter, the monitoring digital data obtained by inputting the monitoring signal to the analog filter and digitally converted so that the monitoring signal input does not affect the relay operation. The problem remains that two types of data must be generated by subtracting the monitoring signal from the digitally converted data.

  Therefore, the object of the present invention is to eliminate the above two problems without requiring two types of operations: an operation for detecting an analog filter failure and an operation for detecting an analog unit phase shift failure. Another object of the present invention is to provide a digital protection / control device that does not require two types of data for monitoring an analog filter.

In order to achieve the above object, the invention according to claim 1 introduces a system electric quantity taken from an electric power system into an analog filter and converts it into digital data, and at the same time, the analog filter has a predetermined size at a predetermined frequency. In the monitoring system of the digital protection / control device that monitors the analog input circuit using the output signal of the analog input circuit configured to superimpose the monitoring signal on the grid electricity quantity, the analog / digital A monitoring signal generating means for generating a monitoring signal synchronized with a conversion timing signal; and when the monitoring signal is sampled with a sampling signal corresponding to the analog / digital conversion timing signal, one period of the monitoring signal Sampler that sequentially counts the sampling number of the sampling signal distributed over Number counting means, application control means for starting superimposition of the monitoring signal on the grid electrical quantity when the sampling number counting means has a predetermined sampling number, and the sampling number corresponding to the sampling number after the superimposition start of the monitoring signal Storage means for storing the digital data of the monitoring signal for a predetermined period; storage data selection means for receiving the sampling number output from the sampling number counting means and selecting the storage data of the storage circuit means; and Subtracting means for subtracting the output of the storage data selecting means from the digital data when the monitoring signal is superposed to output data for monitoring and protection operation, and monitoring from the data for monitoring and protection operation Extracts the signal and detects whether the size of the extracted monitoring signal is within a predetermined tolerance Te, characterized in that it comprises an analog filter monitoring means for determining whether a failure of the analog filter, the.

  According to the present invention, by sharing the monitoring data and the relay calculation data, it is possible to detect the failure of the analog filter by monitoring one type of data, and it is not necessary to compare with other channels. Thus, it is possible to provide a digital protection / control device that can identify a defective channel by simple processing and can reduce the processing load for calculating data and the memory consumption.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram illustrating a digital protection / control device according to a first embodiment of the present invention, paying attention to an analog input circuit, and FIG. 2 is a monitoring and relay by the digital protection / control device of this embodiment. FIG. 3 is a waveform diagram for explaining the common signal output means 30 for monitoring / relay calculation, and FIG. 4 is an analog filter monitor by the digital protection / control device of this embodiment. It is a block diagram which shows a means.

(Constitution)
First, referring to FIG. 1, the configuration of the analog input circuit of the digital protection / control apparatus will be described. Reference numeral 100 denotes a digital protection / control device. Levels in the digital protection and control device 100, the system voltage v and the system current i _L is a system electric quantity, that can be handled is introduced into the input transducer 1 via respective voltage transformer PD and the current transformer CT and an electronic circuit And then input to the analog input circuit 20. The analog input circuit 20 are input to the analog filter 2 _-1 and _2-2 from the system voltage v and the system current i _L entered to remove the high frequency components. Incidentally, these analog filters _{2 -1} and _2-2 is also input monitoring signal _{i T,} which will be described later. That is, in order to each of the analog filter 2 _-1 and _2-2 system current i _L, it is the system voltage v and the monitoring signal i _T inputted superimposed.

The outputs of the analog filters 2 _-1 and 2 _-2 are sampled and held at a predetermined sampling period by sample hold circuits (S / H) 3 _-1 and 3 _-2 , respectively. Multiplexer (MPX) 4 sample and hold circuit (S / _{H) 3 -1} and ₃ sequentially switching the output _-2 and outputs rearranged in time series, an analog-to-digital converter (hereinafter, an A / D converter (Abbreviated) 5 converts the sample hold value input in time series into a digital quantity.

  Thus, the data converted into the digital value by the analog input circuit 20 is temporarily stored in the random access memory (RAM) 6 and stored in advance in the read-only memory (ROM) 7 according to the arithmetic program. (CPU) 8 is used for protection calculation and calculation for analog filter monitoring.

  In addition to the components and means described above, a digital input / output means is required to configure the digital protection / control device, but it is not directly related to the analog filter monitoring method that is the object of the present invention. Detailed description thereof will be omitted.

9 is a monitoring signal generating circuit, and inputs a monitoring signal i _T generated in the analog filter 2 _-1 and _2-2. Incidentally, monitoring signal generating circuit 9 is composed of the generation timing of the monitoring signal i _T in synchronization with the conversion timing signal generator 10 of the A / D converter 5.

11 is a reference signal generator, configured to generate a reference signal 14 that is synchronized with the monitoring signal i _T from the monitor signal generating circuit 9, directly reference signal 14 generated without passing through the analog filter 2 The signal is input to the sample hold circuit 3- _T and sampled and held. The data sampled and held here is input to the A / D converter 5 through the multiplexer 4 and is output as digital signal reference signal data 14 to be described later. A series of circuits for converting the reference signal 14 composed of the reference signal generator 11, the sample hold circuit 3- _T , the multiplexer 4 and the A / D converter 5 into a digital value is referred to as a reference signal digital data acquisition means.

Next, the monitoring / relay calculation signal output means 30 will be described with reference to FIG. The monitoring / relay calculation signal output means 30 is executed by software processing.
The software processing in FIG. 2 is realized by using the RAM 6, ROM 7 and CPU 8 shown in FIG. 1, and both the input data (i _L + i _T ) 12 and the reference signal data 14 are A / D in FIG. Data output from the converter 5. Among these, the input data (i _L + i _T ) 12 is the system current i _L superimposed on the analog filter 2 (indicated as 2 when it is not necessary to distinguish between 2 ₋₁ and 2 ₋₂ ). And the monitoring signal i _T are converted into digital data and introduced into the storage circuit 13 and the subtractor 18.

  On the other hand, the reference signal data 14 is data obtained by converting the reference signal output from the reference signal generator 11 into digital data by the A / D converter 5 in FIG. 1 and is input to the reference signal phase detection circuit 15. The The reference signal phase detection circuit 15 is configured to output a timing signal at a specific timing of the input reference signal data. The specific timing is, for example, a zero cross point at which the data sign changes.

The storage circuit 13 starts from the output of the timing signal of the reference signal phase detection circuit 15 when the storage command 16 is established when the system current i _L is zero, and only the monitoring signal i _T is continuously generated for a predetermined period. The input data is stored in time series. That is, the input data for only monitoring signal i _T, is for storing in advance before production in the memory circuit 13.

The storage data selection circuit 17 selects data having the same phase as the monitoring signal i _T from the time-series storage data of the storage circuit 13 based on the time point when the timing signal of the reference signal phase detection circuit 15 is input. Output to the subtractor 18.

FIG. 3 is a waveform diagram for easily explaining the monitoring / relay calculation common signal output means 30 described above.
In the example of FIG. 3, the monitoring signal i _{T is set} to a quadruple harmonic with respect to the system current i _L and the reference signal 14 is generated at the zero cross point of the monitoring signal i _T.

Reference signal 14 is the same cycle as the monitoring signal i _T, from the memory circuit 13 which stores waveform data sequence of the monitoring signal i _T, the data to be subtracted by the subtractor 18 is selected from the stored data selection circuit 17 Use as a reference timing for

When the analog filter is in a normal state, the monitoring signal i _T has a solid waveform, and when the monitoring signal waveform data stored in the storage circuit 13 is subtracted from the input data 12 by the subtractor 18, i is output as output data. _{Get L.}

When the analog filter is in an abnormal state, for example, the phase shifts as shown by a broken line, or the amplitude value changes as shown by a one-dot chain line, so that the monitor signal waveform data stored in the storage circuit 13 from the input data 12 is subtracted. subtracting 18, the output data obtained by adding the remaining components of the monitoring signal i _T a i _L is obtained.

As described above, the monitoring / relay calculation common signal output means 30 has the subtractor 18 input data (i _L + i _T ) 12 in a normal state where the monitoring signal i _T is superimposed on the system current i _L. By subtracting the storage input data of the storage circuit 13 selected by the storage data selection circuit 17 from the common signal (hereinafter referred to as monitoring / relay calculation) that combines the monitoring signal of the analog filter 2 and the relay calculation signal. 19 (abbreviated as a signal for use).
The monitoring / relay calculation signal 19 output from the monitoring / relay calculation common signal output means 30 is input to the analog filter monitoring means of FIG. 4 and monitored.

The analog filter monitoring means 40 in FIG. 4 is also realized by using the RAM 6, the ROM 7 and the CPU 8, and here, one channel is shown.
The analog filter monitoring means 40 receives the monitoring / relay calculation signal 19 output from the subtractor 18 of FIG. 3 and inputs a digital filter processing means 41 for calculating a monitoring signal extraction process, and this digital filter processing means 41. The amplitude value calculation processing means 42 for calculating the amplitude value by inputting the monitoring signal output from the signal, and the amplitude value of the monitoring signal output from the amplitude value calculation processing means 32 are input, and this amplitude value is preset. The comparison processing means 43 detects whether the relative error is within the allowable error range (K) by comparing with the theoretical value (set value) of the monitoring signal.

The digital filter processing means 41 can apply a non-recursive filter having a simple configuration as described in Patent Document 1. When the monitoring signal is a quadruple harmonic with respect to the fundamental wave, the digital filter processing means 41 applies the following equation (1) in order to extract the monitoring signal of the fourth harmonic.
_{y m = x m + x m} -3 + x m-6 + x m-9 ... (1)
Here, x _mn represents sampling data for every 30 ° of electrical angle of the fundamental wave, and _n means past data before n sampling.
The digital filter processing means may have a configuration other than the above acyclic type.

  In FIG. 4, the digital filter processing means 41 extracts a monitoring signal from the monitoring / relay calculation signal 19 input from the monitoring / relay calculation common signal output means 30 of FIG. Output. The amplitude value calculation processing means 42 calculates the amplitude value of the monitoring signal for each channel. The comparison processing means 43 inspects whether or not the amplitude value is within a preset allowable error range (K1) of the monitoring signal, and outputs the inspection result as the monitoring result 45. If the monitoring result 45 exceeds the permissible error range (K1), a failure is indicated on a display panel of an interface (not shown) and the digital protection or control calculation is locked.

(Function)
According to the present invention, the monitoring signal i _T contained in the input data _(i L ₊ i T) ₁₂ of superimposed Figure 2 from the monitor signal generating circuit 9 of FIG. 1 is stored as the memory circuit 13 time-series data stored The subtractor 18 subtracts from the input data (i _L + i _T ) 12. Therefore, if there is no failure in the analog filter _2-1 or _2-2 , the monitoring / relay calculation signal 19 is represented by the electric quantity data (i _L ), and the amplitude value of the monitoring signal calculated by the amplitude value calculation processing means 42 in FIG. 4 becomes almost zero.

However, if there is a failure in the analog filter _2-1 or _2-2 , the input data (i _L + i _T ) 12 in FIG. 2 changes in size and phase, and is included in the input data (i _L + i _T ) 12. Since the monitoring signal i _T to be recorded is different from the time-series storage data recorded in the storage circuit 13, the monitoring signal other than the electric quantity data (i _L ) remains in the subtraction result of the subtracter 18. For this reason, the amplitude value of the monitoring signal calculated by the amplitude value calculation processing means 42 of FIG. 4 does not become zero. Therefore, it is possible to detect a failure of the analog filter 2 by monitoring the amplitude value of the monitoring signal.

(effect)
As described above, in the conventional monitoring method, it is necessary to monitor two types of data, that is, monitoring data and relay calculation data. However, according to the present embodiment, the monitoring data and the relay calculation data are shared. Thus, the failure of the analog filter can be detected by monitoring one type of data. Further, according to the present embodiment, it is not necessary to compare with other channels, and it is possible to identify a defective channel with a simple process, thereby reducing the processing load for calculating data and the memory consumption. Is possible.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS.
FIG. 5 is a block diagram depicting a digital protection / control device according to the second embodiment of the present invention, paying attention to an analog input circuit, and FIG. 6 is a monitoring and relay operation performed by the digital protection / control device of the present invention. It is a block diagram which shows a signal output means.

  FIGS. 5 and 6 are diagrams corresponding to FIGS. 1 and 2 of the first embodiment, respectively. The same parts are denoted by the same reference numerals, and the corresponding parts are denoted by the subscript A. Omitted as appropriate.

  In FIG. 5, reference numeral 20 </ b> A denotes an analog input circuit, which is different from the first embodiment in the configuration for inputting a monitoring signal to the analog filter 2. That is, 51 is a monitoring signal input command, which is controlled by software, and is configured to input the signal of the monitoring signal generation circuit 9 to the analog filter 2 when this command is established. When the input command 51 is established, the application control circuit 52 is a circuit that performs control so that the monitoring signal is always input for a certain period at the same phase timing. The application control circuit 52 can be easily configured, for example, by starting a one-shot timer at the timing when the monitoring signal changes from negative to positive and applying the monitoring signal during the output period of the timer.

Next, the monitoring and relay calculation signal output means 30A will be described with reference to FIG. The monitoring / relay calculation signal output means 30A is executed by software processing.
The software processing in FIG. 6 is implemented using the RAM 6, ROM 7 and CPU 8 shown in FIG. The monitoring / relay calculation common signal output means 30A of the present embodiment is different from the first embodiment in the way of generating timing signals to be supplied to the storage circuit 13 and the storage data selection circuit 17. That is, in FIG. 6, when the storage command 16 is established, the input data of only the monitoring signal component when the system electrical quantity i _L is zero is stored in time series in the storage circuit 13 from the timing of the input command 51. Constitute.

The constant of the condition being operated protective relays, holds, the input command, the input data 12 is monitoring signal i _T lineage electrical quantities i _L is superimposed, this time, the establishment timing of the input command 51 At the starting point, the time series storage data of the storage circuit 13 is sequentially selected by the storage data selection circuit 17 and subtracted from the input data 12 by the subtractor 18, and this output is used for monitoring and relay calculation.
Also in this embodiment, the analog filter monitoring means corresponding to FIG. 4 in the first embodiment is necessary, but since this means is the same, the drawing is omitted in this embodiment.

  In the present embodiment, both the stored data and the input data are response data to the same monitoring signal input starting from the timing at which the input command is established, and therefore are included in the input data 12 based on the timing at which the input command is established. By subtracting the time-series storage data having the same phase as the instantaneous value data of the monitoring signal component by the subtracter 18, it is possible to selectively cancel only the monitoring signal component from the data used for the protective relay operation. become.

  As described above, also in this embodiment, the same effect as that of the first embodiment can be obtained, and a highly accurate analog input circuit monitoring method that can be applied to either continuous monitoring or automatic inspection can be realized.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS.
FIG. 7 is a block diagram illustrating a digital protection / control device according to a third embodiment of the present invention, paying attention to an analog input circuit. FIG. 8 is a monitoring / relay operation signal by the digital protection / control device of the present invention. FIG. 9 is a block diagram showing the output means, and FIG. 9 is a waveform diagram for explaining the timing control method.

  FIGS. 7 and 8 are diagrams corresponding to FIGS. 5 and 6 of the second embodiment, respectively. The same parts are denoted by the same reference numerals, and the corresponding parts are denoted by the subscript B. Omitted as appropriate.

This embodiment is different from the first embodiment and the second embodiment in the timing of superimposing and subtracting the monitoring signal. That is, in the present embodiment, a sampling number counting circuit 53 that sequentially counts the sampling number of the sampling signal corresponding to the timing signal output from the conversion timing signal generator 10 of the A / D converter 5 is newly provided. By inputting the sampling number 54 output from the number count circuit 53 to the application control circuit 52, the storage circuit 13 and the storage data selection circuit 17, the monitoring signal i _T to the system electric quantity i _L in the analog filter 2 is obtained. it is obtained so as to control subtraction timing of the monitoring signal i _T with superimposed timing and monitoring relay operation for the common signal output unit 20B.

Next, a timing control method for superimposing and subtracting the monitoring signal will be described with reference to FIG.
Since the A / D converter 5 samples 96 cycles of one cycle of the fundamental wave (system frequency) with a sampling signal corresponding to the timing signal output from the conversion timing signal generator 10, the monitoring signal is a quadruple harmonic. One cycle is sampled 24 times.

  For this reason, a sampling number is assigned to the sampling signal from 0 to 23, and when this number is 0, the monitoring signal is started to be superimposed on the system electricity quantity. As a result, the digital data of the monitoring signal corresponding to each sampling number is stored in the storage circuit 13. The storage data selection means 17 receives the sampling number output from the sampling number counting means and outputs the storage data stored in the storage time means 13.

If the data output from the stored data selection means 17 is subtracted from the input signal (i _L + i _T ) 12 by the subtractor 18, the monitoring / relay calculation signal 19 can be obtained. In the normal state, the monitoring / relay calculation signal 19 is i _L , but if the analog filter 2 is faulty, a part of the monitoring signal component remains in i _L , so the analog filter connected to the next stage Monitoring is performed by the monitoring circuit 40.
According to the present embodiment, it is possible to realize an analog circuit monitoring method that is simpler in configuration and software processing than the first and second embodiments.

1 is a configuration diagram depicting a digital protection / control device according to a first embodiment of the present invention, paying attention to an analog input circuit. The block diagram which shows the signal extraction means for the monitoring by the digital protection and control apparatus which concerns on the 1st Embodiment of this invention, and protection and control calculation. The wave form diagram for demonstrating the common signal output means for monitoring and relay calculation. The block diagram which shows the analog filter monitoring means by the digital protection and control apparatus of this invention. The block diagram which drew the digital protection and control apparatus which concerns on the 2nd Embodiment of this invention paying attention to an analog input circuit. The block diagram which shows the signal extraction means for the monitoring by the digital protection and control apparatus which concerns on the 2nd Embodiment of this invention, and protection and control calculation. The block diagram which drew the digital protection and control apparatus which concerns on the 3rd Embodiment of this invention paying attention to an analog input circuit. The block diagram which shows the signal output means for monitoring and relay calculation by the digital protection and control apparatus of this invention. The wave form diagram for demonstrating the timing control method which superimposes and subtracts the monitoring signal.

Explanation of symbols

1 ... input _{transducer, 2} -1, 2 _{-2 ...} analog _filter, 3 _{-1, 3} -2, 3 _{-T ...} sample and hold circuit (S / H), 4 ... multiplexer (MPX), 5 ... analog-to-digital Converter (A / D converter), 6 ... Random access memory (RAM), 7 ... Read only memory (ROM), 8 ... Digital arithmetic unit (CPU), 9 ... Monitoring signal generation circuit, 10 ... Transmitter, DESCRIPTION OF SYMBOLS 11 ... Reference signal generator, 12 ... Input data, 13 ... Storage circuit, 14 ... Reference signal data, 15 ... Reference signal phase detection circuit, 16 ... Storage command, 17 ... Storage data selection circuit, 18 ... Subtractor, 19 ... Monitoring / relay operation signal, 20, 20A, 20B ... analog input circuit, 30, 30A, 30B ... monitoring / relay operation common signal output means, 40 ... analog filter monitoring means, 41 ... digital filter processing, 42 ... amplitude value calculation processing means, 43 ... comparison processing means, 44 ... monitoring result, 51 ... input command, 52 ... application control circuit, 53 ... sampling number counting circuit, 54 ... sampling number.

Claims (3)

The system electricity quantity taken from the power system is introduced into an analog filter and converted into digital data, and a monitoring signal having a predetermined frequency and a predetermined magnitude is superimposed on the system electricity quantity and input to the analog filter. In the monitoring system of the digital protection / control device that monitors the analog input circuit using the output signal of the analog input circuit,
Monitoring signal generating means for generating a monitoring signal synchronized with a timing signal of analog-digital conversion;
Sampling number counting means for sequentially counting the sampling number of the sampling signal distributed over one period of the monitoring signal when the monitoring signal is sampled with a sampling signal corresponding to the timing signal of the analog / digital conversion;
Application control means for starting to superimpose the monitoring signal on the grid electricity quantity when the sampling number counting means has a predetermined sampling number;
Storage means for storing digital data of the monitoring signal corresponding to a sampling number after the superimposition start of the monitoring signal for a predetermined period;
Storage data selection means for receiving the sampling number output from the sampling number counting means and selecting the storage data of the storage circuit means;
Subtracting means for subtracting the output of the storage data selection means from the digital data when a monitoring signal is superimposed on the grid electricity quantity, and outputting data for monitoring and protection operation;
An analog filter that extracts a monitoring signal from the data for monitoring and protection calculation, detects whether the size of the extracted monitoring signal is within a predetermined tolerance, and determines whether there is a failure in the analog filter And a monitoring means for the digital protection / control device. The analog filter monitoring means monitoring system of claim 1 Symbol placement digital protection and control device characterized by having a digital filter processing means for extracting a monitor signal from the data for the monitoring and protection operation. The analog filter monitoring means monitoring system of claim 1 Symbol placement digital protection and control device characterized by having an amplitude value calculation processing means for calculating the amplitude value of the extracted supervisory signal.

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