Conversion control method and device for hybrid automatic transfer switch

Abstract

The present invention discloses a switching control method for a hybrid automatic transfer switch. The hybrid automatic transfer switch includes a main power supply branch and a short-time power supply branch; the method includes: S1, under normal circumstances, constructing a corresponding ideal sinusoidal voltage command value for each power supply; S2, at the stage when the mechanical transfer switch starts to convert and the moving and static contacts have not yet separated, the load voltage is regulated with 0.9-1.1 times the ideal sinusoidal voltage command value of the power supply to be converted as the target; S3, in the arcing stage, the load voltage is regulated with the ideal sinusoidal voltage command correction value of the power supply to be converted as the target; S4, in the last stage before the conversion is completed, the load voltage is regulated with the amplitude and frequency within the set range as the target. The present invention also discloses a switching control device for a hybrid automatic transfer switch and a hybrid automatic transfer switch. The present invention can effectively reduce the output power required by the power module in the short-time power supply branch.

Description

Technical Field

[0001] The present invention relates to an automatic transfer switch electrical appliance, in particular to a hybrid automatic transfer switch electrical appliance. Background Art

[0002] Automatic transfer switching devices (ATSEs) are primarily used in emergency power supply systems to monitor power circuits and switch one or more load circuits from one power source to another. During the switching process, an arc is generated when the mechanical contacts separate. This arc causes the circuit to remain conductive even after the mechanical contacts separate. If the arc is not extinguished promptly, it can cause a short circuit between the two power sources. To improve reliability, ATSEs must not only be designed with conventional arc extinguishers but also control the switching speed to a minimum, typically 30ms or longer. This results in a prolonged load outage during the switching process.

[0003] For equipment requiring continuous power, traditional mechanical ATSEs struggle to meet these requirements. To meet these demands, online UPSs or STSs are often used. However, these products are expensive, bulky, and require high maintenance. They also incur relatively high losses during normal operation and impose specific requirements on the load equipment.

[0004] To ensure both continuous load power supply and rapid arc extinguishing, ensuring reliability during power switching, researchers have proposed hybrid automatic transfer switches (ATSs). These combine power electronics technology with traditional mechanical ATSEs. During the ATSE power switching process, they use power electronics inverter technology to regulate the load voltage, ensuring rapid arc extinguishing while also providing short-term energy to the load, ensuring reliability and continuity of load power. For example, Chinese invention patent CN112768274B discloses a hybrid dual-power conversion system that primarily includes a main power supply S1, a backup power supply S2, a mechanical automatic transfer switch (ATS), a power electronic device, and a controller for controlling the power electronic device. The output of the power electronic device is connected to the load, forming a power supply circuit L1. The load is connected to the power supply via the ATS, forming a power supply circuit L2. The controller processes the sampled information and performs calculations using a predefined algorithm to generate a PWM signal to control the power electronic device. This effectively shortens the load power-off time during power switching and achieves rapid arc extinguishing. However, the power electronic device in this solution requires a relatively high-power power module, resulting in high system cost and large hardware volume. In addition, there is still room for further reduction in the power-off time of the load during the power conversion process. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide a conversion control method for a hybrid automatic transfer switch electrical appliance, which can further reduce the power-off time of the load during the power conversion process, effectively reduce the output power required by the power module, reduce system costs, and reduce hardware volume.

[0006] The present invention specifically adopts the following technical solutions to solve the above technical problems:

[0007] A switching control method for a hybrid automatic transfer switch electrical appliance, the hybrid automatic transfer switch electrical appliance comprising a main power supply branch consisting of at least two power sources and a mechanical transfer switch, and a short-term power supply branch for supplying power to a load during power conversion by the mechanical transfer switch; the switching control method comprising the following steps:

[0008] S1. When all power supplies are normal, construct the corresponding ideal sinusoidal voltage command value U for each power supply in real time. Siref =|U N |×cosθ i , U Siref represents the ideal sinusoidal voltage command value of the i-th power supply, |U N is the standard voltage amplitude, θ i is the positioning angle of the i-th power supply monitored in real time;

[0009] S2, when the mechanical transfer switch starts to transfer and the moving and static contacts of the mechanical transfer switch have not yet separated, the control target U is k1 times the ideal sinusoidal voltage command value of the power supply to be transferred. c_ref1 By adjusting the output of the short-time power supply branch, the load voltage U at the load power input terminal is adjusted. c For regulation, k1 is a constant between 0.9 and 1.1;

[0010] S3, after the moving and static contacts of the mechanical transfer switch are separated and the arc current I in the main power supply branch n In the stage that has not dropped to 0, U c_ref2 =U S1 +sign(I n )*Δu is the control target, and the load voltage U at the load power input terminal is adjusted by adjusting the output of the short-time power supply branch. c To regulate, U S1 is the voltage of the power supply to be converted, sign(I n ) is 1 n The sign function, when the arc current I n When the current flows from the power source to the load, the sign (I n ) takes the value of 1, otherwise it takes the value of -1; Δu is the voltage difference correction value, Δu≥0;

[0011] S4, arcing current I in the main power supply branch n From the time when the voltage drops to 0 to the time when the mechanical transfer switch is completed, the load voltage U at the load power input terminal is controlled by adjusting the output of the short-time power supply branch with the amplitude within the over-voltage and under-voltage setting points and the frequency within the over-frequency setting points. c Carry out regulation.

[0012] Preferably, the arcing current I in the main power supply branch n After it drops to 0 and the mechanical transfer switch is completed, the load voltage U is determined according to the phase difference Δθ between the power source to be converted and the target conversion power source under normal circumstances. c The control target U c_ref3 , as follows: When Δθ≤θ limit When k2 times the ideal sinusoidal voltage command value of the power supply to be converted is used as the control target U c_ref3 ; When Δθ>θ limit When k2 times the ideal sinusoidal voltage command value of the target conversion power supply is used as the control target U c_ref3 ; where k2 is a constant between 0.9 and 1.1, θ limit The preset phase difference limit is greater than or equal to 0.

[0013] More preferably, θ limit The value is 15°.

[0014] Preferably, a dual-loop control structure of voltage outer loop and current inner loop is used to adjust the output of the short-time power supply branch, and current feedforward compensation is performed based on the positive and negative sequence components of the load current fundamental of the main power supply branch, specifically as follows: according to the voltage control instruction U c_ref And the feedback load voltage U c Perform voltage loop control to obtain the output current instruction I of the short-time power supply branch c *; The fundamental positive and negative sequence components of the load current of the main power supply branch I nob to I c *Perform feedforward compensation and adjust the energy supply capacity of the short-time energy supply branch according to the energy supply capacity of the short-time energy supply branch. limit Limit the amplitude to obtain the final output current instruction I L *; then according to the current instruction I L *And the short-time power supply branch current I L The current inner loop is controlled, and then it goes through PWM modulation output and LC filtering in sequence to finally realize the load voltage U c regulation.

[0015] Further preferably, the fundamental positive and negative sequence components of the load current of the main power supply branch I nobThe observation is obtained using the following method: the sampling value of the main power supply branch current is subjected to CLARK transformation, and the current is transferred from the ABC coordinate system to the static αβ coordinate system; then, according to the positioning angle θ1 obtained by the phase lock of the power supply to be converted, the PARK transformation is performed to the dq axis positive sequence coordinate system, and the fundamental positive sequence component of the load current is obtained by instruction filtering; at the same time, -θ1 is used as the orientation angle, and the current variable in the αβ coordinate system is subjected to PARK transformation to the dq axis negative sequence coordinate system, and the fundamental negative sequence component of the load current is obtained by instruction filtering, thereby obtaining the fundamental positive and negative sequence components of the load current of the main power supply branch I nob .

[0016] Preferably, Δu is 20V.

[0017] Based on the same inventive concept, the following technical solutions can also be obtained:

[0018] A switching control device for a hybrid automatic transfer switch, comprising a main power supply branch consisting of at least two power sources and a mechanical transfer switch, and a short-term power supply branch for supplying power to a load during power conversion by the mechanical transfer switch; the switching control device comprises:

[0019] The voltage instruction construction module is used to construct the corresponding ideal sinusoidal voltage instruction value U for each power supply in real time when all power supplies are normal. Siref =|U N |×cosθ i , U Siref represents the ideal sinusoidal voltage command value of the i-th power supply, |U N | is the standard voltage amplitude, θ i is the real-time monitored positioning angle of the i-th power supply; the first control module is used to control the target U with k1 times the ideal sinusoidal voltage command value of the power supply to be converted when the mechanical conversion switch starts to convert and the moving and static contacts of the mechanical conversion switch have not yet separated. c_ref1 By adjusting the output of the short-time power supply branch, the load voltage U at the load power input terminal is adjusted. c For regulation, k1 is a constant between 0.9 and 1.1;

[0020] The second control module is used to control the arc current I in the main power supply branch after the moving and static contacts of the mechanical transfer switch are separated. n In the stage that has not dropped to 0, U c_ref2 =U S1 +sign(I n )*Δu is the control target, and the load voltage U at the load power input terminal is adjusted by adjusting the output of the short-time power supply branch. c To regulate, U S1is the voltage of the power supply to be converted, sign(I n ) is 1 n The sign function, when the arc current I n When the current flows from the power source to the load, the sign (I n ) takes the value of 1, otherwise it takes the value of -1; Δu is the voltage difference correction value, Δu≥0;

[0021] The third control module is used to control the arc current I in the main power supply branch n From the time when the voltage drops to 0 to the time when the mechanical transfer switch is completed, the load voltage U at the load power input terminal is controlled by adjusting the output of the short-time power supply branch with the amplitude within the over-voltage and under-voltage setting points and the frequency within the over-frequency setting points. c Carry out regulation.

[0022] Preferably, the third control module determines the load voltage U according to the phase difference Δθ between the power source to be converted and the target conversion power source under normal circumstances. c The control target U c_ref3 , as follows: When Δθ≤θ limit When k2 times the ideal sinusoidal voltage command value of the power supply to be converted is used as the control target U c_ref3 ; When Δθ>θ limit When k2 times the ideal sinusoidal voltage command value of the target conversion power supply is used as the control target U c_ref3 ; where k2 is a constant between 0.9 and 1.1, θ limit The preset phase difference limit is greater than or equal to 0.

[0023] More preferably, θ limit The value is 15°

[0024] Preferably, a dual-loop control structure of voltage outer loop and current inner loop is used to adjust the output of the short-time power supply branch, and current feedforward compensation is performed based on the positive and negative sequence components of the load current fundamental of the main power supply branch, specifically as follows: according to the voltage control instruction U c_ref And the feedback load voltage U c Perform voltage loop control to obtain the output current instruction I of the short-time power supply branch c *; The fundamental positive and negative sequence components of the load current of the main power supply branch I nob to I c *Perform feedforward compensation and adjust the energy supply capacity of the short-time energy supply branch according to the energy supply capacity of the short-time energy supply branch. limit Limit the amplitude to obtain the final output current instruction I L *; then according to the current instruction I L *And the short-time power supply branch current I LThe current inner loop is controlled, and then it goes through PWM modulation output and LC filtering in sequence to finally realize the load voltage U c regulation.

[0025] Further preferably, the fundamental positive and negative sequence components of the load current of the main power supply branch I nob The observation is obtained using the following method: the sampling value of the main power supply branch current is subjected to CLARK transformation, and the current is transferred from the ABC coordinate system to the static αβ coordinate system; then, according to the positioning angle θ1 obtained by the phase lock of the power supply to be converted, the PARK transformation is performed to the dq axis positive sequence coordinate system, and the fundamental positive sequence component of the load current is obtained by instruction filtering; at the same time, -θ1 is used as the orientation angle, and the current variable in the αβ coordinate system is subjected to PARK transformation to the dq axis negative sequence coordinate system, and the fundamental negative sequence component of the load current is obtained by instruction filtering, thereby obtaining the fundamental positive and negative sequence components of the load current of the main power supply branch I nob .

[0026] Preferably, Δu is 20V.

[0027] A hybrid automatic transfer switch electrical appliance comprises a main power supply branch consisting of at least two power sources and a mechanical transfer switch, and a short-time power supply branch for supplying power to a load during power conversion by the mechanical transfer switch; the hybrid automatic transfer switch electrical appliance further comprises a transfer control device as described in any of the above technical solutions.

[0028] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0029] The present invention regulates the load voltage at the load power input end in stages by adjusting the output of the short-time power supply branch, thereby realizing energy supply control during the entire conversion process of the mechanical transfer switch, shortening the undervoltage time of the load voltage during the power conversion process, and ensuring the continuity of the load operation.

[0030] The control scheme of the present invention shortens the load voltage undervoltage time as much as possible during the arcing period, and at the same time uses the power supply to be converted with arcing to supply energy to the load, effectively reducing the output pressure of the power module in the short-time power supply branch, thereby reducing hardware costs and reducing volume.

[0031] The present invention can achieve faster and more reliable arc extinguishing by regulating the expected value of the arc mouth voltage, thereby ensuring the safety and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the principle of the hybrid automatic transfer switch electrical appliance of the present invention;

[0033] Figure 2 This is a schematic diagram of the circuit structure of a specific embodiment of the hybrid automatic transfer switch electrical appliance of the present invention;

[0034] Figure 3 is a load voltage control structure diagram in a specific embodiment;

[0035] Figure 4 Schematic diagram of the principle of obtaining the positive and negative sequence components of the fundamental wave of the load current in a specific embodiment;

[0036] Figures 5 to 7 They are schematic diagrams of system states when the first to third control modules perform voltage control in specific embodiments. DETAILED DESCRIPTION

[0037] In response to the shortcomings of existing hybrid automatic transfer switching electrical appliances, the solution of the present invention is to optimize the conversion control strategy and regulate the load voltage in different ways at different stages according to the conversion law, so as to further reduce the power-off time of the load during the power conversion process while reducing the output power required by the power module, reducing system costs and reducing hardware volume.

[0038] The technical solutions proposed in the present invention are as follows:

[0039] A switching control method for a hybrid automatic transfer switch electrical appliance, the hybrid automatic transfer switch electrical appliance comprising a main power supply branch consisting of at least two power sources and a mechanical transfer switch, and a short-term power supply branch for supplying power to a load during power conversion by the mechanical transfer switch; the switching control method comprising the following steps:

[0040] S1. When all power supplies are normal, construct the corresponding ideal sinusoidal voltage command value U for each power supply in real time. Siref =|U N |×cosθ i , U Siref represents the ideal sinusoidal voltage command value of the i-th power supply, |U N | is the standard voltage amplitude, θ i is the positioning angle of the i-th power supply monitored in real time;

[0041] S2, when the mechanical transfer switch starts to transfer and the moving and static contacts of the mechanical transfer switch have not yet separated, the control target U is k1 times the ideal sinusoidal voltage command value of the power supply to be transferred. c_ref1 By adjusting the output of the short-time power supply branch, the load voltage U at the load power input terminal is adjusted. c For regulation, k1 is a constant between 0.9 and 1.1;

[0042] S3, after the moving and static contacts of the mechanical transfer switch are separated and the arc current I in the main power supply branch n In the stage that has not dropped to 0, Uc_ref2 =U S1 +sign(I n )*Δu is the control target, and the load voltage U at the load power input terminal is adjusted by adjusting the output of the short-time power supply branch. c To regulate, U S1 is the voltage of the power supply to be converted, sign(I n ) is 1 n The sign function, when the arc current I n When the current flows from the power source to the load, the sign (I n ) takes the value of 1, otherwise it takes the value of -1; Δu is the voltage difference correction value, Δu≥0;

[0043] S4, arcing current I in the main power supply branch n From the time when the voltage drops to 0 to the time when the mechanical transfer switch is completed, the load voltage U at the load power input terminal is controlled by adjusting the output of the short-time power supply branch with the amplitude within the over-voltage and under-voltage setting points and the frequency within the over-frequency setting points. c Carry out regulation.

[0044] A switching control device for a hybrid automatic transfer switch, comprising a main power supply branch consisting of at least two power sources and a mechanical transfer switch, and a short-term power supply branch for supplying power to a load during power conversion by the mechanical transfer switch; the switching control device comprises:

[0045] The voltage instruction construction module is used to construct the corresponding ideal sinusoidal voltage instruction value U for each power supply in real time when all power supplies are normal. Siref =|U N |×cosθ i , U Siref represents the ideal sinusoidal voltage command value of the i-th power supply, |U N | is the standard voltage amplitude, θ i is the real-time monitored positioning angle of the i-th power supply; the first control module is used to control the target U with k1 times the ideal sinusoidal voltage command value of the power supply to be converted when the mechanical conversion switch starts to convert and the moving and static contacts of the mechanical conversion switch have not yet separated. c_ref1 By adjusting the output of the short-time power supply branch, the load voltage U at the load power input terminal is adjusted. c For regulation, k1 is a constant between 0.9 and 1.1;

[0046] The second control module is used to control the arc current I in the main power supply branch after the moving and static contacts of the mechanical transfer switch are separated. n In the stage that has not dropped to 0, U c_ref2 =U S1+sign(I n )*Δu is the control target, and the load voltage U at the load power input terminal is adjusted by adjusting the output of the short-time power supply branch. c To regulate, U S1 is the voltage of the power supply to be converted, sign(I n ) is 1 n The sign function, when the arc current I n When the current flows from the power source to the load, the sign (I n ) takes the value of 1, otherwise it takes the value of -1; Δu is the voltage difference correction value, Δu≥0;

[0047] The third control module is used to control the arc current I in the main power supply branch n From the time when the voltage drops to 0 to the time when the mechanical transfer switch is completed, the load voltage U at the load power input terminal is controlled by adjusting the output of the short-time power supply branch with the amplitude within the over-voltage and under-voltage setting points and the frequency within the over-frequency setting points. c Carry out regulation.

[0048] Load voltage U c The specific control strategy directly determines the load voltage U c Dynamic response speed, if the existing control method is used to c Regulation, dynamic response is slow, voltage rise is slow, so the load voltage is lower than the tolerance curve specified by the standard for a long time (i.e. interruption time), resulting in load interruption and failure to meet the load power supply continuity requirements. For example, using the simplest single voltage loop to U c The response time is cycle level or above (more than 20ms); the existing voltage outer loop and current inner loop non-feedforward compensation control method is adopted, and its response time is more than 10ms; the existing voltage outer loop and current inner loop feedforward compensation control method is adopted, and the feedforward compensation is performed through the sampled feedback current, which can better meet the needs. Under non-voltage drop or voltage loss conditions, its response time can be within 3ms, but under the condition of deep voltage drop or voltage loss, the feedback current also drops due to the voltage drop, but in order to ensure reliable power supply to the load, U c The voltage needs to be raised above the undervoltage setting value. At this time, the corresponding output is large, but the feedback current value is very small, which makes it difficult to make up for the gap.

[0049] In order to solve the above problems, the present invention further proposes the following observation current feedforward compensation method to perform U c Regulation:

[0050] A dual-loop control structure with a voltage outer loop and a current inner loop is used to adjust the output of the short-time power supply branch, and current feedforward compensation is performed based on the positive and negative sequence components of the load current fundamental of the main power supply branch, as follows:

[0051] According to the voltage control instruction U in the current stage c_ref And the feedback load voltage U c Perform voltage loop control to obtain the output current instruction I of the short-time power supply branch c *; The fundamental positive and negative sequence components of the load current of the main power supply branch I nob to I c *Perform feedforward compensation and adjust the energy supply capacity of the short-time energy supply branch according to the energy supply capacity of the short-time energy supply branch. limit Limit the amplitude to obtain the final output current instruction I L *; then according to the current instruction I L *And the short-time power supply branch current I L The current inner loop is controlled, and then it goes through PWM modulation output and LC filtering in sequence to finally realize the load voltage U c regulation.

[0052] By adopting the above-mentioned observation current feedforward compensation method, a better dynamic response effect can be obtained under conditions of deep voltage drop or voltage loss. The response time can be within 3ms, and the voltage rise speed is fast, which is conducive to ensuring the reliability and continuity of load power supply.

[0053] To facilitate public understanding, the following hybrid dual power automatic transfer switch is taken as an example and the technical solution of the present invention is described in detail with reference to the accompanying drawings:

[0054] like Figure 1 As shown, the hybrid automatic transfer switch includes two power supplies S1 and S2 (output voltages are U S1 、U S2 ) and the main power supply branch L2 composed of the mechanical transfer switch, which is used for the short-time power supply branch L1 in which the power electronic device supplies power to the load during the power conversion process of the mechanical transfer switch. Both L1 and L2 pass through point P (the voltage of which is the load voltage U c ) supplies power to the load; under normal circumstances, power is supplied to the load by power supply S1 or S2, and the short-time power supply branch L1 has no output; when the power supply is switched between power supplies S1 and S2, the short-time power supply branch L1 supplies power to the load for a short time during the switching process to reduce the load power-off time.

[0055] Figure 2This is the specific circuit structure of the hybrid automatic transfer switch electrical appliance in this embodiment, which mainly includes a normal power supply (S1), a backup power supply (S2), a mechanical automatic transfer switch (ATS), a power electronic device and a controller for controlling the power electronic device. The output end of the power electronic device is connected to the load, and the load is connected to the power supply through the ATS. During normal operation, the controller is used to process the various information obtained by sampling and perform power quality detection. At this time, the power module has no output, and the load is powered by the ATS to maintain normal operation. When abnormal power quality is detected, the control is based on the processed signal and calculated through the set algorithm to finally generate a PWM signal to control the power module to output. After LC filtering, the load is short-term energy supply to maintain operation. At the same time, the controller drives the ATS to convert. When the ATS converts to the power supply on the other side, the power module stops outputting, and the load is powered by the power supply on the other side through the ATS to maintain normal operation.

[0056] The controller of this embodiment adopts a voltage outer loop and current inner loop dual loop structure to control the load voltage U c Control is performed and current feedforward compensation is performed based on the positive and negative sequence components of the load current fundamental of the main power supply branch, such as Figure 3 As shown in Figure 2, the control process is as follows:

[0057] According to the voltage control instruction U in the current stage c_ref And the feedback load voltage U c Perform voltage loop control to obtain the output current instruction I of the short-time power supply branch c *; The fundamental positive and negative sequence components of the load current of the main power supply branch I nob to I c *Perform feedforward compensation and adjust the energy supply capacity of the short-time energy supply branch according to the energy supply capacity of the short-time energy supply branch. limit Limit the amplitude to obtain the final output current instruction I L *; then according to the current instruction I L *And the short-time power supply branch current I L The current inner loop is controlled, and then it goes through PWM modulation output and LC filtering in sequence to finally realize the load voltage U c regulation.

[0058] like Figure 3 As shown, the fundamental positive and negative sequence components of the load current of the main power supply branch I nob It is obtained by observing the sampling value In of the power supply branch current, such as Figure 4As shown, the specific method is as follows: the sampling value of the main power supply branch current is subjected to CLARK transformation, and the current is transferred from the ABC coordinate system to the static αβ coordinate system; then, according to the positioning angle θ1 obtained by the phase lock of the power supply to be converted, the PARK transformation is performed to the dq axis positive sequence coordinate system, and the fundamental positive sequence component of the load current is obtained by instruction filtering; at the same time, -θ1 is used as the orientation angle, and the current variable in the αβ coordinate system is subjected to PARK transformation to the dq axis negative sequence coordinate system, and the fundamental negative sequence component of the load current is obtained by instruction filtering, thereby obtaining the fundamental positive and negative sequence components of the load current of the main power supply branch I nob .

[0059] The control method used in the power conversion process is as follows:

[0060] S1. When all power supplies are normal, construct the corresponding ideal sinusoidal voltage command value U for each power supply in real time. Siref =|U N |×cosθ i , U Siref represents the ideal sinusoidal voltage command value of the i-th power supply, |U N | is the standard voltage amplitude, θ i is the real-time monitored positioning angle of the i-th power supply:

[0061] That is, during normal operation, the positioning angles θ1 and θ2 of the power supplies S1 and S2 are obtained by phase-locking the power supplies S1 and S2, and the corresponding ideal sine wave command value U is constructed according to the two positioning angles and the standard voltage amplitude. S1ref 、U S2ref , U S1ref =|U N |*cosθ1,U S2ref =|U N |*cosθ2, where |U N | is the standard voltage amplitude.

[0062] S2, when the mechanical transfer switch starts to transfer and the moving and static contacts of the mechanical transfer switch have not yet separated, the control target U is k1 times the ideal sinusoidal voltage command value of the power supply to be transferred. c_ref1 By adjusting the output of the short-time power supply branch, the load voltage U at the load power input terminal is adjusted. c For regulation, k1 is a constant between 0.9 and 1.1:

[0063] like Figure 5As shown, when the power electronic device receives the abnormal trigger signal of the power supply S1, it automatically triggers the electromagnet drive pulse signal to drive the electromagnet, and the mechanical transfer switch starts to disconnect; after the electromagnet is driven, the movement trajectory of the moving contact of the mechanical transfer switch does not exceed the overtravel distance, the moving and static contacts of the mechanical switch are not separated, and the mechanical switch has not started arcing. At this time, the power electronic device controls the load voltage at point P according to the control instruction U c_ref1 Load voltage U at point P c The load is energized by the abnormal power supply S1 and the power electronic device. The preferred voltage outer loop instruction U c_ref =k1*U S1ref , where k1 is a constant between 0.9 and 1.1. This value range is used to ensure that the load voltage U c Not lower than the power supply undervoltage setting point and not higher than the power supply overvoltage setting point.

[0064] S3, after the moving and static contacts of the mechanical transfer switch are separated and the arc current I in the main power supply branch n In the stage that has not dropped to 0, U c_ref2 =U S1 +sign(I n )*Δu is the control target, and the load voltage U at the load power input terminal is adjusted by adjusting the output of the short-time power supply branch. c To regulate, U S1 is the voltage of the power supply to be converted, sign(I n ) is 1 n The sign function, when the arc current I n When the current flows from the power source to the load, the sign (I n ) is 1, otherwise -1; Δu is the voltage difference correction value, Δu ≥ 0:

[0065] like Figure 6 As shown, after the moving and static contacts of the mechanical transfer switch are separated, arcing begins. In the arcing mode, the power electronic device detects the arcing current In and the short-time power supply branch L1 current I L , load voltage Uc at point P, power supply S1 voltage U S1 , the voltage at point P is regulated by the short-time power supply branch L1, and the power supply S1 with arc is used to supply energy to the load; in this stage, the preferred voltage outer loop instruction, that is, the preferred value of the load voltage instruction, U c_ref =U S1 +sign(In)*Δu, where sign(In) is the sign function of In. When the current flows from the power supply S1 to the load, sign(In) takes the value of 1, otherwise it is -1; Δu is the voltage difference correction value, Δu ≥ 0, preferably 20V.

[0066] Under the control of this instruction, the expected arc voltage drop value of the arc port is Uarc_pre=U S1 -U c_ref =-sign(In)Δu, opposite to the direction of the arcing current In, the expected work done on the arc port Parc_pre=Uarc_pre*In=-sign(In)Δu*In.

[0067] It can be seen from this that the output of the short-time power supply branch L1 at this time does negative work on the arc energy at the arc port, dissipates the arc energy, and accelerates the arc extinction. Combined with the fact that the distance between the mechanical switch contacts becomes larger and larger over time, the arc gap becomes larger and larger, and the arc can be extinguished quickly. At the same time, after the arc is extinguished, the expected value of the arc port voltage can be automatically raised, which is beneficial to reducing the arc reverse recovery voltage, ensuring that the arc will not reignite after extinction, and fully ensuring the reliable extinction of the arc.

[0068] S4, arcing current I in the main power supply branch n From the time when the voltage drops to 0 to the time when the mechanical transfer switch is completed, the load voltage U at the load power input terminal is controlled by adjusting the output of the short-time power supply branch with the amplitude within the over-voltage and under-voltage setting points and the frequency within the over-frequency setting points. c To regulate:

[0069] After detecting that the arc current In drops to zero, the power supply S1 stops outputting to the load, and the load is only powered by the short-time power supply branch L1 until the mechanical transfer switch completes the conversion process; after the arc is extinguished, the load is independently powered by the short-time power supply branch. It is only necessary to ensure that the load voltage amplitude is within the over-voltage and under-voltage setting point range, and the frequency is within the over-frequency and under-frequency setting point range to ensure the normal operation of the load; considering that the mechanical transfer switch is transferring to the power supply S2, once the conversion is completed, at the moment of closing, if the controlled load voltage and U S2 There is a large voltage difference, which will form a large current impact, which may have an adverse effect on the equipment. Therefore, at this stage, the present invention further determines the optimal load voltage control instruction U according to the phase difference Δθ when the two power supplies are operating normally. c_ref :

[0070] When Δθ≤θ limit When U c_ref =k2*U S1ref ;

[0071] When Δθ>θ limit When U c_ref =k2*U S2ref ;

[0072] Among them, θ limit is the phase difference limit, θ limit≥0, preferably 15°; k2 is a constant between 0.9 and 1.1, which is not lower than the power supply undervoltage setting point and not higher than the power supply overvoltage setting point.

[0073] Of course, when Δθ>θ limit When the load is not sensitive to the large current impact at the moment of closing, it is not necessary to adopt the preferred value. c_ref =k2*U S1ref , and can also achieve the functional goal of uninterrupted load operation.

[0074] After adopting the above voltage control strategy, the energy supply control of the mechanical transfer switch is realized during the entire conversion process, the undervoltage time of the load voltage during the conversion process is shortened, and the continuity of the load operation is guaranteed; during the arcing period, while shortening the undervoltage time of the load voltage as much as possible, the power supply with arcing is used to supply energy to the load, reducing the output pressure of the power module, thereby reducing the hardware design cost and the design volume; at the same time, by regulating the expected value of the arc mouth voltage, rapid and reliable arc extinguishing is achieved, ensuring the reliability of the system.

Claims

1. A method for controlling switching of a hybrid automatic transfer switch, wherein the hybrid automatic transfer switch comprises a main power supply branch consisting of at least two power sources and a mechanical transfer switch, and a short-term power supply branch for supplying power to a load during power conversion by the mechanical transfer switch; characterized in that: The conversion control method comprises the following steps: S1. When all power supplies are normal, construct the corresponding ideal sinusoidal voltage command value U for each power supply in real time. Siref =|U N |×cosθ i , U Siref represents the ideal sinusoidal voltage command value of the i-th power supply, |U N | is the standard voltage amplitude, θ i is the positioning angle of the i-th power supply monitored in real time; S2, when the mechanical transfer switch starts to transfer and the moving and static contacts of the mechanical transfer switch have not yet separated, the control target U is k1 times the ideal sinusoidal voltage command value of the power supply to be transferred. c_ref1 By adjusting the output of the short-time power supply branch, the load voltage U at the load power input terminal is adjusted. c For regulation, k1 is a constant between 0.9 and 1.1; S3, after the moving and static contacts of the mechanical transfer switch are separated and the arc current I in the main power supply branch n In the stage that has not dropped to 0, U c_ref2 =U S1 +sign(I n )*Δu is the control target, and the load voltage U at the load power input terminal is adjusted by adjusting the output of the short-time power supply branch. c To regulate, U S1 is the voltage of the power supply to be converted, sign(I n ) is 1 n The sign function, when the arc current I n When the current flows from the power source to the load, the sign (I n ) takes the value of 1, otherwise it takes the value of -1; Δu is the voltage difference correction value, Δu≥0; S4, arcing current I in the main power supply branch n From the time when the voltage drops to 0 to the time when the mechanical transfer switch is completed, the load voltage U at the load power input terminal is controlled by adjusting the output of the short-time power supply branch with the amplitude within the over-voltage and under-voltage setting points and the frequency within the over-frequency setting points. c Carry out regulation.

2. The switching control method of the hybrid automatic transfer switch according to claim 1, characterized in that: Arcing current I in the main power supply branch n After it drops to 0 and the mechanical transfer switch is completed, the load voltage U is determined according to the phase difference Δθ between the power source to be converted and the target conversion power source under normal circumstances. c The control target U c_ref3 , as follows: When Δθ≤θ limit When k2 times the ideal sinusoidal voltage command value of the power supply to be converted is used as the control target U c_ref3 ; When Δθ>θ limit When k2 times the ideal sinusoidal voltage command value of the target conversion power supply is used as the control target U c_ref3 ; where k2 is a constant between 0.9 and 1.1, θ limit The preset phase difference limit is greater than or equal to 0.

3. The switching control method of the hybrid automatic transfer switch according to claim 2, characterized in that: θ limit The value is 15°.

4. The switching control method of the hybrid automatic transfer switch according to claim 1, wherein: A dual-loop control structure with a voltage outer loop and a current inner loop is used to adjust the output of the short-time power supply branch, and current feedforward compensation is performed based on the positive and negative sequence components of the load current fundamental of the main power supply branch, as follows: According to the voltage control instruction U in the current stage c_ref And the feedback load voltage U c Perform voltage loop control to obtain the output current instruction I of the short-time power supply branch c *; The fundamental positive and negative sequence components of the load current of the main power supply branch I nob to I c *Perform feedforward compensation and adjust the energy supply capacity of the short-time energy supply branch according to the energy supply capacity of the short-time energy supply branch. limit Limit the amplitude to obtain the final output current instruction I L *; then according to the current instruction I L *And the short-time power supply branch current I L The current inner loop is controlled, and then it goes through PWM modulation output and LC filtering in sequence to finally realize the load voltage U c regulation.

5. The switching control method of the hybrid automatic transfer switch according to claim 4, characterized in that: The fundamental positive and negative sequence components of the load current of the main power supply branch I nob The observation is obtained using the following method: the sampled value of the main power supply branch current is subjected to a CLARK transformation to convert the current from the ABC coordinate system to the static αβ coordinate system; then, based on the positioning angle θ1 obtained by phase locking the power supply to be converted, a PARK transformation is performed to convert it to the dq axis positive sequence coordinate system, and the fundamental positive sequence component of the load current is obtained through command filtering; At the same time, -θ1 is used as the orientation angle, and the current variable in the αβ coordinate system is PARK transformed to the dq axis negative sequence coordinate system. The fundamental negative sequence component of the load current is obtained by instruction filtering, and then the fundamental positive and negative sequence components of the load current of the main power supply branch are obtained. nob .

6. The switching control method of the hybrid automatic transfer switch according to claim 1, characterized in that: Δu is 20V.

7. A switching control device for a hybrid automatic transfer switch, comprising a main power supply branch consisting of at least two power sources and a mechanical transfer switch, and a short-term power supply branch for supplying power to a load during power conversion by the mechanical transfer switch; characterized in that: The conversion control device includes: a voltage instruction construction module for constructing a corresponding ideal sine wave voltage instruction value U for each power supply in real time when all power supplies are normal. Siref =|U N |×cosθ i , U Siref represents the ideal sinusoidal voltage command value of the i-th power supply, |U N | is the standard voltage amplitude, θ i is the positioning angle of the i-th power supply monitored in real time; The first control module is used to control the target voltage U with k1 times the ideal sinusoidal voltage command value of the power supply to be converted as the control target when the mechanical conversion switch starts to convert and the moving and static contacts of the mechanical conversion switch have not yet separated. c_ref1 By adjusting the output of the short-time power supply branch, the load voltage U at the load power input terminal is adjusted. c For regulation, k1 is a constant between 0.9 and 1.1; The second control module is used to control the arc current I in the main power supply branch after the moving and static contacts of the mechanical transfer switch are separated. n In the stage that has not dropped to 0, U c_ref2 =U S1 +sign(I n )*Δu is the control target, and the load voltage U at the load power input terminal is adjusted by adjusting the output of the short-time power supply branch. c To regulate, U S1 is the voltage of the power supply to be converted, sign(I n ) is 1 n The sign function, when the arc current I n When the current flows from the power source to the load, the sign (I n ) takes the value of 1, otherwise it takes the value of -1; Δu is the voltage difference correction value, Δu≥0; The third control module is used to control the arc current I in the main power supply branch n From the time when the voltage drops to 0 to the time when the mechanical transfer switch is completed, the load voltage U at the load power input terminal is controlled by adjusting the output of the short-time power supply branch with the amplitude within the over-voltage and under-voltage setting points and the frequency within the over-frequency setting points. c Carry out regulation.

8. The switching control device for a hybrid automatic transfer switch according to claim 7, characterized in that: The third control module determines the load voltage U according to the phase difference Δθ between the power source to be converted and the target conversion power source under normal conditions. c The control target U c_ref3 , as follows: When Δθ≤θ limit When k2 times the ideal sinusoidal voltage command value of the power supply to be converted is used as the control target U c_ref3 ; When Δθ>θ limit When k2 times the ideal sinusoidal voltage command value of the target conversion power supply is used as the control target U c_ref3 ; where k2 is a constant between 0.9 and 1.1, θ limit The preset phase difference limit is greater than or equal to 0.

9. The switching control device for a hybrid automatic transfer switch according to claim 8, characterized in that: θ limit The value is 15°.

10. The switching control device for a hybrid automatic transfer switch according to claim 7, characterized in that: A dual-loop control structure with a voltage outer loop and a current inner loop is used to adjust the output of the short-time power supply branch, and current feedforward compensation is performed based on the positive and negative sequence components of the load current fundamental of the main power supply branch, as follows: According to the voltage control instruction U in the current stage c_ref And the feedback load voltage U c Perform voltage loop control to obtain the output current instruction I of the short-time power supply branch c *; The fundamental positive and negative sequence components of the load current of the main power supply branch I nob to I c *Perform feedforward compensation and adjust the energy supply capacity of the short-time energy supply branch according to the energy supply capacity of the short-time energy supply branch. limit Limit the amplitude to obtain the final output current instruction I L *; then according to the current instruction I L *And the short-time power supply branch current I L The current inner loop is controlled, and then it goes through PWM modulation output and LC filtering in sequence to finally realize the load voltage U c regulation.

11. The switching control device of the hybrid automatic transfer switch according to claim 10, characterized in that: The fundamental positive and negative sequence components of the load current of the main power supply branch I nob The observation is obtained using the following method: the sampled value of the main power supply branch current is subjected to a CLARK transformation to convert the current from the ABC coordinate system to the static αβ coordinate system; then, based on the positioning angle θ1 obtained by phase locking the power supply to be converted, a PARK transformation is performed to convert it to the dq axis positive sequence coordinate system, and the fundamental positive sequence component of the load current is obtained through command filtering; At the same time, -θ1 is used as the orientation angle, and the current variable in the αβ coordinate system is PARK transformed to the dq axis negative sequence coordinate system. The fundamental negative sequence component of the load current is obtained by instruction filtering, and then the fundamental positive and negative sequence components of the load current of the main power supply branch are obtained. nob .

12. The switching control device of the hybrid automatic transfer switch according to claim 7, characterized in that: Δu is 20V.

13. A hybrid automatic transfer switch comprising a main power supply branch consisting of at least two power sources and a mechanical transfer switch, and a short-term power supply branch for supplying power to a load during power conversion by the mechanical transfer switch; characterized in that: The hybrid automatic transfer switching device further comprises a transfer control device as claimed in any one of claims 7 to 12.

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