Magnetic control fast switch and dynamic voltage restorer combined power supply switching system and method

Abstract

The invention relates to a magnetic control fast switch and dynamic voltage restorer combined power supply switching system and method. The system comprises a magnetic control switch unit, a voltage monitoring unit, a voltage compensation unit and an arc extinguishing unit. The magnetic switch unit is made of a novel magnetic control material and forms a vertical motion opening and closing mechanism through excitation and demagnetization of a built-in coil and assistance of a spring, and the vertical motion opening and closing mechanism is used for changing an internal magnetic domain and rapidly opening and closing. The voltage detection unit adopts a double-second-order generalized integral phase-locked loop voltage monitoring structure and is used for detecting instantaneous phase and frequency information of power grid voltage; the voltage compensation unit adopts a dynamic voltage restorer and is used for performing voltage compensation according to a difference value between a current power supply and an objective table power supply in a power supply switching gap so as to effectively maintain the stability of load voltage when voltage sag occurs in a power grid; and the arc extinguishing unit adopts a T-shaped double-outlet vacuum arc extinguishing chamber and is used for realizing zero arc in the whole power supply switching process. According to the invention, rapid switching of the power supply can be realized, and continuous voltage is ensured in the switching process.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetically controlled switch control, and in particular relates to a power switching system and method combining a magnetically controlled fast-cut switch with a dynamic voltage restorer. Background Art

[0002] With the continuous promotion of smart electrical equipment, daily life is increasingly dependent on the continuity of power supply, which puts higher requirements on the power supply reliability of the power sector, and magnetically controlled switches have also developed rapidly.

[0003] Currently, magnetically controlled switches include two types: ATS and STS, the former being mechanical and the latter being power electronic.

[0004] Automatic transfer switch (ATS) is a mechanical power switching device widely used in data centers, hospitals, industrial automation and other fields to ensure continuous power supply to critical loads. ATS usually consists of two or more power inputs and one output, which can automatically switch to the backup power supply when the main power fails. ATS monitors the status of the main power supply through a voltage sensor. When it detects that the main power supply is powered off or the voltage exceeds the preset range, the control system issues a switching command. After receiving the switching command, the mechanical switch operating mechanism (such as a motor-driven contactor) switches the load from the main power supply to the backup power supply. However, the mechanical moving parts are large in size and require a certain amount of time to complete the closing and opening actions, resulting in a long switching time, usually from hundreds of milliseconds to several seconds. Static transfer switch (STS) is a power switching device based on power electronics technology, which uses solid-state devices (such as thyristors, IGBTs, etc.) to achieve seamless switching between the main power supply and the backup power supply. STS can switch between power supplies in microseconds or milliseconds by controlling the conduction and shutdown of semiconductor devices. However, due to the use of complex power electronic devices, the cost is relatively high. In addition, power electronic devices may generate electromagnetic interference during the switching process, and appropriate shielding and filtering measures need to be taken. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention provides a power switching system and method combining a magnetically controlled fast-cut switch with a dynamic voltage restorer.

[0006] One of the above objects of the present invention is achieved by the following technical solution:

[0007] A power switching system combining a magnetically controlled fast-cut switch and a dynamic voltage restorer, comprising a magnetically controlled switch unit, a voltage monitoring unit, a voltage compensation unit, and an arc extinguishing unit;

[0008] The magnetic switch unit is used to control the on and off of the circuit by changing the magnetic field, changing the internal magnetic domain, and realizing fast switching; the voltage detection unit adopts a dual second-order generalized integral phase-locked loop voltage monitoring structure to detect the instantaneous phase and frequency information of the grid voltage;

[0009] The voltage compensation unit adopts a dynamic voltage restorer, which is used to perform voltage compensation according to the difference between the current power supply and the target power supply during the interval of power supply switching, so as to effectively maintain the load voltage stability when the power grid voltage drops temporarily;

[0010] The arc extinguishing unit adopts a T-shaped double-end vacuum arc extinguishing chamber, which is used to achieve zero arc in the whole process of power switching.

[0011] Furthermore, both the upper end cover and the lower end cover of the magnetic switch unit are provided with an inwardly extending boss structure.

[0012] Furthermore, a buffer spring is provided at the opening position of the magnetic switch unit to absorb and mitigate external impact or vibration force and protect the system from damage.

[0013] The second objective of the present invention is achieved through the following technical solution.

[0014] S1: pre-set the supplementary cycle of the dynamic voltage restorer, the supplementary cycle is 10ms, and its voltage is 0.4kv less than the grid voltage;

[0015] S2: Connect the main power supply and the backup power supply to the upper ports of the QF1 and QF2 molded case circuit breakers of the magnetically controlled quick-cut switch; during normal operation, the QF3 of the magnetically controlled quick-cut switch is closed, at which time the coil of QF3 is energized, the moving magnet drives the insulating rod to move toward the static contact, and the moving contact and the static contact are connected; at the same time, the QF4 of the magnetically controlled quick-cut switch is disconnected, at which time the coil of QF4 is deenergized, the moving magnet drives the insulating rod away from the static contact, the moving contact and the static contact are separated, and the main power supply supplies power to the load;

[0016] S3: Magnetic switch controller (the magnetic switch controller is responsible for controlling the opening and closing of the magnetic switch.) Real-time detection and regulation of the circuit state. When the main power fails, the magnetic switch controller detects the circuit, determines that the circuit fails, disconnects QF3, and closes QF4;

[0017] S4: During the process of disconnecting QF3 and closing QF4, there will be a gap of 10ms. During this gap, the dynamic voltage restorer starts to supplement the frequency of the 10m gap and achieve zero gap switching.

[0018] S5: When the main power supply resumes normal power supply, QF3 is closed, and the coil of QF3 is energized. The moving magnet drives the insulating rod to move toward the static contact, and the moving contact and the static contact are connected. At the same time, QF4 is disconnected, and the coil of QF4 is deenergized. The moving magnet drives the insulating rod away from the static contact, and the moving contact and the static contact are separated, and the main power supply supplies power to the load.

[0019] The advantages and positive effects of the present invention are:

[0020] 1. The power switching system and method of the present invention utilizes a dynamic voltage restorer (DVR) to provide 1-2 cycles, about 10ms, to provide voltage compensation to the load at the moment of switch switching to ensure voltage continuity.

[0021] 2. The present invention breaks through the 0.4kV dual power supply fast switching technology and realizes the 10ms switching of low-voltage dual power supplies.

[0022] 3. The present invention solves various deficiencies and contradictions of mechanical ATS and power electronic STS, and at the same time meets the advantages of fast speed, low energy consumption, small size, mechanical interlocking, impact resistance, etc., improves power supply reliability, and can achieve fast power switching through the system, avoiding malfunction of user voltage fluctuation sensitive equipment, reducing power outage time, automatic switching without human intervention, and automatically completing switching when conditions are met, avoiding the time consumed by human decision-making and manual switching in the event of power outage or failure, and realizing low-voltage load non-perceptible intelligent switching. The automatic switching time often completes the switching action within one cycle time period, and the intelligent device that directly uses the DC power supply + switching power supply completes the power switching without perception due to the effect of the switching power supply capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a cross-sectional schematic diagram of a magnetically controlled switch of the present invention;

[0024] Figure 2 It is an overall schematic diagram of the magnetically controlled switch of the present invention;

[0025] In the figure, 1. insulating connecting rod, 2. contact pressure spring, 3. opening spring, 4. static iron core, 5. excitation coil, 6. moving iron core; 7. manual opening; 8. static contact; 9. incoming line row; 10. moving contact. DETAILED DESCRIPTION

[0026] The structure of the present invention is further described below with reference to the accompanying drawings and by way of examples. It should be noted that the present examples are descriptive rather than restrictive.

[0027] A power switching system combining a magnetically controlled fast-cut switch and a dynamic voltage restorer, please see Figure 1-Figure 2The invention point is: it includes a magnetically controlled switch unit, a voltage monitoring unit, a voltage compensation unit, and an arc extinguishing unit.

[0028] The magnetic control switch unit includes a magnetic control switch and magnetic force control, including a micro switch, a manual gate rod 7, a manual opening connection piece, a limit bottom plate, a moving iron core 6, a moving contact 10, a static iron core 4, an excitation coil 5, a contact pressure spring 2, a static contact 8, an interlocking card, an opening spring 3, a static iron core bottom plate, an insulating connecting rod 1, a flexible connection, an incoming line bar 9, a locking connecting rod, etc.

[0029] By utilizing the memory characteristics of the new magnetic control material, the built-in coil is excited and demagnetized, and supplemented by a spring, a vertical motion separation and combination mechanism is formed, as shown below Figure 1 As shown: The switch with this direct-acting mechanism as the core component of the closing and opening movement is called a magnetic control switch. The magnetic control switch can show extraordinary superiority in speed, accuracy, volume, stability, and power consumption. It can be designed as a fast switch, precision control switch, ship switch, distribution network switch, and is especially suitable for primary and secondary fusion distribution network switches.

[0030] The voltage monitoring unit adopts a dual second-order generalized integrator phase-locked loop (DSOGI-PLL) voltage monitoring structure. The dual second-order generalized integrator (DSOGI) is an extended version of SOGI, which is used to extract the orthogonal components of the three-phase voltage signal. DSOGI generates the α and β components of the fundamental component on two orthogonal axes, and extracts the instantaneous phase information of the voltage signal through these orthogonal components. Differential equation of SOGI structure: The transfer function of SOGI can be expressed as:

[0031]

[0032] Where: V α (s) and V β (s) Input voltage signal V in (s); ω0 is the fundamental angular frequency of the power grid (usually ω0 = 2πf at 50Hz; k is a control parameter, usually 1 to obtain the best filtering characteristics. The task of SOGI is to extract the fundamental component of the input signal through the orthogonal component and filter out high-frequency harmonics and DC offset. For a three-phase system, the three-phase voltage u is first converted to a ,u b ,u c Convert u into α and β components, thus achieving orthogonal decomposition of the signal. α and u β Convert to the synchronously rotating coordinate system (dq coordinate system):

[0033]

[0034] After obtaining the α and β orthogonal components, the phase-locked loop (PLL) is used to extract the frequency and phase of the voltage signal. The key task of the PLL is to track the phase of the input signal so that it can be synchronized with the input signal. Through the α and β orthogonal components, the instantaneous phase θ(t) can be calculated by the inverse tangent:

[0035]

[0036] The phase error Δθ(t) of the PLL is expressed as:

[0037] Δθ(t)=θ ref (t)-θ(t)

[0038] where θ ref (t) is the reference phase.

[0039] The frequency adjustment formula of PLL is:

[0040] ω(t)=ω0+K p ·Δθ(t)+K i ∫Δθ(t)dt

[0041] Where: K p K is the proportional gain, the instantaneous response speed of the control system. i It is the integral gain that eliminates the long-term phase error. Through the phase error, the PLL can adjust the frequency and phase of the local signal to gradually synchronize it with the frequency and phase of the input signal.

[0042] By using DSOGI-PLL to detect the instantaneous phase and frequency information of the grid voltage, the system can respond quickly when the voltage drops or dual power supply switches.

[0043] The voltage compensation unit adopts a dynamic voltage restorer (DVR). The dynamic voltage restorer cooperates with the voltage detection part. The DVR is an ideal voltage compensation device for voltage sag problems. When the power grid voltage sags, it can effectively maintain the load voltage stability and reduce the harm caused by the voltage sag.

[0044] At the switching instant, calculate the difference between the current supply voltage and the target voltage:

[0045] V diff =V target -V current

[0046] Where V target is the target supply voltage, V current is the current supply voltage.

[0047] Based on the calculated voltage difference, the DVR generates a compensation voltage:

[0048] V DVR =V diff *K

[0049] Where K is the control gain, which can be adjusted according to system requirements.

[0050] Before switching, the system pre-detects the status of the current power supply and the target power supply, and confirms the switching time of the magnetic control switch (MCS). At the moment of switching, the DVR starts to provide the calculated compensation voltage to reduce the voltage drop that may occur during the switching process. The MCS quickly switches to the target power supply according to the control logic. After the switching is completed, the DVR monitors the voltage recovery and gradually reduces or turns off the compensation voltage.

[0051] The arc extinguishing unit is a fast integrated switching switch of a novel magnetic control material. The arc extinguishing unit is a T-shaped double-end vacuum arc extinguishing chamber, which is composed of moving contacts at both ends and a static contact in the middle. The two ends of the moving contact are connected by an insulating pull rod (such as Figure 2 ). The entire switching process achieves zero arc while meeting the requirements of speed and stability.

[0052] The magnetically controlled quick-cut switch of the present invention has a built-in coil excitation and demagnetization, and is supplemented by a spring to form a vertical motion separation and closing mechanism. It uses a small DVR and a magnetically controlled mechanical structure to achieve fast, accurate and stable power switching. The switching method is as follows:

[0053] S1: Pre-set the supplementary cycle of the dynamic voltage restorer (DVR), the supplementary cycle is 10ms, and its voltage is slightly smaller than the grid voltage 0.4kv;

[0054] S2: The main power supply and the backup power supply are connected to the upper ports of QF1 and QF2 molded case circuit breakers. During normal operation, QF3 of the magnetically controlled quick-cut switch is closed. At this time, the coil of QF3 is energized, and the moving magnet drives the insulating rod to move toward the static contact, and the moving contact and the static contact are connected; at the same time, QF4 of the magnetically controlled quick-cut switch is disconnected. At this time, the coil of QF4 is deenergized, and the moving magnet drives the insulating rod away from the static contact, and the moving contact and the static contact are separated, and the main power supply supplies power to the load;

[0055] S3: The controller of the magnetically controlled quick-cut switch detects and regulates the state of the circuit in real time. When the main power fails, the controller of the magnetically controlled quick-cut switch detects the circuit, determines that the circuit fails, disconnects QF3, and closes QF4;

[0056] S4: During the process of disconnecting QF3 and closing QF4, there will be a gap of 10ms. During this gap, the dynamic voltage restorer starts to supplement the frequency of the 10m gap and achieve zero gap switching.

[0057] S5: When the main power supply resumes normal power supply, QF3 is closed, and the coil of QF3 is energized. The moving magnet drives the insulating rod to move toward the static contact, and the moving contact and the static contact are connected. At the same time, QF4 is disconnected, and the coil of QF4 is deenergized. The moving magnet drives the insulating rod away from the static contact, and the moving contact and the static contact are separated, and the main power supply supplies power to the load.

[0058] The present invention compares the magnetically controlled quick-cut switch with several common operating mechanisms, including a spring operating mechanism, an eddy current repulsion mechanism, and a permanent magnet operating mechanism. The comparison results are shown in the following table:

[0059]

[0060] The present invention adopts a variety of widely used indicators for comprehensive evaluation, including the number of components, structural complexity, component reliability, manual opening and closing, precise controllability, switching speed, degree of influence by the external environment, opening and closing power, size and weight, and cost.

[0061] The above table shows that the magnetically controlled quick-cut switch has greater advantages than the spring operating mechanism, eddy current repulsion mechanism and permanent magnet operating mechanism.

[0062] In order to effectively reduce the mass of moving parts, reduce the impact and damage kinetic energy when the moving and static contacts are closed, and reduce the bounce, the upper and lower end covers are designed as boss structures, extending inward, greatly shortening the length of the moving iron core, thereby reducing the mass of the moving parts. The reduction in the mass of moving parts can effectively reduce the impact kinetic energy when the permanent magnet drive mechanism moves at high speed, prevent premature damage to the contacts, and reduce closing bounce and opening rebound. In order to reduce the rebound of the moving iron core when opening and protect the moving iron core from premature damage, a buffer spring is added to the opening position, which plays a good buffering and protective role. In addition, in the opening position, the spring has a certain amount of energy storage, so that the spring gives the moving iron core an initial acceleration when closing, greatly improving the closing speed and reducing the closing time. According to subsequent test comparisons, the time reduction is more than 25%. The opening nut installed at the lower end of the drive mechanism is the connection point for manual opening, which can be rotated up and down to adjust and reasonably arrange the position of the manual opening.

[0063] The magnetic control quick-cut switch is maintained in the closing and opening state by the strong magnetic attraction of the electromagnet. Therefore, the closing and opening action process of the magnetic drive mechanism is achieved by the electromagnetic force Fs overcoming the mechanical friction force f. The resultant force F on the moving iron core is ∑F=Fs-f. When ∑F>0, the moving iron core starts to move. When the switch is in the closing position, the moving iron core is at the bottom. The gap between the moving iron core and the bottom is very small, and the corresponding magnetic resistance is also very small, which generates a large downward attraction, tightly adsorbing the moving iron core below, forming a closing holding force. However, since the transmission shaft is made of stainless steel and does not conduct magnetism, the magnetic circuit cannot be transmitted to the lower end. When the switch needs to be opened, there is no current in the coil, and the induced magnetic field cannot be generated, and the switch completes the opening action.

[0064] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A power switching system combining a magnetically controlled fast-cut switch and a dynamic voltage restorer, characterized in that: It includes a magnetically controlled switch unit, a voltage monitoring unit, a voltage compensation unit, and an arc extinguishing unit; The magnetic switch unit is used to control the on and off of the circuit by changing the magnetic field, changing the internal magnetic domain, and realizing fast switching; the voltage detection unit adopts a dual second-order generalized integral phase-locked loop voltage monitoring structure to detect the instantaneous phase and frequency information of the grid voltage; The voltage compensation unit adopts a dynamic voltage restorer, which is used to perform voltage compensation according to the difference between the current power supply and the target power supply during the interval of power supply switching, so as to effectively maintain the load voltage stability when the power grid voltage drops temporarily; The arc extinguishing unit adopts a T-shaped double-end vacuum arc extinguishing chamber, which is used to achieve zero arc in the whole process of power switching.

2. The power switching system combining a magnetically controlled fast-cut switch and a dynamic voltage restorer according to claim 1 is characterized in that: The upper end cover and the lower end cover of the magnetic switch unit are both provided with an inwardly extending boss structure.

3. The power switching system combining a magnetically controlled fast-cut switch and a dynamic voltage restorer according to claim 1 is characterized in that: A buffer spring is provided at the opening position of the magnetic switch unit to absorb and mitigate external impact or vibration force and protect the system from damage.

4. A switching method for a power switching system using a combination of a magnetically controlled fast-cut switch and a dynamic voltage restorer as described in any one of claims 1 to 3, characterized in that: The steps include: S1: pre-set the supplementary cycle of the dynamic voltage restorer, the supplementary cycle is 10ms, and its voltage is 0.4kv less than the grid voltage; S2: Connect the main power supply and the backup power supply to the upper ports of the QF1 and QF2 molded case circuit breakers of the magnetically controlled quick-cut switch; during normal operation, the QF3 of the magnetically controlled quick-cut switch is closed, at which time the coil of QF3 is energized, the moving magnet drives the insulating rod to move toward the static contact, and the moving contact and the static contact are connected; at the same time, the QF4 of the magnetically controlled quick-cut switch is disconnected, at which time the coil of QF4 is deenergized, the moving magnet drives the insulating rod away from the static contact, the moving contact and the static contact are separated, and the main power supply supplies power to the load; S3: The magnetic switch controller detects and regulates the state of the circuit in real time. When the main power fails, the magnetic switch controller detects the circuit, determines that the circuit fails, disconnects QF3, and closes QF4; S4: During the process of disconnecting QF3 and closing QF4, there will be a gap of 10ms. During this gap, the dynamic voltage restorer starts to supplement the frequency of the 10m gap and achieve zero gap switching. S5: When the main power supply resumes normal power supply, QF3 is closed, and the coil of QF3 is energized. The moving magnet drives the insulating rod to move toward the static contact, and the moving contact and the static contact are connected. At the same time, QF4 is disconnected, and the coil of QF4 is deenergized. The moving magnet drives the insulating rod away from the static contact, and the moving contact and the static contact are separated, and the main power supply supplies power to the load.

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