Three-phase load balance electric meter box capable of automatically pre-judging and selecting optimal operation mode
By using a two-phase switching method between microprocessor control relay and current transformer in the meter box, the problem of three-phase load imbalance is solved, the optimal three-phase balance state of the meter box is achieved, and the power utilization and voltage are improved quality.
Patent Information
- Application Number
- CN202411136198.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-19
- Publication Date
- 2024-12-31
AI Technical Summary
In the existing low-voltage power supply systems, the three-phase load imbalance leads to insufficient output of the transformer, poor voltage quality, increased copper and iron loss, and it is difficult to maintain three-phase balance, affecting the operating efficiency of the meter box and the user voltage quality.
Design a three-phase load balanced meter box that automatically predicts and selects the optimal operating mode, adopts a microprocessor to control the relay and current transformer, and achieves three-phase balance through two-phase switching method, reducing the number of actuators and CPU computing burden, and avoiding Phase-to-phase short circuit phenomenon improves switching speed.
It realizes that the meter box always operates in the best three-phase balance state, reduces the number of switching times and the risks of traditional protection circuits, improves the power utilization rate and voltage quality, and meets the balance needs of low-voltage systems.
Smart Images
Figure CN119231578A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of power supply, and in particular relates to a three-phase load balancing meter box capable of automatically pre-judging and selecting an optimal operation mode. Background Art
[0002] At present, most rural areas and some urban areas use low-voltage power supply with public distribution transformers as the core. Rural public distribution stations refer to a power supply method in which a single or multiple distribution transformers provide power supply to multiple users. Among them, most of them are single three-phase transformers that provide single-phase 220-volt living power supply for multiple users with power loads less than 3 kilowatts. This type of low-voltage power supply system generally has a small single-user load, large real-time changes, a large number of users, a wide distribution range, and the distribution of three-phase loads is difficult to control. This causes an unbalanced three-phase load on the distribution transformer and large changes in the voltage at the user's end. The main hazards caused by the unbalanced three-phase load of the distribution transformer are:
[0003] 1. The transformer output is insufficient and cannot reach full capacity power supply, wasting resources; causing transformer overheating and core saturation, affecting the life of the transformer.
[0004] 2. The voltage quality of users does not meet the requirements.
[0005] 3. The copper and iron losses of the transformer increase, the low-voltage line losses increase, and a large amount of electrical energy is wasted.
[0006] The existing public low-voltage distribution substations mostly adopt the power supply method of user electric energy meters installed in the meter box. Because the user's living power load is mostly single-phase power supply, the meter box also adopts single-phase incoming line or divided into single phase. The single-phase incoming line method does not have the problem of three-phase balanced power supply as the meter box. It can only rely on multiple meter boxes to supply power from different phases to balance the single-phase load of the low-voltage line and the transformer, which is relatively difficult. The three-phase incoming line method is difficult to maintain three-phase balance due to the constant changes in individual user loads. Summary of the invention
[0007] In view of the above-mentioned technical problems, the present invention proposes a three-phase load balancing meter box which has a reasonable design, a simple structure, is easy to process and can make the meter box always operate in the optimal three-phase balanced state. When multiple meter boxes use this device at the same time, the entire low-voltage system can operate in the optimal three-phase balanced state, thereby achieving the purpose of protecting the circuit, reducing the danger, and effectively meeting the use requirements and automatically predicting and selecting the optimal operating mode.
[0008] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is a three-phase load balancing meter box that automatically pre-judges and selects the optimal operating mode, including an electric meter box, a leakage circuit breaker is arranged in the electric meter box, and the leakage circuit breaker is externally connected to a three-phase four-wire power supply A, B, C and O, and a phase selection controller for controlling the phase of the user's electric meter is arranged on one side of the leakage circuit breaker, and an electric energy meter B1-B9 is arranged on one side of the phase selection controller, and the phase selection controller includes relays J1-J9, current transformers CT1-CT9, rectifier filters, analog-to-digital converters and phase control components, wherein every three relays are sequentially set up as a group, and the normally closed contacts of the three groups of relays are connected in sequence. The points are connected to the A, B, and C phases of the three-phase four-wire power supply in sequence, the normally open contacts of the three groups of relays are connected to the B, C, and A phases of the three-phase four-wire power supply in sequence, a plurality of rectifier filters are respectively connected to the current transformers CT1-CT9 correspondingly, and one side of the rectifier filter is connected to the analog-to-digital converter, the phase control component includes a microprocessor for receiving the analog-to-digital converter signal, one side of the microprocessor is provided with an input and output signal terminal, one side of the input and output signal terminal is provided with a photoelectric coupler, wherein nine photoelectric couplers are provided and are connected to the coil access ports of relays J1-J9 in sequence, and current limiting resistors are provided on both sides of the photoelectric coupler.
[0009] Preferably, the output ends of the relays J1-J9 are connected to the input ends of the current transformers CT1-CT9 in sequence, and the output ends of the current transformers CT1-CT9 are connected to the live wire interfaces of the electric energy meters B1-B9 in sequence.
[0010] Preferably, the rectifier filter is connected in series with the current transformer, and the output end thereof is connected in turn with the input end of the analog-to-digital converter.
[0011] Preferably, an outlet terminal is provided on one side of the electric energy meter B1-B9, wherein the live wire port and the neutral wire port of the electric energy meter B1-B9 are respectively connected to the outlet terminal, and the neutral wire interface of the electric energy meter B1-B9 is connected to the O phase of the three-phase four-wire power supply.
[0012] Compared with the prior art, the advantages and positive effects of the present invention are:
[0013] 1. The present invention provides a three-phase load balancing meter box that automatically predicts and selects the optimal operating mode. The optimal operating mode can be predicted in advance, avoiding the blindness of other adjustment modes; the established microprocessor is used to evaluate all possible operating modes with the help of its high-speed calculation, and the optimal mode is selected for input. At the same time, the adjustment reference value can be set to avoid frequent adjustments. In addition, the operation phase can be selected based on comprehensive evaluation such as historical data, which significantly reduces the number of switching times; the switching method between two phases reduces the number of actuators and the CPU computing burden; the dual-node relay avoids the phase-to-phase short circuit caused by asynchronous action during the switching process, reduces the traditional protection circuit, and improves the switching speed; on the basis of the original three-phase incoming line meter box, this device is equipped with a set of devices for controlling the phase of the user's meter input, and automatically selects an optimized input mode by controlling the advanced algorithm of the microprocessor, so as to achieve the purpose of automatically balancing the three-phase load. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 creative work.
[0015] Figure 1 A schematic diagram of the structure of the meter box connection for the existing single-phase incoming line;
[0016] Figure 2 A schematic diagram of the structure of the meter box connection for the existing three-phase incoming line;
[0017] Figure 3 A schematic diagram of the structure of the three-phase incoming line meter box connection provided by the present invention;
[0018] Figure 4 This is a structural schematic diagram of the automatic optimal connection of the three-phase load balancing meter box provided by the present invention;
[0019] Figure 5 The binary number composed of the relay position and the corresponding current meter of each phase;
[0020] In the above figures, 1. leakage circuit breaker; 2. electric energy meter; 3. rectifier filter; 4. relay; 5. current transformer; 6. output terminal; 7. photocoupler; 8. analog-to-digital converter; 9. microprocessor; 10. current limiting resistor; 11. coil; 12. normally closed contact; 13. normally open contact. DETAILED DESCRIPTION
[0021] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.
[0022] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments of the following disclosure.
[0023] Examples, such as Figure 1 to Figure 4As shown, a three-phase load balancing meter box that automatically predicts and selects the optimal operation mode includes a meter box. The meter box is an existing mature technology, which ensures the effective installation and establishment of each phase line and ensures that electricity is put into use by users. It is an indispensable part of the circuit system and can also play a good protective role for the lines, etc.; further, a leakage circuit breaker 1 is arranged in the meter box, and the leakage circuit breaker 1 is externally connected to a three-phase four-wire power supply A, B, C and O. The establishment of the above-mentioned equipment components is all existing conventional technical means, and the specific details are not repeated; this embodiment aims to solve the problem that the existing three-phase incoming line method is difficult to maintain three-phase due to the continuous change of individual user loads. Phase balance problem, specifically: one side of the leakage circuit breaker 1 is provided with a phase selection controller for controlling the phase of the user's electric meter, one side of the phase selection controller is provided with electric energy meters B1-B9, the phase selection controller includes relays J1-J9, current transformers CT1-CT9, rectifier filters 3, analog-to-digital converters 8 and phase control components, and the selected analog-to-digital converter 8 is an A / D converter. Further: every three relays 4 are sequentially set up as a group, and the normally closed contacts 12 of the three groups of relays 4 are sequentially connected to the A, B, and C phases of the three-phase four-wire power supply, and the normally open contacts 13 of the three groups of relays 4 are sequentially connected to the three The B, C, and A phases of the four-phase four-wire power supply are connected, specifically described as: According to the above, the electric energy meter B1-B3 can be switched between the A and B phases through the relay 4, B4-B6 can be switched between the B and C phases, and B7-B9 can be switched between the C and A phases. The reason for not choosing to switch between three phases is: First, the two-phase switching can achieve the selection of any phase can be put into N-3 user loads at most, and at least 0 loads, because the A, B, and C three phases are completely equal, so the combination generated by the two-phase switching already includes the most preferred way of three-phase balance; second, it can save the number of control components and save costs , Third: reduce the computing burden of the microprocessor 9 and improve the computing speed; multiple rectifier filters 3 are respectively connected to the current transformers CT1-CT9, and one side of the rectifier filter 3 is connected to the analog-to-digital converter 8, and the phase control component includes a microprocessor 9 for receiving the signal of the analog-to-digital converter 8, the microprocessor 9 is an ARM system, one side of the microprocessor 9 is provided with an input and output signal terminal, and one side of the input and output signal terminal is provided with a photoelectric coupler 7, wherein nine photoelectric couplers 7 are provided, and are sequentially connected to the coil 11 access ports of the relays J1-J9, and both sides of the photoelectric coupler 7 are provided with current limiting resistors 10;
[0024] In the above process: for the nine relays 4 set up, each relay 4 has two states: energized and released. The released state is defined as 0 and the energized state is defined as 1. Then, the states of the nine relays 4 can generate 512 combinations of [000000000-111111111], each combination corresponds to a binary number and [0-511] 512 decimal numbers. For details, see Figure 5 ; For the current transformer 5, rectifier filter 3 and analog-to-digital converter 8 set up after the relay 4, they can detect the real-time current value of each user and convert it into a digital quantity that can be processed by the microprocessor 9. The microprocessor 9 performs real-time calculation based on the collected data according to the combination of data labels [000000000-11111111] corresponding to the meter status of each phase connected to the user; by calculation, the current and the imbalance rate [(I maximum phase-I minimum phase) / I maximum phase], [absolute value of unbalanced current I maximum phase-I minimum phase] that can be generated by each combination at the sampling moment can be determined, and stored in the database table file together with the corresponding data labels and acquisition time; for the established microprocessor 9, it determines whether to switch according to the three-phase imbalance rate, the absolute value of the three-phase unbalanced current and the preset reference value generated by the current operating mode combination, and switches to the combination with the smallest three-phase imbalance rate. If there are multiple combinations with similar three-phase imbalance rates, the microprocessor 9 will refer to historical data and give priority to the operation mode with the most historical input times to reduce the number of switching times. The phase with the highest voltage in the three-phase system is generally the phase with the lowest load in the system. Therefore, the operation mode with large load in the high voltage phase can be given priority according to the current three-phase voltage value. In this way, the three-phase load of the entire low-voltage system can be balanced. Through the above adjustment, the meter box can always operate in the best three-phase balanced state. Using this device for multiple meter boxes at the same time can make the entire low-voltage system operate in the best three-phase balanced state; this device can predict the best operation mode in advance, avoiding the blindness of other adjustment methods; using the established microprocessor 9, with the help of its high-speed computing All possible operation modes are evaluated, and the best mode is selected for operation. At the same time, the adjustment reference value can be set to avoid frequent adjustments. In addition, the operation phase can be selected based on comprehensive evaluation such as historical data, which significantly reduces the number of switching times. The two-phase switching method reduces the number of actuators and the CPU computing burden. The dual-node relay 4 avoids the phase-to-phase short circuit caused by asynchronous action during the switching process, reduces the traditional protection circuit, and improves the switching speed. Based on the original three-phase incoming meter box, this device is equipped with a device for controlling the phase of the user's meter. By controlling the advanced algorithm of the microprocessor 9, an optimized operation mode is automatically selected to achieve the purpose of automatically balancing the three-phase load.
[0025] In order to ensure the connectivity of the circuit in the meter box and ensure the realization of the automatic balancing three-phase load function, the output ends of relays J1-J9 are connected to the input ends of current transformers CT1-CT9 in sequence, that is to say: multiple relays 4 are connected to current transformers 5 in order from small to large, ensuring the effective realization of current changes and providing convenient conditions for the subsequent transmission of signals to the analog-to-digital converter 8. The output ends of current transformers CT1-CT9 are connected to the live wire interfaces of energy meters B1-B9 in sequence, ensuring the normal realization of the switching actions of each energy meter 2, thereby realizing three-phase load balancing.
[0026] In order to effectively improve the performance and stability of the rectifier circuit, the rectifier filter 3 is connected in series with the current transformer 5, and its output end is connected to the input end of the analog-to-digital converter 8 in turn. The serial connection can increase the rated load of the transformer, and to a certain extent improve the output capacity of the transformer and the accuracy of the signal. In this way, the real-time current value of each user can be stably detected, and the value can be converted into a digital quantity that can be processed by the microprocessor 9, which effectively improves the accuracy of the value conversion process, ensures the effective operation of the subsequent phase control component, and provides a prerequisite for achieving the purpose of automatically balancing the three-phase load to meet the use requirements.
[0027] In order to further improve the rationality of the installation of the device, especially to ensure the output and detection of electric power resources in the meter box, an outlet terminal 6 is provided on one side of the electric energy meter B1-B9, wherein the live wire port and the neutral wire port of the electric energy meter B1-B9 are respectively connected to the outlet terminal 6, and the neutral wire interface of the electric energy meter B1-B9 is connected to the O phase of the three-phase four-wire power supply. The above connection method is the conventional connection method of the electric energy meter 2 in the prior art, which ensures that the electric energy meter 2 can be put into use by users and guarantees the use needs.
[0028] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.
Claims
1. A three-phase load balancing meter box that automatically pre-judges and selects the optimal operation mode, comprising a meter box, wherein a leakage circuit breaker is arranged in the meter box, and the leakage circuit breaker is externally connected to a three-phase four-wire power supply A, B, C and O, characterized in that: A phase selection controller for controlling the phase of the user's electric meter is arranged on one side of the leakage circuit breaker, and an electric energy meter B1-B9 is arranged on one side of the phase selection controller. The phase selection controller includes relays J1-J9, current transformers CT1-CT9, rectifier filters, analog-to-digital converters and phase control components, wherein each three relays are sequentially set up as a group, and the normally closed contacts of the three groups of relays are sequentially connected to the A, B, and C phases of the three-phase four-wire power supply, and the normally open contacts of the three groups of relays are sequentially connected to the B, C and A phases are connected, multiple rectifier filters are respectively connected to the current transformers CT1-CT9, and one side of the rectifier filter is connected to the analog-to-digital converter. The phase control component includes a microprocessor for receiving the analog-to-digital converter signal, one side of the microprocessor is provided with an input and output signal terminal, and one side of the input and output signal terminal is provided with a photoelectric coupler, wherein nine photoelectric couplers are provided and are connected to the coil access ports of relays J1-J9 in sequence, and current limiting resistors are provided on both sides of the photoelectric coupler.
2. The three-phase load balancing meter box for automatically predicting and selecting the optimal operation mode according to claim 1 is characterized in that: The output ends of the relays J1-J9 are connected to the input ends of the current transformers CT1-CT9 in sequence, and the output ends of the current transformers CT1-CT9 are connected to the live wire interfaces of the electric energy meters B1-B9 in sequence.
3. The three-phase load balancing meter box for automatically predicting and selecting the optimal operation mode according to claim 2 is characterized in that: The rectifier filter is connected in series with the current transformer, and the output end of the rectifier filter is connected in turn with the input end of the analog-to-digital converter.
4. The three-phase load balancing meter box for automatically predicting and selecting the optimal operation mode according to claim 3 is characterized in that: An outlet terminal is provided on one side of the electric energy meter B1-B9, wherein the live wire port and the neutral wire port of the electric energy meter B1-B9 are respectively connected to the outlet terminal, and the neutral wire interface of the electric energy meter B1-B9 is connected to the O phase of the three-phase four-wire power supply.