CN106788591B - Photovoltaic grid-connected system based on power line carrier communication - Google Patents
Photovoltaic grid-connected system based on power line carrier communication Download PDFInfo
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- CN106788591B CN106788591B CN201611020709.3A CN201611020709A CN106788591B CN 106788591 B CN106788591 B CN 106788591B CN 201611020709 A CN201611020709 A CN 201611020709A CN 106788591 B CN106788591 B CN 106788591B
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Abstract
The application discloses photovoltaic grid-connected system based on power line carrier communication specifically is: each device which needs to perform power line carrier communication is provided with a power line carrier communication module in the direct current side device of the photovoltaic grid-connected system and the photovoltaic inverter; and one connecting terminal of each power line carrier communication module is grounded, and the other connecting terminal is connected with the positive pole or the negative pole of the equipment corresponding to the power line carrier communication module. The reliability of power line carrier communication of the direct current side of the photovoltaic grid-connected system is improved.
Description
Technical Field
The invention relates to the technical field of photovoltaic power generation, in particular to a photovoltaic grid-connected system based on power line carrier communication.
Background
Power line carrier communication (hereinafter abbreviated as PLC) is a communication method specific to a power system. The PLC is a communication technology using a power line as a transmission medium of a high-frequency carrier signal, and has a greatest characteristic that data can be transmitted only by the power line without newly erecting a network.
The application of the PLC technology to the dc side of the photovoltaic grid-connected system is shown in fig. 1, and the specific analysis is as follows: the photovoltaic grid-connected system is that direct current generated by the photovoltaic module 100 is converted into alternating current meeting the requirements of a commercial power grid through the photovoltaic inverter 200 and then is connected to a public power grid. In a high-power photovoltaic grid-connected system, a junction device such as a dc junction box 300 is often required to be configured. The application of the PLC technology to the dc side of the pv grid-connected system means that a PLC module is configured for each device that needs to perform power line carrier communication in the dc side devices (such as the pv modules 100 and the dc combiner box 300) of the pv grid-connected system and the pv inverter 200, and each PLC module is connected to the positive and negative electrodes of the device corresponding to the PLC module by two terminals, so that the PLC module can couple the high-frequency carrier signal to be transmitted to the positive and negative power lines for transmission.
However, since a large filter capacitor C is connected across the positive electrode and the negative electrode of the dc side of the photovoltaic inverter 200, the high-frequency carrier signal will be greatly absorbed, so that the PLC modules (such as the PLC modules in the photovoltaic inverter 200 and the dc combiner box 300) near the filter capacitor C cannot reliably communicate with other PLC modules at all.
Disclosure of Invention
In view of this, the invention provides a photovoltaic grid-connected system based on power line carrier communication, so as to improve reliability of power line carrier communication at a direct current side of the photovoltaic grid-connected system.
A photovoltaic grid-connected system based on power line carrier communication, wherein:
each device which needs to perform power line carrier communication is provided with a power line carrier communication module in the direct current side device of the photovoltaic grid-connected system and the photovoltaic inverter;
and one connecting terminal of each power line carrier communication module is grounded, and the other connecting terminal is connected with the positive pole or the negative pole of the equipment corresponding to the power line carrier communication module.
Wherein, a binding post ground connection of every power line carrier communication module includes:
and one wiring terminal of each power line carrier communication module is directly connected with the ground through a metal frame, a metal shell or a metal bracket of the equipment corresponding to the power line carrier communication module.
Wherein, a binding post ground connection of every power line carrier communication module includes:
and one wiring terminal of each power line carrier communication module is connected with the ground through a copper bar.
The photovoltaic inverter establishes communication with other equipment through a power line carrier communication module corresponding to the photovoltaic inverter and a power line carrier communication module corresponding to the other equipment, and monitors the running state of the other equipment.
Wherein, the monitoring the operation state of the other devices comprises:
each photovoltaic module uploads the state information of the photovoltaic module to the photovoltaic inverter, and when the photovoltaic inverter finds that the photovoltaic module operates abnormally, the photovoltaic module which operates abnormally is turned off.
The direct-current side equipment of the photovoltaic grid-connected system comprises a plurality of photovoltaic modules.
The direct-current side equipment of the photovoltaic grid-connected system comprises a direct-current combiner box and a plurality of photovoltaic modules.
According to the technical scheme, the PLC module couples the high-frequency carrier signal to the positive power line (or the negative power line) and the ground line for transmission, and the filter capacitor C is not connected between the two transmission lines in a bridging manner, so that the problem that the transmission quality of the carrier communication of the power lines is influenced because the high-frequency carrier signal is greatly absorbed by the filter capacitor C does not exist. In addition, the coupling mode provided by the invention can also filter the low-frequency component on the positive power line (or the negative power line) and reserve the high-frequency component by utilizing the characteristic of high-frequency and low-frequency passing resistance of the filter capacitor C, thereby further improving the transmission quality of power line carrier communication.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a photovoltaic grid-connected system based on power line carrier communication disclosed in the prior art;
fig. 2 is a schematic structural diagram of a photovoltaic grid-connected system based on power line carrier communication according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of the system of fig. 2 when the grid-connected photovoltaic system has only 3 photovoltaic modules.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 2, an embodiment of the present invention discloses a photovoltaic grid-connected system based on power line carrier communication, so as to improve reliability of power line carrier communication at a dc side of the photovoltaic grid-connected system, specifically:
in the devices of the photovoltaic grid-connected system, namely the direct-current side device and the photovoltaic inverter 200, each device needing power line carrier communication is provided with a PLC module;
further, one connection terminal of each PLC module is grounded, and the other connection terminal is connected to the positive or negative electrode of the device corresponding to the PLC module (for convenience of description, the grounded connection terminal is defined as a "first connection terminal" and the other connection terminal is defined as a "second connection terminal" in the two connection terminals of the PLC module).
Wherein, the second binding post of every PLC module connects the positive pole or the negative pole with the equipment that this PLC module corresponds, indicates: the second wiring terminal of each PLC module is connected with the anode of the equipment corresponding to the PLC module; or the second wiring terminal of each PLC module is connected with the cathode of the equipment corresponding to the PLC module; or the second wiring terminals of a part of the PLC modules are connected with the anode of the equipment corresponding to the PLC module, and the second wiring terminals of the other PLC modules are connected with the cathode of the equipment corresponding to the PLC module. Fig. 2 is an example in which the second connection terminal of each PLC module is connected to the positive electrode of the device corresponding to the PLC module.
In a high-power photovoltaic grid-connected system, direct-current side equipment of the photovoltaic grid-connected system comprises a direct-current junction box and a plurality of photovoltaic modules; in medium and low power photovoltaic grid-connected systems, the dc-side equipment of the photovoltaic grid-connected system includes a plurality of photovoltaic modules, but usually no dc combiner box is provided. Fig. 2 is only an example of a high-power photovoltaic grid-connected system.
Wherein, the first binding post ground connection of every PLC module, can be that the first binding post of every PLC module corresponds through this PLC module the metal frame of equipment, metal casing or metal support directly link to each other with the ground, also can be that the first binding post of every PLC module passes through the copper bar and links to each other with the ground, also can be that the first binding post of every PLC module directly links to each other with the ground, also can be other ground connection modes, and is not limited.
By comparing this embodiment with the prior art, it can be seen that:
in the prior art, a high-frequency carrier signal is coupled to a positive power line and a negative power line for transmission, but in this coupling mode, a very large filter capacitor C is connected across a positive electrode and a negative electrode of a direct-current side of the photovoltaic inverter 200, that is, a very large filter capacitor C is connected across two transmission lines, and the filter capacitor C can greatly absorb the high-frequency carrier signal, so that the transmission quality of power line carrier communication is affected.
In the embodiment, the high-frequency carrier signal is coupled to the positive power line (or the negative power line) and the ground line for transmission, and the filter capacitor C is not bridged between the two transmission lines, so that the problem that the transmission quality of the carrier communication of the power lines is affected because the high-frequency carrier signal is greatly absorbed by the filter capacitor C does not exist.
Furthermore, since the filter capacitor C has the characteristic of passing high frequency and low frequency, in the coupling method provided in this embodiment, the filter capacitor C is equivalent to a path for the high frequency carrier signal transmitted from the power line of the positive stage (or the power line of the negative stage), for example: assuming that the number of the photovoltaic modules 100 in fig. 2 is 3, the photovoltaic modules are respectively photovoltaic module # 1, photovoltaic module # 2 and photovoltaic module # 3 which are connected in series between the positive electrode and the negative electrode of the dc combiner box 300, as shown in fig. 3; when a PLC module (A for short) corresponding to the photovoltaic module # 2 transmits a high-frequency carrier signal to a PLC module (B for short) corresponding to the direct current combiner box 300, the high-frequency carrier signal transmitted from the second connecting terminal of the A is transmitted to the second connecting terminal of the B in two directions, and one direction is transmitted to the second connecting terminal of the B sequentially through the anode of the photovoltaic module # 2, the cathode of the photovoltaic module # 1, the anode of the photovoltaic module # 1 and the anode of the direct current combiner box 300; the other direction is that the high-frequency carrier wave passes through the anode of the photovoltaic module # 2, the cathode of the photovoltaic module # 2, the anode of the photovoltaic module # 3, the cathode of the direct current combiner box 300, the filter capacitor C and the anode of the direct current combiner box 300 in sequence and is transmitted to the second connecting terminal of the B, and the filter capacitor C is equivalent to a passage for the high-frequency carrier wave signal. Therefore, the coupling method of the present embodiment can also filter the low frequency component on the positive power line (or negative power line) and retain the high frequency component by utilizing the characteristic of the filter capacitor C passing high frequency and low frequency, thereby further improving the transmission quality of the power line carrier communication.
Optionally, in the power line carrier communication process, the photovoltaic inverter 200 establishes communication with other devices through the PLC module corresponding to the photovoltaic inverter 200 and the PLC modules corresponding to the other devices, so as to monitor the operating states of the other devices. For example: each photovoltaic module 100 uploads state information (such as voltage, current, temperature information, etc.) of itself to the photovoltaic inverter 200, and when the photovoltaic inverter 200 finds that the photovoltaic module is abnormal in operation, the photovoltaic module with abnormal operation is turned off.
In summary, the PLC module in the present invention couples the high-frequency carrier signal to the positive power line (or the negative power line) and the ground line for transmission, and there is no filter capacitor C connected across between the two transmission lines, so that there is no problem that the transmission quality of the power line carrier communication is affected because the high-frequency carrier signal is greatly absorbed by the filter capacitor C. In addition, the coupling mode provided by the invention can also filter the low-frequency component on the positive power line (or the negative power line) and reserve the high-frequency component by utilizing the characteristic of high-frequency and low-frequency passing resistance of the filter capacitor C, thereby further improving the transmission quality of power line carrier communication.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the embodiments. Thus, the present embodiments are not intended to be limited to the embodiments shown herein but are to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (5)
1. A photovoltaic grid-connected system based on power line carrier communication, wherein:
the direct-current side equipment of the photovoltaic grid-connected system comprises a plurality of photovoltaic modules which are sequentially connected in series to form a photovoltaic group string, and the photovoltaic group strings are connected in parallel to a photovoltaic inverter; or the direct-current side equipment of the photovoltaic grid-connected system comprises a direct-current combiner box and a plurality of photovoltaic modules, the photovoltaic modules are sequentially connected in series to form a photovoltaic group string, and the photovoltaic group string is connected to the photovoltaic inverter through the direct-current combiner box;
the method is characterized in that:
each device which needs to perform power line carrier communication is provided with a power line carrier communication module in the direct current side device of the photovoltaic grid-connected system and the photovoltaic inverter;
and the first connecting terminal of each power line carrier communication module is grounded, the second connecting terminal is connected with the anode or the cathode of the equipment corresponding to the power line carrier communication module, a high-frequency carrier signal sent by the second connecting terminal of one equipment is transmitted to the second connecting terminal of the other equipment in two directions, and a filter capacitor connected between the anode and the cathode of the direct current side of the photovoltaic inverter in one direction.
2. The grid-connected photovoltaic system according to claim 1, wherein one connection terminal of each power line carrier communication module is grounded, and the system comprises:
and one wiring terminal of each power line carrier communication module is directly connected with the ground through a metal frame, a metal shell or a metal bracket of the equipment corresponding to the power line carrier communication module.
3. The grid-connected photovoltaic system according to claim 1, wherein one connection terminal of each power line carrier communication module is grounded, and the system comprises:
and one wiring terminal of each power line carrier communication module is connected with the ground through a copper bar.
4. The grid-connected photovoltaic system according to claim 1, wherein the photovoltaic inverter establishes communication with other devices through a power line carrier communication module corresponding to the photovoltaic inverter and a power line carrier communication module corresponding to the other devices, and monitors the operating states of the other devices.
5. The grid-connected PV system of claim 4, wherein the monitoring the operating status of the other devices comprises:
each photovoltaic module uploads the state information of the photovoltaic module to the photovoltaic inverter, and when the photovoltaic inverter finds that the photovoltaic module operates abnormally, the photovoltaic module which operates abnormally is turned off.
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| CN107483083A (en) * | 2017-09-14 | 2017-12-15 | 保定英利分布式能源股份有限公司 | Photovoltaic system monitoring method based on power line carrier communication |
| CN109802489B (en) * | 2019-01-25 | 2020-08-28 | 温州职业技术学院 | Solar photovoltaic panel measurement and control communication system based on power line carrier |
| CN110572184B (en) * | 2019-08-02 | 2021-03-05 | 华为技术有限公司 | Power generation system and communication device for power generation system |
| CN112165343B (en) * | 2020-09-25 | 2021-10-22 | 合肥阳光新能源科技有限公司 | High-frequency communication device, high-frequency carrier transmission direction control method, device and medium |
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| CN103986182A (en) * | 2014-01-21 | 2014-08-13 | 云南师范大学 | Photovoltaic grid connected system based on power line carrier communication |
| CN104967214A (en) * | 2015-06-04 | 2015-10-07 | 南京理工大学 | Micro-grid system based on VACON industrial inverters |
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| CN102830317B (en) * | 2012-09-18 | 2016-09-07 | 国网山东省电力公司济宁供电公司 | A kind of distributed power generation dispersity monitoring device |
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| CN103986182A (en) * | 2014-01-21 | 2014-08-13 | 云南师范大学 | Photovoltaic grid connected system based on power line carrier communication |
| CN104967214A (en) * | 2015-06-04 | 2015-10-07 | 南京理工大学 | Micro-grid system based on VACON industrial inverters |
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