Fast response magnetic controlled reactor based on active field regulation and method

Abstract

The application discloses a quick-response magnetic control reactor and method based on active excitation regulation, which comprises a core with a plurality of winding columns, working coils, auxiliary coils and excitation coils being wound on the winding columns, the working coils being connected in parallel to a working alternating current circuit, the auxiliary coils and the excitation coils being connected with an excitation circuit, the excitation circuit comprising a rectifier bridge with an input end connected with the auxiliary coils, an output end of the rectifier bridge being connected with an input end of a full-bridge, an output end of the full-bridge being connected with the excitation coils, and a storage capacitor being connected in parallel between the rectifier bridge and the full-bridge. The application is used to solve the problem of the response speed being inhibited by the induced electromotive force generated by the working coils of the magnetic valve self-excitation type.

Description

Technical Field

[0001] This invention relates to a fast-response magnetically controlled reactor and method based on active excitation regulation. Background Technology

[0002] The existing structure of a magnetically controlled reactor consists of a working coil and an excitation coil wound around an iron core column. By controlling the magnetomotive force generated by the excitation coil, the magnetic saturation level of the iron core is changed, thereby altering the equivalent inductance value of the working coil and adjusting the inductance and capacity of the magnetically controlled reactor, making it controllable. Common structures include the solenoid valve self-excited type and the split-core separately excited type. The solenoid valve self-excited type has taps drawn from each of the upper and lower half-coils and connected to a thyristor. This generates a DC excitation current through autotransformation, which in turn changes the saturation level of the iron core to adjust the reactor's operating state. By controlling the conduction angle of the thyristor, the magnitude of the DC excitation current can be changed, thus smoothly adjusting its output capacity and inductance value. The split-core separately excited type has an additional excitation coil wound around the working iron core column, powered by an external DC power supply. Changing the current output of the external DC power supply changes the current in the excitation coil, thereby changing the iron core's operating state. The response speed of a magnetically controlled reactor is a crucial parameter, referring to the time required for the reactor to transition from no-load to rated load or vice versa. It is primarily related to the rate of change of the DC component, the magnitude of the DC current, and the magnitude of the control voltage. Theoretically, we want the magnetically controlled reactor to be able to excite and demagnetize rapidly, and to smoothly and quickly change its inductance and capacity as needed during stable operation. This requires a more optimized excitation system. In special applications such as wind farms, dynamic reactive power step size, electrified railway traction, and voltage flicker suppression, the response speed requirements for magnetically controlled reactors are very high, requiring them to reach rated output within several power frequency cycles. Without any improvements to the response speed, the response time is at least 0.2 seconds, which is insufficient to meet the requirements for rapid response.

[0003] Typical excitation methods for magnetically controlled reactors are self-excited (sole valve) and split-core separately excited (split-core) types. Self-excited reactors have a slower response speed because the excitation is generated by the reactor's autocoupling. The working coil and excitation coil share a common section of the coil, so the current flowing through the excitation coil is affected by the equivalent inductance of the working coil. The induced electromotive force (EMF) generated in the working coil by the AC component of the working current impedes the change in the excitation coil, suppressing its response speed. In split-core separately excited reactors, the working coil and excitation coil are separate coils connected to the system and excitation circuit respectively, linked only by a magnetic field. Therefore, the EMF induced in the working coil does not impede the change in the excitation coil. However, the separately applied external DC excitation power supply increases the cost of the magnetically controlled reactor system and does not save energy. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a fast-response magnetically controlled reactor and method based on active excitation regulation, which is used to solve the problem that the induced electromotive force generated by the working coil in the self-excited magnetic valve suppresses the change of excitation current and suppresses the response speed.

[0005] To address the above problems, the present invention provides

[0006] A fast-response magnetically controlled reactor based on active excitation regulation includes an iron core with multiple winding columns. A working coil, an auxiliary coil, and an excitation coil are wound on the winding columns. The working coil is connected in parallel to a working AC circuit. The auxiliary coil and the excitation coil are connected to an excitation circuit. The excitation circuit includes a rectifier bridge whose input terminal is connected to the auxiliary coil. The output terminal of the rectifier bridge is connected to the input terminal of a fully controlled bridge. The output terminal of the fully controlled bridge is connected to the excitation coil. An energy storage capacitor is connected in parallel between the rectifier bridge and the fully controlled bridge.

[0007] The iron core has four winding posts. The excitation coil is a single coil, while the working coil and the auxiliary coil are both double coils with opposite winding directions. The excitation coil is wound around one end of the two middle winding posts, the double coils in the working coil are wound around the other end of the two middle winding posts, and the double coils in the auxiliary coil are wound around the first and last winding posts.

[0008] The fully controlled bridge is an IGBT fully controlled bridge, and also includes a controller, which controls the IGBT fully controlled bridge through the IGBT drive circuit.

[0009] By controlling the IGBT fully controlled bridge, the magnitude of the DC excitation current can be adjusted to regulate the inductance and capacity of the magnetically controlled reactor.

[0010] The controller adjusts the IGBT duty cycle and PWM pulse width to control the instantaneous current output by the rectifier bridge. i As a feedback quantity, it corresponds to the command current issued by the controller. i ref The difference is calculated, and after being processed by PI closed-loop regulation, the difference is output as a PWM control signal, which is sent to the IGBT drive circuit to control the IGBT fully controlled bridge.

[0011] The beneficial effects of this invention are as follows:

[0012] 1. An auxiliary excitation coil is wound on the winding column to power the excitation system through the induced voltage, thus saving energy; two auxiliary excitation coils are set to increase the induced electromotive force; the excitation coil and the working coil are separated to avoid affecting the excitation current response speed.

[0013] 2. The excitation system combines a rectifier bridge, capacitors, and a fully controlled bridge to generate a controllable DC excitation source. Since the response speed is related to the rise rate of the DC current in the excitation circuit, and the excitation coil is equivalent to an inductor in the circuit, preventing sudden current changes and suppressing excitation current variations, this significantly slows down the establishment of the excitation current in the excitation circuit. Using a capacitor as an intermediary to power the excitation coil, forming an LC series circuit, alleviates the current-limiting effect of the inductor to some extent, thus accelerating the response speed.

[0014] If the equivalent inductance of the excitation coil is known, an LC oscillation circuit can be further constructed by accurately calculating and selecting a suitable capacitor value, so that the response speed can be maximized.

[0015] 3. When the inductance and capacity of the reactor need to be changed, by... i ref and actual excitation current i The comparison enables PI closed-loop control, allowing the inductance value to change rapidly.

[0016] 4. The winding method of this invention enables the reactor to draw power from itself, which saves costs, reduces the use of DC power supply, and avoids the problem of the induced electromotive force generated by the working coil in the solenoid valve self-excited type suppressing the change of excitation current and suppressing the response speed.

[0017] 5. The excitation circuit is constructed using a fully controlled IGBT circuit. When demagnetizing, the thyristor can be actively adjusted to reverse the charging of the capacitor by the excitation coil, thus making the demagnetization speed faster. Attached Figure Description

[0018] The invention will be further described below with reference to the accompanying drawings:

[0019] Figure 1 This is a schematic diagram of the structure of the present invention.

[0020] Figure 2 This is the circuit diagram of the present invention.

[0021] In the diagram: 1. Iron core; 2. Working coil; 3. Working AC circuit; 4. Auxiliary coil; 5. Excitation coil; 6. Excitation circuit; 6. Fully controlled bridge; 61. Capacitor; 62. Rectifier bridge; 63. IGBT drive circuit; 64. Controller; 65. Detailed Implementation

[0022] like Figure 1As shown, a fast-response magnetically controlled reactor based on active excitation regulation includes an iron core 1, an excitation coil 5, a working coil 2, and an auxiliary coil 4. The iron core 1 has four winding posts, designated as posts A, B, C, and D. Both the working coil 2 and the auxiliary coil 4 are double coils wound in opposite directions. The excitation coil 5 is wound around one end of posts B and C, while the double coils in the working coil 2 are wound around the other ends of posts B and C. The double coils in the auxiliary coil 4 are wound around posts A and D. Coil 2 is connected in parallel to the working AC circuit 3. Auxiliary coil 4 and excitation coil 5 are connected to excitation circuit 6. Excitation circuit 6 includes a rectifier bridge 63 whose input terminal is connected to auxiliary coil 4. The output terminal of rectifier bridge 63 is connected to the input terminal of IGBT fully controlled bridge 61. The output terminal of IGBT fully controlled bridge 61 is connected to excitation coil 5. Energy storage capacitor 62 is connected in parallel between rectifier bridge 63 and IGBT fully controlled bridge 61. It also includes a controller 65. The controller 65 controls IGBT fully controlled bridge 61 through IGBT drive circuit 64.

[0023] When the magnetically controlled reactor is working, a large magnetic flux is generated in columns A, B, C and D of the iron core 1. Voltage and current are induced in columns A and B. After being processed by the excitation circuit 6, they are supplied to the excitation coil 5 to generate DC magnetic flux. By changing the excitation current, the state of the magnetically controlled reactor can be changed, resulting in a controllable inductance value and capacity.

[0024] Auxiliary coil 4 draws power from the magnetically controlled reactor itself to generate an induced electromotive force (EMF). Since the reactor operates in an AC circuit and the magnetic flux in the core column is constantly changing, the generated induced EMF is an AC EMF, which is input into the excitation circuit 6. After rectification and control, a DC excitation current is obtained and connected to the excitation coil 5. The excitation coil 5 generates a magnetomotive force, changing the saturation level of the core and thus changing the permeability μ.

[0025] The permeability of the working coil 2 is controlled by the excitation coil 5, and the equivalent inductance L satisfies L=μSN. 2 / L. Therefore, when the excitation current increases, the iron core 1 saturates. According to the BH characteristic of the iron core 1, the permeability decreases, and the corresponding inductance increases. Conversely, when the excitation current decreases, the iron core 1 desaturates, the permeability increases, and the equivalent inductance of the working coil 2 decreases. This principle is used to control the inductance variation of the reactor. The working coil 2 is connected in parallel to the working AC circuit 3, with opposite winding directions, serving as a reactor.

[0026] In addition, the excitation circuit 6 utilizes a diode rectifier bridge 63, an energy storage capacitor 62, and an IGBT fully controlled bridge 61. The AC current obtained from the auxiliary excitation coil 5 is first rectified into DC by the diode rectifier bridge 63 to power the energy storage capacitor 62, maintaining a constant DC voltage. The output terminal of the energy storage capacitor 62 is connected to the IGBT fully controlled bridge 61, which controls the supply of a larger DC voltage to the DC excitation coil 5. Let the equivalent inductance of the excitation coil 5 be L, then the capacitance C of the capacitor 62 satisfies C = (2πf) / (2πf) 2 L) -1 In the existing excitation circuit, capacitor 62 is absent. Since the excitation coil 5 generates an equivalent inductance value, it hinders current changes and thus reduces the response speed of the magnetically controlled reactor. In this invention, an energy storage capacitor 62 is added. The energy storage capacitor 62 and the inductor form an LC oscillation circuit, enabling rapid charging and discharging and accelerating the response speed.

[0027] like Figure 2 As shown, the induced current obtained from the auxiliary excitation coil 5 is fed into the diode rectifier bridge 63, which rectifies the AC current into DC current to charge the capacitor 62. After charging, the capacitor 62 serves as an equivalent DC power supply, which, through the IGBT fully controlled bridge 61, generates a suitable excitation current. In the control loop of the fully controlled bridge 61, the IGBT duty cycle and PWM pulse width are adjusted to control the instantaneous value of the actual current generated by the rectifier bridge 63. i As a feedback quantity, it is compared with the command current calculated by the controller 65. i ref The difference is calculated, and after being processed by PI closed-loop regulation, the output becomes the PWM control signal required by the switching transistor, which is sent to the IGBT drive circuit 64 to control the IGBT full control bridge 61.

[0028] By controlling the IGBT fully controlled bridge 61, the magnitude of the DC excitation current is adjusted, thereby achieving the purpose of adjusting the inductance and capacity of the magnetically controlled reactor. The magnetically controlled reactor has three states: excitation, operation, and demagnetization. When the magnetically controlled reactor needs rapid excitation and operation, the fully controlled bridge 61 is adjusted so that capacitor 62 supplies power to the excitation coil 5, the excitation coil 5 experiences a forward voltage, and the bias current rises rapidly. When operating, according to the user's requirements for the inductance and capacity of the magnetically controlled reactor, a specific reference excitation current value is calculated, and the current value output by the fully controlled bridge 61 is measured. PI closed-loop control is used to quickly adjust the excitation current to achieve the required current, generating appropriate capacity and inductance values, thus quickly responding to actual needs. When the magnetically controlled reactor needs rapid demagnetization, the fully controlled bridge 61 is adjusted to supply power in reverse, the excitation coil 5 experiences a reverse voltage to charge capacitor 62, and the bias current decreases rapidly. By actively adjusting the IGBT for demagnetization and excitation, the demagnetization speed is faster, energy is not lost, it is more controllable, and it can meet the bidirectional current flow requirements compared with existing demagnetization methods.

[0029] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A fast-response magnetically controlled reactor based on active excitation regulation, characterized by: The system includes an iron core (1) with multiple winding columns. A working coil (2), an auxiliary coil (4), and an excitation coil (5) are wound on the winding columns. The working coil (2) is connected in parallel to the working AC circuit (3). The auxiliary coil (4) and the excitation coil (5) are connected to the excitation circuit (6). The excitation circuit (6) includes a rectifier bridge (63) whose input terminal is connected to the auxiliary coil (4). The output terminal of the rectifier bridge (63) is connected to the input terminal of the fully controlled bridge (61). The output terminal of the fully controlled bridge (61) is connected to the excitation coil (5). An energy storage circuit is connected in parallel between the rectifier bridge (63) and the fully controlled bridge (61). The core (1) has four winding posts, the excitation coil (5) is a single coil, the working coil (2) and the auxiliary coil (4) are both double coils and are wound in opposite directions. The excitation coil (5) is wound on one end of the two middle winding posts, the double coils in the working coil (2) are wound on the other end of the two middle winding posts respectively, and the double coils in the auxiliary coil (4) are wound on the first and last winding posts respectively. The fully controlled bridge (61) is an IGBT fully controlled bridge (61) and also includes a controller (65). The controller (65) controls the IGBT fully controlled bridge (61) through the IGBT drive circuit (64).

2. A method using the fast-response magnetically controlled reactor based on active excitation regulation as described in claim 1, characterized in that: By controlling the IGBT full control bridge (61), the magnitude of the DC excitation current is adjusted to regulate the inductance and capacity of the magnetically controlled reactor.

3. The method for a fast-response magnetically controlled reactor based on active excitation regulation according to claim 2, characterized in that: The controller (65) adjusts the IGBT duty cycle and PWM pulse width to convert the instantaneous current value generated by the rectifier bridge (63) into the current value of the rectifier bridge (63). i As a feedback quantity, it corresponds to the command current issued by the controller (65). i ref The difference is processed by PI closed-loop regulation and output as a PWM control signal, which is sent to the IGBT drive circuit (64) to control the IGBT full control bridge (61).

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