CN111049163A - Treatment method for three-phase imbalance generated by grid connection of single-phase distributed power supply - Google Patents
Treatment method for three-phase imbalance generated by grid connection of single-phase distributed power supply Download PDFInfo
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- CN111049163A CN111049163A CN201911214472.6A CN201911214472A CN111049163A CN 111049163 A CN111049163 A CN 111049163A CN 201911214472 A CN201911214472 A CN 201911214472A CN 111049163 A CN111049163 A CN 111049163A
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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
- H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase 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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
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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
- Y02E40/30—Reactive power compensation
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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
- Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks
Abstract
The invention relates to a management method for three-phase unbalance generated by grid connection of a single-phase distributed power supply, and belongs to the field of power grids. A current transformer CT is connected into a power supply loop of the single-phase distributed power supply to detect the grid-connected current in real time; sending the detected current to a controller for processing and analysis, calculating the current value required to be converted by each phase when the current reaches a balance state, and then sending a signal to an internal insulated gate bipolar transistor IGBT and driving the IGBT to act; the single-phase current is averagely divided into three parts, the phase angles of two parts of the current are changed and are superposed on other two phases, and finally, a three-phase balance state is achieved. The invention finds a method for treating three-phase imbalance generated during grid-connected power generation of a single-phase distributed power supply, can relieve impact current generated during grid connection, treat harmonic pollution in a system, stabilize three-phase voltage, guarantee power supply reliability and voltage qualification rate of a power distribution network, and improve the mastering capacity of managers on the single-phase distributed power supply.
Description
Technical Field
The invention belongs to the field of power grids, and relates to a method for treating three-phase imbalance generated by grid connection of a single-phase distributed power supply.
Background
The distributed energy system is relative to the traditional centralized energy system, which adopts large-capacity equipment and centralized production and then delivers various energies to a plurality of users in a larger range through special delivery facilities (a large power grid, a large heat supply network and the like); the distributed energy system is a medium and small energy conversion and utilization system which is directly oriented to users, can produce and supply energy on site according to the requirements of the users, has multiple functions and can meet multiple targets.
Distributed energy systems are increasingly emphasized in the world energy field due to the characteristics of flexible variable load, low initial investment, power supply reliability, small power transmission loss, suitability for renewable energy application and the like, and the investment of distributed energy is increased at present.
Distributed energy is various in types, when some single-phase distributed energy is connected to the grid, the low-voltage distribution network is unbalanced in three phases due to the unbalanced distribution and the tide characteristic, so that risks such as single-phase overload, unbalanced three-phase voltage and high single-phase voltage of power supply equipment are caused, and hidden dangers are brought to normal operation of the distribution network.
Disclosure of Invention
In view of the above, the present invention provides a method for treating three-phase imbalance generated by grid connection of a single-phase distributed power supply.
In order to achieve the purpose, the invention provides the following technical scheme:
the method for treating three-phase imbalance generated by grid connection of the single-phase distributed power supply comprises the steps of connecting a current transformer CT into a power supply loop of the single-phase distributed power supply, and detecting grid-connected current in real time;
sending the detected current to a controller for processing and analysis, calculating the current value required to be converted by each phase when the current reaches a balance state, and then sending a signal to an internal insulated gate bipolar transistor IGBT and driving the IGBT to act;
the single-phase current is averagely divided into three parts, the phase angles of two parts of the current are changed and are superposed on other two phases, and finally, a three-phase balance state is achieved.
Optionally, the current transformer CT is an electromagnetic current transformer or an electronic current transformer.
Optionally, the controller models are APF series and SVG series.
Optionally, the IGBT is 20N120CND, K25T120, G40N150D, 5GL40N150D, or G4PH50 UD.
Optionally, in the sending of the signal to the internal IGBT and driving the IGBT, when the distribution transformer is to compensate for an unbalanced current, the following principle should be satisfied:
the control of the current comprises the steps of compensating a power factor and adjusting the unbalance of three-phase current, and jointly determining reactive power required by compensation;
during actual engineering construction, a full-capacitive governing mode is adopted and is distinguished from inductance compensation, so that the condition of serious overcompensation is avoided;
the load is varied with time and the amount of compensation is adjusted in response to the variation in load.
Optionally, after the three-phase balanced state, the three-phase load is detected and adjusted.
The invention has the beneficial effects that: the method for treating the three-phase imbalance generated during grid-connected power generation of the single-phase distributed power supply is found, the impact current generated during grid connection and harmonic pollution in a treatment system can be relieved, the three-phase voltage is stabilized, the power supply reliability and the voltage qualification rate of the power distribution network are guaranteed, and the mastering capacity of managers on the single-phase distributed power supply is improved.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.
Drawings
For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:
fig. 1 is a schematic diagram of the principle of the present invention.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.
Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.
Fig. 1 shows a method for managing three-phase imbalance generated by grid connection of a single-phase distributed power supply.
The method for treating three-phase imbalance generated by grid connection of the single-phase distributed power supply comprises the steps of connecting a current transformer CT into a power supply loop of the single-phase distributed power supply, and detecting grid-connected current in real time;
sending the detected current to a controller for processing and analysis, calculating the current value required to be converted by each phase when the current reaches a balance state, and then sending a signal to an internal insulated gate bipolar transistor IGBT and driving the IGBT to act;
the single-phase current is averagely divided into three parts, the phase angles of two parts of the current are changed and are superposed on other two phases, and finally, a three-phase balance state is achieved.
The current transformer CT is an electromagnetic current transformer or an electronic current transformer.
The controller models are APF series and SVG series.
The IGBT is 20N120CND, K25T120, G40N150D, 5GL40N150D or G4PH50UD in model number.
1. Electromagnetic current transformer: the current transformer realizes current transformation according to the electromagnetic induction principle.
2. Electronic current transformer:
(1) the optical current transformer is characterized in that an optical device is used as a measured current sensor, and the optical device is composed of optical glass, all-fiber and the like.
(2) An air-core coil current transformer. Also known as Rogowski coil current transformers. The hollow coil is usually made by uniformly winding an enameled wire on an annular framework, the framework is made of non-ferromagnetic materials such as plastics, ceramics and the like, and the relative magnetic permeability of the framework is the same as that of air, which is a remarkable characteristic that the hollow coil is different from a current transformer with an iron core.
(3) A core-coil Low Power Current Transformer (LPCT). It is a development of the traditional electromagnetic current transformer. According to the design of high impedance resistance, the saturation characteristic is improved under very high primary current, the measurement range is expanded, the power consumption is reduced, the over-current and full-offset short-circuit current which can reach the short-circuit current can be measured without saturation with high accuracy, the measurement and protection can share one iron core coil type low-power current transformer, and the output of the transformer is a voltage signal.
APF series and SVG series products have three-phase unbalanced current correction function, and a column type compensation device LBC (load balancing device) for unbalanced correction and reactive compensation, which is a load balancing device, is developed specially. The three-phase load is balanced, the power quality of a power distribution network is improved, the utilization rate of a transformer is improved, and the line loss is reduced.
In the operation of sending a signal to the IGBT and driving it, when the distribution transformer is to compensate for unbalanced current, the following principle should be satisfied:
the control of the current comprises the steps of compensating a power factor and adjusting the unbalance of three-phase current, and jointly determining reactive power required by compensation;
during actual engineering construction, a full-capacitive governing mode is adopted and is distinguished from inductance compensation, so that the condition of serious overcompensation is avoided;
the load is varied with time and the amount of compensation is adjusted in response to the variation in load.
And after the three-phase balance state, detecting and adjusting the three-phase load.
The balance of the power cannot be absolute, but only relative balance can be achieved as far as possible, in the actual detection work, each department should take the established balance degree measurement index as a standard, professionally record and analyze the detection result, and regularly detect the load current of each phase so as to find out some three-phase imbalance conditions in time.
When the potential safety hazard is found in the detection process, the position needs to be adjusted and modified in time. For a part where no problem is found in the detection process, vigilance should also be increased. After the detection is finished, not only data sorting and analysis but also timely feedback is needed.
The feedback here mainly refers to the adjustment of three phases, which is inferred from the detection result, and the prediction of the possibility of the new technology being applied to the three phases. Through reasonable detection and deep analysis of detection results, the occurrence of imbalance can be avoided to the greatest extent, and the occurrence of power utilization accidents is reduced.
South German electric. The principle of the method is that current information is detected in real time through a CT (computed tomography), acquired information is sent to a DSP (digital signal processor) for analysis, current values required to be converted of all phases when the three-phase current reaches a balanced state are calculated, signals are sent to an internal IGBT (insulated gate bipolar translator) and driven to act, and three-phase unbalanced currents of a system are transferred and uniformly distributed, so that the three-phase currents reach the balanced state.
Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.
Claims (6)
1. The treatment method for generating three-phase unbalance by grid connection of the single-phase distributed power supply is characterized by comprising the following steps of:
a current transformer CT is connected into a power supply loop of the single-phase distributed power supply to detect the grid-connected current in real time;
sending the detected current to a controller for processing and analysis, calculating the current value required to be converted by each phase when the current reaches a balance state, and then sending a signal to an internal insulated gate bipolar transistor IGBT and driving the IGBT to act;
the single-phase current is averagely divided into three parts, the phase angles of two parts of the current are changed and are superposed on other two phases, and finally, a three-phase balance state is achieved.
2. The governance method for generating the three-phase imbalance of the single-phase distributed power supply grid-connected mode according to claim 1, is characterized in that: the current transformer CT is an electromagnetic current transformer or an electronic current transformer.
3. The governance method for generating the three-phase imbalance of the single-phase distributed power supply grid-connected mode according to claim 1, is characterized in that: the controller models are APF series and SVG series.
4. The governance method for generating the three-phase imbalance of the single-phase distributed power supply grid-connected mode according to claim 1, is characterized in that: the IGBT is 20N120CND, K25T120, G40N150D, 5GL40N150D or G4PH50UD in model number.
5. The governance method for generating the three-phase imbalance of the single-phase distributed power supply grid-connected mode according to claim 1, is characterized in that: in the operation of sending a signal to the IGBT and driving it, when the distribution transformer is to compensate for unbalanced current, the following principle should be satisfied:
the control of the current comprises the steps of compensating a power factor and adjusting the unbalance of three-phase current, and jointly determining reactive power required by compensation;
during actual engineering construction, a full-capacitive governing mode is adopted and is distinguished from inductance compensation, so that the condition of serious overcompensation is avoided;
the load is varied with time and the amount of compensation is adjusted in response to the variation in load.
6. The governance method for generating the three-phase imbalance of the single-phase distributed power supply grid-connected mode according to claim 1, is characterized in that: and after the three-phase balance state, detecting and adjusting the three-phase load.
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| CN201911214472.6A CN111049163A (en) | 2019-12-02 | 2019-12-02 | Treatment method for three-phase imbalance generated by grid connection of single-phase distributed power supply |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105375500A (en) * | 2015-11-25 | 2016-03-02 | 国家电网公司 | Three-phase unbalance monitoring and management system and method for distribution transformer |
| CN105429168A (en) * | 2015-11-05 | 2016-03-23 | 国网冀北电力有限公司张家口供电公司 | Electric energy quality treatment method based on AC/DC hybrid power supply network |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105429168A (en) * | 2015-11-05 | 2016-03-23 | 国网冀北电力有限公司张家口供电公司 | Electric energy quality treatment method based on AC/DC hybrid power supply network |
| CN105375500A (en) * | 2015-11-25 | 2016-03-02 | 国家电网公司 | Three-phase unbalance monitoring and management system and method for distribution transformer |
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