Engine grid-connected control method

Abstract

The invention discloses an engine grid-connected control method, and relates to generator grid connection, which comprises the following steps of: starting a timing period after entering a PTO (Power Take Off) mode, clearing an adjusted step length after the timing period is ended, restoring the adjusted step length to an initial step length, and restoring the rotating speed of an engine to a droop rotating speed at the same time. Potential instability caused by step length adjustment of the system is avoided, the overall efficiency of the system is improved, consistency and interpretability of data can be kept, and subsequent analysis and optimization are facilitated.

Description

Technical Field

[0001] The present invention relates to a generator grid connection, and more particularly to a generator grid connection control method. Background Art

[0002] When the generator is used in the supporting power generation field, it is sometimes necessary to make electrical connections with adjacent power systems for power exchange, that is, grid connection. Traditional grid connection requires stable power exchange through a power distributor, and is only applicable to modes where the engine speed can be adjusted through an instrument. It is not applicable to modes where the engine speed needs to be manually adjusted, such as PTO. However, there are also DCUs that can control the stable droop of the speed. Without passing through a power distributor, the target speed is corrected according to a filter coefficient to prevent the torque percentage, that is, the ratio of the current output oil volume to the external characteristic limit oil volume from jumping, thereby achieving stable control of the speed and power and completing grid connection. In PTO mode, the speed is adjusted up / down through the PTO button to automatically distribute the load. Exit droop control after the droop prohibition switch is closed. However, in this process, the control data of the PTO often interferes with subsequent control. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an engine grid-connected control method in view of the deficiencies in the prior art, thereby solving the problem that the control data of the PTO may interfere with subsequent control.

[0004] The present invention discloses an engine grid-connected control method, which is as follows: after entering the PTO mode, a timing cycle is started, and when the timing cycle ends, the adjusted step length is cleared to restore it to the initial step length, and the engine speed is restored to the drooping speed.

[0005] Preferably, the start time of the timing cycle is:

[0006] After the grid-connected switch is pressed, the timing cycle is started, and the engine involved in the grid connection begins to distribute power according to the PTO mode. At the same time, it is determined whether the engine speed is stable and whether the power distribution meets the preset target. If so, the grid connection is completed and the grid connection control is exited.

[0007] Preferably, during the engine grid-connected process, if the droop prohibition switch is closed, the droop control is exited and the rotation speed is restored to the rotation speed before the PTO grid-connected.

[0008] Preferably, the rotation speed of the PTO before being connected to the grid is the idle speed of the engine.

[0009] Preferably, the timing period is 15-35s.

[0010] Preferably, after the engine is connected to the grid, the delay timing is started, and after the delay timing ends, the adjusted step length is cleared again.

[0011] Preferably, the delay timing is 25-40s.

[0012] Preferably, during the PTO mode grid-connected process, the step adjustment record and the grid-connected time during the PTO mode process are obtained, the step adjustment mean is calculated based on the step adjustment record, and then a new adjustment step is obtained by evaluating the grid-connected time and the step adjustment mean; and the adjustment step is used as a reference step for subsequent grid-connected processes.

[0013] Preferably, the relationship between the grid-connected time and a preset time threshold is determined. If the grid-connected time is greater than the time threshold, the initial step size is increased within the step size adjustment mean range so that the grid-connected time is less than or equal to a target multiple of the timing cycle.

[0014] Beneficial Effects

[0015] The advantages of the present invention are that by setting a time limit, the original step size can be restored after the step size adjustment, thereby avoiding potential instability of the system caused by the step size adjustment. In addition, the dynamic clearing of the step size can also reduce unnecessary resource consumption and improve the overall efficiency of the system, and clearing the temporarily adjusted step size helps to maintain the consistency and interpretability of the data, which is convenient for subsequent analysis and optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flow chart of the engine grid-connected control method of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the embodiments, but it does not constitute any limitation to the present invention. Any limited number of modifications made by anyone within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0018] See also Figure 1 , an engine grid-connected control method of the present invention comprises the following steps:

[0019] In the first step, after the grid-connected switch (i.e., PTO enable switch) is pressed, the engine speed increases to the initial speed, and a timing cycle is started at the same time. In this embodiment, the timing cycle is selected as 20s. In no-load or light-load mode, adjust the PTO+ and PTO- buttons to adjust the speed increase / decrease, activate the droop mode, and the grid-connected engine begins to distribute power.

[0020] The second step is to determine whether the engine speed is stable and whether the power distribution meets the preset target. If so, the grid connection is completed and the grid connection control is exited. Otherwise, the PTO mode continues to be executed.

[0021] Step 3: When the timing cycle ends, clear the adjusted step length to restore it to the initial step length, and restore the engine speed to the droop speed. Setting the time to clear the adjusted step length can be achieved through reasonable time limits and effective technology, which can ensure stable system operation, optimize resource usage, and simplify data analysis, ensuring that the adjusted step length does not cause system instability, thereby avoiding the problem of system instability after clearing the step length.

[0022] Step 4: Determine whether the droop inhibit switch is closed. If the droop inhibit switch is closed, exit the droop control, and the speed is restored to the speed before the PTO is connected to the grid, that is, idle speed, and the grid connection is terminated; otherwise, reset the timing cycle and repeat the second step.

[0023] In this embodiment, after the engine is connected to the grid, a delay timer is started, specifically 30 seconds, and after the delay timer ends, the adjusted step length is cleared again to ensure that the control parameters generated in the PTO mode are completely cleared and restored to the initial step length. Generally speaking, the initial step length is 2r / min, and the initial speed of the engine in the PTO mode is 1500r / min.

[0024] During the PTO mode grid connection process, the step adjustment record and grid connection time in the PTO mode process are obtained, the step adjustment mean is calculated according to the step adjustment record, and then a new adjustment step is obtained according to the grid connection time and the step adjustment mean; and the adjustment step is used as a reference step for the subsequent grid connection process. Recording the step adjustment process and evaluating it to make adjustments can provide a more effective reference for the subsequent adjustment process, which can greatly improve the grid connection time of the PTO mode in the grid connection.

[0025] The specific evaluation process is to determine the relationship between the grid-connected time and the preset time threshold. If the grid-connected time is greater than the time threshold, the initial step size is increased within the step adjustment mean range so that the grid-connected time is less than or equal to the target multiple of the timing cycle, and the increased initial step size is used as the reference step size.

[0026] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A method for controlling an engine in grid connection, characterized in that: The method comprises the following steps: after entering the PTO mode, starting a timing cycle, clearing the adjusted step length when the timing cycle ends, restoring the step length to the initial step length, and restoring the engine speed to the drooping speed.

2. The engine grid-connected control method according to claim 1, characterized in that: The start time of the timing cycle is: After the grid-connected switch is pressed, the timing cycle is started, and the engine involved in the grid connection begins to distribute power according to the PTO mode. At the same time, it is determined whether the engine speed is stable and whether the power distribution meets the preset target. If so, the grid connection is completed and the grid connection control is exited.

3. The engine grid-connected control method according to claim 1, characterized in that: During the engine grid connection process, if the droop prohibition switch is closed, the droop control is exited and the speed is restored to the speed before the PTO grid connection.

4. The engine grid-connected control method according to claim 3, characterized in that: The rotation speed of the PTO before being connected to the grid is the idle speed of the engine.

5. The engine grid-connected control method according to claim 1, characterized in that: The timing period is 15-35s.

6. The engine grid-connected control method according to claim 1, characterized in that: After the engine is connected to the grid, the delay timing is started, and after the delay timing ends, the adjusted step length is cleared again.

7. The engine grid-connected control method according to claim 6, characterized in that: The delay timing is 25-40s.

8. The engine grid-connected control method according to claim 1, characterized in that: During the PTO mode grid-connected process, the step adjustment record and the grid-connected time during the PTO mode process are obtained, the step adjustment mean is calculated according to the step adjustment record, and then a new adjustment step is obtained by evaluating the grid-connected time and the step adjustment mean; and the adjustment step is used as a reference step for subsequent grid-connected processes.

9. The engine grid-connected control method according to claim 8, characterized in that: The relationship between the grid-connected time and a preset time threshold is determined. If the grid-connected time is greater than the time threshold, the initial step size is increased within the step size adjustment mean range so that the grid-connected time is less than or equal to a target multiple of the timing cycle.

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