Generator short circuit excitation circuit

Abstract

This invention discloses a generator short-circuit excitation circuit. Two current transformers are installed on the generator stator winding output line. The secondary sides of the two current transformers are connected in series and then connected to a three-phase transformer. The output of the three-phase transformer, after being rectified, is connected in parallel with the collector and emitter of a transient suppression diode, a Zener diode, and a Darlington transistor. A Zener diode is connected in parallel between the collector and base of the Darlington transistor, and a resistor is connected in parallel between the emitter and base. The collector of the Darlington transistor is connected in series with a diode and then to the positive terminal of the excitation power supply. The base of the Darlington transistor is connected in series with a Zener diode and a resistor and then to the positive terminal of the excitation power supply. The emitter of the Darlington transistor is connected to the negative terminal of the excitation power supply. This invention switches the generator from voltage source excitation mode to current source excitation mode when a short-circuit fault occurs, ensuring sufficient short-circuit capacity and enabling rapid operation of relay protection devices, thereby improving the power supply reliability of the power system.

Description

Technical Field

[0001] This invention belongs to the field of synchronous generator excitation systems, specifically relating to a generator short-circuit excitation circuit, which is suitable for voltage source type phase compound excitation regulators. Background Technology

[0002] Synchronous generators are the core of electromechanical energy conversion and an indispensable component of shipboard electrical systems. They integrate rotation and stillness, electromagnetic changes and mechanical motion, converting mechanical energy into electrical energy to supply the ship's electrical system. Together with the excitation regulation system, prime mover, and speed control system, they provide the main source of electrical energy for the ship's electrical system.

[0003] Short-circuit protection of synchronous generators is usually achieved by external protection devices detecting the output current. However, when a generator experiences a short-circuit fault, the terminal voltage is very low. Consequently, the self-excited excitation power supply is low, and the output current is insufficient to activate the relay protection device, thus affecting the power supply quality of the power system. Summary of the Invention

[0004] This invention provides a generator short-circuit excitation circuit that switches the generator from voltage source excitation mode to current source excitation mode when a short-circuit fault occurs, ensuring that the generator has sufficient short-circuit capacity, enabling the relay protection device to act quickly, and improving the power supply reliability of the power system.

[0005] The technical solution adopted by this invention to solve its technical problem is as follows: a generator short-circuit excitation circuit, including a current transformer I and a current transformer II installed on the output line of the generator stator winding. The secondary sides of the current transformer I and the current transformer II are connected in series and then connected to a three-phase transformer. The output of the three-phase transformer is rectified and then connected in parallel with a transient suppression diode, a Zener diode I, and the collector and emitter of a Darlington transistor. A Zener diode II is connected in parallel between the collector and the base of the Darlington transistor. A resistor I is connected in parallel between the emitter and the base of the Darlington transistor. The collector of the Darlington transistor is connected in series with a diode and then connected to the positive terminal of the excitation power supply. The base of the Darlington transistor is connected in series with a Zener diode III and a resistor II and then connected to the positive terminal of the excitation power supply. The emitter of the Darlington transistor is connected to the negative terminal of the excitation power supply.

[0006] The generator short-circuit excitation circuit described above uses the three-phase current induced on the secondary side of current transformer one and current transformer two as the input power supply for the excitation circuit.

[0007] The generator short-circuit excitation circuit described above uses a star connection for both the input and output windings of its three-phase transformer.

[0008] The advantages and positive effects of this invention are as follows: When the generator is running normally, the excitation circuit of this invention forms a loop through the Darlington tube during short circuit, which does not affect the normal operation of the excitation circuit; when the generator is short-circuited, the excitation circuit of this invention obtains power from the current transformer and outputs current to the excitation winding, ensuring that the generator continues to output a large current during short circuit, thereby causing the protection circuit breaker to operate.

[0009] This invention bypasses the complex short-circuit detection process, uses a simple analog circuit, operates quickly, and improves the power supply reliability of the power system. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the structure of the present invention.

[0011] Explanation of markings in the diagram: TA1—Current transformer one, TA2—Current transformer two, T002—Three-phase transformer, Z2—Rectifier, DZ1—Transient suppression diode, D1—Zenith diode one, D2—Zenith diode two, D3—Zenith diode, D4—Diode, Q1—Darlington diode, R1—Resistor one, R2—Resistor two. Detailed Implementation

[0012] The present invention will now be described in further detail with reference to the accompanying drawings.

[0013] like Figure 1 As shown, this invention discloses a generator short-circuit excitation circuit. Current transformer TA1 and current transformer TA2 are installed on the output line of the generator stator winding. The secondary sides of current transformer TA1 and current transformer TA2 are connected in series and then connected to a three-phase transformer T002. The input and output windings of the three-phase transformer T002 are both connected in a star configuration. The output of the three-phase transformer T002 is rectified by rectifier Z2 and then connected to transient suppression diode DZ1 and Zener diode DZ1. 1. The collector and emitter of Darlington transistor Q1 are connected in parallel. A Zener diode D2 is connected in parallel between the collector and base of Darlington transistor Q1. A resistor R1 is connected in parallel between the emitter and base of Darlington transistor Q1. The collector of Darlington transistor Q1 is connected in series with diode D4 and then connected to the positive terminal of the excitation winding. The base of Darlington transistor Q1 is connected in series with Zener diode D3 and resistor R2 and then connected to the positive terminal of the excitation winding. The emitter of Darlington transistor Q1 is connected to the negative terminal of the excitation winding.

[0014] When the generator has an output current, the three-phase current induced on the secondary side of the current transformer TA1 and the current transformer TA2 on the output line will be used as the excitation power supply for short-circuit excitation after passing through the three-phase transformer T002 and the rectifier Z2.

[0015] When the generator is running under normal load, the excitation power supply is obtained by rectifying the generator output voltage through a three-phase transformer. At this time, the excitation power supply is connected in parallel across the base and emitter terminals of Darlington transistor Q1. Darlington transistor Q1 is turned on, and the excitation power supply forms a circuit through Darlington transistor Q1. It does not output current to the excitation winding and has no effect on the generator excitation system. The generator is operating normally.

[0016] When a generator experiences a short circuit, the excitation power supply, derived from the generator terminal voltage, decreases. Consequently, the excitation power supply also decreases. This excitation power supply is connected in parallel across the base and emitter of Darlington transistor Q1, causing Q1 to cut off. The short-circuit excitation power supply then forms a loop with the excitation winding via Zener diodes D2 and D3 and resistor R2, continuously supplying excitation current to the winding. This changes the generator's excitation mode from voltage source to current source. This ensures sufficient short-circuit capacity for the generator, enabling rapid operation of relay protection devices and improving the reliability of the power supply system.

[0017] Obviously, the embodiments described above are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A generator short-circuit excitation circuit, characterized in that: This includes current transformer 1 (TA1) and current transformer 2 (TA2) installed on the output line of the generator stator winding. The secondary sides of current transformer 1 (TA1) and current transformer 2 (TA2) are connected in series and then connected to a three-phase transformer (T002). The three-phase current induced on the secondary sides of current transformer 1 (TA1) and current transformer 2 (TA2) is used as the input power supply after passing through the three-phase transformer (T002) and rectifier (Z2). The input and output windings of the three-phase transformer (T002) are both connected in a star configuration. The output of the three-phase transformer (T002) is then rectified by rectifier (Z2) and connected to... The collectors and emitters of the transient suppression diode (DZ1), Zener diode 1 (D1), and Darlington transistor (Q1) are connected in parallel. Zener diode 2 (D2) is connected in parallel between the collector and base of Darlington transistor (Q1). Resistor 1 (R1) is connected in parallel between the emitter and base of Darlington transistor (Q1). The collector of Darlington transistor (Q1) is connected in series with diode (D4) and then connected to the positive terminal of the excitation power supply. The base of Darlington transistor (Q1) is connected in series with Zener diode 3 (D3) and resistor 2 (R2) and then connected to the positive terminal of the excitation power supply. The emitter of Darlington transistor (Q1) is connected to the negative terminal of the excitation power supply.

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