CN111682579A - Single-phase harmonic resonance optimization suppression device and suppression method - Google Patents
Single-phase harmonic resonance optimization suppression device and suppression method Download PDFInfo
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- CN111682579A CN111682579A CN202010386933.4A CN202010386933A CN111682579A CN 111682579 A CN111682579 A CN 111682579A CN 202010386933 A CN202010386933 A CN 202010386933A CN 111682579 A CN111682579 A CN 111682579A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/01—Arrangements for reducing harmonics or ripples
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
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Abstract
The invention discloses a single-phase harmonic resonance optimization suppression device and a suppression method. In a distributed grid-connected power generation system, due to coupling influences among a plurality of parallel inverters and between an inverter and a power grid, the system has the risk of interactive resonance instability. According to the invention, the single-phase harmonic resonance optimization suppression device based on the low-voltage switching device is added at the PCC (point-to-point) end of the converter group, and the series-parallel connection unit and the parallel-connection unit work in a coordinated manner, so that the passivity of series-parallel connection impedance of the PCC end is expanded, the self-discipline stability range of the multi-parallel connection inverter group is improved, and the optimization suppression of harmonic resonance is realized.
Description
Technical Field
The invention belongs to the field of power electronics, and particularly relates to a single-phase harmonic resonance optimal suppression device and a suppression method.
Background
As the global energy crisis deepens, new energy distributed grid-connected power generation technology draws attention. Generally, in order to increase the capacity of the inverter for grid-connected power generation, the inverter is connected in parallel to the grid. Meanwhile, due to the existence of line impedance and power grid impedance, coupling phenomena exist among multiple parallel inverters and between the inverters and the power grid, and the coupling phenomena provide challenges for the stability and the output power quality of a grid-connected power generation system. In addition, series or parallel resonance is easily excited due to the presence of a large number of harmonic sources in the grid-connected power generation system. In a distributed grid-connected power generation system, the oscillation of an inverter may be caused by the occurrence of resonance, so that the stability of an inverter group is influenced, and the safe operation of a power system is endangered in serious cases, thereby causing the occurrence of power transmission and distribution accidents. Therefore, the present patent discloses a single-phase grid-connected power generation system in which a virtual damper is constructed in such a manner that an active converter is connected in series-parallel to a PCC terminal of an inverter group, thereby improving the dynamic steady-state characteristics of the system and achieving optimal suppression of harmonic resonance.
Disclosure of Invention
The invention provides a single-phase harmonic resonance optimization suppression device and a suppression method aiming at the defects of the prior art, and realizes the passivity expansion of series-parallel impedance of a PCC point and improves the stability range of the autonomy of an inverter group by constructing a topological structure of the coordinated operation of series-parallel units based on a low-voltage switch device at the PCC end of the inverter group.
A single-phase harmonic resonance optimization suppression device comprises a converter series unit and a converter parallel unit, and specifically comprises three bridge arms, a direct-current bus unit, an alternating-current filter inductor, an alternating-current filter capacitor and an interphase capacitor, wherein each bridge arm comprises two low-voltage controllable switching tubes, and one of the bridge arms is a common bridge arm; enabling the three bridge arms to form a series unit and a parallel unit;
the single-phase harmonic resonance optimization suppression device is positioned at a PCC (point of charge coupled device) end of an inverter group of the distributed grid-connected power generation system; two bridge arms of the series unit are connected with corresponding alternating current filter inductors and then are connected with the output end of the inverter group through alternating current filter capacitors; the midpoint of a non-common bridge arm in the parallel unit is connected with an interphase capacitor and is connected with a PCC (point-to-point capacitor) end of the inverter group, and the series unit and the parallel unit share one direct current bus unit;
the single-phase harmonic resonance optimization suppression device drives the series unit and the parallel unit to work coordinately through detecting harmonic resonance information in the system, achieves the effect of series or parallel virtual impedance, and achieves the passive expansion of PCC point impedance.
Preferably, the harmonic resonance optimization suppression device is based on a low-voltage switching device, and the main circuit topology structure of the harmonic resonance optimization suppression device comprises a bridge arm with series impedance remolded, a bridge arm with parallel impedance remolded and a common bridge arm with series and parallel impedance remolded.
Preferably, the direct current bus unit in the device is composed of an energy storage capacitor, and meanwhile, stable direct current voltage is provided for the operation of the series unit and the parallel unit.
Preferably, the low-voltage controllable switch tube adopts a MOSFET.
Preferably, two ends of the alternating current filter capacitor are connected with a bidirectional protection switch in parallel, and the bidirectional protection switch adopts a reversible thyristor.
Preferably, the dc bus capacitor is an electrolytic capacitor.
Preferably, the filter inductance core is made of ferrite or amorphous.
Preferably, the filter capacitor and the interphase capacitor are both nonpolar thin film capacitors.
A suppression method of a single-phase harmonic resonance optimization suppression device specifically comprises the following steps:
step 1, detecting and extracting harmonic resonance information of a common node of a grid-connected power generation system;
step 2, evaluating the state of the resonance instability of the inverter group, and adjusting parameters and targets of harmonic resonance optimization suppression by combining with upper layer area coordination instructions;
step 3, driving each bridge arm to generate corresponding PWM signals to act on the switch tube through corresponding control strategies, and adjusting the working condition of the device at any time according to the system state;
step 4, when the autonomy of the inverter group is good or the interactive harmonic resonance between the inverters and the power grid is lower than a set threshold value, performing a harmonic voltage isolation control strategy by a series unit in the harmonic resonance optimization suppression device;
and 5, when the autonomy of the inverter group is not stable or the mutual harmonic resonance between the inverters and the power grid is higher than a set threshold value, the series units and the parallel units work in a coordinated mode, and the effect of remodeling series-parallel impedance is achieved.
Compared with the prior art, the single-phase harmonic resonance optimization suppression device has the advantages that: the single-phase harmonic resonance optimization suppression device is suitable for harmonic resonance suppression of a regional inverter group, achieves the effect of series or parallel virtual impedance through the coordinated work of the series-parallel units, realizes the passive expansion of series-parallel impedance of the PCC points, is combined with high-frequency harmonic resonance treatment of the inverter units, and ensures the dynamic and steady-state characteristics of the system.
Drawings
Fig. 1 is a topological diagram of a specific circuit of the single-phase harmonic resonance optimization suppression device.
Fig. 2 is a schematic diagram of the apparatus control.
Fig. 3 is a diagram of a grid-connected structure of an inverter group.
Detailed Description
The embodiments of the present invention will be further explained with reference to the drawings and examples, but the scope of the present invention is not limited thereto. It is noted that processes or symbols that are not specifically described in detail are understood and implemented by those skilled in the art with reference to the prior art.
Fig. 1 is a topological diagram of a specific circuit of a single-phase harmonic resonance optimization suppression device. The device is positioned at a PCC (programmable logic controller) end of an inverter group and consists of a series unit and a parallel unit, and the series unit and the parallel unit share one direct current bus.
The specific connection mode of the circuit is as follows: the main circuit comprises three bridge arms a, b and c, wherein the bridge arm b is a common bridge arm of a series unit and a parallel unit, and each bridge arm comprises two controllable switching tubes. The series unit and the parallel unit share one direct current bus, and the direct current bus has a capacitance of C3 and is responsible for the supply of the full-bridge direct current voltage source. The series connection unit comprises an a bridge arm and a b bridge arm, wherein the midpoint of the a bridge arm is connected with an alternating current filter inductor L1, the midpoint of the b bridge arm is connected with an alternating current filter inductor L2, the a bridge arm and the b bridge arm are respectively connected with corresponding inductors and then are connected with the output end of the inverter group through an alternating current filter capacitor C1, and the bidirectional protection switch is connected in parallel with the two ends of the alternating current filter capacitor C1; the parallel unit comprises a C-bridge arm and a b-bridge arm, wherein the midpoint of the C-bridge arm is connected with the PCC (capacitor C2) of the inverter group through a capacitor C2.
Fig. 2 is a schematic diagram of the apparatus control, in which thin lines indicate sampling lines. The series unit is connected with the output end of the inverter group through a capacitor, and the parallel unit is connected with the PCC end of the inverter group through a capacitor. Harmonic resonance information of the common node is extracted, the state of resonance instability of the inverter group is evaluated, parameters and targets of harmonic resonance optimization suppression are adjusted in combination with upper-layer coordination demand instructions, and then the bridge arms are driven to generate corresponding PWM signals to act on bridge arm switching tubes through corresponding control strategies, so that the series units and the parallel units are driven to work coordinately. The working condition of the device can be adjusted at any time according to the system state: when the autonomy of the inverter group is good or the interactive harmonic resonance between the inverters and the power grid is light, a harmonic voltage isolation control strategy is carried out by a series unit in the harmonic resonance optimization suppression device, so that the capability of the inverter group for resisting the power grid disturbance is improved; when the autonomy of the inverter group is stable and lacking or the interactive harmonic resonance between the inverters and the power grid is serious, the series units and the parallel units work in a coordinated mode, the effect of remodeling series-parallel impedance is achieved, and the interactive harmonic resonance is restrained. The bidirectional switch in the device plays a role in protection, and when the single-phase mutual resonance suppression device fails, the bidirectional switch plays a role in protection by closing the switch. Fig. 3 is a schematic diagram of the connection between the device and the single-phase grid-connected power generation system.
Because the added series-parallel converter bridge arm only processes high-frequency harmonic resonance and is not responsible for regulating fundamental wave power, the rated volt-ampere value of the added device is very low. And secondly, as most of the power grid voltage is borne by the capacitor C2, the semiconductor switching devices of the series-parallel bridge arms can adopt low-voltage switching devices, and the cost is lower.
Therefore, the harmonic resonance information in the single-phase grid-connected power generation system can be timely and effectively detected and optimized suppression can be realized through the coordinated work of the series units and the parallel units. In addition, by evaluating the stable state and the interaction degree of the inverter group in the system, the invention can adjust the working mode of the inverter group, and the efficiency is improved while the harmonic resonance is optimized and restrained. Meanwhile, the protection function provided by the device provides redundancy protection for the safe operation of the system.
It should be noted that the above embodiments are only used for illustrating the present invention, and do not limit the technical solutions described in the present invention; meanwhile, although the present invention has been described in detail with reference to the above embodiments, it will be understood by those skilled in the art that the present invention may be modified and equivalents may be substituted; therefore, all technical solutions and modifications which do not depart from the spirit and scope of the present invention should be construed as being included in the scope of the appended claims.
Claims (9)
1. A single-phase harmonic resonance optimization suppression device is characterized in that: the converter comprises a converter series unit and a converter parallel unit, and specifically comprises three bridge arms, a direct-current bus unit, an alternating-current filter inductor, an alternating-current filter capacitor and an interphase capacitor, wherein each bridge arm comprises two low-voltage controllable switching tubes, and one of the bridge arms is a common bridge arm; enabling the three bridge arms to form a series unit and a parallel unit;
the single-phase harmonic resonance optimization suppression device is positioned at a PCC (point of charge coupled device) end of an inverter group of the distributed grid-connected power generation system; two bridge arms of the series unit are connected with corresponding alternating current filter inductors and then are connected with the output end of the inverter group through alternating current filter capacitors; the midpoint of a non-common bridge arm in the parallel unit is connected with an interphase capacitor and is connected with a PCC (point-to-point capacitor) end of the inverter group, and the series unit and the parallel unit share one direct current bus unit;
the single-phase harmonic resonance optimization suppression device drives the series unit and the parallel unit to work coordinately through detecting harmonic resonance information in the system, achieves the effect of series or parallel virtual impedance, and achieves the passive expansion of PCC point impedance.
2. The single-phase harmonic resonance optimal suppression device according to claim 1, characterized in that: the harmonic resonance optimization suppression device is based on a low-voltage switch device, and the main circuit topological structure of the harmonic resonance optimization suppression device comprises a bridge arm with series impedance remodeling, a bridge arm with parallel impedance remodeling and a common bridge arm with series and parallel impedance remodeling.
3. The single-phase harmonic resonance optimal suppression device according to claim 1, characterized in that: a direct current bus unit in the device is composed of an energy storage capacitor and provides stable direct current voltage for the work of the series unit and the parallel unit.
4. The single-phase harmonic resonance optimal suppression device according to claim 1, characterized in that: the low-voltage controllable switch tube adopts MOSFET.
5. The single-phase harmonic resonance optimal suppression device according to claim 1, characterized in that: two ends of the alternating current filter capacitor are connected with a bidirectional protection switch in parallel, and the bidirectional protection switch adopts a reversible thyristor.
6. The single-phase harmonic resonance optimal suppression device according to claim 1, characterized in that: the direct current bus capacitor is an electrolytic capacitor.
7. The single-phase harmonic resonance optimal suppression device according to claim 1, characterized in that: the filter inductance magnetic core is made of ferrite or amorphous.
8. The single-phase harmonic resonance optimal suppression device according to claim 1, characterized in that: and the filter capacitor and the interphase capacitor are both nonpolar film capacitors.
9. The suppression method of the single-phase harmonic resonance optimal suppression device according to claim 1, characterized in that: the method specifically comprises the following steps:
step 1, detecting and extracting harmonic resonance information of a common node of a grid-connected power generation system;
step 2, evaluating the state of the resonance instability of the inverter group, and adjusting parameters and targets of harmonic resonance optimization suppression by combining with upper layer area coordination instructions;
step 3, driving each bridge arm to generate corresponding PWM signals to act on the switch tube through corresponding control strategies, and adjusting the working condition of the device at any time according to the system state;
step 4, when the autonomy of the inverter group is good or the interactive harmonic resonance between the inverters and the power grid is lower than a set threshold value, performing a harmonic voltage isolation control strategy by a series unit in the harmonic resonance optimization suppression device;
and 5, when the autonomy of the inverter group is not stable or the mutual harmonic resonance between the inverters and the power grid is higher than a set threshold value, the series units and the parallel units work in a coordinated mode, and the effect of remodeling series-parallel impedance is achieved.
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Citations (5)
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| US4812669A (en) * | 1986-06-26 | 1989-03-14 | Mitsubishi Denki Kabushiki Kaisha | Harmonic suppressing device |
| KR20110129043A (en) * | 2010-05-25 | 2011-12-01 | 고은순 | A electrical energy saver with improved power quality |
| CN104836229A (en) * | 2015-05-28 | 2015-08-12 | 武汉大学 | Global resonance inhibition device and method of multi grid-connected inverter system based on virtual impedance |
| CN108173288A (en) * | 2018-02-09 | 2018-06-15 | 合肥工业大学 | Inhibit the voltage-type impedance adapter control method of multi-inverter grid-connected system resonance |
| CN108322023A (en) * | 2018-03-20 | 2018-07-24 | 西安许继电力电子技术有限公司 | A kind of photovoltaic combining inverter resonance suppression circuit and its suppressing method |
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2020
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Patent Citations (5)
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|---|---|---|---|---|
| US4812669A (en) * | 1986-06-26 | 1989-03-14 | Mitsubishi Denki Kabushiki Kaisha | Harmonic suppressing device |
| KR20110129043A (en) * | 2010-05-25 | 2011-12-01 | 고은순 | A electrical energy saver with improved power quality |
| CN104836229A (en) * | 2015-05-28 | 2015-08-12 | 武汉大学 | Global resonance inhibition device and method of multi grid-connected inverter system based on virtual impedance |
| CN108173288A (en) * | 2018-02-09 | 2018-06-15 | 合肥工业大学 | Inhibit the voltage-type impedance adapter control method of multi-inverter grid-connected system resonance |
| CN108322023A (en) * | 2018-03-20 | 2018-07-24 | 西安许继电力电子技术有限公司 | A kind of photovoltaic combining inverter resonance suppression circuit and its suppressing method |
Non-Patent Citations (2)
| Title |
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| YAOWEI HU等: "Current Harmonic Suppression for Grid-Connected VSG Based on Virtual Harmonic Impedance", 《2019 10TH INTERNATIONAL CONFERENCE ON POWER ELECTRONICS AND ECCE ASIA(ICPE 2019 - ECCE ASIA)》 * |
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