A distribution transformer based on photovoltaic back-feeding loss suppression

Abstract

This invention discloses a distribution transformer for suppressing losses based on photovoltaic back-feedback, comprising: a transformer body; an oil conservator fixed to the upper surface edge of the transformer body by a bracket; an on-load tap changer disposed on one end face of the transformer body; a heat sink fixed to the side wall of the transformer body; and a current detection component fixed to one end of the transformer body to detect reverse current at the tap of the transformer body. By incorporating an air duct, a connecting pipe, and a drying chamber, this invention facilitates the use of the transformer body's own heat to pre-heat and dry the air, which is then condensed and liquefied in an extremely cold environment for further drying, reducing the frequency of maintenance and replacement of silica gel desiccant. The current detection component facilitates the identification of reverse current; when reverse current is detected, it triggers automatic voltage adjustment at the tap, reducing the voltage difference caused by photovoltaic back-feedback and the losses caused by power back-feedback to the high-voltage grid.

Description

Technical Field

[0001] This invention specifically relates to a distribution transformer based on photovoltaic reverse transmission to suppress losses. Background Technology

[0002] As the core equipment of the distribution network, the stable and efficient operation of the distribution transformer has a decisive impact on power quality and system losses. With the large-scale integration of distributed photovoltaic power generation, the distribution network is transforming from a traditional unidirectional radial network to a complex network with bidirectional power flow.

[0003] Under conditions of sufficient sunlight and light load, existing photovoltaic power generation may far exceed local absorption capacity, generating reverse current flowing from the user side to the low-voltage side of the transformer. This reverse current can raise the voltage, threatening the safety of electrical equipment on the user side. Furthermore, the long transmission path of electrical energy from the low-voltage side to the high-voltage grid via the transformer also causes energy loss. In addition, when distribution transformers are installed and used in humid environments, the silica gel desiccant in traditional oil-filled tank breathers is prone to saturation and failure, requiring frequent replacement to maintain the dryness of the internal insulating oil. Maintenance in high-temperature and high-humidity environments involves a large amount of manual labor and high costs, and does not effectively utilize the waste heat generated by the transformer itself during operation for dehumidification optimization. Therefore, we propose a distribution transformer based on photovoltaic reverse transmission to suppress losses. Summary of the Invention

[0004] The purpose of this invention is to provide a distribution transformer based on photovoltaic reverse transmission to suppress losses, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a distribution transformer based on photovoltaic reverse transmission to suppress losses, comprising:

[0006] Transformer body;

[0007] The oil conservator is fixed to the edge of the upper surface of the transformer body by a bracket;

[0008] An on-load tap changer is disposed on one end face of the transformer body;

[0009] A heat sink is fixed to the side wall of the transformer body;

[0010] A current detection component is fixed to one end of the transformer body to detect the reverse current at the tap changer of the voltage regulating winding inside the transformer body, and the current detection component is connected to the on-load tap changer through a wire.

[0011] An air duct is disposed inside the heat sink, and one end of the air duct has an air inlet, while the other end of the air duct is connected to a drying component for condensing and dehumidifying hot air.

[0012] A drying chamber is detachably installed on one end face of the oil tank, and the drying chamber is connected to the drying assembly. The drying chamber has a connecting pipe that is connected to the oil tank.

[0013] The drying assembly includes an outer cylinder, an inner cylinder, and an air cavity. The lower end of the outer cylinder extends inward and upward to form an inner cylinder, and an air guide pipe is fixed at the upper end of the inner cylinder, which extends out from the inside of the drying chamber. An air cavity communicating with the inside of the drying chamber is formed between the inner cylinder and the outer cylinder, and a one-way valve for draining liquid is provided at the bottom of the inner side of the air cavity.

[0014] The outer cylinder has a connection hole on one side wall that connects to the air duct, and the inner cylinder has an air guide plate on the outer wall that corresponds to the connection hole.

[0015] Preferably, the drying chamber is filled with a desiccant.

[0016] Preferably, the air duct has an inclined structure, and the inner wall of the air duct has strips to increase the contact area with air.

[0017] Preferably, the drying component has a ventilation slot on its inner side, and a semiconductor cooling chip is fixed to the inner wall of the ventilation slot.

[0018] Preferably, a filter screen is provided at the top of the air cavity corresponding to the drying chamber.

[0019] Preferably, the air guide plate is U-shaped.

[0020] Preferably, the current detection component includes a current detector, which is connected to the voltage regulating winding connector inside the transformer body via a wire.

[0021] Preferably, the current detection component further includes a power direction relay and a processor. The power direction relay and the processor are arranged side by side, and the input terminal of the power direction relay is electrically connected to the voltage regulating winding connector of the transformer body through another wire, and the output terminal of the power direction relay is connected to the processor.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] This invention, by incorporating an air duct, connecting pipe, and drying chamber, avoids the need for frequent silica gel replacement and maintenance, which is required in high-humidity environments when using traditional methods that rely solely on silica gel for dehumidification and drying. This device utilizes the transformer's own heat to pre-heat the air for simple drying, followed by condensation and cooling in an extremely cold environment, significantly improving air dryness. The cooled air also enhances the cooling effect on the hydraulic oil in the oil tank, reducing the frequency of silica gel desiccant replacement and lowering maintenance labor and material costs. Furthermore, the inclusion of a current detection component facilitates the identification of reverse current. When reverse current is detected, it triggers automatic voltage adjustment at the tap changer, reducing voltage differences caused by photovoltaic backfeed and losses from power backfeeding to the high-voltage grid. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the present invention;

[0025] Figure 2 This is a schematic diagram of the air duct installation structure of the present invention;

[0026] Figure 3 This is a schematic diagram of the drying component structure of the present invention;

[0027] Figure 4 This is a cross-sectional view of the drying assembly of the present invention;

[0028] Figure 5 This is a schematic diagram of the drying chamber structure of the present invention;

[0029] Figure 6 This is a schematic diagram of the air guide plate structure of the present invention;

[0030] Figure 7 This is a schematic diagram of the current detection component structure of the present invention.

[0031] In the diagram: 1. Transformer body; 2. Heat sink; 4. Oil conservator; 5. High-voltage bushing; 6. Low-voltage bushing; 7. Current detection assembly; 701. Current detector; 702. Power direction relay; 703. Processor; 8. On-load tap changer; 9. Air duct; 10. Drying assembly; 101. Outer cylinder; 102. Inner cylinder; 103. Air cavity; 104. Air guide plate; 11. Connecting pipe; 12. Drying chamber; 13. Check valve; 14. Ventilation slot; 15. Connection hole; 16. Filter screen; 17. Semiconductor cooling chip. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Please see Figures 1-7 This invention provides a technical solution: a distribution transformer based on photovoltaic reverse transmission to suppress losses, comprising:

[0034] Transformer body 1, with high-voltage bushing 5 and low-voltage bushing 6 arranged side by side on the upper surface of transformer body 1;

[0035] Oil conservator 4 is fixed to the edge of the upper surface of transformer body 1 by a bracket;

[0036] An on-load tap changer 8 is installed on one end face of the transformer body 1;

[0037] Heat sink 2 is fixed to the side wall of transformer body 1;

[0038] The current detection component 7 is fixed at one end of the transformer body 1 to detect the reverse current at the tap changer of the voltage regulating winding inside the transformer body 1. The current detection component 7 is connected to the on-load tap changer 8 through a wire, so that by integrating the current detection component 7 and cooperating with the on-load tap changer of the transformer body 1, an adaptive voltage control closed loop for photovoltaic reverse power flow is constructed, which suppresses the voltage limit of the transformer area from the source and reduces the reverse transmission loss.

[0039] An air duct 9 is located inside the heat sink 2, and one end of the air duct 9 has an air inlet, while the other end of the air duct 9 is connected to a drying component 10 for condensing and dehumidifying hot air.

[0040] The drying chamber 12 is detachably installed on one end face of the oil conservator 4, and the drying chamber 12 is connected to the drying assembly 10. The drying chamber 12 has a connecting pipe 11 that is connected to the oil conservator 4.

[0041] By using innovative breathing dehumidification, combining the transformer's own waste heat with active cooling, efficient and low-maintenance internal air drying is achieved, significantly improving the transformer's operational reliability and lifespan in harsh humidity environments, and greatly reducing the inconvenience of frequently replacing the silica gel desiccant in the transformer breather.

[0042] Preferably, the drying chamber 12 is filled with a desiccant;

[0043] The preferred desiccant is silica gel, molecular sieve, or anhydrous calcium chloride, so that the air can be dried again after condensation dehumidification, ensuring a good drying effect for the air entering the oil reservoir;

[0044] The drying assembly 10 includes an outer cylinder 101, an inner cylinder 102, and an air cavity 103. The lower end of the outer cylinder 101 extends inward and upward to form the inner cylinder 102, and the upper end of the inner cylinder 102 is fixed with an air guide pipe that passes through the inside of the drying chamber 12. An air cavity 103 communicating with the inside of the drying chamber 12 is formed between the inner cylinder 102 and the outer cylinder 101. A one-way valve 13 for draining liquid is provided at the bottom of the inner side of the air cavity 103.

[0045] This facilitates the formation of a stable airflow channel, ensuring sufficient contact time and area between the air and the relatively cool inner wall of the inner cylinder 102, making the condensation process more thorough and efficient, and ensuring the drying effect on the air;

[0046] The outer cylinder 101 has a connection hole 15 on one side wall that communicates with the air duct 9, and the inner cylinder 102 has an air guide plate 104 on the outer wall that corresponds to the connection hole 15.

[0047] This facilitates the guidance of hot air flow, prolongs air residence time, increases the contact area with the semiconductor cooling chip 17 at different positions, and ensures condensation efficiency.

[0048] Preferably, the air duct 9 has an inclined structure, and the inner wall of the air duct 9 has strips to increase the contact area with air;

[0049] The inclined structure of the air duct facilitates the extension of the air travel length along the air duct 9, which is beneficial for heating and drying. The duct also facilitates the discharge of condensate and prevents its accumulation. In addition, a glass plate or semiconductor cooling chip can be installed on the upper inner side of the air duct 9 to condense the air as it moves along the air duct 9, remove moisture from the air, and dry it. The strip design of the inner wall increases the heat exchange area and improves the efficiency of using waste heat to preheat the air.

[0050] Preferably, a ventilation groove 14 is provided on the inner side of the drying component 10, and a semiconductor cooling chip 17 is fixed on the inner wall of the ventilation groove 14.

[0051] The ventilation slot 14 allows natural air to flow inside, thereby cooling the inner cylinder 102 in conjunction with the thermoelectric cooler 17. The natural airflow also helps to reduce the heat generated by the thermoelectric cooler 17 itself.

[0052] Preferably, a filter screen 16 is provided at the top of the air cavity 103 corresponding to the drying chamber 12;

[0053] It can effectively block dust particles in the air from being carried into the oil pillow, preventing oil and desiccant contamination and keeping the entire breathing passage clean.

[0054] Preferably, the air guide plate 104 is U-shaped.

[0055] Preferably, the current detection assembly 7 includes a current detector 701, which is connected to the voltage regulating winding connector inside the transformer body 1 via a wire.

[0056] By directly monitoring the tap current with a current detector, the most direct and reliable electrical quantity basis is provided for judging photovoltaic backfeed.

[0057] During use, the current detector 701 is used to detect the current on the low-voltage side of the transformer body 1 in real time. When it is determined that a reverse current has occurred and the current voltage of the transformer area has been continuously exceeding the threshold for a period of time, the existing on-load tap changer 8 is used to adjust the tap to reduce the voltage to the normal range.

[0058] Preferably, the current detection component 7 further includes a power direction relay 702 and a processor 703. The power direction relay 702 and the processor 703 are arranged side by side, and the input terminal of the power direction relay 702 is electrically connected to the voltage regulating winding connector of the transformer body 1 through another wire, and the output terminal of the power direction relay 702 is connected to the processor 703.

[0059] During normal voltage reduction periods, if the current detection component 7 does not detect reverse current, the power direction can be determined by accurately measuring the phase angle between voltage and current through the power direction relay 702. If the current lags behind the voltage by an angle exceeding a certain range, it may mean that the current detection component 7 is faulty. The processor 703 processes the data to send an alarm signal or transmits a signal to the on-load tap changer 8 to perform voltage reduction.

[0060] The working principle and usage process of this invention are as follows: During use, the current detector 701 monitors the output voltage of the transformer. When a reverse current is triggered and the voltage does exceed the threshold, a signal is transmitted to the on-load tap changer 8. The on-load tap changer 8 causes the tap to operate and reduce the voltage, thereby adjusting the output voltage of the transformer area and reducing the voltage difference caused by photovoltaic backfeed, which leads to excessive voltage and losses caused by power backfeed to the high-voltage grid.

[0061] When the hydraulic oil experiences a temperature change that causes the oil conservator 4 to "breathe," outside air flows into the air chamber 103 through the air duct 9. The air is heated by the heat radiated from the transformer body 1 and the heat sink 2. The hot airflow comes into contact with the cooler inner wall of the air chamber 103 and is quickly condensed into water droplets. These droplets are then discharged through the one-way valve 13 at the lower end of the air chamber 103. The hot airflow is dried and cooled, then flows into the drying chamber 12. After being dried again by the desiccant, it is introduced into the oil conservator 4 to maintain its dryness. This device greatly reduces the frequency of desiccant maintenance and replacement in humid installation environments, thus reducing maintenance costs.

[0062] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A distribution transformer based on photovoltaic reverse transmission to suppress losses, characterized in that, include: Transformer body (1); The oil conservator (4) is fixed to the edge of the upper surface of the transformer body (1) by a bracket; An on-load tap changer (8) is disposed on one end face of the transformer body (1); Heat sink (2) is fixed to the side wall of the transformer body (1); The current detection component (7) is fixed to one end of the transformer body (1) to detect the reverse current at the tap changer of the voltage regulating winding inside the transformer body (1), and the current detection component (7) is connected to the on-load tap changer (8) through a wire. An air duct (9) is provided inside the heat sink (2), and an air inlet is provided at one end of the air duct (9), and a drying component (10) for condensing and dehumidifying hot air is connected to the other end of the air duct (9). The drying chamber (12) is detachably installed on one end face of the oil tank (4), and the drying chamber (12) is connected to the drying assembly (10). The drying chamber (12) has a connecting pipe (11) connected to the oil tank (4). The drying assembly (10) includes an outer cylinder (101), an inner cylinder (102), and an air cavity (103). The lower end of the outer cylinder (101) extends inward and upward to form the inner cylinder (102), and the upper end of the inner cylinder (102) is fixed with an air guide pipe that passes through the inside of the drying chamber (12). An air cavity (103) communicating with the inside of the drying chamber (12) is formed between the inner cylinder (102) and the outer cylinder (101). A one-way valve (13) for draining liquid is provided at the bottom of the inner side of the air cavity (103). The outer cylinder (101) has a connection hole (15) on one side wall that communicates with the air duct (9), and the inner cylinder (102) has an air guide plate (104) on the outer wall that corresponds to the connection hole (15).

2. The distribution transformer based on photovoltaic reverse transmission to suppress losses according to claim 1, characterized in that: The drying chamber (12) is filled with desiccant.

3. A distribution transformer based on photovoltaic reverse transmission to suppress losses according to claim 1, characterized in that: The air duct (9) has an inclined structure, and the inner wall of the air duct (9) has strips to increase the contact area with air.

4. A distribution transformer based on photovoltaic reverse transmission to suppress losses according to claim 1, characterized in that: The drying component (10) has a ventilation slot (14) on its inner side, and a semiconductor cooling chip (17) is fixed on the inner wall of the ventilation slot (14).

5. A distribution transformer based on photovoltaic reverse transmission to suppress losses according to claim 1, characterized in that: A filter screen (16) is provided at the top of the air cavity (103) corresponding to the drying chamber (12).

6. A distribution transformer based on photovoltaic reverse transmission to suppress losses according to claim 1, characterized in that: The air guide plate (104) is U-shaped.

7. A distribution transformer based on photovoltaic reverse transmission to suppress losses according to claim 1, characterized in that: The current detection assembly (7) includes a current detector (701), which is connected to the voltage regulating winding connector inside the transformer body (1) via a wire.

8. A distribution transformer based on photovoltaic reverse transmission to suppress losses according to claim 7, characterized in that: The current detection component (7) also includes a power direction relay (702) and a processor (703). The power direction relay (702) and the processor (703) are arranged side by side. The input terminal of the power direction relay (702) is electrically connected to the voltage regulating winding connector of the transformer body (1) through another wire. The output terminal of the power direction relay (702) is connected to the processor (703).

Images