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EP0035209B1 - Process for operating an electrofilter - Google Patents

Process for operating an electrofilter Download PDF

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Publication number
EP0035209B1
EP0035209B1 EP81101300A EP81101300A EP0035209B1 EP 0035209 B1 EP0035209 B1 EP 0035209B1 EP 81101300 A EP81101300 A EP 81101300A EP 81101300 A EP81101300 A EP 81101300A EP 0035209 B1 EP0035209 B1 EP 0035209B1
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EP
European Patent Office
Prior art keywords
voltage
microprocessor
filter
values
current
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP81101300A
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German (de)
French (fr)
Other versions
EP0035209A1 (en
Inventor
Helmut Dipl.-Ing. Herklotz
Günter Mehler
Franz Dipl.-Ing. Neulinger
Helmut Dipl.-Ing. Schummer
Horst Dr. Dipl.-Ing. Daar
Walter Dipl.-Ing. Schmidt
Heinrich Winkler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GEA Group AG
Siemens AG
Original Assignee
Metallgesellschaft AG
Siemens AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Priority to AT81101300T priority Critical patent/ATE8110T1/en
Publication of EP0035209A1 publication Critical patent/EP0035209A1/en
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Publication of EP0035209B1 publication Critical patent/EP0035209B1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
    • B03C3/34—Constructional details or accessories or operation thereof
    • B03C3/66—Applications of electricity supply techniques
    • B03C3/68—Control systems therefor

Definitions

  • the invention relates to a method for operating an electrostatic filter, which is fed via an actuator and a high-voltage rectifier from an AC voltage network and in which the actuator can be controlled as a function of electrical filter operating values.
  • This generic term refers to controls such as are known, for example, from Siemens magazine 1971 (number 9), pages 567 to 572, in particular Fig. 2 or DE-AS 1 148 977.
  • filter current and filter voltage are detected and guided depending on breakdowns in such a way that optimum separation conditions result.
  • the previously known controls are generally constructed using means of analog technology, that is to say amplifiers, resistors and capacitors, etc. As digital technology advances, it is desirable to use the microprocessor for control purposes.
  • the object of the present invention is to provide a universally applicable and simple control method for electrostatic filters on a microprocessor basis, which is very versatile with regard to measured value acquisition and processing, but at the same time also has sufficient time available for superordinate control purposes.
  • the electrical filter operating values are queried and stored several times by a microprocessor in a cycle comprising a maximum of 1 1 2 period of the mains AC voltage and the microprocessor in each case sends the required current and voltage values to the control signal of the at the end of the sampling cycle Actuating element, which calculates the superordinate further microprocessor of the same microcomputer system according to predetermined criteria, and immediately transmits only the breakdown signal derived from the comparison of corresponding values of voltage and current in successive half-waves of the DC filter voltage to the superordinate microprocessor.
  • the higher-level microprocessor controlling the start-up and carrying of the voltage at the breakdown limit is kept free of the time-consuming breakdown detection and measured value processing, so that despite the use of two processors (master-slave processor system), a relatively simple microcomputer system results.
  • the primary winding of a high-voltage transformer 3 is connected to an AC network U via a thyristor actuator 4.
  • the actual electrostatic filter 1 is connected to the secondary side of the high-voltage transformer 3 via a rectifier 2.
  • the amplitude of the pulsating DC filter voltage is dependent on the commands of the control unit 41, which in turn receives its control voltage Ust from a microcomputer system 5 serving as a regulator.
  • the microcomputer system 5 consists essentially of a master processor 51 (master) and a slave processor 52 (slave); Both processors 51 and 52 operate on the same bus 57.
  • the memory 53 which is known from read / write memories (RAM) for data and read-only memories (ROM) for the operating system, is also a digital-analog -Converters 56 and an input-output stage 54 are connected for the transmission and reception of process signals.
  • a coupling element 58 also works on the bus, which can maintain the connection to a higher-level control computer 7 (cf. FIG. 2) via a bus system 71.
  • the input of data into the microcomputer system 5 is carried out via a connector 61 by means of a programming device 6.
  • the arrangement works in such a way that values proportional to the primary current Ip, the filter current I F , the filter voltage U F and the control voltage Us t arrive at the processor 52 via an analog-digital converter, are processed there and at the end of their sampling cycle be passed to the control processor 51.
  • the latter calculates the required control commands for the actuator 4 according to predetermined criteria and outputs them to the tax rate 41 via the digital / analog converter 56.
  • the processor 52 also has the task of causing strikethroughs in the filter detect. For this purpose, corresponding voltage or current values are compared with one another in successive half-waves and the breakdown signal is formed therefrom. This signal is immediately passed on to the control processor 51.
  • the formation of this signal - and also other signals - is explained in more detail in connection with FIGS. 3 and 4.
  • FIG. 2 shows the use of such a control in the context of an electrostatic filter system consisting of several electrostatic filters A, B, C, through which the gas to be cleaned flows in the direction of arrow 8.
  • each filter A, B, C is a separate controller, i. H. assigned a microcomputer system 5.
  • Each of these microcomputer systems is connected via the coupling element 58 and a data bus 71 to a superordinate control computer 7 which can calculate superordinate optimization strategies or the like; e.g. B. can be detected by a dust loading meter 9, the separation performance and the separation can be distributed to the individual filters so that there is an optimal degree of separation with minimal energy.
  • the configuration mentioned above has the advantage that even if a microcomputer system 5 fails, the system can continue to be operated as such, since the other controls can continue to work individually. This also applies to the failure of the control processor 7, since even then the individual filters can still be regulated.
  • FIG. 3 shows the course of the pulsating DC filter voltage U F in kV as a function of the time t, with T denoting the period of the mains AC voltage.
  • the arithmetic mean of the filter voltage is also of interest, e.g. B. for recording the filter characteristic, ie the filter current I F as a function of the filter voltage U F.
  • the mean value of the filter current is also of interest.
  • the measured value sum and the number of mean values are also transmitted to the control processor 51, which can then carry out the mean value calculation.
  • the nominal current monitoring is also of interest; this requires the formation of the primary current effective value.
  • all individual measured values Jp which are greater than the magnetizing current, are added in the processor 52 during the duration of a half-wave.
  • the measured value sum, number of single measured values and the peak value of the primary current are transmitted to the master processor 51, which can use this to calculate the effective value based on an approximation.
  • the output control voltage U St is actually present at the tax rate 41.
  • the individual measured values of the thyristor control voltage are also continuously called up and added in each half-wave.
  • the measured value sum and the number of measured values are likewise transmitted to the control processor 51, which carries out the mean value calculation. This must then again match the control voltage output via the digital-to-analog converter 56.
  • the peak values that occur in the 10 millisecond cycle and the arithmetic mean values of the filter voltage U F and the arithmetic mean values of the filter current I F are calculated via z. B. averaged 1 second. These values can then e.g. B. be displayed on a numerical display. If a control processor 7 is present, these second average values can also be averaged over a minute. These values can then be transferred to the control processor on request.
  • Another essential task of processor 52 is to detect a breakdown.
  • a method for detecting the breakdown on the high-voltage side can, for. B. consist in that the voltage profiles of successive half-waves of the fluctuations in voltage U F at the separator are continuously compared with one another and a predetermined deviation of mutually assigned half-wave measured values serves as a criterion for a breakdown.
  • voltage comparisons of successive half-waves of the filter voltage are used, then the comparison of peak values of the primary current and additionally a minimum voltage monitoring.
  • the voltage U FO (N) is signaled by the external signal zero crossing of the mains voltage U with the period T.
  • 20 of these are distributed over half the period Individual measured values Uf (N) of the half-wave (N) are stored.
  • 20 individual measured values U F i (N + 1) of the subsequent half-wave N + 1 are sampled and stored, in the same phase position as that of the previous half-wave (N).
  • the individual measured values of the same phase position of successive half-waves are compared with one another and the voltage differences educated.
  • Each of the individual voltage differences 4 U F i is compared with a limit value, which is a certain percentage of the DC filter voltage.
  • the breakthrough signal is given when the difference is greater than the predetermined limit. As can be seen, there is a filter breakdown at the point D in the half-wave N + 1, since the voltage value present here is considerably smaller than the assigned voltage value in the previous half-wave N.
  • the primary current Ip is rectified and the peak values of a half-wave and the following half-wave ip (N), ip (N + 1) are stored and with the corresponding values ip (N + 2), Ip (N + 3) of the following network period compared. If the comparison of the assigned peak values of two network periods reveals a deviation that goes beyond a certain amount, the amount of which is made dependent on the current strength, the breakthrough processing is also initiated. As an additional criterion for the breakdown, the drop in the filter voltage U F below a predetermined target value is also considered.
  • control parameters such.
  • B. Increase in filter voltage and evaluation of the breakdowns per unit of time etc. can be entered into the control system from the outside by the programming device 6, depending on the filter conditions required. This means that the same control system can be used for a large number of different filters and systems.

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  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Electrostatic Separation (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)
  • Control Of Electrical Variables (AREA)
  • Control Of Voltage And Current In General (AREA)
  • Power Conversion In General (AREA)

Abstract

1. A process for operating an electrofiler circuit which is fed from an alternating voltage supply network by a control element (4) and a high-voltage rectifier (2) and wherein the control element (4) is controlled in dependence upon electrical operating filter data, characterized in that a cycle, which comprises a half-wave of the alternating network supply voltage, the electrical operating filter data is repeatedly sampled and stored by a microprocessor (52), and that at the end of the sampling cycle, the microprocessor (52) transfers the required current and voltage values to a surbonate further microprocessor (51) of the same micro-computer system, which microprocessor calculates the control signal of the control element (1) in accordance with predetermined criteria, and only immediately transmits to the subordinate microprocessor (51) the breakdown signal derived by comparison of corresponding values of voltage and current in successive half-waves of the direct filter voltage.

Description

Die Erfindung bezieht sich auf ein Verfahren zum Betrieb eines Elektrofilters, das über ein Stellglied und einen Hochspannungsgleichrichter aus einem Wechselspannungsnetz gespeist ist und bei dem das Stellglied abhängig von elektrischen Filterbetriebswerten aussteuerbar ist.The invention relates to a method for operating an electrostatic filter, which is fed via an actuator and a high-voltage rectifier from an AC voltage network and in which the actuator can be controlled as a function of electrical filter operating values.

Mit diesem Oberbegriff wird auf Steuerungen Bezug genommen, wie sie beispielsweise aus der Siemens-Zeitschrift 1971 (Heft 9), Seiten 567 bis 572, insbesondere Bild 2 oder der DE-AS 1 148 977 bekannt sind.This generic term refers to controls such as are known, for example, from Siemens magazine 1971 (number 9), pages 567 to 572, in particular Fig. 2 or DE-AS 1 148 977.

Bei diesen bekannten Steuerungen werden unter anderem Filterstrom und Filterspannung erfaßt und abhängig von Durchschlägen so geführt, daß sich optimale Abscheideverhältnisse ergeben.In these known controls, filter current and filter voltage, among other things, are detected and guided depending on breakdowns in such a way that optimum separation conditions result.

Die bisher bekannten Steuerungen sind im allgemeinen mit Mitteln der Analogtechnik, also Verstärkern, Widerständen und Kondensatoren usw. aufgebaut. Im Zuge des Vordringens der Digitaltechnik wird es wünschenswert, auch hier für Steuerungszwecke den Mikroprozessor einzusetzen.The previously known controls are generally constructed using means of analog technology, that is to say amplifiers, resistors and capacitors, etc. As digital technology advances, it is desirable to use the microprocessor for control purposes.

Überträgt man nun Erfassung und Aufbereitung der Meßwerte sowie Weiterverarbeitung und Regelung einem Mikrocomputer mit einem Mikroprozessor, so ist dieser Rechner im allgemeinen durch die Erfassung und Aufbereitung der sich rasch ändernden Meßwerte so beschäftigt, daß für die eigentliche Regelung kaum mehr Zeit bleibt, es sei denn, es wird eine Beschränkung der Meßwerte durchgeführt oder ein aufwendiger Rechner benutzt. Die erste Alternative führt zu einem Verlust an Regelgenauigkeit oder Vielseitigkeit, die zweite Alternative zu erheblichem Kostenaufwand.If one transfers the acquisition and processing of the measured values as well as further processing and control to a microcomputer with a microprocessor, this computer is generally so busy with the acquisition and processing of the rapidly changing measured values that there is hardly any time left for the actual control, unless , the measured values are restricted or an expensive computer is used. The first alternative leads to a loss of control accuracy or versatility, the second alternative to considerable expense.

Hiervon ausgehend besteht die Aufgabe der vorliegenden Erfindung darin, ein universell einsetzbares und einfaches Steuerungsverfahren für Elektrofilter auf Mikroprozessorbasis zu schaffen, das hinsichtlich der Meßwerterfassung und Aufbereitung sehr vielseitig ist, aber gleichzeitig auch für übergeordnete Regelzwekke genügend Zeit zur Verfügung hat.Proceeding from this, the object of the present invention is to provide a universally applicable and simple control method for electrostatic filters on a microprocessor basis, which is very versatile with regard to measured value acquisition and processing, but at the same time also has sufficient time available for superordinate control purposes.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß jeweils in einem maximal 112 Periode der Netzwechselspannung umfassenden Zyklus mehrfach die elektrischen Filterbetriebswerte durch einen Mikroprozessor abgefragt und gespeichert werden und der Mikroprozessor jeweils am Ende des Abtastzyklus die benötigten Strom- und Spannungswerte an einen das Steuersignal des Stellgliedes nach vorgegebenen Kriterien berechnenden, übergeordneten weiteren Mikroprozessor des gleichen Mikrocomputersystems übergibt und nur das aus dem Vergleich korrespondierender Werte von Spannung und Strom in aufeinanderfolgenden Halbwellen der Filtergleichspannung abgeleitete Durchschlagsignal sofort an den übergeordneten Mikroprozessor überträgt.This object is achieved in that the electrical filter operating values are queried and stored several times by a microprocessor in a cycle comprising a maximum of 1 1 2 period of the mains AC voltage and the microprocessor in each case sends the required current and voltage values to the control signal of the at the end of the sampling cycle Actuating element, which calculates the superordinate further microprocessor of the same microcomputer system according to predetermined criteria, and immediately transmits only the breakdown signal derived from the comparison of corresponding values of voltage and current in successive half-waves of the DC filter voltage to the superordinate microprocessor.

Auf diese Weise wird der das Hochfahren und Führen der Spannung an der Durchschlagsgrenze steuernde, übergeordnete Mikroprozessor von der zeitaufwendigen Durchschlagserfassung und Meßwertaufbereitung freigehalten, so daß sich trotz der Verwendung zweier Prozessoren (Master-Slave Prozessorsystem) ein verhältnismäßig einfaches Mikrocomputersystem ergibt.In this way, the higher-level microprocessor controlling the start-up and carrying of the voltage at the breakdown limit is kept free of the time-consuming breakdown detection and measured value processing, so that despite the use of two processors (master-slave processor system), a relatively simple microcomputer system results.

Weitere vorteilhafte Ausgestaltungen der Steuerung sind in den kennzeichnenden Merkmalen der Unteransprüche beschrieben.Further advantageous refinements of the control are described in the characterizing features of the subclaims.

Anhand eines in der Zeichnung dargestellten Ausführungsbeispiels sei die Erfindung näher erläutert; es zeigt

  • Fig. 1 den Schaltungsaufbau der Steuerung,
  • Fig. 2 eine aus mehreren Elektrofiltern bestehende Anlage mit individueller Steuerung je Filter,
  • Fig. 3 einen beispielsweisen Verlauf der pulsierenden Filtergleichspannung und
  • Fig. 4 einen beispielsweisen Verlauf des Primärstromes des Elektrofilters.
The invention will be explained in more detail using an exemplary embodiment shown in the drawing; it shows
  • 1 shows the circuit structure of the control,
  • 2 a system consisting of several electrostatic filters with individual control per filter,
  • 3 shows an example of the course of the pulsating DC filter voltage and
  • Fig. 4 shows an example of the course of the primary current of the electrostatic filter.

Die Primärwicklung eines Hochspannungstransformators 3 ist über ein Thyristorstellglied 4 an ein Wechselspannungsnetz U angeschlossen. Auf der Sekundärseite des Hochspannungstransformators 3 ist über einen Gleichrichter 2 das eigentliche Elektrofilter 1 angeschlossen. Die Amplitude der pulsierenden Filtergleichspannung ist dabei von den Befehlen des Steuersatzes 41 abhängig, der seinerseits seine Steuerspannung Ust aus einem als Regler dienenden Mikrocomputersystem 5 erhält.The primary winding of a high-voltage transformer 3 is connected to an AC network U via a thyristor actuator 4. The actual electrostatic filter 1 is connected to the secondary side of the high-voltage transformer 3 via a rectifier 2. The amplitude of the pulsating DC filter voltage is dependent on the commands of the control unit 41, which in turn receives its control voltage Ust from a microcomputer system 5 serving as a regulator.

Das Mikrocomputersystem 5 besteht im wesentlichen aus einem Leitprozessor 51 (Master) und einem Folgeprozessor 52 (Slave); beide Prozessoren 51 und 52 arbeiten auf den gleichen Bus 57. An diesen Bus 57 sind auch noch der in bekannter Weise aus Schreib-Lesespeichern (RAM) für Daten und Nur-Lesespeichern (ROM) für das Betriebssystem bestehende Speicher 53, ein Digital-Analog-Wandler 56 und eine Eingabe-Ausgabe-Stufe 54 zur Weitergabe und Empfang von Prozeß-Signalen angeschlossen. Ferner arbeitet auf den Bus auch noch ein Koppelglied 58, das die Verbindung zu einem übergeordneten Leitrechner 7 (vgl. Fig. 2) über ein Bussystem 71 aufrechterhalten kann. Die Eingabe von Daten in das Mikrocomputersystem 5 wird über einen Anschlußstecker 61 mittels eines Programmiergerätes 6 vorgenommen. Die Anordnung arbeitet in der Weise, daß dem Primärstrom lp, dem Filterstrom IF, der Filterspannung UF und der Steuerspannung Ust proportionale Werte über einen Analog-Digital-Wandler an den Prozessor 52 gelangen, dort aufbereitet werden und am Schluß ihres Abtastzyklus an den Leitprozessor 51 weitergegeben werden. Dieser berechnet dann nach vorgegebenen Kriterien die erforderlichen Stellbefehle für das Stellglied 4 und gibt diese über den Digital-Analog-Wandler 56 an den Steuersatz 41 aus. Zusätzlich hat der Prozessor 52 noch die Aufgabe, Durchschläge im Filter zu erkennen. Hierzu werden korrespondierende Spannungs- bzw. Stromwerte in aufeinanderfolgenden Halbwellen miteinander verglichen und hieraus das Durchschlagsignal gebildet. Dieses Signal wird sofort an den Leitprozessor 51 weitergegeben. Die Bildung dieses Signals - und auch anderer Signale - ist in Zusammenhang mit den Fig. 3 und 4 näher erläuert.The microcomputer system 5 consists essentially of a master processor 51 (master) and a slave processor 52 (slave); Both processors 51 and 52 operate on the same bus 57. On this bus 57, the memory 53, which is known from read / write memories (RAM) for data and read-only memories (ROM) for the operating system, is also a digital-analog -Converters 56 and an input-output stage 54 are connected for the transmission and reception of process signals. Furthermore, a coupling element 58 also works on the bus, which can maintain the connection to a higher-level control computer 7 (cf. FIG. 2) via a bus system 71. The input of data into the microcomputer system 5 is carried out via a connector 61 by means of a programming device 6. The arrangement works in such a way that values proportional to the primary current Ip, the filter current I F , the filter voltage U F and the control voltage Us t arrive at the processor 52 via an analog-digital converter, are processed there and at the end of their sampling cycle be passed to the control processor 51. The latter then calculates the required control commands for the actuator 4 according to predetermined criteria and outputs them to the tax rate 41 via the digital / analog converter 56. In addition, the processor 52 also has the task of causing strikethroughs in the filter detect. For this purpose, corresponding voltage or current values are compared with one another in successive half-waves and the breakdown signal is formed therefrom. This signal is immediately passed on to the control processor 51. The formation of this signal - and also other signals - is explained in more detail in connection with FIGS. 3 and 4.

Fig. 2 zeigt den Einsatz einer derartigen Steuerung im Rahmen einer aus mehreren Elektrofiltern A, B, C bestehenden Elektrofilteranlage, die in Richtung des Pfeiles 8 von dem zu reinigenden Gas durchströmt wird. Wie ersichtlich, ist jedem Filter A, B, C eine eigene Steuerung, d. h. ein Mikrocomputersystem 5 zugeordnet. Jedes dieser Mikrocomputersysteme steht über das Koppelglied 58 und einen Datenbus 71 mit einem übergeordneten Leitrechner 7 in Verbindung, der übergeordnete Optimierungsstrategien oder dgl. berechnen kann; z. B. kann durch ein Staubbeladungsmeßgerät 9 die Abscheideleistung erfaßt und die Abscheidung so auf die einzelnen Filter verteilt werden, daß sich bei minimalem Energieaufwand ein optimaler Abscheidungsgrad ergibt. Die vorstehend erwähnte Konfiguration hat den Vorteil, daß auch bei Ausfall eines Mikrocomputersystems 5 die Anlage als solche weiterbetrieben werden kann, da die anderen Steuerungen individuell für sich weiterarbeiten können. Ebenso gilt dies für den Ausfall des Leitprozessors 7, da auch dann noch immer die einzelnen Filter regelbar sind.FIG. 2 shows the use of such a control in the context of an electrostatic filter system consisting of several electrostatic filters A, B, C, through which the gas to be cleaned flows in the direction of arrow 8. As can be seen, each filter A, B, C is a separate controller, i. H. assigned a microcomputer system 5. Each of these microcomputer systems is connected via the coupling element 58 and a data bus 71 to a superordinate control computer 7 which can calculate superordinate optimization strategies or the like; e.g. B. can be detected by a dust loading meter 9, the separation performance and the separation can be distributed to the individual filters so that there is an optimal degree of separation with minimal energy. The configuration mentioned above has the advantage that even if a microcomputer system 5 fails, the system can continue to be operated as such, since the other controls can continue to work individually. This also applies to the failure of the control processor 7, since even then the individual filters can still be regulated.

Der vorstehend erwähnte modulare Aufbau führt außerdem zu Vorteilen bei Wartung und Nachrüstung von Elektrofilteranlagen und bietet ein Maximum an Störsicherheit. Fig. 3 zeigt den Verlauf der pulsierenden Filtergleichspannung UF in kV in Abhängigkeit von der Zeit t, wobei mit T die Periodendauer der Netzwechselspannung bezeichnet ist. In jeder Halbperiode N, N + 1 uws. der Netzwechselspannung U wird die Filterspannung UF 20 x abgetastet, d. h. die Einzelwerte UFi(N) von i = 0 bis i = 20 vom Mikroprozessor 52 abgefragt und gespeichert. Tritt während der Halbwelle, d. h. im Abtastzyklus, kein Durchbruch auf, so wird in jeder Halbwelle N im Prozessor 52 der Scheitelwert Umax ermittelt und bei Beginn der nächsten Halbwelle N + 1 an den Leitprozessor 51 übergeben. Dieser nimmt die automatische Anpassung der Filterspannung an die sich ändernden Betriebsverhältnisse des Elektrofilters vor. Außer dem für die Durchschlaggrenze wichtigen Scheitelwert Umax ist auch der arithmetische Mittelwert der Filterspannung von Interesse, z. B. zur Aufnahme der Filtercharakteristik, d. h. des Fiterstromes IF in Abhängigkeit von der Filterspannung UF. Hierzu wird am Ende jeder Spannungshalbwelle N die Summe äsämtlicher Meßwerte und die Anzahl, z. B. 20 an den Leitprozessor 51 übertragen, der hieraus dann den Mittelwert berechnet.The modular structure mentioned above also leads to advantages in the maintenance and retrofitting of electrostatic precipitator systems and offers maximum interference immunity. 3 shows the course of the pulsating DC filter voltage U F in kV as a function of the time t, with T denoting the period of the mains AC voltage. In each half period N, N + 1 etc. the AC voltage U, the filter voltage U F is sampled 20 times, ie the individual values U Fi (N) from i = 0 to i = 20 are queried and stored by the microprocessor 52. If no breakthrough occurs during the half-wave, ie in the sampling cycle, then the peak value U max is determined in the processor 52 in each half-wave N and transferred to the control processor 51 at the beginning of the next half-wave N + 1. This automatically adjusts the filter voltage to the changing operating conditions of the electrostatic filter. In addition to the peak value U max, which is important for the breakdown limit , the arithmetic mean of the filter voltage is also of interest, e.g. B. for recording the filter characteristic, ie the filter current I F as a function of the filter voltage U F. For this purpose, the sum of all measured values and the number, for. B. 20 to the control processor 51, which then calculates the mean value therefrom.

Von Interesse ist auch der Mittelwert des Filterstromes. Hierzu werden im Prozessor 52 die Einzelmeßwerte des Filterstroms IF, z. B. 20, während der Dauer einer Halbwelle addiert. Bei Beginn der nächsten Halbwelle wird die Meßwertsumme und die Anzahl der Mittelwerte ebenfalls an den Leitprozessor 51 übertragen, der dann die Mittelwertberechnung ausführen kann.The mean value of the filter current is also of interest. For this purpose, the individual measured values of the filter current I F , z. B. 20, added during the duration of a half wave. At the beginning of the next half-wave, the measured value sum and the number of mean values are also transmitted to the control processor 51, which can then carry out the mean value calculation.

Von Interesse ist auch die Nennstromüberwachung; hierzu ist die Bildung des Primärstromeffektivwertes notwendig. Hierzu werden im Prozessor 52 alle Einzelmeßwerte Jp, die größer als der Magnetisierungsstrom sind, während der Dauer einer Halbwelle addiert. Bei Beginn der nächsten Halbwelle wird die Meßwertsumme, Anzahl der Einzeimeßwerte und der Scheitelwert des Primärstroms an den Master-Prozessor 51 übertragen, der hieraus nach einer Näherungslösung den Effektivwert berechnen kann.The nominal current monitoring is also of interest; this requires the formation of the primary current effective value. For this purpose, all individual measured values Jp, which are greater than the magnetizing current, are added in the processor 52 during the duration of a half-wave. At the beginning of the next half-wave, the measured value sum, number of single measured values and the peak value of the primary current are transmitted to the master processor 51, which can use this to calculate the effective value based on an approximation.

Von weiterem Interesse ist, ob die ausgegebene Steuerspannung USt auch tatsächlich am Steuersatz 41 vorliegt. Hierzu werden in jeder Halbwelle ebenfalls die Einzelmeßwerte der Thyristorsteuerspannung fortlaufend abgerufen und addiert. Bei Beginn der nächsten Halbwelle wird die Meßwertsumme und die Meßwertanzahl ebenfalls an den Leitprozessor 51 übertragen, der die Mittelwertberechnung ausführt. Diese muß dann wieder mit der über den Digital-Analog-Wandler 56 ausgegebenen Steuerspannung übereinstimmen.It is of further interest whether the output control voltage U St is actually present at the tax rate 41. For this purpose, the individual measured values of the thyristor control voltage are also continuously called up and added in each half-wave. At the beginning of the next half-wave, the measured value sum and the number of measured values are likewise transmitted to the control processor 51, which carries out the mean value calculation. This must then again match the control voltage output via the digital-to-analog converter 56.

Im Leitprozessor 51 selbst werden die im 10-Millisekundenzyklus anfallenden Scheitelwerte und die arithmetischen Mittelwerte der Filterspannung UF sowie die arithmetischen Mittelwerte des Filterstroms IF über z. B. 1 Sekunde gemittelt. Diese Werte können dann z. B. an einer Ziffernanzeige angezeigt werden. Falls ein Leitprozessor 7 vorhanden ist, können diese Sekundenmittelwerte zusätzlich über eine Minute gemittelt werden. Diese Werte können dann auf Anforderung in den Leitprozessor übertragen werden.In the master processor 51 itself, the peak values that occur in the 10 millisecond cycle and the arithmetic mean values of the filter voltage U F and the arithmetic mean values of the filter current I F are calculated via z. B. averaged 1 second. These values can then e.g. B. be displayed on a numerical display. If a control processor 7 is present, these second average values can also be averaged over a minute. These values can then be transferred to the control processor on request.

Eine weitere wesentliche=Aufgabe des Prozessors 52 besteht in der Erfassung eines Durchschlags.Another essential task of processor 52 is to detect a breakdown.

Ein Verfahren zum hochspannungsseitigen Erfassen des Durchschlags kann z. B. darin bestehen, daß jeweils die Spannungsverläufe aufeinanderfolgender Halbwellen der Schwankungen der Spannung UF am Abscheider miteinander fortlaufend verglichen werden und eine vorgegebene Abweichung einander zugeordneter Halbwellenmeßwerte als Kriterium für einen Durchschlag dient. Bei der hier vorliegenden Steuerung werden einmal Spannungsvergleiche aufeinanderfolgender Halbwellen der Filterspannung, dann der Vergleich von Scheitelwerten des Primärstromes und zusätzlich noch eine Mindestspannungsüberwachung verwendet. Hierzu werden, wie bereits ausgeführt, die Halbwellen der Filterspannung UF (vgl. Fig. 3) z. B. 20 x - Abtastungen i = 0, 1, 2 ... - pro Halbwelle N abgetastet, wobei der Halbwellenbeginn mit z. B. der Spannung UFO(N) durch das externe Signal Null-Durchgang der Netzspannung U mit der Periode T signalisiert wird. In dem dem Mikroprozessor 52 zugeordneten Speicherteil werden 20 dieser über die halbe Periode verteilte Einzelmeßwerte Uf(N) der Halbwelle (N) gespeichert. Anschließend werden 20 Einzelmeßwerte UFi(N + 1) der nachfolgenden Halbwelle N + 1 abgetastet und gespeichert, und zwar von gleicher Phasenlage wie die der vorhergehenden Halbwelle (N). Die Einzelmeßwerte gleicher Phasenlage aufeinanderfolgender Halbwellen werden miteinander verglichen und die Spannungsdifferenzen

Figure imgb0001
gebildet. Jeder der Einzelspannungsdifferenzen 4 UFi wird mit einem Grenzwert verglichen, der ein bestimmter Prozentsatz der Filtergleichspannung ist. Das Durchbruchssignal wird gegeben, wenn die Differenz größer als der vorgegebene Grenzwert ist. Wie ersichtlich, liegt an der Stelle D in der Halbwelle N + 1 ein Filterdurchschlag vor, da der hier vorliegende Spannungswert erheblich kleiner als der zugeordnete Spannungswert in der vorhergehenden Halbwelle N ist.A method for detecting the breakdown on the high-voltage side can, for. B. consist in that the voltage profiles of successive half-waves of the fluctuations in voltage U F at the separator are continuously compared with one another and a predetermined deviation of mutually assigned half-wave measured values serves as a criterion for a breakdown. In the present control, voltage comparisons of successive half-waves of the filter voltage are used, then the comparison of peak values of the primary current and additionally a minimum voltage monitoring. For this purpose, as already stated, the half-waves of the filter voltage U F (see FIG. 3) z. B. 20 x - samples i = 0, 1, 2 ... - sampled per half-wave N, the half-wave beginning with z. B. the voltage U FO (N) is signaled by the external signal zero crossing of the mains voltage U with the period T. In the memory part assigned to the microprocessor 52, 20 of these are distributed over half the period Individual measured values Uf (N) of the half-wave (N) are stored. Subsequently, 20 individual measured values U F i (N + 1) of the subsequent half-wave N + 1 are sampled and stored, in the same phase position as that of the previous half-wave (N). The individual measured values of the same phase position of successive half-waves are compared with one another and the voltage differences
Figure imgb0001
 educated. Each of the individual voltage differences 4 U F i is compared with a limit value, which is a certain percentage of the DC filter voltage. The breakthrough signal is given when the difference is greater than the predetermined limit. As can be seen, there is a filter breakdown at the point D in the half-wave N + 1, since the voltage value present here is considerably smaller than the assigned voltage value in the previous half-wave N.

Zur Überwachung des Stromkriteriums (vgl. Fig. 4) wird der Primärstrom Ip gleichgerichtet und jeweils die Scheitelwerte einer Halbwelle und der folgenden Halbwelle ip(N), ip(N + 1) gespeichert und mit den entsprechenden Werten ip(N + 2), Ip(N + 3) der folgenden Netzperiode verglichen. Ergibt der Vergleich der zugeordneten Scheitelwerte zweier Netzperioden eine über einen bestimmten Betrag hinausgehende Abweichung, deren Höhe von der vorligenden Stromstärke abhängig gemacht ist, so wird ebenfalls die Durchbruchsverarbeitung angestoßen. Als zusätzliches Kriterium für den Durchschlag wird auch noch das Absinken der Filterspannung UF unter einen vorgegebenen Sollwert angesehen.To monitor the current criterion (cf. FIG. 4), the primary current Ip is rectified and the peak values of a half-wave and the following half-wave ip (N), ip (N + 1) are stored and with the corresponding values ip (N + 2), Ip (N + 3) of the following network period compared. If the comparison of the assigned peak values of two network periods reveals a deviation that goes beyond a certain amount, the amount of which is made dependent on the current strength, the breakthrough processing is also initiated. As an additional criterion for the breakdown, the drop in the filter voltage U F below a predetermined target value is also considered.

Von besonderem Interesse ist auch noch bei der vorliegenden Steuerung, daß die Regelparameter, wie z. B. Anstieg der Filterspannung und Bewertung der Durchschläge pro Zeiteinheit usw. je nach den geforderten Filterbedingungen von außen durch das Programmiergerät 6 in die Steuerung eingegeben werden können. Hierdurch kann die gleiche Steuerung für eine Vielzahl von unterschiedlichen Filtern und Anlagen verwendet werden.Of particular interest is also in the present control that the control parameters such. B. Increase in filter voltage and evaluation of the breakdowns per unit of time etc. can be entered into the control system from the outside by the programming device 6, depending on the filter conditions required. This means that the same control system can be used for a large number of different filters and systems.

Claims (8)

1. A process for operating an electrofilter circuit which is fed from an alternating voltage supply network by a control element (4) and a high- voltage rectifier (2) and wherein the control element (4) is controlled in dependence upon electrical operating filter data, characterized in that in a cycle, which comprises a half-wave of the alternating network supply voltage, the electrical operating filter data is repeatedly sampled and stored by a microprocessor (52), and that at the end of the sampling cycle, the microprocessor (52) transfers the required current and voltage values to a subordinate further microprocessor (51) of the same micro-computer system, which microprocessor calculates the control signal of the control element (4) in accordance with predetermined criteria, and only immediately transmits to the subordinate microprocessor (51) the breakdown signal derived by comparison of corresponding values of voltage and current in successive half-waves of the direct filter voltage.
2. A process as claimed in claim 1, characterized in that in the microprocessor (52) the peak value is determined from the sampled filter voltage values of each half-period and transferred to the superordinate processor (51) at the end of the sampling period.
3. A process as claimed in claim 1, characterized in that the figure and sum of the measured voltage and current values are transferred to the superordinate microprocessor (51) by the microprocessor (52) at the end of each sampling cycle.
4. A process as claimed in claim 1, characterized in that the figure and sum of the control voltage values of the control element (4) are determined in each sampling cycle and transferred to the superordinate microprocessor (51).
5. A process as claimed in claim 1, characterized in that in the superordinate processor (51), longduration mean values of filter current and filter voltage are calculated for a display.
6. A process as claimed in claim 1, characterized in that the sampling cycles are synchronised with the zero transits of ther alternating network supply voltage (U).
7. A process as claimed in claim 1, characterized by stores for filter parameters connected to the microcomputerbus (57).
8. A process for the operation of a plurality of filters as claimed in claim 1, within the scope of an electrofilter circuit arrangement which consists of a plurality of filters (A, B, C), characterized by a master computer (7) superimposed on the similar controls of the filters (A, B, C) to optimise and coordinate the filter arrangement.
EP81101300A 1980-02-27 1981-02-23 Process for operating an electrofilter Expired EP0035209B1 (en)

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AT81101300T ATE8110T1 (en) 1980-02-27 1981-02-23 PROCEDURE FOR OPERATING AN ELECTRIC FILTER.

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DE3007364 1980-02-27
DE19803007364 DE3007364A1 (en) 1980-02-27 1980-02-27 CONTROL FOR AN ELECTRIC FILTER

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EP0035209B1 true EP0035209B1 (en) 1984-06-27

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DE3219663A1 (en) * 1982-05-26 1983-12-01 Metallgesellschaft Ag, 6000 Frankfurt Process for detecting breakdowns in an electrostatic filter
DE3233249C2 (en) * 1982-09-08 1986-10-02 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Method for controlling an electrostatic precipitator and control device for carrying out the method
DE3326041A1 (en) * 1983-07-20 1985-02-07 Siemens AG, 1000 Berlin und 8000 München CONTROL DEVICE FOR AN ELECTRIC FILTER
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EP0569838A1 (en) * 1992-05-15 1993-11-18 Siemens Aktiengesellschaft Control process and control device for an electrofilter
US5378978A (en) * 1993-04-02 1995-01-03 Belco Technologies Corp. System for controlling an electrostatic precipitator using digital signal processing
DE10000186C2 (en) * 2000-01-05 2003-09-04 Sartorius Gmbh Device and system for crossflow filtration
RU2323048C1 (en) * 2006-08-23 2008-04-27 ОАО "Хабаровская ремонтно-монтажная компания" Device for automatic control of electric filter of boiler
RU2323782C1 (en) * 2006-08-23 2008-05-10 ОАО "Хабаровская ремонтно-монтажная компания" Method of automatic control of boiler electrostatic precipitator
RU2323781C1 (en) * 2006-08-23 2008-05-10 Василий Вячеславович Ермаков Apparatus for automatic control of boiler electrostatic precipitator

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DE3007364A1 (en) 1981-09-10
DE3164359D1 (en) 1984-08-02
EP0035209A1 (en) 1981-09-09
ATE8110T1 (en) 1984-07-15

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