CN210957805U - Photovoltaic power system based on superconducting current limiter - Google Patents

Photovoltaic power system based on superconducting current limiter Download PDF

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CN210957805U
CN210957805U CN201921425406.9U CN201921425406U CN210957805U CN 210957805 U CN210957805 U CN 210957805U CN 201921425406 U CN201921425406 U CN 201921425406U CN 210957805 U CN210957805 U CN 210957805U
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photovoltaic power
current limiter
transformer
load
current
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刘莹
程媛
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Nanjing University of Science and Technology
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Nanjing University of Science and Technology
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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
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers
    • 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
    • Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment

Abstract

The utility model discloses a photovoltaic power system based on superconductive current limiter, its constitution includes: photovoltaic power generation system (1), first step-up transformer (2), second step-up transformer (4), superconductive current limiter (3), electric wire netting (5), load (6), the electric energy that photovoltaic power generation system (1) sent passes through first step-up transformer (2) and inserts load (6) at 01, 02 and 03 points respectively, install superconductive current limiter (3) additional before load (6), load (6) consume remaining electric energy and step up input to electric wire netting (5) once more through second step-up transformer (4). The technical effects of the utility model: the high-temperature superconducting current limiter has the characteristics of quick action time, automatic triggering, automatic resetting, continuous action and the like. The resistor type current limiter is arranged at a proper position, can effectively limit short-circuit fault current and has good current limiting effect. The stability of a photovoltaic power system is improved, and the power quality of a power grid is improved.

Description

Photovoltaic power system based on superconducting current limiter
Technical Field
The utility model relates to a photovoltaic power technology field, concretely relates to contain photovoltaic power system of resistive superconducting current limiter.
Background
With the progress of environmental protection and society, the distributed power generation gradually replaces the traditional thermal power generation, has simple power generation process, no mechanical rotating part, no fuel consumption, no emission of any substance including greenhouse gas, no noise and no pollution; the solar energy resources are widely distributed and inexhaustible. However, the photovoltaic power generation-compatible smart grid has the disadvantages of low energy density, low conversion efficiency, intermittent operation and great influence of climate environmental factors, and a conventional current limiting method cannot be simply adopted when various short-circuit faults occur in the photovoltaic power generation-compatible smart grid.
On the premise of considering both the cost of compressing and constructing a strong power grid and improving the economic stability of the operation of a power system, the standard specification of various rated parameters of power equipment can be well reduced by reducing the impact value of various short-circuit fault currents. Compared with the traditional current limiter, the high-temperature superconducting current limiter has the advantages of low investment cost, simple operation and obvious current limiting effect, and meets the current basic national conditions and the requirements for building a smart grid.
The application of the high-temperature superconducting current limiter in the photovoltaic power generation system provides very positive significance
SUMMERY OF THE UTILITY MODEL
The utility model discloses an above-mentioned technical problem is solved through following technical scheme:
a superconducting current limiter-based photovoltaic power system, comprising: the power generation system comprises a photovoltaic power generation system 1, a first boosting transformer 2, a second boosting transformer 4, a superconducting current limiter 3, a power grid 5 and a load 6, wherein electric energy generated by the photovoltaic power generation system 1 is connected to the load 6 through the first boosting transformer 2 at O1, O2 and O3 respectively, the superconducting current limiter 3 is additionally arranged in front of the load 6, and the rest electric energy consumed by the load 6 is input to the power grid through the second boosting transformer 4 in a boosting mode again.
The superconducting current limiter 3 comprises the following components: liquid nitrogen, a cryostat, a current continuous wire, a current lead, a superconducting current limiting element, a superconducting current limiting module, a linear coil and a current transformer.
The superconducting current-limiting module is connected with the secondary side of the current transformer in series, and the linear coil is connected with the primary side of the current transformer in series after being connected in parallel.
The photovoltaic power generation system 1 comprises the following components: the solar energy battery, the battery, controller and the inverter.
The inverter adopts a three-phase three-level inverter.
The utility model discloses there is following positive technological effect:
the high-temperature superconducting current limiter has the characteristics of quick action time, automatic triggering, automatic resetting, continuous action and the like. The action time of the device is generally about dozens of microseconds, and then the short-circuit current can be rapidly reduced to a limit value quickly, so that the stability of a power system is ensured. The current limiter can detect, convert and limit current, can stably operate under high voltage, and can pass large current but present extremely low impedance when a system is normal, and can be ignored; the super-impedance is presented only when the system has short-circuit fault, and the limiting effect on the short-circuit current is very obvious, so that the high-temperature superconducting current limiter is one of the ideal short-circuit fault limiting devices at present.
The resistor type current limiter is arranged at a proper position, can effectively limit short-circuit fault current and has good current limiting effect. The stability of a photovoltaic power system is improved, and the power quality of a power grid is improved.
Drawings
Fig. 1 is a diagram of a photovoltaic power system based on a superconducting current limiter.
Fig. 2 is a schematic block diagram of a magnetic field assisted resistive current limiter.
Fig. 3 is a circuit diagram of a magnetic field assisted resistive current limiter.
FIG. 4 is a three-phase three-level inverter topology structure diagram
In the figure: the photovoltaic power generation system is characterized in that 1 is a photovoltaic power generation system, 2 is a first step-up transformer, 3 is a superconducting current limiter, 4 is a second step-up transformer, 5 is a power grid and 6 is a load.
Detailed Description
The following description will further describe embodiments of the present invention with reference to the accompanying drawings.
1. Photovoltaic power system integral implementation scheme based on superconducting current limiter
A superconducting current limiter-based photovoltaic power system, comprising: the power generation system comprises a photovoltaic power generation system 1, a boosting transformer 2, a boosting transformer 4, a superconducting current limiter 3, a power grid 5 and a load 6, wherein electric energy generated by the photovoltaic power generation system 1 is respectively connected to the load 6 at O1, O2 and O3 through the boosting transformer 2, the superconducting current limiter 3 is additionally arranged in front of the load 6, and the rest electric energy consumed by the load 6 is boosted again and input to the power grid through the boosting transformer 4. As shown in fig. 1.
The superconducting current limiter 3 comprises the following components: liquid nitrogen, a cryostat, a current continuous wire, a current lead, a superconducting current limiting element, a superconducting current limiting module, a linear coil and a current transformer. As shown in fig. 2.
The superconducting current-limiting module is connected with the secondary side of the current transformer in series, and the linear coil is connected with the primary side of the current transformer in series after being connected in parallel. As shown in fig. 3.
The photovoltaic power generation system 1 comprises the following components: the solar energy battery, the battery, controller and the inverter.
The inverter adopts a three-phase three-level inverter. As shown in fig. 4.
2. Photovoltaic power generation system
A photovoltaic power generation system refers to a power generation system that directly converts light energy into electric energy without a thermal process. Its main components are solar cell, accumulator, controller and inverter. The device has the characteristics of high reliability, long service life, no environmental pollution, independent power generation and grid-connected operation.
Consists of the following components: high concentration photovoltaic systems (HCPV) also include a light concentrating portion (typically a concentrating lens or mirror). The photovoltaic power generation system has the following functions:
(1) a photovoltaic Array (PV Array) is a photovoltaic Array, which is a direct current power generation unit formed by assembling a plurality of photovoltaic modules or photovoltaic panels together in a certain way and having a certain supporting structure, wherein under the condition of illumination (no matter sunlight or illumination generated by other illuminants), a battery absorbs light energy, and accumulation of charges with different signs appears at two ends of the battery, namely "photovoltage" is generated. This is the "photovoltaic effect". Under the action of photovoltaic effect, the two ends of the solar cell generate electromotive force to convert light energy into electric energy to complete energy conversion
(2) The storage battery pack (optional) has the functions of storing electric energy generated by a solar cell matrix when being illuminated and supplying power to a load at any time, and the basic requirements of the storage battery pack for solar cell power generation are that ① self-discharge rate is low, ② service life is long, ③ deep discharge capacity is strong, ④ charging efficiency is high, ⑤ is low in maintenance or free of maintenance, ⑥ working temperature range is wide, and ⑦ price is low.
(3) Battery controller (optional). A battery controller is a device that can automatically prevent overcharge and overdischarge of a battery. Since the number of cycles and the depth of discharge of the secondary battery are important factors for determining the service life of the secondary battery, a battery controller capable of controlling overcharge or overdischarge of the secondary battery is indispensable
(4) An inverter. An inverter is a device that converts direct current to alternating current. When the solar battery and the storage battery are direct current power supplies and the load is an alternating current load, the inverter which is indispensable can be divided into an off-grid inverter and a grid-connected inverter according to the operation mode. The off-grid inverter is used for an independently operating solar cell power generation system to supply power to a load. The grid-connected inverter is used for a solar cell power generation system which operates in a grid-connected mode. The inverter can be divided into a square wave inverter and a sine wave inverter according to the output waveform, has simple circuits and low manufacturing cost, but has large harmonic component, and is generally used for systems with the power of hundreds of watts or less and low requirements on harmonic. The sine wave inverter is high in cost, but can be applied to various loads.
(5) A tracking system. Compared with a solar photovoltaic power generation system in a certain fixed place, the solar photovoltaic power generation system has the advantages that the solar illumination angle changes all the time and at all times every day when the solar photovoltaic power generation system rises and falls all the year round every day, and the power generation efficiency can reach the optimal state only if the solar cell panel can face the sun all the time. In general, a sun tracking control system in the world needs to calculate the angle of the sun at different times of each day in a year according to information such as longitude and latitude of a placement point, and store the position of the sun at each time in the year into a PLC (programmable logic controller), a singlechip or computer software, namely, a computer data theory is adopted for realizing tracking by calculating the position of the sun. Data and setting of latitude and longitude regions of the earth are needed, once the device is installed, the device is inconvenient to move or assemble and disassemble, and the data must be reset and various parameters must be adjusted after the device is moved every time.
3. Two step-up transformers
The step-up transformer 2 and the step-up transformer 4 are two types of step-up transformers having different specifications.
The step-up transformer is used for instantly starting voltage, so that the manufacturers of the transformers which can effectively realize instant step-up in China are rare, the instant start step-up capability of the step-up transformer is strong, and the step-up effect is good. The difference lies in that the non-excitation voltage regulating switch does not have the capacity of switching gears with loads, because the tap changer has a short-time disconnection process in the process of switching gears, and the disconnection of load current can cause arcing between contacts to burn out the tap changer or short circuit, so the transformer has to be powered off during gear shifting. And therefore are typically used in transformers where voltage requirements are not very stringent and frequent gear shifting is not required.
An ac step-up transformer is a device for converting ac voltage, current and impedance, and when an ac current flows through a primary winding, an ac magnetic flux is generated in an iron core (or a magnetic core) to induce a voltage (or a current) in a secondary winding. The transformer consists of an iron core (or a magnetic core) and a coil, wherein the coil is provided with two or more than two windings, the winding connected with a power supply is called a primary coil, and the other windings are called secondary coils. The AC step-up transformer has the characteristics of small volume, light weight, compact structure, complete functions, strong universality, convenient use and the like.
4. Magnetic field auxiliary resistance type current limiter
The improved resistance type of the quench of the superconducting element is guided by a magnetic field, a resistance type superconducting current limiter of an external winding is introduced, and the uniform quench of the superconductor is triggered and accelerated by magnetic field induction. The windings may be connected in series with the superconducting material by leads. When the superconducting material works normally, the current of the winding can induce to generate a stable and constant magnetic field which is parallel to the superconducting material, the value of the magnetic field is lower than the critical magnetic field value of the superconducting material, and the superconducting material is in a superconducting state; when a fault occurs, the fault current is larger than the critical current value, and the magnetic field induced by the fault current assists the critical current value of the superconducting material, so that uniform quench triggering is ensured, and a better current limiting effect is achieved. A schematic block diagram of a magnetic field assisted resistive current limiter, as shown in fig. 2; the magnetic field assisted resistive current limiter is shown in circuit alignment as shown in fig. 3. 5. Three-phase three-level inverter
As shown in fig. 3, the working principle is as follows: the NPC three-level inverter has four power switches per phase, and has three operating modes, taking phase a as an example: when T isa1、Ta2Conduction, Ta3、Ta4When the load is turned off, the potential at the point A is U regardless of the direction of the load currenta0＝Ud/2；
When T isa2、Ta3Conduction, Ta1、Ta4When the load current is in positive direction, O-D is formed when the load is turned off1-Ta2-a loop, the potential at point a being 0; when the load current is negative, O-D is formed1-Ta3-a loop, the potential at point a being 0;
when T isa3、Ta4Conduction, Ta1、Ta2When the load is turned off, the potential at the point A is U regardless of the direction of the load currenta0＝-UdThe operation mode is shown in table 1.
TABLE 1 NPC three-level inverter mode of operation
Figure DEST_PATH_GSB0000186966160000051

Claims (5)

1. A superconducting current limiter-based photovoltaic power system, comprising: photovoltaic power generation system (1), first step-up transformer (2), second step-up transformer (4), superconductive current limiter (3), electric wire netting (5), load (6), its characterized in that: electric energy generated by the photovoltaic power generation system (1) is respectively connected to a load (6) at points O1, O2 and O3 through a first step-up transformer (2), a superconducting current limiter (3) is additionally arranged in front of the load (6), and the rest electric energy consumed by the load (6) is input to a power grid (5) through a second step-up transformer (4) in a step-up mode.
2. A superconducting current limiter-based photovoltaic power system as claimed in claim 1 wherein: the superconducting current limiter (3) comprises the following components: liquid nitrogen, a cryostat, a current continuous wire, a current lead, a superconducting current limiting element, a superconducting current limiting module, a linear coil and a current transformer.
3. A superconducting current limiter-based photovoltaic power system according to claim 2, wherein: the superconducting current-limiting module is connected with the secondary side of the current transformer in series, and the linear coil is connected with the primary side of the current transformer in series after being connected in parallel.
4. A superconducting current limiter-based photovoltaic power system as claimed in claim 1 wherein: the photovoltaic power generation system (1) comprises the following components: the solar energy battery, the battery, controller and the inverter.
5. A superconducting current limiter-based photovoltaic power system according to claim 4, wherein: the inverter adopts a three-phase three-level inverter.
CN201921425406.9U 2019-08-29 2019-08-29 Photovoltaic power system based on superconducting current limiter Expired - Fee Related CN210957805U (en)

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Application Number Priority Date Filing Date Title
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