Generator controller of a constant frequency ac power supply system and control method thereof

Abstract

This application provides a generator controller control method for a constant frequency AC power system to solve the engagement problem caused by the weak constant load capacity of the constant frequency AC power system at low speeds. The method includes: periodically acquiring the generator excitation voltage, frequency, generator control switch signal, main contactor signal, and generator three-phase current obtained through the current transformer; when it is determined that the generator excitation voltage and frequency are less than predetermined values, and the generator control switch signal and main contactor signal are both on, and any current in the three-phase current transformer is less than a predetermined value, a chopping indicator is generated; based on the chopping indicator, the voltage regulator is controlled to disable operation, so that the excitation current in the generator excitation circuit undergoes a chopping process to adjust the duty cycle of the excitation current, thereby reducing the generator three-phase AC output voltage, reducing the load power, increasing the generator frequency, and causing the constant frequency AC power system to enter underfrequency protection, thus solving the main contactor engagement problem.

Description

Technical Field

[0001] This application belongs to the field of generator controller technology, and specifically relates to a generator controller and control method for a constant frequency AC power supply system. Background Technology

[0002] With the increasing demand for aviation power systems and the growing complexity of control methods, the control methods of power systems have evolved from the earliest analog circuit controllers to the current digital controllers. The design of digital controllers plays a decisive role in the realization of the functions of the entire power system and the stability of power supply.

[0003] A certain type of generator controller, together with a certain type of oil-cooled AC generator and current transformers, forms a constant frequency AC power generation system (or constant frequency AC power supply system). This system provides 115 / 200V, 400Hz constant frequency AC power, conforming to GJB181-86 requirements, to the electrical equipment on the aircraft. The generator controller is used for automatic regulation of the point voltage and adjusts the excitation current to ensure the generator outputs compliant three-phase AC power. It also features control, protection, self-detection, fault isolation, and communication functions. When the generator of the constant frequency AC power generation system is generating electricity at a low speed (less than 9000 rpm / min), if the load of the on-board electrical equipment suddenly increases to 25kVA~30kVA, the generator frequency will drop below the strong underfrequency point (330Hz). At this time, the strong underfrequency fault protection is activated. The generator controller detects the strong underfrequency protection and disconnects the feeder main contactor and excitation relay. At this time, the sudden increase in load is relieved, the generator frequency returns to the normal range, the generator controller reconnects the excitation relay and feeder main contactor, and the load of the electrical equipment suddenly increases again to 25kVA-30kVA, causing the feeder main contactor to close.

[0004] Existing generator controllers lack corresponding control and protection strategies for the engagement problem caused by the weak constant load capacity of constant frequency AC power systems at low speeds. Summary of the Invention

[0005] The purpose of this application is to provide a generator controller and control method for a constant frequency AC power system to solve or mitigate at least one of the problems in the prior art.

[0006] The technical solution of this application is: a generator controller control method for a constant frequency AC power system, used to solve the engagement problem caused by the weak constant load capacity of the constant frequency AC power system at low speeds, characterized in that the method includes:

[0007] Periodically acquire generator excitation voltage, frequency, generator control switch signals, main contactor signals, and generator three-phase current obtained through the current transformer;

[0008] When it is determined that the generator excitation voltage is less than a predetermined voltage value, the frequency is less than a predetermined frequency value, the generator control switch signal and the main contactor signal are both on, and any current in the three mutual inductors is less than a predetermined current value, a chopping indicator is generated.

[0009] According to the chopper indicator, the voltage regulator of the generator controller is disabled, causing the excitation current in the generator excitation circuit to undergo a chopping process to adjust the duty cycle of the excitation current, thereby reducing the three-phase AC output voltage of the generator, reducing the load power of the constant frequency AC power system, increasing the generator frequency to above 330Hz, the strong underfrequency fault point, and causing the constant frequency AC power system to enter underfrequency protection to resolve the main contactor engagement.

[0010] Furthermore, during the chopping process of the excitation current in the generator excitation circuit, when the chopping indicator is present, and when it is determined that the generator excitation voltage is less than a predetermined voltage value and the frequency is less than a predetermined frequency value, and at the same time it is determined that the generator control switch signal and the main contactor signal are both on, and when it is determined that any current among the three mutual inductors is less than a predetermined current value, the chopping indicator count increases.

[0011] Furthermore, when the chopping duration exceeds a predetermined time and the chopping flag count reaches a predetermined count value, a fault protection flag is generated.

[0012] Furthermore, based on the aforementioned fault protection indicator, the generator controller controls the main contactor and the generator's excitation relay to disconnect, thereby de-exciting the generator; and / or

[0013] Based on the fault protection indicator, the generator controller controls the generator control switch to disconnect so that the constant frequency AC power system can be reset.

[0014] Furthermore, if the chopping duration exceeds the predetermined time and the chopping count does not reach the predetermined count value, the chopping duration and chopping count are reset, and the chopping flag is cleared.

[0015] Furthermore, when the chopper count equals the product of the previous cycle chopper count and the excitation current duty cycle coefficient, if the generator excitation voltage is less than the predetermined voltage value, the frequency is lower than the predetermined frequency value, the generator control switch and the main contactor are closed, and any one phase current of the three mutual inductors is greater than the predetermined current value, then the voltage regulator of the generator controller will resume operation.

[0016] In addition, this application also provides a generator controller for a constant frequency AC power system, the generator controller including a voltage regulator, the generator controller controlling the working state of the voltage regulator according to the generator controller control method for a constant frequency AC power system as described in any of the above claims.

[0017] The generator controller control method for constant frequency AC power systems provided in this application is based on controlling the working state of the voltage regulator to adjust the performance of the constant speed transmission device when a sudden heavy load is applied at low speed, which causes the frequency to decrease. This effectively solves the problem of the main contactor engaging in the constant frequency AC power system under such low speed conditions and achieves protection for the constant frequency AC power system. Attached Figure Description

[0018] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0019] Figure 1 This is a schematic diagram of the constant frequency AC power generation system in this application.

[0020] Figure 2 This is a schematic diagram of the generator controller control method of this application.

[0021] Figure 3 This is a schematic diagram of the generator controller control process of this application.

[0022] Figure 4 This is a schematic diagram illustrating the chopping process performed by the generator controller of this application.

[0023] Figure 5 This is the chopper background processing function for the generator controller in this application. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0025] like Figure 1 The diagram shows a constant-frequency AC power generation system provided in an embodiment of this application. This system mainly includes: a generator controller; a generator with generator transformers, a voltage regulating point, and a permanent magnet motor; and transformers for sensing the generator output current. The generator controller can receive generator speed signals, generator control switch (GCS) signals, overvoltage detection signals, wheel load signals, generator voltage regulating point signals, generator current signals, and main contactor (GC) signals. The generator controller controls the generator to generate electricity based on these signals. The generator output current is connected to the AC busbar through three-phase (A, B, C) transformers and the main contactor, thereby supplying power to the electrical equipment in the load area. The generator controller contains a voltage regulator. When the voltage regulator in the generator controller is turned on, it senses the voltage regulating point voltage within the generator, thereby controlling the on / off state of the MOSFET at the end of the excitation circuit to control the excitation current in the generator excitation circuit.

[0026] In this constant-frequency AC power generation system, the reason for the main contactor engaging is the short delay time (500ms) and lack of self-locking of the strong underfrequency protection. Under low-speed, high-load conditions (for example, in this embodiment of the application, when the generator is generating electricity at a low speed of less than 9000 rpm / min, the load of the on-board electrical equipment suddenly increases to 25kVA-30kVA), due to the low load-carrying capacity of the constant-speed transmission device, the generator frequency suddenly drops to between 200Hz and 300Hz and lasts for more than 500ms, thus triggering the strong underfrequency fault protection. The strong underfrequency fault protection causes the generator controller to disconnect the feeder main contactor and excitation relay, suddenly removing the load. The generator frequency then returns to the normal range, and the generator controller reconnects the excitation relay and feeder main contactor. The load of the electrical equipment suddenly increases again, causing the feeder main contactor to engage.

[0027] To address this issue, this application provides a generator controller control method for a constant-frequency AC power system that suffers from engagement problems due to weak constant-load capacity at low speeds. This method controls the generator excitation current duty cycle by adjusting the duty cycle coefficient to regulate the time the generator controller's voltage regulator is off-duty, thereby regulating the generator's three-phase output voltage and controlling the load power of the power generation system. This method also matches the performance of the constant-speed transmission device at low speeds, adjusts the frequency of the constant-speed transmission device, and protects the power system.

[0028] like Figure 2 As shown, the generator controller control method for a constant frequency AC power system provided in this application includes the following process:

[0029] S1 periodically acquires the generator excitation voltage, frequency, generator control switch, main contactor status signals, and generator three-phase current obtained through the current transformer.

[0030] S2. Determine whether the generator excitation voltage is less than the predetermined voltage value and frequency is less than the predetermined frequency value. At the same time, determine whether the generator control switch signal and the main contactor signal are both in the ON state, and determine whether any current in the three mutual inductors is less than the predetermined current value. If all the above conditions are met, generate a chopping mark.

[0031] S3. When the chopping indicator is present, the voltage regulator of the generator controller is disabled, causing the excitation current in the generator excitation circuit to undergo a chopping process to adjust the duty cycle of the excitation current, thereby reducing the three-phase AC output voltage of the generator (above 104V at the undervoltage fault point), reducing the load power of the constant frequency AC power system to match the performance of the constant speed transmission device at this speed, increasing the generator frequency above the strong underfrequency fault point, and causing the constant frequency AC power system to enter underfrequency protection to solve the main contactor engagement problem.

[0032] like Figures 3 to 5As shown, the generator controller starts running after power-on. First, it determines the reset type and number of resets, then performs a power-on bit. After the detection is complete, it initializes global variables and discrete outputs, and starts a timer. In this embodiment, the timer duration is set to 8ms. The generator controller executes periodic tasks as needed. If no task timeout occurs, the generator controller will execute periodic tasks according to the timer's set intervals. These tasks include data acquisition, fault detection, communication, bit operation, bit maintenance, data recording, and downloading. The generator excitation voltage, frequency, generator control switch signals, main contactor signals, and three-phase mutual inductance currents are all monitored during these periodic tasks.

[0033] After the generator controller completes its periodic task (execution time is 2-3ms), it sets the task status to background running state and loops through background task processing, waiting for a timer interrupt. When the timer delay expires, it enters a timer interrupt to set the task status. If the previous periodic task has been completed (i.e., the periodic task end flag has been set), the task status is set to periodic task processing state; otherwise, the task status is set to task timeout state. The determination of whether to enter periodic task processing or task timeout processing is based on the task status.

[0034] After the generator controller completes its main task, it enters a background task processing loop for approximately 5-6 ms. During this background task processing, no other tasks are executed. To avoid affecting the execution of periodic tasks, chopping processing begins after the periodic tasks are completed. During the background task processing, the operation of the voltage regulator in the generator controller can be controlled to adjust the duty cycle of the excitation current.

[0035] During the chopping process by the generator controller, the controller continuously and periodically acquires data, including generator excitation voltage, frequency, generator control switch and main contactor status, and mutual inductance current. When the excitation voltage is detected to be below 27.5V and the frequency below 375Hz, and the generator control switch GCS input signal is on, the positive terminal of the feeder main contactor is on, and any phase of the three mutual inductor current is greater than 25A, a chopping flag is generated and counting begins. At this time, the voltage regulator is disabled, a chopping fault delay begins, and the generator controller begins executing the chopping process, looping through background task processing. When the chopping flag exists, the background chopping count is incremented by 1.

[0036] When the generator controller performs chopping processing, if the chopping delay time reaches 6 seconds and the chopping count reaches 280 times, a fault protection flag is set. Once the fault protection flag is set, the generator controller controls the excitation relay and feeder main contactor to disconnect, de-exciting the generator and cutting off contactor control. Alternatively, the generator controller can control the generator control switch GCS to disconnect or reconnect to reset the product, thereby protecting the power generation system.

[0037] If, during the chopping process by the generator controller, the chopping delay time reaches 6 seconds but the chopping count has not reached 280, then the chopping delay and chopping count values ​​are reset, and the chopping flag is cleared.

[0038] During the chopping process of the generator controller, when the chopping count is detected to be equal to the chopping count of the previous cycle multiplied by the duty cycle coefficient, if the excitation voltage is below 27.5V and the frequency is below 375Hz, and at the same time the generator control switch GCS input signal is on, the positive terminal of the feeder main contactor is on, and any one phase of the three mutual inductor current is greater than 25A, then the voltage regulator operation is restored.

[0039] The generator controller control method for constant frequency AC power systems provided in this application is based on controlling the working state of the voltage regulator to adjust the performance of the constant speed transmission device when a sudden heavy load is applied at low speed, which causes the frequency to decrease. This effectively solves the problem of the main contactor engaging in the constant frequency AC power system under such low speed conditions and achieves protection for the constant frequency AC power system.

[0040] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A generator controller control method for a constant frequency AC power system, used to solve the engagement problem caused by the weak constant load capacity of the constant frequency AC power system at low speeds, characterized in that... The method includes: Periodically acquire generator excitation voltage, frequency, generator control switch signals, main contactor signals, and generator three-phase current obtained through the current transformer; When it is determined that the generator excitation voltage is less than a predetermined voltage value, the frequency is less than a predetermined frequency value, the generator control switch signal and the main contactor signal are both on, and any current in the three mutual inductors is less than a predetermined current value, a chopping indicator is generated. According to the chopper indicator, the voltage regulator of the generator controller is disabled, causing the excitation current in the generator excitation circuit to undergo a chopping process to adjust the duty cycle of the excitation current, thereby reducing the three-phase AC output voltage of the generator, reducing the load power of the constant frequency AC power system, increasing the generator frequency to above 330Hz, the strong underfrequency fault point, and causing the constant frequency AC power system to enter underfrequency protection to resolve the main contactor engagement.

2. The generator controller control method for a constant frequency AC power supply system as described in claim 1, characterized in that, During the chopping process of the excitation current in the generator excitation circuit, when the chopping indicator is present, and it is determined that the generator excitation voltage is less than a predetermined voltage value and the frequency is less than a predetermined frequency value, and it is also determined that the generator control switch signal and the main contactor signal are both on, and it is determined that any current among the three mutual inductors is less than a predetermined current value, the chopping indicator count increases.

3. The generator controller control method for a constant frequency AC power supply system as described in claim 2, characterized in that, When the chopping duration exceeds the predetermined time and the chopping flag count reaches the predetermined count value, a fault protection flag is generated.

4. The generator controller control method for a constant frequency AC power supply system as described in claim 3, characterized in that, Based on the fault protection indicator, the generator controller controls the main contactor and the generator's excitation relay to disconnect, thereby de-exciting the generator; and / or Based on the fault protection indicator, the generator controller controls the generator control switch to disconnect so that the constant frequency AC power system can be reset.

5. The generator controller control method for a constant frequency AC power supply system as described in claim 2, characterized in that, If the chopping duration exceeds the predetermined time and the chopping count does not reach the predetermined count value, then the chopping duration and chopping count are reset, and the chopping flag is cleared.

6. The generator controller control method for a constant frequency AC power supply system as described in claim 2, characterized in that, When the chopper count equals the product of the previous cycle chopper count and the excitation current duty cycle coefficient, if the generator excitation voltage is less than the predetermined voltage value, the frequency is lower than the predetermined frequency value, the generator control switch and main contactor are closed, and any one phase current of the three mutual inductors is greater than the predetermined current value, then the voltage regulator of the generator controller will resume operation.

7. A generator controller for a constant frequency AC power supply system, characterized in that, The generator controller includes a voltage regulator, and the generator controller controls the working state of the voltage regulator according to the generator controller control method of the constant frequency AC power system as described in any one of claims 1 to 6.

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