Digital rectifier cabinet and control method

Abstract

The application discloses a kind of digital rectifier cabinet and control method, it is related to electric power equipment field, comprising: at least two rectifier units, each rectifier unit is connected with each other by first parallel component parallelly, for converting three-phase alternating current into direct current and outputting to direct current bus.The at least two chopping units, each chopping unit is connected with each other by second parallel component parallelly, the input end of chopping unit is connected direct current bus, for chopping conversion to direct current to output controllable direct current.Control unit is used to each rectifier unit, each chopping unit is balanced and is distributed, and when detecting fault, corresponding fault unit is controlled offline, keep remaining unit normal operation.Rectifier unit and chopping unit are completely separated and independently set, control logic decoupling, regulation precision is high, dynamic response speed is fast, can perfectly adapt to plasma load fluctuation characteristics, guarantee plasma arc stable and not extinguish, to improve the reliability and stability of power supply.

Description

Technical Field

[0001] This application relates to the field of power equipment technology, and in particular to a digital rectifier cabinet and control method. Background Technology

[0002] Plasma ignition technology is a core technology for the start-up ignition and low-load stable combustion of pulverized coal boilers in modern thermal power plants. Relying on a high-temperature, high-energy, and highly reactive plasma arc to directly ignite pulverized coal, it can significantly reduce fuel consumption during boiler start-up and improve combustion stability under low-load operation. It is a key technology for energy conservation and emission reduction in the thermal power industry. As a core actuator, the plasma generator must be provided with a continuous and stable high-power DC power supply from a dedicated DC power source. The quality of this power supply directly determines the stability of the plasma arc, the success rate of pulverized coal ignition, and the overall operational safety of the boiler. Therefore, providing a more stable and reliable power supply for plasma ignition equipment has become an urgent problem to be solved. Summary of the Invention

[0003] In view of the above problems, this application provides a digital rectifier cabinet and control method to improve power supply stability and reliability. The specific solution is as follows:

[0004] The first aspect of this application provides a digital rectifier cabinet, characterized in that it includes: a rectifier unit, a chopper unit, and a control unit;

[0005] The rectifier unit comprises at least two units, and each rectifier unit is connected in parallel with each other through a first parallel component, for converting three-phase AC power into DC power and outputting it to the DC bus.

[0006] The chopper unit comprises at least two units, and each chopper unit is connected in parallel to the others through a second parallel component. The input terminal of the chopper unit is connected to the DC bus and is used to chop and transform the DC power to output controllable DC power.

[0007] The control unit is electrically connected to each of the rectifier units and each of the chopper units. The control unit is used to perform load balancing distribution on each of the rectifier units and each of the chopper units, and to control the corresponding faulty unit to go offline when a fault is detected, so as to keep the remaining units running normally.

[0008] In one possible implementation, the rectifier unit includes: a three-phase rectifier circuit, a PFC module, a full-bridge LLC resonant converter module, and an input filter capacitor;

[0009] The three-phase rectifier circuit is connected to the three-phase AC power supply, and the input filter capacitor is connected to the three-phase rectifier circuit to filter out input voltage ripple.

[0010] The PFC module is connected to the output terminal of the three-phase rectifier circuit, and the full-bridge LLC resonant converter module is connected to the output terminal of the PFC module and outputs DC power to the DC bus.

[0011] In one possible implementation, the three-phase rectifier circuit includes: an L1 rectifier bridge and an L2 rectifier bridge; the PFC module includes a PFC switch and a freewheeling diode; and the full-bridge LLC resonant converter module includes a full-bridge switch, an LLC resonant network, and a high-frequency transformer.

[0012] In one possible implementation, the rectifier unit is configured to output in constant voltage mode to provide a stable DC bus voltage to the chopper unit.

[0013] In one possible implementation, the chopper unit includes: a bridge arm module composed of multiple sets of switching devices and an output filtering module;

[0014] The bridge arm module is connected to the DC bus, and the output filter module is connected to the output terminal of the bridge arm module to smooth the output voltage.

[0015] In one possible implementation, the bridge arm module includes: two sets of four-bridge arm structures, each set of bridge arms containing three series-connected switching devices, the switching devices being MOSFETs or IGBTs;

[0016] The output filtering module includes an inductor, an electrolytic capacitor, and a bleeder resistor, forming an LC low-pass filter circuit.

[0017] In one possible implementation, the chopper unit is controlled by a digital high-frequency switch and is configured to output controllable DC power in constant current or constant power mode.

[0018] In one possible implementation, both the first parallel component and the second parallel component are redundant parallel structures, so that if a single rectifier unit or chopper unit fails and goes offline, the remaining units can be used to re-share current and operate at reduced capacity.

[0019] In one possible implementation, the rectifier unit further includes an output-side filter capacitor connected to the output of the full-bridge LLC resonant converter module, used to filter out DC bus voltage ripple.

[0020] A second aspect of this application provides a digital rectifier cabinet control method, applied to a digital rectifier cabinet according to the first aspect or any implementation thereof, the method comprising:

[0021] The control unit collects the operating status of each rectifier unit and each chopper unit and performs load balancing power distribution.

[0022] When the control unit detects a rectifier unit failure, it controls the failed rectifier unit to go offline and redistributes the load of the remaining rectifier units.

[0023] When the control unit detects a chopper unit failure, it takes the failed chopper unit offline and redistributes the load of the remaining chopper units.

[0024] The digital rectifier cabinet and control method provided in this application, based on the above technical solution, include: at least two rectifier units, each connected in parallel via a first parallel component, for converting three-phase AC power into DC power and outputting it to the DC bus; at least two chopper units, each connected in parallel via a second parallel component, with the input of each chopper unit connected to the DC bus, for chopping and converting the DC power to output controllable DC power; and a control unit for load balancing of the rectifier and chopper units, and for controlling the corresponding faulty unit to go offline when a fault is detected, while maintaining the normal operation of the remaining units. The rectifier and chopper units are completely separated and independently configured. The rectifier units focus on AC / DC conversion, power factor correction, and bus voltage regulation, while the chopper units focus on precise output adjustment. The control logic is decoupled, resulting in high adjustment accuracy and fast dynamic response, perfectly adapting to the drastic fluctuations of plasma loads, ensuring the stable and unextinguished plasma arc, thereby improving the reliability and stability of the power supply. Attached Figure Description

[0025] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0026] Figure 1 A circuit schematic diagram of a digital rectifier cabinet provided in this application;

[0027] Figure 2 Another circuit schematic diagram of a digital rectifier cabinet provided in this application;

[0028] Figure 3 The circuit schematic of the rectifier unit provided in this application;

[0029] Figure 4 The circuit schematic of the chopper unit provided in this application;

[0030] Figure 5 A structural diagram of a digital rectifier cabinet provided in this application;

[0031] Figure 6 A structural diagram of another digital rectifier cabinet provided in this application;

[0032] Figure 7 is a flowchart of a digital rectifier cabinet control method provided by the present application. Detailed Description of the Embodiments

[0033] The embodiments of the present application are described below with reference to the accompanying drawings in the embodiments of the present application. The terms used in the embodiments section of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application.

[0034] The embodiments of the present application are described below with reference to the accompanying drawings. Those of ordinary skill in the art will appreciate that with the development of technology and the emergence of new scenarios, the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems.

[0035] The terms "first", "second" and the like in the specification and claims of the present application and the accompanying drawings are used to distinguish similar objects, and are not necessarily used to describe a specific sequence or order. It should be understood that the terms so used may be interchanged under appropriate circumstances, and this is only a distinction manner adopted when describing objects with the same attributes in the embodiments of the present application. In addition, the terms "comprising", "having" and any variations thereof are intended to cover non-exclusive inclusion, so that a process, method, system, product or device comprising a series of units is not necessarily limited to those units, but may include other units that are not clearly listed or inherent to such process, method, product or device.

[0036] At present, the rectifier cabinets supporting plasma ignition equipment are mainly divided into two technical routes, namely thyristor phase-controlled rectifier power supplies and integrated switching-mode rectifier power supplies. Both technologies have insurmountable technical defects in the actual application process, and cannot fully meet the high performance, high reliability, green and energy-saving requirements of modern plasma ignition systems for DC power supplies.

[0037] The first type of existing technology is the traditional thyristor phase-controlled rectifier power supply. This type of power supply adopts a three-phase fully controlled thyristor rectifier bridge structure, and the DC output voltage is regulated by adjusting the thyristor conduction angle. It belongs to low-frequency high-power rectification technology. The main drawbacks of this technology are as follows: First, the thyristor switching frequency is low, usually 50Hz, resulting in extremely low power density, large device size, and the need for large-capacity isolation transformers or multi-pulse rectifier transformers, which increases the footprint and installation and transportation costs. Second, the phase-controlled rectification method leads to severe distortion of the input current waveform, high harmonic content, and low power factor, usually not exceeding 0.8, causing serious harmonic pollution to the power grid and interfering with the normal operation of electrical measuring equipment in the boiler PC section. It requires additional large-capacity passive filter devices, further increasing the system size and cost. Third, the conduction angle adjustment method has high losses and serious heat generation, requiring forced air cooling or water cooling systems, resulting in high energy consumption and high operating noise. Fourth, the output ripple is large and the dynamic response speed is slow, making it unable to adapt to the characteristics of drastic fluctuations in plasma load. This can easily lead to the extinction of the plasma arc, affecting the ignition success rate. Fifth, the device lacks a modular redundancy design. A single component failure can cause the entire unit to shut down, making it impossible to achieve reduced-capacity operation and seriously threatening the safety of boiler operation.

[0038] The second type of existing technology is the integrated switching rectifier power supply. This type of power supply uses high-frequency switching conversion technology, integrating rectification, inversion, and rectification filtering functions into a single power module, belonging to the integrated switching power supply technology route. While this technology has certain advantages over phase-controlled rectification, it still has significant drawbacks in plasma ignition applications: First, the highly integrated power conversion stage means that rectification and chopping functions cannot be independently controlled, resulting in complex control logic, insufficient dynamic adjustment accuracy, and difficulty in simultaneously meeting the requirements of stable bus voltage and precise DC output control. Second, the multi-module parallel connection method only achieves simple power distribution without an intelligent collaborative control mechanism, leading to poor load distribution uniformity and a tendency for individual modules to overload and fail. Third, the switching losses during power conversion are high, and the high-frequency operation causes severe heat generation, placing extremely high demands on heat dissipation structures and installation space, and reducing long-term operational reliability. Fourth, it lacks true redundant parallel connection and automatic fault-free operation. When a single power module fails, the system cannot automatically isolate the faulty module, typically triggering a system-wide protection shutdown, making it impossible to achieve derating operation under fault conditions and failing to meet the uninterrupted power supply requirements of plasma ignition systems. Fifth, the integrated structure makes module repair and replacement difficult, fault location time long, maintenance costs high, and affects the normal production rhythm of power plants.

[0039] The third type of existing technology is conventional modular DC power supplies. These power supplies employ a multi-module parallel structure, but do not utilize a two-stage independent architecture for the rectifier and chopper units. They only achieve single-stage power conversion and parallel current sharing. Their drawbacks include: the inability to achieve independent control and redundancy between the rectifier and chopper sides, resulting in limited fault tolerance; the lack of a dedicated intelligent control unit for balanced load distribution and automatic offline handling of faulty units; the absence of active power factor correction and resonant soft-switching technology, leading to limited improvement in power factor and conversion efficiency, and insufficient harmonic suppression; and the lack of optimized design for plasma load characteristics, resulting in output stability and dynamic response speed that cannot meet stringent operating conditions.

[0040] In summary, existing rectifier cabinets for plasma ignition equipment generally suffer from technical problems such as low efficiency, low power factor, high harmonic pollution, low power density, large size, severe heat generation, lack of redundancy and fault tolerance, easy downtime due to failure, and difficult maintenance. They cannot simultaneously meet the requirements for high efficiency, energy saving, green operation, intelligence, and high reliability.

[0041] To address the aforementioned problems, this application provides a digital rectifier cabinet and its control method. The digital rectifier cabinet and control method of this application will be described in detail below with reference to the accompanying drawings.

[0042] Reference Figure 1 , Figure 1 A schematic diagram of a digital rectifier cabinet circuit is provided for an embodiment of this application, such as... Figure 1 As shown, the digital rectifier cabinet provided in this application embodiment includes: a rectifier unit 3, a chopper unit 5, and a control unit 7;

[0043] There are at least two rectifier units 3, and each rectifier unit 3 is connected in parallel with each other through a first parallel component, which is used to convert three-phase AC power into DC power and output it to the DC bus.

[0044] There are at least two chopper units 5, and each chopper unit 5 is connected in parallel with each other through a second parallel component. The input terminal of the chopper unit 5 is connected to the DC bus and is used to chop and transform DC power to output controllable DC power.

[0045] The control unit 7 is electrically connected to each rectifier unit 3 and each chopper unit 5. The control unit 7 is used to perform load balancing distribution on each rectifier unit 3 and each chopper unit 5, and to control the corresponding faulty unit to go offline when a fault is detected, so as to keep the remaining units running normally.

[0046] Specifically, the number of rectifier units 3 is set to two or more; for example, two:

[0047] Two rectifier units 3 are connected in parallel to each other through a dedicated first parallel component. The input terminals of the two rectifier units 3 are connected to the external three-phase AC power, and the output terminals are connected to the DC bus 4. The two rectifier units 3 are identical, with the same power rating and electrical characteristics. Their core function is to convert the three-phase AC power input from the AC bus 2 into stable DC power and output the DC power stably to the DC bus 4, providing the power supply basis for the subsequent chopper unit 5.

[0048] The number of chopper units 5 is also set to two. The two chopper units 5 are connected in parallel to each other through the second parallel component. The input terminals of the two chopper units 5 are connected to the DC bus 4 to receive DC power from the rectifier unit 3. The output terminals are connected to the load terminal through the output bus 6 to provide controllable DC power to the plasma generator. The two chopper units are completely identical and have consistent output characteristics and control accuracy.

[0049] The control unit 7 uses an industrial-grade digital control chip and establishes electrical connections and signal interactions with the two rectifier units 3 and the two chopper units 5 respectively. As the control core of the entire system, the control unit has two functions: First, it collects the operating parameters of the two rectifier units and the two chopper units in real time, including input voltage, output voltage, output current, and operating temperature. According to the preset control algorithm, it performs load balancing on the two rectifier units to make the output power of the two rectifier units basically the same. At the same time, it performs load balancing on the two chopper units to make the output power of the two chopper units basically the same, avoiding overload operation of a single unit and improving the stability of system operation.

[0050] Second, the system continuously monitors the fault status of the two rectifier units and two chopper units, including overvoltage faults, overcurrent faults, overtemperature faults, and short-circuit faults. Once a fault is detected in any of the rectifier units, the control unit immediately issues a control command to automatically disconnect the faulty rectifier unit, stopping its power conversion and power output. At the same time, it keeps the other normal rectifier unit running and readjusts the load distribution strategy so that the normal rectifier unit bears the full load, ensuring the stability of the DC bus voltage. Similarly, once a fault is detected in any of the chopper units, the control unit immediately disconnects the faulty chopper unit automatically, keeps the other normal chopper unit running, and redistributes the output load to ensure that the system outputs controllable DC power without interruption, achieving de-capacitance operation under fault conditions.

[0051] In this embodiment, both the first and second parallel components can adopt a combination structure of standard copper busbars and current-sharing reactors to achieve electrical connection and current sharing between the two rectifier units and between the two chopper units. This results in a simple structure, high reliability, and low cost. The rectifier units use a conventional high-frequency switching rectifier topology to convert three-phase AC to DC; the chopper units use a conventional DC / DC chopper topology to achieve precise regulation of DC voltage and current. The control unit uses digital control, combining hardware circuitry and software algorithms to achieve load balancing and fault offline functions, operating automatically without manual intervention.

[0052] The specific working process may include: three-phase AC power input to two parallel rectifier units, which convert the AC power into DC power and transmit it to the DC bus.

[0053] Two parallel chopper units draw power from the DC bus and output controllable DC power to the plasma generator through chopper conversion. The control unit monitors the operating status of all units in real time and distributes the load evenly. When a unit fails, the control unit quickly identifies and disconnects it from the system, and the remaining units automatically take over the entire load, ensuring continuous and stable operation of the system and uninterrupted operation of the plasma generator.

[0054] As can be seen from the above, the digital rectifier cabinet has a completely separate and independent rectifier unit and chopper unit. The rectifier unit focuses on AC-DC conversion, power factor correction and bus voltage regulation, while the chopper unit focuses on precise output adjustment. The control logic is decoupled, the adjustment accuracy is high, and the dynamic response speed is fast. It can perfectly adapt to the violent fluctuation characteristics of plasma load and ensure that the plasma arc is stable and does not go out.

[0055] It boasts outstanding dual redundancy and fault tolerance capabilities: multiple redundant parallel units on both the rectifier and chopper sides, coupled with intelligent control from the control unit, enable automatic offline operation in case of a single unit failure, automatic current sharing among remaining units, and uninterrupted derating operation of the system. This completely resolves the technical shortcomings of traditional power supplies, where a single point of failure results in system shutdown, significantly improving the reliability and safety of the plasma ignition system. It effectively addresses the core deficiencies of traditional power supplies, such as lack of redundancy, fault-free offline operation, and intelligent current sharing. It offers advantages such as simple structure, high reliability, stable operation, and convenient maintenance, meeting the power supply requirements of plasma ignition equipment.

[0056] In some embodiments, refer to Figure 2 As shown, the digital rectifier cabinet includes four rectifier units, four chopper units, a control unit, parallel components, a pre-processing unit 1, and a post-processing unit 8.

[0057] Among them, reference Figure 3 As shown, the rectifier unit includes:

[0058] Each rectifier unit includes a three-phase rectifier circuit, a PFC module, a full-bridge LLC resonant converter module, and an input filter capacitor.

[0059] The three-phase rectifier circuit specifically adopts an L1 and L2 rectifier bridge structure, with three-phase AC power connected to the input terminal to achieve the initial conversion of three-phase AC power to pulsating DC power.

[0060] The input filter capacitor is a large-capacity electrolytic capacitor, which is connected to the input terminal of the three-phase rectifier circuit to effectively filter out high-frequency ripple and grid interference on the input side and ensure stable input power.

[0061] The PFC module is an active power factor correction module, which specifically includes a PFC switch, a freewheeling diode, and a boost inductor. The PFC switch uses a MOSFET, and the freewheeling diode uses a fast recovery diode. It corrects the input current waveform in real time, so that the power factor reaches above 0.99 and the input harmonic content is below 5%, meeting the requirements of green operation of the power grid.

[0062] The full-bridge LLC resonant converter module specifically includes four full-bridge switches, an LLC resonant network, and a high-frequency transformer. The full-bridge switches use IGBT devices, and the LLC resonant network is composed of a resonant inductor, a resonant capacitor, and a high-frequency transformer magnetizing inductor. It operates in a resonant state, achieving zero-voltage turn-on and zero-current turn-off of the full-bridge switches, resulting in extremely low switching losses and a conversion efficiency of over 96%.

[0063] A high-frequency transformer provides electrical isolation between the input and output, enhancing the device's safety performance. The output of the full-bridge LLC resonant converter module is connected to an output-side filter capacitor, which is a high-frequency, low-impedance electrolytic capacitor to further filter out bus voltage ripple and ensure a smooth and stable DC bus voltage. The rectifier unit operates in constant voltage output mode, maintaining a constant DC bus voltage through internal closed-loop control, providing a highly stable power supply to the chopper unit.

[0064] Reference Figure 4 As shown, the chopper unit section includes a bridge arm module and an output filter module for each chopper unit.

[0065] The bridge arm module adopts a two-group four-bridge-arm structure, with three switching devices connected in series in each group of bridge arms. The switching devices are IGBT devices, which have a high overall withstand voltage rating and high output power, and can meet the high power supply requirements of plasma.

[0066] The bridge arm module achieves high-frequency chopping conversion under the control of the PWM drive signal of the control unit, adjusting the output voltage and current. The output filter module consists of an LC low-pass filter circuit composed of an inductor, an electrolytic capacitor, and a bleeder resistor. The inductor is a high-frequency iron powder core inductor, the electrolytic capacitor is a low-ripple, large-capacity capacitor, and the bleeder resistor is a high-power cement resistor, which can effectively filter out the high-frequency harmonics generated by chopping. The output ripple voltage is less than 1% of the output voltage, providing clean DC power to the plasma generator. The chopping unit adopts digital high-frequency switching control technology, and the output mode is set by the control unit. It can flexibly switch between constant current mode and constant power mode to adapt to the working requirements of the plasma generator under different operating conditions.

[0067] The two parallel components can adopt a redundant parallel structure, which consists of a dedicated parallel copper busbar, current sharing module, fast fuse, and hot-swappable interface. The four rectifier units and the four chopper units are fully redundantly connected in parallel. When a single unit fails, the fast fuse will automatically trip and the hot-swappable interface will automatically cut off the electrical connection. With the help of the control unit command, arc-free offline operation is achieved without affecting the normal operation of other units. The remaining units will automatically re-share the current, and the system will operate uninterruptedly with reduced capacity.

[0068] The control unit can use a digital control chip to perform high-speed, high-capacity data interaction with four rectifier units and four chopper units through a communication bus (such as a CAN bus). It can collect signals such as voltage, current, temperature, and fault status of each unit in real time, with a sampling frequency of not less than 10kHz, high control accuracy, and fast response speed. The control unit outputs a high-precision PWM drive signal based on the collected signals to control the switching devices inside the rectifier and chopper units to achieve all functions such as power conversion, output regulation, load balancing, and fault protection.

[0069] The pre-processing unit 1 includes a passive filter circuit and an AC contactor. The passive filter circuit filters out low-frequency harmonics from the power grid, and the AC contactor enables rapid switching control of the three-phase power supply.

[0070] The post-processing unit 8 includes a smoothing reactor to further smooth the output DC waveform and improve power supply quality. The heat dissipation unit employs an intelligent air-cooling system, where the cooling fan speed automatically matches the output power of the rectifier and chopper units. The higher the output power, the higher the fan speed, resulting in stronger heat dissipation and reduced energy consumption and operating noise. The DC busbars are arranged vertically at the rear of the cabinet and at a 90-degree angle front to back, ensuring unobstructed heat dissipation channels and improving heat dissipation efficiency.

[0071] Based on the above embodiments, the working process of this digital rectifier cabinet is as follows:

[0072] The three-phase AC power is filtered by the pre-processing unit 1 and controlled by the contactor before being input to four parallel rectifier units 3.

[0073] Each rectifier unit 3 sequentially passes through input filtering, three-phase rectification, active PFC, full-bridge LLC resonant soft-switching conversion, and output filtering to convert AC power into stable high-voltage DC power, which is then delivered to the DC bus.

[0074] Four parallel chopper units 5 obtain electrical energy from the DC bus 4, and after multi-bridge arm high-frequency chopper conversion and LC filtering, output controllable DC power, which is then processed by the subsequent smoothing reactor and supplied to the plasma generator.

[0075] Control unit 7 collects real-time operating data from all units, evenly distributes the load, and monitors fault status. When a unit fails, the control unit quickly identifies the faulty unit, automatically disconnects it, and re-shares the current among the remaining units. The system continuously outputs DC power to ensure stable operation of the plasma generator.

[0076] Because the rectifier unit uses active PFC technology, the power factor can be improved to over 0.99, the input harmonic content is significantly reduced, and there is no pollution to the power grid. Simultaneously, the full-bridge LLC resonant soft-switching technology is adopted to achieve zero-voltage turn-on and zero-current turn-off of the switching transistors, resulting in extremely low switching losses and an overall conversion efficiency of over 96%, demonstrating significant energy savings. High output power quality: Dedicated filter circuits are configured on the input side, bus side, and output side, resulting in low output voltage ripple and high DC purity. This provides a stable and clean DC power supply to the plasma generator, improving ignition success rate and arc stability.

[0077] In other embodiments, to optimize the busbar layout and heat dissipation channel design, reduce heat dissipation obstruction, and utilize high-efficiency soft-switching technology to reduce heat generation, the device exhibits low temperature rise, long service life of key components, and high long-term operational stability. (Refer to...) Figure 5 and Figure 6 As shown, the rectifier unit 3 is preferably installed on the left side of the cabinet, arranged vertically side by side; the chopper unit 5 is preferably installed on the right side of the cabinet, arranged vertically side by side; the front-end processing unit 1 is located in the lower left corner of the cabinet; and the control unit 7 is installed on the mounting plate at the top of the cabinet. The installation of the AC busbar 2, DC busbar 4, and output busbar 6 can be referenced. Figure 6 In some embodiments, alternative installation methods may be used.

[0078] This application also provides a digital rectifier cabinet control method, which can be applied to the digital rectifier cabinet described in the above embodiments. The method includes:

[0079] The control unit collects the operating status of each rectifier unit and each chopper unit and performs load balancing power distribution.

[0080] When the control unit detects a rectifier unit failure, it takes the failed rectifier unit offline and redistributes the load evenly among the remaining rectifier units.

[0081] When the control unit detects a chopper unit failure, it takes the failed chopper unit offline and redistributes the load of the remaining chopper units.

[0082] Specifically, refer to Figure 7 As shown, it may specifically include the following steps:

[0083] Step S1: Power on the control unit to initialize, complete the status detection of all rectifier units and chopper units, and confirm the number and working status of online units.

[0084] Step S2: The control unit performs load balancing on all online rectifier units according to the total output demand, so that the output power of each rectifier unit is consistent and does not exceed the rated operating range.

[0085] Step S3: The control unit collects the voltage, current, temperature and fault signals of each rectifier unit in real time and continuously judges whether a fault has occurred.

[0086] Step S4: If any rectifier unit is detected to be faulty, the control unit immediately issues a control command to take the faulty rectifier unit offline and recalculates the load distribution strategy to distribute the power evenly to the remaining normal rectifier units, thereby maintaining the DC bus voltage stability.

[0087] Step S5: The control unit performs load balancing on all online chopper units according to the total output demand, so that the output power of each chopper unit is consistent and does not exceed the rated operating range.

[0088] Step S6: The control unit collects the output voltage, output current and fault signals of each chopper unit in real time and continuously judges whether a fault has occurred.

[0089] Step S7: If any chopper unit is detected to be faulty, the control unit immediately issues a control command to take the faulty chopper unit offline and recalculates the load distribution strategy to distribute the power evenly to the remaining normal chopper units, so as to maintain a stable and continuous output DC power.

[0090] Step S8: During normal system operation, steps S2 to S7 are executed cyclically to achieve real-time load balancing, real-time fault monitoring, automatic offline operation of faulty units and automatic re-flow sharing of remaining units, ensuring that the system can still operate at reduced capacity under fault conditions.

[0091] As a specific application of the aforementioned digital rectifier cabinet, designed for a plasma ignition system of a large pulverized coal boiler, it features six rectifier units and six chopper units, resulting in improved output power and enhanced reliability.

[0092] The six rectifier units are fully connected in parallel through redundant parallel components, and adopt a three-phase rectification, active PFC, full-bridge LLC soft-switching structure to output a stable DC bus voltage with constant voltage.

[0093] The six chopper units are fully connected in parallel through redundant parallel components, and adopt a multi-bridge arm IGBT structure, LC output filtering, and constant current / constant power output.

[0094] The control unit adopts high-speed digital control and executes the control method described in the above embodiments to achieve six-level current sharing, six-level fault offline, and six-level derating operation. Even if any one to three units fail, the system can still operate normally, meeting the extremely high reliability requirements of industrial sites.

[0095] This embodiment adds input surge protection circuit, output reverse current protection circuit, insulation monitoring circuit, and remote communication interface, supporting remote monitoring, remote parameter setting, and remote fault alarm by the host computer, fully meeting the access requirements of the automated control system of thermal power plants. The DC busbar and output busbar are made of copper with an increased cross-sectional area to reduce conduction losses and temperature rise; the cabinet adopts a dustproof, oil-proof, and corrosion-proof design to adapt to the harsh environment of power plants.

[0096] This embodiment has been verified through long-term operation in industrial fields. The power factor is stable above 0.99, the efficiency is stable above 96%, the output ripple is small, the operation is stable and reliable, the downtime without failure is significantly reduced, and the maintenance workload is greatly reduced. It fully meets the requirements for long-term stable operation of large plasma ignition systems.

[0097] This application also provides a computer program product including computer-readable instructions, which, when executed on an electronic device, cause the electronic device to implement any of the digital rectifier cabinet control methods provided in this application.

[0098] This application also provides a computer-readable storage medium carrying one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can implement any of the digital rectifier cabinet control methods provided in this application.

[0099] It should also be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. In addition, in the device embodiment drawings provided in this application, the connection relationship between modules indicates that they have a communication connection, which can be implemented as one or more communication buses or signal lines.

[0100] Through the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary general-purpose hardware, or it can be implemented by special-purpose hardware including application-specific integrated circuits, special-purpose CPUs, special-purpose memory, special-purpose components, etc. Generally, any function performed by a computer program can be easily implemented by corresponding hardware, and the specific hardware structure used to implement the same function can be diverse, such as analog circuits, digital circuits, or special-purpose circuits. However, for this application, software program implementation is more often the preferred implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a readable storage medium, such as a computer floppy disk, USB flash drive, mobile hard disk, ROM, RAM, magnetic disk, or optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, training equipment, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0101] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product.

[0102] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions may be transmitted from one website, computer, training device, or data center to another website, computer, training device, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can store or a data storage device such as a training device or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state drives (SSDs)).

Claims

1. A digital rectifier cabinet, characterized in that, include: Rectifier unit, chopper unit, and control unit; The rectifier unit comprises at least two units, and each rectifier unit is connected in parallel with each other through a first parallel component, for converting three-phase AC power into DC power and outputting it to the DC bus. The chopper unit comprises at least two units, and each chopper unit is connected in parallel to the others through a second parallel component. The input terminal of the chopper unit is connected to the DC bus and is used to chop and transform the DC power to output controllable DC power. The control unit is electrically connected to each of the rectifier units and each of the chopper units. The control unit is used to perform load balancing distribution on each of the rectifier units and each of the chopper units, and to control the corresponding faulty unit to go offline when a fault is detected, so as to keep the remaining units running normally.

2. The digital rectifier cabinet according to claim 1, characterized in that, The rectifier unit includes: a three-phase rectifier circuit, a PFC module, a full-bridge LLC resonant converter module, and an input filter capacitor; The three-phase rectifier circuit is connected to the three-phase AC power supply, and the input filter capacitor is connected to the three-phase rectifier circuit to filter out input voltage ripple. The PFC module is connected to the output terminal of the three-phase rectifier circuit, and the full-bridge LLC resonant converter module is connected to the output terminal of the PFC module and outputs DC power to the DC bus.

3. The digital rectifier cabinet according to claim 2, characterized in that, The three-phase rectifier circuit includes an L1 rectifier bridge and an L2 rectifier bridge; the PFC module includes a PFC switch and a freewheeling diode; the full-bridge LLC resonant converter module includes a full-bridge switch, an LLC resonant network, and a high-frequency transformer.

4. The digital rectifier cabinet according to claim 1, characterized in that, The rectifier unit is configured to output in constant voltage mode to provide a stable DC bus voltage for the chopper unit.

5. The digital rectifier cabinet according to claim 1, characterized in that, The chopper unit includes: a bridge arm module composed of multiple sets of switching devices and an output filtering module; The bridge arm module is connected to the DC bus, and the output filter module is connected to the output terminal of the bridge arm module to smooth the output voltage.

6. The digital rectifier cabinet according to claim 5, characterized in that, The bridge arm module includes: two sets of four-bridge arm structures, each set of bridge arms contains three series-connected switching devices, which are MOSFETs or IGBTs; The output filtering module includes an inductor, an electrolytic capacitor, and a bleeder resistor, forming an LC low-pass filter circuit.

7. The digital rectifier cabinet according to claim 1, characterized in that, The chopper unit is controlled by a digital high-frequency switch and is configured to output controllable DC power in constant current or constant power mode.

8. The digital rectifier cabinet according to claim 1, characterized in that, Both the first parallel component and the second parallel component are redundant parallel structures, so that if a single rectifier unit or chopper unit fails and goes offline, the remaining units can be used to re-share current and operate at reduced capacity.

9. The digital rectifier cabinet according to claim 1, characterized in that, The rectifier unit also includes an output-side filter capacitor connected to the output terminal of the full-bridge LLC resonant converter module, used to filter out DC bus voltage ripple.

10. A digital rectifier cabinet control method, characterized in that, Applied to the digital rectifier cabinet of claim 1, the method includes: The control unit collects the operating status of each rectifier unit and each chopper unit and performs load balancing power distribution. When the control unit detects a rectifier unit failure, it controls the failed rectifier unit to go offline and redistributes the load of the remaining rectifier units. When the control unit detects a chopper unit failure, it takes the failed chopper unit offline and redistributes the load of the remaining chopper units.

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