Direct current bus voltage loss automatic switching system and compensation control method

Abstract

The invention relates to the technical field of voltage loss compensation, in particular to a direct current bus voltage loss automatic switching system and a compensation control method. The voltage adjusting unit is electrically connected with the protection filtering unit, the power correction unit, the coordination control unit, the safety conversion unit and the stable output unit. And the voltage adjusting unit adopts a parallel redundancy design. The output and input voltage constant machine core can output voltage to form a machine core output condition; the output voltage needs to be lower than the input voltage, otherwise, the system is in a hot standby state, and a blocking circuit opening condition is formed; and after voltage loss of one side of the given bus is given, the machine core outputs to the voltage loss side to form a blocking bridge conduction condition. The direct-current bus voltage can be automatically detected, automatic starting can be achieved when the voltage loss condition is detected, manual intervention is not needed, and delay and errors caused by manual operation are avoided. The device integrally ensures the stability of the DC bus voltage, improves the utilization rate of equipment, prolongs the service life of the equipment, reduces the manual maintenance workload through automatic operation, and reduces the maintenance cost.

Description

Technical Field

[0001] The invention relates to the technical field of voltage loss compensation, and in particular to a direct current bus voltage loss automatic switching system and a compensation control method. Background Art

[0002] In a substation, the DC system is the key to ensuring the normal operation of relay protection, control, signal and other equipment. Usually, a substation is equipped with two independent DC systems to ensure the reliability of power supply. However, in actual operation, there is still a risk of DC bus voltage loss. The main reason is that when a rectifier system fails, the system will be unable to provide DC power, which will cause the DC bus voltage to lose. Although batteries can provide backup power, if the battery capacity is insufficient, it may also cause the DC bus voltage to lose.

[0003] In order to solve the problem of DC bus voltage loss, the existing technology usually uses a bus tie switch to connect two DC systems. However, the existing solutions have the following limitations: the switching of the bus tie switch usually requires manual operation. If the operation is not timely, the DC bus voltage loss time may be too long, affecting the normal operation of the equipment. Manual operation of the bus tie switch requires consideration of many factors, such as system status, fault type, etc. The operation process is relatively complicated and prone to errors. The existing bus tie switch cannot automatically adjust according to the system status and cannot adapt to the dynamic changes in the operation of the DC system.

[0004] Therefore, a DC bus voltage loss automatic switching system and a compensation control method are needed to improve the reliability and safety of power grid operation. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract of the specification and the title of the invention of this application to avoid blurring the purpose of this section, the abstract of the specification and the title of the invention, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above-mentioned prior art, there is a risk of depressurization of the DC bus, and the switching of the busbar tie switch usually requires manual operation. Untimely operation may cause the DC bus to lose pressure for too long, affecting the normal operation of the equipment. The existing busbar tie switch cannot automatically adjust according to the system status and cannot adapt to the dynamic changes in the operation of the DC system.

[0007] Therefore, the technical problem to be solved by the present invention is to design a DC bus voltage loss automatic switching system and a compensation control method to improve the reliability and safety of power grid operation to meet the current environmental requirements.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: a DC bus voltage loss automatic switching system, comprising:

[0009] The voltage adjustment unit is electrically connected to include:

[0010] Protection filter unit, power correction unit, coordination control unit, safety conversion unit, stable output unit;

[0011] The voltage adjustment unit adopts a parallel redundant design.

[0012] A compensation control method, characterized in that:

[0013] The output and input voltages must be constant before the movement can output voltage, forming the output condition of the movement;

[0014] The output voltage must be lower than the input voltage, otherwise the system is in hot standby mode, forming the conditions for the DC blocking circuit to start;

[0015] When one side of a given bus loses pressure, the movement outputs to the side that loses pressure, forming the conduction condition of the direct-isolating bridge.

[0016] As an improvement of the present invention,

[0017] Movement output conditions, including,

[0018] Detect voltage through protection filter unit and stable output unit;

[0019] When the given voltage at the module output is higher than the module output voltage, the DC isolation bridge is cut off and the movement cannot output voltage.

[0020] As an improvement of the present invention,

[0021] Detect voltage through protection filter unit and stable output unit;

[0022] When the DC bus is given on both sides, the module input and output voltages are the same and the movement output starts.

[0023] As an improvement of the present invention,

[0024] DC blocking circuit start-up conditions include:

[0025] The output voltage of a single core must be set to be about 5V lower than its input voltage;

[0026] Based on the preset value, when the DC bus is given on both sides and the module input and output voltages are the same, the DC isolation circuits are all in the cut-off state, and the system is in the hot standby state;

[0027] After the voltage adjustment unit has completed adjusting the voltage, the DC isolation circuit is turned on.

[0028] As an improvement of the present invention, the invention comprises:

[0029] The conditions for the conduction of the DC isolation bridge include:

[0030] The DC-isolating bridge is arranged on the DC bus, and the DC-isolating bridge comprises at least one bidirectional conducting element and a matching trigger circuit;

[0031] When one side of a given bus loses voltage, the DC-isolating bridge opens, and the movement outputs voltage to the side losing voltage through the DC-isolating bridge for voltage compensation.

[0032] As an improvement of the present invention, the invention comprises:

[0033] Pre-set the trigger threshold value for a given busbar voltage loss;

[0034] When the DC bus voltage drops to the set value, the system starts, the DC isolation bridge opens, and the movement compensates the voltage on the voltage-losing side through the DC isolation bridge.

[0035] As an improvement of the present invention, it includes adjusting the system working state by coordinating the control unit to cause shutdown when receiving an external shutdown signal.

[0036] The beneficial effects of the present invention are: it can automatically detect the DC bus voltage and automatically start when a voltage loss is detected, without manual intervention, thus avoiding delays and errors caused by manual operation. The device as a whole ensures the stability of the DC bus voltage, improves the utilization rate of the equipment, and prolongs the service life of the equipment. The automated operation reduces the workload of manual maintenance and reduces maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0038] Figure 1 This is a circuit planning diagram of the DC bus voltage loss automatic switching system in the present invention.

[0039] Figure 2 The present invention is a flow chart of the compensation control method in the DC bus voltage loss automatic switching system. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0041] Example 1

[0042] Reference Figure 1 , this embodiment provides a DC bus voltage loss automatic switching system.

[0043] There are multiple modules in the voltage adjustment unit 100 , and the modules are electrically connected to each other, and together constitute the voltage adjustment unit 100 , which belongs to the entire circuit guide assembly.

[0044] The protection filter unit 200 can be an input protection and filtering circuit, which is located at the entrance of the entire circuit. When the voltage is too high, the current is too large, or a momentary high-voltage pulse occurs, the protection filter unit 200 can prevent adverse factors from damaging the electronic components inside the module, ensuring that the module is not damaged and can work stably. The power correction unit 300 can be a pre-stage PFC control circuit to help the power supply improve work efficiency, reduce unnecessary energy loss, and minimize the damage of power grid harmonics to the equipment.

[0045] The coordination control unit 400 may be a digital LLC controller, which adjusts the output voltage as required, optimizes the power conversion process, and reduces energy loss. The LLC controller ensures that the frequency of the safety conversion unit 500, that is, the LLC converter, remains stable. The LLC converter can convert one voltage into another voltage while ensuring that the conversion process is efficient and stable.

[0046] The stable output unit 600 may be an output filter and EMC circuit. The output filter circuit is like a sieve, which makes the output current more stable and smooth. The EMC circuit can help resist the interference of external electromagnetic waves.

[0047] The system includes a pair of DC power buses, which are defined as a positive bus (+DC Bus) and a negative bus (-DC Bus). They are the main trunks of the DC power system and are responsible for providing stable DC power to various electrical loads. The voltage adjustment unit 100 adopts a parallel redundant design to ensure that the system can continue to operate in the event of a single component failure.

[0048] Example 2

[0049] Reference Figure 1 This embodiment is based on the previous embodiment, and is different from the previous embodiment in that:

[0050] The protection filter unit 200 is externally connected to an input sampling circuit, which is usually used to sample and process input signals for subsequent control and analysis. The input sampling circuit is subsequently connected to the monitoring and adjustment unit 700, and the information data obtained by the input sampling circuit will enter the monitoring and adjustment unit 700.

[0051] The monitoring and regulating unit 700 includes sensors, processors and other related components to monitor the system status and adjust parameters or output control instructions as needed. The monitoring and regulating unit 700 obtains data through an input sampling circuit, and then analyzes and regulates it.

[0052] The coordination control unit 400 is one of the core controllers of the entire system. It makes decisions based on the data from the monitoring and regulation unit 700 and exchanges information with other modules through the front / back communication mechanism. The "front / back interactive communication" here refers to the communication between different levels in the control system to ensure overall performance and stability.

[0053] The monitoring and regulating unit 700 finally acts on the power correction unit 300 again to perform subsequent voltage adjustment.

[0054] Example 3

[0055] Reference Figures 1-2 This embodiment is based on the previous embodiment, and is different from the previous embodiment in that:

[0056] During the operation of the system, the protection filter unit 200 and the stable output unit 600 can continuously and stably detect the voltage in the entire circuit. The movement can only work normally when the actual output voltage is lower than the specified input voltage.

[0057] Before the movement can work normally, it is necessary to set the output voltage of the single movement to be about 5V lower than its input voltage. This step is to ensure the safety of the entire circuit and prevent short circuit failure.

[0058] The output voltage must be lower than the input voltage, otherwise the entire system will enter hot standby mode. Even if the movement can work normally, it still cannot output normally. At this time, the DC isolation circuit is disconnected, blocking the output voltage of the movement.

[0059] When the voltage adjustment unit 100 reduces the voltage to meet the set value through other connected units, the DC isolation circuit will be turned on, and the movement can output voltage normally in the subsequent process.

[0060] The DC blocking bridge circuit consists of four IGBT modules, each of which contains an IGBT switching element and a corresponding drive circuit. These IGBT modules are connected in the form of an H-bridge, which can achieve fast switching of the DC power supply under the control signal.

[0061] The voltage loss detection module includes a voltage sensor with an accuracy of 0.5%, which can monitor the bus voltage in real time and convert the voltage signal into an analog signal of 0-10V. During the operation of the system, the voltage loss detection module continuously monitors the bus voltage. Once it is detected that the bus voltage is lower than the set threshold, the voltage loss detection module immediately sends a low level signal to the coordination control unit 400.

[0062] After receiving the pressure loss signal, the coordination control unit 400 immediately starts the protection program, and the movement performs voltage compensation on the pressure loss side through the DC isolation bridge.

[0063] By coordinating the control unit 400 to adjust the system working state, the entire system can be shut down upon receiving an external shutdown signal, which is convenient for staff to operate.

[0064] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A DC bus voltage loss automatic switching system, characterized by: include, The voltage adjustment unit (100) is electrically connected to include: A protection filtering unit (200), a power correction unit (300), a coordination control unit (400), a safety conversion unit (500), and a stable output unit (600); The voltage adjustment unit (100) adopts a parallel redundant design.

2. The DC bus voltage loss automatic switching system according to claim 1 is characterized in that: The protection filtering unit (200) is externally connected to an input sampling circuit, the input sampling circuit is connected to a monitoring and adjusting unit (700), and the monitoring and adjusting unit (700) is in front-end and back-end interactive communication with the coordination and control unit (400).

3. A compensation control method, characterized in that: The invention comprises the DC bus voltage loss automatic switching system as claimed in claim 2, and The actual output voltage shall not be higher than the constant output voltage, forming the output condition of the movement; The output voltage must be lower than the input voltage, otherwise the system is in hot standby mode, forming the conditions for the DC blocking circuit to start; When one side of a given bus loses pressure, the movement outputs to the side that loses pressure, forming the conduction condition of the direct-isolating bridge.

4. The compensation control method according to claim 3, Its characteristics: Movement output conditions, including, The protection filter unit (200) and the stabilization output unit (600) detect voltage; When the given voltage at the module output is higher than the module output voltage, the DC isolation bridge is cut off and the movement cannot output voltage.

5. The compensation control method according to claim 3, characterized in that: The protection filter unit (200) and the stabilization output unit (600) detect voltage; When the DC bus is given on both sides and the given voltage at the module output is not higher than the module output voltage, the movement output starts.

6. The compensation control method according to claim 5, characterized in that: DC blocking circuit start-up conditions include: The output voltage of a single core is preset to be 5V lower than its input voltage; Based on the preset value, when both sides are given DC bus and the output voltage is not lower than the input voltage by 5V, the DC isolation circuit is cut off and the system is in hot standby mode; The voltage adjustment unit (100) completes voltage adjustment and the DC isolation circuit is turned on.

7. The compensation control method according to claim 5, characterized in that: The conditions for the conduction of the DC isolation bridge include: The DC-isolating bridge is arranged on the DC bus, and the DC-isolating bridge comprises at least one bidirectional conducting element and a matching trigger circuit; When one side of a given bus loses voltage, the DC-isolating bridge opens, and the movement outputs voltage to the side losing voltage through the DC-isolating bridge for voltage compensation.

8. The compensation control method according to claim 7, characterized in that: Pre-set the trigger threshold value for a given busbar voltage loss; When the DC bus voltage drops to the set value, the system starts, the DC isolation bridge opens, and the movement compensates the voltage on the voltage-losing side through the DC isolation bridge.

9. The compensation control method according to claim 3, characterized in that: The system operating state is adjusted by the coordination control unit (400), and shutdown is caused when an external shutdown signal is received.

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