CN219717898U - Energy storage inverter - Google Patents
Energy storage inverter Download PDFInfo
- Publication number
- CN219717898U CN219717898U CN202320492205.0U CN202320492205U CN219717898U CN 219717898 U CN219717898 U CN 219717898U CN 202320492205 U CN202320492205 U CN 202320492205U CN 219717898 U CN219717898 U CN 219717898U
- Authority
- CN
- China
- Prior art keywords
- bus capacitor
- energy storage
- grid
- direct current
- storage inverter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000004146 energy storage Methods 0.000 title claims abstract description 87
- 239000003990 capacitor Substances 0.000 claims abstract description 145
- 238000009413 insulation Methods 0.000 claims abstract description 26
- 238000001914 filtration Methods 0.000 claims abstract description 8
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 238000001514 detection method Methods 0.000 description 13
- 230000000694 effects Effects 0.000 description 11
- 238000000034 method Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 230000007935 neutral effect Effects 0.000 description 4
- 238000010248 power generation Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
Landscapes
- Inverter Devices (AREA)
Abstract
The embodiment of the utility model discloses an energy storage inverter, which comprises a direct current power supply, an inversion output module, a bus capacitor module and a switch, wherein the inversion output module is connected in parallel with the direct current power supply and is connected with a power grid; the bus capacitor module is used for filtering direct current transmitted by the direct current power supply to the inversion output module and comprises a first bus capacitor, a second bus capacitor, a first voltage-equalizing resistor and a second voltage-equalizing resistor, wherein the first bus capacitor and the second bus capacitor are connected in series on a branch connected with the direct current power supply in parallel, and the first voltage-equalizing resistor and the second voltage-equalizing resistor are respectively connected in parallel with the first bus capacitor and the second bus capacitor; the switch is used for switching the state that one end of the first bus capacitor connected in series with the second bus capacitor is connected with or disconnected from the power grid when the ground insulation resistance is detected or the grid connection mode and the off-grid mode are switched. The utility model is beneficial to improving the utilization rate of bus voltage and the reliability of the use of the energy storage inverter.
Description
Technical Field
The utility model relates to the technical field of data processing, in particular to an energy storage inverter.
Background
The energy storage inverter is equipment for converting a direct-current power supply into an alternating-current power supply and is mainly applied to an energy storage inverter of a photovoltaic, wind energy and nuclear energy power generation system. The power grid comprises a direct current input module and an inversion output module, wherein the inversion output module is used for converting direct current provided by the direct current input module into alternating current and outputting the converted alternating current to the power grid. At present, a bus midpoint in a direct current input module of the energy storage inverter is usually connected with a power grid N line, and in a TN system (called protection zero connection), the power grid N line is equipotential with the ground, so that the use of the energy storage inverter is not facilitated.
Disclosure of Invention
The embodiment of the utility model provides an energy storage inverter, which aims to improve the use effect of the energy storage inverter.
The embodiment of the utility model provides an energy storage inverter, which comprises:
a direct current power supply for supplying direct current;
the inversion output module is connected in parallel with the direct current power supply and connected with a power grid, and is used for converting the direct current into alternating current and outputting the alternating current to the power grid;
the bus capacitor module is used for filtering direct current transmitted by the direct current power supply to the inversion output module, and comprises a first bus capacitor, a second bus capacitor, a first voltage equalizing resistor and a second voltage equalizing resistor, wherein one end of the first bus capacitor is connected with the positive electrode of the direct current power supply, the other end of the first bus capacitor is connected with one end of the second bus capacitor in series, the other end of the second bus capacitor is connected with the negative electrode of the direct current power supply, the first voltage equalizing resistor is connected with the first bus capacitor in parallel, and the second voltage equalizing resistor is connected with the second bus capacitor in parallel; and
and one end of the switch is connected with one end of the first bus capacitor in series connection with one end of the second bus capacitor, the other end of the switch is connected with the power grid, and the switch is used for switching the state that one end of the first bus capacitor in series connection with the second bus capacitor is connected with or disconnected from the power grid when the ground insulation impedance is detected or the grid connection mode and the off-grid mode are switched.
Optionally, the first equalizing resistor and the second equalizing resistor are equal in size.
Optionally, the energy storage inverter further comprises a contactor module, and the contactor module is connected in series between the positive electrode of the direct current power supply and the first bus capacitor.
Optionally, the contactor module includes a main contactor, a soft start contactor, and a soft start resistor, the main contactor is connected in series between the positive electrode of the dc power supply and the first bus capacitor, the soft start contactor is connected in series with the soft start resistor, and the soft start contactor and the soft start resistor connected in series are connected in parallel with the main contactor.
Optionally, the contactor module includes a main contactor, a diode, and a soft start resistor, the main contactor is connected in series between the positive electrode of the dc power supply and the first bus capacitor, the diode is connected in series with the soft start resistor, and the diode and the soft start resistor connected in series are connected in parallel with the main contactor.
Optionally, the inversion output module includes three level inverter circuit and three phase line branch road, every phase line branch road's one end with three level inverter circuit is connected, every phase line branch road's the other end with the electric wire netting is connected.
Optionally, the three-level inverter circuit includes three bridge arms connected in parallel with the dc power supply, and each bridge arm is connected in series with a first switching tube and a second switching tube.
Optionally, an inverter inductor is disposed on each phase line branch.
Optionally, the inversion output module further includes three output filter capacitors, one end of each output filter capacitor is connected with one end of the first bus capacitor in series connection with one end of the second bus capacitor, and the other end of each output filter capacitor is connected with one end of the inversion inductor on one phase line branch connected with the power grid.
Optionally, a grid-connected switch connected with the inversion inductor in parallel is arranged on each phase line branch.
It can be seen that the energy storage inverter provided by the utility model comprises a direct current power supply, an inversion output module, a bus capacitor module and a switch. The direct current power supply is used for providing direct current; the inverter output module is connected in parallel with the direct current power supply and is connected with a power grid, the inverter output module is used for converting direct current into alternating current and outputting the alternating current to the power grid, the bus capacitor module is used for filtering the direct current which is transmitted to the inverter output module by the direct current power supply, the bus capacitor module comprises a first bus capacitor, a second bus capacitor, a first voltage equalizing resistor and a second voltage equalizing resistor, one end of the first bus capacitor is connected with the positive electrode of the direct current power supply, the other end of the first bus capacitor is connected with one end of the second bus capacitor in series, the other end of the second bus capacitor is connected with the negative electrode of the direct current power supply, the first voltage equalizing resistor is connected with the first bus capacitor in parallel, and the second voltage equalizing resistor is connected with the second bus capacitor in parallel; one end of the switch is connected with one end of the first bus capacitor connected in series with the second bus capacitor, the other end of the switch is connected with the power grid, and the switch is used for switching the state that one end of the first bus capacitor connected in series with the second bus capacitor is connected with or disconnected from the power grid when the ground insulation resistance is detected or the grid-connected mode and the off-grid mode are switched. Therefore, the energy storage inverter can correspondingly adjust the connection state of the midpoint of the bus and the power grid when detecting the ground insulation impedance or switching between the grid-connected mode and the off-grid mode by connecting the switch between one end (namely the midpoint of the bus) of the first bus capacitor and the second bus capacitor in series connection, so that the condition of dynamically adjusting the grounding of the midpoint of the bus can be realized, the reliability of the ground insulation impedance detection effect is improved, and the use effect of the energy storage inverter in the off-grid mode and the grid-connected mode is improved.
Drawings
In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the utility model, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic circuit diagram of an energy storage inverter in an open state of a switch Kn according to an embodiment of the present utility model;
fig. 2 is a schematic circuit diagram of an energy storage inverter in a closed state of a switch Kn according to an embodiment of the present utility model;
fig. 3 is a schematic circuit diagram of another energy storage inverter provided in an embodiment of the present utility model in an open state of the switch Kn;
fig. 4 is a schematic circuit diagram of another energy storage inverter provided in an embodiment of the present utility model when the switch Kn is in a closed state;
fig. 5 is a schematic circuit diagram of another energy storage inverter according to an embodiment of the present utility model;
fig. 6 is a schematic circuit diagram of another energy storage inverter according to an embodiment of the present utility model.
Detailed Description
In order that those skilled in the art will better understand the present utility model, a technical solution in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present utility model, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
The terms first, second and the like in the description and in the claims and in the above-described figures are used for distinguishing between different objects and not necessarily for describing a sequential or chronological order. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed steps or elements but may include other steps or elements not listed or inherent to such process, method, article, or apparatus.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the utility model. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.
The energy storage inverter is equipment for converting a direct-current power supply into an alternating-current power supply and is mainly applied to an energy storage inverter of a photovoltaic, wind energy and nuclear energy power generation system. The power grid comprises a direct current input module and an inversion output module, wherein the inversion output module is used for converting direct current provided by the direct current input module into alternating current and outputting the converted alternating current to the power grid. Currently, the bus midpoint in the dc input module of the energy storage inverter is usually connected to the grid N line, which is at an equipotential with the earth in a TN system (called a protection zero). While grounding the midpoint of the bus would present two problems. One problem is that the direct current insulation resistance to ground contains a voltage equalizing resistance when the direct current insulation resistance to ground is detected, so that abnormal faults of the battery to ground can be misreported when the insulation resistance to ground is detected on the energy storage inverter, and the normal operation of the energy storage inverter is seriously affected. Another problem is that since the grid voltage is a sine wave with only a fundamental wave, if two unequal voltage sources are forced to be in parallel to cause overcurrent when the energy storage inverter is connected in grid, the energy storage inverter cannot work normally. Therefore, the conventional sinusoidal pulse width modulation (SPWM, sinusoidal Pulse Width Modulation) mode is currently used in the normal case, thus sacrificing bus voltage utilization.
In order to solve the problems, the utility model provides an energy storage inverter, a control method thereof and a related device, wherein the energy storage inverter comprises a direct current power supply, an inversion output module, a bus capacitor module and a switch. The direct current power supply is used for providing direct current; the inverter output module is connected in parallel with the direct current power supply and is connected with a power grid, the inverter output module is used for converting direct current into alternating current and outputting the alternating current to the power grid, the bus capacitor module is used for filtering the direct current which is transmitted to the inverter output module by the direct current power supply, the bus capacitor module comprises a first bus capacitor, a second bus capacitor, a first voltage equalizing resistor and a second voltage equalizing resistor, one end of the first bus capacitor is connected with the positive electrode of the direct current power supply, the other end of the first bus capacitor is connected with one end of the second bus capacitor in series, the other end of the second bus capacitor is connected with the negative electrode of the direct current power supply, the first voltage equalizing resistor is connected with the first bus capacitor in parallel, and the second voltage equalizing resistor is connected with the second bus capacitor in parallel; one end of the switch is connected with one end of the first bus capacitor connected in series with the second bus capacitor, the other end of the switch is connected with the power grid, and the switch is used for switching the state that one end of the first bus capacitor connected in series with the second bus capacitor is connected with or disconnected from the power grid when the ground insulation resistance is detected or the grid-connected mode and the off-grid mode are switched. Therefore, the energy storage inverter provided by the utility model can correspondingly adjust the connection state of the midpoint of the bus and the power grid when detecting the ground insulation resistance or switching between the grid-connected mode and the off-grid mode by connecting the switch between one end (namely the midpoint of the bus) of the first bus capacitor and the second bus capacitor which are connected in series, so that the condition of dynamically adjusting the grounding of the midpoint of the bus can be realized, the reliability of the ground insulation resistance detection effect is improved, and the use effect of the energy storage inverter in the off-grid mode and the grid-connected mode is improved.
The following describes in further detail the embodiments of the present utility model with reference to the drawings and examples. The following examples are illustrative of the utility model and are not intended to limit the scope of the utility model.
Referring to fig. 1 to 6, an embodiment of the present utility model provides an energy storage inverter including a dc power supply for providing dc power, an inversion output module, a bus capacitor module, and a switch; the inversion output module is connected in parallel with the direct current power supply and connected with a power grid, and is used for converting the direct current into alternating current and outputting the alternating current to the power grid; the bus capacitor module is used for filtering direct current transmitted by the direct current power supply to the inversion output module, and comprises a first bus capacitor (namely Cbus1 in fig. 1-6), a second bus capacitor (namely Cbus2 in fig. 1-6), a first voltage equalizing resistor (namely R1 in fig. 1-6) and a second voltage equalizing resistor (namely R2 in fig. 1-6), wherein one end of the first bus capacitor is connected with the positive electrode of the direct current power supply, the other end of the first bus capacitor is connected with one end of the second bus capacitor in series, the other end of the second bus capacitor is connected with the negative electrode of the direct current power supply, the first voltage equalizing resistor is connected in parallel with the first bus capacitor, and the second voltage equalizing resistor is connected in parallel with the second bus capacitor; one end of the switch is connected with one end of the first bus capacitor in series connection with one end of the second bus capacitor, the other end of the switch is connected with the power grid, and the switch is used for switching the state that one end of the first bus capacitor in series connection with the second bus capacitor is connected with or disconnected from the power grid when the ground insulation impedance is detected or the grid connection mode and the off-grid mode are switched.
One end of the first bus capacitor and the second bus capacitor connected in series is a bus midpoint, namely BUSN in fig. 1 to 6.
The switch can be a relay to realize the functions of automatic adjustment, safety protection and a conversion circuit.
The inversion output module is used for converting direct current provided by the direct current power supply into alternating current and outputting the converted alternating current to a power grid outside the energy storage inverter. The inverter output module may be, for example, a single-phase grid-connected inverter output circuit or a three-phase grid-connected inverter output circuit. The power grid may be, for example, a utility power grid.
The first bus capacitor and the second bus capacitor which are connected in series in the bus capacitor module can filter direct current transmitted to the inversion output module, so that energy decoupling between the output power of the direct current power supply and the output power of the inversion output module is realized. The first bus capacitor and the second bus capacitor can also absorb high-frequency switching frequency and higher harmonic current generated by the energy storage inverter, and can be used for energy storage after boosting of the energy storage inverter, so that stable and pure direct current bus voltage of the energy storage inverter is guaranteed.
The first voltage equalizing resistor and the second voltage equalizing resistor in the bus capacitor module can be equal in size, namely, the first voltage equalizing resistor and the second voltage equalizing resistor are two resistors with equal resistance values. Therefore, the voltage equalizing effect can be achieved, and the possibility that the first bus capacitor and the second bus capacitor are damaged due to overvoltage breakdown is reduced due to the fact that the voltage on the first bus capacitor is different from the voltage on the second bus capacitor due to the individual difference of the first bus capacitor and the second bus capacitor is avoided.
Referring to fig. 1, 2, 3 or 4, in this embodiment, the energy storage inverter further includes a contactor module, and the contactor module is connected in series between the positive electrode of the dc power supply and the first bus capacitor.
In this example, the contactor module may function to turn on or off the power supply and have the effect of an under-voltage release. By connecting the contactor module in series between the positive pole of the battery and the first bus capacitor, the impact of the circuit of the energy storage inverter on the grid can be reduced.
Referring to fig. 5, in this embodiment, the contactor module includes a main contactor (i.e., K1 in fig. 5), a soft start contactor (i.e., K2 in fig. 5), and a soft start resistor (i.e., rs in fig. 5), the main contactor is connected in series between the positive electrode of the dc power supply and the first bus capacitor, the soft start contactor and the soft start resistor are connected in series, and the soft start contactor and the soft start resistor connected in series are connected in parallel to the main contactor.
In this example, if during operation a BUS negative (i.e., BUS in fig. 1-6) short to ground occurs, the voltage at the BUS positive (i.e., BUS in fig. 1-6) will rise, which may trigger a BUS neutral imbalance or half BUS hardware overvoltage. When this is detected, the energy storage inverter can avoid overvoltage damage of the first bus capacitor and the second bus capacitor by rapidly opening the soft start contactor and the switch.
Referring to fig. 6, in this embodiment, the contactor module includes a main contactor (i.e., K1 in fig. 6), a diode (i.e., D1 in fig. 6), and a soft start resistor (i.e., rs in fig. 6), the main contactor is connected in series between the positive electrode of the dc power supply and the first bus capacitor, the diode and the soft start resistor are connected in series, and the diode and the soft start resistor connected in series are connected in parallel to the main contactor.
In this example, if during operation a bus negative to ground short occurs, the voltage at the bus positive will rise, which may trigger a bus neutral imbalance or half bus hardware overvoltage. When this is detected, the energy storage inverter can avoid overvoltage damage of the first bus capacitor and the second bus capacitor by rapidly opening the switch.
Referring to fig. 3 or fig. 4, in this embodiment, the inversion output module includes a three-level inversion circuit and three phase line branches, one end of each phase line branch is connected to the three-level inversion circuit, and the other end of each phase line branch is connected to the power grid.
In this embodiment, the inversion output module is set to be a three-level inversion circuit and three phase line branches connected with the power grid, that is, the inversion output module is set to be a three-phase grid-connected inversion output circuit, so that the performance of the inversion output module is guaranteed to be excellent and safe, and the manufacturing difficulty and cost of the energy storage inverter are reduced.
Referring to fig. 3 or fig. 4, in this embodiment, the three-level inverter circuit includes three bridge arms connected in parallel with the dc power supply, and each bridge arm is connected in series with a first switching tube and a second switching tube.
In this embodiment, the first switching tube and the second switching tube on each bridge arm may be alternately turned on or off in a control period, so that three-phase ac power can be output to the power grid through three phase line branches.
Referring to fig. 3 or 4, in this embodiment, each phase line branch is provided with an inverter inductor (i.e., la, lb, lc in fig. 1 to 6).
One end of an inversion inductor on each phase line branch is connected with the three-level inversion circuit, and the other end of the inversion inductor is connected with a power grid. Specifically, when the three-level inverter circuit is provided with three bridge arms, one end of the inverter inductor on each phase line branch can be connected with one of the bridge arms, and the other end of the inverter inductor on each phase line branch can be connected with the power grid. In this example, the current passing through each phase line branch may be filtered by setting an inverter inductance in each phase line branch, so as to improve the utilization rate of the alternating current output by the inverter output module to the power grid.
Referring to fig. 3 or fig. 4, in this embodiment, the inverting output module further includes three output filter capacitors (i.e., ca, cb, cc in fig. 1 to fig. 6), one end of each output filter capacitor is connected to one end of the first bus capacitor connected in series with one end of the second bus capacitor, and the other end of each output filter capacitor is connected to one end of the inverting inductor on one phase line branch connected to the power grid.
In this example, the filter capacitor may further improve the filtering effect of the energy storage inverter, thereby further improving the utilization rate of the alternating current output by the inverter output module to the power grid.
Referring to fig. 3 or 4, in this embodiment, a grid-connected switch (i.e. Ka, kb, kc in fig. 1 to 6) connected in parallel with the inverter inductor is disposed on each phase line branch.
And a grid-connected switch is arranged on each phase line branch circuit, so that the working safety of the energy storage inverter can be ensured. Specifically, when the energy storage inverter does not work, the grid-connected switch on each phase line branch can be controlled to be disconnected, so that the three-level inverter circuit is ensured not to be connected with a power grid through each phase line branch, and potential safety hazards are avoided.
It can be seen that the energy storage inverter provided by the utility model comprises a direct current power supply, an inversion output module, a bus capacitor module and a switch. The direct current power supply is used for providing direct current; the inverter output module is connected in parallel with the direct current power supply and is connected with a power grid, the inverter output module is used for converting direct current into alternating current and outputting the alternating current to the power grid, the bus capacitor module is used for filtering the direct current which is transmitted to the inverter output module by the direct current power supply, the bus capacitor module comprises a first bus capacitor, a second bus capacitor, a first voltage equalizing resistor and a second voltage equalizing resistor, one end of the first bus capacitor is connected with the positive electrode of the direct current power supply, the other end of the first bus capacitor is connected with one end of the second bus capacitor in series, the other end of the second bus capacitor is connected with the negative electrode of the direct current power supply, the first voltage equalizing resistor is connected with the first bus capacitor in parallel, and the second voltage equalizing resistor is connected with the second bus capacitor in parallel; one end of the switch is connected with one end of the first bus capacitor connected in series with the second bus capacitor, the other end of the switch is connected with the power grid, and the switch is used for switching the state that one end of the first bus capacitor connected in series with the second bus capacitor is connected with or disconnected from the power grid when the ground insulation resistance is detected or the grid-connected mode and the off-grid mode are switched. Therefore, the energy storage inverter can correspondingly adjust the connection state of the midpoint of the bus and the power grid when detecting the ground insulation impedance or switching between the grid-connected mode and the off-grid mode by connecting the switch between one end (namely the midpoint of the bus) of the first bus capacitor and the second bus capacitor in series connection, so that the condition of dynamically adjusting the grounding of the midpoint of the bus can be realized, the reliability of the ground insulation impedance detection effect is improved, and the use effect of the energy storage inverter in the off-grid mode and the grid-connected mode is improved.
In a specific implementation, before the grid is connected with the power grid and started, the state of the switch can be detected, and the state of the switch comprises a closed state and an open state. And if the switch is in an off state, detecting the ground insulation impedance of the energy storage inverter. And if the switch is in the closed state, controlling the switch to be opened so as to enable the switch to be switched from the closed state to the open state, and detecting the ground insulation resistance of the energy storage inverter after the state of the switch is switched to the open state. After the energy storage inverter is subjected to ground insulation resistance detection, the switch can be controlled to be closed so as to be switched from the open state to the closed state. The grid-connected startup refers to starting up after the energy storage inverter and the power grid are connected. The energy storage inverter circuit can determine whether electricity in the bus is grounded or not by detecting the state of the switch, and the switch is in a closed state to indicate that the midpoint of the bus is communicated with the power grid, namely, the midpoint of the bus is grounded. The switch being in the open state indicates that the bus midpoint is not connected to the grid, i.e., the bus midpoint is not grounded.
Specifically, as shown in fig. 1, if the switch is in an off state, that is, the midpoint of the bus is not grounded currently, the resistance values of the first voltage-sharing resistor and the second voltage-sharing resistor will not affect the result of the detection of the insulation resistance to ground, and the detection circuit of the insulation resistance to ground can be invoked to detect the insulation resistance to ground at this time, so as to ensure the accuracy of the detection result. As shown in fig. 2, if the switch is in the closed state, it indicates that the midpoint of the bus is currently grounded, and the resistance values of the first voltage-equalizing resistor and the second voltage-equalizing resistor affect the result of the detection of the insulation resistance to ground. At this time, the switch can be controlled to be opened first, so that the switch is switched from the closed state to the open state, the midpoint of the bus is not grounded, and then the ground insulation impedance detection circuit can be called to perform ground insulation impedance detection so as to detect the output safety of the energy storage inverter.
Therefore, before the direct current side of the energy storage inverter passes through the ground insulation impedance detection, the switch is controlled to be in the off state, so that the first average resistance and the second average resistance cannot influence the result of the ground impedance detection of the energy storage inverter, and the accuracy of the ground impedance detection of the energy storage inverter is improved.
In a specific implementation, when the energy storage inverter is used, a use mode of the energy storage inverter can be determined, and the use mode of the energy storage inverter comprises a grid-connected mode and a grid-off mode. And if the using mode of the energy storage inverter is a grid-connected mode, controlling the switch to be in an off state, and calling the first modulation mode to modulate and send waves, wherein the first modulation mode is third harmonic injection sine wave pulse width modulation (SPWM, sinusoidal Pulse Width Modulation) or space vector pulse width modulation (SVPWM, space Vector Pulse Width Modulation). And if the using mode of the energy storage inverter is off-grid, controlling the switch to be in a closed state, and calling a first modulation mode or a second modulation mode to modulate and send waves, wherein the second modulation mode is sinusoidal pulse width modulation.
Specifically, as shown in fig. 3, if the usage mode of the energy storage inverter is the grid-connected mode, the energy required by the load connected to each phase line branch of the inverter output module may be provided by the power grid, and at this time, the midpoint of the bus may not be connected to the neutral line (N line) of the power grid. The switch can be controlled to be in an off state. As shown in fig. 4, if the usage mode of the energy storage inverter is off-grid, the energy required by the load connected to each phase line branch of the inverter output module needs to be provided by a dc power supply, and at this time, the midpoint of the bus may need to be connected to the neutral line (N line) of the power grid. So that the switch can be controlled to be in a closed state.
Specifically, when the control switch is in the off state, if the switch is in the off state before the use mode of the energy storage inverter is determined to be the grid-connected mode, the state may be maintained. If the switch is in the closed state before determining that the usage mode of the energy storage inverter is the grid-tie mode, the switch may be controlled to open to switch from the closed state to the open state. When the control switch is in the closed state, if the switch is in the closed state before the use mode of the energy storage inverter is determined to be the grid-connected mode, the state is maintained. If the switch is in an open state before determining that the usage mode of the energy storage inverter is a grid-tie mode, the switch may be controlled to be closed to switch from the open state to the closed state.
Therefore, when the energy storage inverter is in the off-grid mode or the grid-connected mode, the first modulation mode is called to modulate the wave, so that the utilization rate of the direct current bus voltage can be improved, and the use effect of the energy storage inverter in the off-grid mode and the grid-connected mode is improved. In addition, the first modulation mode or the second modulation mode is called to modulate the wave when the energy storage inverter is in the off-grid mode, so that the method can be suitable for different off-grid load conditions, and is beneficial to improving the utilization rate of the bus voltage and guaranteeing the reliability of use.
When the first modulation mode or the second modulation mode is called to modulate the wave, the off-grid load condition of the inversion output module in the off-grid mode can be determined first; to determine that the load requires several phase legs to supply power. The three-phase off-grid load refers to a load which needs to be powered by three phase line branches during off-grid. Single phase loads refer to loads that require one phase leg to power them when off-grid. When the load is determined to be a three-phase off-grid load, the first modulation mode can be called for modulating the wave so as to improve the utilization rate of the bus voltage. When the load is determined to be a single-phase off-grid load, the power supply requirement of the load is indicated to be met by one phase line branch, and in order to avoid the problem of uncleanness of voltage on the load, a second modulation mode can be selected for modulating the wave.
Therefore, in the example, the off-grid load condition is determined before the calling mode is selected, so that the accuracy of the selected calling mode can be improved, the improvement of the bus voltage utilization rate can be guaranteed, various conditions of the energy storage inverter during use can be dynamically adapted, the operation of the energy storage inverter in the off-grid mode is further guaranteed, and the use reliability of the energy storage inverter is improved.
The foregoing has outlined rather broadly the more detailed description of embodiments of the utility model, wherein the principles and embodiments of the utility model are explained in detail using specific examples, the above examples being provided solely to facilitate the understanding of the method and core concepts of the utility model; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present utility model, the present description should not be construed as limiting the present utility model in view of the above.
Claims (10)
1. An energy storage inverter, the energy storage inverter comprising:
a direct current power supply for supplying direct current;
the inversion output module is connected in parallel with the direct current power supply and connected with a power grid, and is used for converting the direct current into alternating current and outputting the alternating current to the power grid;
the bus capacitor module is used for filtering direct current transmitted by the direct current power supply to the inversion output module, and comprises a first bus capacitor, a second bus capacitor, a first voltage equalizing resistor and a second voltage equalizing resistor, wherein one end of the first bus capacitor is connected with the positive electrode of the direct current power supply, the other end of the first bus capacitor is connected with one end of the second bus capacitor in series, the other end of the second bus capacitor is connected with the negative electrode of the direct current power supply, the first voltage equalizing resistor is connected with the first bus capacitor in parallel, and the second voltage equalizing resistor is connected with the second bus capacitor in parallel; and
and one end of the switch is connected with one end of the first bus capacitor in series connection with one end of the second bus capacitor, the other end of the switch is connected with the power grid, and the switch is used for switching the state that one end of the first bus capacitor in series connection with the second bus capacitor is connected with or disconnected from the power grid when the ground insulation impedance is detected or the grid connection mode and the off-grid mode are switched.
2. The energy storage inverter of claim 1, wherein the first voltage balancing resistor is equal in size to the second voltage balancing resistor.
3. The energy storage inverter of claim 1, further comprising a contactor module connected in series between the positive pole of the dc power source and the first bus capacitor.
4. The energy storage inverter of claim 3, wherein the contactor module comprises a main contactor, a soft start contactor, and a soft start resistor, the main contactor being connected in series between the positive pole of the dc power source and the first bus capacitor, the soft start contactor and the soft start resistor being connected in series in parallel with the main contactor.
5. The energy storage inverter of claim 3, wherein the contactor module comprises a main contactor, a diode, and a soft start resistor, the main contactor being connected in series between the positive pole of the dc power source and the first bus capacitor, the diode and the soft start resistor being connected in series in parallel with the main contactor.
6. The energy storage inverter of claim 1, wherein the inverter output module comprises a three-level inverter circuit and three phase line branches, one end of each phase line branch is connected with the three-level inverter circuit, and the other end of each phase line branch is connected with the power grid.
7. The energy storage inverter of claim 6, wherein the three-level inverter circuit comprises three legs connected in parallel with the dc power source, each leg having a first switching tube and a second switching tube connected in series.
8. The energy storage inverter of claim 6, wherein each of said phase line branches is provided with an inverter inductance.
9. The energy storage inverter of claim 8, wherein the inverting output module further comprises three output filter capacitors, one end of each output filter capacitor is connected with one end of the first bus capacitor connected in series with one end of the second bus capacitor, and the other end of each output filter capacitor is connected with one end of the inverting inductor on one phase line branch connected with the power grid.
10. The energy storage inverter of claim 8, wherein each of the phase line branches is provided with a grid-tie switch in parallel with the inverter inductance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320492205.0U CN219717898U (en) | 2023-03-06 | 2023-03-06 | Energy storage inverter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320492205.0U CN219717898U (en) | 2023-03-06 | 2023-03-06 | Energy storage inverter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN219717898U true CN219717898U (en) | 2023-09-19 |
Family
ID=88004460
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202320492205.0U Active CN219717898U (en) | 2023-03-06 | 2023-03-06 | Energy storage inverter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN219717898U (en) |
-
2023
- 2023-03-06 CN CN202320492205.0U patent/CN219717898U/en active Active
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Bottrell et al. | Comparison of current-limiting strategies during fault ride-through of inverters to prevent latch-up and wind-up | |
| JP6357679B2 (en) | Method and apparatus for ground fault detection | |
| CN102611108B (en) | Three-level three-phase four-wire active power filter and control method thereof | |
| CN105119262B (en) | Realize that power quality adjusts the circuit with the active extinguishing arc of small current grounding fault simultaneously | |
| CN104578886A (en) | Pulse width modulation method for three-level photovoltaic inverter and modulator | |
| CN103441504A (en) | Series compensation low-voltage ride-through device with self-charging function and control method thereof | |
| Lazzari et al. | Selectivity and security of DC microgrid under line-to-ground fault | |
| CN112952867B (en) | Method for inhibiting unbalance of output voltage of energy storage power converter under asymmetric load | |
| CN109638791B (en) | Direct-current disconnection protection method of multi-terminal flexible direct-current power distribution system | |
| CN110868095A (en) | DC-AC inverter for ship regional power distribution | |
| CN104578736A (en) | Control method for converter current-limiting protection based on dynamic vector amplitude limit and converter | |
| CN112636312B (en) | Micro-grid protection method based on injected zero-sequence characteristic signal | |
| CN219717898U (en) | Energy storage inverter | |
| Zhang et al. | Current-Limiting Strategy for Asymmetric Short-Circuit of Three-Phase Inverter for Continuous Power Supply of Non-Faulty Loads | |
| CN103337949B (en) | A kind of redundancy protected method isolating two-stage chain-type energy storage system | |
| CN214674840U (en) | Bus capacitor pre-charging circuit, converter and motor control system | |
| CN214750546U (en) | Direct-current ground insulation impedance detection circuit for bridge arm topology converter | |
| CN115224724A (en) | Three-phase grid-connected connection method of energy storage system with filter capacitor | |
| CN107026475A (en) | A kind of distributed solar electricity generation system enters network control method | |
| CN116054264A (en) | Energy storage inverter, control method thereof and related device | |
| CN112379172A (en) | High-precision direct current ground insulation impedance detection circuit and method | |
| CN112379171A (en) | Direct-current ground insulation impedance detection circuit and method for bridge arm topology converter | |
| CN111525887A (en) | Grounding detection circuit and method for non-isolated photovoltaic inverter | |
| CN205809146U (en) | A kind of photovoltaic combining inverter leak current detection device | |
| CN110635472A (en) | Method for increasing carrying capacity of three-phase energy storage inversion system and three-phase energy storage inversion system applying same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |