An energy-saving electrostatic precipitator high-voltage power supply and control method thereof

Abstract

The name of the present invention is an energy-saving electrostatic precipitator high-voltage power supply and its control method. It belongs to the technical field of electrostatic precipitator high-voltage power supply. It mainly solves the problems of the existing electrostatic precipitator composite pulse high-voltage power supply, which requires two sets of power supply systems, such as complex system, high failure rate and poor fault tolerance. Its main features are: it includes a current limiting reactor, a rectifier unit, a high-frequency inverter unit, a high-frequency transformer, a DC voltage superposition unit and a pulse voltage superposition unit electrically connected in sequence; the high-frequency transformer is a high-frequency single-phase transformer with a single winding on the primary side and multiple windings on the secondary side; the DC voltage superposition unit includes a plurality of DC voltage circuits connected in sequence, and the pulse voltage superposition unit includes a plurality of pulse voltage circuits connected in sequence. The present invention has the characteristics of small size, adjustable pulse width and amplitude, multiple output characteristics and dust removal body energy storage, improves the dust removal efficiency of the electrostatic precipitator system and reduces power consumption, and is mainly used for high-voltage power supply in the electrostatic precipitator system.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrostatic precipitator high-voltage power supplies, and in particular relates to an energy-saving electrostatic precipitator high-voltage power supply and a control method thereof. Background Art

[0002] In electrostatic precipitator systems, increasing the output voltage of the high-voltage power supply can stimulate more high-energy electrons, improving dust collection efficiency and particularly effective at filtering fine particulate matter such as PM2.5. However, increasing the field strength can easily lead to flashover discharges, and frequent flashovers can disrupt the system's operation. According to electrostatic precipitator theory, the greater the dust's velocity, the higher the efficiency, and this velocity is directly proportional to the corona field strength. Pulsed power supply can resolve the conflict between excessive field strength and gas breakdown. An electrostatic precipitator composite pulse power supply consists of two coupled power supply systems: a base unit provides DC voltage, and a pulse unit provides pulse voltage. These two voltages are superimposed through a coupling circuit and supplied to the dust collector itself. Due to the wide range and variability of flue gas operating conditions, especially for small and medium-sized ESP projects, the high-voltage power supply's adaptability to these operating conditions is highly demanding. The power supply should be capable of outputting smooth DC voltage, DC voltage superimposed on pulse voltage, low voltage with high current, and high voltage with low current.

[0003] The current electrostatic precipitator composite pulse power supply scheme, the schematic diagram is as follows Figure 1 As shown, it includes a switch unit, a filter inductor, a first three-phase rectifier bridge, an inverter unit, an isolation transformer, a second three-phase rectifier bridge, a pulse resonant circuit, a pulse transformer, a high-voltage coupling capacitor, an isolation inductor, and a basic power supply system. The three-phase grid voltage passes through the switch unit and is sent to the filter reactor. It is converted to DC voltage after passing through the first three-phase rectifier bridge. The DC voltage is inverted into an AC voltage with adjustable amplitude by the three-phase inverter circuit. The voltage is then boosted and isolated from the grid by the isolation transformer. The voltage is rectified to a DC voltage with adjustable amplitude by the second three-phase rectifier bridge. A pulse generating circuit generates a resonant current, which is coupled to the resonant current on the high-voltage side by a pulse high-voltage transformer. A pulse voltage is generated on top of the basic voltage through the high-voltage coupling capacitor to power the dust collector, thereby improving the electrostatic precipitator system's ability to charge dust particles. The required basic voltage can be generated by an industrial frequency or high-frequency high-voltage DC power supply.

[0004] The main deficiencies are: 1. There are two systems, basic power supply and pulse power supply, in the electrical cabinet. The system is complex, with high failure rate and poor fault tolerance; 2. There are filter inductors, inverter circuits, isolation transformers, etc. in the electrical cabinet, which have high power consumption and difficulty in heat dissipation; 3. The IGBT in the pulse forming circuit works in a pulse current state, and the instantaneous current is above 3000A, which causes electromagnetic interference to the surrounding electrical equipment and affects the normal operation of other equipment; 4. The frequency and amplitude of the resonant current generated by the pulse generating circuit are closely related to the parasitic parameters of the pulse high-voltage transformer, and strict requirements are placed on the process consistency and long-term stability of the integrated parameters of the pulse transformer; 5. The current passing through the pulse high-voltage transformer is a large pulse current. In order to ensure that the magnetic core is not saturated, a large amount of magnetic material is required, but the utilization rate is very low. At the same time, the existence of the pulse transformer limits the further improvement of the output instantaneous power of the pulse power supply; 6. The pulse voltage formed on the main body by the current output by the pulse high-voltage transformer is closely related to the load characteristics of the main body, and the adaptability to working conditions is poor. Summary of the Invention

[0005] The purpose of the present invention is to address the above-mentioned shortcomings and propose an energy-saving electrostatic precipitator high-voltage power supply and its control method, which can achieve adjustable pulse width and amplitude, multiple output characteristics and dust removal body energy storage by using only one power supply system.

[0006] The technical solution of the electrostatic precipitator high-voltage power supply of the present invention is: an energy-saving electrostatic precipitator high-voltage power supply, characterized in that: it comprises a current limiting inductor, a rectifier unit, a high-frequency inverter unit, a high-frequency transformer, a DC voltage superposition unit and a pulse voltage superposition unit electrically connected in sequence; the high-frequency transformer is a high-frequency transformer with a primary single winding and a secondary multi-winding structure; the DC voltage superposition unit includes a plurality of DC voltage circuits corresponding to part of the secondary multi-windings, the input ends of the plurality of DC voltage circuits are respectively connected to the output ends of the part of the secondary multi-windings, and the output ends are connected in sequence; the pulse voltage superposition unit includes a plurality of pulse voltage circuits corresponding to another part of the secondary multi-windings, the input ends of the plurality of pulse voltage circuits are respectively connected to the output ends of the other part of the secondary multi-windings, and the output ends are connected in sequence.

[0007] The positive output end of the DC voltage circuit described in the technical solution of the electrostatic precipitator high-voltage power supply of the present invention is connected to the negative output end of the adjacent DC voltage circuit; the inverter output end of the pulse voltage circuit is connected to the positive pole of the adjacent pulse voltage circuit.

[0008] The high-frequency transformer described in the technical solution of the electrostatic precipitator high-voltage power supply of the present invention is a single-phase transformer, and its secondary multi-winding is n1+n2 groups; the multiple DC voltage circuits are n1; the multiple pulse voltage circuits are n2; wherein the number of n1 and n2 is configured according to the rated parameters of the high-voltage power supply.

[0009] The DC voltage circuit described in the technical solution of the electrostatic precipitator high-voltage power supply of the present invention is composed of a rectifier circuit and a filter circuit; the pulse voltage circuit is composed of a rectifier circuit, a filter circuit and a half-bridge inverter circuit.

[0010] The technical solution for the electrostatic precipitator high-voltage power supply of the present invention comprises a rectifier bridge circuit composed of diodes; a filter circuit comprising an energy storage capacitor; and a half-bridge inverter circuit comprising two series-connected IGBTs, which form the upper and lower arms of the inverter half-bridge, respectively. By controlling the switching on and off of the upper and lower arms of the half-bridge inverter circuit, a combination of multiple output voltages can be achieved.

[0011] The current-limiting reactor described in the technical solution of the electrostatic precipitator high-voltage power supply of the present invention includes a three-phase current-limiting reactor connected between the three-phase power grid and the rectifier unit.

[0012] The rectifier unit described in the technical solution of the electrostatic precipitator high-voltage power supply of the present invention includes a rectifier bridge and a filter capacitor.

[0013] The high-frequency inverter unit described in the technical solution of the electrostatic precipitator high-voltage power supply of the present invention is composed of a single-phase IGBT inverter bridge and a resonant capacitor.

[0014] The technical solution of the control method of the present invention is: a control method for an energy-saving electrostatic precipitator high-voltage power supply, characterized in that: by selecting the opening and closing combinations of the upper and lower bridge arms of the half-bridge inverter circuit in n2 pulse voltage circuits, the equivalent high-ratio DC voltage output, equivalent low-ratio DC voltage output and DC voltage superimposed pulse voltage output of the high-frequency transformer are realized, so that a power supply system can realize the output capability of DC voltage superimposed pulse voltage.

[0015] In the technical solution of the control method of the present invention, by controlling the upper bridge arm of the inverter half-bridge in n2 pulse voltage circuits to be turned off and the lower bridge arm to be partially or fully turned on and kept in the turned-on state, the equivalent transformation ratio of the high-frequency transformer is changed, so that the high-voltage power supply outputs DC voltages of different voltage levels; the basic voltage is provided by n1 DC voltage circuits, and by controlling the upper bridge arm of the inverter half-bridge in n2 pulse voltage circuits to be turned off and the lower bridge arm to be partially or fully turned on, and then turned off after a period of time, a DC voltage superimposed on a pulse voltage is provided to the load; the lower bridge arm remains turned off, and by controlling the opening of some upper bridge arms of the inverter half-bridge, the charge on the load parasitic capacitance after the pulse voltage is formed is returned to the filter capacitor of the DC voltage superposition unit and the pulse voltage superposition unit.

[0016] The present invention adopts an energy-saving electrostatic precipitator high-voltage power supply composed of a current-limiting inductor, a rectifier unit, a high-frequency inverter unit, a high-frequency transformer, a DC voltage superposition unit and a pulse voltage superposition unit electrically connected in sequence, wherein the high-frequency transformer is a high-frequency single-phase transformer with a single winding on the primary side and multiple windings on the secondary side. The DC voltage superposition unit includes a plurality of DC voltage circuits corresponding to part of the secondary multi-windings, and the input ends of the plurality of DC voltage circuits are respectively connected to the output ends of the part of the secondary multi-windings, and the output ends are connected in sequence. The pulse voltage superposition unit includes a plurality of pulse voltage circuits corresponding to another part of the secondary multi-windings, and the input ends of the plurality of pulse voltage circuits are respectively connected to the output ends of the other part of the secondary multi-windings, and the output ends are connected in sequence. Therefore, by controlling the on-off combination of the upper and lower bridge arms of the half-bridge inverter circuit in the pulse voltage superposition unit, different output characteristics of the high-voltage power supply, such as high basic DC voltage, low basic DC voltage, and DC voltage superposition pulse voltage, can be achieved.

[0017] This invention features a compact size, adjustable pulse width and amplitude, multiple output characteristics, and energy storage within the dust collector itself. It improves the dust removal efficiency of electrostatic precipitators while reducing power consumption. It is primarily used as a high-voltage power supply in electrostatic precipitators, converting three-phase AC voltage into the high voltage required by electrostatic precipitators. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a circuit diagram of a composite pulse power supply for electrostatic precipitator in the prior art.

[0019] Figure 2 It is a topological diagram of the high-voltage power supply circuit of the electrostatic precipitator of the present invention.

[0020] Figure 3 This is the output waveform diagram after the basic power supply of the present invention is superimposed with the pulse power supply.

[0021] In the figure: 1. Current-limiting reactor; 2. Rectifier unit; 3. High-frequency inverter unit; 4. High-frequency transformer; 5. Basic voltage superposition unit; 6. Pulse voltage superposition unit. DETAILED DESCRIPTION

[0022] The present invention will be further described below with reference to the accompanying drawings.

[0023] like Figure 2 As shown, an embodiment of an energy-saving electrostatic precipitator high-voltage power supply of the present invention includes a current limiting inductor 1, a rectifier unit 2, a high-frequency inverter unit 3, a high-frequency transformer 4, a basic voltage superposition unit 5 and a pulse voltage superposition unit 6 electrically connected in sequence, and the high-frequency transformer 4 is a high-frequency single-phase transformer with a single winding on the primary side and multiple windings on the secondary side.

[0024] The DC voltage superposition unit 5 includes n1 DC voltage circuits corresponding to a portion of the secondary multi-windings. The DC voltage circuits consist of a rectifier circuit and a filter circuit. The input ends of the n1 DC voltage circuits are respectively connected to the output ends of the portion of the secondary multi-windings, and the positive output ends are connected to the negative output ends of the adjacent DC voltage circuits, providing a DC base voltage to the load. The pulse voltage superposition unit 6 includes n2 pulse voltage circuits corresponding to another portion of the secondary multi-windings. The pulse voltage circuits consist of a rectifier circuit, a filter circuit, and an inverter half-bridge circuit. The input ends of the n2 pulse voltage circuits are respectively connected to the output ends of the portion of the secondary multi-windings, and the inverter output ends are connected to the positive output ends of the adjacent pulse voltage circuits, providing a pulse voltage to the load. Among them, the rectifier circuit is a rectifier bridge circuit composed of diodes, the filter circuit is composed of energy storage capacitors, and the half-bridge inverter circuit is composed of two IGBTs connected in series. The two IGBTs constitute the upper arm of the inverter half-bridge and the lower arm of the inverter half-bridge respectively. By controlling the opening and closing of the upper and lower arms of the pulse voltage superposition unit, the superposition and combination output of multiple voltage forms can be realized, thereby realizing direct energy exchange with the dust removal body.

[0025] The current-limiting reactor 1 includes a three-phase current-limiting reactor connected between the three-phase power grid and the rectifier unit 2 to convert AC voltage into DC voltage.

[0026] The rectifier unit 2 includes a rectifier bridge and a filter capacitor.

[0027] The high-frequency inverter unit 3 is composed of a single-phase IGBT inverter bridge and a resonant capacitor. The high-frequency inverter unit 3 inverts the DC voltage into a high-frequency AC voltage, and then transmits the resonant capacitor and resonant inductor to the high-frequency transformer 4.

[0028] The four secondary windings of the high-frequency transformer are n1+n2 groups, where n1 group corresponds to n1 DC voltage circuits, and n2 group corresponds to n2 pulse voltage circuits. The number of n1 and n2 is configured according to the application scenario and can be any value.

[0029] The present invention provides a control method for an energy-saving electrostatic precipitator high-voltage power supply. The method realizes an equivalent high-transformation ratio DC voltage output, an equivalent low-transformation ratio DC power supply output, and a DC voltage superimposed pulse voltage output of a high-frequency transformer 4 by selecting an on / off combination of upper and lower bridge arms of a half-bridge inverter circuit in n2 pulse voltage circuits. The method changes the equivalent transformation ratio of the high-frequency transformer 4 and enables the high-voltage power supply to output DC voltages of different voltage levels by controlling the upper bridge arms of the inverter half-bridge in the n2 pulse voltage circuits to be turned off and the lower bridge arms to be partially or fully turned on and maintained in the on state. The method provides a basic voltage through n1 DC voltage circuits, and provides a DC voltage superimposed pulse voltage to a load by controlling the upper bridge arms of the inverter half-bridge in n2 pulse voltage circuits to be turned off and the lower bridge arms to be partially or fully turned on, maintained for a period of time, and then turned off. The lower bridge arm remains turned off, and by controlling the opening of some upper bridge arms of the inverter half-bridge, the charge on the load parasitic capacitance after the pulse voltage is formed flows back to the filter capacitors of the DC voltage superposition unit and the pulse voltage superposition unit for recovery, thereby reducing the pulse width and saving electric energy.

[0030] Example 1 of the control method of the present invention:

[0031] Taking the equipment with 60kV / 1000mA DC voltage + 60kV pulse power supply as an example, when the dust collector body needs to output 80kV DC voltage but does not need DC voltage superimposed on pulse voltage, the upper bridge arm of the half-bridge inverter circuit of one-third of the pulse voltage superposition unit can be kept off and the lower bridge arm can be kept open. The upper and lower bridge arms of the half-bridge inverter circuit of the other two-thirds of the pulse voltage superposition unit are kept off. At this time, the equipment can be used as a high-voltage DC power supply with a rated specification of 80kV / 1000mA. The output current of the equipment can be adjusted by adjusting the inverter frequency of the inverter bridge on the primary side of the transformer.

[0032] Example 2 of the control method of the present invention:

[0033] For flue gas operating conditions requiring a base voltage superimposed on a pulse voltage, such as a power supply specification requiring a 60kV base DC voltage superimposed on a 60kV pulse voltage, n1 DC voltage superposition units provide the base voltage to first power the dust collector, establishing an electric field within the body. Using n2 pulse voltage superposition units as the carriers for providing the pulse voltage, the upper arm of the half-bridge inverter circuit is shut off, the lower arm of the half-bridge inverter circuit is opened and maintained for a period of time before being shut off. The pulse voltage units provide pulse energy to the load.

[0034] Due to the existence of parasitic equivalent capacitance of electrostatic precipitator, the tail of pulse voltage is long, resulting in excessive pulse width and air breakdown. The upper bridge arm of pulse voltage superposition unit can be opened one by one to recover the charge of parasitic equivalent capacitance of electrostatic precipitator to the filter capacitor in pulse voltage superposition unit, which not only reduces the pulse width but also saves electric energy. The output waveform after basic power supply is superimposed on pulse power supply is as follows: Figure 3 shown.

Claims

1. An energy-saving electrostatic precipitator high-voltage power supply, characterized by: The invention comprises a current limiting reactor (1), a rectifier unit (2), a high-frequency inverter unit (3), a high-frequency transformer (4), a DC voltage superposition unit (5) and a pulse voltage superposition unit (6) which are electrically connected in sequence; the high-frequency transformer (4) is a high-frequency transformer with a primary single winding and a secondary multi-winding structure, and the secondary multi-windings are n1+n2 groups; the DC voltage superposition unit (5) comprises n1 DC voltage circuits corresponding to a part of the secondary multi-windings, the input ends of the n1 DC voltage circuits are respectively connected to the output ends of the part of the secondary multi-windings, and the output ends are connected in sequence; the pulse voltage superposition unit (6) comprises n2 pulse voltage circuits corresponding to another part of the secondary multi-windings, the pulse voltage circuits are composed of a rectifier circuit, a filter circuit and a half-bridge inverter circuit, the input ends of the n2 pulse voltage circuits are respectively connected to the output ends of the other part of the secondary multi-windings, and the output ends are connected in sequence.

2. The energy-saving electrostatic precipitator high-voltage power supply according to claim 1, characterized in that: The positive output terminal of the DC voltage circuit is connected to the negative output terminal of the adjacent DC voltage circuit; the inverter output terminal of the pulse voltage circuit is connected to the positive electrode of the adjacent pulse voltage circuit.

3. The energy-saving electrostatic precipitator high-voltage power supply according to claim 2, characterized in that: The high-frequency transformer (4) is a single-phase transformer.

4. The energy-saving electrostatic precipitator high-voltage power supply according to claim 3, characterized in that: The DC voltage circuit is composed of a rectifier circuit and a filter circuit.

5. The energy-saving electrostatic precipitator high-voltage power supply according to claim 4, characterized in that: The rectifier circuit is a rectifier bridge circuit composed of diodes; the filter circuit is composed of energy storage capacitors; the half-bridge inverter circuit is composed of two IGBTs connected in series, and the two IGBTs respectively constitute the upper arm and the lower arm of the inverter half-bridge.

6. An energy-saving electrostatic precipitator high-voltage power supply according to any one of claims 1 to 5, characterized in that: The rectifier unit (2) comprises a rectifier bridge and a filter capacitor.

7. An energy-saving electrostatic precipitator high-voltage power supply according to any one of claims 1 to 5, characterized in that: The high-frequency inverter unit (3) is composed of a single-phase IGBT inverter bridge and a resonant capacitor.

8. A method for controlling an energy-saving electrostatic precipitator high-voltage power supply according to claim 5, characterized in that: By selecting the on / off combination of the upper and lower bridge arms of the half-bridge inverter circuit in the n2 pulse voltage circuits, the high-frequency transformer (4) can achieve an equivalent high-ratio DC voltage output, an equivalent low-ratio DC power supply output, and a DC voltage superimposed pulse voltage output.

9. The control method of the energy-saving electrostatic precipitator high-voltage power supply according to claim 8, characterized in that: By controlling the upper bridge arm of the inverter half-bridge in n2 pulse voltage circuits to be turned off and the lower bridge arm to be partially or fully turned on and kept in the turned-on state, the equivalent transformation ratio of the high-frequency transformer (4) is changed, so that the high-voltage power supply outputs a DC voltage of different voltage levels; the basic voltage is provided by n1 DC voltage circuits, and the upper bridge arm of the inverter half-bridge in n2 pulse voltage circuits is controlled to be turned off and the lower bridge arm to be partially or fully turned on, kept for a period of time and then turned off, to provide a DC voltage superimposed on the pulse voltage to the load; the lower bridge arm is kept turned off, and by controlling the opening of part of the upper bridge arm of the inverter half-bridge, the charge on the load parasitic capacitance after the pulse voltage is formed is returned to the filter capacitor of the DC voltage superposition unit and the pulse voltage superposition unit.

Images