CN116819400B - Inverter N line detection control circuit and method thereof - Google Patents
Inverter N line detection control circuit and method thereof Download PDFInfo
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- CN116819400B CN116819400B CN202311091445.0A CN202311091445A CN116819400B CN 116819400 B CN116819400 B CN 116819400B CN 202311091445 A CN202311091445 A CN 202311091445A CN 116819400 B CN116819400 B CN 116819400B
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- 238000001514 detection method Methods 0.000 title claims abstract description 29
- 238000000034 method Methods 0.000 title claims abstract description 14
- 230000002159 abnormal effect Effects 0.000 claims abstract description 20
- 238000001914 filtration Methods 0.000 claims abstract description 14
- 238000005070 sampling Methods 0.000 claims abstract description 12
- 239000003990 capacitor Substances 0.000 claims description 69
- 238000004146 energy storage Methods 0.000 claims description 4
- 238000010586 diagram Methods 0.000 description 7
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
- H02M7/53875—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with analogue control of three-phase output
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/58—Testing of lines, cables or conductors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/66—Testing of connections, e.g. of plugs or non-disconnectable joints
-
- 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
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
- H02M7/53873—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with digital control
Abstract
The embodiment of the invention discloses an inverter N line detection control circuit and a method thereof, wherein the circuit comprises: the sampling module is used for collecting three-phase voltages; the filtering module is connected among an L1 line, an L2 line, an L3 line and an N line of the three-phase inverter; the controlled module is connected between any one of the L1 line, the L2 line and the L3 line and the N line, and when the controlled module is conducted, the X capacitance capacity of the line pair N line connected with the controlled module is larger than that of the other two lines; and the control module is configured to control the on/off of the controlled module according to the output mode, and judge whether the N line is connected to the power grid by comparing the phase angle difference value of the three-phase voltage with a preset angle range. According to the invention, the capacitance capacity of any one of three lines of the inverter is controlled to be changed to the N line, and the N line is detected, so that the inverter can acquire the information of abnormal connection of the N line under the condition that the set output mode is different from the actual line system, and the safety and reliability of the inverter are improved.
Description
Technical Field
The embodiment of the invention relates to the field of inverter detection, in particular to an inverter N-line detection control circuit and an inverter N-line detection control method.
Background
In a three-phase grid, IEC standard ground systems can be divided into three-phase three-wire (TN-C, IT) and three-phase four-wire (TN-S, TN-S-C, TT), where three-phase three-wire is suitable for systems that balance loads and three-phase four-wire is suitable for systems that unbalance loads.
Before grid connection of the three-phase inverter, an output mode of the three-phase inverter is generally required to be set, and three-phase three-wire or three-phase four-wire is selected to match different loads or grid connection requirements. If the set output mode is inconsistent with the actual connection line, overvoltage and overcurrent of the three-phase inverter can be caused, so that the load is damaged, or personal safety risks are brought.
Disclosure of Invention
In order to solve the technical problems, one technical scheme adopted by the embodiment of the invention is as follows: there is provided an inverter N-line detection control circuit applied to an energy storage system including a three-phase inverter, the circuit including: the sampling module is used for collecting three-phase voltages of the three-phase inverter; the filtering module is connected among the L1 line, the L2 line, the L3 line and the N line of the three-phase inverter and used for filtering electromagnetic interference; the controlled module is connected among any one of the L1 line, the L2 line and the L3 line and the N line, and when the controlled module is conducted, the X capacitance capacity of the line connected with the controlled module to the N line is larger than that of the other two lines to the N line; and the control module is configured to control the on/off of the controlled module according to the output mode of the three-phase inverter, and judge whether the N line is connected to a power grid or not by comparing the phase angle difference value of the three-phase voltage with a preset angle range.
In some embodiments, the output modes include a three-phase three-wire mode and a three-phase four-wire mode.
In some embodiments, if the output mode is a three-phase four-wire mode, the control module controls the controlled module to be turned on, and determines whether the N-wire is not connected to the power grid by comparing the phase angle difference with a first preset angle range; if the output mode is a three-phase three-wire mode, the control module controls the controlled module to be disconnected, and judges whether the N wire is connected into the power grid by mistake by comparing the phase angle difference value with a second preset angle range.
In some embodiments, the filtering module includes a capacitor C11, a capacitor C12, and a capacitor C13, wherein the capacitor C11 is connected between the L1 line and the N line; the capacitor C12 is connected between the L2 line and the N line; the capacitor C13 is connected between the L3 line and the N line.
In some embodiments, the controlled module includes a capacitor C38 and a relay, wherein a first end of the capacitor C38 is connected to the N-line, a second end of the capacitor C38 is connected to a first end of the relay, a second end of the relay is connected to the L1-line, the L2-line, or the L3-line, and a controlled end of the relay is connected to the control module.
In some embodiments, the controlled module comprises a capacitor C38, a MOS transistor Q37, and a MOS transistor Q38, wherein a first end of the capacitor C38 is connected to the N line, a second end of the capacitor C38 is connected to a source of the MOS transistor Q38, and a source of the MOS transistor Q37 is connected to the L1 line, the L2 line, or the L3 line; the drain electrode of the MOS tube Q38 and the drain electrode of the MOS tube Q37 are grounded, and the grid electrode of the MOS tube Q38 and the grid electrode of the MOS tube Q37 are connected to the control module.
In some embodiments, the control module comprises a DSP unit and a relay control unit, wherein an input of the DSP unit is connected to an output of the sampling module, an output of the DSP unit is connected to an output of the relay control unit, and an output of the relay control unit is connected to the controlled module.
In some embodiments, if the controlled module is connected to the L1 line, the phase angle difference is calculated by the control module according to:
，
wherein C1 is the sum of the capacitance C11 and the capacitance X of the controlled module, and C0 is the capacitance C11, C12 or C13;
if the controlled module is connected to the L2 line, the phase angle difference is calculated by the control module according to the following formula:
，
wherein C2 is the sum of capacitance C12 and X capacitance of the controlled module;
if the controlled module is connected to the L3 line, the phase angle difference is calculated by the control module according to the following equation:
，
wherein C3 is the sum of the capacitance C13 and the X capacitance of the controlled module.
In order to solve the technical problems, another technical scheme adopted by the embodiment of the invention is as follows: the inverter N line detection control method is applied to the inverter N line detection control circuit, and specifically comprises the following steps: the control module judges whether a preset output mode is a three-phase four-wire mode or a three-phase three-wire mode; if the output mode is a three-phase four-wire mode, the control module controls the controlled module to be conducted, and judges whether the N wires are not connected into a power grid or not by comparing the phase angle difference value with a first preset angle range; if the output mode is a three-phase three-wire mode, the control module controls the controlled module to be disconnected, and judges whether the N wire is connected into the power grid by mistake by comparing the phase angle difference value with a second preset angle range.
In some embodiments, the comparing the phase angle difference with a first preset angle range to determine whether the N line is not connected to the power grid includes: calculating the first phase angle difference according to the acquired three-phase voltage; judging whether the first phase angle difference exceeds the first preset angle range and the duration exceeds preset first time; if yes, determining that the first phase angle difference is abnormal, wherein the N lines are not connected to the power grid; if not, determining that the first phase angle difference is not abnormal, wherein the N lines are connected to the power grid; and if the N lines are not connected to the power grid, enabling the three-phase inverter to enter a standby state.
In some embodiments, the determining whether the N line is erroneously connected to the power grid by comparing the phase angle difference with a second preset angle range includes: calculating the second phase angle difference according to the acquired three-phase voltage; judging whether the second phase angle difference exceeds the second preset angle range and the duration exceeds a preset second time; if yes, determining that the second phase angle difference is abnormal, and accessing the power grid by mistake through the N lines; if not, determining that the second phase angle difference is not abnormal, wherein the N line is not connected to the power grid; and if the N lines are connected into the power grid by mistake, enabling the three-phase inverter to enter a standby state.
The beneficial effects of the embodiment of the invention are as follows: compared with the prior art, the embodiment of the invention detects the N line by controlling and changing the capacitance capacity of any one of the three lines of the inverter to the N line, so that the inverter can acquire the information of abnormal connection of the N line and protect the inverter under the condition that the set output mode is different from the actual line system, thereby improving the safety and the reliability of the inverter.
Drawings
Fig. 1 is a schematic structural diagram of an inverter N-line detection control circuit according to an embodiment of the present invention;
fig. 2 is a circuit diagram of an inverter N-line detection control circuit according to an embodiment of the present invention, showing a circuit configuration of a controlled module;
fig. 3 is a circuit diagram of another inverter N-line detection control circuit according to an embodiment of the present invention, showing a circuit configuration of another controlled module;
FIG. 4 is a three-phase vector diagram of three-phase voltages;
fig. 5 is a schematic flow chart of an inverter N-line detection control method according to an embodiment of the present invention;
fig. 6 is a schematic flow chart of step S200 provided in the embodiment of the present invention;
fig. 7 is a schematic flow chart of step S300 according to an embodiment of the present invention.
Detailed Description
In order to facilitate an understanding of the present application, the present application will be described in more detail below with reference to the accompanying drawings and specific examples. It will be understood that when an element is referred to as being "fixed" to another element, it can be directly on the other element or one or more intervening elements may be present therebetween. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or one or more intervening elements may be present therebetween. The terms "upper," "lower," "inner," "outer," "bottom," and the like as used in this specification are used in an orientation or positional relationship based on that shown in the drawings, merely to facilitate the description of the present application and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the present application. Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the present application in this description is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used in this specification includes any and all combinations of one or more of the associated listed items.
In addition, the technical features described below in the different embodiments of the present application may be combined with each other as long as they do not collide with each other.
In some embodiments of the present application, an inverter N-line detection control circuit is provided, and the inverter N-line detection control circuit is applied to an energy storage system including a three-phase inverter, and a schematic structure of the inverter N-line detection control circuit is shown in fig. 1, where the energy storage system includes a sampling module 110, a filtering module 120, a control module 130, and a controlled module 140.
The sampling module 110 is correspondingly connected to the L1 line, the L2 line, the L3 line, and the N line of the three-phase inverter 20, and is configured to collect three-phase voltages of the three-phase inverter 20 and send the collected three-phase voltages to the control module 130.
The filtering module 120 is connected between the L1 line, the L2 line, the L3 line and the N line of the three-phase inverter 20, and is used for filtering electromagnetic interference. The filtering module 120 includes a plurality of X capacitors. The full name of X capacitance is generally called: x2 (X1/X3/MKP) suppresses electromagnetic interference of power supply. The functions in the circuit are mainly: and the power supply line crossing circuit, the EMI filtering and the spark eliminating circuit and the like ensure that the finished product of the electronic product meets the EMC requirement.
The controlled module 140 is connected between any one of the L1 line, the L2 line, and the L3 line and the N line of the three-phase inverter 20, i.e., a first end of the controlled module 140 is connected to the L1 line, the L2 line, or the L3 line, and a second end of the controlled module 140 is connected to the N line. The controlled end of the controlled module 140 is connected to the control module 130, and the controlled module 140 is turned on or off under the control of the control module 130. When the controlled module 140 is turned on, the X capacitance of the line pair N line connected to the controlled module 140 is larger than the X capacitance of the other two lines to the N line. Taking the L3 line as an example, if the first end of the controlled module 140 is connected to the L3 line, when the controlled module 140 is turned on, the X capacitance of the L3 line to the N line is greater than the X capacitance of the L1 line or the L2 line to the N line.
The control module 130 is configured to control the controlled module 140 to be turned on or off according to the output mode of the three-phase inverter 20, and determine whether the N line is connected to the power grid 30 by comparing the phase angle difference of the three-phase voltage with a preset angle range.
In some embodiments of the present application, the output modes include a three-phase three-wire mode and a three-phase four-wire mode.
In some embodiments of the present application, if the output mode is a three-phase four-wire mode, the control module 130 controls the controlled module 140 to be turned on, and determines whether the N wires are not connected to the power grid 30 by comparing the phase angle difference with the first preset angle range.
If the output mode is a three-phase three-wire mode, the control module 130 controls the controlled module to be turned off 140, and determines whether the N-wire is erroneously connected to the power grid 30 by comparing the phase angle difference with the second preset angle range.
Referring to fig. 2, fig. 2 is a circuit diagram of an inverter N-line detection control circuit according to an embodiment of the present application, and shows circuit diagrams of the filtering module 110 and the controlled module 140. As an example, the output mode of the inverter N-line detection control circuit is three-phase four-wire.
In some embodiments of the present application, the X capacitance in the filter module 110 is connected in a Y-type manner. Specifically, the filtering module 110 includes a capacitor C11, a capacitor C12, and a capacitor C13, where the capacitor C11 is connected between the L1 line and the N line; the capacitor C12 is connected between the L2 line and the N line; a capacitor C13 is connected between the L3 line and the N line. Under the condition that other capacitors are not connected, the capacitance of the capacitor C11, the capacitance of the capacitor C12 and the capacitance of the capacitor C13 are all equal.
In some embodiments of the present application, the control module 130 includes a digital signal processing (Digital Signal Process, DSP) unit 131 and a relay control unit 132, wherein an input of the DSP unit 131 is connected to an output of the sampling module 110, an output of the DSP unit 131 is connected to an output of the relay control unit 132, and an output of the relay control unit 132 is connected to the controlled module 140 (i.e., a controlled end of the relay 141 shown in fig. 2).
In some embodiments of the present application, the controlled module 140 is connected between the L3 line and the N line. The controlled module 140 includes a capacitor C38 and a relay 141, wherein a first end of the capacitor C38 is connected to the N line, a second end of the capacitor C38 is connected to a first end of the relay 141, a second end of the relay 141 is connected to the L3 line, and a controlled end of the relay 141 is connected to the control module 130 (i.e., an output end of the relay control unit 132 shown in fig. 2).
In other embodiments of the present application, the controlled module 140 may be connected between the L1 line or the L2 line and the N line, i.e., the first end of the capacitor C38 is connected to the N line, the second end of the capacitor C38 is connected to the first end of the relay 141, the second end of the relay 141 is connected to the L1 line or the L2 line, and the controlled end of the relay 141 is connected to the control module 130.
In the embodiment of the present application, the output mode of the N-line detection control circuit of the inverter is three-phase four-wire, so the DSP unit 131 needs to send a conducting signal to the relay control unit 132, so that the relay control unit 132 controls the relay 141 in the controlled module 140 to be conducted. So that the capacitor C38 is connected between the L3 line and the N line to change the X capacitance of the L3 line to the N line.
Let X capacitance of the capacitor C11, the capacitor C12, and the capacitor C13 be C0, and after the capacitor C38 is connected between the L3 line and the N line, the X capacitance of the L3 line to the N line is C3, c3=c13+c38. It is seen that C3 is greater than C0.
If the output mode of the inverter N-line detection control circuit is three-phase three-line, the DSP unit 131 needs to send an off signal to the relay control unit 132, so that the relay control unit 132 controls the relay 141 in the controlled module 140 to be turned off. The capacitance C38 is not connected between the L3 line and the N line, so the X capacitance of the L3 line to the N line remains unchanged and is still equal to the X capacitance of the L1 line or the L2 line to the N line.
Referring to fig. 4, fig. 4 is a three-phase vector diagram of three-phase voltages. When the wiring requirement is three-phase four-wire, i.e., N-wire is required, the DSP unit 131 makes the relay control unit 132 control the relay 141 in the controlled module 140 to be turned on, and the X capacitances of the L1 phase, the L2 phase, and the L3 phase with respect to N are unbalanced capacitances. If the N line is connected, the power grid 30 is used as a strong voltage source, and the N point is stable; when the N lines are disconnected, the N point voltage of the inverter is formed by three-phase voltage and three X capacitors, and is a virtual N point.
In fig. 4, the N point is the original neutral point of the power grid 30, i.e. the N line has access; and N' is a virtual neutral point of the internal unbalanced X capacitor structure, namely N line disconnection is not accessed. It can be seen that the line voltage of the three phases is not changed, but the origins of the L1 phase and the L2 phase are shifted, so that the included angle between the L2 phase and the L3 phase and the included angle between the L1 phase and the L3 phase are both larger than 120 degrees, and the included angle between the L1 phase and the L2 phase is smaller than 120 degrees.
Let the included angle between L1 phase and L2 phase be 2θ, the three-phase voltage be Va, the X capacitance of L1 phase and L2 relative to N be C0, the X capacitance of L3 relative to N be C3, the power grid frequency be f, the current of each phase be i l1 ,i l2 ,i l3 . When the N line is not connected, the KCL kirchhoff current law is known as follows:
，
since the current is the voltage divided by the capacitive reactance, it is possible to obtain:
，
the finishing method can obtain:
，
obtaining。
And 2 theta is the included angle between the L1 phase and the L2 phase, namely the phase angle difference value of the three-phase voltage. If the output mode is a three-phase four-wire mode, the DSP unit 131 determines whether the N-wire is not connected to the power grid 30 by comparing the phase angle difference with the first preset angle range. Specifically, it is determined whether the phase angle difference exceeds a first preset angle range and the duration exceeds a preset time. If yes, judging that the N lines are not connected into the power grid 30, and enabling the three-phase inverter 20 to be in a connection abnormal state so that the three-phase inverter 20 enters a standby state; if not, judging that the N lines are connected to the power grid 30, and the three-phase inverter 20 is in a normal running state.
In the present embodiment, the controlled module 140 is connected to the L3 line, and the phase angle difference is calculated by the control module 130 according to the following formula:
，
wherein C3 is the sum of the capacitance C13 and the capacitance X of the controlled module, and C0 is the capacitance C11, C12 or C13.
In other embodiments of the present application, if the controlled module 140 is connected to the L1 line, the phase angle difference is calculated by the control module 130 according to the following equation:
，
where C1 is the sum of the capacitance C11 and the X capacitance of the controlled module 140.
If the controlled module 140 is connected to the L2 line, the phase angle difference is calculated by the control module 130 according to the following equation:
，
where C2 is the sum of the capacitance C12 and the X capacitance of the controlled module 140.
In other embodiments of the present application, it may also be determined whether the N line is not connected to the power grid 30 by comparing the phase angle difference with the preset angle difference. Specifically, judging whether the phase angle difference 2 theta is smaller than a preset angle difference, if so, considering that the N line is not connected; if not, the N line is considered to be accessed.
If the output mode is a three-phase three-wire mode, the DSP unit 131 determines whether the N-wire is erroneously connected to the power grid 30 by comparing the phase angle difference with the second preset angle range. Specifically, it is determined whether the phase angle difference exceeds a second preset angle range and the duration exceeds a preset time. If yes, judging that the N lines are connected into the power grid 30 by mistake, and enabling the three-phase inverter 20 to be in a connection abnormal state so that the three-phase inverter 20 enters a standby state; if not, judging that the N lines are not connected into the power grid 30, and the three-phase inverter 20 is in a normal running state.
The first preset angle range and the second preset angle range are preset intervals, and specifically, a constant is added to the sampling precision and a constant is subtracted from the sampling precision. In this embodiment, the constant is 120 degrees, and taking the sampling precision as 2 degrees as an example, the first preset angle range is 118-122 degrees.
In other embodiments, another controlled module 140 is provided, based on which an inverter N-line detection control circuit is configured as shown in fig. 3, in consideration of the problem that the large size of the relay may cause inconvenient installation, etc. As an example, the output mode of the inverter N-line detection control circuit is three-phase four-wire.
In some embodiments of the present application, the X capacitance in the filter module 110 is connected in a Y-type manner. Specifically, the filtering module 110 includes a capacitor C11, a capacitor C12, and a capacitor C13, where the capacitor C11 is connected between the L1 line and the N line; the capacitor C12 is connected between the L2 line and the N line; a capacitor C13 is connected between the L3 line and the N line. Under the condition that other capacitors are not connected, the capacitance of the capacitor C11, the capacitance of the capacitor C12 and the capacitance of the capacitor C13 are all equal.
In some embodiments of the present application, the control module 130 includes a DSP unit 131 and a relay control unit 132, where an input terminal of the DSP unit 131 is connected to an output terminal of the sampling module 110, an output terminal of the DSP unit 131 is connected to an output terminal of the relay control unit 132, and an output terminal of the relay control unit 132 is connected to the controlled module 140 (i.e., a gate of the MOS transistor Q37 and a gate of the MOS transistor Q38 shown in fig. 3).
In some embodiments of the present application, the controlled module 140 is connected between the L3 line and the N line. The controlled module 140 includes a capacitor C38, a MOS transistor Q37, and a MOS transistor Q38, where a first end of the capacitor C38 is connected to the N line, a second end of the capacitor C38 is connected to a source of the MOS transistor Q38, and a source of the MOS transistor Q37 is connected to the L3 line; the drain of the MOS transistor Q38 and the drain of the MOS transistor Q37 are grounded, and the gate of the MOS transistor Q38 and the gate of the MOS transistor Q37 are connected to the control module 130 (i.e., the output end of the relay control unit 132 shown in fig. 3).
In other embodiments of the present application, the controlled module 140 may be connected between the L1 line or the L2 line and the N line, that is, the first end of the capacitor C38 is connected to the N line, the second end of the capacitor C38 is connected to the source of the MOS transistor Q38, and the source of the MOS transistor Q37 is connected to the L1 line or the L2 line; the drain electrode of the MOS tube Q38 and the drain electrode of the MOS tube Q37 are grounded, and the grid electrode of the MOS tube Q38 and the grid electrode of the MOS tube Q37 are connected to the control module 130.
In the embodiment of the present application, the output mode of the inverter N-line detection control circuit is three-phase four-wire, so the DSP unit 131 needs to send a conducting signal to the relay control unit 132, so that the relay control unit 132 controls the MOS transistor Q37 and the MOS transistor Q38 in the controlled module 140 to be conducted. So that the capacitor C38 is connected between the L3 line and the N line to change the X capacitance of the L3 line to the N line.
Let X capacitance of the capacitor C11, the capacitor C12, and the capacitor C13 be C0, and after the capacitor C38 is connected between the L3 line and the N line, the X capacitance of the L3 line to the N line is C3, c3=c13+c38. It is seen that C3 is greater than C0.
If the output mode of the inverter N-line detection control circuit is three-phase three-line, the DSP unit 131 needs to send a disconnection signal to the relay control unit 132, so that the relay control unit 132 controls the MOS transistor Q37 and the MOS transistor Q38 in the controlled module 140 to be disconnected. The capacitance C38 is not connected between the L3 line and the N line, so the X capacitance of the L3 line to the N line remains unchanged and is still equal to the X capacitance of the L1 line or the L2 line to the N line.
Note that, if the three-phase inverter 20 defaults to the three-phase four-wire output mode, and is not required to be changed to the three-phase three-wire mode, the relay 141 or the MOS transistor Q37 and the MOS transistor Q38 in the controlled module 140 may be removed, so that the capacitor C38 is directly connected between the N line and the L1 line, the L2 line or the L3 line; or the X capacitance capacity of the L3 line to the N line is directly increased, so that the X capacitance capacity of the L3 line to the N line is larger than the X capacitance capacity of the L1 line or the L2 line to the N line.
According to the embodiment of the invention, the capacitance capacity of any one of three lines of the inverter to the N line is controlled and changed, and the N line is detected, so that the inverter can acquire the information of abnormal connection of the N line and protect the inverter under the condition that the set output mode is different from the actual line system, and the safety and the reliability of the inverter are improved.
Based on the inverter N-line detection control circuit provided by the foregoing embodiment, the embodiment of the present application further provides an inverter N-line detection control method, and a flow chart of the method is shown in fig. 5. The method specifically comprises the following steps:
step S100: the control module judges that the preset output mode is a three-phase four-wire mode or a three-phase three-wire mode.
Specifically, the control module determines that the preset output mode of the three-phase inverter is a three-phase four-wire module or a three-phase three-wire mode, and if the output mode is the three-phase four-wire mode, step S200 is executed; if the output mode is the three-phase three-wire mode, step S300 is performed.
Step S200: the control module controls the controlled module to be conducted, and judges whether the N line is not connected to the power grid or not by comparing the first phase angle difference value with a first preset angle range.
In some embodiments of the present application, step S200 specifically includes the following steps:
step S210: the first phase angle difference is calculated from the X capacitance.
Specifically, if the controlled module is connected to the L3 line, the first phase angle difference is calculated by the control module according to the following formula:
，
wherein C3 is the sum of the capacitance C13 and the capacitance X of the controlled module, and C0 is the capacitance C11, C12 or C13.
If the controlled module is connected to the L1 line, the first phase angle difference is calculated by the control module according to the following equation:
，
wherein C1 is the sum of the capacitance C11 and the X capacitance of the controlled module.
If the controlled module is connected to the L2 line, the first phase angle difference is calculated by the control module according to the following equation:
，
wherein C2 is the sum of the capacitance C12 and the X capacitance of the controlled module.
Step S220: judging whether the first phase angle difference exceeds a first preset angle range and the duration exceeds a preset first time.
Specifically, it is determined whether the first phase angle difference exceeds a first preset angle range and the duration exceeds a preset first time, if yes, step S231 is executed; if not, step S231 is performed.
Step S231: and determining that the first phase angle difference is abnormal, wherein the N lines are not connected into the power grid.
After the first phase angle difference is determined to be abnormal, the N lines are considered to be not connected to the power grid, so that the inverter can send alarm information to prompt that the N lines are not connected.
Step S240: the three-phase inverter is put into a standby state.
Step S232: and determining that the first phase angle difference is not abnormal, and accessing N lines into a power grid.
Step S300: the control module controls the controlled module to be disconnected, and judges whether the N line is connected into the power grid by mistake by comparing the second phase angle difference value with a second preset angle range.
In some embodiments of the present application, step S300 specifically includes the following steps:
step S210: the second phase angle difference is calculated from the X capacitance capacity.
Step S220: and judging whether the second phase angle difference exceeds a second preset angle range and the duration exceeds a preset second time.
Step S231: and determining that the second phase angle difference is abnormal, and accessing the N lines into the power grid by mistake.
After the second phase angle difference is determined to be abnormal, the N lines are considered to be connected into the power grid in a wrong way, so that the inverter can send out alarm information to prompt that the output mode is inconsistent with the actual line system, and the N lines are connected into the power grid in a wrong way.
Step S240: the three-phase inverter is put into a standby state.
Step S232: and determining that the second phase angle difference is not abnormal, wherein the N lines are not connected into the power grid.
According to the embodiment of the invention, the capacitance capacity of any one of three lines of the inverter to the N line is controlled and changed, and the N line is detected, so that the inverter can acquire the information of abnormal connection of the N line and protect the inverter under the condition that the set output mode is different from the actual line system, and the safety and the reliability of the inverter are improved.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and are not limiting thereof; the technical features of the above embodiments or in the different embodiments may also be combined under the idea of the present application, the steps may be implemented in any order, and there are many other variations of the different aspects of the present application as above, which are not provided in details for the sake of brevity; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.
Claims (9)
1. An inverter N-line detection control circuit applied to an energy storage system comprising a three-phase inverter, characterized in that the circuit comprises:
the sampling module is used for collecting three-phase voltages of the three-phase inverter;
the filtering module is connected among the L1 line, the L2 line, the L3 line and the N line of the three-phase inverter and used for filtering electromagnetic interference;
the controlled module is connected among any one of the L1 line, the L2 line and the L3 line and the N line, and when the controlled module is conducted, the X capacitance capacity of the line connected with the controlled module to the N line is larger than that of the other two lines to the N line;
the control module is configured to control the controlled module to be switched on or off according to the output mode of the three-phase inverter, if the output mode of the three-phase inverter is a three-phase four-wire mode, the control module controls the controlled module to be switched on, and judges whether the N wire is not connected to a power grid or not by comparing the phase angle difference value of the three-phase voltage with a first preset angle range;
if the output mode is a three-phase three-wire mode, the control module controls the controlled module to be disconnected, and judges whether the N wire is connected into the power grid by mistake by comparing the phase angle difference value of the three-phase voltage with a second preset angle range.
2. The circuit of claim 1, wherein the filter module comprises a capacitor C11, a capacitor C12, and a capacitor C13, wherein,
the capacitor C11 is connected between the L1 line and the N line;
the capacitor C12 is connected between the L2 line and the N line;
the capacitor C13 is connected between the L3 line and the N line.
3. The circuit of claim 1, wherein the controlled module comprises a capacitor C38 and a relay, wherein,
the first end of the capacitor C38 is connected to the N line, the second end of the capacitor C38 is connected to the first end of the relay, the second end of the relay is connected to the L1 line, the L2 line or the L3 line, and the controlled end of the relay is connected to the control module.
4. The circuit of claim 1, wherein the controlled module comprises a capacitor C38, a MOS transistor Q37, and a MOS transistor Q38, wherein,
the first end of the capacitor C38 is connected to the N line, the second end of the capacitor C38 is connected to the source electrode of the MOS tube Q38, and the source electrode of the MOS tube Q37 is connected to the L1 line, the L2 line or the L3 line;
the drain electrode of the MOS tube Q38 and the drain electrode of the MOS tube Q37 are grounded, and the grid electrode of the MOS tube Q38 and the grid electrode of the MOS tube Q37 are connected to the control module.
5. The circuit of claim 3, wherein the control module comprises a DSP unit and a relay control unit, wherein,
the input end of the DSP unit is connected to the output end of the sampling module, the output end of the DSP unit is connected to the output end of the relay control unit, and the output end of the relay control unit is connected to the controlled module;
the DSP unit sends a switching-on signal or a switching-off signal to the relay control unit, so that the relay control unit correspondingly controls the switching-on or switching-off of the relay.
6. The circuit of claim 2, wherein the circuit further comprises a logic circuit,
if the controlled module is connected to the L1 line, the phase angle difference is calculated by the control module according to the following formula:
，
wherein C1 is the sum of the capacitance C11 and the capacitance X of the controlled module, and C0 is the capacitance C11, C12 or C13;
if the controlled module is connected to the L2 line, the phase angle difference is calculated by the control module according to the following formula:
，
wherein C2 is the sum of capacitance C12 and X capacitance of the controlled module;
if the controlled module is connected to the L3 line, the phase angle difference is calculated by the control module according to the following equation:
，
wherein C3 is the sum of the capacitance C13 and the X capacitance of the controlled module.
7. An inverter N-line detection control method applied to the inverter N-line detection control circuit according to any one of claims 1 to 6, characterized by comprising the steps of:
the control module judges whether a preset output mode is a three-phase four-wire mode or a three-phase three-wire mode;
if the output mode is a three-phase four-wire mode, the control module controls the controlled module to be conducted, and judges whether the N wires are not connected into a power grid or not by comparing the phase angle difference value with a first preset angle range;
if the output mode is a three-phase three-wire mode, the control module controls the controlled module to be disconnected, and judges whether the N wire is connected into the power grid by mistake by comparing the phase angle difference value with a second preset angle range.
8. The method of claim 7, wherein the comparing the phase angle difference with the first predetermined angle range to determine whether the N line is not connected to the grid comprises:
calculating a first phase angle difference according to the capacity of the X capacitor;
judging whether the first phase angle difference exceeds the first preset angle range and the duration exceeds preset first time;
if yes, determining that the first phase angle difference is abnormal, wherein the N lines are not connected to the power grid;
if not, determining that the first phase angle difference is not abnormal, wherein the N lines are connected to the power grid;
and if the N lines are not connected to the power grid, enabling the three-phase inverter to enter a standby state.
9. The method of claim 8, wherein determining whether the N-line is misaccessed into the power grid by comparing the phase angle difference to a second predetermined angular range comprises:
calculating a second phase angle difference according to the X capacitance capacity;
judging whether the second phase angle difference exceeds the second preset angle range and the duration exceeds a preset second time;
if yes, determining that the second phase angle difference is abnormal, and accessing the power grid by mistake through the N lines;
if not, determining that the second phase angle difference is not abnormal, wherein the N line is not connected to the power grid;
and if the N lines are connected into the power grid by mistake, enabling the three-phase inverter to enter a standby state.
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