JP2004080842A - Probe current controlled external power supply unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a probe current controlled external power supply unit which can stabilize the control by effectively attenuating AC components contained in a probe current and also can speed up the control response of a cathode corrosionproof current. <P>SOLUTION: This power unit is equipped with a power control circuit 220 which supplies a corrosionproof current via a switching-on electrode 23 and a current control circuit 230 which controls the above corrosionproof current, based on the probe current detected through a probe 24. The current control circuit 230 has a filter circuit 232 and a phase compensating circuit 238 which performs the phase compensation of the output from the filter circuit 232. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a probe current control type external power supply device and a cathode corrosion protection remote monitoring / control system including the same.
[0002]
Problems to be solved by the prior art and the invention
Conventionally, the method of controlling the cathodic protection of buried pipelines is generally performed by supplying an anticorrosion current from an external power supply through an energized electrode and controlling the ground potential using a reference electrode to clear the cathodic protection potential. Have been.
[0003]
By the way, the tube-to-ground potential is constantly fluctuated under the influence of a current flowing from a DC electric railway or a current supplied from another cathodic protection device. For this reason, a fixed potential level is set, and the set potential is compared with the measured potential. If the measured potential is higher than the set potential, the potential is decreased, and if the measured potential is lower, the potential is increased. 2. Description of the Related Art A constant potential automatic control type external power supply device that applies a voltage and controls the potential to a set potential is used.
[0004]
However, in recent years, coating and coating of pipelines have extremely excellent electrical insulation properties and extremely high coating film resistance. If there is no defect in the coating, there is no metal surface of the pipeline in contact with the external environment, it is impossible to measure the tube-to-ground potential, and it is difficult to control the output of the external power supply by the tube-to-ground potential It becomes.
[0005]
Therefore, instead of the conventional reference electrode, a probe that simulates a coating-covering defect is installed, and the output of the external power supply is controlled so that a current with an appropriate DC current density without excess or shortage flows into the probe. Proposed.
[0006]
However, since this probe current also fluctuates due to external factors as well as the tube-to-ground potential, in order to obtain the optimum anticorrosion current, set the probe inflow current and compare the set current with the measured probe current. If the current value is lower than the set current value, it is necessary to increase the anticorrosion current, and if the current value is higher, it is necessary to reduce the anticorrosion current.
[0007]
For example, in the case where a coated pipeline covered with cathodic protection is buried in the vicinity of the cross section of the DC electric railway rail, if there is a coating failure in the vicinity of the cross section of the rail, depending on the operation condition of the regenerative braking vehicle, the coating will be performed. DC current flows between the mounting defect and the electrolyte (soil). For a pipeline, when a direct current flows out of the probe in the direction of the electrolyte, it tends to corrode, and when it flows in, it tends to be anticorrosive. In addition to preventing the flow of DC current from the probe, the probe is installed near the crossing of the DC electric railway rail to avoid cathodic protection and keep the cathodic protection within an appropriate range. It is necessary to control the external power supply so that the power flows in.
[0008]
The vicinity of the garage of the DC electric railway has the following features (1) to (4).
(1) Current electric railways use regenerative braking vehicles.
(2) Rail leakage resistance is very high.
(3) Class A grounding work is performed on the wheel milling machine, bogie removal device, etc. in the train compartment, the ground resistance is as low as 10Ω or less, and electrical conduction with the rails in the train compartment is made. ing.
(4) Rail insulation and return line automatic opening / closing device are installed.
[0009]
For this reason, in the vicinity of such a garage, a pipeline having a coating with very excellent electrical insulation is buried, and when there is a coating deficiency near the garage, a load from a loader during power running is reduced. Rail leakage current flows from the coating defect portion, and this current flows from the coating defect portion near the garage in a direction in which the ground resistance of the wheel rolling machine, the bogie removal device, etc. is very low, The pipeline will corrode. In order to prevent such corrosion, the probe is electrically connected to a buried pipeline near the garage, and an external power supply is installed and controlled so that a current having an appropriate DC current density flows into the probe. It is necessary.
[0010]
In addition, at the site where the pipeline is actually buried, there is a case where a high-voltage transmission line is erected or an AC electric railway such as a Shinkansen is running so as to be parallel to or cross the pipeline. . For this reason, the buried pipeline may be subjected to AC induction, and the current flowing into the probe may be superimposed with several to several tens of AC components of the DC component. Since the probe current control controls a direct current anticorrosion current, it is necessary to separate the direct current component from the current measured through the probe (by removing the influence of the alternating current component) and provide the current to the anticorrosion current control.
[0011]
However, there are the following problems (1) to (4) in controlling the anticorrosion current by the probe current from which the influence of the AC component has been removed.
[0012]
(1) When measuring or detecting the current value, it is usual to convert the voltage using a shunt. However, when detecting the probe current, the influence on the distribution of the current density in the field is considered. In order to reduce this, the resistance of the shunt should be as small as possible. For this reason, a shunt of about 1Ω is usually used for measuring the probe current.
[0013]
However, since the probe current is controlled in the range of, for example, 0.1 to 40 mA, the current is 0.1 to 40 mV in the case of a 1Ω shunt, and a detection accuracy corresponding to the current is required. Therefore, the signal ground of the detection circuit tends to fluctuate, and higher detection accuracy is required.
[0014]
(2) The probe current in the field may include an AC component having a commercial power supply frequency (50 Hz / 60 Hz) of 70 mArms at the maximum, which is higher than the detection range of the probe current of 40 mA, so that higher detection accuracy is required.
[0015]
(3) In the probe current detection circuit, it is necessary to insert a filter that removes the AC component that is not the control target and allows only the DC component to pass. Since the constant becomes large, there is a concern that the response speed of the control is significantly reduced.
[0016]
(4) In the evaluation of the anticorrosion effect by the probe current, if the cathodic protection is not effective, the current flows from the buried pipeline to the probe, and the current flows from the probe to the ground. In such a case, it is necessary to control this outflow current so that a current of a certain current value or more flows into the probe from underground. In the evaluation of the anticorrosion effect by the probe current, the current value is managed by the average value in seconds, so it is necessary to make the rise response time of the output voltage of the power supply device that supplies the anticorrosion current to the buried pipeline as fast as possible, This is a problem of phase compensation in relation to the above (3).
[0017]
Accordingly, an object of the present invention is to provide a probe current control type external power supply capable of effectively attenuating an AC component contained in a probe current to stabilize control and to achieve a high speed control response of a cathodic protection current. It is to provide a device.
[0018]
[Means for Solving the Problems]
The present invention includes a power control circuit that supplies an anticorrosion current through a conducting electrode, and a current control circuit that controls the anticorrosion current based on a probe current detected through a probe, wherein the current control circuit includes a filter circuit, The above object has been achieved by providing a probe current control type external power supply device having a phase compensation circuit for compensating for a phase advance of an output from the filter circuit.
[0019]
Further, the present invention provides a cathode anticorrosion device having the probe current control type external power supply device of the present invention, and a terminal device which collects monitoring data from the cathodic anticorrosion device and transmits the collected monitoring data in a predetermined communication form. And a monitoring and control device that receives the monitoring data transmitted from the terminal device and remotely monitors and controls the cathodic protection device.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings.
[0021]
FIG. 1 shows an embodiment of a cathodic protection remote monitoring and control system (hereinafter, also simply referred to as a system) of the present invention. In FIG. 1, reference numeral 1 denotes a system, 10 denotes a buried pipeline serving as an anticorrosion target, 11 denotes a communication network (communication line), 12 denotes a train compartment, and 13 denotes a milling machine.
[0022]
The system 1 controls the cathodic protection device 2 to supply the anticorrosion current to the buried pipeline 10 and collects monitoring data from the cathodic protection device 2 while controlling the cathodic protection device 2. The collected monitoring data is transmitted in a predetermined communication form. A terminal device 3 for transmitting via the communication network 11, a control signal for transmitting the control signal to the terminal device 3 via the communication network 11 and receiving the monitoring data transmitted from the terminal device 3 via the communication network 11, A monitoring and control device 4 for remotely monitoring and controlling the anticorrosion device 2 is provided.
[0023]
The cathodic protection device 2 includes an energized electrode (anode terminal) 20 disposed in the ground near the buried pipeline 10, a cathode terminal 21 electrically connected to the buried pipeline 10, the energized electrode 20 and the cathode. A power supply device (probe current control type external power supply device) 22 for supplying a direct current to the terminal 21, a probe 23 connected to a shunt of a current control circuit 230 of the power supply device 22 and disposed underground, It has a terminal 24 that is short-circuited to the probe 23 via a shunt and is electrically connected to the buried pipeline 10.
[0024]
As the current-carrying electrode 20 and the cathode terminal 21, conventional ones conventionally used in this type of cathodic protection apparatus can be used without any particular limitation.
[0025]
As shown in FIG. 2, the power supply device 22 includes a power control circuit 220 that supplies an anticorrosion current through a current-carrying electrode, and a current control circuit 230 that controls the anticorrosion current based on a probe current detected through a probe 23. Have.
[0026]
The power control circuit 220 is a switching power supply circuit that rectifies and smoothes a rated AC input, converts it to a predetermined high frequency, transforms it, smoothes it, and outputs a DC current as a conduction current.
[0027]
The power control circuit 220 includes a rectifying circuit (rectifying bridge) 221 for rectifying a rated AC input, a first smoothing circuit 222 for smoothing an output from the rectifying circuit 221, and an output of the first smoothing circuit 222 at a high frequency. A switching circuit (FET) 223 for conversion, a high frequency transformation circuit 224 for transforming the AC-converted output, a high frequency rectification circuit 225 for rectifying the output of the high frequency transformation circuit 224, and a second smoothing for smoothing the rectified output. Circuit (high-frequency smoothing circuit) 226.
[0028]
The current control circuit 230 attenuates an AC component from the probe current detected by the probe 23, compares the AC component with the set current, further performs phase lead compensation, and outputs the result to the gate of the switching circuit 223. Is a circuit for controlling the output current (conduction current).
[0029]
The current control circuit 230 includes a shunt 231, a low-pass filter circuit 232, an insulation amplifier circuit 233, a detection circuit 234, a notch filter circuit 235, a current setting circuit 236, a comparison circuit 237, and a phase compensation circuit 238. , And a gate output circuit 239 to the switching circuit 223.
[0030]
It is preferable that the cutoff frequency of the low-pass filter circuit 232 is set to a predetermined value so as to minimize a delay in response speed of output control in the power supply device and to effectively use an input range of the insulating amplifier 233 described later. In the present embodiment, the cutoff frequency is set to about 15 Hz.
[0031]
It is preferable to incorporate the differential element 232a into the low-pass filter circuit 232 from the viewpoint of advancing the phase for phase advance compensation by the phase compensation circuit 238 described later while suppressing the attenuation of the high-frequency gain. In the present embodiment, a differential element of 150 Hz is incorporated in the low-pass filter circuit 232, and is provided so as to advance the phase for phase lead compensation while suppressing the attenuation of the high-frequency gain by -20 dB.
[0032]
The insulation amplification circuit 233 is inserted to separate the signal common of the detection circuit 234 from the power control circuit 220. This allows the detection circuit 234 to perform stable current detection without being affected by potential fluctuations or noise in the external environment. As the detection circuit 234, a normal current detection circuit can be used.
[0033]
The notch filter circuit 235 is a filter circuit that effectively attenuates the AC component flowing into the probe 23 due to the commercial power supply, and is preferably a band rejection type corresponding to the commercial power supply frequency (50 Hz or 60 Hz).
[0034]
It is preferable that the filter constant of the notch filter circuit 235 is set so as not to increase the Q value so that the change in the frequency characteristics of the gain and the phase becomes slow and control stability is easily obtained. In the present embodiment, the phase is gently blocked at around 50 Hz, and the phase is advanced even at around 100 Hz for phase advance compensation described later.
[0035]
It is preferable to use a phase lead compensation circuit as the phase compensation circuit 238. In the present embodiment, a differentiating circuit is added as a phase advance compensating circuit, whereby the phase is advanced near the natural frequency (200 Hz) of the second smoothing circuit 226 to secure a phase margin and control stability. Thus, the delay of the control response is reduced while suppressing the attenuation of the gain in the high-frequency region, so that both the stability of the control and the quick response are ensured.
[0036]
As the probe 23 and the terminal 24, conventional ones conventionally used in this type of cathodic protection apparatus can be used without any particular limitation.
[0037]
In addition, the cathodic protection device 2 of the present embodiment includes a relay circuit (not shown) in the power control circuit 220 so that the terminal device 3 described later can perform ON / OFF control of the output of the power supply device 22.
[0038]
The terminal device 3 includes a communication device 30 that communicates with the monitoring / control device 4 via the communication network 11, and a control / collecting unit 31 that controls the cathodic protection device 22 and collects desired monitoring data from the cathodic protection device 2. And
[0039]
The control / collection means 31 controls the cathodic protection device 2 based on a control signal transmitted from the monitoring / control device 4 via the communication network 11 and automatically and periodically transmits a request from the monitoring / control device 4. , The monitoring data is transmitted to the monitoring / control device 4 through the communication device 30.
[0040]
The monitoring data collected by the control / collection unit 31 include an AC input abnormality from the power system to the rectifier, an output DC voltage from the power supply device 22 (an output voltage of the rectifier circuit 225: a conduction voltage), and an output DC voltage from the power supply device 22. Current (output current of the rectifier circuit 225: conduction current), probe DC current density, and the like.
[0041]
In the present embodiment, the control item of the power supply device 22 by the control / collection unit 31 is ON / OFF of the output of the power supply device 22 by the relay circuit.
[0042]
The control / collection means 31 is constituted by a microcomputer unit. The control / collection unit 31 includes hardware (arithmetic processing device, storage device (main storage and auxiliary storage device), input device, output device, clock, bus, etc.) constituting the microcomputer, and a storage device of the hardware. And terminal software stored in the terminal. The terminal software collects the monitoring data from the cathodic protection device 22 and monitors / controls the monitoring data automatically or periodically at the request of the monitoring / control device 4 through the communication device 30. In addition to functioning to transmit the signal to the device 4, the device 4 functions to control the cathodic protection device 2 based on the control signal transmitted from the monitoring and control device 4 received through the communication device 30 as described above.
[0043]
The monitoring / control device 4 receives the monitoring data transmitted from the control / collecting means 31 through the communication device 30 and the communication device 40 communicating with the communication device 30 of the terminal device 3 via the communication network 11. And a management unit (not shown) for remotely managing the cathodic protection state of the buried pipeline 10 based on the monitoring data, and the terminal device 3 through the communication device 40 to the terminal device 3. And control signal transmitting means (not shown) for transmitting the control signal.
[0044]
The management means of the monitoring and control device 4 determines that the values of the energized voltage, the energized current, and the probe current density (or their respective average values over a certain period) among the monitored data received from the terminal device 3 are set in advance to the appropriate values. If the monitoring data is out of a normal range, it is determined that the monitoring data is abnormal, and that fact, the date and time and each value are associated with the terminal device 3 and the storage device is compared. And output to an output device.
[0045]
Examples of the determination as to whether the monitoring data is normal or abnormal include, for example, when the average value of the energizing voltage is 90% or more of the rated voltage of the rectifier circuit 225; When the value becomes 90% or more of the rated current of the rectifier circuit 225; when the probe current density exceeds the cathode corrosion control range, the average value may be mentioned.
[0046]
The control signal unit of the monitoring / control device 4 automatically sends a control signal corresponding to the control item to the terminal device 3 based on a judgment of the management unit or based on an operation of an operator of the monitoring / control device 4. This is transmitted to the control / collection means 31.
[0047]
The monitoring / control device 4 is specifically composed of a computer system 41 having a communication device 40, and hardware (arithmetic processing device, storage device (main storage and auxiliary storage device), input Device, output device, clock, bus, etc.) and monitoring / control software held in a storage device of the hardware. The monitoring / control software causes the hardware to function as the management unit and the control signal transmission unit.
[0048]
In the monitoring / control device 4 having the above-mentioned configuration, whether there is an AC input abnormality of the power supply device transmitted from the terminal device 3 automatically or periodically based on the operation of the operator of the monitoring / control device 4, the buried pipeline The monitoring data such as the energizing voltage, energizing current, and probe current (or probe current density) to the terminal 10 are appropriately stored in a storage device in association with the terminal device 3 and output to an output device such as a CRT or a printer. Centrally managed remotely. Then, a control signal is transmitted to the control / collection means 31 of the terminal device 3 automatically based on the judgment result of the monitoring data by the management means or in response to the operation of the operator of the monitoring / control device 4, and the cathodic protection is performed. ON / OFF of the output of the power supply device 22 in the device 2 is controlled.
[0049]
Each of the communication devices 30 and 40 of the terminal device 3 and the monitoring / control device 4 can select an appropriate device according to a communication mode between them and a data transmission mode. Examples of the communication device include a modem, a terminal adapter, various routers, and the like. The transmission mode of the control signal and the various monitoring data by each communication device may be any of analog and digital (including packet communication) transmission modes according to the transmission mode of the communication network 11.
[0050]
The communication mode of the communication network 11 that mediates communication between the communication device 30 of the terminal device 3 and the communication device 40 of the monitoring / control device 4 is not particularly limited. As the communication mode, for example, a communication mode via a general telephone line, a dedicated line, the Internet, or a combination thereof involving protocol conversion can be adopted. The communication mode of the communication network 11 may be any of a wired mode and a wireless mode.
[0051]
For example, as shown in FIG. 1, a communication device connectable to the wireless packet network 111 is mounted on the communication device 30 of the terminal device 3, and the monitoring / control device 4 is built on the Internet 110. The wireless packet network 111 is provided so as to be connectable to the Internet 110 via a gateway (not shown). Thereby, the anticorrosion state of the buried pipeline 10 can be monitored and controlled collectively by remote control based on the monitoring data obtained from the terminal device 3. In addition, by registering the monitoring data collected by the monitoring / control device 4 as a web page that can be viewed by a specific person in the auxiliary storage device of the monitoring / control device 4, the monitoring data that can be accessed by the monitoring / control device 4 is specified. May be able to view the monitoring data at any location.
[0052]
As described above, according to the system 1 of this embodiment, the current control circuit 230 of the power supply device 22 incorporates the phase compensation circuit 238 for performing phase lead compensation in addition to the low-pass filter circuit 232, so that the probe current , The AC component contained in the power supply device 22 is effectively attenuated to stabilize the control of the power supply device 22, and the control response of the cathodic protection current can be sped up.
[0053]
Further, the signal common of the detection circuit 234 is separated from the power control circuit 220 by the insulated amplification circuit 233 incorporated in the current control circuit 230 so as not to be affected by the potential fluctuation and noise of the external environment. Stable current detection can be performed, and the control stability of the power supply device 22 can be further improved.
[0054]
Further, according to the system 1 of the present embodiment, since the corrosion protection management of the pipeline 10 by the cathode corrosion protection device 2 can be collectively performed from a remote place, it is possible to improve the security level and reduce the inspection cost. .
[0055]
The present invention is not limited to the above embodiment, and can be appropriately modified without departing from the spirit of the present invention.
[0056]
In the system according to the embodiment, the monitoring / control device determines whether the monitoring data is normal or abnormal.However, the determination is performed in the terminal device, and the determination is stored in the storage device of the terminal device. Is also good.
[0057]
The anticorrosion target to which the present invention is applied is not limited to pipelines, and can be applied to other anticorrosion targets.
[0058]
【Example】
Hereinafter, the present invention will be described more specifically based on examples.
[0059]
As shown in FIG. 1, for a pipeline (polyethylene-coated steel pipe) buried under a train shed (rolling shed), a cathode is provided using a cathodic anticorrosion device equipped with a probe current control type external power supply (see FIG. 2). Anticorrosion was performed. As the cathodic protection device, a device provided with a monitor reference electrode (saturated copper sulfate electrode) connected to a probe via a voltmeter was used. The result is shown in FIG. As a comparative example, FIG. 3B shows a measurement result when no power is supplied to the external power supply device.
[0060]
The control responsiveness of the external power supply was examined under the following measurement conditions. The result is shown in FIG.
[0061]
<Control response measurement conditions>
AC input condition: 200V, 50Hz (rated)
DC output condition: load 2Ω (60V, 30A rating)
[0062]
As shown in FIG. 3B, according to the measurement result of the comparative example, when the ground of the milling machine and the rail are connected to each other and the ground is low, current flows out from the buried pipeline to the probe, and the probe DC current density is reduced. Becomes negative (-), but when the external power supply is energized as shown in the measurement results of the example shown in FIG. 3A, the probe DC current density is always 0.099 to 0.127 mA / cm. ² (set current: 0.1 mA / cm ² ), and control satisfying the cathode corrosion control standard was possible.
[0063]
Further, as shown in FIG. 4, in the step response, the delay time (rise time) was about 20 msec and the settling time was about 150 msec in the actually measured output voltage response waveform. This control responsiveness is sufficient as the control responsiveness in cathodic protection of a buried pipeline.
[0064]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the probe current control type external power supply device of the present invention, the AC component included in the probe current can be effectively attenuated to stabilize the control, and the control response of the anticorrosion current can be sped up.
[0065]
Further, according to the remote control / monitoring system for cathodic protection of the present invention, since the control of cathodic protection can be performed from a remote place, it is possible to improve the security level and reduce the inspection cost.
[Brief description of the drawings]
FIG. 1 is a view schematically showing one embodiment of a cathode corrosion protection remote monitoring / control system of the present invention.
FIG. 2 is a schematic block diagram of one embodiment of a probe current control type external power supply device of the present invention.
3A and 3B are diagrams showing measurement results of a probe current density and a rail leakage current density using the probe current control type external power supply device of the present invention, and FIG. 3A is a diagram showing measurement results before energizing the external power supply device; (B) is a diagram showing a measurement result after power is supplied to the external power supply device.
FIG. 4 is an output voltage response waveform using the probe current control type external power supply device of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cathodic protection remote monitoring and control system 2 Cathodic protection device 20 Energized electrode (anode terminal)
21 Cathode terminal 22 Probe current control type external power supply 220 Power control circuit 230 Current control circuit 232 Low pass filter circuit (filter circuit)
23 Probe 24 Current divider 3 Terminal device 30 Communication device 4 Monitoring / control device 40 Communication device 10 Buried pipeline 11 Communication network

Claims (5)

A power control circuit that supplies an anticorrosion current through a conducting electrode, and a current control circuit that controls the anticorrosion current based on a probe current detected through a probe,
A probe current control type external power supply device, wherein the current control circuit includes a filter circuit and a phase compensation circuit for compensating for a phase advance of an output from the filter circuit. The probe current control type external power supply according to claim 1, wherein the filter circuit is a low-pass filter circuit. The probe current control type external power supply device according to claim 1, wherein the current control circuit includes an insulation amplification circuit. The probe current control type external power supply according to any one of claims 1 to 3, wherein the current control circuit has a notch filter circuit corresponding to a commercial power supply frequency. A cathode protection device having the probe current control type external power supply device according to claim 1, and a terminal that collects monitoring data from the cathode protection device and transmits the collected monitoring data in a predetermined communication form. A cathodic protection remote monitoring and control system comprising: a device; and a monitoring and control device that receives the monitoring data transmitted from the terminal device and remotely monitors and controls the cathodic protection device.

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