CN109390925B - Inverter lightning protection method, circuit and device and inverter grid-connected system - Google Patents
Inverter lightning protection method, circuit and device and inverter grid-connected system Download PDFInfo
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- CN109390925B CN109390925B CN201910004479.9A CN201910004479A CN109390925B CN 109390925 B CN109390925 B CN 109390925B CN 201910004479 A CN201910004479 A CN 201910004479A CN 109390925 B CN109390925 B CN 109390925B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
- H02H9/041—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage using a short-circuiting device
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
- H02H9/06—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage using spark-gap arresters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
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Abstract
The invention provides a method, a circuit and a device for protecting an inverter from lightning and a grid-connected system of the inverter, wherein the device connected between a power grid phase line and a power grid zero line in the inverter lightning protection circuit is provided with a first surge protector and a second surge protector; under the condition of removing a voltage dependent resistor in an EMC filter circuit, if high voltage is generated due to lightning stroke and the inverter is in poor grounding, the current flows through a ground path of a phase line of a power grid, because a first surge protector is a voltage-limiting surge protection device and has conduction voltage drop, and a second surge protector is a switch-type surge protection device and has conduction voltage drop approaching zero, the residual voltage which needs to be borne by an X capacitor in the EMC filter circuit is only the conduction voltage drop of one voltage-limiting surge protection device, the performance does not need to be increased, and the problem of inverter cost increase caused by the need of increasing the performance of the X capacitor in the prior art is solved.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a lightning protection method, a circuit and a device for an inverter and a grid-connected system of the inverter.
Background
The ac lightning protection topology of the prior art single-phase inverter, including the varistors MOV2 and MOV3 and the GAS discharge tube GAS, is shown within the dashed box in fig. 1; when higher voltage is generated due to lightning stroke, the lightning stroke current of the power grid phase line L to the ground is to the ground through the piezoresistor MOV2 and the GAS discharge tube GAS, and the lightning stroke current of the power grid zero line N to the ground is to the ground through the piezoresistor MOV3 and the GAS discharge tube GAS, so that the alternating current lightning protection effect on the single-phase inverter is realized.
In the single-phase inverter EMC (electromagnetic Compatibility) filter circuit, the varistor MOV1 connected between the grid phase line L and the grid neutral line N is liable to cause a problem of failure and fire due to aging leakage current, so that if the varistor MOV1 can be removed, the system reliability can be improved.
However, when the varistor MOV1 is removed, if there is a lightning strike current on the grid phase line L when the single-phase inverter has a relatively large ground resistance (poor ground), i.e. R2< < R1, the path through which the lightning strike current flows will be: l → MOV2 → MOV3 → N → R2 → PE; at this time, the X capacitor C1 in the EMC filter circuit needs to bear a relatively large residual voltage (voltage generated on the voltage dependent resistor after lightning current passes through the voltage dependent resistor), i.e. the series residual voltage of the voltage dependent resistors MOV2 and MOV 3; since a conventional X capacitor will burst due to the failure to withstand such a large residual voltage, the removal of the varistor MOV1 means that the performance of the X capacitor needs to be increased, which undoubtedly increases the cost of the inverter.
Disclosure of Invention
The invention provides a lightning protection method, a circuit and a device for an inverter and a grid-connected system for the inverter, and aims to solve the problem that in the prior art, the inverter cost is increased due to the fact that the voltage dependent resistor between a phase line L and a zero line N of a power grid is removed, and the requirement for increasing the performance of an X capacitor is brought.
In order to achieve the purpose, the technical scheme provided by the application is as follows:
an inverter lightning protection method is applied to an inverter lightning protection circuit, and the inverter lightning protection circuit comprises the following steps: the first surge protector and the second surge protector are connected between a phase line and a zero line of a power grid, the first surge protector is a voltage-limiting surge protection device, and the second surge protector is a switch-type surge protection device; the lightning protection method for the inverter comprises the following steps:
under the condition that the grounding resistance of the inverter is larger than a first preset value, if the voltages at two ends of the first surge protector and the second surge protector are larger than the sum of the conducting voltages of the first surge protector and the second surge protector, the first surge protector and the second surge protector are conducted;
and the ground current of the power grid phase line flows into the ground from the power grid zero line after passing through the first surge protector and the second surge protector.
Preferably, the inverter lightning protection circuit further comprises a third surge protector; the inverter lightning protection method further comprises the following steps:
under the condition that the grounding resistance of the inverter is smaller than a second preset value, if the voltages at the two ends of the first surge protector and the third surge protector are larger than the sum of the conducting voltages of the first surge protector and the third surge protector, the first surge protector and the third surge protector are conducted; if the voltages at the two ends of the second surge protector and the third surge protector are greater than the sum of the conducting voltages of the second surge protector and the third surge protector, the second surge protector and the third surge protector are conducted; the second preset value is smaller than the first preset value;
the ground current of the phase line of the power grid flows into the ground through the inverter ground resistor after passing through the first surge protector and the third surge protector; and after the ground current of the zero line of the power grid passes through the second surge protector and the third surge protector, the ground current flows into the ground through the grounding resistor of the inverter.
An inverter lightning protection circuit comprising: a first surge protector, a second surge protector and a third surge protector; wherein:
one end of the first surge protector is connected with a power grid phase line;
one end of the second surge protector is connected with a zero line of a power grid;
the other end of the first surge protector and the other end of the second surge protector are both connected with one end of the third surge protector;
the other end of the third surge protector is grounded through a resistor;
the first surge protector is a voltage-limiting surge protection device, and the second surge protector is a switch-type surge protection device.
Optionally, the number of the first surge protectors is the same as the number of the power grid phase lines.
Optionally, the first surge protector is a varistor; the second surge protector is a gas discharge tube.
Optionally, the third surge protector is a voltage-limiting surge protection device, or a switching surge protection device.
Optionally, the third surge protector is a varistor, or a gas discharge tube.
An inverter lightning protection device comprising: electromagnetic compatibility EMC filter circuit and as described in any one of the above inverter lightning protection circuits.
Optionally, the EMC filter circuit includes: the circuit comprises a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a first fuse, a second fuse and a common mode inductor; wherein:
the first capacitor is connected between the power grid phase line and the power grid zero line;
the second capacitor is connected between a power grid phase line and the ground;
the third capacitor is connected between the zero line of the power grid and the ground;
the first fuse is arranged on a power grid phase line; one end of the first fuse is connected with the first capacitor and the second capacitor, and the other end of the first fuse is connected with one end of a first winding of the common mode inductor;
the second fuse is arranged on a zero line of the power grid; one end of the second fuse is connected with the first capacitor and the third capacitor, and the other end of the second fuse is connected with one end of a second winding of the common mode inductor;
the other end of the first winding is grounded through the fourth capacitor;
the other end of the second winding is grounded through the fifth capacitor.
An inverter grid-connected system comprises the inverter lightning protection device.
The invention provides a lightning protection method for an inverter, wherein a first surge protector and a second surge protector are arranged on devices connected between a phase line and a zero line of a power grid in a lightning protection circuit of the inverter; under the condition of removing a voltage dependent resistor in an EMC filter circuit, if high voltage is generated due to lightning stroke and the inverter is in poor grounding, the current flows through a ground path of a phase line of a power grid, because a first surge protector is a voltage-limiting surge protection device and has conduction voltage drop, and a second surge protector is a switch-type surge protection device and has conduction voltage drop approaching zero, the residual voltage which needs to be borne by an X capacitor in the EMC filter circuit is only the conduction voltage drop of one voltage-limiting surge protection device, the performance does not need to be increased, and the problem of inverter cost increase caused by the need of increasing the performance of the X capacitor in the prior art is solved.
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 circuit diagram of a prior art inverter lightning protection circuit;
fig. 2 is a schematic structural diagram of an inverter lightning protection circuit according to an embodiment of the present invention;
fig. 3a is a flowchart of an inverter lightning protection method according to an embodiment of the present invention;
fig. 3b is another flowchart of a lightning protection method for an inverter according to an embodiment of the present invention;
fig. 4a is a circuit diagram of an example of an inverter lightning protection circuit applied to a single-phase inverter according to an embodiment of the present invention;
fig. 4b is a circuit diagram of an example of an inverter lightning protection circuit applied to a three-phase inverter according to an embodiment of the present invention;
fig. 5a is a diagram of another example of an inverter lightning protection circuit applied to a single-phase inverter according to an embodiment of the present invention;
fig. 5b is a diagram of another example of an inverter lightning protection circuit applied to a three-phase inverter according to an embodiment of the present invention;
fig. 6 is a circuit diagram of an inverter lightning protection device according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, 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 application.
In order to solve the problem that the performance of an X capacitor is increased due to the fact that a piezoresistor between a phase line L and a zero line N of a power grid is removed in the prior art, and the cost of an inverter is increased, the invention provides a lightning protection method of the inverter, which is applied to a lightning protection circuit of the inverter; as shown in fig. 2, the inverter lightning protection circuit includes: the surge protection device comprises a first surge protection device 101 and a second surge protection device 102 which are connected between a phase line and a zero line of a power grid, wherein the first surge protection device 101 is a voltage-limiting type surge protection device, and the second surge protection device 102 is a switch type surge protection device.
Referring to fig. 3a, the method for protecting an inverter from lightning includes:
s101, under the condition that the grounding resistance of the inverter is larger than a first preset value, if the voltages at two ends of the first surge protector and the second surge protector are larger than the sum of the conducting voltages of the first surge protector and the second surge protector, the first surge protector and the second surge protector are conducted;
when the inverter has poor grounding and the like, the grounding resistance (such as the resistor R1 in fig. 2) of the inverter is larger than a first preset value, and the first preset value can be a value far larger than the resistance value of the resistor R2, at this time, R2< < R1, and a voltage difference is likely to be generated between the grid phase line L and the grid zero line N; originally, this voltage difference will lead to the varistor that lies in between electric wire netting phase line L and electric wire netting zero line N among the EMC filter circuit to switch on, and then realizes discharging to the thunderbolt energy through electric wire netting zero line. However, after the voltage dependent resistor between the phase line L and the zero line N of the power grid is removed, the voltage difference, i.e. the voltages at the two ends of the first surge protector and the second surge protector, will exceed the sum of the conduction voltages of the two surge protectors, so that the two surge protectors are conducted to generate current.
S102, the ground current of the power grid phase line flows into the ground from the power grid zero line after passing through the first surge protector and the second surge protector.
In fig. 2, if the first surge protector 101 and the second surge protector 102 are turned on, the flow path of the current flowing through the power line L to the ground will be: l → 101 → 102 → N → R2 → PE; the residual voltage that X capacitor C1 in the EMC filter circuit needs to bear at this time is the sum of the conduction voltage drops of first surge protector 101 and second surge protector 102.
Because the first surge protector 101 is a voltage-limiting surge protector and has conduction voltage drop, and the second surge protector 102 is a switch-type surge protector and has conduction voltage drop approaching zero, the residual voltage that the X capacitor C1 needs to bear is only the conduction voltage drop of one voltage-limiting surge protector, and performance does not need to be increased, thereby avoiding the problem that the cost of the inverter is increased due to the need of increasing the performance of the X capacitor in the prior art.
Preferably, as shown in fig. 2, the inverter lightning protection circuit further includes a third surge protector 103; as shown in fig. 3b, the method for protecting an inverter from lightning also includes, based on fig. 3 a:
s103, under the condition that the grounding resistance of the inverter is smaller than a second preset value, if the voltages at the two ends of the first surge protector and the third surge protector are larger than the sum of the conducting voltages of the first surge protector and the third surge protector, the first surge protector and the third surge protector are conducted; if the voltages at the two ends of the second surge protector and the third surge protector are greater than the sum of the breakover voltages of the second surge protector and the third surge protector, the second surge protector and the third surge protector are conducted; the second preset value is smaller than the first preset value;
s104, after the ground current of the power grid phase line passes through the first surge protector and the third surge protector, the ground current flows into the ground through the grounding resistor of the inverter; and after passing through the second surge protector and the third surge protector, the ground current of the zero line of the power grid flows into the ground through the grounding resistor of the inverter.
The grounding resistance of the inverter is smaller than a second preset value, the second preset value can be a value far smaller than the resistance value of the resistor R2, at the moment, R1< < R2, if a high voltage is generated due to lightning stroke, the grounding current of the power grid phase line L will pass through the first surge protector 101 and the third surge protector 103 to the ground, and the grounding current of the power grid zero line N will pass through the second surge protector 102 and the third surge protector 103 to the ground.
The first preset value and the second preset value are set mainly to represent the resistance magnitude relationship between the resistors R1 and R2 in fig. 2, so the specific selection values of the two resistors R1 and R2 may be determined according to the application environment, and are not specifically limited herein and are within the protection scope of the present application.
Another embodiment of the present invention further provides an inverter lightning protection circuit, please refer to fig. 2, which takes a single-phase inverter as an example for description, and the inverter lightning protection circuit includes: a first surge protector device 101, a second surge protector device 102, and a third surge protector device 103; wherein:
one end of the first surge protector 101 is connected with a power grid phase line L;
one end of the second surge protector 102 is connected with a zero line N of the power grid;
the other end of the first surge protector 101 and the other end of the second surge protector 102 are both connected with one end of a third surge protector 103;
the other end of the third surge protector 103 is grounded PE through a resistor R1;
the network zero line N is also connected to ground PE via a resistor R2.
The first surge protector 101 is a voltage-limiting surge protector, and the second surge protector 102 is a switching surge protector. The third surge protector 103 may be a voltage-limiting surge protector, or may be a switching surge protector, which is not limited in this respect.
As shown in fig. 2, a single-phase inverter is taken as an example for explanation, and the specific operation principle is as follows:
when a high voltage is generated due to lightning strike, the ground current of the phase line L of the power grid will pass through the first surge protector 101 and the third surge protector 103 to the ground, and the ground current of the zero line N of the power grid will pass through the second surge protector 102 and the third surge protector 103 to the ground.
After removing the voltage dependent resistor in the EMC filter circuit, when the single-phase inverter has a relatively large ground resistance, for example, when the ground is not good, i.e. R2< < R1, if there is a lightning strike current on the power grid phase line L, the path through which the lightning strike current flows will be: l → 101 → 102 → N → R2 → PE; the residual voltage that X capacitor C1 in the EMC filter circuit needs to bear at this time is the sum of the conduction voltage drops of first surge protector 101 and second surge protector 102. Because the first surge protector 101 is a voltage-limiting surge protector and has conduction voltage drop, and the second surge protector 102 is a switch-type surge protector and has conduction voltage drop approaching zero, the residual voltage that the X capacitor C1 needs to bear is only the conduction voltage drop of one voltage-limiting surge protector, and performance does not need to be increased, thereby avoiding the problem that the cost of the inverter is increased due to the need of increasing the performance of the X capacitor in the prior art.
In the inverter lightning protection circuit provided by this embodiment, the connecting devices between the power grid phase line L and the power grid zero line N are the first surge protection device 101 and the second surge protection device 102, the first surge protection device 101 is selected as a voltage limiting type surge protection device, and the second surge protection device 102 is selected as a switch type surge protection device, so as to reduce the residual voltage between the power grid phase line L and the power grid zero line N, and further reduce the withstand voltage level of the device connected in parallel between the power grid phase line L and the power grid zero line N in the rear-stage circuit. That is, under the condition that the inverter grounding resistance is relatively large (for example, poor grounding), the inverter can be grounded through the first surge protector 101, the second surge protector 102 and the resistor R2, so that the voltage dependent resistor in the EMC filter circuit arranged between the power grid phase line L and the power grid zero line N is removed, and meanwhile, only one device in a current loop forms residual voltage due to lightning stroke, so that the requirement on a rear-stage device is low, the performance of an X capacitor is not required to be increased, the reliability is improved, and the system construction cost is indirectly reduced.
On the basis of the above embodiment and fig. 2, several specific implementation forms are provided in another embodiment of the present invention, as shown in fig. 4a to fig. 5 b.
Because the first surge protector 101 is a voltage-limiting surge protector, the second surge protector 102 is a switch-type surge protector, and the third surge protector 103 can be selected to adopt the voltage-limiting surge protector, or can also adopt the switch-type surge protector; in practical applications, there are many alternatives for the selection of the individual surge protectors, such as:
optionally, the first surge protector 101 is a varistor, such as MOV1 shown in fig. 4 a-5 b.
Optionally, the second surge protector 102 is a GAS discharge tube, such as GAS shown in fig. 4a and 4b and GAS1 shown in fig. 5a and 5 b.
Optionally, the third surge protector 103 is a varistor, such as MOV2 shown in fig. 4a and 4 b; alternatively, the third surge protector 103 may be a GAS discharge tube, such as GAS2 shown in fig. 5a and 5 b.
In addition, in practical application, the voltage-limiting surge protection device is not limited to a voltage dependent resistor, and a suppression diode and the like can be adopted; for the switch type surge protection device, the device is not limited to a gas discharge tube, and a discharge gap, a silicon controlled rectifier or a three-terminal bidirectional silicon controlled element and the like can be adopted; depending on the specific application environment, are all within the scope of protection of the present application.
It should be noted that the number of the first surge protectors 101 is the same as the number of the grid phases.
As shown in fig. 2, 4a and 5a, the number of the first surge protectors 101 and the number of the power line phases L are both 1 in the inverter lightning protection circuit applied to the single-phase inverter; as shown in fig. 4b and 5b, the number of the first surge protectors 101 and the number of the grid lines (L1, L2, L3) are 3 in the inverter lightning protection circuit applied to the three-phase inverter.
The topology shown in fig. 4a is taken as an example for explanation:
the network phase line L is connected to the network neutral line N via a varistor MOV1 and a GAS discharge tube GAS. Under the condition that the grounding resistance of the inverter is relatively large (for example, poor grounding), namely R2< < R1, if the power grid phase line L has lightning current to the ground, and because the resistor R1 is relatively large, the lightning current passes through the varistor MOV1, the GAS discharge tube GAS, the power grid zero line N and the resistor R2 from the power grid phase line L to the ground PE, at this time, because the voltage drop of the GAS discharge tube GAS after being conducted is almost 0, the residual voltage between the power grid phase line L and the power grid zero line N is the residual voltage of one device, namely the varistor MOV1, and further, the model selection upgrading and the cost increase of the X capacitor caused by EMC between the power grid phase line L and the power grid zero line N are greatly reduced.
In fig. 4a, the grid phase line L is connected to ground PE via varistors MOV1 and MOV 2. In the case of good inverter grounding, i.e. R1< < R2, when there is a lightning current on the grid phase line L to ground, this lightning current goes from the grid phase line L to ground through the varistors MOV1 and MOV2 and the resistor R1; at the moment, the residual voltage of the power phase line L to the ground is a conducting voltage drop generated by two voltage-sensitive devices, namely MOV1 and MOV 2; however, because the EMC measure added between the phase line L of the power grid and the ground is generally a Y capacitor (as shown in C2 in fig. 6), and the Y capacitor can bear a large pulse voltage compared with the X capacitor, the performance of the Y capacitor is generally not required to be increased, and even if the performance is required to be increased, the performance is easily achieved without increasing too much cost. Moreover, because two voltage dependent resistors are arranged between the phase line L of the power grid and the ground, when one voltage dependent resistor fails due to aging, the two voltage dependent resistors are not continuously on fire, and a dual redundancy effect is achieved.
In fig. 4a, the mains neutral N is led via a GAS discharge tube GAS and a varistor MOV2 and a resistor R1 to ground PE. When the inverter is well grounded, namely R1< < R2, the inverter is equivalent to the far end of the power grid zero line N being grounded, if the power grid zero line N has a lightning stroke current to the ground nearby, the lightning stroke current passes through the GAS discharge tube GAS, the voltage dependent resistor MOV2 and the resistor R1 from the power grid zero line N to the ground PE due to the fact that the resistor R2 is large, and protection can be achieved.
The topology shown in fig. 4b is taken as an example for explanation:
the network phase line L1 is connected to the network neutral line N through a voltage dependent resistor MOV1 and a GAS discharge tube GAS. Under the condition that the grounding resistance of the inverter is relatively large, namely R2< < R1, if the power line L1 has lightning current to the ground, the lightning current passes through the voltage dependent resistor MOV1, the GAS discharge tube GAS, the power line zero line N and the resistor R2 from the power line L1 to the ground PE because the resistor R1 is relatively large; at this time, because the voltage of the GAS discharge tube GAS after conduction is almost 0, the residual voltage between the power grid phase line L and the power grid zero line N is the residual voltage of a single MOV1 device, so that the model selection upgrading and the cost increase of the X capacitor caused by EMC between the power grid phase line L and the power grid zero line N are greatly reduced.
In fig. 4b, the grid phase line L1 is connected to ground PE via the voltage dependent resistors MOV1 and MOV 2. In the case of good inverter grounding, i.e. R1< < R2, if there is a lightning strike current on the grid phase line L1 to ground, then this lightning strike current L passes through the varistors MOV1 and MOV2 and the resistor R1 to ground PE; at the moment, the residual voltage of the power phase line L1 to the ground is a conducting voltage drop generated by two voltage-sensitive devices, namely MOV1 and MOV 2; however, because the EMC measure added between the phase line L of the power grid and the ground is generally a Y capacitor, and compared with the X capacitor, the Y capacitor can bear a large pulse voltage, the performance of the Y capacitor generally does not need to be increased, and even if the EMC measure needs to be increased, the EMC measure is easily implemented without increasing too much cost. Moreover, because two voltage dependent resistors are arranged between the power grid phase line L1 and the ground, when one of the voltage dependent resistors fails due to aging, the voltage dependent resistor is unlikely to continuously catch fire, and a dual redundancy effect is achieved.
In fig. 4b the mains neutral N is led via a GAS discharge tube GAS and a varistor MOV2 and a resistor R1 to ground PE. When the inverter is well grounded, namely R1< < R2, the inverter is equivalent to the far end of the power grid zero line N being grounded, if the power grid zero line N has a lightning stroke current to the ground nearby, the lightning stroke current passes through the GAS discharge tube GAS, the voltage dependent resistor MOV2 and the resistor R1 from the power grid zero line N to the ground PE due to the fact that the resistor R2 is large, and protection can be achieved.
The principle of lightning strike leakage of grid phase line L2 to ground and grid phase line L3 to ground, and the principle of lightning strike leakage in fig. 5a and 5b are the same as the above-mentioned principle of lightning strike leakage of grid phase line L1 to ground, and are not described in detail here.
The rest of the structure and the principle are the same as those of the above embodiments, and are not described herein again.
Another embodiment of the present invention further provides an inverter lightning protection device, as shown in fig. 6, including: EMC filter circuit 200 and inverter lightning protection circuit 100 as described in any of the embodiments above.
Optionally, the EMC filter circuit 100 includes: a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a first fuse F1, a second fuse F2 and a common mode inductor L1; wherein:
the first capacitor C1 is connected between the power grid phase line L and the power grid zero line N;
the second capacitor C2 is connected between the power line phase L and the ground;
the third capacitor C3 is connected between the zero line N of the power grid and the ground;
the first fuse F1 is arranged on a power grid phase line L; one end of the first fuse F1 is connected with the first capacitor C1 and the second capacitor C2, and the other end is connected with one end of the first winding of the common mode inductor L1;
the second fuse F2 is arranged on the zero line N of the power grid; one end of the second fuse F2 is connected with the first capacitor C1 and the third capacitor C3, and the other end is connected with one end of the second winding of the common mode inductor L1;
the other end of the first winding is grounded through a fourth capacitor C4;
the other end of the second winding is connected to ground via a fifth capacitor C5.
In practical applications, the first fuse F1 and the second fuse F2 can be fuses.
Through the inverter lightning protection circuit 100, a piezoresistor originally arranged between a phase line L and a zero line N of a power grid can be removed from the EMC filter circuit 200, so that the cost is saved; the specific working principle of the inverter lightning protection circuit 100 is as described in the above embodiments, and is not described in detail herein.
Another embodiment of the present invention further provides an inverter grid-connected system, including the inverter lightning protection device according to the above embodiment.
The inverter lightning protection device is arranged between the inverter and the power grid, and the specific structure and the working principle of the inverter lightning protection device are the same as those of the embodiment, and are not repeated here.
The embodiments of the invention are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments can be referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner. Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make numerous possible variations and modifications to the present teachings, or modify equivalent embodiments to equivalent variations, without departing from the scope of the present teachings, using the methods and techniques disclosed above. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the scope of the protection of the technical solution of the present invention, unless the contents of the technical solution of the present invention are departed.
Claims (6)
1. An inverter lightning protection device, comprising: the system comprises an electromagnetic compatibility EMC filter circuit and an inverter lightning protection circuit;
the EMC filter circuit includes: the circuit comprises a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a first fuse, a second fuse and a common mode inductor; wherein:
the first capacitor is connected between the power grid phase line and the power grid zero line;
the second capacitor is connected between a power grid phase line and the ground;
the third capacitor is connected between the zero line of the power grid and the ground;
the first fuse is arranged on a power grid phase line; one end of the first fuse is connected with the first capacitor and the second capacitor, and the other end of the first fuse is connected with one end of a first winding of the common mode inductor;
the second fuse is arranged on a zero line of the power grid; one end of the second fuse is connected with the first capacitor and the third capacitor, and the other end of the second fuse is connected with one end of a second winding of the common mode inductor;
the other end of the first winding is grounded through the fourth capacitor;
the other end of the second winding is grounded through the fifth capacitor;
the inverter lightning protection circuit includes: a first surge protector, a second surge protector and a third surge protector; wherein:
one end of the first surge protector is connected with a power grid phase line;
one end of the second surge protector is connected with a zero line of a power grid;
the other end of the first surge protector and the other end of the second surge protector are both connected with one end of the third surge protector;
the other end of the third surge protector is grounded through a resistor;
first surge protector is voltage limiting type surge protection device, second surge protector is switching mode surge protection device, makes in the EMC filter circuit under the condition of not connecting in the piezo-resistor between electric wire netting phase line and electric wire netting zero line, when the dc-to-ac converter ground fault and electric wire netting phase line have lightning current to ground, the voltage that first electric capacity need bear is only one voltage limiting type surge protection device's the voltage drop that switches on.
2. The inverter lightning protection device according to claim 1, wherein the number of the first surge protectors is the same as the number of the grid phase lines.
3. The inverter lightning protection device of claim 1, wherein the first surge protector is a varistor; the second surge protector is a gas discharge tube.
4. The inverter lightning protection device according to claim 1, wherein the third surge protector is a voltage-limiting type surge protection device or a switching type surge protection device.
5. The inverter lightning protection device according to claim 4, wherein the third surge protector is a varistor or a gas discharge tube.
6. An inverter grid-connected system characterized by comprising the inverter lightning protection device according to any one of claims 1 to 5.
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| CN113438785A (en) * | 2021-06-18 | 2021-09-24 | 浙江国研智能电气有限公司 | Power supply for bulb tube filament of high-voltage X-ray machine |
| CN113872433A (en) * | 2021-10-15 | 2021-12-31 | 青岛鼎信通讯股份有限公司 | Topology for improving anti-surge capacity of LCL type grid-connected inverter |
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| CN201048288Y (en) * | 2007-03-12 | 2008-04-16 | 叶林 | Simple earthing 220V 2-port 3-module power supply surge protector |
| KR100941962B1 (en) * | 2008-09-03 | 2010-02-12 | 유)엔텍코리아 | Surge protector |
| CN103199516B (en) * | 2013-03-20 | 2016-01-27 | 华为技术有限公司 | A kind of interchange protection circuit and system thunder defending circuit |
| US20160087424A1 (en) * | 2014-09-23 | 2016-03-24 | Nidec Motor Corporation | Powerline surge protection |
| CN104882870B (en) * | 2015-03-03 | 2018-03-09 | 华为技术有限公司 | A kind of lightning protection circuit |
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