JPS61114759A - Method for detecting spark discharge of electric precipitator - Google Patents

Abstract

PURPOSE:To make it possible to stably operate an electric precipitator with high efficiency, by calculating a voltage estimation value from a voltage value obtained by sampling at a constant cycle and comparing this value with an actual sampling value to detect the generation of spark discharge. CONSTITUTION:A high voltage DC current is supplied to an electric precipitator 2 (hereinbelow mentioned as EP) from a power source apparatus 1. The voltage signal 3 of EP2 is received by the spark discharge detection circuit 5 in a power source control apparatus 4 and the detection signal 6 thereof is outputted when spark discharge is generated. That is, the present value V of the voltage signal 3 is sampled at a constant cycle and compared with the estimation value V' calculated and stored at the previous sampling time and, if V'-V is larger than a reference value VD, spark discharge is considered to be generated to issue the detection signal 6. Whereupon a control circuit 7 receives said signal 6 to perform necessary control operation and the power source apparatus 1 is connected by a control signal 8.

Description

[Detailed Description of the Invention] [Industrial Application Field] In order to operate an electrostatic precipitator (hereinafter abbreviated as EP) stably and with high efficiency, the present invention automatically and reliably eliminates spark discharge generated in the EP. The present invention relates to a method for detecting spark discharge of EP.

[Conventional technology]

Generally, as shown in FIG. 5, the voltage waveform before and after the spark discharge of EP occurs, in a state where no spark discharge occurs, 1 voltage becomes a pulsating flow with an average of ++t VM.

The frequency of this pulsating current is, for example, 2 fHz when the fH2 AC power source is full-wave rectified and applied to GP. When a spark discharge occurs, the voltage drops significantly as shown in (■).

A conventional spark discharge detection method in a digital control device using a microcomputer or the like will be explained with reference to FIG. The control device samples the voltage signal at a certain period to obtain the current value V of the voltage. Next, it is checked whether this value (■) is smaller than a predetermined reference value v8, and if it is, it is assumed that a spark discharge has occurred, a spark discharge detection method is issued, and the process is executed to proceed to the subsequent process. ing.

[Problem that the invention seeks to solve]

In the conventional example above, if the reference value vs is set too low, if the operating voltage of the EP is high, that is, the VM in FIG.
In a section where the voltage is high, even if a spark discharge occurs, the voltage may not fall below the reference value v8, and in this case, the guard cannot detect the occurrence of the spark discharge. On the other hand, if the reference value Vs is increased, the trough of the pulsating flow may become less than the reference value Vs if the operating voltage is low and the ripple of the pulsating flow is large, resulting in erroneous detection. Furthermore, the operating voltage and pulsating current ripple values are
The reference value Vs differs depending on the EP, and it takes time and effort to set the reference value Vs for each EP by looking at the driving situation. Also in the same EP,
Since the voltage and ripple change from moment to moment depending on the load condition, etc., there is a problem that there are many cases of failure to detect the occurrence of spark discharge or false detection.

In general, the frequency of spark discharge occurrence is closely related to dust collection efficiency, and since spark discharge is a sign of continuous abnormal discharge such as glow discharge and arc discharge, it is necessary to operate EP stably and with high efficiency. In order to control the spark discharge, a new method is required to reliably detect the occurrence of spark discharge regardless of the characteristics of the IP and the operating conditions. It is an object of the present invention to provide an EP spark discharge detection method that can solve the above-mentioned conventional problems.

[Means for solving problems]

The EP spark discharge detection method according to the present invention samples the precipitator voltage at regular intervals in the IP, and always uses the latest n
The predicted voltage value is calculated from the n sampled values, the predicted voltage value of O is compared with the actual sampled value, and when the difference is greater than the reference value, spark discharge is detected. It is characterized by being considered.

[Effect]

According to the present invention, when no spark discharge occurs, the actual I
Calculate the predicted value that the current sampling value of the M-unit pressure should be this value using the past sampling gain, and then compare the actual sampling value with the above predicted value. , when the difference is larger than the reference value, it is assumed that a spark discharge has occurred, and the occurrence of spark discharge of the EP can be reliably detected without being influenced by the operation of F and P or the ripple value. In this way, the above-mentioned conventional problems can be solved.

〔Example〕

An embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Figure @1 is a block diagram showing the configuration of an embodiment of the device used to carry out the method of the present invention, in which 1 is a power supply device, 2 is an EP, 3 is a voltage signal of the EP, 4 is a power supply control device, and 5 is a power supply device. 1 is a spark discharge detection circuit, 6 is a detection signal, 7 is a control circuit, and 8 is a control signal.

As shown in FIG. 1, the power supply I! A high voltage direct current is supplied from tI to EP2. A voltage signal 3 of EP2 is received by a spark discharge detection circuit 5 in a power supply control device 4, and a detection signal 6 is output when a spark discharge occurs. Upon receiving the detection signal 6, the control circuit 7 performs a necessary μs control operation (for example, turns off the power for a very short period of time), and controls the power supply device l using the control signal 8.

Fig. 2 shows the sampling time t and sample value V of the voltage signal of the example shown in Fig. Indicates the condition that has occurred.

The operation of the above embodiment of the present invention will be explained.

When the sampling time comes at 2 in FIG. 3, the current value V of the voltage signal is obtained. Next, compare this habit with the predicted value V' that was calculated at the previous sampling time and stored in memory, and y
If -v is larger than a predetermined base value vD, it is assumed that a spark discharge has occurred, and a spark discharge detection circuit is activated. V/
If V is smaller than VD, the current value V is first stored, assuming that no sparks have occurred. At this time, the stored contents are updated so that the most recent sampling shift of n points in the past, including the current first shift V, is always stored. Next, the next sample value is prepared using these n 1 shifts.
1ft1. l l[ is calculated and stored in preparation for the next sampling. For example, a detailed explanation of how to calculate a predicted value using voltage values from three past points will be provided by two people and two figures. If the current sampling time is t3, at this point, the past three sample voltage values vl + v2 r V3 are stored, so "4" 3 "s -3V2 + V,
...... (1) is set as the needle wheel, and this Vl is set as the sample shift 1 prediction (IQ 41i) at the next sampling time.

Figure 2 (here, ■+ + vz * Vs + v4
[C] Since this is time series data taken at regular intervals of 1 kilometer, if you calculate the differences up to the third floor with respect to time, you will get something like the table in Figure 4. In general, the difference value of time-series data obtained by sampling a signal that fluctuates smoothly over time is different from the state of the BP voltage when no spark discharge occurs. becomes smaller. In the case of BP, the frequency of the voltage ripple is 2fHz, and the sampling period is about 2ΔfHz. In this case, if the difference is calculated up to the third floor, the value will be sufficiently smaller than the absolute value of the voltage.

Therefore, in Figure 4, it can be considered that ΔwQ, and Va
-3V3 3 V@ + v+, and the known V, , V2. at time ts. From V, the preview 11 value y7, which would be this value at time t4 if no spark discharge occurs, can be calculated according to equation (1). At time t4, when the actual sample ([v4 is obtained, v4'-■4 is calculated, and if this value is greater than or equal to the reference value VD, it is said that the voltage value has suddenly decreased, and the occurrence of spark discharge is detected. Can be detected.

This method focuses on relative changes in voltage, and is independent from the absolute value of voltage, so it can be used reliably without being affected by the EP operating voltage, ripple size, etc. Can detect human flower release.

〔Effect of the invention〕

According to the method of the present invention, the following excellent effects can be achieved.

(It is affected by the characteristics of IIIP, operating pressure, voltage waveform, etc. 1j<1, spark discharge can be detected reliably.

(2) Only the time-series data of the past n points are used to calculate the first prediction using simple arithmetic operations, resulting in a simple and inexpensive configuration.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of an apparatus used to carry out the method of the present invention, and FIGS. 1A and 1B are diagrams for explaining conventional examples. ! ...Power supply device, 2...EP, 3...Voltage signal,
4... Power supply control device, 5... Spark discharge detection circuit, 6
. . . detection signal, 7 . . . control circuit, 8 . . . control signal.

Claims (1)

[Claims] In an electrostatic precipitator, the precipitator voltage is sampled at regular intervals, the latest n sampling values are always stored, a voltage prediction value is calculated from the n sampling values, and this voltage prediction value is compared with the actual voltage value. A spark discharge detection method for an electrostatic precipitator, characterized in that a sampled value is compared with a sample value, and when the difference between the two values is larger than a reference value, it is determined that a spark discharge has occurred.