A phase commutation control method and a phase commutation control device

Abstract

The application relates to the technical field of commutation control, and discloses a commutation control method and a commutation control device, which comprise the following steps: judging whether to trigger commutation control according to the three-phase unbalance degree of a low-voltage transformer area; judging whether the real-time voltage value of a first phase is greater than the real-time voltage value of a second phase; if yes, controlling the control switch of the first phase and the second phase according to first commutation parameters to switch the power supply path to an auxiliary path of the first phase; if the real-time voltage value of the first phase is less than the real-time voltage value of the second phase, controlling the diode of the first phase and the second phase according to second commutation parameters to switch the power supply path to an auxiliary path of the second phase; and controlling the control switch and the diode of the first phase and the second phase according to the working parameters and the load control parameters of the second phase to switch the power supply path to a main path of the second phase. The application ensures the stability and safety of the commutation process, and effectively improves the power supply reliability and operation economy of the low-voltage transformer area.

Description

Technical Field

[0001] This invention relates to the field of commutation control technology, and in particular to a commutation control method and a commutation control device. Background Technology

[0002] Currently, commutation technology is used to address three-phase imbalance in low-voltage distribution transformer areas. Most existing commutation technologies employ traditional mechanical switches or some power electronic commutation devices. The main problem with these existing technologies is the instantaneous power interruption that occurs during the commutation process. Taking typical mechanical switch commutation as an example, it relies on mechanical contact switching, which creates a power supply gap, leading to a power interruption. This interruption not only interferes with the stable operation of sensitive loads such as computers and medical equipment, easily causing data loss and equipment failure, but also accelerates the aging of switching equipment due to the electric arc and inrush current impact during commutation, increasing the failure rate and maintenance costs.

[0003] The power interruption problem of existing commutation technology cannot meet the high requirements of modern power distribution systems for power supply continuity and the application needs of scenarios sensitive to power supply reliability. Therefore, there is an urgent need for a technical solution that can achieve seamless commutation with equal voltage and no instantaneous power supply interruption to break through the existing bottleneck. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a commutation control method and a commutation control device to ensure the stability and safety of the commutation process and improve the reliability and economic efficiency of power supply in low-voltage distribution areas.

[0005] In a first aspect, the present invention provides a commutation control method, the method being used to control a commutation circuit, the commutation circuit comprising three switch groups corresponding one-to-one with a three-phase line, each switch group comprising a control switch and a diode, constituting a main path and an auxiliary path between the corresponding line and the load power supply unit, the method comprising: Based on the three-phase imbalance of the low-voltage distribution area, determine whether to trigger phase switching control. If so, take the current working phase as the first phase and the target phase as the second phase. Determine whether the real-time voltage value of the first phase is greater than the real-time voltage value of the second phase. If so, control the control switches of the first phase and the second phase according to the first commutation parameter to switch the power supply path to the auxiliary path of the first phase and build the auxiliary path of the second phase. The real-time voltage values ​​of the first phase and the second phase are updated and compared. If the real-time voltage value of the first phase is less than that of the second phase, the diodes of the first phase and the second phase are controlled according to the second commutation parameters to switch the power supply path to the auxiliary path of the second phase. Based on the operating parameters and load control parameters of the second phase, the control switches and diodes of the first and second phases are controlled to switch the power supply path to the main path of the second phase.

[0006] Furthermore, the step of determining whether commutation control is triggered based on the three-phase imbalance of the low-voltage distribution area, and if so, setting the current operating phase as the first phase and the target phase as the second phase, includes: Calculate the three-phase imbalance of the low-voltage distribution area and determine whether the three-phase imbalance is less than the imbalance threshold. If not, trigger the commutation control and determine the target phase to switch. The current working phase is taken as the first phase, and the target phase to be switched is taken as the second phase.

[0007] Furthermore, before the step of determining whether the real-time voltage value of the first phase is greater than the real-time voltage value of the second phase, the method further includes: Obtain the load parameters of the low-voltage distribution area and determine whether the load parameters meet the preset load identification and protection conditions. If they do, determine whether the first phase is an energized phase based on the operating parameters of the first phase. If there is an active phase, the commutation start is triggered according to the natural commutation point, so that the low-voltage distribution area enters the commutation start state.

[0008] Furthermore, the step of acquiring the load parameters of the low-voltage distribution area and determining whether the load parameters meet the preset load identification and protection conditions includes: Obtain the load power factor, load flow direction, and current distortion rate of the low-voltage distribution area; Determine whether the load power factor is greater than or equal to a factor threshold, whether the load power flow direction is positive, and whether the current distortion rate is less than or equal to a current distortion rate threshold.

[0009] Furthermore, the step of determining whether the first phase is an energized phase based on the operating parameters of the first phase includes: The operating parameters of the first phase are collected, including the effective voltage value, power supply duration, and voltage distortion rate. Determine whether the operating parameters meet the conditions for having a power phase. The conditions for having a power phase include the effective voltage value meeting the voltage threshold range, the power supply duration being greater than the time threshold, and the voltage distortion rate being less than the voltage distortion rate threshold. If the conditions for an electrified phase are met, then the first phase is determined to be an electrified phase.

[0010] Furthermore, the step of controlling the control switches of the first phase and the second phase according to the first commutation parameters to switch the power supply path to the auxiliary path of the first phase and establish the auxiliary path of the second phase includes: Based on the first commutation parameters, a first timing switch control command is generated. The first commutation parameters include a switch action timing threshold, a safety interlock condition, and a status verification standard. According to the first timing switch control command, the control switches of the first phase and the second phase are controlled in a timing sequence so that the power supply path is switched from the main path of the first phase to the auxiliary path of the first phase, and the auxiliary path of the second phase is established.

[0011] Furthermore, the step of controlling the diodes of the first and second phases according to the second commutation parameters to switch the power supply path to the auxiliary path of the second phase includes: Based on the second commutation parameters, a second timing diode control command is generated. The second commutation parameters include a voltage trigger threshold, diode state timing, and state feedback verification standard. According to the second timing diode control command, the diodes of the first phase and the second phase are timed to switch the power supply path to the auxiliary path of the second phase and shut down the auxiliary path of the first phase.

[0012] Furthermore, the step of controlling the control switches and diodes of the first and second phases according to the operating parameters and load control parameters of the second phase to switch the power supply path to the main path of the second phase includes: Based on the operating parameters of the second phase, a third timing switch control command is generated; According to the third timing switch control command, the control switches of the first phase and the second phase are controlled in a timing sequence to turn on the main path of the second phase and turn off the auxiliary path of the first phase. Based on the load control parameters, generate the fourth-sequence switching diode control command; According to the fourth timing switch diode control command, the control switch and diode of the second phase are time-controlled so that the power supply path is switched to the main path of the second phase.

[0013] Furthermore, each switch group includes a main switch, as well as an auxiliary switch and a diode connected in parallel with the main switch; The main switch is connected between the three-phase line and the load power supply unit, forming the main path between the switch group and the corresponding line. The auxiliary switch and diode are connected in series between the three-phase line and the load power supply unit, forming an auxiliary path between the switch group and the corresponding line.

[0014] In a second aspect, the present invention provides a commutation control device for controlling a commutation circuit. The commutation circuit includes three switch groups corresponding one-to-one with a three-phase line. Each switch group includes a control switch and a diode, forming a main path and an auxiliary path between the corresponding line and the load power supply unit. The device includes: The trigger control module is used to determine whether to trigger phase switching control based on the three-phase imbalance of the low-voltage distribution area. If so, the current working phase is taken as the first phase and the target phase to be switched is taken as the second phase. The transition control module is used to determine whether the real-time voltage value of the first phase is greater than the real-time voltage value of the second phase. If so, it controls the control switches of the first phase and the second phase according to the first commutation parameters to switch the power supply path to the auxiliary path of the first phase and build the auxiliary path of the second phase. The switching control module is used to update and compare the real-time voltage values ​​of the first phase and the second phase. If the real-time voltage value of the first phase is less than the real-time voltage value of the second phase, the diodes of the first phase and the second phase are controlled according to the second commutation parameters to switch the power supply path to the auxiliary path of the second phase. The stability control module is used to control the control switches and diodes of the first and second phases according to the operating parameters and load control parameters of the second phase, so as to switch the power supply path to the main path of the second phase.

[0015] This invention provides a commutation control method and a commutation control device. This invention triggers commutation only when the imbalance exceeds the limit, which can improve the targeting of the treatment and reduce unnecessary disturbance to the power grid during commutation. Through phased timing command control, it can ensure continuous power supply to the load during the transition period, avoid inrush current and arcing, extend the life of commutation equipment, and reduce the commutation switching time. This invention can ensure the stability and safety of the commutation process and effectively improve the stability of power supply in low-voltage distribution areas and the efficiency of three-phase balance treatment. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the commutation control method in an embodiment of the present invention; Figure 2 This is a schematic diagram of the commutation circuit in an embodiment of the present invention; Figure 3 This is a schematic diagram of the commutation control device in an embodiment of the present invention; Figure label: 10. Trigger control module; 20. Transition control module; 30. Switching control module; 40. Stabilization control module. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0018] Please see Figure 1 The commutation control method proposed in the first embodiment of the present invention includes steps S10 to S40: Step S10: Based on the three-phase imbalance of the low-voltage distribution area, determine whether to trigger phase switching control. If so, take the current working phase as the first phase and the target phase as the second phase. Step S20: Determine whether the real-time voltage value of the first phase is greater than the real-time voltage value of the second phase. If so, control the control switches of the first phase and the second phase according to the first commutation parameter to switch the power supply path to the auxiliary path of the first phase and build the auxiliary path of the second phase. Step S30: Update and compare the real-time voltage values ​​of the first phase and the second phase. If the real-time voltage value of the first phase is less than the real-time voltage value of the second phase, control the diodes of the first phase and the second phase according to the second commutation parameters to switch the power supply path to the auxiliary path of the second phase. Step S40: Based on the operating parameters and load control parameters of the second phase, control the control switches and diodes of the first and second phases to switch the power supply path to the main path of the second phase.

[0019] This invention provides a commutation control method for three-phase lines in a low-voltage distribution area. By controlling the commutation circuit, seamless commutation of the three-phase lines can be achieved. Before describing the control method, the structure of the commutation circuit in this invention will be described first.

[0020] Please see Figure 2In this embodiment, the commutation circuit consists of three switch groups. Each switch group includes a control switch and a diode. Each switch group corresponds one-to-one with each phase line and is connected between each phase line and the load power supply unit to form a power supply path between the phase line and the load power supply unit. In a preferred embodiment, to achieve smooth and seamless commutation, the control switch of each switch group includes a main switch and an auxiliary switch. The auxiliary switch is connected in series with the diode and in parallel with the main switch. The main switch is connected between the phase line and the load power supply unit to form the main path, and the auxiliary switch and the diode are connected in series between the phase line and the load power supply unit to form the auxiliary path. Specifically, the switching group of the commutation circuit in this embodiment includes three groups: A-phase switch group, B-phase switch group, and C-phase switch group. The A-phase switch group is connected between the A-phase line and the load power supply unit, the B-phase switch group is connected between the B-phase line and the load power supply unit, and the C-phase switch group is connected between the C-phase line and the load power supply unit. The A-phase switch group includes the A-phase main switch Ka1, the A-phase auxiliary switch Ka2, and the A-phase diode Da. The B-phase switch group includes the B-phase main switch Kb1, the B-phase auxiliary switch Kb2, and the B-phase diode Db. The C-phase switch group includes the C-phase main switch Kc1, the C-phase auxiliary switch Kc2, and the C-phase diode Dc. The load power supply unit is also connected to the neutral line and the load, respectively.

[0021] This invention controls the commutation circuit to make the current magnitudes of phases A, B, and C as close as possible, thereby achieving intelligent commutation adjustment of single-phase loads in low-voltage distribution substations. This balances the three-phase loads in the substation, achieving energy saving and loss reduction, increasing the voltage at the end of the line, improving the efficiency and lifespan of transformers, reducing the tripping and power outage rate, and preventing overheating and aging of the neutral line. This solves the problems of time-consuming, labor-intensive, and poorly targeted phase adjustment.

[0022] Before performing commutation control on the above-mentioned commutation circuit, it is first necessary to determine whether commutation control should be triggered based on the three-phase imbalance of the low-voltage distribution area. The specific steps include: Calculate the three-phase imbalance of the low-voltage distribution area and determine whether the three-phase imbalance is less than the imbalance threshold. If not, trigger the commutation control and determine the target phase to switch. The current working phase is taken as the first phase, and the target phase to be switched is taken as the second phase.

[0023] In this embodiment, the three-phase unbalance of the low-voltage distribution area is first calculated. Unbalance is a professional indicator in power systems that measures the degree of imbalance between three-phase voltage or current. It is defined as the percentage of the root mean square value of the negative-sequence or zero-sequence fundamental component to the positive-sequence fundamental component. To simplify the calculation, this embodiment uses a simplified formula for the three-phase unbalance: Three-phase unbalance = (maximum current - minimum current) / maximum current × 100%. The control terminal of the commutation circuit uses the method provided by this invention to control the commutation circuit. The control terminal can be installed on the low-voltage outgoing side of the distribution transformer to collect the three-phase current and voltage data on the low-voltage outgoing side of the transformer in real time and control the commutation switch group. The commutation switch group is installed at each T-junction of the single-phase load on the power supply line, and the commutation action is performed through the commutation switch group.

[0024] The real-time current values ​​of phase A, phase B, phase C, and neutral wire are collected and analyzed to obtain the maximum and minimum phase current values. Then, the three-phase imbalance is calculated using the simplified formula mentioned above. Since a large circulating current will be generated in the neutral wire when the three-phase distribution area is unbalanced, the unbalanced state of the distribution area can be more accurately reflected through the two dimensions of three-phase current deviation and neutral wire current magnitude after the neutral wire current is included.

[0025] The calculated three-phase imbalance is then compared with a preset imbalance threshold. If it is less than the threshold, the current power supply phase remains unchanged; otherwise, commutation control is triggered. The imbalance threshold can be set according to the characteristics of the transformer area load, such as 10%. Subsequent actions are only triggered when the three-phase imbalance exceeds the threshold, improving the targeted nature of the management and reducing unnecessary disturbances to the power grid during commutation. When commutation control is triggered, the target phase for switching is determined. The specific determination method can refer to conventional methods, and there are no restrictions on the selection method of the target phase for switching.

[0026] In actual commutation control, there are six commutation methods: A to B, A to C, B to A, B to C, C to A, and C to B. For ease of description, the following embodiments all take phase A as the current working phase (i.e., the main switch of phase A switch group is in the open state, and the power supply path of the load is the main path of phase A line), and take phase B as the target phase for switching as an example to explain the control method. In the following description, phase A refers to the first phase, and phase B refers to the second phase. The control commands corresponding to phase A switch group and phase B switch group actually refer to the control commands of the first phase switch group and the second phase switch group.

[0027] In a preferred embodiment, to improve commutation stability, the present invention requires identifying the load status of the low-voltage distribution area before commutation to ensure that the current system power supply condition is good and to avoid commutation risks under adverse conditions. Specific steps include: Obtain the load parameters of the low-voltage distribution area and determine whether the load parameters meet the preset load identification and protection conditions. If they do, determine whether the first phase is an energized phase based on the operating parameters of the first phase. If there is an active phase, the commutation start is triggered according to the natural commutation point, so that the low-voltage distribution area enters the commutation start state.

[0028] In this embodiment, the current power supply system's operating conditions are first analyzed to determine if any adverse conditions exist, ensuring commutation safety from the source and laying a reliable foundation for subsequent precise commutation and three-phase balance management. Specifically, by analyzing the load power factor, load flow direction, and current distortion rate, adverse conditions such as voltage fluctuations caused by low load power factor, reverse flow disrupting grid balance, and high harmonics damaging components are filtered out. This embodiment presets load identification and protection conditions, confirming the current operating status by determining whether the load power factor, load flow direction, and current distortion rate meet these conditions.

[0029] Load power factor is a crucial parameter in power systems. Under ideal sinusoidal voltage conditions, it is defined as the ratio of active power to apparent power. The protection condition for load power factor is that it must be greater than or equal to a threshold value. This threshold value must meet energy efficiency requirements. If this protection condition is met, the load power status is normal. Conversely, if the load power factor is below the threshold, it indicates that the reactive power ratio is too high, which can easily cause voltage fluctuations or equipment overload during commutation. In this case, the load power status is deemed abnormal, and commutation is prohibited. Load flow direction refers to the distribution and flow of electrical load (demand) in the power system. If the load flow direction is positive, meaning electrical energy flows from the grid to the load without backfeeding from distributed sources, the load flow direction is normal. If the load flow direction is negative, meaning the load feeds back to the grid, commutation may disrupt the grid power balance or even cause malfunctions in protection devices. In this case, the status is deemed abnormal, and commutation is prohibited. Current distortion rate is an indicator of the degree of current distortion. It can be expressed as the ratio of the effective value of the distorted current to the effective value of the total current. The protection condition for current distortion rate is that the current distortion rate is less than or equal to the current distortion rate threshold. If this protection condition is met, it indicates that the load current is normal, and commutation can proceed. Conversely, if the load current is abnormal, it indicates that the load harmonic content is too high, the commutation circuit is prone to overheating and damage under high-frequency harmonics, and the commutation operation may amplify harmonic interference. In this case, the load current state is judged to be abnormal, and commutation is prohibited. Only when all the above protection conditions are met is it considered that the current operating condition is good, and subsequent commutation operations can be carried out. Otherwise, the commutation start is directly terminated to avoid the risk of commutation under adverse operating conditions from the source.

[0030] Based on the premise that the current operating conditions meet the requirements for commutation, in a preferred embodiment, the present invention performs a matching analysis on the main control timing sequence and the commutation switch timing sequence before commutation to ensure accurate execution of the commutation action. Specifically, the main control timing sequence refers to the three-phase sequence defined by the internal logic of the control terminal, such as phase A in the software corresponding to physical phase A. The commutation switch phase sequence refers to the physical phase sequence of the commutation switch hardware wiring, such as terminal 1 of the switch being connected to physical phase A. If the two phase sequences do not match, such as the main controller logic phase A corresponding to physical phase B, the commutation command will incorrectly switch the load to a non-target phase, leading to increased three-phase imbalance or even a short circuit. Phase sequence matching is the logical anchor point to ensure accurate commutation direction. Matching analysis is achieved through phase sequence encoding verification or voltage phase difference detection. In this way, the risk of misalignment between logical phase sequence and physical phase sequence can be completely avoided.

[0031] This embodiment verifies load power factor, load power flow direction, and load current distortion rate from multiple dimensions, allowing the commutation process to begin only when the load is in a normal state. This avoids risks such as voltage fluctuations caused by low power factor, grid imbalance caused by reverse power flow, and device overheating caused by high harmonics from the source, reducing the probability of equipment failure and grid disturbance. At the same time, by matching the main control phase sequence with the commutation switch phase sequence, it ensures that the logical phase sequence is consistent with the physical phase sequence, avoiding the aggravation of three-phase imbalance or short circuit caused by the commutation command being mistakenly switched to a non-target phase, and ensuring the accuracy of the commutation direction. Through multi-dimensional verification and phase sequence analysis, it not only improves the safety and success rate of commutation, but also provides a reliable foundation for three-phase balance management, while simplifying the operation and maintenance process and reducing long-term operating costs.

[0032] Furthermore, after determining whether the load parameters meet the load identification and protection conditions, the present invention also analyzes the operating status of the current working phase to determine whether the current working phase meets the commutation requirements. Specific steps include: The operating parameters of the first phase are collected, including the effective voltage value, power supply duration, and voltage distortion rate. Determine whether the operating parameters meet the conditions for having a power phase. The conditions for having a power phase include the effective voltage value meeting the voltage threshold range, the power supply duration being greater than the time threshold, and the voltage distortion rate being less than the voltage distortion rate threshold. If the conditions for an electrified phase are met, then the first phase is determined to be an electrified phase.

[0033] In this embodiment, assuming the first phase is phase A, the effective voltage value, power supply duration, and voltage distortion rate of phase A are collected. Then, it is determined whether these operating parameters meet preset conditions for a energized phase. These conditions include the effective voltage value meeting a voltage threshold range, the power supply duration exceeding a time threshold, and the voltage distortion rate being less than a voltage distortion rate threshold. Specifically, this embodiment pre-sets a threshold range for normal voltage operation, such as 198V~242V. If the effective voltage value of phase A meets this threshold range, the voltage is considered normal. The power supply duration must exceed the time threshold, such as 50ms, to eliminate the illusion of power supply caused by instantaneous power surges. The voltage distortion rate must be less than the voltage distortion rate threshold, such as 10%, to eliminate waveform abnormalities. When all the above conditions are met, the first phase is determined to be an energized phase. If the first phase is a de-energized phase (e.g., voltage < 198V, or power supply duration < 50ms) or a faulty phase (e.g., voltage distortion rate > 10%), initiating commutation would cause load power failure or equipment impact. Therefore, commutation is stopped to avoid ineffective actions and ensure commutation safety.

[0034] When the first phase is energized, the natural commutation point is determined by analyzing the instantaneous voltage values ​​of the first and second phases. In this embodiment, the commutation conditions include the first phase current not exceeding the rated value to avoid commutation under overload conditions, and the existence of a natural commutation point. The natural commutation point refers to the moment when the line voltage waveforms of the two phases crossing and their instantaneous values ​​are equal. Therefore, when the instantaneous voltages of phases A and B are equal, commutation is triggered, and the commutation start state is entered. This embodiment utilizes the characteristic of zero voltage difference to achieve shock-free commutation. The triggering principle is that in the AC sinusoidal waveform, for example, the instantaneous voltages of phases A and B will have two equal moments per cycle (20ms). When switching the power supply circuits of phases A and B, according to Ohm's law, there is no additional inrush current at the moment of commutation (inrush current peak value ≤ 1.1 times the rated current). After entering the commutation start state, subsequent actions will be triggered immediately to synchronize the commutation process with the moment of voltage equality, reducing commutation impact.

[0035] In this embodiment, by detecting the effective value of the current working phase voltage, the active phase is accurately selected, avoiding load power outages and equipment impacts caused by power failure or faulty phase switching from the source, thus ensuring safe switching. The instantaneous voltage of the three phases is collected only when there is an active phase, and combined with the switching conditions, the switching start state is ensured to be safe and necessary. The characteristic of the instantaneous equality of the voltage of two phases within the AC cycle is used to trigger switching, protecting sensitive loads and circuit devices. The switching process is synchronized with this moment, reducing action delay. At the same time, it triggers adaptation to dynamic load scenarios, ensuring power supply continuity, laying the foundation for the smooth transfer and balance management of three-phase loads, and also simplifying the system control logic and reducing timing complexity.

[0036] In the commutation start-up state, the real-time voltage values ​​of the first phase and the second phase are collected. When the real-time voltage value of the first phase is greater than that of the second phase, a corresponding control command is generated according to the preset commutation parameters to perform timing control on the control switches of the first phase and the second phase. The specific steps include: Based on the first commutation parameters, a first timing switch control command is generated. The first commutation parameters include a switch action timing threshold, a safety interlock condition, and a status verification standard. According to the first timing switch control command, the control switches of the first phase and the second phase are controlled in a timing sequence so that the power supply path is switched from the main path of the first phase to the auxiliary path of the first phase, and the auxiliary path of the second phase is established.

[0037] In this embodiment, the first commutation parameter refers to the standardized and executable digital parameter generated based on the hardware actions during the commutation start-up phase under the aforementioned three-phase imbalance management requirements (such as switching from phase A to phase B), thereby providing a rigid basis for instruction generation.

[0038] During commutation startup, the first commutation parameters are generated according to the first timing sequence only when the voltage of phase A is higher than that of phase B. This conforms to the natural flow of energy and avoids the risk of inrush current during reverse switching. The first commutation parameters include switch action timing thresholds, safety interlock conditions, and status verification standards. The switch action timing thresholds refer to the control sequence of the switches within the two-phase switch groups that need to be commutated. For example, after the auxiliary switch Ka2 of phase A is closed, the main switch Ka1 of phase A is released after a 50μs delay. This timing constraint at the initial stage of commutation can prevent power interruption caused by the main circuit breaking first and the auxiliary circuit not being connected. The safety interlock conditions refer to the limitation of the voltage difference between the two phases being commutated, such as a voltage difference of less than 5%, to ensure commutation safety. The status verification standards refer to the conditions that the system state must meet before and after the command is executed. For example, when the auxiliary switch Kb2 of phase B is closed, the voltage of phase B must be within a safe range to avoid abnormal voltage access. After the main switch Ka1 of phase A is released, its insulation resistance must be checked to be ≥10MΩ to ensure that the main circuit is completely disconnected. It should be noted that the commutation parameters, operating parameters, and load control parameters in this embodiment and subsequent embodiments can be set according to the actual situation of the low-voltage distribution area. Only preferred methods are given here, not specific limitations.

[0039] In the commutation start-up state, the power supply path of the load is switched from the main path of phase A to the auxiliary path by controlling the control switches of phase A and phase B switch groups, while simultaneously establishing the auxiliary path of phase B to achieve commutation transition. Based on this idea, the first timing switch control instructions generated according to the first commutation parameters include the Ka2 closing instruction, the Kb2 closing instruction, and the Ka1 release instruction. These instructions have a clear execution order and time interval. It can be understood that the first timing switch control instructions are actually a series of timing instructions. The essence of the first timing is to limit the action time interval for the safe switching of phase A from the normal power supply state to the commutation transition state. It should be noted that in this embodiment and subsequent embodiments, the parameters Ka1, Ka2, Kb1, Kb2, Da, and Db in the instructions do not only refer to the control switches and diodes of the phase A and phase B switch groups, but also to the control switches and diodes corresponding to the first and second phase switch groups. For example, the Ka2 closing instruction actually refers to the closing instruction of the auxiliary switch of the first phase switch group. Here, the Ka2 closing instruction is used only to clarify that when the first phase is phase A, this closing instruction controls the auxiliary switch of the phase A switch group. Further details will not be elaborated upon hereafter.

[0040] According to the Ka2 closing instruction in the first timing switch control instruction, the A-phase auxiliary switch Ka2 is controlled to close. After the A-phase auxiliary switch Ka2 is closed, it will form an auxiliary power supply path for the A-phase with the A-phase diode Da. This path is the key to maintaining the power supply of the A-phase after the A-phase main switch Ka1 is released. If the A-phase auxiliary switch Ka2 is not closed and the A-phase main switch Ka1 is released directly, the load will face a momentary power outage.

[0041] Then, according to the Kb2 closing command, the B-phase auxiliary switch Kb2 is closed. The closing of the B-phase auxiliary switch Kb2 does not immediately supply power to the B-phase switch group, but rather establishes the prototype of the B-phase auxiliary circuit in advance. Since the A-phase voltage is higher than the B-phase voltage at this time, the B-phase diode Db is in the reverse cutoff state (it will not form a B-phase power supply), but the early closing of the B-phase auxiliary switch Kb2 can avoid the time spent in circuit construction when switching to the B-phase later, and shorten the response time for subsequent phase switching.

[0042] Finally, according to the release command of Ka1, the A-phase main switch Ka1 is controlled to open. The release of the A-phase main switch Ka1 is to prepare for the subsequent disconnection from the A-phase main power supply. Although the A-phase main switch Ka1 has a low on-resistance, it needs to gradually transition to the auxiliary circuit during the commutation start-up stage. Releasing the A-phase main switch Ka1 can avoid the current shunting caused by the parallel connection of the main circuit and the auxiliary circuit, prevent the A-phase current distortion, and ensure the stable operation of the circuit.

[0043] In addition to specifying the execution order of the three instructions mentioned above, the first-sequence switch control command also specifies the time interval between instruction executions and the status inspection criteria after the corresponding instruction is completed. Only when the preset status verification criteria are met is the first-sequence switch control command considered to have been completed. At this time, phase A is in the commutation transition state, and the state of the control switch of the executed switch group can be recorded as the first-phase maintenance state information. This embodiment uses the first-sequence switch control command to ensure uninterrupted power supply during the commutation transition phase.

[0044] After the instructions for the commutation transition phase are executed, the real-time voltage values ​​of the first and second phases are monitored to find the moment when the real-time voltage value of the second phase is greater than that of the first phase. At this moment, the commutation phase begins. During the commutation phase, corresponding control instructions are generated based on the second commutation parameters to perform timing control on the diodes of the first and second phases. Specific steps include: Based on the second commutation parameters, a second timing diode control command is generated. The second commutation parameters include a voltage trigger threshold, diode state timing, and state feedback verification standard. According to the second timing diode control command, the diodes of the first phase and the second phase are timed to switch the power supply path to the auxiliary path of the second phase and shut down the auxiliary path of the first phase.

[0045] In this embodiment, the second commutation parameter refers to the digital control parameter for adapting the B-phase takeover power supply, generated based on the commutation pre-sequence state (i.e., the first phase maintenance state information), which serves as the basis for command generation.

[0046] During the commutation transition phase, the second commutation parameters are generated according to the second timing sequence only when the voltage of phase B is higher than that of phase A. The second commutation parameters include the voltage trigger threshold, diode state timing, and state feedback verification standard. The voltage trigger threshold refers to the trigger threshold for diode state switching. For example, when the real-time voltage value of phase B exceeds the real-time voltage value of phase A and the two are momentarily equal and the voltage difference is ≤0.5V, the diode state switching is triggered to avoid inrush current due to excessive voltage difference. The diode state timing refers to the order in which each diode is controlled. For example, the action interval between the cutoff of phase A diode Da and the conduction of phase B diode Db is defined as ≤10μs to prevent the power supply circuit from being briefly open. The state feedback verification standard refers to the verification indicators after diode switching, such as the reverse voltage of phase A diode Da ≥220V and the matching of the forward conduction current of phase B diode Db with the load current.

[0047] When phase A is in the commutation transition state, the power supply path of the load is switched from the auxiliary path of the first phase to the auxiliary path of the second phase by controlling the diodes in the switching groups of phases A and B, thereby realizing the transition from the commutation transition state of phase A to the commutation transition state of phase B. Based on this idea, the second-sequence diode control commands generated according to the second commutation parameters include the Da state cutoff command and the Db state turn-on command. These commands also have a clear execution order and time interval. The essence of the second timing is the action time interval for the safe switching from the phase A transition state to the phase B transition state.

[0048] In the first timing sequence, diode Da of phase A is in the conducting state, maintaining auxiliary power supply to phase A, while diode Db of phase B is in the cutoff state. To switch to phase B power supply, the states of both diodes need to be controlled in reverse via commands. Therefore, the Db state conduction command controls phase B diode Db to switch from the cutoff state to the conducting state, and the Da state cutoff command controls phase A diode Da to switch from the conducting state to the cutoff state. The execution of these two commands strictly follows the execution order and time interval requirements in the second timing diode control command. After the command execution is completed, it is necessary to verify whether the state feedback verification standard in the second timing diode control command is met. Only if the state feedback verification standard is met is the second timing diode control command considered to have been completed. At this time, phase B is in a commutation transition state, and the state of the diodes in the executed switching group can be recorded as the second phase switching state information.

[0049] The second timing diode control command in this embodiment matches the fast recovery drive characteristics of the diode, which can ensure that the diode responds instantaneously to state changes without switching lag, avoiding power supply abnormalities caused by device delays. This achieves no power supply interruption, no voltage drop or inrush current throughout the process, protecting the commutation circuit devices and ensuring stable load operation, laying a reliable foundation for three-phase load balancing.

[0050] When phase B is in the commutation transition state, the power supply path is switched from the second phase auxiliary path to the second phase main path by controlling the phase B switch group, thus achieving the final commutation purpose. The specific steps include: Based on the operating parameters of the second phase, a third timing switch control command is generated; According to the third timing switch control command, the control switches of the first phase and the second phase are controlled in a timing sequence to turn on the main path of the second phase and turn off the auxiliary path of the first phase. Based on the load control parameters, generate the fourth-sequence switching diode control command; According to the fourth timing switch diode control command, the control switch and diode of the second phase are time-controlled so that the power supply path is switched to the main path of the second phase.

[0051] In this embodiment, the operating parameters of the second phase are first generated according to the third timing sequence. The operating parameters of the second phase refer to the digital control parameters adapted to the main power supply of the B phase when the B phase is in the commutation transition state, which serve as the basis for command generation. The essence of the third timing sequence is to limit the action time interval for the safe switching of the B phase from the transition state to the initial power supply state of the main path. The operating parameters include switch action timing thresholds, safety interlock conditions, and state verification standards. It can be seen that the data contained in the operating parameters are consistent with the data types contained in the first commutation parameters, but the specific data are different at different stages. In this embodiment, the switch action timing thresholds contained in the operating parameters mainly target the timing limit between the auxiliary switch of the first phase and the main switch of the second phase, such as the time interval between the release of the A phase auxiliary switch Ka2 and the closing of the B phase main switch Kb1. The safety interlock condition is also the voltage value requirement between the first phase and the second phase, such as the voltage difference being less than 5%. The state verification standard refers to the state requirements that need to be met before and after the switch control command at this stage, such as the B phase main path current stability threshold.

[0052] The third-sequence switch control commands generated based on the operating parameters include the Ka2 release command and the Kb1 closing command. The Ka2 release command controls the A-phase auxiliary switch Ka2 to open, and the Kb1 closing command controls the B-phase main switch Kb1 to close at time intervals. Opening the A-phase auxiliary switch Ka2 disconnects the redundant circuit; closing the B-phase main switch Kb1 switches to the low-loss main circuit power supply, ensuring stable power supply and laying a reliable foundation for subsequent phase commutation.

[0053] When the system state meets the state verification criteria, after the third-sequence switch control command is executed, the load control parameters are generated according to the fourth sequence, triggered by the complete closure of the B-phase main switch Kb1. Based on these load control parameters, corresponding fourth-sequence switch diode control commands are then generated. The load control parameters refer to the state parameters of the control switches and diodes in the second-phase switch group, including the state of the B-phase diode Db and the state of the B-phase auxiliary switch Kb2. The purpose of the commutation termination stage is to convert the B-phase from the initial power supply state of the main path to a steady-state power supply state. Therefore, the fourth sequence essentially defines the safe switching time interval from the initial power supply state to the steady-state power supply state of the B-phase main path.

[0054] The fourth-sequence switch diode control commands generated based on the load control parameters include a Db state cutoff command and a Kb2 release command, and specify the execution order and time interval between the two commands. The Db state cutoff command controls the B-phase diode Db to switch from the conducting state to the cutoff state, and the Kb2 release command controls the B-phase auxiliary switch Kb2 to open. During the commutation transition phase (such as the second and third timing phases), the B-phase diode Db is used to maintain the continuity of power supply to the load. Once the B-phase main switch Kb1 is fully closed, the conduction of the B-phase diode Db is no longer necessary and it must be cut off to disconnect the auxiliary circuit. During the commutation transition phase, the B-phase auxiliary switch Kb2 is used in conjunction with the B-phase diode Db to form a temporary power supply circuit. After the B-phase main switch Kb1 stabilizes, the B-phase auxiliary switch Kb2 must be opened to avoid additional losses in the auxiliary circuit. The fourth timing switch diode control command can switch the B-phase main circuit from the initial power supply state (Kb1 closed, Kb2 closed) to the B-phase steady-state power supply state (Kb1 closed, Kb2 open, Db cut off). After the command is completed, the commutation cut-off state information is generated according to the B-phase steady-state power supply state. This information marks that the commutation action between A and B phases has officially entered steady-state operation from the transition process, providing a clear state anchor point for subsequent three-phase balance monitoring and equipment operation and maintenance.

[0055] In this embodiment, by cutting off the auxiliary path formed by the B-phase diode Db and the B-phase auxiliary switch Kb2, the current is transmitted only through the low-resistance B-phase main switch Kb1, reducing additional path losses and helping the transformer substation save energy and reduce losses. By locking the only current path, the current distribution disorder caused by the residual auxiliary path is avoided, improving power supply stability and adapting to the needs of sensitive loads. By reducing the unnecessary working time of the B-phase diode Db and the B-phase auxiliary switch Kb2 after commutation, the aging of the devices is delayed, the service life is extended, and the risk of failure is reduced. The generated commutation cutoff state information provides a clear anchor point for the commutation steady state, which facilitates subsequent three-phase balance monitoring and fault diagnosis, simplifies the operation and maintenance process, helps the three-phase current balance, improves the power supply quality of the transformer substation, and solves problems such as neutral line overheating and transformer bias.

[0056] This embodiment provides a commutation control method that analyzes the real-time three-phase current and the real-time neutral current to reflect the unbalanced state of the distribution area. Commutation is triggered only when the unbalance exceeds the limit, which improves the targeted nature of the management and reduces unnecessary disturbances to the power grid caused by commutation. Through phased timing command control, it can ensure continuous power supply to the load during the transition period, avoid inrush current and arcing, extend the life of the commutation equipment, and reduce the time spent on commutation switching. This invention effectively improves the stability of power supply in low-voltage distribution areas and the efficiency of three-phase balance management.

[0057] Please see Figure 3Based on the same inventive concept, the second embodiment of this invention proposes a commutation control device. The device is used to control a commutation circuit, which includes three switch groups corresponding one-to-one with the three-phase lines. Each switch group includes a control switch and a diode, forming a main path and an auxiliary path between the corresponding line and the load power supply unit, including: The trigger control module 10 is used to determine whether to trigger phase switching control based on the three-phase imbalance of the low-voltage distribution area. If so, the current working phase is taken as the first phase and the target phase to be switched is taken as the second phase. The transition control module 20 is used to determine whether the real-time voltage value of the first phase is greater than the real-time voltage value of the second phase. If so, it controls the control switches of the first phase and the second phase according to the first commutation parameters to switch the power supply path to the auxiliary path of the first phase and build the auxiliary path of the second phase. The switching control module 30 is used to update and compare the real-time voltage values ​​of the first phase and the second phase. If the real-time voltage value of the first phase is less than the real-time voltage value of the second phase, the diodes of the first phase and the second phase are controlled according to the second commutation parameters to switch the power supply path to the auxiliary path of the second phase. The stability control module 40 is used to control the control switches and diodes of the first and second phases according to the operating parameters and load control parameters of the second phase, so as to switch the power supply path to the main path of the second phase.

[0058] The technical features and effects of the commutation control device proposed in this embodiment are the same as those of the method proposed in this embodiment, and will not be repeated here. Each module in the above-mentioned commutation control device can be implemented entirely or partially through software, hardware, or a combination thereof. Each module can be embedded in or independent of the processor in a computer device in hardware form, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0059] In summary, the present invention provides a commutation control method and device. The method determines whether commutation control is triggered based on the three-phase imbalance of the low-voltage distribution area. If so, the current operating phase is designated as the first phase, and the target phase is designated as the second phase. It then determines whether the real-time voltage value of the first phase is greater than that of the second phase. If so, it controls the control switches of the first and second phases according to first commutation parameters to switch the power supply path to the auxiliary path of the first phase and establish an auxiliary path for the second phase. The real-time voltage values ​​of the first and second phases are updated and compared. If the real-time voltage value of the first phase is less than that of the second phase, the diodes of the first and second phases are controlled according to second commutation parameters to switch the power supply path to the auxiliary path of the second phase. Finally, the control switches and diodes of the first and second phases are controlled according to the operating parameters and load control parameters of the second phase to switch the power supply path to the main path of the second phase. This invention can achieve energy saving and loss reduction, increase the voltage at the end of the line, improve the efficiency and lifespan of various devices on the line, ensure the stability and safety of the commutation process, and effectively improve the power supply reliability and operating economy of low-voltage distribution areas.

[0060] The various embodiments in this specification are described in a progressive manner. For directly identical or similar parts of the embodiments, refer to each other. Each embodiment focuses on its differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0061] The embodiments described above are merely preferred embodiments of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various improvements and substitutions without departing from the technical principles of this invention, and these improvements and substitutions should also be considered within the scope of protection of this application. Therefore, the scope of protection of this patent application should be determined by the scope of the claims.

Claims

1. A commutation control method, characterized in that, The method is used to control a commutation circuit, which includes three switch groups corresponding one-to-one with the three-phase lines. Each switch group includes a control switch and a diode, forming a main path and an auxiliary path between the corresponding line and the load power supply unit. The method includes: Based on the three-phase imbalance of the low-voltage distribution area, determine whether to trigger phase switching control. If so, take the current working phase as the first phase and the target phase as the second phase. Determine whether the real-time voltage value of the first phase is greater than the real-time voltage value of the second phase. If so, control the control switches of the first phase and the second phase according to the first commutation parameter to switch the power supply path to the auxiliary path of the first phase and build the auxiliary path of the second phase. The real-time voltage values ​​of the first phase and the second phase are updated and compared. If the real-time voltage value of the first phase is less than that of the second phase, the diodes of the first phase and the second phase are controlled according to the second commutation parameters to switch the power supply path to the auxiliary path of the second phase. Based on the operating parameters and load control parameters of the second phase, the control switches and diodes of the first and second phases are controlled to switch the power supply path to the main path of the second phase.

2. The commutation control method according to claim 1, characterized in that, The step of determining whether to trigger commutation control based on the three-phase imbalance of the low-voltage distribution area, and if so, setting the current working phase as the first phase and the target phase as the second phase, includes: Calculate the three-phase imbalance of the low-voltage distribution area and determine whether the three-phase imbalance is less than the imbalance threshold. If not, trigger the commutation control and determine the target phase to switch. The current working phase is taken as the first phase, and the target phase to be switched is taken as the second phase.

3. The commutation control method according to claim 1, characterized in that, Before the step of determining whether the real-time voltage value of the first phase is greater than the real-time voltage value of the second phase, the method further includes: Obtain the load parameters of the low-voltage distribution area and determine whether the load parameters meet the preset load identification and protection conditions. If they do, determine whether the first phase is an energized phase based on the operating parameters of the first phase. If there is an active phase, the commutation start is triggered according to the natural commutation point, so that the low-voltage distribution area enters the commutation start state.

4. The commutation control method according to claim 3, characterized in that, The steps of acquiring the load parameters of the low-voltage distribution area and determining whether the load parameters meet the preset load identification and protection conditions include: Obtain the load power factor, load flow direction, and current distortion rate of the low-voltage distribution area; Determine whether the load power factor is greater than or equal to a factor threshold, whether the load power flow direction is positive, and whether the current distortion rate is less than or equal to a current distortion rate threshold.

5. The commutation control method according to claim 3, characterized in that, The step of determining whether the first phase is an energized phase based on the operating parameters of the first phase includes: The operating parameters of the first phase are collected, including the effective voltage value, power supply duration, and voltage distortion rate. Determine whether the operating parameters meet the conditions for having a power phase. The conditions for having a power phase include the effective voltage value meeting the voltage threshold range, the power supply duration being greater than the time threshold, and the voltage distortion rate being less than the voltage distortion rate threshold. If the conditions for an electrified phase are met, then the first phase is determined to be an electrified phase.

6. The commutation control method according to claim 1, characterized in that, The step of controlling the control switches of the first phase and the second phase according to the first commutation parameters to switch the power supply path to the auxiliary path of the first phase and establish the auxiliary path of the second phase includes: Based on the first commutation parameters, a first timing switch control command is generated. The first commutation parameters include a switch action timing threshold, a safety interlock condition, and a status verification standard. According to the first timing switch control command, the control switches of the first phase and the second phase are controlled in a timing sequence so that the power supply path is switched from the main path of the first phase to the auxiliary path of the first phase, and the auxiliary path of the second phase is established.

7. The commutation control method according to claim 1, characterized in that, The step of controlling the diodes of the first and second phases according to the second commutation parameters to switch the power supply path to the auxiliary path of the second phase includes: Based on the second commutation parameters, a second timing diode control command is generated. The second commutation parameters include a voltage trigger threshold, diode state timing, and state feedback verification standard. According to the second timing diode control command, the diodes of the first phase and the second phase are timed to switch the power supply path to the auxiliary path of the second phase and shut down the auxiliary path of the first phase.

8. The commutation control method according to claim 1, characterized in that, The step of controlling the control switches and diodes of the first and second phases according to the operating parameters and load control parameters of the second phase to switch the power supply path to the main path of the second phase includes: Based on the operating parameters of the second phase, a third timing switch control command is generated; According to the third timing switch control command, the control switches of the first phase and the second phase are controlled in a timing sequence to turn on the main path of the second phase and turn off the auxiliary path of the first phase. Based on the load control parameters, generate the fourth-sequence switching diode control command; According to the fourth timing switch diode control command, the control switch and diode of the second phase are time-controlled so that the power supply path is switched to the main path of the second phase.

9. The commutation control method according to claim 1, characterized in that, Each switch group includes a main switch, as well as an auxiliary switch and a diode connected in parallel with the main switch; The main switch is connected between the three-phase line and the load power supply unit, forming the main path between the switch group and the corresponding line. The auxiliary switch and diode are connected in series between the three-phase line and the load power supply unit, forming an auxiliary path between the switch group and the corresponding line.

10. A commutation control device, characterized in that, The device is used to control a commutation circuit, which includes three switch groups corresponding one-to-one with the three-phase lines. Each switch group includes a control switch and a diode, forming the main path and auxiliary path between the corresponding line and the load power supply unit. The device includes: The trigger control module is used to determine whether to trigger phase switching control based on the three-phase imbalance of the low-voltage distribution area. If so, the current working phase is taken as the first phase and the target phase to be switched is taken as the second phase. The transition control module is used to determine whether the real-time voltage value of the first phase is greater than the real-time voltage value of the second phase. If so, it controls the control switches of the first phase and the second phase according to the first commutation parameters to switch the power supply path to the auxiliary path of the first phase and build the auxiliary path of the second phase. The switching control module is used to update and compare the real-time voltage values ​​of the first phase and the second phase. If the real-time voltage value of the first phase is less than the real-time voltage value of the second phase, the diodes of the first phase and the second phase are controlled according to the second commutation parameters to switch the power supply path to the auxiliary path of the second phase. The stability control module is used to control the control switches and diodes of the first and second phases according to the operating parameters and load control parameters of the second phase, so as to switch the power supply path to the main path of the second phase.

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