CN221688322U - Photovoltaic energy storage system - Google Patents

Abstract

The utility model relates to a photovoltaic energy storage system which comprises a power grid, an output load, an inverter and a generator, wherein the power grid, the output load, the inverter and the generator are mutually communicated through a group of transmission lines, a first relay group is arranged on one side of the power grid, a second relay group is arranged on one side of the output load, and a third relay group is arranged on one side of the generator. Therefore, the photovoltaic energy storage system can be used for conveniently detecting faults of the relay.

Description

Photovoltaic energy storage system

Technical Field

The utility model relates to the field of electronics and electrical engineering, and in particular to a photovoltaic energy storage system.

Background Art

Photovoltaic energy storage system is a combination of equipment and technology that converts solar energy into electrical energy and supplies it to household appliances, while storing excess electrical energy for use at night or when there is no mains electricity. The main operating modes of photovoltaic energy storage systems include grid-connected operation mode and off-grid operation mode. The grid-connected operation mode includes realizing the energy flow of the inverter to the output load and the energy flow of the power grid to the output load. The off-grid energy storage inverter is mainly used in the off-grid operation mode when the off-grid energy storage inverter system is disconnected from the grid. It can control the energy flow of the off-grid inverter to the output load to achieve uninterrupted power supply to the output load. In the grid-connected or off-grid operation mode, a relay network needs to be placed on the grid side of the energy storage inverter system to ensure the normal operation of the inverter.

Both foreign TUV standards and my country's CGC standards require that the relay network connected between the inverter and the grid has a hardware fault self-detection function, that is, before the inverter is powered on and put into normal operation, it is necessary to detect whether the corresponding relay in the relay circuit can work normally. This mainly involves whether the contacts of the relay can make corresponding closing or releasing actions after the relay is energized or de-energized, that is, to detect whether there are open circuit and short circuit faults in the relay contacts.

The current inverters have mature relay self-test solutions, but for the newly emerging photovoltaic energy storage inverters in my country, especially for the relatively complex relay topology network in the energy storage system, not enough attention has been paid to the self-test method. The current technology mainly focuses on uninterrupted power transmission, and the relay is designed to provide uninterrupted power supply to the output load. The high reliability required by the certification standards is rarely considered, that is, the grid-side relay topology is designed from the perspective of relay self-fault detection, and the corresponding self-test control method is given.

Utility Model Content

The utility model is proposed in view of the above-mentioned prior art conditions, and its purpose is to provide a photovoltaic energy storage system that can conveniently detect relay faults itself.

To this end, the first aspect of the utility model provides a photovoltaic energy storage system, which includes a power grid, an output load, an inverter and a generator. The power grid, the output load, the inverter and the generator are interconnected through a group of transmission lines, a first relay group is provided on one side of the power grid, a second relay group is provided on one side of the output load, and a third relay group is provided on one side of the generator.

In addition, in the photovoltaic energy storage system involved in the utility model, optionally, when the power grid inputs a grid voltage, the fault conditions of the relays in the first relay group, the second relay group and the third relay group are judged according to the open or closed state of the relays in the first relay group, the second relay group and the third relay group, the output waveform state of the inverter, and the grid voltage, the load voltage of the output load, the inverter voltage of the inverter and the generator voltage of the generator.

In this case, the first relay group on one side of the power grid, the second relay group on one side of the output load, and the third relay group on one side of the generator can form a relay topology. The utility model can determine the fault conditions of the relays in the first relay group, the second relay group, and the third relay group according to the open or closed state of the relays in the first relay group, the second relay group, and the third relay group, the output waveform state of the inverter, and the power grid voltage, the load voltage of the output load, the inverter voltage of the inverter, and the generator voltage of the generator when the power grid inputs the power grid voltage, thereby realizing fault self-detection of the relay topology.

In addition, in the photovoltaic energy storage system involved in the utility model, optionally, the transmission line includes a live line and a neutral line, the first relay group includes a first relay arranged on the live line, and a third relay arranged on the neutral line, the second relay group includes a second relay arranged on the live line, and the third relay group includes a fourth relay group arranged on the live line. In this case, the relay topology is formed by the first relay and the third relay on one side of the power grid, the second relay on the output load side, and the fourth relay on the generator side. Through the relay fault detection method of the utility model, it is possible to easily detect the fault conditions of the first relay, the second relay, the third relay, and the fourth relay.

In addition, in the photovoltaic energy storage system involved in the utility model, optionally, the photovoltaic energy storage system also includes a control system, and the control system is configured to execute any of the above relay fault detection methods. In this case, it is convenient to execute the relay fault detection method through the control system, and then perform fault detection on the relays in the first relay group, the second relay group, and the third relay group.

In addition, in the photovoltaic energy storage system involved in the present invention, optionally, it also includes a photovoltaic component, a maximum power tracking controller, an energy storage device and a bidirectional charging and discharging circuit, the photovoltaic component is connected to the inverter through the maximum power tracking controller, and the energy storage device is connected to the inverter through the bidirectional charging and discharging circuit.

The utility model provides a photovoltaic energy storage system which can conveniently detect faults of relays themselves.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be explained in further detail by way of example only with reference to the accompanying drawings, in which:

FIG1 is a schematic structural diagram showing an embodiment of a photovoltaic energy storage system involved in this implementation example.

FIG. 2 is a schematic structural diagram showing another embodiment of a photovoltaic energy storage system according to the present embodiment.

Description of Reference Numerals

1…grid, 2…output load, 3…inverter, 4…generator, 5…control system, 6…photovoltaic panel, 7…MPPT controller, 8…energy storage device, 9…bidirectional charging and discharging circuit, K1…first relay, K2…second relay, K3…third relay, K4…fourth relay.

DETAILED DESCRIPTION

Hereinafter, with reference to the accompanying drawings, the preferred embodiments of the present invention will be described in detail. In the following description, the same symbols are assigned to the same components, and repeated descriptions are omitted. In addition, the accompanying drawings are only schematic diagrams, and the ratio of the dimensions of the components or the shapes of the components may be different from the actual ones.

It should be noted that the terms "including" and "having" and any variations thereof in the present invention, such as a process, method, system, product or device that includes or has a series of steps or units, are not necessarily limited to those steps or units clearly listed, but may include or have other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

The embodiments of the utility model relate to a photovoltaic energy storage system and a relay fault detection method of the photovoltaic energy storage system. Specifically, the utility model is used to detect faults of relays in a relay topology in a photovoltaic energy storage system.

FIG1 is a schematic structural diagram showing an embodiment of a photovoltaic energy storage system involved in this implementation example.

1 , the first aspect of the present invention provides a relay fault detection method for a photovoltaic energy storage system. The photovoltaic energy storage system includes a power grid 1 , an output load 2 , an inverter 3 and a generator 4 .

In some examples, the power grid 1 , the output load 2 , the inverter 3 , and the generator 4 may be interconnected via a set of transmission lines.

In some examples, a first relay group may be provided at one side of the power grid 1 .

In some examples, a second relay group may be provided on one side of the output load 2 .

In some examples, a third relay group may be provided on one side of the generator 4 .

In some examples, the output load 2 may be a household appliance or the like.

In the utility model, the fault detection method for the above-mentioned first relay group, second relay group and third relay group can be as follows: when the grid voltage Vi is input to the grid 1, the fault conditions of the relays in the first relay group, the second relay group and the third relay group can be judged according to the open or closed state of the relays in the first relay group, the second relay group and the third relay group, the output waveform state of the inverter 3, and the grid voltage Vi, the load voltage Vo of the output load 2, the inverter voltage Vinv of the inverter 3 (that is, the voltage at the AC output end of the inverter) and the generator voltage Vg of the generator 4.

In this case, the first relay group on one side of the power grid 1, the second relay group on one side of the output load 2, and the third relay group on one side of the generator 4 can form a relay topology. The utility model can determine the fault conditions of the relays in the first relay group, the second relay group and the third relay group according to the open or closed state of the relays in the first relay group, the second relay group and the third relay group, the output waveform state of the inverter 3, the power grid voltage Vi, the load voltage Vo of the output load 2, the inverter voltage Vi of the inverter 3 and the generator voltage Vg of the generator 4 when the power grid 1 is input with the power grid voltage Vi, thereby realizing fault self-detection of the relay topology.

In some examples, each group of transmission lines may include a live line L and a neutral line N. The first relay group may include a first relay K1 disposed on the live line L, and a third relay K3 disposed on the neutral line N. The second relay group may include a second relay K2 disposed on the live line L. The third relay group may include a fourth relay K4 disposed on the live line L. The first relay K1 may be used to control the on-off of the live line L on one side of the power grid 1, and the third relay K3 may be used to control the on-off of the neutral line N on one side of the power grid 1. The second relay K2 may be used to control the on-off of the live line L on one side of the output load 2. The fourth relay K4 may be used to control the on-off of the live line L on one side of the generator 4.

In this case, the relay topology can be formed by the first relay K1 and the third relay K2 on one side of the power grid 1, the second relay K2 on one side of the output load 2, and the fourth relay K4 on one side of the generator 4. Through the relay fault detection method of the utility model, the fault conditions of the first relay K1, the second relay K2, the third relay K3 and the fourth relay K4 can be easily detected.

The following is a detailed description of the fault detection method of the first relay K1 , the second relay K2 , the third relay K3 , and the fourth relay K4 .

In some examples, the failures of the first relay K1 , the second relay K2 , the third relay K3 , and the fourth relay K4 may include a short circuit failure and an open circuit failure.

In some examples, the fault detection sequence of the first relay K1 , the second relay K2 , the third relay K3 , and the fourth relay K4 is not particularly limited.

In some examples, fault detection may be performed on relays in a relay topology in sequence according to a preset order.

In some examples, when the grid 1 inputs the grid voltage Vi, the first relay K1, the second relay K2 and the fourth relay K4 are controlled to be disconnected, the third relay K3 is controlled to be closed, and the inverter 3 does not output a waveform. If the inverter voltage Vinv is equal to the grid voltage Vi, it can be determined that the first relay K1 has a short-circuit fault; if the inverter voltage Vinv is not equal to the grid voltage Vi, it can be determined that the first relay K1 has no short-circuit fault. In this way, it is convenient to detect whether the first relay K1 has a short-circuit fault.

In some examples, when the grid voltage Vi is input to the grid, the second relay K2, the third relay K3 and the fourth relay K4 are controlled to be disconnected, the first relay K1 is controlled to be closed, and the inverter does not output a waveform. If the inverter voltage Vinv is equal to the grid voltage Vi, it is determined that the third relay K3 has a short-circuit fault; if the inverter voltage Vinv is not equal to the grid voltage Vi, it is determined that the third relay K3 has no short-circuit fault. In this way, it is convenient to detect whether the third relay K3 has a short-circuit fault.

In some examples, when the grid voltage Vi is input to the grid, the first relay K1, the second relay K2 and the third relay K3 are controlled to be closed, the fourth relay K4 is controlled to be disconnected, and the inverter does not output a waveform. If the generator voltage Vg is not equal to the grid voltage Vi, it is determined that the fourth relay K4 has a short circuit fault; if the inverter voltage Vinv is not equal to the grid voltage Vi, it is determined that the fourth relay K4 has no short circuit fault. In this way, it is convenient to detect whether the fourth relay K4 has a short circuit fault.

In some examples, when the grid voltage Vi is input to the grid, the first relay K1, the third relay K3 and the fourth relay K4 are controlled to be closed, the second relay K2 is controlled to be disconnected, and the inverter does not output a waveform. If the load voltage Vo is equal to the grid voltage Vi, it is determined that the second relay K2 has a short circuit fault; if the load voltage Vo is not equal to the grid voltage Vi, it is determined that the second relay K2 has no short circuit fault. In this way, it is convenient to detect whether the second relay K2 has a short circuit fault.

In some examples, when the grid voltage Vi is input to the grid, the second relay K2 and the fourth relay K4 are controlled to be disconnected, the first relay K1 and the third relay K3 are controlled to be closed, and the inverter does not output a waveform. If the inverter voltage Vinv is not equal to the grid voltage Vi, it is determined that the first relay K1 and the third relay K3 have an open circuit fault; if the inverter voltage Vinv is not equal to the grid voltage Vi, it is determined that the first relay K1 and the third relay K3 do not have an open circuit fault. In this way, it is convenient to detect whether the first relay K1 and the third relay K3 have an open circuit fault.

In some examples, when the grid voltage Vi is input to the grid, the first relay K1, the second relay K2, the third relay K3 and the fourth relay K4 are controlled to be closed, and the inverter does not output a waveform. If the load voltage Vo is not equal to the grid voltage Vi, it is determined that the second relay K2 has an open circuit fault; if the generator voltage Vg is not equal to the grid voltage Vi, it is determined that the fourth relay K4 has an open circuit fault. In this way, it is convenient to detect whether the fourth relay K4 has an open circuit fault.

In some examples, the photovoltaic energy storage system further includes a control system 5 , and the control system 5 can be configured to execute the above-mentioned relay fault detection method. In this case, the relay fault detection method can be conveniently executed by the control system 5 .

The relay fault detection method of the utility model is simple and reliable, can be applied to a digitally controlled energy storage inverter system, and is easy to implement through programming.

In some examples, the photovoltaic energy storage system of the present invention may be an off-grid photovoltaic energy storage system. The present invention may be a self-test method for a relay topology applied to an off-grid photovoltaic energy storage system. In this case, the relay fault detection method of the present invention may effectively provide uninterrupted power supply requirements for the output load 2 in an off-grid mode.

In the utility model, since the grid voltage Vi, the inverter voltage Vinv, the load voltage Vo, and the generator voltage Vg are signals after data collection in the photovoltaic energy storage system, the corresponding effective values can be obtained by programming in the program. Therefore, the method of the utility model does not require additional hardware, has the advantages of low cost and high reliability, and can be suitable for engineering applications.

In some examples, the relay fault detection method of the present invention can be applied not only in photovoltaic energy storage systems, but also in wind power generation energy storage systems.

FIG. 2 is a schematic structural diagram showing another embodiment of a photovoltaic energy storage system according to the present embodiment.

Referring to Figure 2, the second aspect of the utility model provides a photovoltaic energy storage system, which may include a power grid 1, an output load 2, an inverter 3, a generator 4, a control system 5, a first relay group, a second relay group, and a third relay group. The power grid 1, the output load 2, the inverter 3, and the generator 4 can be interconnected through a group of transmission lines, respectively. A first relay group can be provided on one side of the power grid 1, a second relay group can be provided on one side of the output load 2, and a third relay group can be provided on one side of the generator. The control system 5 can be configured to execute the above-mentioned relay fault detection method of the photovoltaic energy storage system. In this case, the relay fault detection method of the utility model can be conveniently executed through the control system 5.

The utility model provides a photovoltaic energy storage system and a relay fault detection method thereof which can conveniently detect the fault of the relay itself.

In some examples, the photovoltaic energy storage system of the present invention further includes a photovoltaic assembly 6, a maximum power point tracking (MPPT) controller 7, an energy storage device 8, and a bidirectional charging and discharging circuit 9. The photovoltaic assembly 6 can be connected to the inverter 3 through the maximum power point tracking controller, and the energy storage device 8 can be connected to the inverter 3 through the bidirectional charging and discharging circuit 9.

In some examples, the photovoltaic assembly 6 may include a plurality of photovoltaic modules (also called solar panels), and the photovoltaic assembly 6 may be responsible for capturing sunlight and converting it into direct current electricity and then outputting it to the maximum power tracking controller 7 .

In some examples, the inverter 3 can be used to convert the direct current generated by the photovoltaic assembly 6 into alternating current for use by household appliances (output load 2), and can store excess electricity in the energy storage device 8. In some examples, when applied to a grid-connected photovoltaic energy storage system, the inverter 3 can also connect excess electricity to the city power grid.

In some examples, the energy storage device 8 can store the electrical energy generated by the photovoltaic assembly 6 but not used immediately through the inverter 3 for later use. In some examples, the energy storage device can include an energy storage battery.

In some examples, the bidirectional charging and discharging circuit 9 can be used to control the bidirectional transmission of electric energy, that is, the storage and use of electric energy can be controlled.

Although the present invention is specifically described above in conjunction with the accompanying drawings and examples, it is to be understood that the above description does not limit the present invention in any form. Those skilled in the art may modify and change the present invention as needed without departing from the spirit and scope of the present invention, and these modifications and changes all fall within the scope of the present invention.

Claims (5)

1. A photovoltaic energy storage system, characterized in that the photovoltaic energy storage system includes a power grid, an output load, an inverter and a generator, wherein the power grid, the output load, the inverter and the generator are interconnected through a group of transmission lines, a first relay group is provided on one side of the power grid, a second relay group is provided on one side of the output load, and a third relay group is provided on one side of the generator. 2. The photovoltaic energy storage system according to claim 1 is characterized in that the transmission line includes a live wire and a neutral wire, the first relay group includes a first relay arranged on the live wire and a third relay arranged on the neutral wire, the second relay group includes a second relay arranged on the live wire, and the third relay group includes a fourth relay group arranged on the live wire. 3. The photovoltaic energy storage system according to claim 1 is characterized in that, when the grid inputs a grid voltage, the fault conditions of the relays in the first relay group, the second relay group and the third relay group are judged according to the open or closed state of the relays in the first relay group, the second relay group and the third relay group, the output waveform state of the inverter, and the grid voltage, the load voltage of the output load, the inverter voltage of the inverter and the generator voltage of the generator. 4. The photovoltaic energy storage system according to claim 1, characterized in that the photovoltaic energy storage system also includes a control system, and the control system is configured to control the relays in the first relay group, the second relay group, and the third relay group to perform fault detection. 5. The photovoltaic energy storage system according to claim 1 is characterized in that it also includes a photovoltaic component, a maximum power tracking controller, an energy storage device and a bidirectional charging and discharging circuit, wherein the photovoltaic component is connected to the inverter through the maximum power tracking controller, and the energy storage device is connected to the inverter through the bidirectional charging and discharging circuit.