CN115224683A - Power supply system and control method - Google Patents
Power supply system and control method Download PDFInfo
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- CN115224683A CN115224683A CN202211146457.4A CN202211146457A CN115224683A CN 115224683 A CN115224683 A CN 115224683A CN 202211146457 A CN202211146457 A CN 202211146457A CN 115224683 A CN115224683 A CN 115224683A
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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
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/10—Parallel operation of dc sources
- H02J1/108—Parallel operation of dc sources using diodes blocking reverse current flow
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/20—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for electronic equipment
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
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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
- H02J3/381—Dispersed generators
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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
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
Abstract
The application discloses a power supply system and a control method, wherein the system comprises: a DCAC circuit, a controller and at least two boost circuits; the output ends of the at least two booster circuits are connected in parallel to be connected with a direct current bus; the input end of the DCAC circuit is connected with a direct current bus; the controller is used for controlling the DCAC circuit to work in a reverse rectification mode before the wave is sent to the at least two booster circuits so as to raise the voltage of the direct current bus; obtaining a difference value between the raised direct current bus voltage and the input voltage of each booster circuit, and judging that a main power path of the corresponding booster circuit is not short-circuited when the absolute value of the difference value is greater than a set threshold value; otherwise, the main power path of the corresponding booster circuit is judged to be short-circuited. Before each booster circuit does not work, whether short-circuit fault occurs is judged, and when the short-circuit fault occurs, the short-circuit fault is timely removed, so that the normal work of a power supply system is not influenced. The scheme can judge whether the main power path of the booster circuit is short-circuited or not, and the safety of a power supply system is protected.
Description
Technical Field
The application relates to the technical field of power systems, in particular to a power supply system and a control method.
Background
With the continuous development of photovoltaic power generation, more and more photovoltaic strings are connected to the input end of the DCAC circuit, the general photovoltaic strings are connected with the DCAC circuit through the boosting circuit, and the boosting circuit can boost the voltage of the photovoltaic strings and then output the voltage when the photovoltaic strings need boosting.
Typically, the output terminals of the plurality of boost circuits are connected in parallel to the dc bus, i.e., to the input terminals of the DCAC circuit. The main power path of the booster circuit comprises a diode or a switch tube, wherein the switch tube comprises an anti-parallel diode, and the diode is used for preventing current from reversely flowing. When a diode on a main power path of a boost circuit is short-circuited, the boost circuit starts to work, namely, the boost circuit sends waves to a switching tube of the boost circuit, and because the output ends of a plurality of paths of boost circuits are connected in parallel, a direct-current bus is short-circuited, and a photovoltaic system fails in serious cases.
Disclosure of Invention
In view of this, the present application provides a power supply system and a control method thereof, which can determine whether a short circuit occurs in a main power path of a boost circuit, thereby protecting the safety of the power supply system.
The present application provides a power supply system, comprising: a DCAC circuit, a controller, and at least two boost circuits;
the output ends of the at least two booster circuits are connected in parallel to be connected with a direct current bus;
the input end of the DCAC circuit is connected with a direct current bus;
the controller is used for controlling the DCAC circuit to work in a reverse rectification mode before the wave is sent to the at least two booster circuits so as to raise the voltage of the direct current bus; obtaining a difference value between the raised direct current bus voltage and the input voltage of each booster circuit, and judging that a main power path of the corresponding booster circuit is not short-circuited when the absolute value of the difference value is greater than a set threshold value; otherwise, the main power path of the corresponding booster circuit is judged to be short-circuited.
Preferably, the boosted dc bus voltage is greater than the maximum input voltage of the at least two boost circuits.
Preferably, the Boost circuit is a Boost circuit, and the main power path short circuit is specifically a diode short circuit in the active power path;
the diode and the power inductor are connected in series and then connected between the input end and the output end of the Boost circuit;
or the like, or a combination thereof,
the diode is an anti-parallel diode of a switching tube connected with the power inductor in series;
or the like, or, alternatively,
the diode is connected in parallel between the input end and the output end of the Boost circuit.
Preferably, the input end of each booster circuit is used for connecting the corresponding photovoltaic group string.
The present application provides a power supply system comprising: a DCAC circuit, a controller and at least two boost circuits;
the output ends of the at least two booster circuits are connected in parallel to be connected with a direct current bus;
the input end of the DCAC circuit is connected with a direct current bus;
and the controller is used for obtaining a first difference between the direct current bus voltage and the input voltage of each booster circuit before wave sending is carried out on at least two booster circuits, and judging that a main power path in each booster circuit is not short-circuited when the absolute value of the first difference is greater than a set threshold value.
Preferably, the controller is further configured to, when the absolute value of the first difference is smaller than or equal to a set threshold, control the boost circuit with the main power path not short-circuited to operate to raise the dc bus voltage, obtain a second difference between the raised dc bus voltage and the input voltage of the boost circuit with the absolute value of the first difference being smaller than or equal to the set threshold, and when the absolute value of the second difference is smaller than or equal to the set threshold, determine that the main power path of the boost circuit with the absolute value of the first difference being smaller than or equal to the set threshold is short-circuited.
Preferably, the boosted dc bus voltage is greater than the maximum input voltage of the at least two boost circuits.
Preferably, the Boost circuits are Boost circuits, and the input end of each Boost circuit is used for connecting a corresponding photovoltaic group string;
the main power path short circuit is specifically a diode short circuit in the active power path;
the diode and the power inductor are connected in series and then connected between the input end and the output end of the Boost circuit;
or the like, or a combination thereof,
the diode is an anti-parallel diode of a switching tube connected with the power inductor in series;
or the like, or, alternatively,
the diode is connected in parallel between the input end and the output end of the Boost circuit.
The present application also provides a control method of a power supply system, the power supply system including: the method comprises the following steps: a DCAC circuit, a controller and at least two boost circuits; the output ends of the at least two booster circuits are connected in parallel to be connected with a direct current bus; the input end of the DCAC circuit is connected with a direct current bus;
the control method comprises the following steps:
before at least two booster circuits send waves, the DCAC circuit is controlled to work in a reverse rectification mode to raise the voltage of a direct current bus;
obtaining the difference between the raised direct current bus voltage and the input voltage of each booster circuit;
when the absolute value of the difference is larger than a set threshold, judging that the main power path of the corresponding booster circuit is not short-circuited; otherwise, the main power path of the corresponding booster circuit is judged to be short-circuited.
Preferably, the boosted dc bus voltage is greater than the maximum input voltage of the at least two boost circuits.
The present application also provides a control method of a power supply system, the power supply system including: the method comprises the following steps: a DCAC circuit, a controller, and at least two boost circuits; the output ends of the at least two booster circuits are connected in parallel to be connected with a direct current bus; the input end of the DCAC circuit is connected with a direct current bus;
the control method comprises the following steps:
before wave sending is carried out on at least two booster circuits, a first difference value between the direct current bus voltage and the input voltage of each booster circuit is obtained;
and when the absolute value of the first difference is larger than a set threshold, judging that the main power path in the booster circuit is not short-circuited.
Preferably, the method further comprises the following steps: when the absolute value of the first difference value is smaller than or equal to a set threshold value, raising the voltage of the direct-current bus;
obtaining a second difference value of the input voltage of the booster circuit, wherein the absolute value of the raised direct-current bus voltage and the first difference value is smaller than or equal to a set threshold value;
and when the absolute value of the second difference is smaller than or equal to the set threshold, judging that the main power path of the booster circuit of which the absolute value of the first difference is smaller than or equal to the set threshold is short-circuited.
Therefore, the application has the following beneficial effects:
according to the power supply system, before the booster circuits do not work, the controller raises the direct current bus voltage through the DCAC circuit, so that whether the difference value between the input voltage of each booster circuit and the raised direct current bus voltage is larger than a set threshold value or not is judged, when the difference value is larger than the set threshold value, the main power path is cut off under the reverse voltage, namely, the main power path of the booster circuit is not short-circuited, and when the difference value is smaller than or equal to the set threshold value, the main power path is turned on under the reverse voltage, so that the input voltage and the direct current bus voltage are close to or equal to each other, namely, the main power path of the booster circuit is short-circuited. Because whether short-circuit faults occur or not is judged before each booster circuit does not work, the short-circuit faults are cut off in time when the short-circuit faults occur, and the normal work of a power supply system is not influenced.
Drawings
Fig. 1 is a schematic diagram of a power supply system provided in an embodiment of the present application as a photovoltaic system;
FIG. 2 is a specific circuit diagram of FIG. 1;
fig. 3 is a schematic diagram of a power supply system according to an embodiment of the present application;
FIG. 4 is a schematic diagram of another power system provided by an embodiment of the present application;
fig. 5 is a schematic diagram of another power supply system provided in an embodiment of the present application;
fig. 6 is a schematic view of a photovoltaic system provided in an embodiment of the present application;
fig. 7 is a flowchart of a control method of a power supply system according to an embodiment of the present application;
fig. 8 is a flowchart of a control method of a power supply system according to another embodiment of the present disclosure.
Detailed Description
In order to make those skilled in the art better understand the technical solutions provided by the embodiments of the present application, an application scenario of the technical solutions of the present application is described below with reference to the accompanying drawings.
The embodiment of the application does not specifically limit the application scenario, and for example, the application scenario may be an energy storage system, a photovoltaic system, a new energy power automobile, or the like. For convenience of understanding, the following description is given by taking a photovoltaic system as an example, that is, an input end of each voltage boosting circuit is connected to a corresponding photovoltaic string, and one voltage boosting circuit may be connected to one photovoltaic string or may be connected to a plurality of photovoltaic strings, which is not specifically limited herein.
Referring to fig. 1, the power supply system provided in the embodiment of the present application is a schematic diagram of a photovoltaic system.
The photovoltaic system includes m boost circuits, respectively boost circuit 101 and boost circuit 10m. m is an integer of 2 or more. Here, the input voltage of the booster circuit 101 is Vi1, and the input voltage of the booster circuit 10m is Vim. The output end of the voltage boost circuit 101 and the output end of the voltage boost circuit 10m are connected to the input end of the DCAC circuit 200, that is, both are connected to a dc bus, wherein the dc bus capacitance is Cbus. The output of the DCAC circuit 200 is used for connection to the grid.
Referring to fig. 2, a specific circuit diagram of fig. 1 is shown.
Fig. 2 illustrates an example of a Boost circuit as the first Boost circuit, where the first Boost circuit includes a power inductor L1, a power transistor Q1 and a diode D1; the second booster circuit comprises a power inductor Lm, a switching tube Qm and a diode Dm, wherein the input end of the first booster circuit is connected with a capacitor C1, and the input end of the mth booster circuit is connected with a capacitor Cm.
For example, if D1 is shorted, when Q1 is turned on, the positive and negative terminals of the dc bus are directly shorted, and a large short-circuit current will flow through D1 and Q1, possibly causing the entire photovoltaic system to fail.
Therefore, before the booster circuit operates, that is, before the wave is emitted to the power tube of the booster circuit, it is first necessary to determine whether the diode is short-circuited or whether the main power path is short-circuited.
In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the drawings are described in detail below.
Referring to fig. 3, the figure is a schematic diagram of a power supply system according to an embodiment of the present application.
The power supply system provided by the embodiment comprises: a DCAC circuit 200, a controller 300, and at least two boost circuits; the output ends of the at least two booster circuits are connected in parallel to be connected with a direct current bus;
it should be understood that the output terminals of a plurality of voltage boosting circuits are connected in parallel, before each voltage boosting circuit works, the direct current bus voltage depends on the path with the highest input voltage of the voltage boosting circuit, for example, due to the difference of actual conditions such as illumination, the voltages of the photovoltaic string may be different, and the input voltages of the voltage boosting circuits are different.
In this embodiment, the example of m Boost circuits is continued, specifically, the example of a Boost circuit is performed, each Boost circuit includes the same device, and the connection relationship is also the same, and the connection relationship of each device is described below.
The first booster circuit comprises a power inductor L1, a diode D1 and a power tube Q1, wherein the first end of the L1 is connected with the positive input end, the second end of the L1 is connected with the anode of the D1, the cathode of the D1 is connected with the positive end of a direct current bus, the anode of the D1 is connected with the negative end of the direct current bus through the Q1, and meanwhile, the negative input end of the first booster circuit is connected with the negative end of the direct current bus. C1 is connected between the positive input end and the negative input end of the first booster circuit.
The mth booster circuit comprises a power inductor Lm, a diode Dm and a power tube Qm, wherein the first end of the Lm is connected with the positive input end, the second end of the Lm is connected with the anode of the Dm, the cathode of the Dm is connected with the positive end of a direct current bus, the anode of the Dm is connected with the negative end of the direct current bus through the Qm, and meanwhile, the negative input end of the mth booster circuit is connected with the negative end of the direct current bus. Cm is connected between the positive input end and the negative input end of the mth booster circuit.
The input end of the DCAC circuit 200 is connected with a direct current bus;
the controller 300 is configured to control the DCAC circuit 200 to operate in the reverse rectification mode to boost the dc bus voltage before the at least two boost circuits generate waves, that is, before the power transistors in the boost circuits act; obtaining the difference between the raised direct-current bus voltage and the input voltage of each booster circuit, and when the absolute value of the difference is greater than a set threshold, indicating that the main power path is cut off under the reverse voltage, namely judging that the main power path of the corresponding booster circuit is not short-circuited; otherwise, the main power path of the corresponding booster circuit is judged to be short-circuited.
For example, if the input voltage of the first boost circuit is the highest one of the m boost circuits, the dc bus voltage depends on the input voltage Vi1.
In order to accurately judge whether the active power paths in each boosting circuit are short-circuited or not, the DCAC circuit 200 can be controlled to work first, because the DCAC circuit 200 can work in two directions, namely forward inversion and reverse rectification, the DCAC circuit 200 is controlled to work in a reverse rectification mode at the moment to raise the direct current bus voltage, and at the moment, the raised direct current bus voltage is greater than the maximum input voltage of at least two boosting circuits, namely higher than the input voltage of any one boosting circuit. If the difference value between the raised direct-current bus voltage and the input voltage of the booster circuit is smaller than or equal to the set threshold value, the main power path is conducted under reverse voltage, so that the input voltage and the direct-current bus voltage are close to or equal, namely the main power path of the booster circuit is short-circuited.
The embodiment of the present application does not specifically limit the specific size of the set threshold, for example, the set threshold may be greater than or equal to the maximum error of the sampling circuit. The technical scheme provided by the embodiment of the application is suitable for judging the short circuit of any device in the main power path of the booster circuit and is not limited to judging the short circuit of the diode. For example, the short circuit determination of D1 to Dm is not limited.
The main power path short circuit is specifically a diode short circuit in the active power path; the diode and the power inductor are connected in series and then connected between the input end and the output end of the Boost circuit.
Or the like, or, alternatively,
the diode is connected in parallel between the input end and the output end of the Boost circuit. Specifically, reference may be made to fig. 4, which is a schematic diagram of another power supply system provided in the embodiment of the present application.
D1 is used as a bypass diode between the input terminal and the output terminal of the voltage boost circuit 101, that is, when D1 is conducted in the forward direction, the input terminal and the output terminal of the voltage boost circuit 101 are short-circuited; when D1 is short-circuited, the input terminal of the booster circuit 101 and the output terminal of the booster circuit 101 are short-circuited together, and the output voltage of the booster circuit 101 is equal to the input voltage. Similarly, dm functions as a bypass diode between the input terminal and the output terminal of the booster circuit 10m.
Or the like, or a combination thereof,
the diode is an anti-parallel diode of a switching tube connected with the power inductor in series. Referring to fig. 5, a schematic diagram of another power supply system provided in the embodiment of the present application is shown.
The difference between fig. 5 and fig. 3 is that the diode is replaced by a switch tube, but the switch tube includes an anti-parallel diode, i.e., D1 in the first boost circuit is the anti-parallel diode of the switch tube, and Dm in the mth boost circuit is the anti-parallel diode of the switch tube.
The technical scheme can also judge whether the short circuit occurs between D1 and Dm.
When the controller judges that the diode in the booster circuit is short-circuited, the short-circuit alarm can be given out in time, in addition, the short-circuited booster circuit can be cut off, and the normal booster circuit can continue to work normally.
The power supply system provided by the embodiment of the application can be a photovoltaic system, and is described in detail below with reference to the accompanying drawings.
Referring to fig. 6, the figure is a schematic view of a photovoltaic system provided in an embodiment of the present application.
The input end of each booster circuit is used for connecting the corresponding photovoltaic group string. That is, the input terminal of the booster circuit 101 is connected to the PV string PV1, and the input terminal of the booster circuit 10m is connected to the PV string PVm. Namely, the energy at the input end of the booster circuit is derived from the photovoltaic string.
The number of the specific photovoltaic strings is not limited by PV1 and PVm, and is only illustrated.
When one or more of the boosting circuits are short-circuited, the boosting circuit with the short-circuit fault and the corresponding photovoltaic string can be cut off from the photovoltaic system, and other photovoltaic strings and the boosting circuits can continue to work normally without influencing the normal operation of the photovoltaic system.
The technical scheme introduced in the above embodiment is that the controller controls the subsequent DCAC circuit to operate first to raise the dc bus voltage, and the following describes an implementation manner in which the subsequent DCAC circuit does not operate and determines whether a short circuit exists in each voltage boosting circuit.
The power supply system provided by the embodiment comprises: a DCAC circuit, a controller and at least two boost circuits;
the output ends of the at least two booster circuits are connected in parallel to be connected with a direct current bus;
the input end of the DCAC circuit is connected with a direct current bus;
and the controller is used for obtaining a first difference between the direct-current bus voltage and the input voltage of each booster circuit before wave sending is carried out on at least two booster circuits, and judging that a main power path in each booster circuit is not short-circuited when the absolute value of the first difference is larger than a set threshold value.
The specific size of the set threshold is not particularly limited in this embodiment, and for example, the set threshold may be greater than or equal to the conduction voltage drop of the diode and the maximum error of the sampling circuit.
Because each booster circuit does not start to convert the electric energy, namely does not send a driving signal to the power tube, the power tube is in a turn-off state, and even if a main power path of the booster circuit has a short circuit, serious accidents can not be caused.
When each booster circuit is normal, the voltage difference between the dc bus voltage and the booster circuit input voltage is due to the reverse blocking characteristic of the diode, and therefore, the voltage difference is used to determine whether the booster circuit has a short-circuit fault. If the voltage difference is too small, it indicates that the main power path is conducting under reverse voltage, resulting in the input voltage and the dc bus voltage being close to or equal, i.e. there is a short circuit of the diode on the main power path of the boost circuit.
The power supply system provided by the embodiment of the application carries out short circuit judgment on each booster circuit before each booster circuit works, and when a short circuit occurs, measures are taken in time, so that serious accidents such as direct current bus short circuit caused by the short circuit are avoided, and the whole power supply system is possibly disabled in serious conditions.
In order to more accurately determine whether the short circuit occurs in the boost circuit, the boost circuit that has been determined not to have a short circuit may be operated to raise the dc bus voltage. As described in detail below.
The controller is further used for controlling the boosting circuit which is not short-circuited in the main power path to work to boost the direct current bus voltage when the absolute value of the first difference is smaller than or equal to a set threshold value, so as to obtain a second difference between the boosted direct current bus voltage and the input voltage of the boosting circuit of which the absolute value of the first difference is smaller than or equal to the set threshold value, namely obtain a second difference between the boosted direct current bus voltage and the input voltage of the boosting circuit to be judged;
and when the absolute value of the second difference is smaller than or equal to the set threshold, judging that the main power path of the booster circuit of which the absolute value of the first difference is smaller than or equal to the set threshold is short-circuited, namely judging that the main power path of the booster circuit to be judged is short-circuited.
The raised direct current bus voltage is greater than the maximum input voltage of at least two booster circuits, namely greater than the maximum input voltage of all booster circuits.
Taking the application of a power supply system in the field of photovoltaic power generation as an example, the booster circuits are Boost circuits, and the input end of each booster circuit is used for connecting a corresponding photovoltaic group string;
the situation of short circuit of the main power path of the booster circuit can comprise the following conditions:
the main power path short circuit is specifically a diode short circuit in the active power path;
the diode and the power inductor are connected in series and then connected between the input end and the output end of the Boost circuit;
or the like, or a combination thereof,
the diode is an anti-parallel diode of a switching tube connected with the power inductor in series;
or the like, or, alternatively,
the diode is connected in parallel between the input end and the output end of the Boost circuit.
The power supply system provided by the embodiment of the application can judge whether a short-circuit fault exists before each booster circuit is started to work, so that measures are taken for the failed booster circuit in time, and more serious accidents are avoided.
Based on the power supply system provided by the above embodiments, the embodiments of the present application further provide a control method of the power supply system, which is described in detail below with reference to the accompanying drawings.
Referring to fig. 7, this figure is a flowchart of a control method of a power supply system according to an embodiment of the present application.
The control method of the power supply system provided by the embodiment, wherein the power supply system includes: the method comprises the following steps: a DCAC circuit, a controller and at least two boost circuits; the output ends of the at least two booster circuits are connected in parallel to be connected with a direct current bus; the input end of the DCAC circuit is connected with a direct current bus;
the control method comprises the following steps:
s701: before at least two booster circuits send waves, the DCAC circuit is controlled to work in a reverse rectification mode to raise the voltage of a direct current bus;
in this embodiment, because all boost circuits do not work yet, consequently, control the direct current bus voltage through the DCAC circuit of back-stage and raise, and then can more accurately judge whether each boost circuit has short-circuit fault.
S702: obtaining the difference between the raised direct current bus voltage and the input voltage of each booster circuit;
because each booster circuit is not operated and the reverse blocking characteristic of the diode is adopted, when the diode is normal, the direct current bus voltage is greater than the input voltage, and therefore, a voltage difference exists between the two.
S703: when the absolute value of the difference is larger than a set threshold, judging that the main power path of the corresponding booster circuit is not short-circuited; otherwise, the main power path of the corresponding booster circuit is judged to be short-circuited.
If the difference value is larger than the set threshold value, it is indicated that the input voltage of the booster circuit is not equal to the raised direct-current bus voltage, namely, the diode is not short-circuited.
The raised direct current bus voltage is greater than the maximum input voltage of the at least two booster circuits.
It should be understood that, in the embodiment of the present application, the input voltage is compared with the dc bus voltage, and the input voltage of each of the boosting circuits is independently compared with the dc bus voltage, and whether a short-circuit fault exists in a corresponding one of the boosting circuits is determined according to the difference.
According to the control method provided by the embodiment of the application, before the boost circuits do not work, the DC bus voltage is raised through the DCAC circuit, so that whether the difference value between the input voltage of each boost circuit and the raised DC bus voltage is larger than a set threshold value or not is judged, when the difference value is larger than the set threshold value, the main power path is cut off under the reverse voltage, namely the main power path of the boost circuit is not short-circuited, and when the difference value is smaller than or equal to the set threshold value, the main power path is turned on under the reverse voltage, so that the input voltage and the DC bus voltage are close to or equal to each other, namely the main power path of the boost circuit is short-circuited. Because whether short-circuit faults occur or not is judged before each booster circuit does not work, the short-circuit faults are cut off in time when the short-circuit faults occur, and the normal work of a power supply system is not influenced.
The embodiment of the present application further provides a control method of a power supply system, which is described in detail below with reference to the accompanying drawings.
Referring to fig. 8, a flowchart of a control method of a power supply system according to another embodiment of the present application is provided.
The present embodiment provides a method for controlling a power supply system, where the power supply system includes: the method comprises the following steps: a DCAC circuit, a controller, and at least two boost circuits; the output ends of the at least two booster circuits are connected in parallel to be connected with a direct current bus; the input end of the DCAC circuit is connected with a direct current bus;
the control method comprises the following steps:
s801: before wave sending is carried out on at least two booster circuits, a first difference value between the direct-current bus voltage and the input voltage of each booster circuit is obtained;
s801: and when the absolute value of the first difference is larger than a set threshold, judging that the main power path in the booster circuit is not short-circuited.
The control method further comprises the following steps:
when the absolute value of the first difference is smaller than or equal to a set threshold, the voltage of the direct-current bus is raised by controlling the operation of a booster circuit of which the main power path is not short-circuited;
obtaining a second difference value of the input voltage of the booster circuit, wherein the absolute value of the raised direct-current bus voltage and the first difference value is smaller than or equal to a set threshold value;
and when the absolute value of the second difference is smaller than or equal to the set threshold, judging that the main power path of the booster circuit of which the absolute value of the first difference is smaller than or equal to the set threshold is short-circuited.
In this embodiment, in order to avoid misjudgment, whether the voltage boost circuit is short-circuited or not is accurately judged, and then the voltage boost circuit which is not short-circuited and has judged the result is controlled to work to raise the voltage of the direct current bus, so that the difference between the voltage of the direct current bus and the input voltage is larger, and the circuit sampling identification is easier.
It should be noted that, in the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments may be referred to each other. For the system or the device disclosed by the embodiment, the description is simple because the system or the device corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (12)
1. A power supply system, comprising: a DCAC circuit, a controller, and at least two boost circuits;
the output ends of the at least two booster circuits are connected in parallel to be connected with a direct current bus;
the input end of the DCAC circuit is connected with the direct current bus;
the controller is used for controlling the DCAC circuit to work in a reverse rectification mode before the wave is sent to the at least two booster circuits so as to raise the voltage of the direct current bus; obtaining a difference value between the raised direct current bus voltage and the input voltage of each booster circuit, and judging that a main power path of the corresponding booster circuit is not short-circuited when the absolute value of the difference value is greater than a set threshold value; and otherwise, judging that the main power path of the corresponding booster circuit is short-circuited.
2. The power system of claim 1, wherein the elevated dc bus voltage is greater than a maximum input voltage of the at least two boost circuits.
3. The power supply system according to claim 1 or 2, wherein the Boost circuit is a Boost circuit, and the main power path short circuit is in particular a diode short circuit in the active power path;
the diode and the power inductor are connected in series and then connected between the input end and the output end of the Boost circuit;
or the like, or a combination thereof,
the diode is an anti-parallel diode of a switching tube connected with the power inductor in series;
or the like, or a combination thereof,
the diode is connected in parallel between the input end and the output end of the Boost circuit.
4. The power system of claim 3, wherein the input of each of the boost circuits is configured to connect to a corresponding string of photovoltaic strings.
5. A power supply system, comprising: a DCAC circuit, a controller and at least two boost circuits;
the output ends of the at least two booster circuits are connected in parallel to be connected with a direct current bus;
the input end of the DCAC circuit is connected with the direct current bus;
the controller is used for obtaining a first difference between the direct current bus voltage and the input voltage of each booster circuit before wave sending is carried out on the at least two booster circuits, and when the absolute value of the first difference is larger than a set threshold value, it is judged that a main power path in each booster circuit is not short-circuited.
6. The power supply system according to claim 5, wherein the controller is further configured to control the boost circuit whose main power path is not short-circuited to operate to raise the dc bus voltage when an absolute value of the first difference is equal to or smaller than the set threshold, obtain a second difference between the raised dc bus voltage and an input voltage of the boost circuit whose absolute value of the first difference is equal to or smaller than the set threshold, and determine that the main power path of the boost circuit whose absolute value of the first difference is equal to or smaller than the set threshold is short-circuited when an absolute value of the second difference is equal to or smaller than the set threshold.
7. The power system of claim 5 or 6, wherein the elevated DC bus voltage is greater than the largest input voltage of the at least two boost circuits.
8. The power supply system of claim 7, wherein the Boost circuits are Boost circuits, and an input end of each Boost circuit is used for connecting a corresponding photovoltaic group string;
the main power path short circuit is specifically a diode short circuit in the active power path;
the diode and the power inductor are connected in series and then connected between the input end and the output end of the Boost circuit;
or the like, or a combination thereof,
the diode is an anti-parallel diode of a switching tube connected with the power inductor in series;
or the like, or a combination thereof,
the diode is connected in parallel between the input end and the output end of the Boost circuit.
9. A control method of a power supply system, characterized in that the power supply system includes: the method comprises the following steps: a DCAC circuit, a controller, and at least two boost circuits; the output ends of the at least two booster circuits are connected in parallel to be connected with a direct current bus; the input end of the DCAC circuit is connected with the direct current bus;
the control method comprises the following steps:
before the at least two booster circuits send waves, the DCAC circuit is controlled to work in a reverse rectification mode so as to raise the voltage of a direct current bus;
obtaining a difference value between the raised direct current bus voltage and the input voltage of each booster circuit;
when the absolute value of the difference is larger than a set threshold, judging that the main power path of the corresponding booster circuit is not short-circuited; and otherwise, judging that the main power path of the corresponding booster circuit is short-circuited.
10. The control method of claim 9, wherein the elevated dc bus voltage is greater than a maximum input voltage of the at least two boost circuits.
11. A control method of a power supply system, characterized in that the power supply system comprises: the method comprises the following steps: a DCAC circuit, a controller, and at least two boost circuits; the output ends of the at least two booster circuits are connected in parallel to be connected with a direct current bus; the input end of the DCAC circuit is connected with the direct current bus;
the control method comprises the following steps:
before wave sending is carried out on the at least two booster circuits, a first difference value between the direct-current bus voltage and the input voltage of each booster circuit is obtained;
and when the absolute value of the first difference is larger than a set threshold, judging that a main power path in the booster circuit is not short-circuited.
12. The control method according to claim 11, characterized by further comprising:
when the absolute value of the first difference value is smaller than or equal to the set threshold value, raising the voltage of the direct-current bus;
obtaining a second difference value of the input voltage of the booster circuit, wherein the absolute value of the raised direct-current bus voltage and the first difference value is smaller than or equal to the set threshold value;
and when the absolute value of the second difference is smaller than or equal to the set threshold, judging that the main power path of the booster circuit of which the absolute value of the first difference is smaller than or equal to the set threshold is short-circuited.
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| CN202211146457.4A CN115224683A (en) | 2022-09-20 | 2022-09-20 | Power supply system and control method |
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| CN102804574A (en) * | 2009-06-18 | 2012-11-28 | 丰田自动车株式会社 | Converter output diode shortcircuit detection device |
| CN103973149A (en) * | 2013-01-24 | 2014-08-06 | 欧姆龙株式会社 | Power conditioner, photovoltaic system and abnormality determination method |
| CN110888085A (en) * | 2019-11-29 | 2020-03-17 | 华为数字技术（苏州）有限公司 | Inverter short circuit detection method and device and inverter |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102804574A (en) * | 2009-06-18 | 2012-11-28 | 丰田自动车株式会社 | Converter output diode shortcircuit detection device |
| CN103973149A (en) * | 2013-01-24 | 2014-08-06 | 欧姆龙株式会社 | Power conditioner, photovoltaic system and abnormality determination method |
| CN110888085A (en) * | 2019-11-29 | 2020-03-17 | 华为数字技术（苏州）有限公司 | Inverter short circuit detection method and device and inverter |
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