A direct current overvoltage suppression device and method

Abstract

The application discloses a direct-current overvoltage suppression device and method, and belongs to the field of low-voltage direct-current power supply. The direct-current overvoltage suppression device is connected in parallel at both ends of a direct-current bus. When the change rate of the transient overvoltage of the direct-current bus is large enough, the first capacitor is turned on. Then, when the amplitude of the transient overvoltage of the direct-current bus exceeds the breakdown voltage of the stabilizing diode, the stabilizing diode is broken down, the thyristor is turned on, and the second capacitor starts to be charged. The transient transient overvoltage of the direct-current bus is injected into the second capacitor and the resistor, so that the voltage value of the direct-current bus is adjusted to be within the expected voltage threshold, the overvoltage is self-monitored and suppressed on the topology body, the overvoltage problem of the user side is actively solved, and the direct-current bus voltage is stabilized.

Description

Technical Field

[0001] This invention relates to the field of low-voltage DC power supply, and in particular to a DC overvoltage suppression device and method. Background Technology

[0002] In DC systems, bus voltage is a crucial indicator of system operation. It not only supplies power to terminal electrical appliances but also transmits the system's supply-demand balance. Voltage exceeding 107% U... n A voltage sag is a voltage deviation that lasts between 10 ms and 1 second. Voltage sags affect the normal operation of voltage-sensitive electrical equipment, causing serious economic losses and posing a serious threat to the personal safety of electricity users.

[0003] In current DC power distribution systems, an imbalance between power generation and power consumption can cause a voltage spurt on the DC bus. Therefore, adopting simple and feasible methods to absorb instantaneous power and suppress voltage spurts is essential to ensure system safety and personnel safety.

[0004] Current research on transient overvoltage suppression methods mainly focuses on passive control after a fault occurs, and primarily on the AC side, such as installing surge arresters or developing reasonable pole control and safety control strategies. However, overvoltage problems on the user side are a predictable issue during the normal operation of DC power distribution systems, and therefore, certain active suppression measures can and should be taken.

[0005] In conclusion, developing a reasonable suppression scheme for transient overvoltage problems on the user side is of great significance for ensuring the safety of the power grid and personnel at the sending end. Summary of the Invention

[0006] The purpose of this invention is to provide a DC overvoltage suppression device and method that can achieve self-monitoring and suppression of overvoltage on the topology itself, actively solve overvoltage problems on the user side, and stabilize the DC bus voltage.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] A DC overvoltage suppression device includes: a Zener diode, a thyristor, a first capacitor, a second capacitor, and a resistor;

[0009] One end of the first capacitor is connected to the positive terminal of the DC bus, and the other end of the first capacitor is connected to the cathode of the Zener diode. The anode of the Zener diode is connected to the gate of the thyristor.

[0010] The anode of the thyristor is connected to one end of the second capacitor and one end of the resistor, respectively, and the cathode of the thyristor is connected to the negative terminal of the DC bus; the other end of the second capacitor and the other end of the resistor are connected to the positive terminal of the DC bus.

[0011] Optionally, the thyristor is turned on under the following conditions: the rate of change of the DC bus voltage sag causes the first capacitor to conduct, and the amplitude of the DC bus voltage sag is greater than the reverse breakdown voltage of the Zener diode.

[0012] Optionally, after the thyristor is turned on, the second capacitor begins to charge; after the second capacitor is fully charged, the thyristor is turned off, and the electrical energy in the second capacitor is released into the resistor and consumed as heat.

[0013] A method for suppressing DC overvoltage, wherein the method applies the aforementioned DC overvoltage suppression device, and the method includes:

[0014] The DC overvoltage suppression device is connected in parallel across the two ends of the DC bus;

[0015] When an imbalance occurs between power generation and power consumption, the DC bus voltage rises and causes the first capacitor to conduct. The rise in DC bus voltage is directly applied across the Zener diode.

[0016] When the amplitude of the DC bus voltage rise exceeds the breakdown voltage of the Zener diode, the Zener diode breaks down, the thyristor turns on, and the second capacitor starts charging, thus initiating the voltage regulation process.

[0017] The voltage regulation process ends when the second capacitor is fully charged, the thyristor is turned off, and the voltage regulation process is complete.

[0018] Optionally, the condition for the thyristor to turn on is that the current flowing out of the Zener diode is greater than the thyristor's turn-on current.

[0019] Optionally, the condition for the thyristor to turn off is that the current in the second capacitor and the thyristor branch is less than the thyristor holding current.

[0020] Optionally, the process of regulating voltage continues until the second capacitor is fully charged, the thyristor is turned off, and the voltage regulation process ends, and then further includes:

[0021] The electrical energy in the second capacitor is released into the resistor and consumed as heat.

[0022] Optionally, if the spurious voltage on the DC bus cannot turn on the first capacitor after an imbalance between power generation and power consumption occurs, and the spurious voltage amplitude is less than the reverse breakdown voltage of the Zener diode, then voltage regulation control is performed through the AC / DC converter.

[0023] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0024] This invention discloses a DC overvoltage suppression device and method. The DC overvoltage suppression device is connected in parallel across the two ends of a DC bus. When the rate of change of the transient overvoltage of the DC bus is sufficiently large, the first capacitor turns on. Then, when the amplitude of the transient overvoltage of the DC bus exceeds the breakdown voltage of the Zener diode, the Zener diode breaks down, the thyristor turns on, and the second capacitor starts charging. This allows the instantaneous transient power of the DC bus to be injected into the second capacitor and the resistor, adjusting the DC bus voltage value within the expected voltage threshold. This achieves self-monitoring and suppression of overvoltage on the topology itself, actively solving the overvoltage problem on the user side and stabilizing the DC bus voltage. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a topology diagram of the DC overvoltage suppression device provided in an embodiment of the present invention;

[0027] Figure 2 A flowchart of a DC overvoltage suppression method provided in an embodiment of the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] This invention provides a DC overvoltage suppression device, which is applied at the DC bus. With low device cost, it can realize self-monitoring and suppression of overvoltage on the topology itself, actively solve the overvoltage problem on the user side, and achieve the function of stabilizing the DC bus voltage.

[0031] An embodiment of the present invention provides a DC overvoltage suppression device, such as... Figure 1 As shown, it includes: a Zener diode, a thyristor, a first capacitor, a second capacitor, and a resistor.

[0032] One end of the first capacitor is connected to the positive terminal of the DC bus, and the other end of the first capacitor is connected to the cathode of the Zener diode. The anode of the Zener diode is connected to the gate of the thyristor. The anode of the thyristor is connected to one end of the second capacitor and one end of the resistor, respectively, and the cathode of the thyristor is connected to the negative terminal of the DC bus. The other end of the second capacitor and the other end of the resistor are connected to the positive terminal of the DC bus.

[0033] As can be seen, the DC overvoltage suppression device of the present invention consists of an overvoltage absorption circuit composed of four components, including a capacitor, a diode, a thyristor, and a resistor.

[0034] Combination Figure 1 The working principle of the DC overvoltage suppression device of the present invention is as follows:

[0035] Under normal operating conditions, DC bus voltage fluctuations are negligible. Approaching 0, because When there are no large and rapid voltage fluctuations, capacitor C1 (the first capacitor) is not conducting, and C1 and Zener diode S2 share the DC bus voltage. At this time, the voltage across Zener diode S2 is much lower than its breakdown voltage u. z i g =0, thyristor turn off. If at a certain moment an imbalance between power generation and power consumption causes a sudden rise in DC bus voltage, then... The voltage is large, C1 conducts, and the spurious voltage is directly applied across the Zener diode S2. Utilizing the reverse breakdown characteristic of the Zener diode, when the spurious voltage exceeds the breakdown voltage u of the Zener diode S2... z At that time, the Zener diode S2 breaks down, i g When the current exceeds the turn-on current of thyristor S1, thyristor S1 turns on, and the spurred power flows into capacitor C. s (The second capacitor) and resistor R are used to stabilize the DC bus voltage. That is, the unique phenomenon of transient overvoltage is used to control the conduction of the switching devices, and the current control characteristics of the thyristor are used to control the absorption capacitor (capacitor C). s ) investment.

[0036] When the capacitance C s During charging, the potential at point E gradually increases, and the capacitance C... s When fully charged, the potential at point E is the same as the potential at point D, and the capacitance C... s The current in the S1 branch of the thyristor approaches 0, and this current i is less than the thyristor holding current i. h When thyristor S1 is turned off, the voltage regulation process ends. At this time, capacitor C... s Electrical energy is released into resistor R and consumed as heat.

[0037] In other words, for the thyristor to turn on during a DC bus voltage sag, two conditions must be met simultaneously: 1. The rate of change of the DC bus voltage must be sufficiently large; 2. The voltage sag amplitude must be sufficiently large, exceeding the reverse breakdown voltage of the Zener diode. Only when the rate of change of the DC bus voltage is sufficiently large can capacitor C1 conduct. Only when the voltage sag amplitude is sufficiently large can the Zener diode S2 reverse break down, allowing a large current to flow. When a slow overvoltage problem occurs (the rate of change of the DC bus voltage is relatively small, and the voltage sag amplitude is relatively small, less than the reverse breakdown voltage of the Zener diode), it can be resolved through the control mechanisms of the AC / DC converter itself.

[0038] This invention also provides a method for suppressing DC overvoltage, such as... Figure 2 As shown, this DC overvoltage suppression method uses the aforementioned DC overvoltage suppression device, and the DC overvoltage suppression method includes:

[0039] Step 1: Connect the DC overvoltage suppression device in parallel across the DC bus.

[0040] Step 2: When an imbalance occurs between power generation and power consumption, the DC bus voltage rises temporarily, causing the first capacitor to conduct. The voltage rise of the DC bus is directly applied across the Zener diode.

[0041] Step 3: When the amplitude of the DC bus voltage rise exceeds the breakdown voltage of the Zener diode, the Zener diode breaks down, the thyristor turns on, and the second capacitor starts charging, thus initiating the voltage regulation process.

[0042] The condition for a thyristor to turn on is that the current flowing out of the Zener diode is greater than the thyristor's turn-on current.

[0043] Step 4: Continue until the second capacitor is fully charged, the thyristor is turned off, and the voltage regulation process ends.

[0044] The condition for the thyristor to turn off is that the current in the second capacitor and the thyristor branch is less than the thyristor holding current.

[0045] After step 4, the electrical energy in the second capacitor is released into the resistor and consumed as heat.

[0046] If an imbalance occurs between power generation and power consumption, and the spur voltage on the DC bus cannot turn on the first capacitor, and the spur voltage amplitude is less than the reverse breakdown voltage of the Zener diode, then voltage regulation is achieved through the AC / DC converter.

[0047] This invention utilizes two objective factors—a sufficiently large rate of voltage change and a sufficiently large overvoltage value—during transient overvoltage on the DC bus to achieve self-monitoring and suppression of overvoltage at the topological level, avoiding complex detection and control circuits. By controlling the injection of current into the thyristor's control electrode to turn it on, the instantaneous power surge of the DC bus is injected into the stabilizing capacitor and resistor, adjusting the DC bus voltage value to within the expected voltage threshold, thus ensuring personnel safety, system safety, and equipment safety.

[0048] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0049] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A DC overvoltage suppression device, characterized in that, include: Zener diode, thyristor, first capacitor, second capacitor, and resistor; One end of the first capacitor is connected to the positive terminal of the DC bus, and the other end of the first capacitor is connected to the cathode of the Zener diode. The anode of the Zener diode is connected to the gate of the thyristor. The anode of the thyristor is connected to one end of the second capacitor and one end of the resistor, respectively, and the cathode of the thyristor is connected to the negative terminal of the DC bus. The other end of the second capacitor and the other end of the resistor are connected to the positive terminal of the DC bus. The thyristor and the second capacitor perform a voltage regulation process, so that the instantaneous boost power of the DC bus is injected into the second capacitor and the resistor, and the voltage value on the DC bus side is adjusted within the expected voltage threshold. The conditions for the thyristor to turn on are: the rate of change of the DC bus voltage makes the first capacitor conduct, and the amplitude of the DC bus voltage is greater than the reverse breakdown voltage of the Zener diode.

2. The DC overvoltage suppression device according to claim 1, characterized in that, After the thyristor is turned on, the second capacitor begins to charge; after the second capacitor is fully charged, the thyristor is turned off, and the electrical energy in the second capacitor is released into the resistor and consumed as heat.

3. A method for suppressing DC overvoltage, characterized in that, The DC overvoltage suppression method uses the DC overvoltage suppression device according to any one of claims 1-2, and the DC overvoltage suppression method includes: The DC overvoltage suppression device is connected in parallel across the two ends of the DC bus; When an imbalance occurs between power generation and power consumption, the DC bus voltage rises and causes the first capacitor to conduct. The rise in DC bus voltage is directly applied across the Zener diode. When the amplitude of the DC bus voltage rise exceeds the breakdown voltage of the Zener diode, the Zener diode breaks down, the thyristor turns on, and the second capacitor starts charging, thus initiating the voltage regulation process. The voltage regulation process ends when the second capacitor is fully charged, the thyristor is turned off, and the voltage regulation process is complete.

4. The DC overvoltage suppression method according to claim 3, characterized in that, The condition for the thyristor to turn on is that the current flowing out of the Zener diode is greater than the thyristor's turn-on current.

5. The DC overvoltage suppression method according to claim 3, characterized in that, The condition for the thyristor to turn off is that the current in the second capacitor and the thyristor branch is less than the thyristor holding current.

6. The DC overvoltage suppression method according to claim 3, characterized in that, The process continues until the second capacitor is fully charged, the thyristor is turned off, and the voltage regulation process ends. Afterwards, it also includes: The electrical energy in the second capacitor is released into the resistor and consumed as heat.

7. The DC overvoltage suppression method according to claim 3, characterized in that, If an imbalance occurs between power generation and power consumption, and the spur voltage on the DC bus cannot turn on the first capacitor, and the spur voltage amplitude is less than the reverse breakdown voltage of the Zener diode, then voltage regulation is achieved through the AC / DC converter.

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