Control method for suppressing feedforward disturbance by using interpolation table look-up method

Abstract

The invention provides a control method for suppressing feed-forward disturbance by using an interpolation look-up table method, and the method introduces an intelligent judgment system, combines a unit three-dimensional interpolation feed-forward function, and dynamically confirms stable output of interpolation feed-forward by setting a frequency difference change fluctuation value # imgabs0 #. And when the variable quantity of the frequency difference value is not greater than # imgabs 1 #, the feed-forward value is kept unchanged, and when the variable quantity of the frequency difference value is greater than # imgabs 2 #, the feed-forward value is updated. According to the method, the original adjusting speed is guaranteed, meanwhile, random fluctuation of the feed-forward three-dimensional interpolation caused by fluctuation of the frequency difference value is avoided, the stability of unit load adjusting is improved, and the method is suitable for the field of water-turbine generator set control.

Description

Technical Field

[0001] The present invention relates to the technical field of hydropower unit control, and in particular to a control method for suppressing feedforward disturbances using an interpolation table lookup method. The method is suitable for scenarios where feedforward interpolation instability occurs due to frequency fluctuations during load regulation of a hydropower generator set. Background Art

[0002] To address the issue of inaccurate power response characteristics due to fluctuations in unit head during hydropower unit operation, existing technologies have introduced a feedforward function with adaptive control characteristics into turbine control. This function uses theoretical three-dimensional curves of the turbine's head, opening, and power as feedforward. While this method effectively mitigates the impact of unit head variations on the unit's power response characteristics, real-time changes in frequency difference during actual regulation can cause fluctuations in the interpolated output, impacting the stability of the unit's regulation and ultimately negatively impacting the stable operation of the power grid. Summary of the Invention

[0003] The purpose of the present invention is to provide a control method for suppressing the use of interpolation table lookup method as feedforward disturbance, so as to solve the problem that during the load regulation process of hydropower units, the unstable frequency difference affects the stability of the interpolation output, thereby affecting the stable operation of the power grid.

[0004] In order to achieve the above technical features, the purpose of the present invention is achieved as follows: a control method for suppressing feedforward disturbances using an interpolation table lookup method comprises the following steps: Construct theoretical three-dimensional curve functions of turbine head, opening and power; In the frequency regulation mode, the difference between the given frequency and the frequency feedback is calculated, and the difference is processed with dead zone, the adjustment coefficient is calculated and the amplitude is limited to generate a frequency regulation load instruction; Superimpose the primary frequency modulation load instruction with the original load instruction to obtain a new power instruction; The new power command is divided into two paths. One path is directly input into the three-dimensional interpolation table and acts on the actuator command. The other path is input into the power PID input and is summed with the previous path after PID adjustment and acts on the actuator command. Introducing frequency difference fluctuation value , when the frequency difference change is not greater than When the frequency difference is greater than When the frequency modulation feedforward value is updated once, the guide vane opening and blade opening corresponding to the new frequency difference are obtained.

[0005] Preferably, the constructed three-dimensional curve function of the turbine is: ; Where, is the hydraulic power of the turbine unit, is the working water head of the turbine, is the guide vane opening, is the blade opening.

[0006] Preferably, the calculation method of the primary frequency modulation load instruction is: ; Where, is a primary frequency regulation load, is the frequency modulation coefficient, is the rated load of the unit, is the frequency difference, is the rated speed.

[0007] Preferably, the novel control system with three-dimensional interpolation feedforward function includes two modes: power mode and frequency mode; In the frequency regulation mode, the difference between the given frequency and the frequency feedback passes through the frequency dead zone, the adjustment coefficient, and the limit link to form a frequency regulation load instruction. This instruction is superimposed on the original load instruction to obtain a new power instruction.

[0008] Preferably, when the frequency difference variation No more than When the primary frequency feedforward maintains the previous guide vane opening and blade opening constant; When the frequency difference changes Greater than When the frequency modulation feedforward is and Update to new frequency difference Corresponding guide vane opening and blade opening .

[0009] Preferably, a frequency modulation is defined as: ; Where, is the speed inappropriate rate, is the speed interpolation, is the rated speed; Primary frequency modulation coefficient: ; Where, is the frequency modulation coefficient; Primary frequency regulation load: ; Where, is the primary frequency regulation load of the unit, is the rated load of the unit; Unit load instruction: ; Where, is the load instruction after a frequency modulation action, This is the load instruction before the frequency modulation starts; Guide vane opening instruction after one frequency modulation action: ; Where, It is the guide vane opening instruction corresponding to the load after a frequency modulation action.

[0010] Preferably, another aspect of the present invention provides a control system for suppressing the use of an interpolation lookup table method as a feedforward disturbance, characterized in that the control system is used to implement the control method for suppressing the use of an interpolation lookup table method as a feedforward disturbance, characterized in that it includes: Frequency difference calculation module: calculates the difference between the given frequency and the frequency feedback; Frequency dead zone processing module: performs dead zone processing on the frequency difference to filter out small fluctuations; Adjustment coefficient and amplitude limiting module: applies adjustment coefficient and performs amplitude limiting to generate a frequency regulation load instruction; Load instruction superposition module: superimposes the primary frequency modulation load instruction with the original load instruction to generate a new power instruction; Three-dimensional interpolation table module: generates actuator instructions through a three-dimensional interpolation table based on new power instruction parameters; PID adjustment module: performs PID adjustment on another power command; Instruction summing module: sums the instructions output by the three-dimensional interpolation table and the instructions after PID adjustment, and acts on the actuator; Intelligent judgment module: judge whether the frequency difference change is greater than the set fluctuation value , decides whether to update the feedforward value.

[0011] The present invention has the following beneficial effects: 1. While retaining the original advantages of the feedforward function, such as rapidity and water head adaptability, the present invention enhances the stability of the feedforward interpolation output control signal caused by frequency difference fluctuations.

[0012] 2. Change the fluctuation value by introducing frequency difference As a basis for judgment, it avoids the frequent changes of the feedforward value with the frequency difference, and effectively improves the stability of the hydropower unit during load regulation.

[0013] 3. It ensures the original regulation speed of the hydropower unit and improves the stability of the power grid operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will be further described below with reference to the accompanying drawings and examples.

[0015] Figure 1 It is the overall flow chart of the present invention. DETAILED DESCRIPTION

[0016] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0017] Example 1: A control method for suppressing feedforward disturbances using an interpolation lookup table method comprises the following steps: Construct theoretical three-dimensional curve functions of turbine head, opening and power; In the frequency regulation mode, the difference between the given frequency and the frequency feedback is calculated, and the difference is processed with dead zone, the adjustment coefficient is calculated and the amplitude is limited to generate a frequency regulation load instruction; Superimpose the primary frequency modulation load instruction with the original load instruction to obtain a new power instruction; The new power command is divided into two paths. One path is directly input into the three-dimensional interpolation table and acts on the actuator command. The other path is input into the power PID input and is summed with the previous path after PID adjustment and acts on the actuator command. Introducing frequency difference fluctuation value , when the frequency difference change is not greater than When the frequency difference is greater than When the frequency modulation feedforward value is updated once, the guide vane opening and blade opening corresponding to the new frequency difference are obtained.

[0018] Preferably, the constructed three-dimensional curve function of the turbine is: ; Where, is the hydraulic power of the turbine unit, is the working water head of the turbine, is the guide vane opening, is the blade opening.

[0019] Preferably, the calculation method of the primary frequency modulation load instruction is: ; Where, is a primary frequency regulation load, is the frequency modulation coefficient, is the rated load of the unit, is the frequency difference, is the rated speed.

[0020] Preferably, the novel control system with three-dimensional interpolation feedforward function includes two modes: power mode and frequency mode; In the frequency regulation mode, the difference between the given frequency and the frequency feedback passes through the frequency dead zone, the adjustment coefficient, and the limit link to form a frequency regulation load instruction. This instruction is superimposed on the original load instruction to obtain a new power instruction.

[0021] Preferably, when the frequency difference variation No more than When the primary frequency feedforward maintains the previous guide vane opening and blade opening constant; When the frequency difference changes Greater than When the frequency modulation feedforward is and Update to new frequency difference Corresponding guide vane opening and blade opening .

[0022] Preferably, a frequency modulation is defined as: ; Where, is the speed inappropriate rate, is the speed interpolation, is the rated speed; Primary frequency modulation coefficient: ; Where, is the frequency modulation coefficient; Primary frequency regulation load: ; Where, is the primary frequency regulation load of the unit, is the rated load of the unit; Unit load instruction: ; Where, is the load instruction after a frequency modulation action, This is the load instruction before the frequency modulation starts; Guide vane opening instruction after one frequency modulation action: ; Where, It is the guide vane opening instruction corresponding to the load after a frequency modulation action.

[0023] Example 2: Another aspect of the present invention provides a control system for suppressing feedforward disturbances using an interpolation lookup table method, wherein the control system is used to implement the control method for suppressing feedforward disturbances using an interpolation lookup table method, and comprises: Frequency difference calculation module: calculates the difference between the given frequency and the frequency feedback; Frequency dead zone processing module: performs dead zone processing on the frequency difference to filter out small fluctuations; Adjustment coefficient and amplitude limiting module: applies adjustment coefficient and performs amplitude limiting to generate a frequency regulation load instruction; Load instruction superposition module: superimposes the primary frequency modulation load instruction with the original load instruction to generate a new power instruction; Three-dimensional interpolation table module: generates actuator instructions through a three-dimensional interpolation table based on new power instruction parameters; PID adjustment module: performs PID adjustment on another power command; Instruction summing module: sums the instructions output by the three-dimensional interpolation table and the instructions after PID adjustment, and acts on the actuator; Intelligent judgment module: judge whether the frequency difference change is greater than the set fluctuation value , decides whether to update the feedforward value.

[0024] Example 3: Taking a certain type of hydro-generator set as an example, the control method of the present invention is specifically implemented in the following steps: 1. Parameter settings: Set the frequency difference fluctuation value .

[0025] Turbine rated speed , rated load .

[0026] Adjustment coefficient .

[0027] 2. Load adjustment process: When the grid frequency changes, the system detects the difference between the frequency setting and the frequency feedback. .

[0028] like ,because (Right now ), a frequency feedforward maintains the current guide vane opening and blade opening It avoids frequent changes of the feedforward value caused by small frequency fluctuations and ensures the stability of the regulation process.

[0029] If the grid frequency fluctuates greatly, ,at this time (Right now ), the system is based on the new frequency difference , calculate the new guide vane opening through the turbine three-dimensional curve function and blade opening , update the frequency modulation feedforward value once, so that the unit can adapt to larger frequency changes, while ensuring that the update of the feedforward value will not be too frequent.

[0030] 3. Instruction generation and execution: The frequency difference passes through the frequency dead zone and the adjustment coefficient After the limit link, a frequency regulation load instruction is generated .

[0031] Original load instruction , the new power instruction after superposition .

[0032] One command inputs a three-dimensional interpolation table, according to the water head , new power command 401MW and blade opening , check the guide vane opening instruction , acting on the actuator.

[0033] Another command input is the power PID input, and after PID adjustment, it is summed with the previous command and acts on the actuator together to achieve precise adjustment of the unit load.

[0034] Experimental verification: By conducting experiments on this hydro-generator set and comparing the unit operating data before and after adopting the control method of the present invention, the results are as follows: When the present invention is not used: When the frequency fluctuation range is During the load regulation process of the unit, the feedforward interpolation output fluctuation amplitude reaches , resulting in large fluctuations in unit load and affecting the stability of the power grid.

[0035] After adopting the present invention: under the same frequency fluctuation conditions, the feedforward interpolation output fluctuation amplitude is controlled within Within 2000 s, the load regulation stability of the units is significantly improved, and the operation of the power grid is more stable.

[0036] Experimental results show that the present invention can effectively suppress the instability problem of feedforward interpolation caused by frequency difference fluctuation, thereby improving the stability of load regulation of hydropower units and the reliability of power grid operation.

[0037] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A control method for suppressing feedforward disturbances using an interpolation lookup table method, characterized in that: include: Construct theoretical three-dimensional curve functions of turbine head, opening and power; In the frequency regulation mode, the difference between the given frequency and the frequency feedback is calculated, and the difference is processed with dead zone, the adjustment coefficient is calculated and the amplitude is limited to generate a frequency regulation load instruction; Superimpose the primary frequency modulation load instruction with the original load instruction to obtain a new power instruction; The new power command is divided into two paths. One path is directly input into the three-dimensional interpolation table and acts on the actuator command. The other path is input into the power PID input and is summed with the previous path after PID adjustment and acts on the actuator command. Introducing frequency difference fluctuation value , when the frequency difference change is not greater than When , the primary frequency modulation feedforward value remains unchanged; When the frequency difference is greater than When the frequency modulation feedforward value is updated once, the guide vane opening and blade opening corresponding to the new frequency difference are obtained.

2. The control method for suppressing feedforward disturbances by using an interpolation table lookup method according to claim 1, characterized in that: The constructed three-dimensional curve function of the turbine is: ； Where, is the hydraulic power of the turbine unit, is the working water head of the turbine, is the guide vane opening, is the blade opening.

3. The control method for suppressing feedforward disturbance by using an interpolation table lookup method according to claim 1, characterized in that: The calculation method of the primary frequency modulation load instruction is: ； Where, is a primary frequency regulation load, is the frequency modulation coefficient, is the rated load of the unit, is the frequency difference, is the rated speed.

4. The control method for suppressing feedforward disturbances by using an interpolation table lookup method according to claim 3, characterized in that: The new control system with three-dimensional interpolation feedforward function includes two modes: power mode and frequency mode; In the frequency regulation mode, the difference between the given frequency and the frequency feedback passes through the frequency dead zone, the adjustment coefficient, and the limit link to form a frequency regulation load instruction. This instruction is superimposed on the original load instruction to obtain a new power instruction.

5. A control method for suppressing feedforward disturbances using an interpolation table lookup method according to claim 4, characterized in that: When the frequency difference changes No more than When the primary frequency feedforward maintains the previous guide vane opening and blade opening constant; When the frequency difference changes Greater than When the frequency modulation feedforward is and Update to new frequency difference Corresponding guide vane opening and blade opening .

6. A control method for suppressing feedforward disturbances using an interpolation table lookup method according to claim 5, characterized in that: Primary frequency modulation definition: ； Where, is the speed inappropriate rate, is the speed interpolation, is the rated speed; Primary frequency modulation coefficient: ； Where, is the frequency modulation coefficient; Primary frequency regulation load: ； Where, is the primary frequency regulation load of the unit, is the rated load of the unit; Unit load instruction: ； Where, is the load instruction after a frequency modulation action, This is the load instruction before the frequency modulation starts; Guide vane opening instruction after one frequency modulation action: ； Where, It is the guide vane opening instruction corresponding to the load after a frequency modulation action.

7. A control system for suppressing disturbances using an interpolation lookup table method as a feedforward, characterized in that: The control system is used to implement a control method for suppressing feedforward disturbances using an interpolation table lookup method as described in any one of claims 1 to 6, and is characterized by comprising: Frequency difference calculation module: calculates the difference between the given frequency and the frequency feedback; Frequency dead zone processing module: performs dead zone processing on the frequency difference to filter out small fluctuations; Adjustment coefficient and amplitude limiting module: applies adjustment coefficient and performs amplitude limiting to generate a frequency regulation load instruction; Load instruction superposition module: superimposes the primary frequency modulation load instruction with the original load instruction to generate a new power instruction; Three-dimensional interpolation table module: generates actuator instructions through a three-dimensional interpolation table based on new power instruction parameters; PID adjustment module: performs PID adjustment on another power command; Instruction summing module: sums the instructions output by the three-dimensional interpolation table and the instructions after PID adjustment, and acts on the actuator; Intelligent judgment module: judge whether the frequency difference change is greater than the set fluctuation value , decides whether to update the feedforward value.

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