CN111917124B - Control device and method for solar photovoltaic grid-connected inverter - Google Patents
Control device and method for solar photovoltaic grid-connected inverter Download PDFInfo
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- CN111917124B CN111917124B CN201910375695.4A CN201910375695A CN111917124B CN 111917124 B CN111917124 B CN 111917124B CN 201910375695 A CN201910375695 A CN 201910375695A CN 111917124 B CN111917124 B CN 111917124B
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Abstract
The application discloses solar photovoltaic grid-connected inverter's controlling means, this controlling means includes: the bus current detection module is used for detecting the bus current of a direct current bus of the target solar photovoltaic grid-connected inverter; and the hiccup control module is used for controlling the output current of the target solar photovoltaic grid-connected inverter by using the hiccup mode when the bus current is less than or equal to the preset current value. Therefore, when the bus current is smaller than or equal to the preset current value, the output current of the target solar photovoltaic grid-connected inverter can be accumulated by utilizing a hiccup mode, so that harmonic waves and burrs generated by the output current of the target solar photovoltaic grid-connected inverter can be avoided, and the quality of the output alternating current of the target solar photovoltaic grid-connected inverter can be relatively improved. Correspondingly, the control method of the solar photovoltaic grid-connected inverter disclosed by the application also has the beneficial effects.
Description
Technical Field
The invention relates to the technical field of inverters, in particular to a control device and a control method of a solar photovoltaic grid-connected inverter.
Background
The solar photovoltaic grid-connected inverter is widely applied in the world due to energy conservation and environmental protection, but the output current of the solar photovoltaic grid-connected inverter is usually mismatched with the current of a power grid, and at the moment, in order to ensure that the current of the solar photovoltaic grid-connected inverter can effectively enter the power grid, the Total Harmonic Distortion (THD) of the solar photovoltaic grid-connected inverter is usually required to be less than 5%. However, due to the characteristic of switch control of the solar photovoltaic grid-connected inverter, when the power of the solar photovoltaic grid-connected inverter is very low, the THD is higher than 5%, so that the solar photovoltaic grid-connected inverter can output alternating current with poor quality. At present, no effective solution is available for the technical problem.
Therefore, how to improve the quality of the alternating current output by the solar photovoltaic grid-connected inverter is a problem to be solved urgently by the technical staff in the field.
Disclosure of Invention
In view of this, the present invention provides a control apparatus and method for a solar photovoltaic grid-connected inverter, so as to improve the quality of the ac output of the solar photovoltaic grid-connected inverter. The specific scheme is as follows:
a control device of a solar photovoltaic grid-connected inverter comprises:
the bus current detection module is used for detecting the bus current of a direct current bus of the target solar photovoltaic grid-connected inverter;
and the hiccup control module is used for controlling the output current of the target solar photovoltaic grid-connected inverter by using a hiccup mode when the bus current is less than or equal to a preset current value.
Preferably, the hiccup control module comprises:
the bus voltage detection unit is used for detecting the bus voltage of a direct current bus of the target solar photovoltaic grid-connected inverter;
the hiccup control unit is used for generating a target hiccup control signal according to the bus current and the bus voltage when the bus current is smaller than or equal to a preset current value;
the alternating voltage and current detection unit is used for acquiring the voltage and the current of the output end of the target solar photovoltaic grid-connected inverter;
the reference unit is used for generating reference current of each phase according to the voltage and current of the output end of the target solar photovoltaic grid-connected inverter, the bus voltage and the target hiccup control signal;
the inductive current sampling unit is used for collecting each phase of inductive current of the target solar photovoltaic grid-connected inverter;
the lower bridge arm voltage detection unit is used for detecting the drain-source voltage of each phase of lower bridge arm switching tube in the target solar photovoltaic grid-connected inverter;
the driving unit is used for turning off a corresponding phase switching tube when the inductive current of each phase is increased to a corresponding phase reference current, and turning on the corresponding phase switching tube when the drain-source voltage of the bridge arm switching tube under each phase is reduced to a preset voltage so as to control the output current of the target solar photovoltaic grid-connected inverter by utilizing the hiccup mode; and the preset voltage is the drain-source voltage when the inductive current of each phase is zero.
Correspondingly, the invention also discloses a control method of the solar photovoltaic grid-connected inverter, which comprises the following steps:
detecting the bus current of a direct current bus of a target solar photovoltaic grid-connected inverter;
and when the bus current is less than or equal to a preset current value, controlling the output current of the target solar photovoltaic grid-connected inverter by utilizing a hiccup mode.
Preferably, when the bus current is less than or equal to a preset current value, the process of controlling the output current of the target solar photovoltaic grid-connected inverter by using a hiccup mode includes:
detecting the bus voltage of a direct current bus of the target solar photovoltaic grid-connected inverter;
when the bus current is smaller than or equal to a preset current value, generating a target hiccup control signal according to the bus current and the bus voltage;
acquiring the voltage and the current of the output end of the target solar photovoltaic grid-connected inverter;
generating reference current of each phase according to the voltage and current of the output end of the target solar photovoltaic grid-connected inverter, the bus voltage and the target hiccup control signal;
collecting each phase of inductive current of the target solar photovoltaic grid-connected inverter;
detecting drain-source voltage of each phase lower bridge arm switching tube in the target solar photovoltaic grid-connected inverter;
when the inductance current of each phase is increased to the reference current of the corresponding phase, the corresponding phase switching tube is turned off, and when the drain-source voltage of the bridge arm switching tube under each phase is reduced to a preset voltage, the corresponding phase switching tube is turned on so as to control the output current of the target solar photovoltaic grid-connected inverter by utilizing the hiccup mode; and the preset voltage is the drain-source voltage when the inductive current of each phase is zero.
Preferably, the process of generating each phase of reference current according to the voltage and current at the output end of the target solar photovoltaic grid-connected inverter, the bus voltage and the target hiccup control signal includes:
and starting to generate reference current of each phase according to the voltage and the current of the output end of the target solar photovoltaic grid-connected inverter, and stopping generating the reference current of each phase according to the bus voltage or the bus current.
Preferably, the step of stopping generating the reference current for each phase according to the bus voltage or the bus current includes:
and based on a preset proportional function, stopping generating the reference current of each phase according to the bus current.
Preferably, the step of stopping generating the reference current for each phase according to the bus voltage or the bus current includes:
and if the bus voltage is smaller than a preset voltage value, stopping generating the reference current of each phase.
Preferably, the process of generating the reference currents of the phases according to the voltage and the current of the output end of the target solar photovoltaic grid-connected inverter, the bus voltage and the target hiccup control signal includes:
if the bus voltage is greater than or equal to the upper limit of a preset voltage range, starting to generate the reference current of each phase;
and if the bus voltage is smaller than the lower limit of the preset voltage range, stopping generating the reference current of each phase.
Therefore, in the invention, firstly, the bus current of the direct current bus of the target solar photovoltaic grid-connected inverter is detected, then, when the bus current is less than or equal to the preset current value, the hiccup mode is used for controlling the output current of the target solar photovoltaic grid-connected inverter, namely, when the bus current is less than or equal to the preset current value, the hiccup gap of the hiccup mode is used for carrying out energy accumulation on the output current of the target solar photovoltaic grid-connected inverter, so that harmonic waves and burrs generated in the output current of the target solar photovoltaic grid-connected inverter can be avoided, and the quality of the output alternating current of the target solar photovoltaic grid-connected inverter can be relatively improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a structural diagram of a control device of a solar photovoltaic grid-connected inverter according to an embodiment of the present invention;
fig. 2 is a structural diagram of a target solar photovoltaic grid-connected inverter provided in an embodiment of the present invention;
fig. 3 is a logic diagram of a control device of a solar photovoltaic grid-connected inverter for controlling the output current of a target solar photovoltaic grid-connected inverter in the prior art;
fig. 4 is a logic schematic diagram of the control device of the solar photovoltaic grid-connected inverter according to the embodiment of the present invention controlling the output current of the target solar photovoltaic grid-connected inverter;
fig. 5 is a structural diagram of another control device of a solar photovoltaic grid-connected inverter according to an embodiment of the present invention;
fig. 6 is a structural diagram of controlling an output current of a target solar photovoltaic grid-connected inverter by using a normal operation mode according to an embodiment of the present invention;
fig. 7 is a schematic diagram of an output curve of a target solar photovoltaic grid-connected inverter in a normal operating mode and waveforms of driving signals;
fig. 8 is a schematic diagram of the output current, the reference current and the switching tube driving signal of the target solar photovoltaic grid-connected inverter in the normal operation mode;
fig. 9 is a flowchart of a control method of a solar photovoltaic grid-connected inverter according to an embodiment of the present invention;
fig. 10 is a schematic diagram of a grid voltage, a reference current and an output current of a target solar photovoltaic grid-connected inverter in a hiccup mode.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, fig. 1 is a structural diagram of a control device of a solar photovoltaic grid-connected inverter according to an embodiment of the present invention, where the control device includes:
the bus current detection module 11 is used for detecting the bus current of a direct current bus of the target solar photovoltaic grid-connected inverter;
and the hiccup control module 12 is used for controlling the output current of the target solar photovoltaic grid-connected inverter by using a hiccup mode when the bus current is less than or equal to a preset current value.
In the embodiment, in order to enable the target solar photovoltaic grid-connected inverter to output the alternating current with high quality. Firstly, a bus current detection module 11 for detecting the bus current of a direct current bus of a target solar photovoltaic grid-connected inverter is arranged in a control device of the solar photovoltaic grid-connected inverter, and then a hiccup control module 12 for controlling the output current of the target solar photovoltaic grid-connected inverter by using a hiccup mode is arranged in the control device of the solar photovoltaic grid-connected inverter when the bus current of the direct current bus is less than or equal to a preset current value. That is, when the bus current of the dc bus is less than or equal to the preset current value, the hiccup control module 12 intermittently controls the output current of the target solar photovoltaic grid-connected inverter, so that the energy of the output current of the target solar photovoltaic grid-connected inverter can be accumulated in the hiccup gap, and the quality of the output current of the target solar photovoltaic grid-connected inverter can be improved.
Here, a description is given by way of a specific example. Referring to fig. 2, fig. 2 is a structural diagram of a target solar photovoltaic grid-connected inverter, which is composed of a dc boost module, a dc bus and a high-frequency inverter module. The direct current boosting module is described by taking a flyback circuit as an example, and the flyback circuit mainly comprises a primary side switching tube Sm, a transformer T and a flyback diode D; the dc bus includes a capacitor Cm, and the high-frequency inverter module is specifically described by taking a full-bridge circuit as an example.
Referring to fig. 3, fig. 3 is a logic diagram illustrating that a control device of a solar photovoltaic grid-connected inverter controls an output current of a target solar photovoltaic grid-connected inverter in the prior art. The input end of the target solar photovoltaic grid-connected inverter is connected with the PV component, the output end of the target solar photovoltaic grid-connected inverter is connected with an alternating current power grid, the input current-voltage detection module is used for detecting the voltage and the current of the input end of the target solar photovoltaic grid-connected inverter and sending the detected voltage and the detected current of the input end of the target solar photovoltaic grid-connected inverter to the MPPT control module, and when the MPPT control module obtains the voltage and the current of the input end of the target solar photovoltaic grid-connected inverter, a corresponding control signal can be sent to a primary side switch tube Sm in the direct current boosting module, so that the PV component can work at a maximum power point, and the direct current boosting module can complete a boosting process. Meanwhile, the bus voltage detection module can detect the bus voltage of the direct-current bus in real time and send the bus voltage of the direct-current bus to the inversion switch control module in the target solar photovoltaic grid-connected inverter, and at the moment, the inversion switch control module can send corresponding control signals to the high-frequency inversion module according to the bus voltage of the direct-current bus and the voltage and current of the alternating-current power grid detected by the alternating-current voltage and current detection module, so that the high-frequency inversion module in the target solar photovoltaic grid-connected inverter can generate required alternating current. However, the quality of the output current of the target solar photovoltaic grid-connected inverter is poor due to the control mode of the target solar photovoltaic grid-connected inverter.
Referring to fig. 4, fig. 4 is a logic schematic diagram of the control device of the solar photovoltaic grid-connected inverter according to the embodiment of the present invention controlling the output current of the target solar photovoltaic grid-connected inverter. Compared with the prior art, bus current detection module and hiccup mode control module have been increased to, when bus current detection module 11 detected direct current bus's bus current and is less than preset current value, hiccup control module 12 will control target solar photovoltaic grid-connected inverter's output current with hiccup mode.
It can be understood that when the bus current of the direct current bus is less than or equal to the preset current value, the output current of the target solar photovoltaic grid-connected inverter is controlled in the hiccup mode, so that the control device of the solar photovoltaic grid-connected inverter can utilize the hiccup gap in the hiccup mode to accumulate the energy of the output current of the target solar photovoltaic grid-connected inverter when the bus current of the direct current bus of the target solar photovoltaic grid-connected inverter is less than or equal to the preset current value, thus relatively avoiding the harmonic waves and burrs generated by the output current of the target solar photovoltaic grid-connected inverter, and relatively improving the quality of the output current of the target solar photovoltaic grid-connected inverter.
In addition, if the bus current of the direct current bus of the target solar photovoltaic grid-connected inverter is greater than the preset current value, the output current of the target solar photovoltaic grid-connected inverter can be stopped being controlled by the hiccup mode, so that the energy conversion efficiency of the target solar photovoltaic grid-connected inverter can be relatively improved.
It can be seen that, in this embodiment, firstly, the bus current of the dc bus of the target solar photovoltaic grid-connected inverter is detected, then, when the bus current is less than or equal to the preset current value, the hiccup mode is used to control the output current of the target solar photovoltaic grid-connected inverter, that is, when the bus current is less than or equal to the preset current value, the hiccup gap of the hiccup mode is used to perform energy accumulation on the output current of the target solar photovoltaic grid-connected inverter, so that the harmonic waves and burrs occurring in the output current of the target solar photovoltaic grid-connected inverter can be avoided, and thus the quality of the output ac current of the target solar photovoltaic grid-connected inverter can be relatively improved.
Based on the above embodiments, the present embodiment further describes and optimizes the technical solution, please refer to fig. 5, and fig. 5 is a structural diagram of another control device of a solar photovoltaic grid-connected inverter according to an embodiment of the present invention. Specifically, the hiccup control module 12 includes:
a bus voltage detection unit 121, configured to detect a bus voltage of a dc bus of the target solar photovoltaic grid-connected inverter;
the hiccup control unit 122 is used for generating a target hiccup control signal according to the bus current and the bus voltage when the bus current is less than or equal to a preset current value;
the alternating voltage and current detection module 123 is configured to obtain a voltage and a current at an output end of the target solar photovoltaic grid-connected inverter;
the reference unit 124 is used for generating reference current of each phase according to the voltage and current of the output end of the target solar photovoltaic grid-connected inverter, the bus voltage and the target hiccup control signal;
the inductive current sampling unit 125 is used for collecting each phase inductive current of the target solar photovoltaic grid-connected inverter;
the lower bridge arm voltage detection unit 126 is used for detecting the drain-source voltage of each phase of lower bridge arm switching tube in the target solar photovoltaic grid-connected inverter;
the driving unit 127 is used for turning off the corresponding phase switching tube when the inductive current of each phase is increased to the corresponding phase reference current, and turning on the corresponding phase switching tube when the drain-source voltage of the bridge arm switching tube under each phase is reduced to a preset voltage so as to control the output current of the target solar photovoltaic grid-connected inverter by utilizing a hiccup mode;
the preset voltage is the drain-source voltage when the inductive current of each phase is zero.
In the present embodiment, the specific working principle of the hiccup control module 12 is explained in detail. Referring to fig. 5, in fig. 5, a bus current detection module 11 is configured to detect a bus current of a dc bus of a target solar photovoltaic grid-connected inverter, a bus voltage detection unit 121 is configured to detect a bus voltage of the dc bus of the target solar photovoltaic grid-connected inverter, an ac voltage and current detection unit 123 is configured to obtain a voltage and a current at an output end of the target solar photovoltaic grid-connected inverter, an inductive current sampling unit 125 is configured to collect an inductive current of each phase of the target solar photovoltaic grid-connected inverter, and a lower bridge arm voltage detection unit 126 is configured to detect a drain-source voltage of a lower bridge arm switch tube of each phase in the target solar photovoltaic grid-connected inverter.
The hiccup control unit 122 has an input end connected to the bus current detection module 11 and the bus voltage detection unit 121, and is configured to generate a target hiccup control signal according to a bus current and a bus voltage of a dc bus of a target solar photovoltaic grid-connected inverter when the bus current of the dc bus of the target solar photovoltaic grid-connected inverter is less than or equal to a preset current value; the input end of the reference unit 124 is connected to the output end of the hiccup control unit 122, the output end of the bus voltage detection unit 121, and the output end of the alternating voltage and current detection unit 123, respectively, and is configured to generate each phase of reference current according to the voltage and current at the output end of the target solar photovoltaic grid-connected inverter, the bus voltage of the direct current bus in the target solar photovoltaic grid-connected inverter, and the target hiccup control signal; the input end of the driving unit 127 is connected to the output end of the reference unit 124, the output end of the lower bridge arm voltage detection unit 126, and the output end of the inductive current sampling unit 125, and the output end of the driving unit 127 is connected to the control end of each phase upper bridge arm switching tube, so that when the inductive current of each phase in the target solar photovoltaic grid-connected inverter increases to the reference current of the corresponding phase, the corresponding phase switching tube is turned off, and when the drain-source voltage of each phase lower bridge arm switching tube decreases to a preset voltage, the corresponding phase switching tube is turned on, so that the driving unit 127 can control the output current of the target solar photovoltaic grid-connected inverter by using a hiccup mode.
In addition, if the bus current on the direct current bus of the target solar photovoltaic grid-connected inverter is larger than the preset current value, the output current of the target solar photovoltaic grid-connected inverter is controlled by utilizing the hiccup mode, namely the output current of the target solar photovoltaic grid-connected inverter is controlled by utilizing the normal working mode.
Referring to fig. 6, fig. 6 is a structural diagram for controlling an output current of a target solar photovoltaic grid-connected inverter by using a normal operation mode according to an embodiment of the present invention. The input end of the reference unit 124 is connected to the output end of the bus voltage detection unit 121 and the output end of the alternating voltage and current detection unit 123, respectively, and is configured to generate each phase reference current according to the voltage and current at the output end of the target solar photovoltaic grid-connected inverter and the bus voltage of the direct current bus in the target solar photovoltaic grid-connected inverter; the input end of the driving unit 127 is connected to the output end of the reference unit 124, the output end of the lower bridge arm voltage detection unit 126, and the output end of the inductive current sampling unit 125, and the output end of the driving unit 127 is connected to the control end of each phase of upper bridge arm switching tube, respectively, for turning off the corresponding phase switching tube when the inductive current of each phase in the target solar photovoltaic grid-connected inverter increases to the corresponding phase reference current, and turning on the corresponding phase switching tube when the drain-source voltage of each phase of lower bridge arm switching tube decreases to a preset voltage.
Referring to fig. 7, fig. 7 is a schematic diagram of an output curve of the target solar photovoltaic grid-connected inverter in a normal operating mode and waveforms of the driving signals. Specifically, the preset voltage is a drain-source voltage value when the corresponding phase inductive current is zero, so that when the corresponding phase inductive current increases to the corresponding phase reference current, the corresponding phase switching tube is driven to be turned off, and when the corresponding phase inductive current is zero, the corresponding phase switching tube is driven to be turned on. In a half power frequency period, the driving signal of the obtained one-phase switch tube is shown as the waveform at the bottom of fig. 7, wherein tonIs the on-time, t, of the phase switching tubeoffThe turn-off time of the phase switching tube.
Referring to fig. 8, fig. 8 is a schematic diagram of the output current, the reference current and the switching tube driving signal of the target solar photovoltaic grid-connected inverter in the normal operating mode. When the inductive current of the target solar photovoltaic grid-connected inverter is increased to the reference current, the corresponding upper bridge arm switching tube Smos1 or Smos3 is turned off; when the inductive current of the target solar photovoltaic grid-connected inverter is reduced to zero, the corresponding upper bridge arm switching tube Smos1 or Smos3 is switched on, the driving control of the switching tube Smos1 comes from the first half period of the reference current, and the reference current of the second half period is used for driving the switching tube Smos3, namely, one reference current is used for carrying out time-sharing control on the two switching tubes.
Obviously, through the technical scheme provided by the embodiment, the control device of the solar photovoltaic grid-connected inverter can be further ensured to output high-quality alternating current.
Referring to fig. 9, fig. 9 is a flowchart of a control method of a solar photovoltaic grid-connected inverter according to an embodiment of the present invention, where the control method includes:
step S11: detecting the bus current of a direct current bus of a target solar photovoltaic grid-connected inverter;
step S12: and when the bus current is less than or equal to the preset current value, controlling the output current of the target solar photovoltaic grid-connected inverter by utilizing a hiccup mode.
For the control method of the solar photovoltaic grid-connected inverter provided in this embodiment, reference may be made to the disclosure of the control device of the solar photovoltaic grid-connected inverter disclosed in the foregoing embodiment, and details are not repeated in this embodiment.
The control method of the solar photovoltaic grid-connected inverter disclosed by the embodiment has the beneficial effects of the control device of the solar photovoltaic grid-connected inverter disclosed by the embodiment.
Based on the foregoing embodiments, this embodiment further describes and optimizes the technical solution, specifically, in step S12: when the bus current is less than or equal to the preset current value, the process of controlling the output current of the target solar photovoltaic grid-connected inverter by utilizing the hiccup mode comprises the following steps:
detecting the bus voltage of a direct current bus of a target solar photovoltaic grid-connected inverter;
when the bus current is smaller than or equal to a preset current value, generating a target hiccup control signal according to the bus current and the bus voltage;
acquiring voltage and current of an output end of a target solar photovoltaic grid-connected inverter;
generating reference current of each phase according to the voltage and current of the output end of the target solar photovoltaic grid-connected inverter, the bus voltage and the target hiccup control signal;
acquiring each phase of inductive current of a target solar photovoltaic grid-connected inverter;
detecting drain-source voltage of each phase lower bridge arm switching tube in a target solar photovoltaic grid-connected inverter;
when the current of each phase of inductor increases to the reference current of the corresponding phase, the corresponding phase of switching tube is turned off, and when the drain-source voltage of the bridge arm switching tube under each phase decreases to a preset voltage, the corresponding phase of switching tube is turned on so as to control the output current of the target solar photovoltaic grid-connected inverter by utilizing a hiccup mode;
the preset voltage is the drain-source voltage when the inductive current of each phase is zero.
For step S12 disclosed in this embodiment, reference may be made to corresponding contents of the bus voltage detecting unit, the hiccup controlling unit, the alternating voltage and current detecting unit, the reference unit, the inductive current sampling unit, the lower bridge arm voltage detecting unit, and the driving unit included in the hiccup controlling module disclosed in the foregoing embodiment, which are not described in detail in this embodiment.
Based on the above embodiments, this embodiment further describes and optimizes the technical solution, specifically, the steps are as follows: the process of generating each phase of reference current according to the voltage and current of the output end of the target solar photovoltaic grid-connected inverter, the bus voltage and the target hiccup control signal comprises the following steps:
and starting to generate each phase reference current according to the voltage and the current of the output end of the target solar photovoltaic grid-connected inverter, and stopping generating each phase reference current according to the bus voltage or the bus current.
It can be understood that, in the process of generating the reference current of each phase, the control device of the target solar photovoltaic grid-connected inverter must have the start time and the stop time for generating the reference current of each phase, so in this embodiment, the reference current of each phase can be generated according to the voltage and the current at the output end of the target solar photovoltaic grid-connected inverter, and the reference current of each phase is stopped to be generated according to the bus voltage or the bus current of the dc bus in the target solar photovoltaic grid-connected inverter, so that the reference current of each phase generated by the target solar photovoltaic grid-connected inverter can be more regular and orderly.
Therefore, by the technical scheme provided by the embodiment, the overall reliability of the target solar photovoltaic grid-connected inverter in the process of generating the reference current of each phase can be further ensured.
Specifically, the steps are as follows: the process of stopping generating the reference current of each phase according to the bus voltage or the bus current comprises the following steps:
and based on a preset direct proportional function, stopping generating reference current of each phase according to the bus current.
In practical application, the reference current of each phase can be stopped to be generated according to the bus current of the direct current bus of the target solar photovoltaic grid-connected inverter based on a preset direct proportional function. Because the target solar photovoltaic grid-connected inverter is controlled to stop generating the reference current of each phase through the mathematical model, the time for stopping generating the reference current of each phase can be more accurate and reliable. Specifically, the smaller the current value of the bus current, the larger the number of cycles for stopping generation of the reference current for each phase, and the larger the current value of the bus current, the smaller the number of cycles for stopping generation of the reference current for each phase.
Referring to fig. 10, fig. 10 is a schematic diagram of the voltage, the reference current and the output current of the ac power grid of the target solar photovoltaic grid-connected inverter in the hiccup mode. Specifically, the control device of the target solar photovoltaic grid-connected inverter may first generate a reference current of a half upper period, then stop generating the reference current of one period, and finally, continue generating the reference current of a half lower period again.
In addition, the time for the control device of the target solar photovoltaic grid-connected inverter to stop generating the reference current may be one cycle or may be a plurality of cycles. The method may be performed in any suitable manner, and is not particularly limited.
Obviously, by the technical scheme provided by the embodiment, the overall reliability of the target solar photovoltaic grid-connected inverter when the generated reference current of each phase is stopped can be further improved.
Specifically, the steps are as follows: the process of stopping generating the reference current of each phase according to the bus voltage or the bus current comprises the following steps:
and if the bus voltage is smaller than the preset voltage value, stopping generating the reference current of each phase.
In practical application, in order to further improve the accuracy of the control device of the solar photovoltaic grid-connected inverter when the control device stops generating the reference current of each phase, the bus voltage of the direct current bus can be compared with a preset voltage value, and the time for stopping generating the reference current can be controlled according to the comparison result of the bus voltage and the preset voltage value.
Specifically, if the bus voltage of the direct current bus is smaller than the preset voltage value, the control device of the solar photovoltaic grid-connected inverter is controlled to stop generating the reference current of each phase, so that the target solar photovoltaic grid-connected inverter can accumulate the energy of the output current of the target solar photovoltaic grid-connected inverter in the gap where the reference current of each phase stops generating, and the target solar photovoltaic grid-connected inverter can output the alternating current with higher quality.
Therefore, by the technical scheme provided by the embodiment, the accuracy of the control device of the solar photovoltaic grid-connected inverter when the control device stops generating the reference current of each phase can be further improved.
Based on the above embodiments, this embodiment further describes and optimizes the technical solution, specifically, the steps are as follows: the process of generating each phase of reference current according to the voltage and current of the output end of the target solar photovoltaic grid-connected inverter, the bus voltage and the target hiccup control signal comprises the following steps:
if the bus voltage is greater than or equal to the upper limit of the preset voltage range, starting to generate reference current of each phase;
and if the bus voltage is smaller than the lower limit of the preset voltage range, stopping generating the reference current of each phase.
In practical application, in the process of generating the reference current of each phase according to the bus voltage of the direct-current bus, the target solar photovoltaic grid-connected inverter may determine the time for starting to generate the reference current of each phase and the time for stopping generating the reference current of each phase according to a preset voltage range.
Specifically, if the bus voltage of the direct current bus of the target solar photovoltaic grid-connected inverter is greater than or equal to the upper limit of the preset voltage range, the target solar photovoltaic grid-connected inverter may start to generate the reference current of each phase, and if the bus voltage of the direct current bus of the target solar photovoltaic grid-connected inverter is less than the lower limit of the preset voltage range, the target solar photovoltaic grid-connected inverter may stop the reference current of each phase.
That is, when the bus voltage of the direct current bus rises to the upper limit of the preset voltage range, the hiccup mode is utilized to control the target solar photovoltaic grid-connected inverter to output the reference current of each phase; when the bus voltage of the direct current bus is larger than the lower limit of the preset voltage range and is smaller than or equal to the upper limit of the preset voltage range, the target solar photovoltaic grid-connected inverter is continuously controlled to output the reference current of each phase; and when the bus voltage of the direct current bus is smaller than the lower limit of the preset voltage range, controlling the target solar photovoltaic grid-connected inverter to stop outputting the reference current of each phase.
Therefore, by the technical scheme provided by the embodiment, the target solar photovoltaic grid-connected inverter can generate the reference current of each phase more flexibly and more variously.
The embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same or similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The control device and method for the solar photovoltaic grid-connected inverter provided by the invention are described in detail, specific examples are applied in the description to explain the principle and the implementation mode of the invention, and the description of the examples is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (6)
1. The utility model provides a controlling means of solar photovoltaic grid-connected inverter which characterized in that includes:
the bus current detection module is used for detecting the bus current of a direct current bus of the target solar photovoltaic grid-connected inverter;
the hiccup control module is used for controlling the output current of the target solar photovoltaic grid-connected inverter by using a hiccup mode when the bus current is less than or equal to a preset current value;
the hiccup control module comprises:
the bus voltage detection unit is used for detecting the bus voltage of a direct current bus of the target solar photovoltaic grid-connected inverter; the target solar photovoltaic grid-connected inverter is specifically a full-bridge inverter;
the hiccup control unit is used for generating a target hiccup control signal according to the bus current and the bus voltage when the bus current is smaller than or equal to a preset current value;
the alternating voltage and current detection unit is used for acquiring the voltage and the current of the output end of the target solar photovoltaic grid-connected inverter;
the reference unit is used for generating reference current of each phase according to the voltage and current of the output end of the target solar photovoltaic grid-connected inverter, the bus voltage and the target hiccup control signal;
the inductive current sampling unit is used for collecting each phase of inductive current of the target solar photovoltaic grid-connected inverter;
the lower bridge arm voltage detection unit is used for detecting the drain-source voltage of each phase of lower bridge arm switching tube in the target solar photovoltaic grid-connected inverter;
the driving unit is used for turning off the corresponding upper bridge arm switching tube when the inductive current of each phase is increased to the corresponding reference current of each phase, and turning on the corresponding upper bridge arm switching tube when the drain-source voltage of the corresponding lower bridge arm switching tube of each phase is reduced to a preset voltage so as to control the output current of the target solar photovoltaic grid-connected inverter by utilizing the hiccup mode; and the preset voltage is the drain-source voltage when the inductive current of each phase is zero.
2. A control method of a solar photovoltaic grid-connected inverter is characterized by comprising the following steps:
detecting the bus current of a direct current bus of a target solar photovoltaic grid-connected inverter;
when the bus current is smaller than or equal to a preset current value, controlling the output current of the target solar photovoltaic grid-connected inverter by utilizing a hiccup mode;
when the bus current is less than or equal to a preset current value, controlling the process of the output current of the target solar photovoltaic grid-connected inverter by utilizing a hiccup mode, wherein the process comprises the following steps:
detecting the bus voltage of a direct current bus of the target solar photovoltaic grid-connected inverter; the target solar photovoltaic grid-connected inverter is specifically a full-bridge inverter;
when the bus current is smaller than or equal to a preset current value, generating a target hiccup control signal according to the bus current and the bus voltage;
acquiring the voltage and the current of the output end of the target solar photovoltaic grid-connected inverter;
generating reference current of each phase according to the voltage and current of the output end of the target solar photovoltaic grid-connected inverter, the bus voltage and the target hiccup control signal;
collecting each phase of inductive current of the target solar photovoltaic grid-connected inverter;
detecting drain-source voltage of each phase lower bridge arm switching tube in the target solar photovoltaic grid-connected inverter;
when the inductance current of each phase is increased to the reference current of the corresponding phase, the upper bridge arm switching tube of the corresponding phase is turned off, and when the drain-source voltage of the lower bridge arm switching tube of each phase is reduced to a preset voltage, the upper bridge arm switching tube of the corresponding phase is turned on so as to control the output current of the target solar photovoltaic grid-connected inverter by utilizing the hiccup mode; and the preset voltage is the drain-source voltage when the inductive current of each phase is zero.
3. The control method according to claim 2, wherein the process of generating the reference current of each phase according to the voltage and the current of the output end of the target solar photovoltaic grid-connected inverter, the bus voltage and the target hiccup control signal comprises:
and starting to generate reference current of each phase according to the voltage and the current of the output end of the target solar photovoltaic grid-connected inverter, and stopping generating the reference current of each phase according to the bus voltage or the bus current.
4. The control method according to claim 3, wherein the process of stopping the generation of the reference currents for the respective phases based on the bus voltage or the bus current includes:
and based on a preset proportional function, stopping generating the reference current of each phase according to the bus current.
5. The control method according to claim 3, wherein the process of stopping the generation of the reference currents for the respective phases based on the bus voltage or the bus current includes:
and if the bus voltage is smaller than a preset voltage value, stopping generating the reference current of each phase.
6. The control method according to claim 3, wherein the process of generating the reference currents for each phase according to the voltage and current at the output end of the target solar photovoltaic grid-connected inverter, the bus voltage and the target hiccup control signal comprises:
if the bus voltage is greater than or equal to the upper limit of a preset voltage range, starting to generate the reference current of each phase;
and if the bus voltage is smaller than the lower limit of the preset voltage range, stopping generating the reference current of each phase.
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