Photovoltaic energy on-line energy storage anti-reflux device

Abstract

The invention discloses a photovoltaic energy grid-connected energy storage anti-reflux device, which is characterized in that the power generated by a photovoltaic panel (7) is preferentially consumed by a load (11), and when the load (11) is not turned on or the use amount is small, redundant power is automatically and reversely transmitted to a power grid (6), so that the function of self-generation and self-use of the redundant power for grid-connected is realized. The data acquisition controller (1) analyzes the photovoltaic electric energy consumed by the load (11) and the real-time change of the electric energy of the power grid according to the peak time period and the peak time period, adjusts the output power of the energy storage inverter (5) in real time so as to achieve the countercurrent prevention function, and ensures that the reverse on-grid electric quantity is the photovoltaic power generation quantity. Finally, the purpose of reducing the electricity consumption cost by using the surplus electricity for photovoltaic power generation to surf the Internet and charging and discharging the stored energy in different periods is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of power transmission and metering of photovoltaic energy storage stations, and in particular to a photovoltaic energy storage backflow prevention device. Background Art

[0002] Photovoltaic power generation and battery energy storage have developed rapidly in my country in recent years. In order to reduce electricity costs, many companies have invested heavily in building large-scale photovoltaic power stations to meet their production needs. When there is surplus electricity generated by photovoltaics, it is sent back to the power grid. The State Grid measures and purchases the reverse input electricity to achieve self-generation and self-use. Surplus electricity is connected to the grid. In order to reduce electricity costs, many companies have also invested heavily in building large-scale battery energy storage power stations. They use the price difference between peak, flat and valley periods to store the power of the State Grid by charging batteries during flat and valley periods, and discharge the stored electricity through inverters during peak and peak periods for production loads, so as to save electricity costs. They are also equipped with anti-reverse power transmission equipment to prevent power from being sent back to the power grid.

[0003] During the operation of a photovoltaic power station that generates electricity for its own use and connects the surplus electricity to the grid, the output power of the inverter depends on the intensity of sunlight. The output power changes with the increase or decrease of the light intensity. When the load demand power exceeds the generated power, the power grid automatically makes up for the shortfall. When the load power is less than the generated power, the excess electric energy is reversely fed into the grid, achieving self-generation and self-consumption of surplus electricity connected to the grid to ensure maximum investment benefits.

[0004] During the operation of the battery energy storage power station, the stored electric energy is not allowed to flow back to the grid, and an anti-backflow device must be equipped to prevent the occurrence of backflow. The working principle of the anti-backflow device is: real-time monitoring of the load power consumption data and using this power data as a basis to control the output power of the energy storage inverter, and its output power is always kept equal to or slightly less than the power required by the load to prevent the occurrence of backflow.

[0005] When some enterprises are equipped with both photovoltaic power stations and battery energy storage stations and connected to the grid for power transmission, the surplus electricity of the photovoltaic power stations is allowed to be fed back to the grid and generate income, but the electricity output by the battery is not allowed to be fed back into the grid. This is because the positive and reverse electricity meters cannot distinguish whether the reverse electricity comes from the surplus electricity of the photovoltaic power station or the electricity of the energy storage station. The reverse electricity generated by the enterprise cannot be settled. Enterprises equipped with photovoltaic power stations and battery energy storage stations can only send the reverse photovoltaic electricity to the grid for nothing. Summary of the invention

[0006] In response to the above problems: the present invention provides a photovoltaic grid-connected energy storage and anti-backflow device that can effectively solve the above defects.

[0007] In order to achieve the above objectives, the present invention provides the following solutions: a photovoltaic grid-connected energy storage and anti-backflow device, the system is mainly composed of a data acquisition control system and a power distribution system.

[0008] The data acquisition control system comprises: a data acquisition controller (1), a forward and reverse electric energy meter (2), a load current transformer (3), an energy storage current transformer (4), and an energy storage inverter (5).

[0009] The power distribution system includes: a power grid (6), a photovoltaic panel (7), a photovoltaic inverter (8), an energy storage battery (9), a load transformer (10), a load (11), a photovoltaic step-up transformer (12), and an energy storage step-up transformer (13). BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is the high voltage side grid connection diagram of the photovoltaic energy storage of the present invention.

[0011] Figure 2 This is the low-voltage side grid connection diagram of the photovoltaic energy storage of the present invention.

[0012] Figure 3 This is the low-voltage side grid-connected photovoltaic energy storage high-voltage side grid-connected diagram of the present invention.

[0013] Figure 4 This is the grid-connected diagram of the low-voltage side of the energy storage and the high-voltage side of the photovoltaic grid-connected according to the present invention. Implementation

[0014] Combine the following Figure 1 , Figure 2 , Figure 3 , Figure 4 The specific implementation of the present invention is described: 1. The data acquisition controller (1) is provided with a signal input terminal, a control output terminal and a power input terminal, which are respectively connected to a forward and reverse electric energy meter (2), a load current transformer (3), an energy storage current transformer (4) and an energy storage inverter (5).

[0015] 2. In the power distribution system, the DC output terminal of the photovoltaic panel (7) is connected to the DC input terminal of the photovoltaic inverter (8); the low-voltage side of the photovoltaic step-up transformer (12) is connected to the AC output terminal of the photovoltaic inverter (8), and the high-voltage side is connected to the busbar of the power grid (6); the DC output terminal of the energy storage battery (9) is connected to the DC input terminal of the energy storage inverter (5); the low-voltage side of the energy storage step-up transformer (13) is connected to the AC output terminal of the energy storage inverter (5), and the high-voltage side is connected to the busbar of the power grid (6); the high-voltage side of the load transformer (10) is connected to the busbar of the power grid (6), and the low-voltage side is connected to the load (11).

[0016] The following is a detailed and complete explanation of the technical solutions and logical relationships in the embodiments of the present invention in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Other embodiments obtained by ordinary technicians in this field without making creative improvements all belong to the scope of protection of the present invention. The implementation of these functions is explained one by one in conjunction with the above drawings.

[0017] After the sun rises, the photovoltaic control system [the photovoltaic control system and the data acquisition controller have the function of wireless or wired data communication] detects that various parameters meet the power generation requirements, and then automatically generates electricity at the highest efficiency until the sun sets and the power generation conditions are no longer met. The generated electricity is used first for the internal load of the enterprise. If the power required by the load is less than the power generation power, the excess electricity is automatically connected to the Internet to realize the function of self-generation and self-use and surplus power connected to the Internet.

[0018] The energy storage side of this photovoltaic energy storage power station is only allowed to charge during flat and valley periods, and is prohibited from discharging; during peak and peak periods, only discharging is allowed, and charging is prohibited. The purpose of reducing electricity costs is achieved through charging and discharging with the price difference between flat and valley periods and peak and peak periods; during the discharge process of the energy storage side, electricity is only allowed to be used for self-use, and it is prohibited to flow back into the grid. The output power must be automatically adjusted in real time to ensure that all the output electricity is used for self-use.

[0019] First attach Figure 1 The principle is explained with the wiring topology diagram: This topology diagram is mainly suitable for occasions where the photovoltaic side and the energy storage side are far away from the load and need to be stepped up to transmit electric energy. First, the direct current generated by the photovoltaic panel (7) is inverted by the photovoltaic inverter (8) and stepped up by the photovoltaic step-up transformer (12) before being sent to the grid-connected busbar, and is preferentially stepped down by the load transformer (10) before being provided to the load (11) for consumption. When the load (11) is not turned on or the power consumption is low, the excess power is automatically sent back to the grid (6), realizing the function of self-generation and self-use and surfing the surplus power online.

[0020] At the same time, the data acquisition controller (1) receives and analyzes the data fed back by the forward and reverse electric energy meters (2) and the load current transformer (3). When the current transformer (3) detects that there is a forward current, that is, the power grid (6) outputs electric energy to the load (11), it first determines whether this time period is a peak time period. When it is a peak time period, the energy storage inverter (5) is started to invert the electric energy of the energy storage battery (9) to the energy storage boost transformer (13) for boosting and then sending it to the grid-connected bus for consumption by the load (11). As the output power of the energy storage inverter (5) increases, the output power of the power grid (6) gradually decreases until the forward current of the current transformer (3) approaches zero, that is, when the power grid (6) has no power output to the load (11), the output power of the energy storage inverter (5) will remain unchanged; when the current transformer (3) detects a small reverse current, [the small reverse current at this time is too small to drive the forward and reverse power meters (2) to reverse measurement], the output power of the energy storage inverter (5) decreases accordingly until the reverse current is zero and the output power stops decreasing, so as to ensure that no reverse power occurs.

[0021] After analyzing the real-time changes of the photovoltaic power and grid power consumed by the load (11) according to the peak and peak periods, the data acquisition controller (1) adjusts the output power of the energy storage inverter (5) in real time to achieve the function of preventing reverse flow and ensure that the reverse grid-connected power is the power generated by the photovoltaic power generation, and finally realizes the purpose of reducing the power cost by grid-connecting the surplus power of photovoltaic power generation for self-use and charging and discharging the energy storage in different time periods.

[0022] Attached Figure 2 The wiring topology diagram is mainly suitable for situations where the photovoltaic side and the energy storage side are close to the load and connected to the grid through low voltage. The working principle is similar to the attached Figure 1 The working principle is the same.

[0023] Attached Figure 3 The wiring topology diagram is mainly suitable for situations where the photovoltaic side is close to the load and connected to the grid through low voltage, and the energy storage side is far from the load and connected to the grid through a step-up transformer. The working principle is similar to the attached Figure 1 The working principle is the same.

[0024] Attached Figure 4 The wiring topology diagram is mainly suitable for situations where the energy storage side is close to the load and connected to the grid through low voltage, and the photovoltaic side is far from the load and connected to the grid through a step-up transformer. The working principle is similar to the attached Figure 1 The working principle is the same.

Claims

1. A photovoltaic energy storage and backflow prevention device, characterized in that The data acquisition control system comprises: a data acquisition controller (1), a forward and reverse electric energy meter (2), a load current transformer (3), an energy storage current transformer (4), and an energy storage inverter (5) which are connected to each other.

2. A photovoltaic energy storage and backflow prevention device according to claim 1, characterized in that: The electricity generated by the photovoltaic panel (7) is consumed by the load (11) first. When the load (11) is not turned on or the consumption is small, the excess electricity is automatically fed back to the power grid (6), thereby realizing the function of self-generation and self-use and the access to the grid of surplus electricity.

3. A photovoltaic energy storage and backflow prevention device according to claim 1, characterized in that: When the data acquisition controller (1) receives the forward current detected by the current transformer (3), it first determines whether this period is a peak period. When it is a peak period, it starts the energy storage inverter (5) to output for the load (11). As the output power of the energy storage inverter (5) increases, the output power of the power grid (6) gradually decreases until the forward current of the current transformer (3) approaches zero, that is, the power grid (6) has no power output to the load (11), and the output power of the energy storage inverter (5) remains unchanged; when the current transformer (3) detects a small reverse current, [the small reverse current at this time is too small to drive the forward and reverse electric energy meter (2) to reverse measurement], the output power of the energy storage inverter (5) decreases accordingly until the reverse current is zero and the output power stops decreasing, so as to ensure that no reverse electric energy occurs.

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