CN115912488A - New energy power generation device coupling system and coupling method - Google Patents
New energy power generation device coupling system and coupling method Download PDFInfo
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- CN115912488A CN115912488A CN202211654393.9A CN202211654393A CN115912488A CN 115912488 A CN115912488 A CN 115912488A CN 202211654393 A CN202211654393 A CN 202211654393A CN 115912488 A CN115912488 A CN 115912488A
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Abstract
The embodiment of the invention provides a coupling system and a coupling method for a new energy power generation device. Wherein, this system includes: the system comprises at least three groups of power generation devices, a grid-connected converter connected with the power generation devices, a transformer, a first switch and a second switch; the target group power generation device is coupled with at least one group of power generation devices through a first switch to realize direct current side coupling, the target group power generation device is coupled with at least one group of power generation devices through a second switch to realize low-voltage grid-connected side coupling, and the switching of different line grid-connected modes is realized by adjusting the on-off combination mode of the first switch and the second switch; the power generation devices which respectively realize direct current side coupling and low-voltage grid-connected side coupling with the target group power generation device are different groups of power generation devices. The invention realizes the conversion of different line grid-connected modes by adjusting the on-off combination relation of the switches, thereby improving the system stability.
Description
Technical Field
The invention relates to the technical field of new energy power generation, in particular to a coupling system and a coupling method of a new energy power generation device.
Background
With the rapid development of new energy, new energy in various forms can be connected to a power grid for power generation, wherein the comprehensive utilization of wind energy, solar energy and stored energy is the current main energy form. In order to reasonably and efficiently utilize the energy sources, a wind-solar-storage coupling alternating-current high-voltage side coupling system is mainly adopted at present, namely wind-solar-storage alternating current is coupled at a high-voltage grid-connected side, and a fan, an energy storage battery and a photovoltaic power generation device are all provided with corresponding converters and box transformers, but the coupling mode is single, and the system stability is not high.
Disclosure of Invention
The embodiment of the invention aims to provide a coupling system and a coupling method of a new energy power generation device, which can improve the stability of the system. The specific technical scheme is as follows:
the invention provides a new energy power generation device coupling system, which comprises:
the system comprises at least three groups of power generation devices, a grid-connected converter connected with the power generation devices, a transformer, a first switch and a second switch;
the low-voltage side of the transformer is connected with the grid-connected converter;
the target group power generation device is coupled with at least one group of power generation devices through the first switch to realize direct current side coupling, the target group power generation device is coupled with at least one group of power generation devices through the second switch to realize low-voltage grid-connected side coupling, and the switching of different line grid-connected modes is realized by adjusting the on-off combination mode of the first switch and the second switch;
the power generation devices which are respectively coupled with the direct current side and the low-voltage grid-connected side of the target group of power generation devices are different groups of power generation devices.
Optionally, the high-voltage side of the transformer is connected to a power grid, and the number of the transformers is smaller than the number of the groups of the power generation devices.
Optionally, the method further includes:
a third switch;
the third switch is arranged between a grid-connected converter connected with a power generation device realizing direct current side coupling with the target group power generation device and a corresponding transformer;
and the switching of different line grid-connected modes is realized by adjusting the on-off combination mode of the first switch, the second switch and the third switch.
Optionally, the method further includes:
a fourth switch;
the fourth switch is arranged between a grid-connected converter and a corresponding transformer, wherein the grid-connected converter is connected with a power generation device which realizes low-voltage grid-connected side coupling with the target group power generation device;
and the switching of different line grid-connected modes is realized by adjusting the on-off combination mode of the first switch, the second switch, the third switch and the fourth switch.
Optionally, the power generation device is one or more of a fan, an energy storage battery, and a photovoltaic power generation device.
In the alternative,
the grid-connected converter connected with the fan is a wind energy converter;
the grid-connected converter connected with the energy storage battery is an energy storage converter;
and the grid-connected converter connected with the photovoltaic power generation device is a photovoltaic inverter.
Alternatively to this, the first and second parts may,
the wind energy converter comprises a rectifier and a first inverter;
the energy storage converter comprises a first DC/DC converter and a second inverter;
the photovoltaic inverter includes a second DC/DC converter and a third inverter.
Optionally, the method further includes:
a master controller;
at least one grid-connected converter is controlled by the master controller;
the master controller is respectively connected with the switches;
and the master controller controls the on-off combination mode of each switch so as to realize the conversion of different line grid-connected modes.
Optionally, the method further includes:
a plurality of sub-controllers in communication with each other;
each grid-connected converter is controlled by a corresponding sub-controller;
each switch is controlled by at least one sub-controller;
and the sub-controller controls the on-off combination mode of each switch so as to realize the conversion of different line grid-connected modes.
The invention also provides a new energy power generation device coupling method, which is applied to the new energy power generation device coupling system, and the method comprises the following steps:
detecting whether faults occur in each grid-connected converter and each transformer in the new energy power generation device coupling system;
and when any fault of each grid-connected converter and each transformer is detected, switching the on-off state of a switch in the coupling system of the new energy power generation device and the operation state of the corresponding grid-connected converter.
Optionally, when any fault occurs, the on-off state of the switch and the operating state of the corresponding grid-connected converter are switched, including:
switching the on-off states of the first switch and the second switch under the condition that only the first fault occurs, and controlling a grid-connected converter connected with a target group power generation device to stop running;
and the first fault is the fault of a grid-connected converter connected with the target group of power generation devices and/or the fault of a transformer connected with the second switch.
Optionally, when any fault occurs, the on-off state of the switch and the operation state of the corresponding grid-connected converter are switched, including:
under the condition of first fault and second fault, switching the on-off states of a first switch, a second switch and a third switch, and controlling a grid-connected converter connected with a target group power generation device to stop running and a grid-connected converter connected with the third switch to stop running;
the first fault is a fault of a grid-connected converter connected with the target group of power generation devices, and/or a fault of a transformer connected with the second switch; and the second fault is the fault of the grid-connected converter and/or the transformer connected with the third switch.
Optionally, when any fault occurs, the on-off state of the switch and the operating state of the corresponding grid-connected converter are switched, including:
under the condition that only a second fault occurs, switching the on-off states of a first switch and a third switch, and controlling a grid-connected converter connected with the third switch to stop running;
and the second fault is the fault of the grid-connected converter and/or the transformer connected with the third switch.
Optionally, the detecting whether each grid-connected converter and each transformer in the new energy power generation device coupling system have a fault includes:
detecting whether a first fault occurs; the first fault is a fault of a grid-connected converter connected with the target group of power generation devices, and/or a fault of a transformer connected with the second switch;
detecting whether a second fault occurs; and the second fault is the fault of the grid-connected converter and/or the transformer connected with the third switch.
Optionally, before any fault of each grid-connected converter and each transformer is detected, the method further includes:
and each grid-connected converter and each transformer are in a normal operation state.
Optionally, the grid-connected converters and the transformers are in a normal operation state, including:
the wind turbine and/or the photovoltaic power generation device are normally connected to the grid when meeting the power dispatching instruction;
when the output of any one of the fan and the photovoltaic power generation device is insufficient, the energy storage battery outputs power to the power grid; and the number of the first and second groups,
when the power generation limit of any one of the fan and the photovoltaic power generation device is exceeded, the energy storage battery stores the electric energy.
According to the coupling system and the coupling method for the new energy power generation device, the target group power generation device is coupled with at least one group of power generation devices through the first switch at the direct current side, the target group power generation device is coupled with at least one group of power generation devices through the second switch at the low voltage grid-connected side, and the switching of different line grid-connected modes is realized by adjusting the on-off combination mode of the first switch and the second switch. The invention realizes the conversion of different line grid-connected modes by adjusting the on-off combination relation of the switches, and can improve the system stability.
Of course, it is not necessary for any product to practice the invention to achieve all of the above-described advantages at the same time.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a structural diagram of a coupling system of a new energy power generation apparatus according to an embodiment of the present invention;
fig. 2 is a structural diagram of another coupling system of a new energy power generation apparatus according to an embodiment of the present invention;
fig. 3 is a structural diagram of another coupling system of a new energy power generation apparatus according to an embodiment of the present invention;
fig. 4 is a structural diagram of another coupling system of a new energy power generation apparatus according to an embodiment of the present invention;
fig. 5 is a structural diagram of another coupling system of a new energy power generation apparatus according to an embodiment of the present invention;
fig. 6 is a structural diagram of a coupling system of another new energy power generation apparatus according to an embodiment of the present invention;
fig. 7 is a structural diagram of another coupling system of a new energy power generation apparatus according to an embodiment of the present invention;
fig. 8 is a structural diagram of a coupling system of another new energy power generation device according to an embodiment of the present invention;
fig. 9 is a structural diagram of a coupling system of another new energy power generation device according to an embodiment of the present invention;
fig. 10 is a flowchart of a coupling method of a new energy power generation apparatus according to an embodiment of the present invention;
fig. 11 is a schematic diagram of a coupling method of a new energy power generation apparatus according to an embodiment of the present invention;
fig. 12 is a schematic view of a coupling system of a new energy power generation apparatus corresponding to mode 1 according to an embodiment of the present invention;
fig. 13 is a schematic view of a coupling system of a new energy power generation apparatus corresponding to mode 2 according to an embodiment of the present invention;
fig. 14 is a schematic view of a coupling system of a new energy power generation device corresponding to mode 3 according to an embodiment of the present invention;
fig. 15 is a schematic view of a coupling system of a new energy power generation apparatus corresponding to mode 4 in an embodiment of the present invention.
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.
The invention provides a new energy power generation device coupling system, which comprises: the system comprises at least three groups of power generation devices, a grid-connected converter connected with the power generation devices, a transformer, a first switch and a second switch.
The new energy power generation device coupling system at least comprises three groups of power generation devices, the power generation types of the three groups of power generation devices can be the same or different, and the power generation types of the same group of power generation devices can be the same. The power generation device can comprise a new energy power generation device, and each set of power generation device can comprise one power generation device or a plurality of power generation devices. The output ends of the power generation devices are connected with the input ends of the grid-connected converters, and one group of power generation devices can be connected with one grid-connected converter.
The low-voltage side of the transformer is connected with the grid-connected converter. Specifically, the low-voltage side of the transformer is connected with the output ends of the grid-connected converters, the output end of one grid-connected converter can be connected with one transformer, the output ends of a plurality of grid-connected converters can be connected with the same transformer, and under the condition that the plurality of grid-connected converters are connected with the same transformer, the number of transformers can be reduced compared with the condition that each grid-connected converter is connected with different transformers.
Optionally, the high-voltage side of the transformer is connected to a power grid, and the number of the transformers is smaller than the number of the groups of the power generation devices. When the number of the transformers is multiple, the high-voltage sides of the transformers are connected, and the high-voltage sides of the transformers are connected with a power grid. In order to save cost, the invention can adopt a mode of connecting a plurality of grid-connected converters with the same transformer, so that the number of the transformers is less than the group number of the power generation devices. Alternatively, the transformer may be a box transformer.
The target group power generation device is coupled with at least one group of power generation devices through a first switch to achieve direct current side coupling, the target group power generation device is coupled with at least one group of power generation devices through a second switch to achieve low-voltage grid-connected side coupling, and switching of different line grid-connected modes is achieved by adjusting the on-off combination mode of the first switch and the second switch. When an inversion unit of a converter connected with a certain power generation device and connected with a network fails, the inversion unit can be shared by switching the switches, so that the stability of the system is improved.
The power generation devices which respectively realize direct current side coupling and low-voltage grid-connected side coupling with the target group power generation devices are different groups of power generation devices; the direct current side of the direct current side coupling is connected with the direct current sides of the DC/AC converters of the plurality of grid-connected converters; the low-voltage grid-connected side is coupled in such a way that the alternating current output sides of a plurality of grid-connected converters are connected with the low-voltage side of the same transformer, and the alternating current output side of the grid-connected converter is the alternating current side of a DC/AC converter of the grid-connected converter.
To further illustrate that the present invention can realize the conversion of different line grid-connected modes by adjusting the on-off combination of the first switch and the second switch, as shown in fig. 1, a new energy power generation device coupling system is provided, which includes three groups of power generation devices, namely, a first group of power generation devices, a target group of power generation devices, and a second group of power generation devices; the two transformers are respectively a first transformer T1 and a second transformer T2; the three grid-connected converters are respectively a first grid-connected converter connected with the first group of power generation devices, a second grid-connected converter connected with the target group of power generation devices and a third grid-connected converter connected with the second group of power generation devices, and the three grid-connected converters comprise DC/AC converters; the system further comprises a first switch k1 and a second switch k2. The first, second, and third grid-connected inverters include, in addition to the DC/AC inverter, an inverter (not shown in fig. 1), such as an AC/DC converter or a DC/DC converter, connected to each power generation device.
In fig. 1, the target group of power generation devices is coupled to the second group of power generation devices through the first switch k1, that is, the second grid-connected converter is connected to the DC side of the DC/AC converter in the third grid-connected converter when the first switch k1 is closed. The target group of power generation devices are coupled with the first group of power generation devices through the second switch k2, namely when the second switch k2 is closed, the alternating current side of the DC/AC converter in the second grid-connected converter and the alternating current side of the DC/AC converter in the first grid-connected converter are both connected with the low-voltage side of the first transformer T1, and the high-voltage side of the T1 is connected with the power grid.
When the first switch k1 is closed and the second switch k2 is opened, the target group of power generation devices and the second group of power generation devices are connected with the second transformer T2 through the DC/AC converter in the third grid-connected converter and then are connected with the grid, and the first group of power generation devices are connected with the first transformer T1 through the first grid-connected converter and then are connected with the grid.
When the first switch k1 is turned off and the second switch k2 is turned on, the target group of power generation devices are connected with the first transformer T1 through the second grid-connected converter and the first group of power generation devices through the second grid-connected converter and then are connected with the grid, and the second group of power generation devices are connected with the second transformer T2 through the third grid-connected converter and then are connected with the grid.
When the first switch k1 is closed and the second switch k2 is closed, the second group of power generation devices can be connected with the first transformer T1 through the DC/AC converter in the second grid-connected converter and then connected to the grid, and can also be connected with the second transformer T2 through the third grid-connected converter and then connected to the grid. The target group of power generation devices can be connected with the first transformer T1 through the second grid-connected converter and then connected with the grid, and can also be connected with the second transformer T2 through the DC/AC converter in the third grid-connected converter and then connected with the grid. The first group of power generation devices can be connected with the first transformer T1 through the first grid-connected converter and then connected with a grid.
When the first switch k1 is disconnected and the second switch k2 is disconnected, the first group of power generation devices are connected with the first transformer T1 through the first grid-connected converter and then are connected with the grid, the second group of power generation devices are connected with the second transformer T2 through the third grid-connected converter and then are connected with the grid, and the target group of power generation devices are not connected with the grid.
In summary, the switching between the different line grid-connected modes can be realized by adjusting the on-off combination mode of the first switch and the second switch. Once the box transformer or the DC-AC inverter fails, the grid-connected mode of the line is switched through the switch, so that the problem that the system cannot run or the generated energy is lost can be avoided, the number of transformers is saved, and the fault tolerance of the system is enhanced.
As an optional implementation manner, the new energy power generation apparatus coupling system provided by the present invention, as shown in fig. 2, further includes: and a third switch k3.
The third switch is arranged between the grid-connected converter connected with the generating set which realizes direct current side coupling with the target group generating set and the corresponding transformer.
In fig. 2, the power generation device that is DC-side coupled to the target group of power generation devices is the second group of power generation devices, the grid-connected inverter connected to the second group of power generation devices is the third grid-connected inverter, and the third switch is disposed between the third grid-connected inverter and the second transformer, that is, the third switch k3 is disposed between the DC/AC inverter in the third grid-connected inverter and the second transformer T2.
When the first switch k1 is closed and the second switch k2 is opened, if the third switch k3 is opened, the second group of power generation devices is connected with the target group of power generation devices, and at the moment, if the second group of power generation devices are new energy power generation devices and the target group of power generation devices are energy storage power sources, or the second group of power generation devices are energy storage batteries and the target group of power generation devices are new energy devices, after the second group of power generation devices are connected with the target group of power generation devices, the energy storage batteries can be charged through the new energy power generation devices, and therefore the loss of system power generation amount is reduced. When the first switch k1 is closed and the second switch k2 is opened, if the third switch k3 is closed, such a situation is the same as the situation where the first switch k1 is closed and the second switch k2 is opened as shown in fig. 1, and details thereof are not repeated.
When the first switch k1 is disconnected, the second switch k2 is closed, if the third switch k3 is disconnected, the target group of power generation devices are connected with the first transformer T1 through the first grid-connected converter and the first group of power generation devices through the second grid-connected converter and then are connected to the grid, and the second group of power generation devices are not connected to the grid. When the first switch k1 is turned off, the second switch k2 is turned on, and if the third switch k3 is turned on, this situation is the same as the situation where the first switch k1 is turned off and the second switch k2 is turned on as shown in fig. 1, and thus the description is omitted.
When the first switch k1 is closed, the second switch k2 is closed, and if the third switch k3 is open, the second group of power generation devices can be connected with the first transformer T1 through the DC/AC converter in the second grid-connected converter and then grid-connected, and the target group of power generation devices can be connected with the first transformer T1 through the second grid-connected converter and then grid-connected. When the first switch k1 is closed, the second switch k2 is closed, and if the third switch k3 is closed, this situation is the same as the situation that the first switch k1 is closed and the second switch k2 is closed as shown in fig. 1, and details are not repeated here.
When the first switch k1 is disconnected, the second switch k2 is disconnected, and if the third switch k3 is disconnected, the first group of power generation devices are connected with the first transformer T1 through the first grid-connected converter and then are connected to the grid, and the target group of power generation devices and the second group of power generation devices are not connected to the grid. When the first switch k1 is turned off, the second switch k2 is turned off, and if the third switch k3 is turned on, this situation is the same as the situation where the first switch k1 is turned on and the second switch k2 is turned off as shown in fig. 1, and thus the description is omitted.
In summary, by adjusting the on-off combination mode of the first switch, the second switch and the third switch, the conversion of different line grid-connected modes can be realized.
As another alternative embodiment, the present invention provides a new energy power generation device coupling system, as shown in fig. 3, the system further includes: a fourth switch k4.
And the fourth switch is arranged between the grid-connected converter connected with the power generation device which realizes low-voltage grid-connected side coupling with the target group of power generation devices and the corresponding transformer.
In fig. 3, the power generation device coupled to the target group of power generation devices on the low-voltage grid-connected side is the first group of power generation devices, the converter connected to the first group of power generation devices is the first grid-connected converter, the fourth switch is arranged between the first grid-connected converter and the first transformer, that is, the fourth switch k4 is arranged between the DC/AC converter in the first grid-connected converter and the first transformer T1.
When the fourth switch k4 is closed, the various line grid-connected modes of the system shown in fig. 3 are the same as those of the system shown in fig. 2, and are not described again.
When the fourth switch k4 is turned off, if the first switch is turned on, the second switch is turned off, the third switch is turned on, the target group of power generation devices and the second group of power generation devices are connected with the second transformer T2 through the DC/AC converter in the third grid-connected converter and then are connected with the grid, and the first group of power generation devices are not connected with the grid.
When the fourth switch k4 is turned off, if the first switch is turned on, the second switch is turned off, the third switch is turned off, the second group of power generation devices is connected with the target group of power generation devices, at this time, if the second group of power generation devices are new energy power generation devices, the target group of power generation devices are energy storage power sources, or the second group of power generation devices are energy storage batteries, the target group of power generation devices are new energy devices, and after the second group of power generation devices are connected with the target group of power generation devices, the energy storage batteries can be charged through the new energy power generation devices, so that the loss of system power generation amount is reduced. The first group of power generation devices, the target group of power generation devices and the second group of power generation devices are not connected to the grid.
When the fourth switch k4 is turned off, if the first switch k1 is turned off, the second switch k2 is turned on, the third switch k3 is turned on, the target group of power generation devices is connected with the first transformer T1 through the second grid-connected converter and then is connected to the grid, the second group of power generation devices is connected with the second transformer T2 through the third grid-connected converter and then is connected to the grid, and the first group of power generation devices is not connected to the grid.
When the fourth switch k4 is turned off, if the first switch k1 is turned off, the second switch k2 is turned on, the third switch k3 is turned off, the target group of power generation devices is connected with the first transformer T1 through the second grid-connected converter and then is connected to the grid, and the first group of power generation devices and the second group of power generation devices are not connected to the grid.
When the fourth switch k4 is opened, if the first switch k1 is closed, the second switch k2 is closed, and the third switch k3 is closed, the second group of power generation devices may be connected to the first transformer T1 through the DC/AC converter in the second grid-connected converter and then grid-connected, or may be connected to the second transformer T2 through the third grid-connected converter and then grid-connected. The target group of power generation devices can be connected with the first transformer T1 through the second grid-connected converter and then connected with the grid, and can also be connected with the second transformer T2 through the DC/AC converter in the third grid-connected converter and then connected with the grid. The first group of power plants is not grid connected.
When the fourth switch k4 is turned off, if the first switch k1 is turned on, the second switch k2 is turned on, and the third switch k3 is turned off, the second group of power generation devices can be connected with the first transformer T1 through the DC/AC converter in the second grid-connected converter and then grid-connected, and the target group of power generation devices can be connected with the first transformer T1 through the second grid-connected converter and then grid-connected. The first group of power plants is not grid connected.
When the fourth switch k4 is turned off, if the first switch k1 is turned off, the second switch k2 is turned off, the third switch k3 is turned on, the second group of power generation devices is connected with the second transformer T2 through the third grid-connected converter and then is connected to the grid, and the first group of power generation devices and the target group of power generation devices are not connected to the grid.
When the fourth switch k4 is turned off, if the first switch k1 is turned off, the second switch k2 is turned off, the third switch k3 is turned off, and none of the first group of power generation devices, the target group of power generation devices, and the second group of power generation devices is connected to the grid.
In summary, the switching of different line grid-connected modes can be realized by adjusting the on-off combination mode of the first switch, the second switch, the third switch and the fourth switch.
For fig. 1, 2 and 3, the three sets of power generation devices are one or more of a wind turbine, an energy storage battery and a photovoltaic power generation device.
As an alternative embodiment, the first group of power generation devices in fig. 1, 2 and 3 is a fan, the target group of power generation devices is an energy storage battery, and the second group of power generation devices is a photovoltaic power generation device.
In this embodiment, as shown in fig. 4, the coupling system of the new energy power generation device according to the present invention includes: a fan 71, an energy storage battery 72, and a photovoltaic power generation device 73; the grid-connected converter connected with the fan is a wind energy converter 74; the grid-connected converter connected with the energy storage battery is an energy storage converter 75; the grid-connected converters connected to the photovoltaic power generation apparatus are a photovoltaic inverter 76, a first transformer T1, a second transformer T2, a first switch k1, a second switch k2, a third switch k3, and a fourth switch k4, which may be a relay.
The wind power converter 74 comprises a rectifier 741, which is an AC/DC converter, and a first inverter 742; the energy storage converter 75 includes a first DC/DC converter 751 and a second inverter 752; the photovoltaic inverter 76 includes a second DC/DC converter 761 and a third inverter 762. The first inverter 742, the second inverter 752, and the third inverter 762 are all DC/AC converters.
In fig. 4, switching between different line grid-connected modes can be realized by adjusting the on-off combination of the first switch k1, the second switch k2, the third switch k3 and the fourth switch k4. The on/off state is 1, the off state is 0, and the line grid-connected modes are 16 in total and respectively as follows:
k1k2k3k4＝1010，k1k2k3k4＝1000，k1k2k3k4＝1011，k1k2k3k4＝1001；
k1k2k3k4＝0110，k1k2k3k4＝0100，k1k2k3k4＝0111，k1k2k3k4＝0101；
k1k2k3k4＝1110，k1k2k3k4＝1100，k1k2k3k4＝1111，k1k2k3k4＝1101；
k1k2k3k4＝0010，k1k2k3k4＝0000，k1k2k3k4＝0011，k1k2k3k4＝0001。
the output voltage of the alternating current side of the wind energy converter is consistent with that of the DC/AC converter of the energy storage converter, and when the second switch k2 and the fourth switch k4 are closed, the alternating current side of the DC/AC converter is in coupling connection, so that the alternating current low-voltage side coupling is realized, the number of transformers is saved, and the system cost is reduced.
The DC/DC output ends of the energy storage converter and the DC/DC converter of the photovoltaic inverter are coupled when the first switch k1 is closed, so that DC side coupling is realized, and the fault tolerance of the system is enhanced.
The energy storage converter can not output power to the power grid, and when the photovoltaic inverter is in derating operation or in abnormal state and cannot operate, the DC/AC converter in the energy storage converter works to output power to the power grid.
The conversion of different line grid-connected modes is realized by the on-off combination of the control switches K1-K4, so that the number of transformers is reduced, and the mutual backup and use of the DC/AC converter and the transformers are ensured. The switches K1 to K4 may be relays.
As an alternative embodiment, the energy storage battery and the photovoltaic power generation device in fig. 4 can be interchanged, and as shown in fig. 5, after the energy storage battery and the photovoltaic power generation device are interchanged, the energy storage converter and the photovoltaic inverter can also be interchanged.
As another alternative embodiment, when the three sets of power generation devices are respectively a fan, a photovoltaic power generation device and an energy storage battery, the coupling system of the new energy power generation device provided by the present invention may also be as shown in fig. 6, on the basis of fig. 6, the energy storage battery and the fan may exchange positions, as shown in fig. 7, after the energy storage battery and the fan exchange positions, the energy storage converter and the wind energy converter also exchange positions.
As an optional implementation manner, the new energy power generation device coupling system provided by the present invention further includes: and a master controller.
At least one grid-connected converter is controlled by a master controller;
the master controller is respectively connected with each switch;
the master controller controls the on-off combination mode of each switch so as to realize the conversion of different line grid-connected modes.
Optionally, a master controller is added on the basis of the coupling system of the new energy power generation device shown in fig. 4, as shown in fig. 8, a master controller 111 of the system is respectively connected with the wind energy converter 74, the energy storage converter 75, the photovoltaic inverter 76, the first switch k1, the second switch k2, the third switch k3 and the fourth switch k4, and the master controller can control the on-off combination mode of the switches k1-k4 to realize the conversion of different line grid-connected modes.
As another optional implementation, the new energy power generation device coupling system provided by the present invention further includes: a plurality of sub-controllers in communication with each other.
Each grid-connected converter is controlled by a corresponding sub-controller;
each switch is controlled by at least one sub-controller;
and the sub-controller controls the on-off combination mode of each switch so as to realize the conversion of different line grid-connected modes.
Optionally, three sub-controllers are added on the basis of the new energy power generation device coupling system shown in fig. 4, as shown in fig. 9, the three sub-controllers are respectively a controller 1, a controller 2 and a controller 3, and the controller 1, the controller 2 and the controller 3 may communicate with each other. The controller 1 is respectively connected with the wind energy converter 74 and the fourth switch k4, the controller 2 is respectively connected with the energy storage converter 75 and the second switch k2, the controller 3 is respectively connected with the photovoltaic inverter 76 and the third switch k3, and the first switch k1 is respectively connected with the controller 1, the controller 2 and the controller 3. The controller 1 controls the switch k4, the controller 2 controls the switch k2, the controller 3 controls the switch k3, and at least one of the controller 1, the controller 2 and the controller 3 controls the switch k1, so that one of the three controllers can be used as a main controller to change the combination mode of the switches k1-k4, thereby realizing the conversion of different line grid-connected modes and ensuring the mutual backup use of the DC/AC converter and the transformer.
The invention further provides a new energy power generation device coupling method, which is applied to the new energy power generation device coupling system, as shown in fig. 10, and the method comprises the following steps:
step 1001: and detecting whether faults occur in each grid-connected converter and each transformer in the new energy power generation device coupling system.
Step 1002: when any fault of each grid-connected converter and each transformer is detected, the on-off state of a switch in a coupling system of the new energy power generation device and the operation state of the corresponding grid-connected converter are switched.
As an optional implementation manner, when any fault occurs, the switching on/off state of the switch and the operation state of the corresponding grid-connected converter include:
switching the on-off states of the first switch and the second switch under the condition that only the first fault occurs, and controlling a grid-connected converter connected with a target group power generation device to stop running;
the first fault is that the grid-connected converter connected with the target group power generation device is in fault, and/or the transformer connected with the second switch is in fault.
As shown in fig. 4, the target group power generation device may be the energy storage battery in fig. 4, the first fault may be a fault of the DC/AC converter 752 in the energy storage converter, the first fault may also be a fault of the transformer T1, and the first fault may also be a fault of both the DC/AC converter 752 and the transformer T1. When the first fault occurs, the DC/AC converter 752 stops running, the second switch k2 can be changed from closed to open, the energy storage battery cannot be connected to the grid through the transformer T1 when the second switch k2 is open, and the first switch k1 can be changed from open to closed, so that the grid connection of the energy storage battery through the transformer T1 is realized.
As another optional implementation, when any fault occurs, the switching on/off state of the switch and the operation state of the corresponding grid-connected converter include:
under the condition of a first fault and a second fault, switching the on-off states of a first switch, a second switch and a third switch, and controlling a grid-connected converter connected with a target group power generation device to stop running and a grid-connected converter connected with the third switch to stop running;
the first fault is that the grid-connected converter connected with the target group power generation device is in fault, and/or the transformer connected with the second switch is in fault; the second failure is a failure of the grid-connected converter and/or transformer connected to the third switch.
As shown in fig. 4, the target group power generation device may be the energy storage battery in fig. 4, the first fault may be a fault of the DC/AC converter 752 in the energy storage converter, the first fault may also be a fault of the transformer T1, and the first fault may also be a fault of both the DC/AC converter 752 and the transformer T1. The second failure is a failure of at least one of the DC/AC converter 762 and the transformer T2 in the photovoltaic inverter. Under the condition that the first fault and the second fault occur, the DC/AC converter 752 and the DC/AC converter 762 stop operating, the second switch k2 and the third switch k3 can be changed from closed to open, and under the condition that the switches k2 and k3 are both open, the first storage switch k1 can be changed from open to closed, so that the electric energy generated by the photovoltaic can be stored by using the energy storage battery, and the waste of power generation is avoided.
As another optional implementation manner, when any fault occurs, the on-off state of the switch and the operation state of the corresponding grid-connected converter are switched, including:
under the condition that only the second fault occurs, switching the on-off states of the first switch and the third switch, and controlling a grid-connected converter connected with the third switch to stop running;
and the second fault is the fault of the grid-connected converter and/or the transformer connected with the third switch.
As shown in fig. 4, the target group power generation device may be the energy storage battery in fig. 4, and the second failure is a failure of at least one of the DC/AC converter 762 and the transformer T2 in the photovoltaic inverter. Under the condition of second fault, the DC/AC converter 762 stops running, the second switch k2 is closed at the moment, and the first switch k1 can be changed from open to closed, so that the grid connection of the photovoltaic power generation device through the DC/AC converter 752 in the energy storage converter and then through the transformer T1 can be realized.
As another optional implementation, detecting whether each grid-connected converter and each transformer in the new energy power generation device coupling system have a fault includes:
detecting whether a first fault occurs; the first fault is that the grid-connected converter connected with the target group power generation device is in fault, and/or the transformer connected with the second switch is in fault;
detecting whether a second fault occurs; and the second fault is the fault of the grid-connected converter and/or the transformer connected with the third switch.
In practical applications, whether a first fault occurs or not may be detected first, and whether a second fault occurs or not may be detected when the first fault does not occur.
As an optional implementation manner, before any fault of each grid-connected converter and each transformer is detected, the method provided by the present invention further includes:
and each grid-connected converter and each transformer are in a normal operation state.
Optionally, each grid-connected converter and each transformer are in a normal operation state, including:
the wind turbine and/or the photovoltaic power generation device are normally connected to the grid when meeting the power dispatching instruction;
when the output of any one of the fan and the photovoltaic power generation device is insufficient, the energy storage battery outputs power to the power grid; and the number of the first and second groups,
when the power generation limit of any one of the fan and the photovoltaic power generation device is exceeded, the energy storage battery stores the electric energy.
When the power dispatching instruction is met, the fan and/or the photovoltaic power generation device can be normally connected to the grid. When the grid-connected output of the fan and/or the photovoltaic power generation device is insufficient, the energy storage battery responds to the scheduling requirement and outputs the output to assist the fan and/or the photovoltaic power generation device in supporting the power grid. When the photovoltaic power generation device is over-limited, the photovoltaic power generation device can reversely charge the energy storage battery to store energy. When the fan is over-limited, the alternating current output of the photovoltaic power generation device can be limited, the energy storage battery is charged through the direct current bus, the photovoltaic power generation device can also be used for normally outputting power, and the energy storage battery is reversely charged through the energy storage converter to store energy.
As shown in fig. 4, under the condition that the wind turbine and/or the photovoltaic power generation device is normally connected to the grid when the power scheduling instruction is satisfied, the first switch k1 may be turned off, and the third switch k3 and the fourth switch k4 may be turned on, or the first switch k1 and the second switch k2 may be turned off, and the third switch k3 and the fourth switch k4 may be turned on. When the fan output is insufficient, the first switch k1 can be turned off, and the second switch k2, the third switch k3 and the fourth switch k4 are all turned on.
When the photovoltaic power generation device is insufficient in output, the second switch k2 can be opened, and the first switch k1, the third switch k3 and the fourth switch k4 can be closed. When the fan is over-limited, the first switch k1 is opened, and the second switch k2, the third switch k3 and the fourth switch k4 can be closed. When the photovoltaic power generation device exceeds the limit, the first switch k1 and the fourth switch k4 can be closed, and the second switch k2 and the third switch k3 can be opened.
To further illustrate the new energy power generation device coupling method provided by the present invention, the method shown in fig. 11 will be described with reference to the new energy power generation device coupling system shown in fig. 4. The fourth switch k4 in fig. 4 can be considered to be in a closed state by the following method.
When each grid-connected converter and each transformer are in a normal operation state, the energy storage converter and the photovoltaic inverter operate normally, which is a mode 1: k1k2k3=011, namely k1 is open, and k2 and k3 are closed, so that the two branches of the energy storage and the photovoltaic can work normally respectively. The structure of the coupling system of the new energy power generation device in the mode 1 is shown in fig. 12.
And judging whether the DC/AC752 and/or the transformer T1 of the energy storage converter are abnormal or not, namely detecting whether the DC/AC752 and/or the transformer T1 have faults or not.
When the DC/AC752 and/or the transformer T1 of the energy storage converter fail, the energy storage branch fails, and the current of the energy storage battery can be connected to the grid through the photovoltaic inverter DC/AC762 and the transformer T2, which is a mode 2: k1k2k3=101, i.e. k1, k3 are closed and k2 is open, ensuring sufficient photovoltaic power generation and support for the power grid. The structure of the coupling system of the new energy power generation device in the mode 2 is shown in fig. 13.
And judging whether the DC/AC762 and/or the transformer T2 of the energy storage converter are abnormal or not, namely detecting whether the DC/AC762 and/or the transformer T2 are/is in failure or not.
When neither the DC/AC752 nor the transformer T1 of the energy storage converter fails, but the photovoltaic inverter DC/AC762 and/or the transformer T2 fails, the photovoltaic power generation apparatus may be connected to the grid through the energy storage converter DC/AC752 and the transformer 1, which is a mode 3: k1k2k3=110, namely k1 and k2 are closed, and k3 is opened, so that the photovoltaic power generation is recovered, and the system power generation loss is reduced. The structure of the coupling system of the new energy power generation device in the mode 3 is shown in fig. 14.
When the DC/AC752 and/or the transformer T1 of the energy storage converter fail and the photovoltaic inverter DC/AC762 and/or the transformer T2 fail, the photovoltaic current charges the energy storage, which is a mode 4:
K1K2K3=100, namely K1 is closed and K2 and K3 are opened, the system power generation loss can be reduced. The structure of the coupling system of the new energy power generation device in the mode 4 is shown in fig. 15.
According to the invention, the alternating current coupling is realized for the fan and the energy storage device, so that the number of transformers can be saved, and the system cost is reduced; by realizing direct current coupling of the photovoltaic power generation device and the energy storage battery, the fault tolerance of the system can be enhanced, and when a photovoltaic inverter or a corresponding transformer fails, grid-connected power generation can still be realized, so that the power generation loss of the system is reduced; when the energy storage converter or the corresponding transformer fails, grid-connected power generation can still be performed, and the friendliness of grid support is guaranteed.
It is 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. It should also be noted that 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 a … …" does not exclude the presence of another identical element in a process, method, article, or apparatus that comprises the element.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the system or system embodiments are substantially similar to the method embodiments and therefore are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for related points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Those of skill would further appreciate that the various illustrative components and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the components and steps of the various examples have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (16)
1. A new energy power generation device coupling system, comprising:
the system comprises at least three groups of power generation devices, a grid-connected converter connected with the power generation devices, a transformer, a first switch and a second switch;
the low-voltage side of the transformer is connected with the grid-connected converter;
the target group power generation device is coupled with at least one group of power generation devices through the first switch to realize direct current side coupling, the target group power generation device is coupled with at least one group of power generation devices through the second switch to realize low-voltage grid-connected side coupling, and the switching of different line grid-connected modes is realized by adjusting the on-off combination mode of the first switch and the second switch;
the power generation devices which are respectively coupled with the direct current side and the low-voltage grid-connected side of the target group of power generation devices are different groups of power generation devices.
2. The new energy generation device coupling system according to claim 1, wherein the high voltage side of the transformers is connected to a power grid, and the number of the transformers is smaller than the number of the groups of the generation devices.
3. The new energy power plant coupling system of claim 1, further comprising:
a third switch;
the third switch is arranged between a grid-connected converter connected with a power generation device which realizes direct-current side coupling with the target group power generation device and a corresponding transformer;
and the switching of different line grid-connected modes is realized by adjusting the on-off combination mode of the first switch, the second switch and the third switch.
4. The new energy power plant coupling system of claim 3, further comprising:
a fourth switch;
the fourth switch is arranged between a grid-connected converter connected with a power generation device which realizes low-voltage grid-connected side coupling with the target group power generation device and a corresponding transformer;
and the switching of different line grid-connected modes is realized by adjusting the on-off combination mode of the first switch, the second switch, the third switch and the fourth switch.
5. The new energy power generation device coupling system as claimed in any one of claims 1 to 4, wherein the power generation device is one or more of a wind turbine, an energy storage battery, and a photovoltaic power generation device.
6. The new energy power plant coupling system of claim 5,
the grid-connected converter connected with the fan is a wind energy converter;
the grid-connected converter connected with the energy storage battery is an energy storage converter;
and the grid-connected converter connected with the photovoltaic power generation device is a photovoltaic inverter.
7. The new energy power plant coupling system of claim 6,
the wind energy converter comprises a rectifier and a first inverter;
the energy storage converter comprises a first DC/DC converter and a second inverter;
the photovoltaic inverter includes a second DC/DC converter and a third inverter.
8. The new energy power plant coupling system as claimed in any one of claims 1 to 4, further comprising:
a master controller;
at least one grid-connected converter is controlled by the master controller;
the master controller is respectively connected with the switches;
and the master controller controls the on-off combination mode of each switch so as to realize the conversion of different line grid-connected modes.
9. The new energy power plant coupling system as claimed in any one of claims 1 to 4, further comprising:
a plurality of sub-controllers in communication with each other;
each grid-connected converter is controlled by a corresponding sub-controller;
each switch is controlled by at least one sub-controller;
and the sub-controller controls the on-off combination mode of each switch so as to realize the conversion of different line grid-connected modes.
10. A new energy power generation device coupling method applied to the new energy power generation device coupling system according to any one of claims 1 to 9, the method comprising:
detecting whether faults occur in each grid-connected converter and each transformer in the new energy power generation device coupling system;
and when any fault of each grid-connected converter and each transformer is detected, switching the on-off state of a switch in the coupling system of the new energy power generation device and the operation state of the corresponding grid-connected converter.
11. The new energy power generation device coupling method according to claim 10, wherein switching the on/off state of the switch and the operation state of the corresponding grid-connected converter when any fault occurs includes:
switching the on-off states of the first switch and the second switch under the condition that only the first fault occurs, and controlling a grid-connected converter connected with a target group power generation device to stop running;
and the first fault is the fault of a grid-connected converter connected with the target group of power generation devices and/or the fault of a transformer connected with the second switch.
12. The new energy power generation device coupling method according to claim 10, wherein switching the on/off state of the switch and the operation state of the corresponding grid-connected converter when any fault occurs includes:
under the condition of a first fault and a second fault, switching the on-off states of a first switch, a second switch and a third switch, and controlling a grid-connected converter connected with a target group power generation device to stop running and a grid-connected converter connected with the third switch to stop running;
the first fault is a fault of a grid-connected converter connected with the target group of power generation devices, and/or a fault of a transformer connected with the second switch; and the second fault is the fault of the grid-connected converter and/or the transformer connected with the third switch.
13. The new energy power generation device coupling method according to claim 10, wherein switching the on/off state of the switch and the operation state of the corresponding grid-connected converter when any fault occurs includes:
under the condition that only a second fault occurs, switching the on-off states of a first switch and a third switch, and controlling a grid-connected converter connected with the third switch to stop running;
and the second fault is a fault of a grid-connected converter and/or a transformer connected with the third switch.
14. The method for coupling a new energy power generation device according to claim 10, wherein the detecting whether the grid-connected converters and the transformers in the new energy power generation device coupling system have faults comprises:
detecting whether a first fault occurs; the first fault is a fault of a grid-connected converter connected with the target group power generation device, and/or a fault of a transformer connected with the second switch;
detecting whether a second fault occurs; and the second fault is the fault of the grid-connected converter and/or the transformer connected with the third switch.
15. The new energy power plant coupling method of any one of claims 10 to 14, wherein before any fault is detected in each grid-connected inverter and each transformer, the method further comprises:
and each grid-connected converter and each transformer are in a normal operation state.
16. The method according to claim 15, wherein the step of coupling the grid-connected converters and the transformers to each other is performed in a normal operation state, and comprises the steps of:
the wind turbine and/or the photovoltaic power generation device are normally connected to the grid when meeting the power dispatching instruction;
when the output of any one of the fan and the photovoltaic power generation device is insufficient, the energy storage battery outputs power to the power grid; and (c) a second step of,
when any one of the fan and the photovoltaic power generation device is over-generation-limited, the energy storage battery stores electric energy.
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