Cascaded medium-voltage direct-hanging type bus voltage stabilization method and device and medium

Abstract

The invention discloses a cascaded medium-voltage direct-hanging type bus voltage stabilization method and device and a medium, and is applied to the field of power electronics. The method comprises the steps that the voltage level of a direct-current bus is monitored, the voltage value of the direct-current bus is obtained, and the voltage value of the direct-current bus is compared with a preset safety threshold value range; and when the voltage of the direct-current bus exceeds a safety threshold range, the plurality of independent charging and discharging circuits are controlled to charge or discharge. According to the invention, by adopting a modular design and a branch voltage division strategy, forward charging voltage stabilization and reverse supporting voltage stabilization are carried out on the direct current bus through charging or discharging of the charging and discharging circuit, stable adjustment of the voltage of the off-grid direct current bus is realized, and thus the electric energy quality and the power supply reliability of a power system are improved.

Description

Technical Field

[0001] The invention relates to the field of power electronics, and in particular to a cascaded medium-voltage direct-hanging busbar voltage stabilization method, device and medium. Background Art

[0002] With the massive integration of distributed generation resources and renewable energy, the voltage stability of power systems without the support of large power grids has become an increasingly severe technical challenge. In the off-grid local consumption system of renewable energy, the DC bus is an important link connecting multiple power electronic devices and loads, and its voltage stability is crucial to the performance of the entire power system.

[0003] Traditional voltage stabilization methods are mostly targeted at grid-connected systems, such as using passive filters and simple voltage stabilizers, while the power supply of off-grid systems is mainly independent power generation equipment, such as small solar photovoltaic systems, small wind turbines or diesel generators. The output characteristics of these power supplies are very different from those of large power grids. Taking solar photovoltaic systems as an example, their output power is strongly affected by factors such as light intensity and temperature. Changes in light intensity will cause large changes in the output voltage and current of photovoltaic cells, and this change may be frequent and large, so it is difficult to achieve DC bus voltage stability in off-grid systems.

[0004] It can be seen that how to stabilize the voltage fluctuation of the DC bus in the off-grid local consumption system of renewable energy is a technical problem that needs to be solved urgently by people in this field. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a cascaded medium-voltage direct-hanging busbar voltage stabilization method, device and medium, which solves the voltage fluctuation problem of the DC busbar in the off-grid local consumption system of renewable energy. The specific scheme is as follows:

[0006] In a first aspect, the present application provides a cascaded medium voltage direct-mounted busbar voltage stabilization method, wherein the cascaded medium voltage direct-mounted busbar voltage stabilization circuit comprises: a resistor arranged between a DC busbar positive input terminal and a DC busbar negative input terminal and a plurality of series-connected charging and discharging circuits; the method comprises:

[0007] Monitoring the voltage value of the DC bus;

[0008] Acquiring a voltage value of the DC bus and comparing the voltage value of the DC bus with a preset safety threshold range;

[0009] When the voltage of the DC bus exceeds a safety threshold range, controlling multiple independent charging and discharging circuits to charge;

[0010] When the voltage of the DC bus does not reach a safety threshold range, multiple independent charging and discharging circuits are controlled to charge and discharge.

[0011] Optionally, the plurality of charging and discharging circuits connected in series are connected in parallel with the resistor as a whole,

[0012] The charging and discharging circuit includes: a controller, a bypass switch, a super capacitor, an inductor, a voltage sensor and a DC-DC circuit;

[0013] The first end of the bypass switch is connected to the first end of the DC-DC circuit, and the common end of the two serves as the first end of the charge-discharge circuit;

[0014] The second end of the bypass switch is connected to the second end of the DC-DC circuit, and the common end of the two serves as the second end of the charge-discharge circuit;

[0015] The inductor is connected in series with the supercapacitor and then connected to the DC-DC circuit;

[0016] The voltage sensor is connected in parallel with the bypass switch and is used to measure the voltage value of the charge and discharge circuit;

[0017] The controller is connected to the voltage sensor through an isolation circuit, and is used to collect the voltage value of the charge and discharge circuit measured by the voltage sensor, and transmit the voltage value to the CPU;

[0018] One end of the charge-discharge circuit is connected to another charge-discharge circuit, and the series-connected charge-discharge circuits jointly divide the total voltage of the resistor.

[0019] Optional, including:

[0020] Obtaining the voltage value of the corresponding charging and discharging circuit collected by each controller;

[0021] Determining the charging and discharging parameters of each charging and discharging circuit according to the relationship between the voltage value of the DC bus and the safety threshold;

[0022] When the charging and discharging parameter indicates that the voltage of the DC bus exceeds a safety threshold range, controlling multiple independent charging and discharging circuits to charge;

[0023] When the charging and discharging parameters indicate that the voltage of the DC bus has not reached a safety threshold range, multiple independent charging and discharging circuits are controlled to charge and discharge.

[0024] Optionally, the cascaded medium-voltage direct-mounted busbar voltage stabilization circuit also includes: a backup charging and discharging circuit.

[0025] Optionally, also include:

[0026] detecting a fault signal sent by the controller and used to indicate that a fault has occurred in the corresponding charging and discharging circuit;

[0027] When the fault signal is detected, the corresponding charging and discharging circuit is controlled to be cut off from the cascaded medium-voltage direct-hanging busbar voltage stabilization circuit, and the standby charging and discharging circuit is controlled to be put into the cascaded medium-voltage direct-hanging busbar voltage stabilization circuit.

[0028] Optionally, the DC-DC circuit includes: a voltage-equalizing resistor, a support capacitor, an IGBT, an absorption capacitor and a diode;

[0029] The first end of the voltage balancing resistor, the first end of the support capacitor, the first end of the IGBT, and the first end of the absorption capacitor are connected to the positive input end of the DC-DC circuit;

[0030] The second end of the IGBT is connected to the cathode of the diode;

[0031] The control end of the IGBT is connected to the output end of the controller;

[0032] The second end of the voltage balancing resistor, the second end of the supporting capacitor, and the anode of the diode are connected to the negative input end of the DC-DC circuit.

[0033] Optionally, the monitoring of the voltage value of the DC bus includes:

[0034] Obtaining a voltage value of a voltage sensor in the charge and discharge circuit;

[0035] The voltage value of the DC bus is determined based on the voltage values ​​of the voltage sensors in each charging and discharging circuit.

[0036] Optionally, the cascaded medium voltage direct-mounted busbar voltage stabilization circuit further includes a voltage stabilization device feed protection cabinet disposed on the DC busbar, and the method further includes:

[0037] Acquiring a current value of the current sensor;

[0038] When the current value of the current sensor is greater than the current threshold, the voltage stabilizing device feeding protection cabinet is disconnected.

[0039] In a second aspect, the present application provides a communication network control device, comprising:

[0040] A central controller, used for receiving a signal representing the voltage of the DC bus collected by the controller and issuing a control instruction to the bypass switch and the controller based on the signal representing the voltage of the DC bus, so as to implement the cascaded medium-voltage direct-hanging bus voltage stabilization method;

[0041] The industrial computer is used to receive, store and display the signal representing the voltage of the DC bus.

[0042] In a third aspect, the present application provides a computer-readable storage medium for storing a computer program; wherein, when the computer program is executed by a processor, the cascaded medium-voltage direct-hanging busbar voltage stabilization method is implemented.

[0043] It can be seen that the present application monitors the voltage level of the DC bus, obtains the voltage value of the DC bus and compares the voltage value of the DC bus with a preset safety threshold range; when the voltage of the DC bus exceeds the safety threshold range, multiple independent charging and discharging circuits are controlled to charge or discharge. The present application adopts a modular design and branch voltage division strategy, and performs forward charging and reverse support voltage stabilization on the DC bus through charging or discharging of the charging and discharging circuit, thereby achieving stable regulation of the off-grid DC bus voltage, thereby improving the power quality and power supply reliability of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0045] Figure 1 A flow chart of a cascaded medium-voltage direct-hanging busbar voltage stabilization method disclosed in this application;

[0046] Figure 2 A cascaded medium voltage direct-hanging busbar voltage stabilization circuit diagram disclosed in this application;

[0047] Figure 3 A DC-DC circuit diagram disclosed in this application;

[0048] Figure 4 A flow chart of a cascaded medium-voltage direct-hanging busbar voltage stabilization method disclosed in this application;

[0049] Figure 5 This is a schematic diagram of the structure of a communication network control device disclosed in this application. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] The core of this application is to provide a cascaded medium-voltage direct-hanging busbar voltage stabilization method.

[0052] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0053] With the massive integration of distributed generation resources and renewable energy, the voltage stability of power systems without the support of large power grids has become an increasingly severe technical challenge. In the off-grid local consumption system of renewable energy, the DC bus is an important link connecting multiple power electronic devices and loads, and its voltage stability is crucial to the performance of the entire power system.

[0054] Traditional voltage stabilization methods are mostly targeted at grid-connected systems, such as using passive filters and simple voltage stabilizers, while the power supply of off-grid systems is mainly independent power generation equipment, such as small solar photovoltaic systems, small wind turbines or diesel generators. The output characteristics of these power supplies are very different from those of large power grids. Taking solar photovoltaic systems as an example, their output power is strongly affected by factors such as light intensity and temperature. Changes in light intensity will cause large changes in the output voltage and current of photovoltaic cells, and this change may be frequent and large, so it is difficult to achieve DC bus voltage stability in off-grid systems.

[0055] It can be seen that how to stabilize the voltage fluctuation of the DC bus in the off-grid local consumption system of renewable energy is a technical problem that needs to be solved urgently by people in this field.

[0056] See also Figure 1 As shown, in order to solve the above problems, an embodiment of the present invention discloses a cascaded medium voltage direct-hanging busbar voltage stabilization method, which may include:

[0057] Step S11, monitoring the voltage value of the DC bus.

[0058] In this embodiment, real-time monitoring of bus voltage and current can be achieved through voltage sensors. Since the cascaded medium-voltage direct-mounted bus voltage stabilization circuit contains many charging and discharging circuits, voltage collection is set on the branches of each charging and discharging circuit and other key nodes of the DC bus, and the collected voltage values ​​are sorted and preliminarily processed before being transmitted to the CPU of the control system. The CPU can simultaneously receive data from controllers at different locations to ensure comprehensive monitoring of the entire DC bus voltage.

[0059] In a specific implementation, this embodiment provides a cascaded medium voltage direct-mounted busbar voltage stabilizing circuit. Figure 2 As shown, the resistor and multiple series-connected charging and discharging circuits are arranged between the positive input terminal of the DC bus and the negative input terminal of the DC bus. The multiple series-connected charging and discharging circuits are connected in parallel with the resistor as a whole.

[0060] The charging and discharging circuit includes: a controller, a bypass switch, a super capacitor, an inductor, a voltage sensor and a DC-DC circuit;

[0061] The first end of the bypass switch is connected to the first end of the DC-DC circuit, and the common end of the two serves as the first end of the charge-discharge circuit;

[0062] The second end of the bypass switch is connected to the second end of the DC-DC circuit, and the common end of the two serves as the second end of the charge-discharge circuit;

[0063] The inductor and supercapacitor are connected in series and then connected to the DC-DC circuit;

[0064] The voltage sensor is connected in parallel with the bypass switch and is used to measure the voltage value of the charging and discharging circuit;

[0065] The controller is connected to the voltage sensor through an isolation circuit, and is used to collect the voltage value of the charge and discharge circuit measured by the voltage sensor, and transmit the voltage value to the CPU;

[0066] One end of the charge and discharge circuit is connected to another charge and discharge circuit, and the series-connected charge and discharge circuits share the total voltage of the voltage-dividing resistor.

[0067] The resistors and multiple series-connected charging and discharging circuits are set between the positive input terminal of the DC bus and the negative input terminal of the DC bus. The resistors divide the DC bus voltage for the first time. The resistors are usually an even number. The bus midpoint voltage position is set between half of the series-connected resistors and the other half of the series resistors. The charging and discharging circuits further divide the voltage of the module after the resistor voltage division. Figure 1 As shown, the bypass switch is the key to connect the charging and discharging circuit between the positive and negative input terminals of the DC bus. When the bypass switch is closed, the charging and discharging circuit is short-circuited. When the bypass switch is opened, the charging and discharging circuit corresponding to the bypass switch is connected between the positive and negative poles of the DC bus.

[0068] As can be seen from the figure, the controller is connected in parallel with the bypass switch to collect the voltage value of the corresponding charging and discharging circuit and transmit it to the central processing unit (CPU). It can be understood that the controller itself also has judgment and decision-making capabilities.

[0069] Step S12: Acquire the voltage value of the DC bus and compare the voltage value of the DC bus with a preset safety threshold range.

[0070] In this embodiment, monitoring the voltage value of the DC bus includes: acquiring the voltage value of the voltage sensor in the charging and discharging circuit; and determining the voltage value of the DC bus based on the voltage value of the voltage sensor in each charging and discharging circuit.

[0071] After obtaining the total voltage value of the DC bus and the voltage value allocated by the DC bus to each charging and discharging circuit, the total voltage value of the DC bus is compared with the preset DC bus total voltage safety threshold range; the voltage value allocated by the DC bus to each charging and discharging circuit is compared with the voltage safety threshold range of each charging and discharging circuit.

[0072] In this embodiment, each charging and discharging circuit determines whether the voltage value of each charging and discharging circuit is within a safe range according to the relationship between the voltage value of the DC bus and the safety threshold.

[0073] In a specific implementation, the controller determines the charge and discharge parameters of each charge and discharge circuit according to the relationship between the voltage value of the DC bus and the safety threshold, and the charge and discharge parameters characterize the relationship between the voltage of the DC bus and the safety threshold range. The result of comparing the total voltage value of the DC bus with the preset DC bus total voltage safety threshold range and the charge and discharge parameters characterizing whether the voltage of each charge and discharge circuit exceeds the safety threshold range will be transmitted to the CPU at the same time. This facilitates the subsequent CPU to issue voltage stabilization instructions to the charge and discharge circuit and / or the DC bus, that is, when the voltage value of the DC bus exceeds or is lower than the normal operating threshold range of the voltage, the CPU will control the switching of the charge and discharge circuit.

[0074] Step S13: When the voltage of the DC bus exceeds a safety threshold range, control multiple independent charging and discharging circuits to charge.

[0075] In this embodiment, the safety threshold range of the DC bus voltage is pre-set in the CPU of the control system according to the requirements of the electrical equipment. When the CPU receives the DC bus voltage value from the controller, it immediately compares it with the preset safety threshold range. If the current DC bus voltage value is greater than the safety threshold range, it means that the DC bus voltage is too high, which may cause damage to the connected equipment. At this time, the DC bus is controlled to charge the charging and discharging circuit to absorb the overvoltage of the DC bus.

[0076] In a specific implementation, this embodiment provides a DC-DC circuit such as Figure 3 As shown, including:

[0077] Voltage grading resistors, support capacitors, IGBTs, absorption capacitors and diodes;

[0078] The first end of the voltage balancing resistor, the first end of the supporting capacitor, the first end of the IGBT, and the first end of the absorption capacitor are connected to the positive input end of the DC-DC circuit;

[0079] The second terminal of the IGBT is connected to the cathode of the diode;

[0080] The control end of the IGBT is connected to the output end of the controller;

[0081] The second end of the voltage balancing resistor, the second end of the supporting capacitor, and the anode of the diode are connected to the negative input end of the DC-DC circuit.

[0082] In a specific implementation, the voltages theoretically divided by each charging and discharging circuit are the same, that is, the equalizing resistors have the same resistance value, which is used to ensure that the voltages at both ends of each component in the circuit are evenly distributed. When the DC bus voltage is high, the insulated gate bipolar transistor (IGBT) is turned on, and the electric energy is absorbed by the supercapacitor to reduce the voltage to achieve the voltage stabilization function. The support capacitor is mainly used to provide energy storage and release functions in the circuit. It can provide energy when a large current is needed instantly, smooth voltage fluctuations, and ensure that the voltage in the circuit is stable. During the charging process, the diode allows the current to flow in one direction and stores the electric energy in the capacitor or other energy storage element. During the discharge process, the diode prevents the current from flowing back, ensures that the electric energy flows in the designed direction, and protects other components in the circuit. The absorption capacitor is used to absorb high-frequency noise and spike voltage in the circuit. During the DC-DC conversion process, some high-frequency interference and voltage fluctuations may be generated. The absorption capacitor can filter out these interferences, make the output voltage smoother, and protect sensitive components in the circuit.

[0083] It is understandable that the controller determines the charging and discharging parameters of each charging and discharging circuit according to the relationship between the voltage value of the DC bus and the safety threshold. When the charging and discharging parameters indicate that the voltage of the DC bus exceeds the safety threshold range, multiple independent charging and discharging circuits are controlled to charge. At the same time, the CPU also sends a control signal to each independent charging and discharging circuit to start the charging mode. For example, the power module in the charging and discharging circuit uses high-frequency switching power supply technology to convert the medium-voltage DC power supply into a suitable low-voltage DC voltage to charge the supercapacitor in a safe and efficient manner. During the charging process, by controlling the switching frequency and duty cycle of the power module, the size of the charging current can be accurately adjusted to avoid the impact of excessive charging current on the supercapacitor and the system. As the supercapacitor is charged, the supercapacitor absorbs excess electrical energy from the DC bus, thereby gradually reducing the voltage of the DC bus. During the charging process, the CPU continuously monitors the voltage changes of the DC bus and dynamically adjusts the charging power of each charging and discharging circuit according to the rate and amplitude of the voltage drop. For example, if it is found that the voltage drops too fast, the charging power may be appropriately reduced to achieve smooth voltage regulation.

[0084] Step S14: When the voltage of the DC bus does not reach the safety threshold range, control the multiple independent charging and discharging circuits to charge and discharge.

[0085] If the voltage value is less than the safety threshold range, it indicates that the voltage is too low, which may affect the normal operating efficiency of the equipment.

[0086] In a specific implementation, the controller determines the charge and discharge parameters of each charge and discharge circuit based on the relationship between the voltage value of the DC bus and the safety threshold. When the charge and discharge parameters indicate that the voltage of the DC bus does not reach the safety threshold range, the controller controls multiple independent charge and discharge circuits to charge and discharge.

[0087] At the same time, the CPU also sends control signals to multiple independent charging and discharging circuits, causing some of the charging and discharging circuits to enter the discharge mode, while others continue to charge. The specific charging and discharging branches are flexibly allocated according to the system control strategy and the current status of each charging and discharging circuit. The supercapacitors in the charging and discharging circuits that enter the discharge mode begin to release electrical energy to the DC bus to supplement the voltage of the DC bus. For example, by controlling the switching elements in the power module in the charging and discharging circuit, the electrical energy stored in the supercapacitor is inverted into medium-voltage DC energy and injected into the DC bus.

[0088] It is understandable that supercapacitors can obtain electrical energy from an external power source or output electrical energy to the outside according to a certain strategy to prepare for subsequent voltage regulation. In terms of component selection, the parameter configuration of the supercapacitor can also refer to the fluctuation range of the DC bus voltage in the past to select a suitable configuration. In this process, the CPU pays close attention to the voltage recovery of the DC bus and the working status of each charging and discharging circuit to ensure that the voltage can stably rise to the safety threshold range, and that the supercapacitors of each charging and discharging circuit will not be overcharged or over-discharged. By continuously adjusting the charging and discharging state of the charging and discharging circuit, the voltage of the DC bus is always maintained within the set safety threshold range.

[0089] It is understandable that during the entire voltage stabilization process, an alarm module is added to the main circuit of the bus or the main branch circuit, which has the function of fault detection and alarm. If a certain charging and discharging circuit fails, such as power module damage, energy storage capacitor leakage, etc., the control system can detect the fault information in time and send out an alarm signal, while adjusting the working status of other normal charging and discharging circuits to maintain the voltage stability of the DC bus as much as possible, waiting for maintenance personnel to repair the fault.

[0090] It can be seen that the embodiment of the present application monitors the voltage level of the DC bus, obtains the voltage value of the DC bus and compares the voltage value of the DC bus with a preset safety threshold range; when the voltage of the DC bus exceeds the safety threshold range, multiple independent charging and discharging circuits are controlled to charge or discharge. The present application adopts a modular design and a branch voltage division strategy, and performs forward charging and voltage stabilization and reverse support voltage stabilization on the DC bus through charging or discharging of the charging and discharging circuit, thereby achieving stable regulation of the off-grid DC bus voltage, thereby improving the power quality and power supply reliability of the power system.

[0091] See also Figure 4As shown, in order to further improve the reliability of the voltage stabilization circuit, the embodiment of the present application provides a cascaded medium voltage direct-mounted busbar voltage stabilization method, which may include:

[0092] Step S21, obtaining the voltage value of the corresponding charging and discharging circuit collected by each controller, and detecting a fault signal used to indicate that a fault occurs in the corresponding charging and discharging circuit;

[0093] When the voltage value of the corresponding charge-discharge circuit collected by the controller exceeds the threshold range when the charge-discharge circuit is working normally, it means that the charge-discharge circuit is faulty. At this time, the charge-discharge circuit cannot realize the function of the charge-discharge circuit, that is, it does not have the ability to stabilize voltage. At this time, the controller will collect the fault signal indicating that the charge-discharge circuit is faulty and transmit the fault signal to the CPU.

[0094] Step S22: When a fault signal is detected, the corresponding charging and discharging circuit is controlled to be cut off from the cascaded medium-voltage direct-mounted busbar voltage stabilization circuit, and the standby charging and discharging circuit is controlled to be put into the cascaded medium-voltage direct-mounted busbar voltage stabilization circuit.

[0095] When a fault signal is detected, the controller of the faulty charging and discharging circuit will control the bypass switch of the branch to disconnect to prevent the faulty charging and discharging circuit from causing further adverse effects on the mainstream bus voltage. At the same time, the CPU sends a control instruction to the standby charging and discharging circuit controller, and the standby charging and discharging circuit controller controls the bypass switch of the standby charging and discharging circuit to disconnect. The standby charging and discharging circuit is put into the cascaded medium-voltage direct-hanging bus voltage stabilizing circuit to replace the faulty charging and discharging circuit, thereby eliminating the impact of the charging and discharging circuit fault on the mainstream bus voltage.

[0096] It can be seen that in this embodiment, by preparing a redundant strategy for backup charging and discharging circuits, the fault tolerance of the cascaded medium-voltage direct-mounted busbar voltage stabilization circuit is improved. When there is a faulty charging and discharging circuit, the fault can be discovered and eliminated in time, thereby improving the reliability of the cascaded medium-voltage direct-mounted busbar voltage stabilization circuit.

[0097] According to the above embodiment, this embodiment provides a specific solution, the cascaded medium voltage direct-hanging busbar voltage stabilization circuit also includes a voltage stabilization device feeding protection cabinet arranged on the DC busbar, and the method also includes: obtaining a current value of a current sensor;

[0098] When the current value of the current sensor is greater than the current threshold, the voltage stabilizing device feeding protection cabinet is disconnected.

[0099] The current sensor is set on the DC bus trunk to measure the total current of the DC bus and transmit the acquired DC bus current value data to the CPU. A threshold range corresponding to the current value of the DC bus is set inside the CPU. When the current value exceeds or exceeds the normal working threshold range, there is a risk of short circuit in the DC bus. At this time, the voltage stabilizer feed protection cabinet is disconnected to ensure the safety of the electrical components on the DC bus.

[0100] See also Figure 5 In order to monitor the DC bus data more timely and accurately, the present application further provides a communication network control device, such as Figure 5 As shown, the CPU and the controller communicate through optical fiber. The controller transmits the collected voltage and temperature signals to the CPU through optical fiber. The CPU is connected to the electrical port switch through Ethernet. The PLC and industrial computer are also connected to the electrical port switch through Ethernet. The CPU, PLC, and industrial computer communicate with each other through the electrical port switch. The CPU transmits the signals collected by the controller to the industrial computer, and displays and stores them on the industrial computer; the signals collected by the PLC and the digital signals output to the outside will also be displayed and stored on the industrial computer. The device's external communication is realized through two communication modules. The data and other information collected by the CPU and PLC are transmitted to the optical port switch through the two communication modules of the PLC in different network segments to realize communication with the upper management system and form the communication network of the device. The communication network has the following functions.

[0101] Signal acquisition: The controller collects the voltage signal of each branch, the status signal of each branch bypass switch, the negative temperature coefficient (NTC) signal of each IGBT module, and the temperature signal; the CPU collects the medium voltage signal and the main circuit current signal; the programmable logic controller (PLC) collects the signal of the voltage stabilizing device feed protection cabinet, and the collected signals are transmitted to the industrial computer via Ethernet for display and storage.

[0102] Device control: The CPU and controller communicate through optical fiber, and the controller and driver board communicate through optical fiber. The pulse width modulation (PWM) control signal of IGBT on and off is sent through optical fiber to control the on and off of IGBT. The controller has digital signal acquisition and digital signal output functions, and can control the closing and opening of the bypass contactor through the intermediate relay.

[0103] Fault recording: When a fault occurs in the device, the controller and the CPU itself have the function of collecting data. After collecting the data generated during the fault, they are transmitted to the industrial computer, and through image processing, the corresponding voltage and current waveforms during the fault are generated. The data and waveforms are stored, and the time when the data and waveforms are generated is recorded to facilitate subsequent research and analysis of the fault information. The data can also be communicated to the upper-level management system through the optical port switch. The industrial computer itself has the function of storing and exporting data, and can extract data and record it on-site.

[0104] Furthermore, the present application also discloses a computer-readable storage medium for storing a computer program; wherein the computer program, when executed by a processor, implements the aforementioned disclosed virtual machine data migration method. For the specific steps of the method, reference may be made to the corresponding contents disclosed in the aforementioned embodiments, and no further description will be given here.

[0105] The above is a detailed introduction to a cascaded medium-voltage direct-hanging busbar voltage stabilization method, device and medium provided by the present application. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the embodiments can be referenced to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

[0106] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0107] The technical solution provided by the present application is introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for general technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A cascaded medium voltage direct-hanging busbar voltage stabilization method, characterized in that: The cascaded medium voltage direct-mounted busbar voltage stabilization circuit comprises: a resistor arranged between a DC busbar positive input terminal and a DC busbar negative input terminal and a plurality of charging and discharging circuits connected in series; the method comprises: Monitoring the voltage value of the DC bus; Acquiring a voltage value of the DC bus and comparing the voltage value of the DC bus with a preset safety threshold range; When the voltage of the DC bus exceeds a safety threshold range, controlling multiple independent charging and discharging circuits to charge; When the voltage of the DC bus does not reach a safety threshold range, multiple independent charging and discharging circuits are controlled to charge and discharge.

2. The cascaded medium voltage direct-hanging busbar voltage stabilization method according to claim 1 is characterized in that: The multiple series-connected charging and discharging circuits are connected in parallel with the resistor as a whole, and the charging and discharging circuit includes: a controller, a bypass switch, a super capacitor, an inductor, a voltage sensor and a DC-DC circuit; The first end of the bypass switch is connected to the first end of the DC-DC circuit, and the common end of the two serves as the first end of the charge-discharge circuit; The second end of the bypass switch is connected to the second end of the DC-DC circuit, and the common end of the two serves as the second end of the charge-discharge circuit; The inductor is connected in series with the supercapacitor and then connected to the DC-DC circuit; The voltage sensor is connected in parallel with the bypass switch and is used to measure the voltage value of the charge and discharge circuit; The controller is connected to the voltage sensor through an isolation circuit, and is used to collect the voltage value of the charge and discharge circuit measured by the voltage sensor, and transmit the voltage value to the CPU; One end of the charge-discharge circuit is connected to another charge-discharge circuit, and the series-connected charge-discharge circuits jointly divide the total voltage of the resistor.

3. The cascaded medium voltage direct-hanging busbar voltage stabilization method according to claim 2 is characterized in that: include: Obtaining the voltage value of the corresponding charging and discharging circuit collected by each controller; Determining the charging and discharging parameters of each charging and discharging circuit according to the relationship between the voltage value of the DC bus and the safety threshold; When the charging and discharging parameter indicates that the voltage of the DC bus exceeds a safety threshold range, controlling multiple independent charging and discharging circuits to charge; When the charging and discharging parameters indicate that the voltage of the DC bus has not reached a safety threshold range, multiple independent charging and discharging circuits are controlled to charge and discharge.

4. The cascaded medium voltage direct-hanging busbar voltage stabilization method according to claim 2 is characterized in that: The cascaded medium-voltage direct-hanging busbar voltage stabilizing circuit also includes: a standby charging and discharging circuit.

5. The cascaded medium voltage direct-hanging busbar voltage stabilization method according to claim 4 is characterized in that: Also includes: detecting a fault signal sent by the controller and used to indicate that a fault has occurred in the corresponding charging and discharging circuit; When the fault signal is detected, the corresponding charging and discharging circuit is controlled to be cut off from the cascaded medium-voltage direct-hanging busbar voltage stabilization circuit, and the standby charging and discharging circuit is controlled to be put into the cascaded medium-voltage direct-hanging busbar voltage stabilization circuit.

6. The cascaded medium voltage direct-hanging busbar voltage stabilization method according to claim 2 is characterized in that: The DC-DC circuit includes: a voltage-equalizing resistor, a supporting capacitor, an IGBT, an absorption capacitor and a diode; The first end of the voltage balancing resistor, the first end of the support capacitor, the first end of the IGBT, and the first end of the absorption capacitor are connected to the positive input end of the DC-DC circuit; The second end of the IGBT is connected to the cathode of the diode; The control end of the IGBT is connected to the output end of the controller; The second end of the voltage balancing resistor, the second end of the supporting capacitor, and the anode of the diode are connected to the negative input end of the DC-DC circuit.

7. The cascaded medium voltage direct-hanging busbar voltage stabilization method according to claim 2 is characterized in that: The monitoring of the voltage value of the DC bus includes: Obtaining a voltage value of a voltage sensor in the charge and discharge circuit; The voltage value of the DC bus is determined based on the voltage values ​​of the voltage sensors in each charging and discharging circuit.

8. The cascaded medium voltage direct-hanging busbar voltage stabilization method according to any one of claims 1 to 7, characterized in that: The cascaded medium voltage direct-hanging busbar voltage stabilization circuit further includes a voltage stabilization device feed protection cabinet arranged on the DC busbar, and the method further includes: Acquiring a current value of the current sensor; When the current value of the current sensor is greater than the current threshold, the voltage stabilizing device feeding protection cabinet is disconnected.

9. A communication network control device, characterized in that: include: A central controller, used for receiving a signal representing the voltage of the DC bus collected by the controller and issuing control instructions to the bypass switch and the controller based on the signal representing the voltage of the DC bus, so as to implement the cascaded medium-voltage direct-mounted bus voltage stabilization method according to any one of claims 1 to 8; The industrial computer is used to receive, store and display the signal representing the voltage of the DC bus.

10. A computer-readable storage medium, characterized in that: Used to store computer programs; wherein, when the computer program is executed by a processor, it implements the cascaded medium-voltage direct-hanging busbar stabilization method as described in any one of claims 1 to 8.

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