CN204906217U - Gto photovoltaic inverter - Google Patents

Abstract

The utility model discloses a GTO photovoltaic inverter, including direct current breaker, steady voltage electric capacity, three -phase contravariant bridge, wave filter, GTO and pressure reduction means. Direct current breaker includes the third switch, and pressure reduction means includes precharge resistance and non -linear resistor, and the one end of precharge resistance is connected in the positive pole of steady voltage electric capacity through first wire, and the other end of precharge resistance is connected with the privates through first wire, and non -linear resistor's one end is passed through the second wire and is connected with the positive pole of steady voltage electric capacity, non -linear resistor's other end ground connection. Still be equipped with the fourth switch on the privates, be equipped with the second switch and be equipped with the second switch on first wire on the second wire. The utility model discloses a GTO photovoltaic inverter can improve photovoltaic inverter the capacity of being incorporated into the power networks, reduce the pick -up current, to the impact of electric wire netting when reducing photovoltaic inverter and starting.

Description

GTO photovoltaic DC-to-AC converter

Technical field

The utility model relates to field of solar thermal power generation, is specifically related to a kind of GTO photovoltaic DC-to-AC converter.

Background technology

Solar energy has the advantages such as safe, clean and resource generality, can become the regenerative resource that alternative fossil energy is main.Solar energy power generating in its developmental research, market development and industrialized manufacture technology already as the focus of world community keen competition.

Fig. 1 is the photovoltaic DC-to-AC converter of prior art.As shown in Figure 1, current photovoltaic DC-to-AC converter adopts three phase inverter bridge.In order to limit photovoltaic DC-to-AC converter first time start the impulse current produced time, first closed fuse F1, is charged to electric capacity of voltage regulation by pre-charge resistance R, after capacitor charging completes, finally closed DC circuit breaker.

But such photovoltaic DC-to-AC converter but has following defect.

First, when AC circuit breaker to utilize in coil by electric current, produce magnetic flux in electromagnet, iron core, owing to being subject to the effect of electric field force, realizing main circuit and closes a floodgate and separating brake.Due to larger impulse current can be produced during inverter startup, larger voltage flicker is produced to the voltage on line side of power supply, simultaneously comparatively large owing to starting stress, electric equipment is produced and impacts, the useful life of inverter is reduced.Large-scale ground photovoltaic plant requires that electric equipment reaches 25 years useful life.AC circuit breaker start and stop every day, between total life cycle, circuit breaker break-make number of times is more than 18000 times.In addition, easily there is the mechanical breakdown such as loosened screw, contact abrasion in AC circuit breaker, and then cause inverter to stop transport in long-term high-frequency use procedure, affects photovoltaic power station power generation amount.

Secondly, in order to limit photovoltaic DC-to-AC converter first time start the impulse current produced time, first closed fuse F1, is charged to electric capacity of voltage regulation by pre-charge resistance R, after capacitor charging completes, finally closed DC circuit breaker.But, during due to pre-charge process, electric capacity of voltage regulation maximum withstand voltage be the open circuit voltage of photovoltaic array, that is withstand voltage open circuit voltage that must be greater than photovoltaic array of the power device of photovoltaic DC-to-AC converter.Therefore, we are when designing the group string of photovoltaic array, and the open circuit voltage of the photovoltaic module of going here and there should not be greater than the withstand voltage of power device of inverter.Therefore, along with the large-scale development of photovoltaic industry, the grid-connected photovoltaic inverter of existing low capacity has become restriction photovoltaic plant to bottleneck that is intelligent, modularization development.

Utility model content

The purpose of this utility model is to provide a kind of GTO photovoltaic DC-to-AC converter, to improve the grid connection capacity of photovoltaic DC-to-AC converter and to solve photovoltaic DC-to-AC converter starting current greatly, to the problem that electric equipment impacts obviously and failure rate is high.

For achieving the above object, the utility model provides a kind of GTO photovoltaic DC-to-AC converter, described GTO photovoltaic DC-to-AC converter comprises DC circuit breaker, electric capacity of voltage regulation, three phase inverter bridge, filter, GTO and dropping equipment, and wherein, described DC circuit breaker comprises the 3rd switch (S ₁), described 3rd switch (S ₁) be arranged at privates (L ₀) on, described dropping equipment comprises pre-charge resistance (R ₁) and nonlinear resistance (R ₂), described pre-charge resistance (R ₁) one end by the first wire (L ₁) be connected to the positive pole of described electric capacity of voltage regulation, described pre-charge resistance (R ₁) the other end by the first wire (L ₁) and described privates (L ₀) connect, described nonlinear resistance (R ₂) one end by the second wire (L ₂) be connected with the positive pole of described electric capacity of voltage regulation, described nonlinear resistance (R ₂) other end ground connection, and at described privates (L ₀) on be also provided with the 4th switch (QB), at described first wire (L ₁) be provided with second switch (QB ₁) and at described second wire (L ₂) be provided with second switch (QB ₂).

Preferably, described pre-charge resistance is adjustable resistance.

Preferably, described dropping equipment also comprises the first relay, and described first relay is for controlling described first switch (QB ₁) opening and closing.

Preferably, described dropping equipment also comprises power supply, and described power supply is electrically connected with described first relay thus provides electric energy for described first relay.

Preferably, described dropping equipment also comprises the first CPU module, and described first CPU module is electrically connected with described first relay thus sends instruction to described first relay.

Preferably, the input of described GTO is electrically connected with the output of described filter; And described GTO is arranged through the angle of flow controlling described GTO, the output voltage of described GTO photovoltaic DC-to-AC converter is increased gradually from null value, until the whole conducting of described GTO, the output voltage of described GTO photovoltaic DC-to-AC converter reaches maximum.

Preferably, described GTO photovoltaic DC-to-AC converter also comprises interchange main contactor, described interchange main contactor is arranged to when after the whole conducting of described GTO, and described interchange main contactor closes, and described GTO is arranged to described GTO disconnection after described interchange main contactor is closed.

Preferably, described interchange main contactor is in parallel with described GTO.

Preferably, described GTO photovoltaic DC-to-AC converter also comprises control system, described control system comprises soft-start module and the second CPU module, described soft-start module and described second CPU module electrical connection, and described soft-start module comprises multiple second relay, described multiple second relay is arranged to receive instruction from described second CPU module and control described GTO and the described conducting and the disconnection that exchange main contactor according to this instruction.

Preferably, described multiple second relay comprises a class relay, two class relays and three class relays, and described set-up of control system becomes:

When the alternating voltage of the input of described GTO and the output of described GTO are by same frequently for the line voltage accessed, same to phase time, described second CPU module sends instruction to a described class relay, GTO described in a described class Control opens, the output voltage of described GTO increases gradually, until the whole conducting of described GTO; And

When described GTO photovoltaic DC-to-AC converter is after rated voltage is run, described second CPU module sends instruction to respectively described two class relays and described three class relays, GTO described in described two class Controls is disconnected, exchange main contactor described in described three class Controls to close, thus complete the start-up course of described GTO photovoltaic DC-to-AC converter.

By GTO photovoltaic DC-to-AC converter of the present utility model, the grid connection capacity of photovoltaic DC-to-AC converter can be improved, starting current can also be reduced, reduce the impact to electrical network when photovoltaic DC-to-AC converter starts, improve integration of equipments degree, saving equipment capital, ensures stability and the reliability of system works, thus improves power supply quality and service life of equipment.Simultaneously compared with conventional photovoltaic inverter, save circuit breaker, with box-type substation with the use of, meet the selectivity characteristic of protection, save taking up room of equipment, achieve the integrated development of equipment.

Accompanying drawing explanation

Fig. 1 is the topology diagram of the photovoltaic DC-to-AC converter of prior art.

Fig. 2 is the topology diagram of GTO photovoltaic DC-to-AC converter of the present utility model.

Fig. 3 is that the second CPU module of GTO photovoltaic DC-to-AC converter of the present utility model controls schematic diagram.

Fig. 4 is that the soft-start module of GTO photovoltaic DC-to-AC converter of the present utility model controls schematic diagram.

Fig. 5 is phase voltage figure corresponding in the GTO regulating circuit of GTO photovoltaic DC-to-AC converter of the present utility model.

Embodiment

Below with reference to accompanying drawing, preferred embodiment of the present utility model is described in detail, understands the purpose of this utility model, feature and advantage so that clearer.It should be understood that embodiment shown in the drawings is not the restriction to the utility model scope, and the connotation just in order to technical solutions of the utility model are described.

Term explanation

Photovoltaic DC-to-AC converter: by power electronic device contact resistance electric capacity, with the break-make of the mode control device of pulse width modulation, the direct current that header box transmission comes is transformed into alternating current, completes the MPPT maximum power point tracking of photovoltaic module simultaneously, ensure Based Intelligent Control and anti-islanding effect etc.

Pre-charge resistance: inverter DC bus capacitance before charging both end voltage be zero, be equivalent to short circuit in the moment of equipment charge, very large impulse current can be produced, be easy to cause the power device of inverter to damage.Therefore need to connect a resistance at charge circuit in pre-charge process, to play the effect of Limited Current.This resistance is just called pre-charge resistance.

Electric capacity of voltage regulation: a voltage source positive and negative terminal electric capacity in parallel, during for the circuit such as copped wave, inversion, has good filter action; When change in voltage, due to the effect of capacitance energy storage, the voltage at two ends can not suddenly change, and ensure that the steady of voltage.

GTO: gate level turn-off thyristor is the element be made up of PNPN four-level semiconductor, and have anode A, negative electrode K and controlled stage G tri-electrodes, it can realize the system without deaerator of alternating current in circuit.

GTO photovoltaic DC-to-AC converter: the photovoltaic DC-to-AC converter containing GTO (GTO).

GTO photovoltaic DC-to-AC converter of the present utility model generally includes DC circuit breaker, electric capacity of voltage regulation, three phase inverter bridge, filter, gate level turn-off thyristor (hereinafter referred to as GTO) and dropping equipment, wherein, this DC circuit breaker comprises the 3rd switch (S ₁), the 3rd switch (S ₁) be arranged at privates (L ₀) on, this dropping equipment comprises pre-charge resistance (R ₁) and nonlinear resistance (R ₂), this pre-charge resistance (R ₁) one end by the first wire (L ₁) be connected to the positive pole of this electric capacity of voltage regulation, this pre-charge resistance (R ₁) the other end by the first wire (L ₁) and this privates (L ₀) connect, this nonlinear resistance (R ₂) one end by the second wire (L ₂) be connected with the positive pole of this electric capacity of voltage regulation, this nonlinear resistance (R ₂) other end ground connection, and at this privates (L ₀) on be also provided with the 4th switch (QB), at this first wire (L ₁) be provided with second switch (QB ₁) and at this second wire (L ₂) be provided with second switch (QB ₂).

Below in conjunction with Fig. 1, one embodiment of GTO photovoltaic DC-to-AC converter of the present utility model is described in detail.

Fig. 1 is the topology diagram of GTO photovoltaic DC-to-AC converter 100 of the present utility model.As shown in Figure 1, GTO photovoltaic DC-to-AC converter 100 comprises DC circuit breaker 10, electric capacity of voltage regulation 20, three phase inverter bridge 30, filter 40, dropping equipment 50, GTO60 and exchanges main contactor 70.Wherein, DC circuit breaker 10, electric capacity of voltage regulation 20, three phase inverter bridge 30, filter 40 are electrically connected via wire successively, the output of filter 40 is electrically connected with the input of the input and GTO60 that exchange main contactor 70, exchange main contactor 70 and GTO60 parallel connection, DC circuit breaker 10 is for connecting photovoltaic module, and AC circuit breaker is for connecting electrical network.

Dropping equipment 50 comprises the first CPU module 51, relay 52, power supply 53, pre-charge resistance R ₁, nonlinear resistance R ₂, the first wire L ₁, the second wire L ₂, the first switch QB ₁, second switch QB ₂and the 4th switch QB.

DC circuit breaker 10 comprises multiple switch, wherein the 3rd switch S ₁be arranged at privates L ₀on, pre-charge resistance R ₁one end by the first wire L ₁be connected to the positive pole of electric capacity of voltage regulation 20, pre-charge resistance R ₁the other end by the first wire L ₁be connected to privates L ₀on, nonlinear resistance R ₂one end by the second wire L ₂be connected with the positive pole of electric capacity of voltage regulation 20, nonlinear resistance R ₂other end ground connection, at privates L ₀on be also provided with the 4th switch QB, at the first wire L ₁be provided with the first switch QB ₁with at the second wire L ₂be provided with second switch QB ₂.Wherein, privates L is passed through again after the first parallel connection of multiple switches of DC circuit breaker 10 ₀connect with electric capacity of voltage regulation 20, the 4th switch QB is for controlling the break-make of DC circuit breaker 10 and electric capacity of voltage regulation 20.

Preferably, pre-charge resistance R ₁for adjustable resistance.

Power supply 53 is electrically connected with the first relay 52 thus provides electric energy for the first relay 52, first CPU module 51 is electrically connected with the first relay 52 thus sends instruction to the first relay 52, and the first relay 52 controls the first switch QB under the instruction of the first CPU module 51 ₁opening and closing.

When needing to open GTO photovoltaic DC-to-AC converter, undertaken by following process:

(1) closed second switch QB ₂with the 3rd switch S ₁, node 1., 2. between voltage be reduced to voltage U by open circuit voltage ₁, wherein, voltage U ₁value can be real-time calculated value, also can be preset value, but can not lower than the minimum normal operating voltage of system;

(2) closed first switch QB ₁, by pre-charge resistance R ₁precharge is carried out to electric capacity of voltage regulation 20, wherein, signal can be sent by CPU module and make the first relay 52 action, thus allow the first relay 52 control switch QB ₁closed;

(3) after precharge completes, all switches of closed DC circuit breaker 10;

(4) closed 4th switch QB;

(5) after GTO photovoltaic DC-to-AC converter parallel-adder settle-out time t, second switch QB is disconnected ₂, thus complete the machine of opening.

Below by the GTO photovoltaic DC-to-AC converter comparatively bright of the present utility model with conventional photovoltaic inverter to the improvement of grid connection capacity.

The input of photovoltaic DC-to-AC converter, output performance parameter respectively in table 1 and table 2, access the parameter of photovoltaic module in table 3.

Table 1 photovoltaic DC-to-AC converter input parameter

Maximum DC input power (kW)	MPPT voltage range (VDC)	Maximum input direct-current electric current (A)
			825	450～820	1600

Table 2 photovoltaic DC-to-AC converter output parameter

Rated output power (kW)	Peak power output (kW)	Rated operational voltage (V)	Specified output frequency (Hz)
				750	810	315	50

The performance parameter of table 3 photovoltaic module

Rated power (kW)	Open circuit voltage (V)	Operating voltage (V)
			310	45.45	37.00

If adopt traditional photovoltaic DC-to-AC converter serial connection photovoltaic module, so photovoltaic module be often connected in series into block number N _maxfollowing formula should be met:

45.45N _max≤820(1)

The solution of formula (1) is;

N _max＝18(2)

If adopt photovoltaic DC-to-AC converter of the present utility model be connected in series photovoltaic module, be reduced to operating voltage 37.00V by open circuit voltage 45.45V, so photovoltaic module be often connected in series into block number N _maxformula (3) should be met

37.00N _max≤820(3)

The solution of formula (3) is:

N _max＝22(4)

So the rated power of photovoltaic DC-to-AC converter can rise to

$P=750*\frac{22}{18}=916.6kW---\left(5\right)$

As can be seen from formula (5), photovoltaic inverter grid-connected capacity of the present utility model obviously improves.Compared to traditional photovoltaic DC-to-AC converter, grid connection capacity improves 22.2%.

In another embodiment, GTO photovoltaic DC-to-AC converter of the present utility model also comprises control system, and control system comprises the second CPU module 81 and soft-start module 82, and soft-start module 82 is connected by terminal with the second CPU module 81.Terminal is the corresponding soft start state of control system realization or the function of action respectively, and table 1 is terminal function table.

Table 1

Terminal	Function
		001	GTO on/off switch state
002	GTO closes a floodgate
		003	GTO separating brake
004	Main contactor on/off switch state
		005	Main contactor closes a floodgate
006	Main contactor separating brake
		007	Main contactor is reported to the police

Fig. 3 is that the second CPU module 81 controls schematic diagram, Fig. 4 is the control schematic diagram of soft-start module 82, as shown in figs. 34, soft-start module 82 comprises class relay J 1, two class relay J 2, three class relay J 3, four class relay J 4 and many loops A1, A2, A3, B1, B2, B3, B4, and the divide-shut brake action exchanging main contactor 70 and GTO60 has come by controlling each relay.

When soft start photovoltaic DC-to-AC converter 100 starts, control system detects from filter 40 alternating voltage out and the whether same frequency of line voltage, the homophase that will be incorporated to by GTO60, when detecting that filter 40 alternating voltage out and the line voltage that will be incorporated to by GTO60 are with frequency, same to phase time, second CPU module sends instruction 002 to a class relay J 1, one class relay J 1 receives action after instruction, control switch is closed, the loop conducting of A1 place, GTO60 starts, the output voltage of GTO60 increases gradually, until the full conducting of GTO60.After GTO photovoltaic DC-to-AC converter 100 is operated in rated voltage, second CPU module sends instruction 003 to two class relay J 2, send instruction 005 to three class relay J 3, thus two class relay J 2 control GTO60 disconnect, three class relay J 3 control to exchange main contactor 70 and close, and complete the start-up course of GTO photovoltaic DC-to-AC converter 100.

Fig. 5 is phase voltage figure corresponding in the regulating circuit of GTO60.Below for certain phase voltage, analyze the output voltage characteristic of GTO photovoltaic DC-to-AC converter 100.As shown in Figure 5, wherein U is the input voltage of GTO60, and α is Trigger Angle, for afterflow angle, θ is the angle of flow.

As seen from Figure 5, conduction angle, Trigger Angle α and afterflow angle between functional relation be:

If the expression formula of voltage U is:

U＝U _msinωt(2)

Now GTO60 output voltage effective value U _lexpression formula is

Formula (3) abbreviation is

From formula (4), when afterflow angle when being constant, as long as the size changing GTO Trigger Angle α just can change the output voltage of GTO, the requirement that the output voltage realizing inverter changes according to predetermined rule.

Therefore, by the angle of flow of control GTO the output voltage of GTO photovoltaic DC-to-AC converter just can be made to increase gradually from null value, until the whole conducting of described GTO, the output voltage of GTO photovoltaic DC-to-AC converter reaches maximum.

By GTO photovoltaic module 100 of the present utility model, the capacity of photovoltaic DC-to-AC converter can be improved, starting current can also be reduced, reduce the impact to electrical network when photovoltaic DC-to-AC converter starts, improve integration of equipments degree, saving equipment capital, ensures stability and the reliability of system works, thus improves power supply quality and service life of equipment.Compared with conventional photovoltaic inverter, save circuit breaker, with box-type substation with the use of, meet protection selectivity characteristic, save taking up room of equipment, achieve the integrated development of equipment.

Below described preferred embodiment of the present utility model in detail, but it will be appreciated that, after having read above-mentioned instruction content of the present utility model, those skilled in the art can make various changes or modifications the utility model.These equivalent form of values fall within the application's appended claims limited range equally.

Claims (6)

1. a GTO photovoltaic DC-to-AC converter, is characterized in that, described GTO photovoltaic DC-to-AC converter comprises DC circuit breaker, electric capacity of voltage regulation, three phase inverter bridge, filter, GTO and dropping equipment, and wherein, described DC circuit breaker comprises the 3rd switch (S ₁), described 3rd switch (S ₁) be arranged at privates (L ₀) on, described dropping equipment comprises pre-charge resistance (R ₁) and nonlinear resistance (R ₂), described pre-charge resistance (R ₁) one end by the first wire (L ₁) be connected to the positive pole of described electric capacity of voltage regulation, described pre-charge resistance (R ₁) the other end by the first wire (L ₁) and described privates (L ₀) connect, described nonlinear resistance (R ₂) one end by the second wire (L ₂) be connected with the positive pole of described electric capacity of voltage regulation, described nonlinear resistance (R ₂) other end ground connection, and at described privates (L ₀) on be also provided with the 4th switch (QB), at described first wire (L ₁) be provided with second switch (QB ₁) and at described second wire (L ₂) be provided with second switch (QB ₂).

2. GTO photovoltaic DC-to-AC converter according to claim 1, is characterized in that, the input of described GTO is electrically connected with the output of described filter; And described GTO is arranged through the angle of flow controlling described GTO, the output voltage of described GTO photovoltaic DC-to-AC converter is increased gradually from null value, until the whole conducting of described GTO, the output voltage of described GTO photovoltaic DC-to-AC converter reaches maximum.

3. GTO photovoltaic DC-to-AC converter according to claim 2, it is characterized in that, described GTO photovoltaic DC-to-AC converter also comprises interchange main contactor, described interchange main contactor is arranged to when after the whole conducting of described GTO, described interchange main contactor closes, and described GTO is arranged to described GTO disconnection after described interchange main contactor is closed.

4. GTO photovoltaic DC-to-AC converter according to claim 3, is characterized in that, described interchange main contactor is in parallel with described GTO.

5. GTO photovoltaic DC-to-AC converter according to claim 3, it is characterized in that, described GTO photovoltaic DC-to-AC converter also comprises control system, described control system comprises soft-start module and the second CPU module, described soft-start module and described second CPU module electrical connection, and described soft-start module comprises multiple second relay, described multiple second relay is arranged to receive instruction from described second CPU module and control described GTO and the described conducting and the disconnection that exchange main contactor according to this instruction.

6. GTO photovoltaic DC-to-AC converter according to claim 5, is characterized in that, described multiple second relay comprises a class relay, two class relays and three class relays, and described set-up of control system becomes:

When the alternating voltage of the input of described GTO and the output of described GTO are by same frequently for the line voltage accessed, same to phase time, described second CPU module sends instruction to a described class relay, GTO described in a described class Control opens, the output voltage of described GTO increases gradually, until the whole conducting of described GTO; And

When described GTO photovoltaic DC-to-AC converter is after rated voltage is run, described second CPU module sends instruction to respectively described two class relays and described three class relays, GTO described in described two class Controls is disconnected, exchange main contactor described in described three class Controls to close, thus complete the start-up course of described GTO photovoltaic DC-to-AC converter.