A fast switching emergency protection system for aircraft engine testing

Abstract

The present application discloses a fast switching emergency protection system for aircraft engine testing, including: a fast switching unit, which is used to quickly disconnect a DC load and switch the DC load to an emergency protection load according to a switching instruction issued by a controller; a measuring unit, which is used to measure signals such as the engine gas turbine speed, free turbine speed, AC voltage and current, DC voltage and current; a controller, which is used to make a fault judgment on the system according to the measurement data collected by the measuring unit and to issue a switching instruction to the fast switching unit accordingly when a fault occurs; a monitoring system, which is used to monitor the parameters and operating status of the rectifier, bus, and DC load system for display; an emergency protection load, which is connected to the fast switching unit circuit, is used to provide an emergency protection load when the hybrid power system is in a large state and the load is suddenly lost. The present application realizes overspeed protection for the turboshaft engine hybrid power system test to avoid accidents such as turbine blade breakage and flying out.

Description

Technical Field

[0001] The present application relates to the technical field of aero-engines, and in particular, to a fast-switching emergency protection system for aero-engine testing. Background Art

[0002] The principles and components of existing hybrid power systems are as follows: Figure 1 As shown in the figure, it includes a turboshaft aircraft engine, a permanent magnet generator, a rectifier, a DC load system, a state monitoring system, etc. The turboshaft engine is used as the prime mover, and its output shaft drives the generator. The engine generates AC power, which is stabilized by the rectifier and output to the resistive load for consumption. The state monitoring system is used to monitor the parameters and operating status of the rectifier, busbar, and DC load system.

[0003] When testing the hybrid power system of an aircraft engine, the aircraft engine acts as the prime mover to drive the generator to generate electrical energy, which is consumed by the electrical load. However, there is a potential risk during the system test: when the hybrid power system is in a high state, if the load is suddenly lost, the aircraft engine will overspeed and cause the turbine blades to break.

[0004] Obviously, the existing hybrid power system monitors the status of power generation and load systems, but does not consider protection measures and cannot solve the problem of turbine blade rupture caused by aircraft engine overspeed. Summary of the invention

[0005] The present application provides a fast-switching emergency protection system for aircraft engine testing to solve the technical problem that the existing aircraft engine hybrid power system test has no overspeed protection function and there are great safety risks in the test.

[0006] The technical solutions adopted in this application are as follows:

[0007] A fast switching emergency protection system for aircraft engine testing, comprising:

[0008] A fast switching unit is connected to the generator, the rectifier and the emergency protection load circuit respectively, and is used to quickly disconnect the DC load and switch the DC load to the emergency protection load according to a switching instruction issued by the controller;

[0009] The measuring unit is respectively connected to the turboshaft engine, the generator, the rectifier, and the DC load circuit, and is used to measure the engine gas turbine speed, the free turbine speed, the AC voltage and current, the DC voltage and current, the rectifier fault digital signal, and the DC load system fault digital signal;

[0010] A controller, connected to the fast switching unit, the measuring unit and the monitoring system circuit respectively, for judging the system fault according to the measurement data collected by the measuring unit and issuing a switching instruction to the fast switching unit accordingly when a fault occurs;

[0011] A monitoring system, which is in communication with the controller and is used to monitor the parameters and operating status of the rectifier, busbar, and DC load system for parameter display;

[0012] The emergency protection load is connected to the fast switching unit circuit and is used to provide an emergency protection load when the hybrid power system is in a large state and the load is suddenly lost, so as to prevent the turbine blades from breaking due to overspeed of the aircraft engine.

[0013] Furthermore, the fast switching unit includes a switching switch, which is an IGPT tube group. The IGPT tube groups are respectively installed on the DC load circuit and the emergency protection load circuit to form an interlocking relationship.

[0014] Furthermore, the fast switching unit includes a high-power solid-state relay.

[0015] Furthermore, the controller adopts a NICRIO controller.

[0016] Furthermore, the monitoring system is connected to the controller via LAN communication.

[0017] Furthermore, the LAN communication includes WIFI, Bluetooth, ZigBee, and Lora.

[0018] Furthermore, the emergency protection load is consistent with the DC load in size.

[0019] Furthermore, the emergency protection load includes: air-cooled AC load, air-cooled DC load with rectifier, air-cooled AC load, air-cooled DC load with rectifier, water-cooled AC load, water-cooled DC load with rectifier, electric dynamometer, eddy current dynamometer, and grid-connected load.

[0020] Further, the method of performing fault judgment on the system according to the measurement data collected by the measurement unit and issuing a switching instruction to the fast switching unit accordingly when a fault occurs specifically includes the steps of:

[0021] Acquire measurement data collected by the measurement unit, including gas turbine speed, free turbine speed, AC voltage, and AC current;

[0022] When the engine is in a set power state above the air idle, if a fault is detected, a switching instruction is immediately sent to the fast switching unit for protection. The set power state is specifically a state of more than 80% of the full power of the engine.

[0023] Furthermore, when the engine is in a set power state above the air idle, if a fault is detected, a switching instruction is immediately sent to the fast switching unit for protection, specifically including the steps of:

[0024] Engine status judgment: When the gas turbine speed ≥ A, free turbine speed = B, AC voltage ≥ C, AC current ≥ G, the engine is judged to be in a set power state above the air idle, where A is the minimum set value of the gas turbine speed; B is the set value of the free turbine speed; C is the minimum set value of the generator output AC voltage; G is the minimum set value of the generator output AC current;

[0025] Fault judgment: If the DC current ≤ H, or the DC voltage ≤ J, or a rectifier fault digital signal is received, or a DC load system fault digital signal is received, it is considered to be a fault, where H is the minimum setting value of the DC current, and J is the minimum setting value of the DC voltage;

[0026] Send command: immediately send a switching command to the fast switching unit for protection.

[0027] Compared with the prior art, this application has the following beneficial effects:

[0028] The present application provides a fast-switching emergency protection system for aircraft engine testing, comprising a fast-switching unit, a measuring unit, a controller, a monitoring system, and an emergency protection load. The system performs fault judgment based on measurement data collected by the measuring unit and issues a switching instruction to the fast-switching unit accordingly when a fault occurs. The fast-switching unit quickly disconnects a DC load and switches the DC load to an emergency protection load according to the switching instruction issued by the controller. When the DC load is suddenly and abnormally unloaded in a large engine state, the engine speed can be prevented from abnormally increasing, causing the centrifugal force of the blades to exceed the limit, thereby realizing overspeed protection for the turboshaft engine hybrid power system test, so as to avoid test accidents in which turbine blades break and fly out. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0030] Figure 1 It is a schematic diagram of the principle of the aircraft engine test system;

[0031] Figure 2 This is a schematic diagram of the principle of a fast-switching emergency protection system for aircraft engine testing according to a preferred embodiment of the present application;

[0032] Figure 3 It is the software layered architecture of the fast switching emergency protection system of the preferred embodiment of the present application. DETAILED DESCRIPTION

[0033] The embodiments of the present application are described in detail below in conjunction with the accompanying drawings, but the present application can be implemented in a variety of different ways defined and covered below.

[0034] like Figure 2 As shown, the preferred embodiment of the present application provides a fast switching emergency protection system for aircraft engine testing, comprising:

[0035] A fast switching unit is connected to the generator, the rectifier and the emergency protection load circuit respectively, and is used to quickly disconnect the DC load and switch the DC load to the emergency protection load according to a switching instruction issued by the controller;

[0036] The measuring unit is respectively connected to the turboshaft engine, the generator, the rectifier, and the DC load circuit, and is used to measure the engine gas turbine speed, the free turbine speed, the AC voltage and current, the DC voltage and current, the rectifier fault digital signal, and the DC load system fault digital signal;

[0037] A controller, connected to the fast switching unit, the measuring unit and the monitoring system circuit respectively, for judging the system fault according to the measurement data collected by the measuring unit and issuing a switching instruction to the fast switching unit accordingly when a fault occurs;

[0038] A monitoring system, which is in communication with the controller and is used to monitor the parameters and operating status of the rectifier, busbar, and DC load system for parameter display;

[0039] The emergency protection load is connected to the fast switching unit circuit and is used to provide an emergency protection load when the hybrid power system is in a large state (the engine gas turbine speed is greater than 80%) and the load is suddenly lost, so as to prevent the turbine blades from breaking due to overspeeding of the aircraft engine.

[0040] There are gas turbines and free turbines in the structure of aircraft engines. The gas turbine rotates by gas expansion, and the free turbine rotates the turbine blades by gas blowing. There is no shaft connection between them, corresponding to the gas turbine speed and the free turbine speed respectively. The engine controller generally works in a closed loop, that is, the constant rotation mode of the free turbine speed. Under normal circumstances, the speed is stable, and the power output of the engine and the added load (such as the generator + DC load in hybrid power) should be balanced. Under a certain working condition: the engine is in the maximum power state, the speed is stable, and suddenly for some reason, the load suddenly disappears. At this time, the engine output power is still in the maximum power state, and its load torque is 0, P=T×N / 9550, the free turbine speed N must rush up, exceeding the centrifugal force of the blades, and the blades will be thrown out in a very short time. Of course, the engine controller will definitely automatically reduce the fuel supply, but it will be of no avail, because the oil reduction adjustment takes time, and the blades have been damaged at this time. The main factors leading to this situation are: component damage of the rectifier and DC load equipment, system loss of control and operational errors, which cause abnormal load shedding. The specific electrical manifestations are: the rectifier output voltage and current are abnormally 0, and the DC load voltage and current are 0.

[0041] To this end, the present embodiment provides a fast-switching emergency protection system for aircraft engine testing, including a fast-switching unit, a measuring unit, a controller, a monitoring system, and an emergency protection load. In a turbine power generation system, protecting the engine from damage is of paramount importance. The fast-switching emergency protection system is used when the DC load is suddenly abnormally unloaded when the engine is in a large state, the engine speed will rise, and the centrifugal force of the blades exceeds the limit. The fast-switching emergency protection system is essentially a disturbance-free switching system that maintains a power balance relationship between the engine output power and the load. Even if the DC load is abnormal, the engine will not feel the abnormality to avoid overspeed. The fast-switching emergency protection system includes a fast-switching unit and an emergency protection load. The main indicator is the switching time, which realizes functions such as millisecond switching, parameter display, and data transmission. Ultimately, it serves as a fast-switching emergency protection system to prevent turbine blades from breaking and flying out.

[0042] To sum up, the present embodiment performs fault judgment on the system based on the measurement data collected by the measurement unit and issues a switching instruction to the fast switching unit accordingly when a fault occurs. The fast switching unit quickly disconnects the DC load and switches the DC load to the emergency protection load according to the switching instruction issued by the controller. When the DC load is suddenly and abnormally unloaded when the engine is in a large state, it can avoid the abnormal increase in engine speed causing the centrifugal force of the blades to exceed the limit, thereby realizing overspeed protection for the turboshaft engine hybrid power system test, so as to avoid the occurrence of test accidents such as turbine blades breaking and flying out.

[0043] Preferably, the fast switching unit includes a switching switch, and the switching switch is an IGPT tube group. The IGPT tube groups are respectively installed on the DC load circuit and the emergency protection load circuit to form an interlocking relationship.

[0044] The fast switching unit of this embodiment adopts IGPT as a switching switch, which has a simple structure and is easy to control, thereby ensuring that the action time of the fast switching unit reaches the nanosecond level when performing load switching, so as to avoid the test accident of the turbine blade breaking and flying out. Moreover, since the IGPT pipe group is respectively installed on the DC load circuit and the emergency protection load circuit and forms an interlocking relationship, the erroneous switching of the DC load and the emergency protection load is also avoided.

[0045] Preferably, the fast switching unit comprises a high-power solid-state relay, which has the advantages of high reliability, long life, high sensitivity, low control power, good electromagnetic compatibility, fast switching, and low electromagnetic interference.

[0046] Preferably, the controller adopts a NICRIO controller.

[0047] Preferably, the monitoring system is connected to the controller via LAN communication, and the LAN communication includes WIFI, Bluetooth, ZigBee, and lora.

[0048] Preferably, the emergency protection load is consistent with the size of the DC load and maintains a synchronous given power value. The benefit and purpose of this is to ensure that the turbine blade speed remains consistent with that before switching after the load is switched when the load is off.

[0049] Preferably, the emergency protection load includes: air-cooled AC load, air-cooled DC load with rectifier, air-cooled AC load, air-cooled DC load with rectifier, water-cooled AC load, water-cooled DC load with rectifier, electric dynamometer, eddy current dynamometer, and grid-connected load.

[0050] Preferably, the method of judging a fault of the system according to the measurement data collected by the measurement unit and issuing a switching instruction to the fast switching unit accordingly when a fault occurs specifically comprises the steps of:

[0051] Acquire measurement data collected by the measurement unit, including gas turbine speed, free turbine speed, AC voltage, and AC current;

[0052] When the engine is in a set power state above the air idle, if a fault is detected, a switching instruction is immediately sent to the fast switching unit for protection. The set power state is specifically a state of more than 80% of the full power of the engine.

[0053] Specifically, when the engine is in a set power state above the air idle, if a fault is detected, a switching instruction is immediately sent to the fast switching unit for protection, which specifically includes the following steps:

[0054] Engine status judgment: When the gas turbine speed ≥ A, free turbine speed = B, AC voltage ≥ C, AC current ≥ G, the engine is judged to be in a set power state above the air idle, where A is the minimum set value of the gas turbine speed; B is the set value of the free turbine speed; C is the minimum set value of the generator output AC voltage; G is the minimum set value of the generator output AC current;

[0055] Fault judgment: If the DC current ≤ H, or the DC voltage ≤ J, or a rectifier fault digital signal is received, or a DC load system fault digital signal is received, it is considered to be a fault, where H is the minimum setting value of the DC current, and J is the minimum setting value of the DC voltage;

[0056] Send command: immediately send a switching command to the fast switching unit for protection.

[0057] In the above embodiments, slow speed refers to the minimum speed state at which the engine can maintain stable operation, ground slow speed refers to the minimum speed state at which the engine can maintain stable operation on the ground, and air slow speed refers to the minimum speed state at which the engine can maintain stable operation under control, wherein the engine speed during air slow speed is greater than that during ground slow speed.

[0058] In order to further realize that the switching time of the fast switching unit does not exceed 5 ms, the preferred embodiment of the present invention will also be optimized from two aspects of software and hardware.

[0059] Software Design

[0060] The software system adopts a hierarchical approach, dividing the program into independent layers according to function and type. The high-level design completes its functions by calling the functions of the low-level, and the low-level also provides services for the higher-level layers. The system software adopts a unified software hierarchical architecture design, dividing the system into user interface layer, data management layer, interface management layer and device driver layer, such as Figure 3 The details are as follows:

[0061] Device driver layer: As a bridge between system hardware and software, the driver layer provides drivers for various bus interface devices and signal interface devices to realize functions such as sending, receiving, and event mode (callback function) receiving;

[0062] Interface management layer: The interface layer mainly manages the Ethernet interface and device signal interface, providing channels for data transmission and command interaction;

[0063] Data management layer: The data management layer mainly completes the tasks of system data generation, data reception and processing, and data storage, and provides a unified encapsulation interface for upper-layer data query and display;

[0064] User interface layer: The user interface layer mainly completes the design of the human-computer interaction interface of the system software. It adopts a graphical human-computer interaction function and can manage the tester to realize the visual operation functions such as data configuration, data query display and data output of the system. It is easy for personnel to view and operate.

[0065] The above-mentioned layered design architecture lays the foundation for further software design and development. The layered design can improve efficiency, make system software debugging and error correction easier, and thus improve the usability and stability of the software.

[0066] The software functions mainly include data configuration, AI acquisition, DIO acquisition and control, and TCPIP communication, as follows:

[0067] Data configuration mainly realizes receiving relevant configuration parameters issued by the monitoring system and completing the coefficient configuration required by the formula.

[0068] AI collection mainly implements relevant data collection and monitoring functions after receiving the monitoring system software startup command.

[0069] DIO acquisition and control mainly realizes automatic switching of the main and auxiliary roads after receiving the start command of the monitoring system software and monitoring reaches the threshold. The digital IO card has a total of 8 channel signals, of which DIO0-DIO3 need to be configured as output. DIO0 is the main output control (the host computer sends configuration instructions to cRIO through network port communication to make it high level), and DIO1 is the auxiliary output control (mutually exclusive with the main output control, and performs logical judgment on the first 14 test data. DIO3 is the program running indicator. When the host computer sends a running instruction to inform the cRIO underlying software to make DIO3 high level, when the host computer sends a stop instruction, DIO0-DIO3 is controlled to be low level.

[0070] TCP / IP communication mainly implements communication of custom protocols, as shown in Table 1.

[0071] Table 1 TCPIP custom communication protocol

[0072] ;

[0073] Hardware Design

[0074] The system uses a CRIO controller, including 1 data acquisition card and 1 digital IO card. The specific parameters are as follows:

[0075] 30 GHz dual-core CPU;

[0076] 2GB DRAM;

[0077] 4GB storage capacity;

[0078] Kintex-7 160T FPGA;

[0079] 4-slot CompactRIO controller.

[0080] NI-9202 synchronous acquisition card, 16 differential input channels with synchronous sampling, ±10 V input range, 10 kS / s / ch, 24 bits;

[0081] The NI-9401 digital IO card is available in three configurations: eight digital inputs, eight digital outputs, or four digital inputs and four digital outputs.

[0082] The signal real-time conditioning unit designed by the system has the following specific parameters:

[0083] DC voltage adjustment range: 0~2000V;

[0084] DC voltage conditioning circuit number: 1;

[0085] DC current adjustment range: 0~2000A;

[0086] Number of DC current conditioning circuits: 1;

[0087] AC voltage adjustment range: 0~1000V;

[0088] Number of AC voltage conditioning circuits: 4 circuits, real-time monitoring of the A-phase and D-phase voltages in the main circuit and the A-phase and D-phase voltages in the auxiliary circuit;

[0089] AC current adjustment range: 0~1000A;

[0090] Number of AC current conditioning circuits: 4 circuits, real-time monitoring of the A-phase and D-phase currents in the main circuit and the A-phase and D-phase currents in the auxiliary circuit;

[0091] Real-time collection of heat sink temperatures of main circuits 1-1 and 1-2;

[0092] Real-time collection of the heat sink temperature of auxiliary circuits 1-1 and 1-2;

[0093] Main circuit, auxiliary circuit, over-temperature and operation status indication;

[0094] Provides the necessary 5V and 24V power supply for the real-time switching unit IGBT control circuit.

[0095] The fast switching unit design includes demand design, IGPT selection and heat dissipation design, IGPT drive design and IGBT absorption design.

[0096] Demand Design

[0097] The generator outputs 2 three-phase electricity, a total of 6 phases, with a maximum voltage output of 705V, a maximum power of 1MW, and a single-phase current of 492A. The generator output is an AC signal. In summary, the Infineon IGBT module FF600R12KE4_E is selected as the control switch. A single IGBT has a withstand voltage of 1200V and a current of 600A. Considering the heat dissipation effect, 2 IGBT modules are selected for each phase switch in parallel. In this way, each set of switches requires 12 IGBT modules, and the two sets of switches require a total of 24 IGBT modules (main circuit and auxiliary circuit).

[0098] IGBT selection and heat dissipation design

[0099] IGBT is a power device with its own voltage drop. When the current is too large, a lot of heat will be generated. Therefore, the IGBT module needs to be cooled by an aluminum heat sink. The IGBT module is fixed on the aluminum heat sink. In order to effectively diffuse the heat and increase the contact reliability, thermal grease is applied on the contact surface between the IGBT module and the heat sink, and then the fan is used for air cooling. Each input and output is led to the input and output port through a cable.

[0100] Because there are many IGBTs and the current is large, the main circuit and the auxiliary circuit are each divided into two parts. Each part is switched by a three-phase switch. In this way, each part consists of 6 IGBTs and 1 heat sink. A total of 24 IGBTs are fixed on 4 heat sinks.

[0101] IGBT driver design

[0102] Considering the convenience of layout and wiring, 6 IGBT drivers are made into 1 control board, which is equivalent to 1 driver controller board for each three-phase switch. The IGBT driver is implemented by Infineon's recommended solution 1EDI40I12AF. 1EDI40I12AF is a single-channel isolated IGBT driver solution that can achieve a 4A current drive capability and an input-to-output isolation voltage of 1200V. Because each IGBT module has 2 IGBT tubes, the drive of each IGBT module is implemented by two 1EDI40I12AFs. The IGBT drive voltage is ±15V. Due to the large current of high-power IGBT drive and the design considering reliability and stability, the VRA2415LD-20WR3 power module of Golden Sun is selected. The VRA2415LD-20WR3 power module can achieve 24V power input and ±15V power output.

[0103] IGBT absorption design

[0104] The switching frequency of the fast switching emergency protection system is low, and the IGBT is flowing through an AC signal. Therefore, the capacitor + varistor method is used to absorb the IGBT module, reduce the impact voltage during the switching process of the IGBT module, and protect the IGBT module. The capacitor uses Rongpu's IGBT-specific non-inductive capacitor, which has high stability, flame-retardant PBT plastic shell, and epoxy resin potting with good sealing. The specification parameters are 2.5uF and 1200VDC voltage. The varistor uses 25D471KJ, and each IGBT module has two in series, which can protect the voltage to 940V. The technical parameters of IGBT absorption varistor are shown in Table 2:

[0105] Table 2

[0106] ;

[0107] The parts not described in detail in this application are all known technologies to those skilled in the art. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not limiting. Although this application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of this application can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of this application, which should be included in the scope of the claims of this application.

Claims

1. A fast switching emergency protection system for aircraft engine testing, characterized in that: include: The fast switching unit is connected to the generator, the rectifier and the emergency protection load circuit respectively, and is used to quickly disconnect the DC load and switch the DC load to the emergency protection load through millisecond-level switching according to the switching instruction issued by the controller; The measuring unit is respectively connected to the turboshaft engine, the generator, the rectifier, and the DC load circuit, and is used to measure the engine gas turbine speed, the free turbine speed, the AC voltage and current, the DC voltage and current, the rectifier fault digital signal, and the DC load system fault digital signal; A controller, connected to the fast switching unit, the measuring unit and the monitoring system circuit respectively, for judging the system fault according to the measurement data collected by the measuring unit and issuing a switching instruction to the fast switching unit accordingly when a fault occurs; A monitoring system, which is in communication with the controller and is used to monitor the parameters and operating status of the rectifier, busbar, and DC load system for parameter display; An emergency protection load is connected to the fast switching unit circuit and is used to provide an emergency protection load when the hybrid power system is in a large state and the load is suddenly lost, so as to prevent the turbine blades from breaking due to overspeeding of the aircraft engine. The emergency protection load includes: an air-cooled AC load, an air-cooled DC load with a rectifier, an air-cooled AC load, an air-cooled DC load with a rectifier, a water-cooled AC load, a water-cooled DC load with a rectifier, an electric dynamometer, an eddy current dynamometer, and a grid-connected load. The emergency protection load is consistent in size with the DC load.

2. A fast switching emergency protection system for aircraft engine testing according to claim 1, characterized in that: The fast switching unit includes a switching switch, which is an IGPT pipe group. The IGPT pipe groups are respectively installed on the DC load circuit and the emergency protection load circuit to form an interlocking relationship.

3. A fast switching emergency protection system for aircraft engine testing according to claim 1, characterized in that: The fast switching unit includes a high-power solid-state relay.

4. A fast switching emergency protection system for aircraft engine testing according to claim 1, characterized in that: The controller adopts a NICRIO controller.

5. A fast switching emergency protection system for aircraft engine testing according to claim 1, characterized in that: The monitoring system is connected to the controller via LAN communication.

6. A fast switching emergency protection system for aircraft engine testing according to claim 5, characterized in that: The LAN communication includes WIFI, Bluetooth, ZigBee, and lora.

7. A fast switching emergency protection system for aircraft engine testing according to claim 1, characterized in that: The method of judging a fault of the system according to the measurement data collected by the measurement unit and sending a switching instruction to the fast switching unit accordingly when a fault occurs specifically includes the following steps: Acquire measurement data collected by the measurement unit, including gas turbine speed, free turbine speed, AC voltage, and AC current; When the engine is in a set power state above the air idle, if a fault is detected, a switching instruction is immediately sent to the fast switching unit for protection. The set power state is specifically a state of more than 80% of the full power of the engine.

8. A fast switching emergency protection system for aircraft engine testing according to claim 7, characterized in that: When the engine is in a set power state above the air idle, if a fault is detected, a switching command is immediately sent to the fast switching unit for protection, which specifically includes the following steps: Engine status judgment: When the gas turbine speed ≥ A, free turbine speed = B, AC voltage ≥ C, AC current ≥ G, the engine is judged to be in a set power state above the air idle, where A is the minimum set value of the gas turbine speed; B is the set value of the free turbine speed; C is the minimum set value of the generator output AC voltage; G is the minimum set value of the generator output AC current; Fault judgment: If the DC current ≤ H, or the DC voltage ≤ J, or a rectifier fault digital signal is received, or a DC load system fault digital signal is received, it is considered to be a fault, where H is the minimum setting value of the DC current, and J is the minimum setting value of the DC voltage; Send command: immediately send a switching command to the fast switching unit for protection.

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