CN105071645A

CN105071645A - High-power photovoltaic grid-connected inverter

Info

Publication number: CN105071645A
Application number: CN201510476490.7A
Authority: CN
Inventors: 侯克淅; 慕小斌; 马勇
Original assignee: Henan Senyuan Electric Co Ltd
Current assignee: Henan Senyuan Electric Co Ltd
Priority date: 2015-08-06
Filing date: 2015-08-06
Publication date: 2015-11-18

Abstract

The invention relates to a high-power photovoltaic grid-connected inverter. In the structure, the high-power photovoltaic grid-connected inverter comprises two groups A and B of current converters and matched reactors and capacitors, wherein the group A of current converters and the group B of current converters are connected in parallel to run and are three-phase two-level current converters with power of 500kW, 50kW, over 500kW or over 50kW; the power-frequency and high-frequency three-phase filter reactors have induction values of 0.08mH and 0.3mH; the three-phase current converter with power of 500kW or over 500kW is used for converting direct current electric energy of a photovoltaic cell panel into alternating current electric energy connected into the power grid in parallel at a switching frequency of 1,500Hz according to a control principle of space vector pulse width modulation(SVPWM); and the three-phase two-level current converter with power of 50kW or over 50kW is connected to a power grid access end in parallel. The high-power photovoltaic grid-connected inverter has the advantages that the switching frequency and the active loss of a power electronic device in a high-power current converter are low, and the switching frequency and the harmonic compensation ability of the power electronic device in a low-power current converter are high, and harmonic containing rates of grid-connected currents of the inverter at a full power range are all lower than 2%.

Description

A kind of high-power photovoltaic synchronization inverter

Technical field

What the present invention relates to is a kind of high-power photovoltaic synchronization inverter, particularly to the compensation of 500kW and above power photovoltaic grid connection inverter output current harmonic wave.

Technical background

Photovoltaic combining inverter is the power electronic equipment that a kind of direct current energy for being produced by solar panel is converted to AC energy.Its core is by controlling opening or turn off and export the sine wave of the standard of expectation after the filtering of reactor and capacitor of power electronic power device (as IGBT etc.), but because the switching frequency of power electronic device is limited, the factors such as the higher and departure of the cost of reactor cause reality with in the switching frequency of power electronic device can not more than 20kHz in high-power photovoltaic synchronization inverter, the rated capacity of reactor can not exceed 14% of inverter total capacity, departure is greater than 0.5%, the current harmonics containing ratio exported when these factors cause the power output of inverter to be operated in 30% and above power section is above more satisfactory, but the current harmonics containing ratio that power output exports at 30% and following power Duan Shiqi obviously increases, in some engineerings, its output current harmonics containing ratio is even more than 10%, this is totally unfavorable to whole network system.

Summary of the invention

What the present invention proposed is a kind of high-power photovoltaic synchronization inverter, and its object is intended to ensure current harmonics containing ratio that inverter is connected to the grid in total power section all lower than 2%, and the power proportions of two groups of current transformers is 10:1.

Technical scheme of the present invention, a kind of high-power photovoltaic synchronization inverter, its structure is made up of A, B two groups of current transformers and supporting reactor thereof and capacitor, A, B two groups of current transformer parallel operation, wherein, A group current transformer is with three-phase two level current transformer of 500kW or more power, B group current transformer is with three-phase two level current transformer of 50kW or more power, A group inductance value is the power frequency three-phase filter reactor of 0.08mH, B group inductance value is the high frequency three-phase filter reactor of 0.3mH, the direct current energy of photovoltaic battery panel is converted to AC energy with the switching frequency of 1500Hz according to the Controlling principle of SVPWM and is connected to the grid by the 3-phase power converter of 500kW or more power, three-phase two level current transformer of 50kW or more power is connected in parallel on electrical network incoming end, for compensating ripple current and the harmonic wave of inverter output, ensure current harmonics containing ratio that inverter is connected to the grid in total power section all lower than 2%, the power proportions of two groups of current transformers is 10:1.

Advantage of the present invention:

1) two level current transformers be made up of IGBT switch transistor T 1-T6 are to export to the filter reactor of the 0.08mH be made up of inductor L1-L3 and the alternating current formed after filter C1-C3 filtering containing harmonic wave after the conversion of the switching frequency of 1500Hz; The active power filtering link be made up of IGBT switching tube S1-S6, inductor L4-L6 and filter C4-C6, the switching frequency reducing IGBT switch transistor T 1-T6 makes its active loss reduce, the inductance value reducing inductor L1-L3 makes its cost reduce, increase active power filtering link simultaneously and solve the harmonic wave increase being reduced by the reduction of IGBT switch transistor T 1-T6 switching frequency, inductor L1-L3 inductance value and caused, the power proportions of two groups of current transformers is 10:1;

2) in high-power converter, power electronic device switching frequency is low, active loss is little, in small-power current transformer, power electronic device switching frequency is high, compensation harmonic ability strong, and its advantage is that the relative harmonic content of inverter in total power section grid-connected current is all lower than 2%.

Accompanying drawing explanation

Accompanying drawing 1 is the topology theory figure of high-power photovoltaic synchronization inverter.

Embodiment

A kind of high-power photovoltaic synchronization inverter, its structure is made up of A, B two groups of current transformers and supporting reactor thereof and capacitor, A, B two groups of current transformer parallel operation, and wherein, A group current transformer is with three-phase two level current transformer of 500kW or more power, B group current transformer is with three-phase two level current transformer of 50kW or more power, A group inductance value is the power frequency three-phase filter reactor of 0.08mH, B group inductance value is the high frequency three-phase filter reactor of 0.3mH, the direct current energy of photovoltaic battery panel is converted to AC energy with the switching frequency of 1500Hz according to the Controlling principle of SVPWM and is connected to the grid by the 3-phase power converter of 500kW or more power, three-phase two level current transformer of 50kW or more power is connected in parallel on electrical network incoming end, for compensating ripple current and the harmonic wave of inverter output, ensure current harmonics containing ratio that inverter is connected to the grid in total power section all lower than 2%, the power proportions of two groups of current transformers is 10:1.

The input of described A group current transformer connect solar panel conflux after output, power electronic device in current transformer is with the mutual switching state of the switching frequency of 1500Hz control strategy desirably, the electric current that current transformer exports exports as the inverter current containing harmonic wave after inductance value is the three-phase reactor of 0.08mH and AC capacitor filtering

Described B group current transformer is connected in parallel on the port of export of inverter current, by detecting the harmonic components of inverter current and exporting the harmonic current contrary with its equal and opposite in direction direction thus compensate the harmonic wave that inverter current contains, the harmonic current content that inverter complete machine is exported in whole power section all lower than 2%.

Technical scheme of the present invention is further described below in conjunction with accompanying drawing:

As shown in Figure 1, a kind of high-power photovoltaic synchronization inverter, its structure is made up of A, B two groups of current transformers and supporting reactor thereof and capacitor, A, B two groups of current transformer parallel operation, wherein, A group current transformer is with three-phase two level current transformer of 500kW or more power; B group current transformer is with three-phase two level current transformer of 50kW or more power, A group inductance value is the power frequency three-phase filter reactor of 0.08mH, B group inductance value is the high frequency three-phase filter reactor of 0.3mH, the direct current energy of photovoltaic battery panel is converted to AC energy with the switching frequency of 1500Hz according to the Controlling principle of SVPWM and is connected to the grid by the 3-phase power converter of 500kW or more power, and three-phase two level current transformer of 50kW or more power is connected in parallel on electrical network incoming end;

Described A group current transformer, its structure is by A capacitor C ₄, six IGBT switch transistor T 1-T6 A two level current transformer, the A filter reactor be made up of inductor L1-L3 and the A filter be made up of electric capacity C1-C3 that form; Wherein A capacitor C ₄in parallel with A two level current transformer, the IGBT switch transistor T 1 in A two level current transformer and the contact of the 6th IGBT switch transistor T 6 are connected the first electric capacity C1 in first inductor L1, A filter in A filter reactor successively; The 3rd IGBT switch transistor T 3 in A two level current transformer and the contact of the 4th IGBT switch transistor T 4 are connected the second electric capacity C2 in second inductor L2, A filter in A filter reactor successively; The 5th IGBT switch transistor T 5 in A two level current transformer and the contact of the 2nd IGBT switch transistor T 2 are connected the 3rd electric capacity C3 in the 3rd inductor L3, A filter in A filter reactor successively;

Described B group current transformer, its structure is by B capacitor C' ₄, six IGBT switch transistor T ' 1-T'6 B two level current transformer, the B filter reactor be made up of inductor L'1-L'3 and the B filter be made up of electric capacity C'1-C'3 that form; Wherein B capacitor C' ₄in parallel with B two level current transformer, IGBT switch transistor T ' 1 in B two level current transformer and the contact of the 6th IGBT switch transistor T ' 6 are connected the first electric capacity C'1 in first inductor L'1, B filter in B filter reactor successively; The 3rd IGBT switch transistor T ' 3 in B two level current transformer and the contact of the 4th IGBT switch transistor T ' 4 are connected the second electric capacity C'2 in second inductor L'2, B filter in B filter reactor successively; The 5th IGBT switch transistor T ' 5 in B two level current transformer and the contact of the 2nd IGBT switch transistor T ' 2 are connected the 3rd electric capacity C'3 in the 3rd inductor L'3, B filter in B filter reactor successively; The electric current flowing through B inductor L'1-L'3 and the electric current flowing through A inductor L1-L3 intersect.

Claims

1. a high-power photovoltaic synchronization inverter, it is characterized in that being made up of A, B two groups of current transformers and supporting reactor thereof and capacitor, A, B two groups of current transformer parallel operation, wherein, A group current transformer is with three-phase two level current transformer of 500kW or more power; B group current transformer is with three-phase two level current transformer of 50kW or more power, A group inductance value is the power frequency three-phase filter reactor of 0.08mH, B group inductance value is the high frequency three-phase filter reactor of 0.3mH, the direct current energy of photovoltaic battery panel is converted to AC energy with the switching frequency of 1500Hz according to the Controlling principle of SVPWM and is connected to the grid by the 3-phase power converter of 500kW or more power, and three-phase two level current transformer of 50kW or more power is connected in parallel on electrical network incoming end.

2. a kind of high-power photovoltaic synchronization inverter according to claim 1, it is characterized in that described A group current transformer, its structure is A two level current transformer, the A filter reactor be made up of inductor L1-L3 and the A filter be made up of three electric capacity (C1-C3) that are made up of A capacitor, six IGBT switching tubes (T1-T6); Wherein A capacitor is in parallel with A two level current transformer, and the IGBT switching tube (T1) in A two level current transformer is connected the first inductor (L1) in A filter reactor, the first electric capacity (C1) in A filter successively with the contact of the 6th IGBT switching tube (T6); The 3rd IGBT switching tube (T3) in A two level current transformer is connected the second inductor (L2) in A filter reactor, the second electric capacity (C2) in A filter successively with the contact of the 4th IGBT switching tube (T4); The 5th IGBT switching tube (T5) in A two level current transformer and the contact of the 2nd IGBT switching tube (T2) are connected the 3rd inductor (L3) in A filter reactor, the 3rd electric capacity (C3) in A filter successively.

3. a kind of high-power photovoltaic synchronization inverter according to claim 1, it is characterized in that described B group current transformer, its structure is B two level current transformer, the B filter reactor be made up of three inductors (L'1-L'3) and the B filter be made up of three electric capacity (C'1-C'3) that are made up of B capacitor (C'4), six IGBT switching tubes (T'1-T'6); Wherein B capacitor (C' ₄) in parallel with B two level current transformer, the IGBT switching tube (T'1) in B two level current transformer is connected the first inductor (L'1) in B filter reactor, the first electric capacity (C'1) in B filter successively with the contact of the 6th IGBT switching tube (T'6); The 3rd IGBT switching tube (T'3) in B two level current transformer is connected the second inductor (L'2) in B filter reactor, the second electric capacity (C'2) in B filter successively with the contact of the 4th IGBT switching tube (T'4); The 5th IGBT switching tube (T'5) in B two level current transformer and the contact of the 2nd IGBT switching tube (T'2) are connected the 3rd inductor (L'3) in B filter reactor, the 3rd electric capacity (C'3) in B filter successively; The electric current flowing through B inductor (L'1-L'3) and the electric current flowing through A inductor (L1-L3) intersect.