CN109460006B - Method for detecting oscillation of control system - Google Patents
Method for detecting oscillation of control system Download PDFInfo
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- CN109460006B CN109460006B CN201811326384.0A CN201811326384A CN109460006B CN 109460006 B CN109460006 B CN 109460006B CN 201811326384 A CN201811326384 A CN 201811326384A CN 109460006 B CN109460006 B CN 109460006B
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B23/00—Testing or monitoring of control systems or parts thereof
- G05B23/02—Electric testing or monitoring
- G05B23/0205—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults
- G05B23/0208—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults characterized by the configuration of the monitoring system
- G05B23/0213—Modular or universal configuration of the monitoring system, e.g. monitoring system having modules that may be combined to build monitoring program; monitoring system that can be applied to legacy systems; adaptable monitoring system; using different communication protocols
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/20—Pc systems
- G05B2219/24—Pc safety
- G05B2219/24065—Real time diagnostics
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Abstract
A method of controlling detection of system oscillations, comprising the steps of: s1, arranging an oscillation detection device at a key station where oscillation is likely to occur in the control system; s2, arranging a voltage and current detection device and a wireless signal transmission device connected with the voltage and current detection device and the oscillation detection device on a line connected with the key station; and S3, carrying out oscillation detection on the key station by using the oscillation detection device, carrying out real-time acquisition on the three-phase current and the three-phase voltage of a line connected with the key station by using the voltage and current detection device, and recording the detected real-time oscillation data, the detected three-phase current data and the detected three-phase voltage data. The invention effectively overcomes the problem that the deviation between the set value and the field actual value cannot reach the threshold value.
Description
Technical Field
The invention relates to the technical field of automatic control, in particular to a method for detecting oscillation of a control system.
Background
An automatic regulating system, namely a classical PID regulating system which is used most at present, can work stably and reliably at the initial stage of commissioning, but due to the change of the characteristics of a controlled object, the lack of the maintenance of a system or equipment, accidental large-amplitude external disturbance factors and the like, the control system is likely to work abnormally, the stability margin of the system is reduced, and even the oscillation of technological process parameters occurs. Abnormal conditions of these control systems may cause process parameters to fail to meet the requirements of the process, resulting in a degradation of product quality; it is also possible to damage the control device itself. The system is not beneficial to safe and stable operation.
The traditional solution is to switch to manual operation when the deviation between the set value and the PV value on site exceeds a certain limit. The manual switching mode is single in judgment mode, and meanwhile, the self deviation of the set value and the PV value is large under some special conditions, and manual switching is not needed at the moment, so that the threshold value of the deviation of the set value and the field actual value is large, oscillation occurs in a control loop, particularly a controlled object with large pure delay often shows low-frequency constant-amplitude oscillation, and when the deviation does not reach the threshold value, the system cannot be switched manually, so that the oscillation lasts for a long time.
Disclosure of Invention
The invention aims to overcome the defects and shortcomings of the prior art and provide a method for detecting the oscillation of a control system, which aims at the situation that a controlled object with large pure delay of a power system often shows low-frequency constant-amplitude oscillation, but when the deviation does not reach a threshold value, the system cannot be manually operated so that the oscillation can be continued for a long time; sampling is carried out by extracting the deviation of a set value and a field value, sampling signals are grouped according to frequency, the energy mean square sum of different frequency bands in a period of time and the energy ratio of adjacent frequency bands are respectively calculated, whether the system oscillates is judged according to the threshold value of the energy ratio of the adjacent frequency bands, and the problem that the deviation of the set value and the field actual value cannot reach the threshold value is effectively solved.
The technical scheme adopted by the invention for solving the problems is as follows:
a method of controlling detection of system oscillations, comprising the steps of:
s1, arranging an oscillation detection device at a key station where oscillation is likely to occur in the control system;
s2, arranging a voltage and current detection device and a wireless signal transmission device connected with the voltage and current detection device and the oscillation detection device on a line connected with the key station;
s3, carrying out oscillation detection on the key station by using the oscillation detection device, carrying out real-time acquisition on three-phase current and three-phase voltage of a line connected with the key station by using the voltage and current detection device, and recording detected real-time oscillation data, three-phase current data and three-phase voltage data;
s4, the wireless signal transmission device sends the real-time oscillation data, the three-phase current data and the three-phase voltage data to a system detection center;
wherein, the step that the oscillation detection device carries out oscillation detection includes:
s101, extracting the deviation between a set value and a field actual value in a control system for sampling;
s102, grouping the sampling signals according to the frequency;
s103, respectively calculating the energy mean square sum of different frequency bands in a period of time and the energy mean square sum ratio of adjacent frequency bands;
and S104, judging whether the system oscillates or not according to the threshold value of the energy mean square sum ratio of the adjacent frequency bands.
Further, the oscillation detection device comprises one or more of a multi-frequency oscillation monitoring device, a low-frequency constant amplitude oscillation monitoring device, a self-excited coupling oscillation monitoring device or a PMU phasor measurement unit.
Further, the oscillation detection device and the voltage and current detection device are started simultaneously, and a starting time t1 is recorded when the oscillation detection device and the voltage and current detection device are started, the oscillation time is represented by t2, and then the starting time t1 and the oscillation time t2 are also sent to a system detection center through the wireless signal transmission device.
Further, in step S102, the grouping includes the following specific steps: firstly, grouping the sampling signals according to the frequency, and then filtering the sampling signals in a high-pass mode, a low-pass mode and a band-pass mode respectively.
Further, the data transmitted to the system detection center by the wireless signal transmission device comprises the instantaneous value and the effective value of the electric quantity with time scales, the amplitude and the phase of the electric quantity component of a plurality of characteristic frequencies, the starting time t1 and the oscillation time t2, and real-time oscillation data of the control system.
In conclusion, the beneficial effects of the invention are as follows:
the invention samples by extracting the deviation of the set value and the field value, groups the sampling signals according to the frequency, respectively calculates the energy mean square sum of different frequency bands in a period of time and the energy ratio of adjacent frequency bands, and respectively judges whether the system oscillates according to the threshold value of the energy ratio of the adjacent frequency bands, thereby effectively overcoming the problem that the deviation of the set value and the field actual value cannot reach the threshold value.
Drawings
Fig. 1 is a schematic diagram of the logic control of the filter in embodiment 1 of the present invention.
FIG. 2 is a schematic diagram of the logic operation of step S103 according to the present invention.
Fig. 3 is a schematic diagram of an original signal and a frequency packet signal in embodiment 2 of the present invention.
Fig. 4 is a simplified process diagram of the control system after oscillation is detected in accordance with the present invention.
Detailed Description
In order to solve the problem that in the prior art, a controlled object with a large pure delay of a power system often shows low-frequency constant-amplitude oscillation, but when the deviation does not reach a threshold value, the system cannot be manually operated so that the oscillation can be continued for a long time. The present invention will be described in further detail with reference to the following examples and accompanying drawings, but the embodiments of the present invention are not limited thereto, and the drawings are only an example of the application of the present invention and do not essentially restrict the principle of the present invention.
Example 1:
referring to fig. 1 and 2, a method of controlling system oscillation detection;
a method of controlling detection of system oscillations, comprising the steps of:
s1, arranging an oscillation detection device at a key station where oscillation is likely to occur in the control system;
s2, arranging a voltage and current detection device and a wireless signal transmission device connected with the voltage and current detection device and the oscillation detection device on a line connected with the key station;
s3, carrying out oscillation detection on the key station by using the oscillation detection device, carrying out real-time acquisition on three-phase current and three-phase voltage of a line connected with the key station by using the voltage and current detection device, and recording detected real-time oscillation data, three-phase current data and three-phase voltage data;
s4, the wireless signal transmission device sends the real-time oscillation data, the three-phase current data and the three-phase voltage data to a system detection center;
wherein, the step that the oscillation detection device carries out oscillation detection includes:
s101, extracting the deviation between a set value and a field actual value in a control system for sampling;
s102, grouping the sampling signals according to the frequency;
s103, respectively calculating the energy mean square sum of different frequency bands in a period of time and the energy mean square sum ratio of adjacent frequency bands;
and S104, judging whether the system oscillates or not according to the threshold value of the energy mean square sum ratio of the adjacent frequency bands.
Further, the oscillation detection device comprises one or more of a multi-frequency oscillation monitoring device, a low-frequency constant amplitude oscillation monitoring device, a self-excited coupling oscillation monitoring device or a PMU phasor measurement unit.
Further, the oscillation detection device and the voltage and current detection device are started simultaneously, and a starting time t1 is recorded when the oscillation detection device and the voltage and current detection device are started, the oscillation time is represented by t2, and then the starting time t1 and the oscillation time t2 are also sent to a system detection center through the wireless signal transmission device.
Further, in step S102, the grouping includes the following specific steps: firstly, grouping sampling signals according to the frequency, and then filtering the sampling signals in a high-pass mode, a low-pass mode and a band-pass mode respectively; the filtering algorithm refers to a well-established filtering method, such as chebyshev filter, butterworth filter, etc. The higher the order of the filter is, the better the filtering effect is, but the larger the corresponding calculation amount is; regarding the relative configuration of the low-pass filter and the high-pass filter, it needs to be determined analytically according to the response speed of the controlled object.
Further, the data transmitted to the system detection center by the wireless signal transmission device comprises the instantaneous value and the effective value of the electric quantity with time scales, the amplitude and the phase of the electric quantity component of a plurality of characteristic frequencies, the starting time t1 and the oscillation time t2, and real-time oscillation data of the control system.
Example 2:
on the basis of the above-described embodiment 1, as shown in fig. 3 and 4,
a method of controlling detection of system oscillations, comprising the steps of:
s1, arranging an oscillation detection device at a key station where oscillation is likely to occur in the control system;
s2, arranging a voltage and current detection device and a wireless signal transmission device connected with the voltage and current detection device and the oscillation detection device on a line connected with the key station;
s3, carrying out oscillation detection on the key station by using the oscillation detection device, carrying out real-time acquisition on three-phase current and three-phase voltage of a line connected with the key station by using the voltage and current detection device, and recording detected real-time oscillation data, three-phase current data and three-phase voltage data;
s4, the wireless signal transmission device sends the real-time oscillation data, the three-phase current data and the three-phase voltage data to a system detection center;
wherein, the step that the oscillation detection device carries out oscillation detection includes: firstly, collecting an original signal as shown in a first group of signals in figure 1, wherein the signal is the deviation between a set value and an actual value;
secondly, dividing the signal into 5 groups according to the frequency, and setting half of the sampling frequency as Fa, then dividing five groups into frequency ranges of [0, Fa/16], [ Fa/16, 2 Fa/16], [2 Fa/16, 4 Fa/16], [4 Fa/16, 8 Fa/16], [8 Fa/16, inf ], wherein the first filter is a low-pass filter, the cut-off frequency is Fa/16, the last filter is a high-pass filter, the cut-off frequency is 8 Fa/16, and the rest are band-pass filters; for example, using a butterworth filter, the normalized transfer function of its low-pass filter is:
wherein Ω c is the cut-off frequency Fa/16, skRelevant parameters for filter design. The remaining band pass filters are similar to the high pass filter;
the data grouped by frequency are shown as data of respective frequency bands in fig. 1;
thirdly, respectively calculating the energy (mean square sum) of each frequency band and the energy ratio of adjacent frequency bands;
and fourthly, respectively judging whether the system oscillates according to the threshold value.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may be made by those skilled in the art without departing from the principle of the invention.
Claims (5)
1. A method of controlling system oscillation detection, comprising the steps of:
s1, arranging an oscillation detection device at a key station where oscillation is likely to occur in the control system;
s2, arranging a voltage and current detection device and a wireless signal transmission device connected with the voltage and current detection device and the oscillation detection device on a line connected with the key station;
s3, carrying out oscillation detection on the key station by using the oscillation detection device, carrying out real-time acquisition on three-phase current and three-phase voltage of a line connected with the key station by using the voltage and current detection device, and recording detected real-time oscillation data, three-phase current data and three-phase voltage data;
s4, the wireless signal transmission device sends the real-time oscillation data, the three-phase current data and the three-phase voltage data to a system detection center;
wherein, the step that the oscillation detection device carries out oscillation detection includes:
s101, extracting the deviation between a set value and a field actual value in a control system for sampling;
s102, grouping the sampling signals according to the frequency;
s103, respectively calculating the energy mean square sum of different frequency bands in a period of time and the energy mean square sum ratio of adjacent frequency bands;
and S104, judging whether the system oscillates or not according to the threshold value of the energy mean square sum ratio of the adjacent frequency bands.
2. A method of controlling system oscillation sensing according to claim 1, wherein the oscillation sensing means comprises one or more of a multi-frequency oscillation monitoring means, a low frequency constant amplitude oscillation monitoring means, a self-coupling oscillation monitoring means or a PMU phasor measurement unit.
3. The method of claim 1, wherein the oscillation detecting device and the voltage current detecting device are activated simultaneously, and the activation time t1 is recorded when the oscillation detecting device and the voltage current detecting device are activated, and the oscillation time is represented by t2, then the activation time t1 and the oscillation time t2 are also transmitted to the system detecting center through the wireless signal transmission device.
4. The method for controlling system oscillation detection according to claim 1, wherein in step S102, the grouping comprises the following steps: firstly, grouping the sampling signals according to the frequency, and then filtering the sampling signals in a high-pass mode, a low-pass mode and a band-pass mode respectively.
5. The method of claim 1, wherein the data transmitted from the wireless signal transmission device to the system detection center comprises the instantaneous and effective values of the electrical quantity with time scales, the amplitudes and phases of the components of the electrical quantity at a plurality of characteristic frequencies, the start time t1 and the oscillation time t2, and real-time oscillation data of the control system.
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