Active voltage sag treatment device

Abstract

The utility model aims to provide the active voltage sag treatment device which is high in stability, improves the utilization rate of electric energy, can replace an alternating current contactor, controls the closing and opening of the circuit breaker through the electric operating mechanism, ensures the reliability and stability of the whole set of voltage sag treatment device, and reduces the power consumption of a secondary power supply at the same time. The device comprises an alternating current inlet wire switch, an alternating current outlet wire switch, an alternating current bypass switch, an alternating current bypass contactor, a quick switch, a three-phase isolation transformer, an alternating current circuit breaker, a power unit, a direct current circuit breaker and an energy storage battery unit. The utility model is applied to the technical field of voltage sag.

Description

Technical Field

[0001] This utility model relates to the technical field of voltage sag, and in particular to an active voltage sag mitigation device. Background Technology

[0002] The most common power quality problems in power grids are voltage drops, voltage spikes, overvoltages, undervoltages, and voltage imbalances. These power quality events can cause load tripping, equipment failures, and industrial process interruptions. In minor cases, they can lead to product quality accidents, resulting in economic losses of hundreds of thousands, millions, or even tens of millions of dollars. In severe cases, they can even cause major safety accidents, causing huge economic losses and adverse social impacts on enterprises and society.

[0003] With the development of IT, automation, and power electronics technologies, users have increasingly higher requirements for power supply quality, making power quality a primary concern in the international power supply industry. According to authoritative data from EPRI (Electrical and Power Research Institute), over 92% of power quality events are voltage sags, while other power quality events account for less than 8%.

[0004] As can be seen from the above, effectively solving the voltage sag problem is a key factor in achieving high-quality power supply. The mainstream methods for managing voltage sags are through devices such as UPS (Uninterruptible Power Supply), DC-BANK (DC Voltage Support), DVR (Dynamic Voltage Regulator), and AVC (Automatic Voltage Regulator).

[0005] UPS: The technology is mature and mainly addresses voltage continuity and power quality issues. It can also solve voltage sag issues relatively well. However, this device is not specifically designed for voltage sag problems. It has high device costs, complex systems, low efficiency, uses batteries for energy storage components, and requires a large amount of maintenance. Therefore, it is not suitable for professionally handling voltage sag problems.

[0006] DC-BANK: The technology is mature, but it only compensates for voltage sags for sensitive loads with DC support. It has a narrow range of applications and cannot effectively deal with voltage sags, so it can only be used in a few fields.

[0007] DVR and AVC: Emerging technologies specifically designed to address voltage sag issues. They are widely applicable to various loads and are effective devices for solving voltage sag problems. However, whether applied in series or parallel, these devices have complex topologies, low energy storage component utilization, large size, poor environmental adaptability, and varying limitations on the depth of voltage sag compensation. They require specialized personnel to design solutions for implementation and are highly specialized.

[0008] Voltage sags or dips refer to the phenomenon where the effective value of the supply voltage suddenly drops and then recovers within a short period of time. In power grids, this phenomenon typically lasts between 0.5 and 1.5 seconds. The Institute of Electrical and Electronics Engineers (IEEE) defines a voltage sag as a rapid drop in the effective value of the supply voltage to 90%-10% of its rated value, followed by a recovery to near the normal value. Prolonged voltage sags can lead to abnormal equipment shutdowns. With the rapid development of my country's economic construction and power industry, the large-scale application of high-voltage direct current transmission, new energy power generation, and variable frequency speed control motors has made the dynamic reactive power demand and transient voltage instability problems of large power grids more prominent. Among these, voltage sags account for the highest proportion and cause the greatest economic losses, becoming the most serious power quality problem. Therefore, accurately identifying voltage sags is crucial for maintaining the safe and stable operation of the power grid and is essential for their prevention and management. Traditional voltage sag detection typically involves first reducing the voltage using a transformer, then rectifying and dividing the voltage, and finally using a microcontroller to collect the voltage signal and obtain the voltage detection data. This method requires transformers and other components, resulting in complex circuit structures and high costs.

[0009] For example, Chinese patent CN221828610U discloses an active voltage sag control device. The voltage detection circuit mainly consists of discrete resistors and operational amplifiers. Compared to traditional voltage detection circuits, it has the advantages of simple circuit structure, low cost, and reduced installation space required in practical applications. Therefore, it is necessary to provide an active voltage sag control device that offers high stability, improves energy utilization, can replace AC contactors, and controls the closing and opening of circuit breakers through an electric operating mechanism, ensuring the reliability and stability of the entire voltage sag control device while reducing the power consumption of the secondary power supply. Utility Model Content

[0010] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide an active voltage sag control device with high stability and improved power utilization. It can replace AC contactors and control the closing and opening of circuit breakers through an electric operating mechanism, ensuring the reliability and stability of the entire voltage sag control device, while reducing the power consumption of the secondary power supply.

[0011] The technical solution adopted by this utility model is as follows: This utility model includes an AC incoming line switch, an AC outgoing line switch, an AC bypass switch, an AC bypass contactor, a fast-switching switch, a three-phase isolation transformer, an AC circuit breaker, a power unit, a DC circuit breaker, and an energy storage battery unit; the input terminal of the AC incoming line switch is connected to the power grid, the input terminal of the fast-switching switch is connected to the output terminal of the AC incoming line switch, the input terminal of the AC outgoing line switch is connected to the output terminal of the fast-switching switch, the bypass contactor is connected in parallel with the fast-switching switch, the input terminal of the AC bypass switch is connected to the input terminal of the AC incoming line switch, the output terminal of the AC bypass switch is connected to the output terminal of the AC outgoing line switch, the input terminal of the AC circuit breaker is connected to the output terminal of the fast-switching switch, the output terminal of the AC circuit breaker is connected to the primary input terminal of the three-phase isolation transformer, the DC output terminal of the power unit is connected to the input terminal of the DC circuit breaker, and the input terminal of the energy storage battery unit is connected to the output terminal of the DC circuit breaker.

[0012] As described above, this application is based on electric operating mechanism control, which can functionally replace the AC contactor connected to the AC output side of the inverter in the device. The inverter in the device controls the closing and opening of the circuit breaker through the electric operating mechanism, thereby ensuring the reliability and stability of the entire voltage sag mitigation device, while reducing the power consumption of the secondary power supply.

[0013] In a preferred embodiment, the active voltage sag mitigation device further includes a filter capacitor, a small reactor, and a large reactor. The input terminal of the small reactor is connected to the output terminal of the three-phase isolation transformer, the input terminal of the large reactor is connected to the output terminal of the small reactor, the AC input terminal of the power unit is connected to the output terminal of the large reactor, one end of the filter capacitor is connected in parallel between the output terminal of the small reactor and the input terminal of the large reactor, and the other end of the filter capacitor is connected to the neutral (N) line of the power grid.

[0014] In a preferred embodiment, the AC incoming switch, the AC outgoing switch, and the AC bypass switch are all AC disconnect switches.

[0015] In a preferred embodiment, the fast-switch is an electronic switch with a thyristor as the switching device, and the thyristor is controlled to turn on or off by an external host computer. Both the input and output terminals of the fast-switch are pluggable conductive clips.

[0016] A preferred embodiment is that the AC circuit breaker is controlled by an electric operating mechanism and operates stably under the rated control power supply voltage %Ue.

[0017] In a preferred embodiment, the active voltage sag mitigation device further includes an energy storage inverter, which includes the AC circuit breaker, the three-phase isolation transformer, the small reactor, the large reactor, the filter capacitor, the power unit, and the DC circuit breaker, with the three-phase isolation transformer located at the output terminal of the energy storage inverter.

[0018] In a preferred embodiment, the DC circuit breaker acts as a disconnecting device, rapidly disconnecting the energy storage battery unit when a fault occurs.

[0019] A preferred embodiment is that the energy storage battery unit uses a carbon-based capacitor as the energy storage medium. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the principle of this utility model.

[0021] Figure 2 This is a front view structural diagram of this utility model.

[0022] Figure 3 This is an internal structural diagram of the present invention. Detailed Implementation

[0023] like Figures 1 to 3 As shown, in this embodiment, the present invention includes an AC incoming line switch 1QS1, an AC outgoing line switch 1QS2, an AC bypass switch 1QS3, an AC bypass contactor 1KM, a fast-switching switch FS, a three-phase isolation transformer TR, an AC circuit breaker K1, a power unit IGBT, a DC circuit breaker 2QF1, and an energy storage battery unit CB. The input terminal of the AC incoming line switch 1QS1 is connected to the power grid, the input terminal of the fast-switching switch FS is connected to the output terminal of the AC incoming line switch 1QS1, the input terminal of the AC outgoing line switch 1QS2 is connected to the output terminal of the fast-switching switch FS, and the bypass contactor 1KM is connected to the fast-switching switch FS. The fast-switching switches FS are connected in parallel. The input terminal of the AC bypass switch 1QS3 is connected to the input terminal of the AC incoming switch 1QS1. The output terminal of the AC bypass switch 1QS3 is connected to the output terminal of the AC outgoing switch 1QS2. The input terminal of the AC circuit breaker K1 is connected to the output terminal of the fast-switching switch FS. The output terminal of the AC circuit breaker K1 is connected to the primary input terminal of the three-phase isolation transformer TR. The DC output terminal of the power unit IGBT is connected to the input terminal of the DC circuit breaker 2QF1. The input terminal of the energy storage battery unit CB is connected to the output terminal of the DC circuit breaker 2QF1.

[0024] like Figure 1As shown, in this embodiment, the active voltage sag control device further includes a filter capacitor C, a small reactor L2, and a large reactor L1. The input terminal of the small reactor L2 is connected to the output terminal of the three-phase isolation transformer TR, the input terminal of the large reactor L1 is connected to the output terminal of the small reactor L2, the AC input terminal of the power unit IGBT is connected to the output terminal of the large reactor L1, one end of the filter capacitor C is connected in parallel between the output terminal of the small reactor L2 and the input terminal of the large reactor L1, and the other end of the filter capacitor C is connected to the N line of the power grid.

[0025] The small reactor L2, the large reactor L1, and the filter capacitor C are important components of the inverter system. Through the LCL filter circuit composed of their reactance and capacitor, harmonic signals in the power grid are filtered out, making the power output of the inverter purer and more stable, and reducing interference to other electrical equipment.

[0026] like Figure 1 As shown, in this embodiment, the AC incoming switch 1QS1, the AC outgoing switch 1QS2, and the AC bypass switch 1QS3 are all AC disconnect switches. Taking a 300KVA active voltage sag mitigation device as an example, the AC disconnect switch does not have a dedicated arc-extinguishing device and cannot interrupt load current and short-circuit current.

[0027] like Figure 1 As shown, in this embodiment, the fast-switching switch FS is an electronic switch with a thyristor as the switching device. The thyristor is turned on or off by an external host computer. Both the input and output terminals of the fast-switching switch FS use pluggable conductive clips.

[0028] like Figure 1 As shown, in this embodiment, the AC circuit breaker K1 is controlled by an electric operating mechanism, which operates stably under a rated control power supply voltage of 85-110%Ue. The electric operating mechanism adopts advanced switching power supply technology and is driven by a small permanent magnet motor. It can be used for both AC and DC power and has a low operating current. Taking a high-power 300KVA active voltage sag device as an example, according to calculations, the AC circuit breaker K1 needs to be 630A, and the matching electric operating mechanism is also 630A. The motor power required for closing or opening the operating mechanism is 35W, which is significantly less than the pull-in power consumption of the AC contactor coil under the same current. At the same time, the electric operating mechanism can only operate when it receives the closing or opening command; it will not operate without receiving the closing or opening command, thus ensuring high reliability.

[0029] like Figure 1As shown, in this embodiment, the active voltage sag mitigation device further includes an energy storage inverter. The energy storage inverter includes the AC circuit breaker K1, the three-phase isolation transformer TR, the small reactor L2, the large reactor L1, the filter capacitor C, the power unit IGBT, and the DC circuit breaker 2QF1. The three-phase isolation transformer TR is located at the output terminal of the energy storage inverter, thereby improving the device's resistance to grid overvoltage, grid and load-side overcurrent, interference, and single-point grounding within the device.

[0030] like Figure 1 As shown, in this embodiment, the DC circuit breaker 2QF1 acts as a disconnecting device. When the energy storage battery unit CB fails, the DC circuit breaker 2QF1 quickly disconnects the energy storage battery unit CB to prevent the fault from spreading to other parts and ensure the safety of the entire system.

[0031] like Figure 1 As shown, in this embodiment, the energy storage battery unit CB uses a carbon-based capacitor as the energy storage medium, which has fast dynamic response speed and high power characteristics, good consistency, no need for balancing between individual cells, cycle life of more than 10,000 cycles and maintenance-free operation in an ambient temperature range of -20 to +55℃.

[0032] like Figure 1 As shown, in this embodiment, the bypass contactor 1KM is powered by a coil voltage of DC48V. Under normal operation of the entire sag device or during the process of returning to the grid, if the fast-switching switch FS fails (accidentally trips or cannot be closed), the load is powered by the inverter during the fault of the fast-switching switch FS, and the bypass contactor 1KM is closed at the same time, and the equipment operates in bypass mode.

[0033] like Figure 1 As shown, in this embodiment, the power unit IGBT uses an IGBT module for voltage conversion. IGBTs have many advantages, including high input impedance, low control power, simple drive circuit, fast switching speed, large on-state current, low on-state voltage drop, and low loss. They are currently the most mainstream devices in the power semiconductor market.

[0034] In this embodiment, this application is widely used in the semiconductor industry, optoelectronic manufacturing, steel industry, vehicle equipment manufacturing, petrochemical and other fields to provide backup short-time energy storage solutions, effectively addressing issues such as voltage dips, voltage swells, and short-term interruptions, and features strong stability, high reliability, and high efficiency.

[0035] Although the embodiments of this utility model are described with reference to actual solutions, they do not constitute a limitation on the meaning of this utility model. For those skilled in the art, modifications to the implementation schemes and combinations with other schemes based on this specification are obvious.

Claims

1. An active voltage sag control device, characterized in that: It includes an AC incoming switch (1QS1), an AC outgoing switch (1QS2), an AC bypass switch (1QS3), an AC bypass contactor (1KM), a fast-switching switch (FS), a three-phase isolation transformer (TR), an AC circuit breaker (K1), a power unit (IGBT), a DC circuit breaker (2QF1), and an energy storage battery unit (CB). The input terminal of the AC incoming switch (1QS1) is connected to the power grid, the input terminal of the fast-switching switch (FS) is connected to the output terminal of the AC incoming switch (1QS1), the input terminal of the AC outgoing switch (1QS2) is connected to the output terminal of the fast-switching switch (FS), and the bypass contactor (1KM) is connected to the fast-switching switch (1QS2). The AC bypass switch (1QS3) is connected in parallel with the input terminal of the AC incoming switch (1QS1). The output terminal of the AC bypass switch (1QS3) is connected to the output terminal of the AC outgoing switch (1QS2). The input terminal of the AC circuit breaker (K1) is connected to the output terminal of the fast-switching switch (FS). The output terminal of the AC circuit breaker (K1) is connected to the primary input terminal of the three-phase isolation transformer (TR). The DC output terminal of the power unit (IGBT) is connected to the input terminal of the DC circuit breaker (2QF1). The input terminal of the energy storage battery unit (CB) is connected to the output terminal of the DC circuit breaker (2QF1).

2. The active voltage sag control device according to claim 1, characterized in that: The active voltage sag control device further includes a filter capacitor (C), a small reactor (L2), and a large reactor (L1). The input terminal of the small reactor (L2) is connected to the output terminal of the three-phase isolation transformer (TR). The input terminal of the large reactor (L1) is connected to the output terminal of the small reactor (L2). The AC input terminal of the power unit (IGBT) is connected to the output terminal of the large reactor (L1). One end of the filter capacitor (C) is connected in parallel between the output terminal of the small reactor (L2) and the input terminal of the large reactor (L1). The other end of the filter capacitor (C) is connected to the neutral (N) line of the power grid.

3. The active voltage sag control device according to claim 1, characterized in that: The AC incoming switch (1QS1), the AC outgoing switch (1QS2), and the AC bypass switch (1QS3) are all AC disconnect switches.

4. The active voltage sag control device according to claim 1, characterized in that: The fast-switching switch (FS) is an electronic switch with a thyristor as the switching device. The thyristor is turned on or off by an external host computer. Both the input and output terminals of the fast-switching switch (FS) use pluggable conductive clips.

5. The active voltage sag control device according to claim 1, characterized in that: The AC circuit breaker (K1) is controlled by an electric operating mechanism and operates stably under the rated control power supply voltage (85-110)%Ue.

6. The active voltage sag control device according to claim 2, characterized in that: The active voltage sag mitigation device also includes an energy storage inverter, which includes the AC circuit breaker (K1), the three-phase isolation transformer (TR), the small reactor (L2), the large reactor (L1), the filter capacitor (C), the power unit (IGBT), and the DC circuit breaker (2QF1). The three-phase isolation transformer (TR) is located at the output terminal of the energy storage inverter.

7. The active voltage sag control device according to claim 1, characterized in that: The DC circuit breaker (2QF1) serves as a disconnecting device. When the energy storage battery unit (CB) fails, the DC circuit breaker (2QF1) quickly disconnects the energy storage battery unit (CB).

8. The active voltage sag control device according to claim 1, characterized in that: The energy storage battery unit (CB) uses a carbon-based capacitor as the energy storage medium.

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