Energy taking unit for thyristor switched capacitor

Abstract

The utility model discloses an energy taking unit for a thyristor switched capacitor, and belongs to the technical field of energy storage. The energy taking unit comprises a voltage type energy taking branch, a current type energy taking branch, a thyristor group, a reactive compensation loop, a power supply conditioning circuit and an energy storage member. The thyristor group and the reactive compensation loop are connected in series; the voltage type energy taking branch is connected with the thyristor group in parallel and is connected with the power supply conditioning circuit; one end of the current type energy taking branch circuit is connected between the thyristor group and the reactive compensation loop, and the other end of the current type energy taking branch circuit is connected with the power supply conditioning circuit; the power supply conditioning circuit is connected with the energy storage part; the thyristor group is connected with a power supply, and the reactive compensation loop is grounded. According to the utility model, the problem of high DC / DC cost and the reliability problem caused by DC / DC isolation voltage resistance in the prior art can be solved through a double-loop energy taking mode of the resistance-capacitance absorption circuit and the mutual inductor.

Description

Technical Field

[0001] This utility model belongs to the field of energy harvesting technology, specifically relating to an energy harvesting unit for thyristor-switched capacitors. Background Technology

[0002] Thyristor switched capacitors (TSCs) are widely used in reactive power compensation in power systems. They are used to switch different groups of capacitors by thyristors to achieve power factor compensation. In the current technology, the power supply of the triggering system of thyristor switched capacitors is mainly realized by high-voltage isolated DC / DC converters. The external power supply is converted into the power required by the triggering system through DC / DC isolation.

[0003] The problems and disadvantages of using high-voltage isolated DC / DC converters include:

[0004] (1) Since the thyristors are at different potentials, each thyristor triggering system requires a separate DC / DC power supply, which is costly.

[0005] (2) Existing technology is only applicable to low-voltage (AC 600V) and below systems. For medium and high voltage (AC 1-35KV) systems, the isolation withstand voltage of DC / DC is difficult to meet the design requirements.

[0006] It is evident that existing high-voltage isolated DC / DC technologies can no longer meet the current and future high energy requirements in this field, and how to improve high-voltage isolated DC / DC technologies has become a key point. Utility Model Content

[0007] The present invention aims to at least partially solve one of the technical problems in the aforementioned related technologies.

[0008] Therefore, the purpose of this utility model is to provide a thyristor-switched capacitor energy harvesting unit that can solve the problems of high cost of DC / DC converters and reliability issues caused by DC / DC isolation withstand voltage in the prior art by using a dual-loop energy harvesting method of RC snubber circuit and current transformer.

[0009] To solve the above-mentioned technical problems, this utility model is implemented as follows:

[0010] This utility model embodiment provides an energy harvesting unit for thyristor-switched capacitors. The energy harvesting unit includes: a voltage-type energy harvesting branch, a current-type energy harvesting branch, a thyristor group, a reactive power compensation circuit, a power conditioning circuit, and an energy storage device.

[0011] The thyristor group and the reactive power compensation circuit are connected in series;

[0012] The voltage-type energy harvesting branch is connected in parallel with the thyristor group and is also connected to the power conditioning circuit.

[0013] One end of the current-type energy harvesting branch is connected between the thyristor group and the reactive power compensation circuit, and the other end is connected to the power conditioning circuit.

[0014] The power conditioning circuit is connected to the energy storage device;

[0015] The thyristor group is connected to the power supply, and the reactive power compensation circuit is grounded.

[0016] In addition, the thyristor-switched capacitor energy harvesting unit according to this utility model may also have the following additional technical features:

[0017] In some embodiments, the voltage-type energy harvesting branch includes a resistor-capacitor (RC) snubber circuit and an RC energy harvesting circuit; the RC snubber circuit and the RC energy harvesting circuit are connected in series, and the RC energy harvesting circuit is connected to the power conditioning circuit.

[0018] In some embodiments, the RC snubber circuit includes a first resistor R1 and a first capacitor C1; the first resistor R1 and the first capacitor C1 are connected in series to form a composite circuit for overvoltage suppression and energy extraction.

[0019] In some embodiments, the current-source energy harvesting branch includes an interconnected transformer energy harvesting circuit and a current transformer; the current transformer is connected in series between the thyristor group and the reactive power compensation circuit; the transformer energy harvesting circuit is connected to the power conditioning circuit.

[0020] In some embodiments, the primary side of the current transformer is connected in series with the input terminal of the reactive power compensation circuit, and the secondary side is connected to the transformer energy harvesting circuit, for collecting current-type energy when the thyristor group is turned on.

[0021] In some embodiments, the thyristor group includes a first thyristor T1 and a second thyristor T2; the first thyristor T1 and the second thyristor T2 are connected in parallel, and the anode and cathode of the first thyristor T1 and the second thyristor T2 are arranged in opposite directions to form an anti-parallel structure;

[0022] The gates of the first thyristor T1 and the second thyristor T2 are connected to an external trigger circuit to receive trigger signals.

[0023] In some embodiments, the reactive power compensation circuit includes a first inductor L1 and a second capacitor C2; the first inductor L1 and the second capacitor C2 are connected in series to form an LC series resonant circuit.

[0024] In some of these embodiments, the energy storage device is an energy storage capacitor C3.

[0025] In some embodiments, the energy storage capacitor C3 is connected to an external trigger circuit to supply power to the trigger circuit.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] In this embodiment of the utility model, the thyristor-switched capacitor energy harvesting unit uses the thyristor-switched capacitor's own RC snubber circuit and current transformer to harvest energy. Compared with the existing external power supply and DC / DC conversion method, the energy harvesting circuit of this utility model does not require electrical isolation, which has a lower cost advantage. At the same time, because no electrical isolation is required, the energy harvesting power supply has higher safety and reliability.

[0028] In this embodiment of the invention, the thyristor-triggered capacitor energy harvesting unit provided has an energy harvesting method applicable to low, medium, and high voltage thyristor-triggered capacitor applications, thus having a wider range of applications.

[0029] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the energy harvesting unit for thyristor-switched capacitors disclosed in one embodiment of the present invention. Detailed Implementation

[0031] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0032] The embodiments of this utility model will be described in detail below with reference to the accompanying drawings, through specific examples and application scenarios.

[0033] Please see Figure 1As shown in some embodiments of this utility model, an energy harvesting unit for thyristor-switched capacitors is provided, including an RC snubber circuit, a thyristor group, a current transformer, a reactive power compensation circuit, an RC energy harvesting circuit, a current transformer energy harvesting circuit, a power conditioning circuit, and an energy storage device. The RC snubber circuit and the RC energy harvesting circuit are connected in series, and their series branch is connected in parallel with the thyristor group. One end of this parallel circuit is connected to a power supply, and the other end is connected in series with the current transformer (CT) and the reactive power compensation circuit inductor before being grounded. The power conditioning circuit is connected to both the RC energy harvesting circuit and the current transformer energy harvesting circuit, and the current transformer energy harvesting circuit is then connected to the current transformer (CT). The energy storage device is connected to the power conditioning circuit.

[0034] In the above embodiments, the energy storage device can be an energy storage capacitor C3.

[0035] In some embodiments of this utility model, the RC snubber circuit includes a first resistor R1 and a first capacitor C1, which are connected in series to form a composite circuit for overvoltage suppression and energy extraction. The first resistor R1, also called a damping resistor, limits the charging and discharging current of the first capacitor C1, suppresses LC oscillation, and prevents overvoltage when the thyristor is turned off. Simultaneously, it serves as a current-limiting element in the RC energy extraction circuit, forming a voltage divider unit with the first capacitor C1 when the thyristor is turned off. The first capacitor C1, also called a snubber capacitor, absorbs the overvoltage energy when the thyristor is turned off, suppresses the voltage rise rate du / dt, and protects the thyristor. When the thyristor is turned off, it acts as an energy storage element in the RC energy extraction circuit, providing energy to subsequent circuits through voltage division.

[0036] In some embodiments of this invention, the thyristor group includes a first thyristor T1 and a second thyristor T2, which are connected in parallel. The cathodes and anodes of the first thyristor T1 and the second thyristor T2 are arranged in opposite directions, forming an anti-parallel structure. The gates of the two thyristors are connected to a trigger circuit (not shown in the figure) to receive trigger signals. The rated voltage of the thyristors must match the system voltage level, and the rated current must meet the inrush current requirements when the capacitor is switched on or off. The thyristor group acts as a control switch for circuit on / off. Under the action of the trigger signal, it conducts, connecting the second capacitor C2 to or disconnecting it from the power grid to achieve reactive power compensation. Simultaneously, it serves as a switching element for the operating state of the energy harvesting unit; its on / off state determines the switching of the energy harvesting circuit.

[0037] In some embodiments of this utility model, the reactive power compensation circuit includes a first inductor L1 and a second capacitor C2, which are connected in series to form an LC series resonant circuit. The first inductor L1 can suppress the inrush current at the moment of capacitor switching, avoiding excessive di / dt on the thyristor; at the same time, when the thyristor is turned on, it forms a current path with the second capacitor C2, providing a carrier for the induced current of the current transformer (CT). The second capacitor C2 can provide capacitive reactive power to compensate for the inductive reactive power of the system and improve the power factor; the second capacitor C2 serves as the energy carrier of the energy harvesting unit, and its terminal voltage change drives the RC energy harvesting circuit to work, while its charging and discharging current drives the transformer energy harvesting circuit to work.

[0038] In some embodiments of this utility model, the primary side of the current transformer (CT) is connected in series with the input terminal of the first inductor L1 in the reactive power compensation circuit, and the secondary side is connected to the transformer's energy extraction circuit. The transformation ratio is designed according to the system's rated current and energy extraction power requirements (e.g., 100A on the primary side / 5A on the secondary side). The function of the current transformer (CT) is to sense the load current flowing through the first inductor L1 when the thyristor is turned on, converting the large current into a small current on the secondary side to provide energy input for the transformer's energy extraction circuit. It adopts a through-hole or wound structure to ensure electrical isolation from the main circuit (but the energy extraction circuit does not require high-voltage isolation, unlike traditional DC / DC schemes).

[0039] In the above embodiment, the energy harvesting circuit includes an RC energy harvesting circuit and a current transformer energy harvesting circuit. The RC energy harvesting circuit is directly connected in series with one end of the RC snubber circuit to harvest voltage-type energy. The current transformer energy harvesting circuit is connected to the secondary side of the current transformer (CT) to harvest current-type energy. The energy harvested by both circuits is conditioned by the power conditioning circuit to supply power to the energy storage capacitor C3.

[0040] In the above embodiments, the working principle of the energy harvesting unit of this utility model is as follows: When the first thyristor T1 and the second thyristor T2 are not conducting, the current of the first resistor R1 and the first capacitor C1 flows through the RC energy harvesting circuit, and after being conditioned by the power conditioning circuit, it supplies power to the energy storage capacitor C3. The energy storage capacitor C3 is used to provide a stable power supply for the trigger circuit. When the first thyristor T1 and the second thyristor T2 are conducting, the voltage across the first resistor R1 and the first capacitor C1 is zero, and no current flows. At this time, current flows through the first inductor L1 and the second capacitor C2, and the current transformer CT induces a current on its secondary side. This current is transformed by the transformer energy harvesting circuit and then sent to the power conditioning circuit to supply power to the energy storage capacitor C3.

[0041] Any part of this utility model that is not described in detail can be referred to the prior art or the art known to those skilled in the art. This embodiment does not limit it and will not describe it in detail here.

[0042] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. A power deriving unit for a thyristor switched capacitor, characterized by, The energy harvesting unit includes: a voltage-type energy harvesting branch, a current-type energy harvesting branch, a thyristor group, a reactive power compensation circuit, a power conditioning circuit, and an energy storage device. The thyristor group and the reactive power compensation circuit are connected in series; The voltage-type energy harvesting branch is connected in parallel with the thyristor group and is also connected to the power conditioning circuit. One end of the current-type energy harvesting branch is connected between the thyristor group and the reactive power compensation circuit, and the other end is connected to the power conditioning circuit. The power conditioning circuit is connected to the energy storage device; The thyristor group is connected to the power supply, and the reactive power compensation circuit is grounded.

2. The thyristor switched capacitor power deriving unit of claim 1, wherein, The voltage-type energy harvesting branch includes a resistor-capacitor (RC) absorption circuit and an RC energy harvesting circuit; the RC absorption circuit and the RC energy harvesting circuit are connected in series, and the RC energy harvesting circuit is connected to the power conditioning circuit.

3. The thyristor switched capacitor power deriving unit of claim 2, wherein, The RC absorption circuit includes a first resistor R1 and a first capacitor C1; the first resistor R1 and the first capacitor C1 are connected in series to form a composite circuit for overvoltage suppression and energy extraction.

4. The thyristor switched capacitor power deriving unit of claim 1, wherein, The current-source energy harvesting branch includes an interconnected transformer energy harvesting circuit and a current transformer; the current transformer is connected in series between the thyristor group and the reactive power compensation circuit; the transformer energy harvesting circuit is connected to the power conditioning circuit.

5. The thyristor switched capacitor power deriving unit of claim 4, wherein, The primary side of the current transformer is connected in series with the input terminal of the reactive power compensation circuit, and the secondary side is connected to the transformer energy harvesting circuit, which is used to collect current-type energy when the thyristor group is turned on.

6. The thyristor switched capacitor power deriving unit of claim 1, wherein, The thyristor group includes a first thyristor T1 and a second thyristor T2; the first thyristor T1 and the second thyristor T2 are connected in parallel, and the anode and cathode of the first thyristor T1 and the second thyristor T2 are arranged in opposite directions to form an anti-parallel structure. The gates of the first thyristor T1 and the second thyristor T2 are connected to an external trigger circuit to receive trigger signals.

7. The thyristor switched capacitor power deriving unit of claim 1, wherein, The reactive power compensation circuit includes a first inductor L1 and a second capacitor C2; the first inductor L1 and the second capacitor C2 are connected in series to form an LC series resonant circuit.

8. The thyristor switched capacitor power deriving unit of claim 1, wherein, The energy storage device is an energy storage capacitor C3.

9. The thyristor switched capacitor power deriving unit of claim 8, wherein, The energy storage capacitor C3 is connected to an external trigger circuit to supply power to the trigger circuit.

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