System and method for improving generating capacity of light storage power station

Abstract

The invention relates to the technical field of photovoltaic power generation, in particular to a system and method for improving the generating capacity of a light storage power station. According to the invention, when a photovoltaic system operates in cloudy days or in the morning and other weak illumination conditions, electricity generated by a photovoltaic module is boosted by a DC / DC converter through a cable to charge an energy storage battery; under the condition of normal illumination, electricity generated by the photovoltaic module can be supplied to a power grid through the inverter or charge the energy storage system from the alternating current side of the inverter, and can also directly charge the energy storage battery according to the field condition, which is equivalent to a direct current coupling energy storage unit. Therefore, the electric quantity generated by the photovoltaic module cannot be abandoned under different weather conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation, and in particular to a system and method for increasing the power generation of a photovoltaic power station. Background Art

[0002] In rainy and snowy weather, although there is no direct sunlight, the power generation of the photovoltaic power station will be relatively low, but it does not mean that there is no power generation. Photovoltaic modules can also generate power to a certain extent under weak light conditions. However, in some special cases, if the solar radiation is too low and the working voltage of the photovoltaic power generation system cannot reach the starting voltage of the inverter, the system will not work.

[0003] The main wiring method of current photovoltaic power stations is: the direct current generated by photovoltaic modules is converted into alternating current through an inverter and directly fed to the load or sent to the power grid. The power grid can also charge the battery through a bidirectional DC-AC bidirectional converter. The energy collection point is at the AC end.

[0004] In summary, in the weak light conditions of the photovoltaic power station in the early morning or on cloudy days, the generated electricity cannot start the inverter because the component voltage is too low, and this part of the electricity will usually be discarded. The present invention uses a photovoltaic power station wiring method to directly store this part of the electricity in the energy storage device of the photovoltaic power station through DC / DC to increase the power generation of the photovoltaic power station. Summary of the invention

[0005] In response to the above problems, the present invention provides a system and method for improving the power generation of a photovoltaic power station, which is used to solve the problem that in the weak light conditions of the photovoltaic power station in the early morning or on cloudy days, the component voltage is too low and the generated electricity cannot start the inverter, so this part of the electricity will be discarded.

[0006] In a first aspect, the present invention provides a system for increasing the power generation of a photovoltaic power station, comprising:

[0007] Inverter branch and energy storage branch;

[0008] The inverter branch includes: the photovoltaic components are connected to the power grid in sequence through the inverter and the inverter branch circuit breaker;

[0009] The energy storage branch includes: a photovoltaic module connected to an energy storage battery through a diode and a DC / DC converter in sequence;

[0010] The energy storage battery system is connected to the power grid through the DC / AC converter, the first circuit breaker of the energy storage branch, the booster and the second circuit breaker of the energy storage branch in sequence;

[0011] Among them, photovoltaic modules are used for photovoltaic power generation; energy storage batteries are used for weak light energy storage or excess energy storage, and DC / DC converters have built-in circuit breakers;

[0012] The power generation direction of the photovoltaic module is selected through the inverter branch circuit breaker, the built-in circuit breaker of the DC / DC converter, the first circuit breaker of the energy storage branch and the second circuit breaker of the energy storage branch.

[0013] Furthermore, weak light energy storage is used when the photovoltaic system is running on cloudy days or in the early morning when the light is weak. The electricity generated by the photovoltaic panels is boosted through cables and DC / DC converters to charge the energy storage battery.

[0014] Furthermore, excess energy storage is used when the lighting is normal, and the electricity generated by the photovoltaic panels can be used to directly charge the energy storage battery according to the on-site conditions.

[0015] In a second aspect, the present invention provides a method for increasing the power generation of a photovoltaic power station, using the above-mentioned system for increasing the power generation of a photovoltaic power station.

[0016] When it is cloudy or the light is weak in the early morning, close the inverter branch circuit breaker, the first circuit breaker of the energy storage branch, and the second circuit breaker of the energy storage branch, open the built-in circuit breaker of the DC / DC converter, and the electricity generated by the photovoltaic module is boosted through the cable and the DC / DC converter to charge the energy storage battery;

[0017] When the sunlight is normal, open the inverter branch circuit breaker, close the first circuit breaker of the energy storage branch and the second circuit breaker of the energy storage branch, and the electricity generated by the photovoltaic module is connected to the grid through the inverter or charged to the energy storage system from the inverter AC measurement. At the same time, open or close the built-in circuit breaker of the DC / DC converter according to the on-site situation to select whether to directly charge the energy storage battery;

[0018] When the energy storage battery is discharged, the first circuit breaker of the energy storage branch and the second circuit breaker of the energy storage branch are opened, and the electricity generated by the energy storage battery is connected to the power grid through the DC / AC converter and the booster.

[0019] The present invention has at least the following beneficial effects:

[0020] The present invention enables the energy storage system to absorb the electricity in all photovoltaic strings. When the photovoltaic sub-array configuration is high, the inverter will limit the current. The previous wiring method cannot absorb the electricity in all photovoltaic strings.

[0021] The direct connection of photovoltaics to energy storage in the present invention can greatly reduce the costs associated with energy storage, including the equipment and EPC costs of AC switchgear, medium voltage transformers and related trenching.

[0022] The present invention can still utilize the electricity generated by the components when the lighting conditions such as rain, snow, cloudy days, and early mornings do not meet the inverter starting voltage, thereby reducing the abandoned light rate of the photovoltaic power station.

[0023] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 Schematic diagram of the system structure of an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the weak light conditions of the photovoltaic power station in the early morning or on cloudy days, the generated electricity cannot start the inverter because the component voltage is too low. Usually, this part of the electricity will be discarded. The present invention uses a photovoltaic power station wiring method to directly store this part of the electricity in the energy storage device of the photovoltaic power station through DC / DC to increase the power generation of the photovoltaic power station.

[0028] like Figure 1 As shown, the present invention provides a system for increasing the power generation of a photovoltaic power station, comprising:

[0029] Inverter branch and energy storage branch;

[0030] The inverter branch includes: the photovoltaic components are connected to the power grid in sequence through the inverter and the inverter branch circuit breaker;

[0031] The energy storage branch includes: a photovoltaic module connected to an energy storage battery through a diode and a DC / DC converter in sequence;

[0032] The energy storage battery system is connected to the power grid through the DC / AC converter, the first circuit breaker of the energy storage branch, the booster and the second circuit breaker of the energy storage branch in sequence;

[0033] Among them, photovoltaic modules are used for photovoltaic power generation; energy storage batteries are used for weak light energy storage or excess energy storage, and DC / DC converters have built-in circuit breakers;

[0034] The power generation direction of the photovoltaic module is selected through the inverter branch circuit breaker, the built-in circuit breaker of the DC / DC converter, the first circuit breaker of the energy storage branch and the second circuit breaker of the energy storage branch.

[0035] When it comes to specific implementation,

[0036] Figure 1 The basic design of the wiring method of the present invention is described. The energy storage battery is directly connected to the existing photovoltaic module through a DC / DC converter.

[0037] The working principle of the wiring method of the present invention is as follows: when the photovoltaic system is running under weak light conditions such as cloudy days or early mornings, the electricity generated by the photovoltaic module is boosted through the cable through the DC / DC converter to charge the energy storage battery; when the light is normal, the electricity generated by the photovoltaic module can be connected to the power grid through the inverter or charged to the energy storage system from the inverter AC measurement, or it can be directly charged to the energy storage battery according to the on-site conditions, which is equivalent to a DC-coupled energy storage unit. In this way, the electricity generated by the photovoltaic module will not be discarded under different weather conditions.

[0038] A unidirectional diode is installed on the cable connecting the photovoltaic module to the energy storage DC / DC converter to prevent the energy storage system from reverse charging the photovoltaic module.

[0039] At the same time, the DC / DC converter has a built-in circuit breaker, which makes it easier to control.

[0040] 1. Cost comparison

[0041] The wiring method of the present invention includes a DC / DC converter and a switch;

[0042] The prior art wiring methods include grid-connected inverters, bidirectional inverters and distribution cabinets;

[0043] From the cost point of view, DC / DC converters are cheaper than grid-connected inverters, and switches are cheaper than distribution cabinets.

[0044] Therefore, the wiring method of the present invention has a lower cost than the wiring method of the prior art.

[0045] 2. Efficiency comparison

[0046] If there are more cloudy days and the strong radiation time at noon is shorter, it is better to use the wiring method of the present invention;

[0047] Photovoltaic modules store electricity in batteries through DC / DC converters, with an efficiency of over 95%;

[0048] If the existing wiring method is used, photovoltaic power must first be converted into AC power through an inverter, then converted into DC power through a bidirectional converter, and then charged to the energy storage unit, and the efficiency will drop to about 90%.

[0049] In one embodiment, weak light energy storage is used when the photovoltaic system is running on cloudy days or in the early morning when the light is weak. The electricity generated by the photovoltaic modules is boosted through a cable through a DC / DC converter to charge the energy storage battery.

[0050] In one embodiment, the excess energy storage is used when the light is normal, and the electricity generated by the photovoltaic module is used to directly charge the energy storage battery according to the on-site conditions.

[0051] The present invention provides a method for increasing the power generation of a photovoltaic power station, using the above-mentioned system for increasing the power generation of a photovoltaic power station.

[0052] When it is cloudy or the light is weak in the early morning, close the inverter branch circuit breaker, the first circuit breaker of the energy storage branch, and the second circuit breaker of the energy storage branch, open the built-in circuit breaker of the DC / DC converter, and the electricity generated by the photovoltaic module is boosted through the cable and the DC / DC converter to charge the energy storage battery;

[0053] When the sunlight is normal, open the inverter branch circuit breaker, close the first circuit breaker of the energy storage branch and the second circuit breaker of the energy storage branch, and the electricity generated by the photovoltaic module is connected to the grid through the inverter or charged to the energy storage system from the inverter AC measurement. At the same time, open or close the built-in circuit breaker of the DC / DC converter according to the on-site situation to select whether to directly charge the energy storage battery;

[0054] When the energy storage battery is discharged, the first circuit breaker of the energy storage branch and the second circuit breaker of the energy storage branch are opened, and the electricity generated by the energy storage battery is connected to the power grid through the DC / AC converter and the booster.

[0055] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for increasing the power generation of a photovoltaic power station. It is characterized in that include: Inverter branch and energy storage branch; The inverter branch includes: the photovoltaic components are connected to the power grid in sequence through the inverter and the inverter branch circuit breaker; The energy storage branch includes: a photovoltaic module connected to an energy storage battery through a diode and a DC / DC converter in sequence; The energy storage battery system is connected to the power grid through the DC / AC converter, the first circuit breaker of the energy storage branch, the booster and the second circuit breaker of the energy storage branch in sequence; Among them, photovoltaic modules are used for photovoltaic power generation; energy storage batteries are used for weak light energy storage or excess energy storage; DC / DC converters have built-in circuit breakers; The power generation direction of the photovoltaic module is selected through the inverter branch circuit breaker, the built-in circuit breaker of the DC / DC converter, the first circuit breaker of the energy storage branch and the second circuit breaker of the energy storage branch.

2. A system for increasing the power generation of a photovoltaic power station according to claim 1, It is characterized in that Weak light energy storage is used when the photovoltaic system is running on cloudy days or in the early morning when the light is weak. The electricity generated by the photovoltaic panels is boosted through cables and DC / DC converters to charge the energy storage battery.

3. A system for increasing the power generation of a photovoltaic power station according to claim 1, It is characterized in that Excess energy storage is used when the sunlight is normal. The electricity generated by the photovoltaic panels is used to directly charge the energy storage battery according to the on-site conditions.

4. A method for increasing the power generation of a photovoltaic power station. It is characterized in that A system for increasing the power generation of a photovoltaic power station according to any one of claims 1 to 3, When it is cloudy or the light is weak in the early morning, close the inverter branch circuit breaker, the first circuit breaker of the energy storage branch, and the second circuit breaker of the energy storage branch, open the built-in circuit breaker of the DC / DC converter, and the electricity generated by the photovoltaic module is boosted through the cable and the DC / DC converter to charge the energy storage battery; When the sunlight is normal, open the inverter branch circuit breaker, close the first circuit breaker of the energy storage branch and the second circuit breaker of the energy storage branch, and the electricity generated by the photovoltaic module is connected to the grid through the inverter or charged to the energy storage system from the inverter AC measurement. At the same time, open or close the built-in circuit breaker of the DC / DC converter according to the on-site situation to select whether to directly charge the energy storage battery; When the energy storage battery is discharged, the first circuit breaker of the energy storage branch and the second circuit breaker of the energy storage branch are opened, and the electricity generated by the energy storage battery is connected to the power grid through the DC / AC converter and the booster.

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