A charging starting device and method of a static synchronous compensator

Abstract

A charging starting device and method of a static synchronous compensator belong to the technical field of static reactive power compensation, the device comprises a pre-charging module, an LLC resonant circuit, a load switching module and a main control switch module; the pre-charging module comprises an energy storage capacitor, a first switch and a buffer resistor; the LLC resonant circuit comprises a first power switch, a second power switch, an inductor, a capacitor, a transformer and a rectifier unit; the load switching module comprises a resistor, a high resistance, a low resistance, a direct connection line and a third switch; the main control switch module comprises a second switch; the pre-charging module is connected in parallel with the LLC resonant circuit, the LLC resonant circuit is connected in series with the load switching module, and the main control switch module is connected in series with the LLC resonant circuit. The application optimizes the charging structure of the static synchronous compensator, realizes a new charging mode with controllable current, reduced resistance energy consumption, and balanced charging safety and charging efficiency, and reduces the impact pressure of the static synchronous compensator on the power grid during charging.

Description

Technical Field

[0001] This application belongs to the field of static var compensation technology, specifically relating to a charging start-up device and method for a static synchronous condenser. Background Technology

[0002] With the integration of numerous new energy sources and power electronic devices into the power grid, the grid's inertia is continuously decreasing, severely testing its voltage and frequency stability. This makes the demand for large-capacity grid-connected reactive power compensation devices increasingly urgent. As a novel compensation device, the static synchronous condenser (SSC) combines synchronous condenser technology, virtual synchronous generator technology, and supercapacitor technology. Through grid-connected control strategies, it simulates the voltage source characteristics of a synchronous motor, providing dynamic reactive power support and inertia response to the power grid. The core features of the SSC are that it requires no rotating parts, possesses rapid response capabilities, and compared to traditional static var generators and static var compensators, it has positive regulation characteristics, enabling it to increase compensation power when the grid voltage decreases, actively supporting the grid voltage. It is suitable for power grid scenarios with a high proportion of new energy integration.

[0003] However, because the capacity of supercapacitors far exceeds that of traditional DC-side supporting capacitors, and their power density is also much higher than that of traditional battery packs, the charging time and charging current during the startup of static condensers increase significantly. If left uncontrolled, this charging process will place a huge burden on the power grid. Existing technologies mostly use the charging scheme of traditional static var generators, which limits the current by connecting a single fixed-value current-limiting resistor in series in the charging circuit. Once the DC-side capacitor voltage rises to a set threshold and the voltage difference across the resistor is lower than the cut-off standard, the bypass switch is closed to cut off the resistor and switch to direct charging. However, this scheme lacks adaptability: the supercapacitor capacity of static condensers is much larger than that of traditional supporting capacitors, and the power density is much higher, resulting in a significant increase in charging time. The resistor is connected in series in the circuit for a long time, which not only wastes a lot of electrical energy but also makes it difficult to meet the power tolerance and heat dissipation requirements of the resistor. Moreover, the fixed resistor cannot be dynamically adjusted, and the large voltage difference in the early stage of charging can easily burden the power grid, while the sudden drop in current in the later stage reduces the charging efficiency, making it impossible to balance safety and efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a charging start-up device and method for a static synchronous condenser to solve the problems of low charging efficiency, energy waste, and difficulty in meeting the power tolerance and heat dissipation requirements of resistors in the prior art.

[0005] In a first aspect, embodiments of this application provide a charging start-up device for a stationary synchronous adjustment camera, the device comprising: Precharge module, LLC resonant circuit, load switching module and main control switch module; The precharge module is connected in parallel with the LLC resonant circuit, the LLC resonant circuit is connected in series with the load switching module, and the main control switch module is connected in series with the LLC resonant circuit.

[0006] Furthermore, the pre-charge module includes: an energy storage capacitor C1, a first switch S1, and a buffer resistor Rh. The buffer resistor Rh is used to charge the energy storage capacitor C1 to the rated output voltage U0 of the H-bridge power unit of the stationary synchronous condenser. The pre-charge module is used to pre-charge the energy storage capacitor of the stationary synchronous condenser. The first end of the energy storage capacitor C1 is connected to the second end of the first switch S1, and the second end of the energy storage capacitor C1 is used to connect to the H-bridge power unit of the stationary synchronous condenser. The first terminal of the first switch S1 is used to connect the H-bridge power unit of the stationary synchronous condenser, and the first switch S1 is connected in parallel with the buffer resistor Rh.

[0007] Furthermore, the LLC resonant circuit includes: a first power switch Q1, a second power switch Q2, an inductor Lr, a capacitor Cr, a transformer T, and a rectifier unit. The LLC resonant circuit is used to output a stepped voltage or a dynamic voltage. The first end of the first power switch Q1 is connected to the first end of the first switch S1, and the second end is connected to the first end of the second power switch Q2. The first terminal of the second power switch Q2 is connected to the first terminal of the inductor Lr, and the second terminal is connected to the second terminal of the energy storage capacitor C1; The second terminal of the inductor Lr is connected to the first terminal of the capacitor Cr; The second terminal of the capacitor Cr is connected to the first terminal of the primary side of the transformer T; The second terminal of the primary side of the transformer T is connected to the second terminal of the power switch Q2; The transformer T is connected in parallel with the rectifier unit; The first end of the rectifier unit is connected to the first end of the resistor R0 in the main control switch module; the second end of the rectifier unit is connected to a supercapacitor module.

[0008] Furthermore, the load switching module includes: a resistor R0, a high-resistance resistor R1, a low-resistance resistor R2, a direct connection line, and a third switch S3. The third switch S3 is a single-pole three-throw switch. The load switching module is used to limit the charging current. The second end of the resistor R0 is connected to the common connection end of the third switch S3; The third switch S3 connects the first end of the high-resistance R1 or the first end of the low-resistance R2 or a direct connection line to the second end of the resistor R0. The second end of the high-resistance R1 and the second end of the low-resistance R2 are connected to a supercapacitor module.

[0009] Furthermore, the main control switch module includes a second switch S2, which is used to control the power input on / off of the LLC resonant circuit and the load switching module. The first end of the second switch S2 is connected to the first end of the power switch Q1 in the LLC resonant circuit, and the second end of the second switch S2 is connected to the first end of the rectifier unit in the LLC resonant circuit.

[0010] Secondly, embodiments of this application also provide a charging start-up method for a static synchronous adjustment camera, the method comprising the following steps: S101. Precharge the energy storage capacitor of the stationary synchronous condenser so that the voltage of the energy storage capacitor C1 reaches the rated output voltage U0 of the H-bridge power unit. S102. Start the LLC resonant converter circuit, and control its output voltage to adapt to the charging requirements of the supercapacitor in a preset manner by adjusting the operating frequency of the LLC resonant converter circuit. At the same time, the charging current is limited in conjunction with the load switching module. The preset method includes stepped voltage regulation or dynamic voltage regulation. The load switching module includes high resistance R1, low resistance R2 and direct connection line. S103. Monitor the charging current and voltage of the supercapacitor, and adjust the output voltage of the LLC resonant converter circuit or switch to the H-bridge power unit direct charging mode according to the monitoring results; S104. Stop charging when the supercapacitor voltage reaches the set value or the supercapacitor is fully charged.

[0011] Furthermore, in step S101, the specific steps for pre-charging the energy storage capacitor of the stationary synchronous condenser are as follows: Close the first switch S1 and open the second switch S2, so that the output terminal of the H-bridge power unit forms a circuit with the energy storage capacitor C1 through the buffer resistor Rh, and the energy storage capacitor C1 is charged through the buffer resistor Rh. Monitor the voltage difference across the buffer resistor Rh. When the voltage difference is less than the set value 0.1U0, close the second switch S2 and switch the H-bridge power unit to directly charge the energy storage capacitor C1. The pre-charge is completed when the voltage of the energy storage capacitor C1 reaches the rated output voltage U0 of the H-bridge power unit.

[0012] Further, in step S102, the specific steps of the stepped voltage regulation are as follows: The first power switch Q1 and the second power switch Q2 of the LLC resonant converter circuit are alternately turned on to adjust the operating frequency, so that the LLC resonant converter circuit outputs the first transmission voltage Ucs1=1 / 5U0. The third switch S3 is connected to the high-resistance R1, and the supercapacitor is charged through the high-resistance R1, limiting the supercapacitor charging current to below Ucs1 / R1. Monitor the voltage difference across the high-resistance R1. When the voltage difference is less than the set high-resistance voltage difference Ugz, control the third switch S3 to first connect the low-resistance R2 and then disconnect the high-resistance R1, so that the supercapacitor can continue to be charged through the low-resistance R2. Monitor the voltage difference across the low-resistance R2. When the voltage difference is less than the set low-resistance voltage difference Udz, control the third switch S3 to first connect to the direct connection line, then disconnect the low-resistance R2, and continue charging through the direct connection line. Repeat the above steps to adjust the output voltage of the LLC resonant converter circuit to the second transmission voltage Ucs2, the third transmission voltage Ucs3, and the fourth transmission voltage Ucs4 in sequence. Close the second switch S2, turn off the first power switch Q1 and the second power switch Q2, and the H-bridge power unit directly charges the supercapacitor through the direct connection line.

[0013] Further, in step S102, the specific steps of the dynamic voltage regulation are as follows: Control the third switch S3 to connect to the direct line, while keeping the first switch S1 closed and the second switch S2 open; The first power switch Q1 and the second power switch Q2 of the LLC resonant converter circuit are alternately turned on to adjust the operating frequency, so that the LLC resonant converter circuit outputs a dynamic voltage Uct, which satisfies the formula:

[0014] Where Iset is the set safe charging current for the supercapacitor, R0 is the overall equivalent resistance of the line, equipment and supercapacitor, and Usc is the real-time voltage of the supercapacitor. Monitor the relationship between the dynamic voltage Uct and the rated output voltage U0. When Uct > U0, close the second switch S2 and open the first power switch Q1 and the second power switch Q2, so that the supercapacitor is directly charged by the H-bridge power unit.

[0015] Furthermore, in step S103, the specific steps for monitoring the charging current and voltage of the supercapacitor are as follows: Except for the final stage of direct charging of the H-bridge power unit, if the supercapacitor charging current is detected to be less than the set minimum acceptable charging current I0, the current voltage adjustment or resistor switching step is skipped and the next stage of charging operation is directly entered. The real-time voltage Usc of the supercapacitor is continuously monitored. When Usc reaches the preset charging termination voltage or the supercapacitor is detected to be fully charged, the process proceeds to step S104.

[0016] As can be seen from the above technical solutions, the present invention has the following advantages: In the charging start-up device and method for a static synchronous condenser disclosed in this application, the high-resistance R1 initially limits the current, while the low-resistance R2 provides transitional adjustment. Combined with the LLC resonant circuit controlling the output voltage, this avoids the inrush current caused by the large voltage difference at the beginning of charging, reducing the instantaneous load impact on the power grid. It can accurately limit the charging current and alleviate the pressure on the power grid. The LLC resonant circuit adjusts the output voltage, and the resistance value can be flexibly switched through the third switch S3. The circuit voltage difference is adjusted according to the supercapacitor voltage, so that the charging current is always maintained at a safe and high level, balancing safety and charging efficiency. The stepped voltage boost combined with the switching logic of high resistance, low resistance, and direct connection reduces the fluctuations caused by sudden changes in voltage and current. At the same time, it avoids the long-term operation of the current-limiting resistor, reduces resistor energy consumption and heat dissipation pressure, avoids the risk of resistor burnout, and ensures the safety of device startup. The resistor is activated when necessary, and low-loss energy transmission is achieved through the LLC resonant circuit, reducing or even eliminating resistor energy consumption and reducing energy waste. The dynamic adjustment adapts to the supercapacitor voltage and safe current requirements, further improving charging efficiency while ensuring charging safety. The application utilizes a stepped boost control or dynamic adjustment, load switching module, and LLC resonant circuit to limit the impact of static synchronous condensers, reduce grid pressure on charging current, achieve controllable current to maintain efficient charging, reduce control fluctuations, and significantly reduce resistance energy consumption, thus balancing charging safety and charging efficiency. Attached Figure Description

[0017] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the charging start-up device for the stationary synchronous condenser of this application.

[0019] Figure 2 This is a schematic diagram of the stationary synchronous condenser in this application.

[0020] Figure 3 This is a flowchart illustrating the charging start-up method for the static synchronous condenser of this application. Detailed Implementation

[0021] Various embodiments of the invention will be described more fully in the following detailed description of the charging start-up device and method for a stationary synchronous condenser. The invention may have various embodiments, and adjustments and modifications may be made therein. However, it should be understood that there is no intention to limit the various embodiments of the invention to the specific embodiments disclosed herein, but rather the invention should be understood to cover all modifications, equivalents, and / or alternatives falling within the spirit and scope of the various embodiments of the invention.

[0022] It should be understood that, when used in this specification, the term "comprising" indicates the presence of the described feature, integral, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0023] The terms "one embodiment" or "some embodiments" used in this application mean that one or more embodiments of this application include the specific features, structures, or characteristics described in that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this application do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized.

[0024] To facilitate a clear description of the technical solutions of this application, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" do not necessarily imply that they are different.

[0025] To make the objectives, features, and advantages of this invention more apparent and understandable, specific embodiments and accompanying drawings will be used to clearly and completely describe the technical solutions protected by this invention. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0026] Please see Figure 1 The diagram shows a charging start-up device for a stationary synchronous condenser, the device comprising: Precharge module, LLC resonant circuit, load switching module and main control switch module; The precharge module is connected in parallel with the LLC resonant circuit, the LLC resonant circuit is connected in series with the load switching module, and the main control switch module is connected in series with the LLC resonant circuit.

[0027] It should be noted that the above device, through the cooperation of the load switching module and the LLC resonant circuit, limits the charging current to reduce the charging pressure on the power grid, thereby achieving controllable current and maintaining efficient charging.

[0028] Furthermore, as a refinement and extension of the specific implementation of the above embodiments, and to fully illustrate the specific implementation process in this embodiment, another charging start-up device for a stationary synchronous condenser is provided, the device comprising: Precharge module, LLC resonant circuit, load switching module and main control switch module; The precharge module is connected in parallel with the LLC resonant circuit, the LLC resonant circuit is connected in series with the load switching module, and the main control switch module is connected in series with the LLC resonant circuit.

[0029] like Figure 2 As shown, the static synchronous condenser includes a bypass switch, an H-bridge power unit, a loop switch, and a supercapacitor module. The common connection terminal of the bypass switch is connected to the input side line of the H-bridge power unit, the output side line of the H-bridge power unit is connected to the first terminal of the loop switch, the second terminal of the loop switch is connected to the first terminal of the supercapacitor module, and the second terminal of the supercapacitor module is connected to the other side line of the H-bridge power unit, forming a working circuit that can be constructed by the bypass switch, the H-bridge power unit, the loop switch, and the supercapacitor module. The bypass switch is used to bypass control the working circuit.

[0030] The pre-charge module includes: an energy storage capacitor C1, a first switch S1, and a buffer resistor Rh. The buffer resistor Rh is used to charge the energy storage capacitor C1 to the rated output voltage U0 of the H-bridge power unit of the stationary synchronous condenser. The pre-charge module is used to pre-charge the energy storage capacitor of the stationary synchronous condenser. The first end of the energy storage capacitor C1 is connected to the second end of the first switch S1, and the second end of the energy storage capacitor C1 is used to connect to the H-bridge power unit of the stationary synchronous condenser. The first terminal of the first switch S1 is used to connect the H-bridge power unit of the stationary synchronous condenser, and the first switch S1 is connected in parallel with the buffer resistor Rh.

[0031] The LLC resonant circuit includes: a first power switch Q1, a second power switch Q2, an inductor Lr, a capacitor Cr, a transformer T, and a rectifier unit. The LLC resonant circuit is used to output stepped voltage or dynamic voltage. The first end of the first power switch Q1 is connected to the first end of the first switch S1, and the second end is connected to the first end of the second power switch Q2. The first terminal of the second power switch Q2 is connected to the first terminal of the inductor Lr, and the second terminal is connected to the second terminal of the energy storage capacitor C1; The second terminal of the inductor Lr is connected to the first terminal of the capacitor Cr; The second terminal of the capacitor Cr is connected to the first terminal of the primary side of the transformer T; The second terminal of the primary side of the transformer T is connected to the second terminal of the power switch Q2; The transformer T is connected in parallel with the rectifier unit; The first end of the rectifier unit is connected to the first end of the resistor R0 in the main control switch module; the second end of the rectifier unit is connected to a supercapacitor module.

[0032] For example, the rectifier unit includes a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4; The first end of the secondary side of the transformer T is connected to the anode of the first diode D1 and the cathode of the second diode D2, and the second end of the transformer T is connected to the anode of the third diode D3 and the cathode of the fourth diode D4. The cathode of the first diode D1 is connected to the cathode of the third diode D3 and the first end of the resistor R0 in the main control switch module. The anode of the second diode D2 is connected to the anode of the fourth diode D4; the anode of the fourth diode D4 is connected to a supercapacitor module.

[0033] The load switching module includes: a resistor R0, a high-resistance resistor R1, a low-resistance resistor R2, a direct connection line, and a third switch S3. The third switch S3 is a single-pole three-throw switch. The load switching module is used to limit the charging current. The second end of the resistor R0 is connected to the common connection end of the third switch S3; The third switch S3 connects the first end of the high-resistance R1 or the first end of the low-resistance R2 or a direct connection line to the second end of the resistor R0. The second end of the high-resistance R1 and the second end of the low-resistance R2 are connected to a supercapacitor module.

[0034] The main control switch module includes a second switch S2, which is used to control the power input on / off of the LLC resonant circuit and the load switching module. The first end of the second switch S2 is connected to the first end of the power switch Q1 in the LLC resonant circuit, and the second end of the second switch S2 is connected to the first end of the rectifier unit in the LLC resonant circuit.

[0035] Please see Figure 3 The diagram shown is a schematic flowchart of the charging start-up method for the stationary synchronous condenser of this application. The method includes: S101. Precharge the energy storage capacitor of the stationary synchronous condenser so that the voltage of the energy storage capacitor C1 reaches the rated output voltage U0 of the H-bridge power unit. It should be noted that the pre-charging stage is to establish a stable initial voltage foundation for the energy storage capacitor C1. By closing the first switch S1 and opening the second switch S2, the initial charging current is limited by the buffer resistor Rh to avoid current surges when the output terminal of the H-bridge power unit is directly connected; when the voltage difference across the buffer resistor is less than 0.1U0, the system switches to direct charging of the H-bridge to quickly stabilize the voltage to U0. S102. Start the LLC resonant converter circuit, and control its output voltage to adapt to the charging requirements of the supercapacitor in a preset manner by adjusting the operating frequency of the LLC resonant converter circuit. At the same time, the charging current is limited in conjunction with the load switching module. The preset method includes stepped voltage regulation or dynamic voltage regulation. The load switching module includes high resistance R1, low resistance R2 and direct connection line. It should be noted that the frequency regulation capability of the LLC resonant circuit and the current limiting of the load switching module are suitable for the nonlinear charging characteristics of supercapacitors. Stepped regulation gradually releases charging capacity by stepping up the voltage, combined with switching between high resistance R1 (limiting large current in the initial stage), low resistance R2 (increasing charging rate in the middle stage), and direct connection line (efficient charging in the later stage); dynamic regulation controls the current by calculating the dynamic voltage Uct in real time. Both methods take into account both safety and charging efficiency.

[0036] S103. Monitor the charging current and voltage of the supercapacitor, and adjust the output voltage of the LLC resonant converter circuit or switch to the H-bridge power unit direct charging mode according to the monitoring results; It should be noted that by monitoring the current (to avoid overcurrent) and voltage (to determine the charging progress) of the supercapacitor, the charging strategy can be optimized: if the current exceeds the limit, the LLC output voltage can be reduced or a higher resistance value can be switched; if the voltage is close to the output capability of the H-bridge (Uct≥U0), then the H-bridge can be switched to direct charging to reduce intermediate losses.

[0037] S104. Stop charging when the supercapacitor voltage reaches the set value or the supercapacitor is fully charged.

[0038] It should be noted that the stop condition is set to ensure that the voltage reaches the standard or is fully charged, thus preventing the supercapacitor from overcharging and protecting the equipment.

[0039] Furthermore, as a refinement and extension of the specific implementation methods of the above embodiments, in order to fully illustrate the specific implementation process of this embodiment, another charging start method for a stationary synchronous condenser is provided, the method comprising: S101. Precharge the energy storage capacitor of the stationary synchronous condenser so that the voltage of the energy storage capacitor C1 reaches the rated output voltage U0 of the H-bridge power unit. In step S101, the specific steps for pre-charging the energy storage capacitor of the stationary synchronous condenser are as follows: Close the first switch S1 and open the second switch S2, so that the output terminal of the H-bridge power unit forms a circuit with the energy storage capacitor C1 through the buffer resistor Rh, and the energy storage capacitor C1 is charged through the buffer resistor Rh. Monitor the voltage difference across the buffer resistor Rh. When the voltage difference is less than the set value 0.1U0, close the second switch S2 and switch the H-bridge power unit to directly charge the energy storage capacitor C1. The pre-charge is completed when the voltage of the energy storage capacitor C1 reaches the rated output voltage U0 of the H-bridge power unit.

[0040] S102. Start the LLC resonant converter circuit, and control its output voltage to adapt to the charging requirements of the supercapacitor in a preset manner by adjusting the operating frequency of the LLC resonant converter circuit. At the same time, the charging current is limited in conjunction with the load switching module. The preset method includes stepped voltage regulation or dynamic voltage regulation. The load switching module includes high resistance R1, low resistance R2 and direct connection line. In step S102, the specific steps of the stepped voltage regulation are as follows: The first power switch Q1 and the second power switch Q2 of the LLC resonant converter circuit are alternately turned on to adjust the operating frequency, so that the LLC resonant converter circuit outputs the first transmission voltage Ucs1=1 / 5U0. The third switch S3 is connected to the high-resistance R1, and the supercapacitor is charged through the high-resistance R1, limiting the supercapacitor charging current to below Ucs1 / R1. Monitor the voltage difference across the high-resistance R1. When the voltage difference is less than the set high-resistance voltage difference Ugz, control the third switch S3 to first connect the low-resistance R2 and then disconnect the high-resistance R1, so that the supercapacitor can continue to be charged through the low-resistance R2. Monitor the voltage difference across the low-resistance R2. When the voltage difference is less than the set low-resistance voltage difference Udz, control the third switch S3 to first connect to the direct connection line, then disconnect the low-resistance R2, and continue charging through the direct connection line. Repeat the above steps to adjust the output voltage of the LLC resonant converter circuit to the second transmission voltage Ucs2, the third transmission voltage Ucs3, and the fourth transmission voltage Ucs4 in sequence. Close the second switch S2, turn off the first power switch Q1 and the second power switch Q2, and the H-bridge power unit directly charges the supercapacitor through the direct connection line.

[0041] In step S102, the specific steps of the dynamic voltage regulation are as follows: Control the third switch S3 to connect to the direct line, while keeping the first switch S1 closed and the second switch S2 open; The first power switch Q1 and the second power switch Q2 of the LLC resonant converter circuit are alternately turned on to adjust the operating frequency, so that the LLC resonant converter circuit outputs a dynamic voltage Uct, which satisfies the formula:

[0042] Where Iset is the set safe charging current for the supercapacitor, R0 is the overall equivalent resistance of the line, equipment and supercapacitor, and Usc is the real-time voltage of the supercapacitor. Monitor the relationship between the dynamic voltage Uct and the rated output voltage U0. When Uct > U0, close the second switch S2 and open the first power switch Q1 and the second power switch Q2, so that the supercapacitor is directly charged by the H-bridge power unit.

[0043] S103. Monitor the charging current and voltage of the supercapacitor, and adjust the output voltage of the LLC resonant converter circuit or switch to the H-bridge power unit direct charging mode according to the monitoring results; In step S103, the specific steps for monitoring the charging current and voltage of the supercapacitor are as follows: Except for the final stage of direct charging of the H-bridge power unit, if the supercapacitor charging current is detected to be less than the set minimum acceptable charging current I0, the current voltage adjustment or resistor switching step is skipped and the next stage of charging operation is directly entered. The real-time voltage Usc of the supercapacitor is continuously monitored. When Usc reaches the preset charging termination voltage or the supercapacitor is detected to be fully charged, the process proceeds to step S104.

[0044] S104. Stop charging when the supercapacitor voltage reaches the set value or the supercapacitor is fully charged.

[0045] It should be noted that the voltage setting of the supercapacitor should be based on the characteristics of the supercapacitor itself, the startup requirements of the static synchronous condenser, the capability of the preceding charging circuit, and system safety, to ensure that the energy supply for the startup of the condenser is met, while avoiding equipment damage and taking into account charging efficiency.

[0046] In addition, the LLC resonant converter circuit can be replaced with a bidirectional energy transmission CLLC resonant converter circuit, or a mirror starter with the same structure as the charging starter can be added to the discharge circuit, and the discharge current can be limited using the same current control logic as the charging process.

[0047] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0048] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A charging start-up device for a stationary synchronous camera, characterized in that, The device includes: a precharge module, an LLC resonant circuit, a load switching module, and a main control switch module; The precharge module is connected in parallel with the LLC resonant circuit, the LLC resonant circuit is connected in series with the load switching module, and the main control switch module is connected in series with the LLC resonant circuit.

2. The charging and starting device for the stationary synchronous conversion camera according to claim 1, characterized in that, The pre-charge module includes: an energy storage capacitor C1, a first switch S1, and a buffer resistor Rh. The buffer resistor Rh is used to charge the energy storage capacitor C1 to the rated output voltage U0 of the H-bridge power unit of the stationary synchronous condenser. The pre-charge module is used to pre-charge the energy storage capacitor of the stationary synchronous condenser. The first end of the energy storage capacitor C1 is connected to the second end of the first switch S1, and the second end of the energy storage capacitor C1 is used to connect to the H-bridge power unit of the stationary synchronous condenser. The first terminal of the first switch S1 is used to connect the H-bridge power unit of the stationary synchronous condenser, and the first switch S1 is connected in parallel with the buffer resistor Rh.

3. The charging start device for a stationary synchronous camera according to claim 2, characterized in that, The LLC resonant circuit includes: a first power switch Q1, a second power switch Q2, an inductor Lr, a capacitor Cr, a transformer T, and a rectifier unit. The LLC resonant circuit is used to output stepped voltage or dynamic voltage. The first end of the first power switch Q1 is connected to the first end of the first switch S1, and the second end is connected to the first end of the second power switch Q2. The first terminal of the second power switch Q2 is connected to the first terminal of the inductor Lr, and the second terminal is connected to the second terminal of the energy storage capacitor C1; The second terminal of the inductor Lr is connected to the first terminal of the capacitor Cr; The second terminal of the capacitor Cr is connected to the first terminal of the primary side of the transformer T; The second terminal of the primary side of the transformer T is connected to the second terminal of the power switch Q2; The transformer T is connected in parallel with the rectifier unit; The first end of the rectifier unit is connected to the first end of the resistor R0 in the main control switch module; the second end of the rectifier unit is connected to a supercapacitor module.

4. The charging start device for a stationary synchronous conversion camera according to claim 3, characterized in that, The load switching module includes: a resistor R0, a high-resistance resistor R1, a low-resistance resistor R2, a direct connection line, and a third switch S3. The third switch S3 is a single-pole three-throw switch. The load switching module is used to limit the charging current. The second end of the resistor R0 is connected to the common connection end of the third switch S3; The third switch S3 connects the first end of the high-resistance R1 or the first end of the low-resistance R2 or a direct connection line to the second end of the resistor R0. The second end of the high-resistance R1 and the second end of the low-resistance R2 are connected to a supercapacitor module.

5. The charging start device for a stationary synchronous camera according to claim 4, characterized in that, The main control switch module includes a second switch S2, which is used to control the power input on / off of the LLC resonant circuit and the load switching module. The first end of the second switch S2 is connected to the first end of the power switch Q1 in the LLC resonant circuit, and the second end of the second switch S2 is connected to the first end of the rectifier unit in the LLC resonant circuit.

6. A charging start-up method for a static synchronous camera, characterized in that, The method is implemented based on the charging start-up device of the static synchronous conversion camera as described in claim 5, and the method includes the following steps: S101. Precharge the energy storage capacitor of the stationary synchronous condenser so that the voltage of the energy storage capacitor C1 reaches the rated output voltage U0 of the H-bridge power unit. S102. Start the LLC resonant converter circuit, and control its output voltage to adapt to the charging requirements of the supercapacitor in a preset manner by adjusting the operating frequency of the LLC resonant converter circuit. At the same time, the charging current is limited in conjunction with the load switching module. The preset method includes stepped voltage regulation or dynamic voltage regulation. The load switching module includes high resistance R1, low resistance R2 and direct connection line. S103. Monitor the charging current and voltage of the supercapacitor, and adjust the output voltage of the LLC resonant converter circuit or switch to the H-bridge power unit direct charging mode according to the monitoring results; S104. Stop charging when the supercapacitor voltage reaches the set value or the supercapacitor is fully charged.

7. The charging start-up method for a stationary synchronous camera according to claim 6, characterized in that, In step S101, the specific steps for pre-charging the energy storage capacitor of the stationary synchronous condenser are as follows: Close the first switch S1 and open the second switch S2, so that the output terminal of the H-bridge power unit forms a circuit with the energy storage capacitor C1 through the buffer resistor Rh, and the energy storage capacitor C1 is charged through the buffer resistor Rh. Monitor the voltage difference across the buffer resistor Rh. When the voltage difference is less than the set value 0.1U0, close the second switch S2 and switch the H-bridge power unit to directly charge the energy storage capacitor C1. The pre-charge is completed when the voltage of the energy storage capacitor C1 reaches the rated output voltage U0 of the H-bridge power unit.

8. The charging start-up method for a stationary synchronous camera according to claim 6, characterized in that, In step S102, the specific steps of the stepped voltage regulation are as follows: The first power switch Q1 and the second power switch Q2 of the LLC resonant converter circuit are alternately turned on to adjust the operating frequency, so that the LLC resonant converter circuit outputs the first transmission voltage Ucs1=1 / 5U0. The third switch S3 is connected to the high-resistance R1, and the supercapacitor is charged through the high-resistance R1, limiting the supercapacitor charging current to below Ucs1 / R1. Monitor the voltage difference across the high-resistance R1. When the voltage difference is less than the set high-resistance voltage difference Ugz, control the third switch S3 to first connect the low-resistance R2 and then disconnect the high-resistance R1, so that the supercapacitor can continue to be charged through the low-resistance R2. Monitor the voltage difference across the low-resistance R2. When the voltage difference is less than the set low-resistance voltage difference Udz, control the third switch S3 to first connect to the direct connection line, then disconnect the low-resistance R2, and continue charging through the direct connection line. Repeat the above steps to adjust the output voltage of the LLC resonant converter circuit to the second transmission voltage Ucs2, the third transmission voltage Ucs3, and the fourth transmission voltage Ucs4 in sequence. Close the second switch S2, turn off the first power switch Q1 and the second power switch Q2, and the H-bridge power unit directly charges the supercapacitor through the direct connection line.

9. The charging start-up method for a stationary synchronous camera according to claim 6, characterized in that, In step S102, the specific steps of the dynamic voltage regulation are as follows: Control the third switch S3 to connect to the direct line, while keeping the first switch S1 closed and the second switch S2 open; The first power switch Q1 and the second power switch Q2 of the LLC resonant converter circuit are alternately turned on to adjust the operating frequency, so that the LLC resonant converter circuit outputs a dynamic voltage Uct, which satisfies the formula: Where Iset is the set safe charging current for the supercapacitor, R is the overall equivalent resistance of the line, equipment and supercapacitor, and Usc is the real-time voltage of the supercapacitor. Monitor the relationship between the dynamic voltage Uct and the rated output voltage U0. When Uct > U0, close the second switch S2 and open the first power switch Q1 and the second power switch Q2, so that the supercapacitor is directly charged by the H-bridge power unit.

10. The charging start-up method for a stationary synchronous camera according to claim 6, characterized in that, In step S103, the specific steps for monitoring the charging current and voltage of the supercapacitor are as follows: Except for the final stage of direct charging of the H-bridge power unit, if the supercapacitor charging current is detected to be less than the set minimum acceptable charging current I0, the current voltage adjustment or resistor switching step is skipped and the next stage of charging operation is directly entered. The real-time voltage Usc of the supercapacitor is continuously monitored. When Usc reaches the preset charging termination voltage or the supercapacitor is detected to be fully charged, the process proceeds to step S104.

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