A start control method of a series aviation hybrid power system considering overspeed protection

Abstract

A kind of start control method of series aviation hybrid power system considering overspeed protection relates to the start control method of aviation power device.Proposed a kind of overspeed protection strategy applied to the start process of series aviation hybrid power system, the mechanical problem of power turbine facing overspeed risk in start process is solved by electrical scheme, and the rated speed of power turbine is used as guide, and the appropriate start resistance value is determined in test.The start control method of series aviation hybrid power system is divided into four steps of turboshaft engine start, control rectifier intervention, engine state promotion and electric propulsion system start, the start process is controlled by time sequence, the component coupling characteristics are decoupled to a certain extent, and the requirements of each index of start process are split into different steps to be realized respectively.The processing of component coupling characteristics is simplified, the requirements of each index of system slow-speed state are quickly met, and the performance of power system and development and design efficiency are improved.

Description

Technical Field

[0001] This invention relates to a starting control method for an aircraft power plant, and more particularly to a starting control method for a series hybrid aviation power system that takes overspeed protection into account. Background Technology

[0002] To meet the demands for efficiency, fuel economy, and environmental friendliness in aviation propulsion, electric propulsion systems have become a crucial development direction for the future aviation industry. Compared to all-electric propulsion systems, hybrid power systems are currently receiving increasing attention due to their advantages in range and payload capacity. Similar to new energy vehicles, aviation hybrid power systems include three configurations: series, parallel, and series-parallel. Parallel or series-parallel systems require relatively few modifications to traditional structures and layouts, and may have certain advantages in efficiency. However, series systems achieve complete decoupling of the engine and propeller, allowing for optimized aerodynamic design of the aircraft, thereby reducing overall energy consumption during flight. Series hybrid power systems are expected to become the mainstream propulsion solution for urban commuter, general aviation, and regional jet aircraft in the future.

[0003] For series hybrid power systems, countries in Europe and America, in conjunction with the conceptual designs of future wide-body passenger aircraft N3-X, single-aisle large aircraft STARC-ABL, and regional jet E-Fan X, have conducted ground test research, forming several mature test platforms such as HEIST and NEAT. Domestically, the integration and verification work on series hybrid power systems mainly includes 80kW-level flight demonstration verification and 200kW-level ground test verification (Mei Qing, Jin Hailiang, Shen Yubing. Design and test of aviation oil-electric hybrid power system [J]. Aviation Power, 2021, 30(01): 39-42). With the development of verification technology and the improvement of power level, the experimental research on series aviation hybrid power will gradually carry out the optimization design of test systems, processes, methods, etc. As the basis for various working states of the power plant, the control strategy of the starting process is a key technology in the design of the power plant and its controller. Unlike traditional power systems, series hybrid power systems have many control components and strong coupling characteristics. Currently, there is no publicly available literature that puts forward clear requirements and definitions for their starting process. Therefore, it is particularly necessary to propose a practical starting control method for series hybrid power systems in aviation. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing research on the starting process of series hybrid power systems by providing a starting control method for series hybrid power systems that considers overspeed protection.

[0005] This invention is based on the starting process of a traditional aircraft power plant. First, an overspeed protection device is installed on the generator. By adjusting different starting resistance values, the turbine speed is brought close to the rated speed. Further, after determining the target load resistance value, the starting process of the series-type aircraft hybrid power system is controlled with a defined sequence of steps. Therefore, the starting control method for a series-type aircraft hybrid power system considering overspeed protection can be understood as follows: Based on the rated speed of the turbine and the rated voltage of the DC power grid, and combined with an appropriate overspeed protection strategy for the starting process, a multi-step, time-sequential starting control method is rationally planned.

[0006] This invention includes the following steps:

[0007] 1) Parameter setting method for overspeed protection:

[0008] 1.1) Design of overspeed protection strategy: Connect an adjustable resistive load in parallel between the generator and the main circuit as an overspeed protection device. Since the generator has no additional load during the start-up phase, the power dissipation through resistance can increase the equivalent rotational inertia of the power turbine, thereby increasing the rotor torque and avoiding the risk of overspeed.

[0009] 1.2) Setting the initial starting resistor value: Based on the inverse relationship between the power consumption of the resistor and the resistance value, it is recommended to set the initial value of the adjustable resistive load to a smaller value, so as to avoid the risk of overspeed to a greater extent.

[0010] 1.3) Start the turboshaft engine: Send a start command to the turboshaft engine ECU control unit to bring the turboshaft engine to its own idle state. If the power turbine speed deviates from the rated speed at this time, proceed to the next step.

[0011] 1.4) Setting the starting resistor parameters: Appropriately increase or decrease the starting resistor value to bring the power turbine speed close to the rated speed, and record the target load resistance value as the basis for the design of subsequent starting control methods. The target starting resistor can meet the overspeed protection requirements, avoid unnecessary power loss, and simplify the starting control method to a certain extent.

[0012] 2) Starting control method based on tuning parameters:

[0013] 2.1) Turboshaft engine start-up: This step is the start-up process of a conventional aviation power plant and is the basis for the start-up process of a series aviation hybrid power system.

[0014] 2.2) Controlled rectification intervention: The generator state is adjusted from uncontrolled rectification to controlled rectification, and the output voltage of the generator system is gradually increased by an appropriate increment, so that the DC microgrid voltage is continuously raised to the rated voltage level.

[0015] 2.3) Engine status improvement: Since the intervention of control rectification will cause the power turbine speed to drop, it is necessary to gradually increase the throttle ratio of the turboshaft engine with an appropriate increase so that the power turbine speed can be continuously increased to the rated speed.

[0016] 2.4) Electric Propulsion System Start-up: It is relatively safe to start the electric propulsion system when the power grid is at its rated voltage level and the power turbine is operating at its rated speed. If the electric propulsion system operates stably under minimum conditions at this time, the start-up process of the series hybrid aviation system is considered complete.

[0017] Compared with the prior art, the outstanding advantages of the technical solution of this invention are:

[0018] This invention provides a starting control method for a series hybrid power system considering overspeed protection. This method allows for a clear and convenient start-up process of the series hybrid power system while avoiding the risk of overspeed during startup. On one hand, this invention comprehensively considers the potential overspeed risks during startup as the basis for the starting control method. On the other hand, this invention clearly defines four steps in the starting control method, simplifying the handling of component coupling characteristics and quickly meeting the various performance requirements of the system at idle, greatly improving the performance of the power system and the efficiency of research and development. Attached Figure Description

[0019] Figure 1 The flowchart shows the parameter tuning method considering overspeed protection provided by this invention.

[0020] Figure 2 The flowchart of the starting control method based on tuning parameters provided by the present invention is shown.

[0021] Figure 3 This is a schematic diagram of the application objects in an embodiment of the present invention.

[0022] Figure 4 The figure shows the application results of the parameter tuning method considering overspeed protection in an embodiment of the present invention.

[0023] Figure 5 The diagram shows the application results of the starting control method based on tuning parameters according to an embodiment of the present invention. Detailed Implementation

[0024] To make the design objectives, technical solutions, and engineering advantages of the embodiments of the present invention clearer and more understandable, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are one embodiment of the present invention, and not all embodiments.

[0025] The embodiments of the present invention include the following steps:

[0026] 1) Consider the parameter setting method for overspeed protection, the flowchart is as follows: Figure 1 As shown:

[0027] 1.1) Design of overspeed protection strategy: Connect an adjustable resistive load in parallel between the generator and the main circuit as an overspeed protection device; since the generator has no additional load during the start-up phase, the equivalent rotational inertia of the power turbine can be increased by the power dissipation of the resistor, thereby increasing the rotor torque and avoiding the risk of overspeed.

[0028] 1.2) Setting the initial starting resistor value: Based on the inverse relationship between the power consumption of the resistor and the resistance value, it is recommended to set the initial value of the adjustable resistive load to a smaller value, so as to avoid the risk of overspeed to a greater extent.

[0029] 1.3) Start the turboshaft engine: Send a start command to the turboshaft engine ECU control unit to bring the turboshaft engine to its own idle state, observe the power turbine speed, and determine whether the power turbine speed is close to the rated speed. If the power turbine speed deviates from the rated speed, proceed to the next step.

[0030] 1.4) Setting the starting resistor parameters: Appropriately increase or decrease the starting resistor value to bring the power turbine speed close to the rated speed. Specifically: if the power turbine speed is less than the rated speed, increase the starting resistor value appropriately to bring the power turbine speed close to the rated speed; if the power turbine speed is greater than the rated speed, decrease the starting resistor value appropriately to bring the power turbine speed close to the rated speed. Determine the value of the starting resistor and record the target load resistance value as the basis for the design of the subsequent starting control method. The target starting resistor should meet the overspeed protection requirements, avoid unnecessary power loss, and simplify the starting control method to a certain extent.

[0031] 2) Starting control method based on tuning parameters, flowchart as follows: Figure 2 As shown:

[0032] 2.1) Turboshaft engine start-up: This step is the start-up process of a conventional aviation power plant and is the basis for the start-up process of a series aviation hybrid power system. Start the turboshaft engine to idle state.

[0033] 2.2) Controlled rectification intervention: The generator state is adjusted from uncontrolled rectification to controlled rectification, and the generator system output voltage is gradually increased by an appropriate increment, so that the DC microgrid voltage is continuously increased to the rated voltage level;

[0034] 2.3) Engine status improvement: Since the intervention of control rectification will cause the power turbine speed to drop, it is necessary to gradually increase the throttle ratio of the turboshaft engine with an appropriate increase so that the power turbine speed can be continuously increased to the rated speed.

[0035] 2.4) Start-up of electric propulsion system: It is safer to start the electric propulsion system when the power grid is at the rated voltage level and the power turbine is operating at the rated speed. At this time, if the electric propulsion system is operating stably in the minimum state, the start-up process of the series aero-hybrid power system is considered to be over.

[0036] The following embodiments use a series hybrid power system as an example, specifically including a turboshaft engine, a generator, an overspeed protection resistor, and an electric propulsion system, such as... Figure 3 As shown.

[0037] The specific embodiments of the present invention include the following steps:

[0038] 1) Parameter setting method for overspeed protection:

[0039] 1.1) Design of overspeed protection strategy: Connect an adjustable resistive load in parallel between the generator and the main circuit as an overspeed protection device. A relatively suitable option is to set a DC circuit breaker for the overspeed protection circuit, so that the starting resistor has the ability to be disconnected from the circuit. The purpose is to avoid unnecessary power loss when the rated speed of the power turbine is high.

[0040] 1.2) Set the initial starting resistor value: such as Figure 4 As shown, based on the inverse relationship between the power consumption of the resistor and the resistance value, the maximum power that the initial starting resistor can consume is approximately 10kW.

[0041] 1.3) Start the turboshaft engine to idle and observe the power turbine speed: Send a start command to the turboshaft engine ECU control unit to bring the turboshaft engine to its own idle state and observe whether the power turbine speed is close to the rated speed. At this time, the power turbine speed is about 7000 r / min, which is far from the rated speed. Proceed to the next step.

[0042] 1.4) Setting the starting resistor parameters: Gradually increase the starting resistor value and decrease the starting resistor power consumption. When the starting resistor is cut off, the power turbine speed just meets the rated speed of 10500 r / min, indicating that the application object of this embodiment does not need to consider the overspeed protection strategy.

[0043] 2) Starting control method based on tuning parameters:

[0044] 2.1) Turboshaft engine start-up: After step 1) is completed, if the turboshaft engine is still in idle state, it can directly proceed to step 2.2); during the start-up process of the same hybrid power system, step 1) can be skipped, and step 2) can be executed immediately, starting from step 2.1) using the start-up control method provided by this invention. Figure 5As shown, the initial time t0 is when the turboshaft engine ECU control unit issues the start command. From time t1, the power turbine starts to drive the generator to generate electricity, and at time t2, the turboshaft engine reaches its own idle state.

[0045] 2.2) Controlled rectification intervention: At time t3, the generator state is adjusted from uncontrolled rectification to controlled rectification, and the DC microgrid is raised to the rated voltage level in the order of "400V-540V".

[0046] 2.3) Engine status improvement: In step 2.2), the power turbine speed decreases. Starting from time t4, the throttle ratio of the turboshaft engine is gradually increased by 1% to bring the power turbine speed back up to the rated speed.

[0047] 2.4) Electric propulsion system startup: The electric propulsion system is started at its minimum state at time t5. At this time, all components maintain stable operation, and the power turbine speed does not fluctuate significantly. It can be considered that the series aero-hydroelectric system has started successfully.

[0048] This invention first proposes an overspeed protection strategy for the starting process of a series aero-hybrid power system. The mechanical problem of overspeed risk to the power turbine during startup is addressed by an electrical solution, and a suitable starting resistance value is determined experimentally, guided by the rated speed of the power turbine. Based on this, the starting control method for the series aero-hybrid power system is divided into four steps: turboshaft engine starting, control rectification intervention, engine status enhancement, and electric propulsion system startup. The starting process is controlled sequentially, decoupling the coupling characteristics of components to a certain extent. The various performance requirements of the starting process are implemented separately in different steps.

[0049] The above embodiments are merely preferred embodiments of the present invention and should not be considered as limiting the scope of the present invention. All equivalent variations and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A starting control method for a series hybrid power system for aviation considering overspeed protection, characterized in that... Includes the following steps: 1) Parameter setting method for overspeed protection: 1.1) Design overspeed protection strategy: Connect an adjustable resistive load in parallel between the generator and the main circuit as an overspeed protection device; 1.2) Set the initial starting resistance value: Set the initial value of the overspeed protection device, i.e., the adjustable resistive load; 1.3) Starting the turboshaft engine: Send a start command to the turboshaft engine ECU control unit to bring the turboshaft engine to its own idle state; 1.4) Set the starting resistor parameters: Increase or decrease the starting resistor value appropriately to make the power turbine speed close to the rated speed, and record the target load resistance value as the basis for the design of subsequent starting control methods; 2) Starting control method based on tuning parameters: 2.1) The specific resistance value of the overspeed protection resistor needs to be determined through step 1); after the target load resistance value is calculated, the specific resistance value is formally set for the test object, and then the following steps begin; 2.2) Turboshaft engine start-up: This step is the start-up process of a conventional aero-engine and is the basis for the start-up process of a series aero-electric hybrid power system; 2.3) Controlled rectification intervention: The generator state is adjusted from uncontrolled rectification to controlled rectification, so that the DC microgrid voltage is raised to the rated voltage level; 2.4) Engine status improvement: Since the intervention of control rectification will cause the power turbine speed to drop, increase the throttle ratio of the turboshaft engine to restore the power turbine speed to the rated speed; 2.5) Start-up of electric propulsion system: When the power grid is at its rated voltage level and the power turbine is operating at its rated speed, the electric propulsion system is started at its minimum state.

Images