CN103580060B - A kind ofly be applicable to the controller of combining inverter and the method for supplying power to of electrical secondary system - Google Patents

Abstract

The invention discloses and be a kind ofly applicable to the controller of combining inverter and the method for supplying power to of electrical secondary system, export through the first alternating current output after line voltage being transformed to alternating current by transformer unit, export capacitor filtering unit storage of electrical energy to and filtering through the first DC output end after being transformed to direct current after rectification unit and capacitor filtering unit, this direct current is also converted to the second direct current through DC conversion power and exports through the second DC output end simultaneously.The present invention has that at least three voltage output ends can obtain 220V alternating voltage respectively, 300V direct voltage, 24V direct voltage provide power supply to secondary device various in combining inverter, has energy-storage function simultaneously and can keep the output that each terminal voltage is stable.

Description

A controller suitable for grid-connected inverters and a power supply method for secondary systems

technical field

The invention belongs to the field of electric energy conversion, and in particular relates to a controller suitable for a grid-connected inverter and a power supply method for a secondary system.

Background technique

As the core equipment of the new energy power generation system, the grid-connected inverter has become the key factor of the whole system in terms of its capacity, performance and cost. In order to meet the requirements of the power system for the low-voltage ride-through performance of the grid-connected inverter, the traditional grid-connected inverter usually uses an uninterruptible power supply (UPS) as the controller of the grid-connected inverter and the power supply of the secondary system. The uninterruptible power supply (UPS) as the controller of the grid-connected inverter and the power supply of the secondary system usually only has one voltage output terminal, and has the following disadvantages:

New energy power stations are usually built in remote areas, such as plateaus, deserts, seas, etc., where the natural environment is relatively harsh, while the built-in batteries of UPS have higher requirements on environmental conditions. , its lifespan is greatly reduced;

The cheap backup UPS has only one output voltage source, low reliability, no voltage stabilization function, and long conversion time, which seriously affects the reliability of the grid-connected inverter. Although the performance of the online UPS is slightly better, the cost is relatively high. High, and there are still reliability issues.

Some UPSs do not have the function of power restart and over-discharge protection. When the power grid is out for a long time, the service life of the internal battery is likely to be reduced due to over-discharge. When the power grid is reconnected, the maintenance personnel of the power station are required to turn on the inverter one by one. The UPS power supply of the device has not only increased the workload, but also has potential safety hazards.

Invention content:

The technical problem to be solved by the present invention is to provide a controller with at least three output voltages, energy storage and stable voltage output functions, which is suitable for a grid-connected inverter controller and a power supply method for a secondary system.

A technical solution invented in order to solve the above technical problems is to provide a controller suitable for grid-connected inverters, including a transformer unit, a rectifier unit, and a capacitor filter unit; the transformer unit is directly taken from the grid port of the grid-connected inverter Electricity, the grid voltage is converted into AC output by the transformer unit, and its output terminal is divided into two circuits, one of which is output through the first AC output terminal, and the other is connected to the rectifier unit, which is connected in series with the capacitor filter unit. The rectifier unit and capacitor The filter unit converts the alternating current into direct current, and the capacitor filter unit stores the capacitance, and the output terminal of the capacitor filter unit is the first direct current output terminal.

Preferably, a DC/DC converter is connected in parallel to the output end of the capacitor filter unit, and the output end of the DC/DC converter is the second direct current output end.

Preferably, the voltage value of the first AC output terminal is 220V; the voltage value of the first DC output terminal is 297V-310V; and the voltage value of the second DC output terminal is 24V.

Preferably, the output end of the capacitor filter unit is also connected in parallel with a DC/AC inverter, the DC/AC inverter converts the direct current obtained by the capacitor filter unit into an alternating current and outputs it through the second alternating current output end, and the DC/AC inverter outputs The alternating current is also converted into direct current by the AC/DC converter and output through the third direct current output terminal.

Preferably, the voltage value of the first AC output terminal and the second AC output terminal is 220V; the voltage value of the first DC output terminal is 297V-310V; the voltage value of the third DC output terminal is 24V.

Preferably, the transformer unit is a single-phase power frequency transformer or a three-phase power frequency transformer; the rectification unit is a single-phase uncontrolled rectifier bridge or a three-phase uncontrolled rectifier bridge.

Preferably, a circuit breaker is provided between the grid port and the transformer unit; the capacitor filter unit includes at least two electrolytic capacitors connected in parallel.

Another technical solution of the present invention is to provide a secondary system power supply method suitable for grid-connected inverters: the transformer unit takes power from the grid port of the grid-connected inverter, and the transformer unit converts the grid voltage into AC power Output through the first alternating current output terminal; the alternating current is converted into high-voltage direct current through the rectification unit and the capacitor filter unit, and then output through the first direct current output terminal, and the electrolytic capacitor in the capacitor filter unit stores electric energy.

Preferably, the direct current output by the capacitor filtering unit is also converted into a low-voltage direct current by the DC/DC converter and output through the second direct current output terminal.

Preferably, the direct current output by the capacitor filter unit is also converted into alternating current by the DC/AC inverter and output through the second alternating current output terminal, and at the same time, the alternating current obtained by the DC/AC inverter is converted into low voltage by the AC/DC converter The direct current is output through the third direct current output terminal.

The technical solution of the present invention has the following benefits: First, the present invention has at least three voltage output terminals when the power grid is normal, which can respectively obtain 220V AC voltage, 300V DC voltage, and 24V DC voltage for various grid-connected inverters. The secondary equipment provides power and stores part of the electrical energy in electrolytic capacitors. Secondly, the filter unit composed of electrolytic capacitors can not only function as a filter, but also enable the entire controller to have an energy storage function. The energy can effectively maintain the power supply of important secondary equipment such as controllers, AC contactors, and relays, and ensure the low-voltage ride-through capability of the grid-connected inverter. When the grid is powered off for a long time, the energy stored in the electrolytic capacitor can be effectively The control system of the grid-connected inverter and the power-off time of the secondary equipment are delayed as much as possible, so that the controller has enough time to automatically run the shutdown process, and the reliability of the grid-connected inverter is guaranteed to the greatest extent. And it can make the at least three voltages outputted by the controller maintain a more stable output.

Description of drawings

Fig. 1 is the system schematic diagram of embodiment 1

Fig. 2 is the system schematic diagram of embodiment 2

Fig. 3 is the system schematic diagram of embodiment 3

In the picture:

1. Power grid port 201, single-phase power frequency transformer 202, three-phase power frequency transformer 301, single-phase uncontrolled rectifier bridge 302, three-phase uncontrolled rectifier bridge 4, capacitor filter unit 401, electrolytic capacitor 501, DC/DC converter 502, AC/DC converter 6, first AC output terminal 701, first DC output terminal 801, second DC output terminal 802, third DC output terminal 9, DC/AC inverter 10, second AC output terminal

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Embodiment 1 shown in Figure 1, a controller suitable for grid-connected inverters disclosed in this embodiment has three voltage output terminals, and the grid port 1 of the grid-connected inverter is sequentially connected to a miniature circuit breaker , single-phase power frequency transformer 201, single-phase uncontrolled rectifier bridge 301, several parallel electrolytic capacitors 401 and DC/DC converter 501; The frequency transformer 201 takes power from the grid port 1 and converts it into 220V alternating current, which is output through the first alternating current output terminal 6, and is used to supply power to electrical equipment such as fans and heaters. At the same time, the 220V AC power obtained by the single-phase power frequency transformer 201 is converted by the single-phase uncontrolled rectifier bridge 301 into 297V-310V DC power and output to the capacitor filter unit 4 composed of parallel electrolytic capacitors 401, and the electrolytic capacitors 401 complete the storage at the same time. able. The capacitor filtering unit 4 provides uninterrupted and relatively stable 297V-310V DC power to electrical equipment such as contactors and relays through the first DC power output terminal 701 . The DC/DC converter 501 converts the 297V to 310V direct current obtained by the electrolytic capacitor 401 into a 24V direct current and supplies power to the control board, touch screen and other electrical equipment through the second direct current output terminal 801, here the first direct current output terminal 701 And the second direct current output terminal 801 is an uninterruptible power supply.

Embodiment 2 shown in Figure 2, the difference between this embodiment and Embodiment 1 is that the single-phase power frequency transformer 201 in Embodiment 1 is replaced with a three-phase power frequency transformer 202, and a three-phase uncontrolled rectifier bridge 302 is used instead The other structures and working processes of the single-phase uncontrolled rectifier bridge 301 in the first embodiment are the same as those in the first embodiment.

Embodiment 3 shown in Figure 3, the difference between this embodiment and Embodiment 2 is that the DC/DC converter 501 in Embodiment 2 is replaced by an AC/DC converter 502, and the AC/DC converter 502 and The DC/AC inverter 9 is connected in series between the capacitor filtering units 4, and its working process is as follows: the transformer unit 2 takes power from the grid port 1 of the grid-connected inverter, and the transformer unit 2 converts the grid voltage into 220V AC power through The first alternating current output terminal 6 outputs; at the same time, the 220V alternating current is transformed into 297V-310V direct current through the rectification unit 3 and the capacitor filter unit 4, and is output through the first direct current output end 701; the direct current is also passed through the DC/AC inverter 9 is converted into 220V alternating current and outputted through the second alternating current output terminal 10 to supply power to electrical equipment such as AC contactors and relays. At the same time, the 220V AC power obtained by the DC/AC inverter 9 is converted into 24V DC power by the AC/DC converter 502 and then output through the third DC output terminal 802 to supply power to electrical equipment such as control boards and contactors.

The present invention can respectively obtain 220V AC voltage, 300V DC voltage, and 24V DC voltage to provide power for various secondary devices in the grid-connected inverter when the power grid is normal, and store part of the electric energy in the electrolytic capacitor 401 at the same time. When the grid voltage drops suddenly due to instantaneous short circuit, large motor startup, etc., the energy stored in the electrolytic capacitor 401 can effectively maintain the power supply of important secondary equipment such as controllers, AC contactors, relays, etc., as an uninterrupted The power supply is used to ensure the low voltage ride-through capability of the grid-connected inverter. In addition, when the power grid is out of power for a long time, the energy stored in the electrolytic capacitor 401 can effectively delay the power outage time of the control system of the grid-connected inverter and the secondary equipment, so that the controller has enough time to automatically run the shutdown process, The reliability of the grid-connected inverter is guaranteed to the greatest extent.

It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should belong to the protection scope of the appended claims of the present invention.

Claims (6)

1. be applicable to a controller for combining inverter, it is characterized in that: comprise transformer unit, rectification unit, capacitor filtering unit (4);

Transformer unit is by electrical network port (1) the directly power taking of combining inverter, by transformer unit, line voltage is converted to alternating current to export, its output is divided into two-way, and a road first alternating current output (6) exports, another road connects rectification unit

Rectification unit is serial capacitance filter unit (4) again, by rectification unit and capacitor filtering unit (4), alternating current is converted to direct current, by capacitor filtering unit (4) storage of electrical energy, the output of capacitor filtering unit (4) is the first DC output end (701); The output of capacitor filtering unit (4) is also parallel with DC/DC converter (501), and the output of described DC/DC converter (501) is the second DC output end (801); The magnitude of voltage of described first alternating current output (6) is 220V; The magnitude of voltage of described first DC output end (701) is 297V ~ 310V; The magnitude of voltage of described second DC output end (801) is 24V.

2. a kind of controller being applicable to combining inverter according to claim 1, it is characterized in that: capacitor filtering unit (4) output is also parallel with DC/AC inverter (9), the direct current obtained by capacitor filtering unit (4) is converted to alternating current and exports through the second alternating current output (10) by described DC/AC inverter (9), and the alternating current that described DC/AC inverter (9) exports also is converted to direct current through AC/DC converter (502) and exports through the 3rd DC output end (802).

3. a kind of controller being applicable to combining inverter according to claim 2, is characterized in that: the magnitude of voltage of described first alternating current output (6) and the second alternating current output (10) is 220V; The magnitude of voltage of described first DC output end (701) is 297V ~ 310V; The magnitude of voltage of described 3rd DC output end (802) is 24V.

4. a kind of controller being applicable to combining inverter according to claims 1 to 3 any one, is characterized in that: described transformer unit is single phase industrial frequence transformer (201) or three-phase main-frequency transformer (202); Described rectification unit is single-phase uncontrollable rectifier bridge (301) or three-phase uncontrollable rectifier bridge (302).

5. a kind of controller being applicable to combining inverter according to claims 1 to 3 any one, is characterized in that: between described electrical network port (1) and described transformer unit, be provided with circuit breaker; Described capacitor filtering unit (4) comprises at least two electrochemical capacitors (401) in parallel.

6. one kind is applicable to the electrical secondary system method of supplying power to of combining inverter, it is characterized in that: transformer unit, from electrical network port (1) power taking of combining inverter, exports through the first alternating current output (6) after line voltage being transformed to alternating current by transformer unit; Described alternating current exports through the first DC output end (701) be transformed to direct current after rectification unit and capacitor filtering unit (4) after, electrochemical capacitor (401) storage of electrical energy in capacitor filtering unit (4); The direct current that capacitor filtering unit (4) exports also is converted to low-voltage DC through DC/DC converter (501) and exports through the second DC output end (801); The direct current that capacitor filtering unit (4) exports also is converted to alternating current through DC/AC inverter (9) and exports through the second alternating current output (10), meanwhile, the alternating current obtained by DC/AC inverter (9) is converted to after low-voltage DC through AC/DC converter (502) and is exported by the 3rd DC output end (802).