Method and device for compensating the gap between the servomotor and the guide vanes of a hydraulic turbine

Abstract

The present application belongs to the technical field of hydroelectric unit control, and particularly relates to a water turbine servomotor and guide vane gap compensation method and device. The method comprises: obtaining gap boundary parameters and transmission parameters between a water turbine servomotor and guide vane; establishing a gap hysteresis model according to the gap boundary parameters, the gap hysteresis model being used to describe a nonlinear mapping relationship between servomotor displacement and guide vane opening; inverting the gap hysteresis model to obtain a corresponding gap hysteresis inverse model; and compensating for a gap dead zone between the servomotor and guide vane based on the gap hysteresis inverse model. The method improves the response speed of the guide vane opening, the active power regulation accuracy under small frequency difference disturbance, and the qualified rate of the integral contribution rate of the first frequency modulation under small disturbance.

Description

Technical Field

[0001] This invention belongs to the field of hydropower unit control technology, specifically relating to a method and device for compensating the gap between a turbine servo and a guide vane. Background Technology

[0002] With the large-scale integration of new energy power generation equipment into the power grid, especially photovoltaic and wind power generation equipment with large output fluctuations and weak inertial support capabilities, the stability of the power grid faces severe challenges. The demand for energy storage equipment for frequency regulation, phase regulation, peak shaving and valley filling has increased dramatically. As an important energy storage power generation device, hydroelectric generator sets have the advantages of stable operation and fast frequency regulation response. Their proportion in the new power system is increasing, and their primary frequency regulation performance and accuracy directly affect the frequency stability of the power grid.

[0003] The current power grid has established strict assessment standards for the primary frequency regulation performance of hydropower units. Among them, the primary frequency regulation integral power contribution rate is an important assessment indicator. However, in actual operation, hydropower units generally have problems such as response lag, insufficient active power output, and easy reverse regulation, which leads to a low pass rate of the primary frequency regulation integral power contribution rate under small frequency difference disturbances, thus failing to meet the assessment requirements.

[0004] Studies have shown that the main reason for the above problems is the presence of multiple dead zones in the turbine speed control system. Figure 1 The control block diagram of the turbine speed regulation system is as follows: Figure 1 As shown, existing research mainly focuses on the dead zone of PID control and the dead zone of the relay itself. These two types of dead zones cause delays in the transmission of control signals, resulting in a lag in the primary frequency regulation action. However, in actual unit experiments, when the frequency difference crosses these two types of dead zones, the relay operates but the guide vane opening does not change, as shown in the example. Figure 2 As shown, this problem stems from the gap dead zone caused by the physical gap between the relay and the guide vane. Existing research often overlooks the existence of this dead zone, resulting in insufficient active power response during primary frequency regulation under small frequency difference disturbances.

[0005] Therefore, hydro turbines urgently need a low-cost electro-hydraulic transmission system gap compensation technology that requires no complex modifications and is easy to implement in engineering, in order to compensate for the nonlinear transmission gap dead zone between the servo and the guide vane, improve the response speed of the primary frequency regulation of the hydro turbine unit under small frequency difference disturbances and the accuracy of active power regulation, thereby optimizing the qualification rate of integral power contribution rate. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention provides a method and device for compensating the gap between the turbine servo and the guide vane, which solves the problem that the servo moves but the guide vane does not move after the frequency difference crosses the conventional dead zone.

[0007] A first aspect of this invention provides a method for compensating the clearance between a turbine servo and guide vanes, comprising: Obtain the clearance boundary parameters and transmission parameters between the turbine servo and the guide vanes; A gap hysteresis model is established based on the gap boundary parameters. The gap hysteresis model is used to describe the nonlinear mapping relationship between the relay displacement and the guide vane opening. Inverting the gap hysteresis model yields the corresponding inverse gap hysteresis model; The gap dead zone between the relay and the guide vane is compensated based on the gap hysteresis inverse model.

[0008] Preferably, obtaining the clearance boundary parameters and transmission parameters between the turbine servo and the guide vanes includes: Design a small frequency difference upper boundary disturbance experiment to identify the positive boundary of the gap, the maximum positive displacement of the relay and the upper boundary transmission ratio; Design a small frequency difference lower boundary disturbance experiment to identify the gap reverse boundary, the maximum reverse displacement of the relay and the lower boundary transmission ratio; The average of the upper boundary transmission ratio and the lower boundary transmission ratio is determined as the transmission ratio between the relay and the guide vane.

[0009] Preferably, the design of the small frequency difference upper boundary disturbance experiment identifies the positive boundary of the gap, the maximum positive displacement of the relay, and the upper boundary transmission ratio, including: Stabilize the unit frequency at the initial frequency of the upper disturbance, and initiate frequency disturbance upwards according to a preset step size until the guide vane opening changes. The displacement change of the relay at this time is determined as the positive boundary of the gap. Continue to initiate frequency disturbances upwards according to the preset step size until the unit frequency reaches the upper disturbance termination frequency. Record the change in guide vane opening during this period, and determine the displacement of the relay corresponding to the maximum opening among the changes in guide vane opening as the maximum positive displacement of the relay. The ratio of the change in guide vane opening to the change in relay displacement is determined as the upper boundary transmission ratio.

[0010] Preferably, the design of the small frequency difference lower boundary disturbance experiment identifies the gap reverse boundary, the maximum reverse displacement of the relay, and the lower boundary transmission ratio, including: Stabilize the unit frequency at the initial frequency of the lower disturbance, and initiate a frequency disturbance downward according to a preset step size until the guide vane opening changes. The displacement change of the relay at this time is determined as the gap reverse boundary. Continue to initiate frequency disturbance downwards according to the preset step size until the unit frequency reaches the lower disturbance termination frequency. Record the change in guide vane opening during this period, and determine the displacement of the relay corresponding to the maximum opening among the changes in guide vane opening as the maximum reverse displacement of the relay. The ratio of the change in guide vane opening to the change in relay displacement is determined as the lower boundary transmission ratio.

[0011] Preferably, establishing the gap hysteresis model based on the gap boundary parameters includes: The gap hysteresis model can be expressed as the following mathematical expression: ; Where x(t) is the displacement of the relay at time t, y(t) is the opening of the guide vane at time t, k is the transmission ratio between the relay and the guide vane, b1 is the clearance reverse boundary, and b2 is the clearance positive boundary.

[0012] Preferably, the step of inverting the gap hysteresis model to obtain the corresponding inverse gap hysteresis model includes: Inverting the mathematical expression of the gap hysteresis model yields the mathematical expression of the inverse gap hysteresis model as follows: ; Where y(n) is the output command value of the PID controller in the turbine speed regulation system at time n, x(n) is the displacement command value output to the servo motor by the gap hysteresis inverse model at time n, and x(n-1) is the displacement command value output to the servo motor by the gap hysteresis inverse model at the previous time.

[0013] Preferably, the compensation for the dead zone between the relay and the guide vane based on the inverse gap hysteresis model includes: The gap hysteresis inverse model is input into the output loop of the PID controller in the turbine speed regulation system. A compensation amount is generated based on the output command value of the PID controller. The compensation amount is then superimposed on the output command value and sent into the execution loop of the relay. When the output command value is within the dead zone boundary, the gap hysteresis inverse model exits in a step manner, the compensation amount is zero, and the dead zone boundary is formed by the opposite of the gap reverse boundary and the gap positive boundary. When the output command value exceeds the dead zone boundary and the rate of change of the output command value is positive, the gap hysteresis inverse model is applied in a slope manner, and the compensation amount is taken from the positive boundary of the gap. When the output command value exceeds the dead zone boundary and the rate of change of the output command value is negative, the gap hysteresis inverse model is applied in a slope manner, and the compensation amount is the opposite of the gap reverse boundary. When the rate of change of the output command value is zero, the gap hysteresis inverse model exits in a step manner.

[0014] Preferably, after compensating for the dead zone of the gap between the relay and the guide vane based on the gap hysteresis inverse model, the method further includes: Design a small frequency difference disturbance experiment to collect the operating data of the turbine speed regulation system under the operation of the gap hysteresis inverse model. The operating data includes unit power, frequency difference, inverse compensation increment, primary frequency regulation action status and guide vane opening. Calculate the theoretical integral power, actual integral power, and integral power contribution rate corresponding to a single frequency regulation based on the aforementioned operating data. The integral power contribution rate is compared with a preset power grid assessment threshold to quantitatively evaluate the compensation effect of the gap hysteresis inverse model on the gap dead zone.

[0015] Preferably, the step of calculating the theoretical integral power, actual integral power, and integral power contribution rate corresponding to a single frequency regulation based on the operating data includes: The theoretical integral charge H is calculated according to the following formula. e : ; Where t0 is the time when the unit frequency exceeds the primary frequency regulation dead zone, t1 is the time when the unit frequency returns to the primary frequency regulation dead zone, Δf(t) is the value of the grid frequency exceeding the artificial frequency regulation dead zone at time t, and f n b is the rated frequency of the power grid. p The constant slip coefficient is MCR, and the rated active power output of the unit is MCR. The actual integral energy H is calculated according to the following formula. i : ; Among them, P t P0 represents the actual active power generated by the unit at time t, and P0 is the average value of the actual active power generated by the unit within a preset time period before time t0. The integral energy contribution rate K is calculated according to the following formula: .

[0016] A second aspect of the present invention provides a turbine servo and guide vane clearance compensation device, the device comprising: The parameter acquisition module is configured to acquire the clearance boundary parameters and transmission parameters between the turbine servo and the guide vanes. The model building module is configured to build a gap hysteresis model based on the gap boundary parameters. The gap hysteresis model is used to describe the nonlinear mapping relationship between the relay displacement and the guide vane opening. The model inversion module is configured to invert the gap hysteresis model to obtain the corresponding gap hysteresis inverse model. The dead zone compensation module is configured to compensate for the dead zone between the relay and the guide vane based on the gap hysteresis inverse model.

[0017] The beneficial effects of this invention include: By first identifying the gap boundary, then establishing a hysteresis model, and finally performing inverse compensation, this complete chain transforms the long-neglected physical gap dead zone between the relay and the guide vane into an object that can be precisely compensated by the algorithm. Compared to existing methods that only focus on the PID control dead zone and the relay's stationary dead zone, this solution fundamentally solves the problem of the relay moving while the guide vane remains stationary even after the frequency difference crosses the conventional dead zone. It significantly improves the response speed of the guide vane opening under small frequency difference disturbances, the accuracy of active power regulation, and the pass rate of the integral power contribution rate under small frequency difference disturbances. Furthermore, the entire compensation process is integrated in software, requiring no high-precision mechanical parts or complex hardware modifications, offering significant advantages in terms of low cost and ease of engineering implementation. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a control block diagram of a conventional water turbine speed regulation system shown in an embodiment of the present invention; Figure 2 This refers to the gap dead zone caused by the physical gap between the relay and the guide vane, as shown in the embodiment of the present invention. Figure 3 This is a flowchart illustrating a method for compensating the clearance between a turbine servo and guide vanes, as shown in an embodiment of the present invention. Figure 4 This is a flowchart illustrating step S1 in an embodiment of the present invention; Figure 5 This is a flowchart illustrating step S101 in an embodiment of the present invention; Figure 6 This is a flowchart illustrating step S102 in an embodiment of the present invention; Figure 7 This is a schematic diagram of the gap hysteresis model shown in an embodiment of the present invention; Figure 8 A flowchart illustrating step S4 in an embodiment of the present invention; Figure 9This is a control block diagram illustrating the application of gap hysteresis inverse model compensation to the turbine speed control system in an embodiment of the present invention. Figure 10 The following is a logic block diagram of the enable function shown in an embodiment of the present invention; Figure 11 This is a graph showing the changing trends of various parameters in an embodiment of the present invention; Figure 12 This is a structural block diagram of a turbine relay and guide vane clearance compensation device according to an embodiment of the present invention. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] The following will clearly and completely describe the concept, specific structure, and technical effects of the present invention in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Furthermore, all connections / linkages involved in the patent do not simply refer to direct contact between components, but rather to the ability to form a better connection structure by adding or reducing connecting accessories according to specific implementation conditions. The various technical features in this invention can be combined interactively without contradicting each other.

[0022] like Figure 3 As shown in the figure, an embodiment of the present invention provides a method for compensating the clearance between a turbine servo and guide vanes, comprising: S1. Obtain the clearance boundary parameters and transmission parameters between the turbine servo and the guide vanes.

[0023] Among them, obtaining the clearance boundary parameters and transmission parameters between the turbine servo and the guide vane refers to determining, through actual measurement, how much displacement the servo needs to travel in both the forward and reverse directions to actually drive the guide vane to change its opening. The amount of displacement that the servo travels but does not cause the guide vane to move is the clearance, and the critical values ​​of the clearance in both directions are the clearance boundary parameters.

[0024] The relay receives displacement commands from the speed control system and drives the linkage mechanism to pull the guide vanes. The opening of the guide vanes directly determines the active power of the unit. Because the relay and the guide vanes are connected by mechanical linkages, there is a physical gap in the pin hole fit of the linkages. Therefore, the relay will not immediately drive the guide vanes when it starts to move. The guide vanes will only start to move after the relay displacement crosses this physical gap. This gap is manifested as a dead zone in control.

[0025] S2. Establish a gap hysteresis model based on the gap boundary parameters. The gap hysteresis model is used to describe the nonlinear mapping relationship between the relay displacement and the guide vane opening.

[0026] The so-called nonlinear mapping relationship refers to the fact that the displacement of the relay and the opening of the guide vane are not a simple proportional linear relationship, but there is a dead zone interval. Within this interval, the opening of the guide vane remains unchanged when the displacement of the relay changes. Only after crossing the dead zone does the opening of the guide vane change proportionally with the displacement of the relay. Furthermore, the inflection points of entering and exiting the dead zone are different when the relay moves forward and backward, thus forming a hysteresis loop similar to a parallelogram on the relationship curve between displacement and opening.

[0027] S3. Invert the gap hysteresis model to obtain the corresponding gap hysteresis inverse model.

[0028] The gap hysteresis model describes how the displacement of the relay is mapped to the guide vane opening, while the inverse model describes how much displacement command should be issued to the relay in order to obtain the desired guide vane opening.

[0029] S4. Compensate for the dead zone between the actuator and the guide vane based on the gap hysteresis inverse model.

[0030] The core idea of ​​dead zone compensation is to use algorithmic lead to offset mechanical lag. The magnitude and direction of the compensation are determined by whether the current command crosses the dead zone boundary and the direction of the command change. In this scheme, the compensation link is connected only in parallel via software, requiring no hardware modification to the unit. It can be put into operation simply by substituting the measured gap boundary parameters into the inverse model expression, thereby significantly improving the response sensitivity of the guide vane opening and the accuracy of active power regulation under small frequency difference disturbances.

[0031] This solution transforms the long-neglected physical gap dead zone between the relay and guide vanes into an object that can be precisely canceled by the algorithm through a complete chain of first identifying the gap boundary, then establishing a hysteresis model, and finally performing inverse compensation. Compared to existing methods that only focus on the PID control dead zone and the relay's stationary dead zone, this solution fundamentally solves the problem of the relay moving while the guide vanes remain stationary even after the frequency difference crosses the conventional dead zone, significantly improving the response speed of the guide vane opening and the accuracy of active power regulation under small frequency difference disturbances. Furthermore, the entire compensation process is connected in parallel via software, requiring no high-precision mechanical parts or complex hardware modifications, offering significant advantages in terms of low cost and ease of engineering implementation.

[0032] In some embodiments, such as Figure 4 As shown, the clearance boundary parameters and transmission parameters between the turbine servo and the guide vanes are obtained, including: S101. Design a small frequency difference upper boundary disturbance experiment to identify the positive boundary of the gap, the maximum positive displacement of the relay, and the upper boundary transmission ratio.

[0033] For the relay's forward movement, a series of slowly increasing frequency disturbance tests are arranged. By observing when the guide vane opening begins to change and the magnitude of the change, the clearance boundary and transmission ratio in the forward direction can be deduced. Small frequency difference refers to a very small applied frequency disturbance amplitude, typically less than 0.08Hz. This is because the power grid assessment focuses on the primary frequency regulation performance under small frequency difference conditions, and the gap dead zone has the most significant impact under these conditions. Upper boundary disturbance specifically refers to a disturbance where the frequency changes above the rated value. In this case, the relay moves in the forward direction. The forward boundary is the displacement traversed by the relay from the start of forward movement to the first forward movement of the guide vane. The upper boundary transmission ratio reflects the proportional relationship between the guide vane opening and the relay displacement after crossing the dead zone.

[0034] In some embodiments, such as Figure 5 As shown, step S101 includes: S1011. Stabilize the unit frequency at the initial frequency of the upper disturbance, initiate frequency disturbance upward according to the preset step size, until the guide vane opening changes, and determine the displacement change of the servo at this time as the positive boundary of the gap. S1012. Continue to initiate frequency disturbance upwards according to the preset step size until the unit frequency reaches the upper disturbance termination frequency. Record the change in guide vane opening during this period, and determine the servo displacement corresponding to the maximum opening among the change in guide vane opening as the maximum positive displacement of the servo. S1013. The ratio of the change in guide vane opening to the change in relay displacement is determined as the upper boundary transmission ratio.

[0035] Specifically, under low-load, non-compensation operating conditions of a 120MW unit with rated power, the permanent slip rate b p =0.04, at this time the PID control dead zone range is ±0.05Hz, and the relay dead zone range is ±0.003Hz.

[0036] The unit frequency was stabilized at the initial disturbance frequency of 50.053Hz. Frequency disturbances were initiated incrementally upwards in steps of 0.001Hz. When the guide vane opening first changed, the change in relay displacement Δx (approximately 2.33mm) was recorded as the positive boundary b2. It is worth noting that the above boundary parameters only apply to the 120MW rated power unit mentioned in this embodiment; specific parameters may vary for different units. Subsequently, the disturbance was continued upwards in steps of 0.001Hz until the unit frequency reached the termination disturbance frequency of 50.06Hz. During this period, the change in guide vane opening Δy was continuously recorded. G The maximum positive displacement a2 is taken as approximately 0.35% of the servo displacement corresponding to the maximum opening. Finally, the upper boundary transmission ratio k1 = Δy is obtained by dividing the change in the guide vane opening of this section by the corresponding change in the servo displacement.G / △x.

[0037] S102. Design a small frequency difference lower boundary disturbance experiment to identify the gap reverse boundary, the maximum reverse displacement of the relay, and the lower boundary transmission ratio.

[0038] For the condition where the relay moves in the opposite direction, a set of slowly decreasing frequency disturbance tests is arranged, which are opposite in direction to the upper boundary test but in the same principle. The lower boundary disturbance specifically refers to the disturbance where the frequency changes in a direction lower than the rated value. At this time, the relay moves in the opposite direction. The reverse boundary is the displacement traversed by the relay from the start of the reverse movement to the first reverse action of the guide vane. The maximum reverse displacement of the relay is the maximum displacement reached in this direction. The lower boundary transmission ratio reflects the proportional relationship between the guide vane opening and the relay displacement after crossing the dead zone in the reverse direction.

[0039] In some embodiments, such as Figure 6 As shown, S102 includes: S1021. Stabilize the unit frequency at the lower disturbance starting frequency, initiate frequency disturbance downward according to the preset step size, until the guide vane opening changes, and determine the displacement change of the servo at this time as the gap reverse boundary. S1022. Continue to initiate frequency disturbance downwards according to the preset step size until the unit frequency reaches the lower disturbance termination frequency. Record the change in guide vane opening during this period, and determine the servo displacement corresponding to the maximum opening among the change in guide vane opening as the maximum reverse displacement of the servo. S1023. The ratio of the change in guide vane opening to the change in relay displacement is determined as the lower boundary transmission ratio.

[0040] Specifically, under low-load, non-compensation operating conditions of a 120MW unit with rated power, the unit frequency is stabilized at 49.947Hz, the initial disturbance frequency. Frequency disturbances are initiated progressively downwards in steps of 0.001Hz. When the guide vane opening first changes, the displacement change Δx of the relay is recorded as approximately 2mm, serving as the reverse boundary b1. Subsequently, the disturbance is continued downwards in steps of 0.001Hz until the unit frequency reaches the termination frequency of the disturbance. During this period, the change in guide vane opening Δy is continuously recorded. G The maximum reverse displacement a1 is taken as approximately 0.3% of the servo displacement corresponding to the maximum opening. Finally, the lower boundary transmission ratio k2 is obtained by dividing the change in the guide vane opening of this section by the corresponding change in the servo displacement.

[0041] S103. The average value of the upper boundary transmission ratio and the lower boundary transmission ratio is determined as the transmission ratio between the relay and the guide vane.

[0042] This scheme, through the design of two sets of small-frequency difference disturbance experiments at the upper and lower boundaries, comprehensively identifies the boundaries b2 and b1 of the gap hysteresis loop in both positive and negative directions, as well as the maximum displacements a2 and a1. By taking the average of the transmission ratio k = (k1 + k2) / 2, unidirectional measurement errors are eliminated. Compared with direct estimation or unidirectional identification, the obtained parameters are more comprehensive and accurate, providing a reliable parameter basis for subsequent establishment of the gap hysteresis model and inverse compensation. Moreover, the experiment can be completed simply by reading frequency and displacement opening data in the speed control system, without the need for additional sensors or hardware modifications, making it simple to operate and low in cost.

[0043] In some embodiments, such as Figure 7 As shown, a gap hysteresis model is established based on the gap boundary parameters, including: The gap hysteresis model can be expressed as the following mathematical expression: (1); Where x(t) is the displacement of the relay at time t, y(t) is the opening of the guide vane at time t, k is the transmission ratio between the relay and the guide vane, b1 is the clearance reverse boundary, and b2 is the clearance positive boundary.

[0044] Specifically, by substituting the measured values ​​of the positive boundary b2 (approximately 2.33 mm), the negative boundary b1 (approximately 2 mm), and the uniform transmission ratio k (approximately 0.15) from the previous stage into the piecewise expression, the specific hysteresis relationship between the displacement of the 120MW unit's relay and the guide vane opening is obtained. When the unit frequency is affected by high-frequency grid disturbances, causing the relay to undergo positive displacement, the guide vane opening remains unchanged as long as the displacement has not exceeded b2. Once the displacement exceeds b2, the guide vane opening increases linearly by 0.15 with the excess amount. When the frequency changes to low-frequency disturbances, causing the relay to undergo reverse displacement, the guide vane opening remains unchanged as long as the reverse displacement has not exceeded b1. After exceeding b1, the guide vane opening decreases linearly. When the relay stops moving, the guide vane opening is locked at the value of the previous moment. Thus, the directional hysteresis characteristics of the physical gap at the control level are fully reproduced using a set of clear mathematical rules.

[0045] The hysteresis relationship can be described using a piecewise function that switches between the forward and reverse segments and the dead zone holding segment, based on the sign of the relay displacement x(t). Alternatively, the forward boundary b2 and the reverse boundary b1 can be embedded in the expression as segment inflection points to accurately locate the two ends of the dead zone platform. The guide vane opening within the dead zone can be handled by maintaining the output at the previous time step y(t-1) when x(t) is equal to zero. Alternatively, the transmission ratio k can be used as a unified slope for both forward and reverse segments to ensure the parallelism of the two inclined sides of the loop.

[0046] This scheme uses a concise piecewise mathematical expression to fully characterize the directional nonlinear hysteresis relationship between the relay displacement and the guide vane opening. It includes both the dead zone platform defined by the positive boundary b2 and the negative boundary b1, and the two parallel inclined sides determined by the uniform transmission ratio k. Compared to approximations using only a single proportional relationship, this expression accurately reflects the asymmetric turning characteristics of the gap dead zone in both directions, laying a precise mathematical foundation for subsequent inversion of the model and construction of compensation. Furthermore, the expression is clear in form and the physical meaning of the parameters is explicit, facilitating understanding by engineers and direct substitution with measured parameters.

[0047] In some embodiments, the gap hysteresis model is inverted to obtain the corresponding inverse gap hysteresis model, including: Inverting the mathematical expression of the gap hysteresis model yields the mathematical expression of the inverse gap hysteresis model, as follows: (2); Where y(n) is the output command value of the PID controller in the turbine speed regulation system at time n, x(n) is the displacement command value output to the servo motor by the gap hysteresis inverse model at time n, and x(n-1) is the displacement command value output to the servo motor by the gap hysteresis inverse model at the previous time.

[0048] Specifically, by substituting the measured positive boundary b2 (approximately 2.33 mm), negative boundary b1 (approximately 2 mm), and uniform transmission ratio k (approximately 0.15) of this 120MW unit into the inverse model expression, a compensation calculation rule that can be directly put into operation is obtained. When the PID controller outputs a positive command v(t) due to high-frequency grid disturbances, the inverse model divides this command by 0.15 to convert it into the nominal displacement of the relay and adds an extra 2.33 mm, so that the relay quickly completes the positive gap and drives the guide vanes to operate at the desired opening. When the PID controller outputs a negative command due to low-frequency disturbances, the inverse model subtracts an extra 2 mm after converting the command to make up for the negative gap. When the PID output command is zero, the inverse model keeps the displacement command of the previous moment unchanged, thus achieving advance compensation for the gap without causing a sudden jump in the command.

[0049] The inverse model can be constructed by taking the inverse function of each piecewise expression of the original hysteresis model and converting the gap boundary from the subtracted term to the additional term. Alternatively, the sign of the PID output command v(t) can be used as a criterion to switch between the positive compensation segment, the negative compensation segment, and the holding segment. The continuity of commands at the dead zone can be handled by maintaining the state of the previous displacement command u(t-1) when v(t) is equal to zero. Alternatively, the reciprocal of the transmission ratio k can be used as a unified conversion factor for both the positive and negative segments to ensure consistency in the compensation rules for both segments.

[0050] This solution derives a structurally symmetrical inverse model expression by progressively inverting the gap hysteresis model, thus compensating for the displacement that would otherwise be swallowed by mechanical backlash at the command end. Compared to directly issuing PID commands without compensation, the inverse model enables the relay to quickly cross the dead zone defined by the positive boundary b2 and the negative boundary b1, significantly shortening the response lag of the guide vane opening. Moreover, the inverse model maintains the command from the previous moment at the dead zone, ensuring continuous and smooth commands and avoiding shocks during compensation switching. The expression consists only of measured parameters, eliminating the need for online identification of complex parameters and facilitating direct deployment in engineering projects.

[0051] In some embodiments, such as Figure 8 As shown, compensation for the dead zone between the actuator and the guide vane is performed based on the inverse model of gap hysteresis, including: S401. Input the gap hysteresis inverse model into the output circuit of the PID controller in the turbine speed regulation system, generate the compensation amount according to the output command value of the PID controller, and then send the compensation amount to the output command value and send it into the execution circuit of the relay.

[0052] After applying the gap hysteresis inverse model to the turbine speed control system, its overall control block diagram is obtained as follows: Figure 9 As shown, the logic block diagram of the enable function is as follows: Figure 10 As shown.

[0053] Substituting the parameters from formula (1) into formula (2), we can obtain the compensation amount: (3); The PID controller is the core regulator in the speed control system, calculating the control quantity based on the frequency difference. Its output loop is the channel through which the control command is transmitted to the actuator. Connecting the inverse model to this loop means that the compensation action occurs before the command actually drives the relay, thus enabling the cancellation of the impending gap in advance. The purpose of superimposing the compensation quantity is to ensure that the command actually received by the relay includes the additional displacement for crossing the physical gap, allowing the guide vanes to follow the PID command action in a timely manner.

[0054] S402. When the output command value is within the dead zone boundary, the gap hysteresis inverse model exits in a step manner, the compensation amount is zero, and the dead zone boundary is formed by the opposite of the gap reverse boundary and the gap positive boundary. S403. When the output command value exceeds the dead zone boundary and the rate of change of the output command value is positive and the transmission ratio k=1, the gap hysteresis inverse model is activated in the slope manner, and the compensation is taken at the positive boundary of the gap. S404. When the output command value exceeds the dead zone boundary and the rate of change of the output command value is negative and the transmission ratio k=1, the backlash hysteresis inverse model is activated in a slope manner, and the compensation amount is the opposite of the backlash reverse boundary. S405. When the rate of change of the output command value is zero, the gap hysteresis inverse model exits in a step manner.

[0055] Specifically, on this 120MW unit, after integrating the gap hysteresis inverse model into the PID controller output loop, taking a small-frequency disturbance as an example, after the disturbance begins, the frequency rises and enters the gap dead zone. The PID output command value crosses the positive dead zone boundary and the rate of change is positive. The inverse compensation increment is applied in a slope manner, and the guide vane opening decreases from 56.9% to 56.3%, with the unit power gradually decreasing from 120MW to 119MW. When the frequency crosses the gap dead zone, the PID command rate of change returns to zero, and the inverse compensation increment exits in a step manner, with the guide vane opening returning to the initial value of 56.9% and the unit power returning to the initial value. Throughout the process, the compensation amount automatically switches between zero, b2, and -b1 based on whether the command crosses the dead zone boundary formed by -b1 to b2, and the sign of the command rate of change, achieving precise on-demand compensation for the gap dead zone.

[0056] The input and output of the compensation amount can be controlled by using an enable logic that determines whether the PID output command value exceeds the dead zone boundary, or by using the positive, negative, or zero states of the command change rate to determine whether the compensation amount is b2, -b1, or zero. The smoothness of the compensation process can be ensured by smoothly inputting the compensation amount according to the slope after exceeding the boundary, or by quickly exiting the compensation amount using a step method within the dead zone and when the command change rate is zero, thus balancing smooth input and timely exit.

[0057] This solution integrates the gap hysteresis inverse model into the PID output loop and automatically switches the compensation amount based on whether the command crosses the dead zone boundary formed by -b1 and b2, and the positive or negative zero state of the command's rate of change. This achieves a refined control logic where forward motion compensates for b2, reverse motion compensates for -b1, and compensation is zeroed when stationary or in the dead zone. Compared to fixed compensation or no compensation, this solution can improve response speed by promptly crossing the gap during relay movement, and avoids jitter and bias caused by ineffective compensation when stationary or in the dead zone. This logic significantly improves the response sensitivity of the guide vane opening and the accuracy of active power regulation under small frequency difference disturbances, and all logic is implemented in software without requiring hardware modification.

[0058] In some embodiments, after compensating for the dead zone of the gap between the actuator and the guide vane based on the inverse model of gap hysteresis, the method further includes: S5. Design a small frequency difference disturbance experiment to collect the operating data of the turbine speed regulation system under the operation of the gap hysteresis inverse model. The operating data includes unit power, frequency difference, inverse compensation increment, primary frequency regulation action status and guide vane opening. S6. Calculate the theoretical integral power, actual integral power, and integral power contribution rate corresponding to a single frequency regulation based on the operating data. S7. Compare the integral power contribution rate with the preset power grid assessment threshold to quantitatively evaluate the compensation effect of the gap hysteresis inverse model on the gap dead zone.

[0059] Specifically, after applying the gap hysteresis inverse model for compensation on this 120MW unit, the permanent slip coefficient b is designed. p For the small frequency difference up-disturbance and down-disturbance experiment with a value of 0.04, after stabilizing the unit frequency at 50.053Hz, an up-disturbance of 0.001Hz was introduced to 50.055Hz and then returned to 50.053Hz. The experiment was repeated multiple times to avoid randomness. During the process, operating data such as the unit power frequency difference inverse compensation increment primary frequency regulation status and guide vane opening were continuously collected. The changing trends of each parameter are as follows: Figure 11 As shown, after the disturbance begins, the frequency rises into the gap dead zone. At this time, the reverse compensation increment is put into operation with a slope of -0.5%. The primary frequency regulation operates normally, and the guide vane opening changes from 56.9% to 56.3%. The unit power also changes with the guide vane opening, gradually decreasing from 120MW to 119MW. When the frequency crosses the gap dead zone, the reverse compensation increment is put into operation in a step, the primary frequency regulation does not operate, the guide vane opening returns to the initial value of 56.9%, and the unit power also returns to the initial value of 119MW.

[0060] The acquisition of operational data can be achieved by repeatedly conducting small-frequency-difference upward and downward disturbance experiments under compensation conditions, while simultaneously recording multiple parameters such as power frequency difference and guide vane opening. Alternatively, the operation interval can be distinguished by using the 0 and 1 flags of the primary frequency regulation operation status to accurately capture the integration period. The quantification of the compensation effect can be achieved by first calculating the theoretical and actual integrated power and then determining the contribution rate. Alternatively, the contribution rate can be directly compared with the grid assessment threshold of 0.35, supplemented by multiple repeated experiments and averaging to ensure the reliability of the evaluation conclusions.

[0061] This scheme elevates the compensation effect from a qualitative judgment based solely on waveform observation to a quantitative assessment based on grid performance indicators by re-collecting operational data under compensation conditions, calculating the theoretical integrated power, actual integrated power, and integrated power contribution rate, and then comparing these with the grid assessment threshold. Compared to existing practices lacking quantitative methods, this scheme objectively demonstrates that the compensation stage's elimination of gap dead zones indeed significantly increases the contribution rate beyond the 0.35 qualification threshold. Furthermore, repeated experiments eliminate randomness, providing direct and convincing engineering verification evidence for the effectiveness of the compensation algorithm.

[0062] In some embodiments, the calculation of the theoretical integral energy, actual integral energy, and integral energy contribution rate corresponding to a single frequency regulation based on operating data includes: The theoretical integral charge H is calculated according to the following formula. e : (4) Where t0 is the time when the unit frequency exceeds the primary frequency regulation dead zone, t1 is the time when the unit frequency returns to the primary frequency regulation dead zone, Δf(t) is the value of the grid frequency exceeding the artificial frequency regulation dead zone at time t, and f n b is the rated frequency of the power grid. p The constant slip coefficient is MCR, and the rated active power output of the unit is MCR. The actual integral charge H is calculated using the following formula. i : (5); Among them, P t P0 represents the actual active power generated by the unit at time t, and P0 is the average value of the actual active power generated by the unit within a preset time period before time t0. The integral energy contribution rate K is calculated according to the following formula: (6); Specifically, the permanent slip coefficient b of this 120MW unit p In the small frequency difference disturbance experiment with a value of 0.04, the time frequency difference and unit power were first read from the original data table. The start time t0 and end time t1 of the disturbance were determined by iterating through the data, resulting in a disturbance duration of approximately 29.383 seconds. The average power of approximately 119.4762 MW in the 5 seconds prior to time t0 was then taken as the reference power P0. Finally, the theoretical integrated power H was calculated. e The calculation formula yields H e Approximately -9.5623 MW·s, based on actual integrated energy H i The calculation formula yields H i Approximately -11.1056 MW·s, finally expressed as H i Divide by H e The integral energy contribution rate K is approximately 116.11%. Figure 11 As shown, the result is much higher than the 0.35 qualified threshold specified for the power grid under small frequency difference disturbance, which quantitatively proves the significant optimization effect of the compensation algorithm on the primary frequency regulation performance.

[0063] Among them, the theoretical integral charge H e The calculation can be performed by converting the frequency difference Δf(t) into a power increment based on the static droop characteristic of primary frequency regulation and then integrating it during the action period. Alternatively, the integration period can be ensured to be consistent with the primary frequency regulation action range by precisely defining the upper and lower limits of integration using t0 and t1. The actual integrated power H... i The calculation can be performed using the actual power P t The method of integrating the difference between the power and the reference power P0 over the same time period can also be used to eliminate the interference of steady-state power fluctuations on the integration results by taking the average power of the 5 seconds before time t0 as the reference power P0.

[0064] This scheme calculates the theoretical integral charge H according to the prescribed formula. e and actual integrated power consumption H i The ratio of the two is then used to obtain the integral power contribution rate K, establishing the evaluation of primary frequency regulation performance on a rigorous mathematical integral basis. Compared to the rough judgment based solely on observing the power waveform, this method can provide a quantitative result that is completely consistent with the power grid assessment criteria. The measured contribution rate K is approximately 116.11%, far exceeding the qualified threshold of 0.35. This method not only objectively proves the significant improvement of the integral power contribution rate of primary frequency regulation by gap compensation, but also provides a repeatable and comparable quantitative basis for the engineering verification of the compensation effect.

[0065] like Figure 12 As shown in the embodiment of this application, a turbine servo and guide vane clearance compensation device 50 is provided. The device includes: The parameter acquisition module 501 is configured to acquire the clearance boundary parameters and transmission parameters between the turbine servo and the guide vane. The model building module 502 is configured to build a gap hysteresis model based on the gap boundary parameters. The gap hysteresis model is used to describe the nonlinear mapping relationship between the relay displacement and the guide vane opening. The model inversion module 503 is configured to invert the gap hysteresis model to obtain the corresponding gap hysteresis inverse model. The dead zone compensation module 504 is configured to compensate for the dead zone between the actuator and the guide vane based on the inverse model of gap hysteresis.

[0066] It should be noted that the turbine servo and guide vane clearance compensation device provided in the above embodiments is only illustrated by the division of the above functional modules when performing clearance compensation. In actual applications, the above functions can be assigned to different functional modules as needed. That is, the internal structure of the turbine servo and guide vane clearance compensation device will be divided into different functional modules to complete all or part of the functions described above.

[0067] Furthermore, the embodiments of the turbine servo and guide vane clearance compensation device and the turbine servo and guide vane clearance compensation method provided in the above embodiments belong to the same concept. The specific way in which each module performs its operation has been described in detail in the method embodiments, and will not be repeated here.

[0068] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of the present invention.

Claims

1. A method for compensating the clearance between a turbine servo and guide vanes, characterized in that, include: Obtain the clearance boundary parameters and transmission parameters between the turbine servo and the guide vanes; A gap hysteresis model is established based on the gap boundary parameters. The gap hysteresis model is used to describe the nonlinear mapping relationship between the relay displacement and the guide vane opening. Inverting the gap hysteresis model yields the corresponding inverse gap hysteresis model; The gap dead zone between the relay and the guide vane is compensated based on the gap hysteresis inverse model.

2. The method for compensating the clearance between a turbine servo and guide vanes according to claim 1, characterized in that, The acquisition of the clearance boundary parameters and transmission parameters between the turbine servo and the guide vanes includes: Design a small frequency difference upper boundary disturbance experiment to identify the positive boundary of the gap, the maximum positive displacement of the relay and the upper boundary transmission ratio; Design a small frequency difference lower boundary disturbance experiment to identify the gap reverse boundary, the maximum reverse displacement of the relay and the lower boundary transmission ratio; The average of the upper boundary transmission ratio and the lower boundary transmission ratio is determined as the transmission ratio between the relay and the guide vane.

3. The method for compensating the clearance between a turbine servo and guide vanes according to claim 2, characterized in that, The design of the small frequency difference upper boundary disturbance experiment identified the positive boundary of the gap, the maximum positive displacement of the relay, and the upper boundary transmission ratio, including: Stabilize the unit frequency at the initial frequency of the upper disturbance, and initiate frequency disturbance upwards according to a preset step size until the guide vane opening changes. The displacement change of the relay at this time is determined as the positive boundary of the gap. Continue to initiate frequency disturbances upwards according to the preset step size until the unit frequency reaches the upper disturbance termination frequency. Record the change in guide vane opening during this period, and determine the displacement of the relay corresponding to the maximum opening among the changes in guide vane opening as the maximum positive displacement of the relay. The ratio of the change in guide vane opening to the change in relay displacement is determined as the upper boundary transmission ratio.

4. The method for compensating the clearance between a turbine servo and guide vanes according to claim 2, characterized in that, The design of the small frequency difference lower boundary disturbance experiment identifies the gap reverse boundary, the maximum reverse displacement of the relay, and the lower boundary transmission ratio, including: Stabilize the unit frequency at the initial frequency of the lower disturbance, and initiate a frequency disturbance downward according to a preset step size until the guide vane opening changes. The displacement change of the relay at this time is determined as the gap reverse boundary. Continue to initiate frequency disturbance downwards according to the preset step size until the unit frequency reaches the lower disturbance termination frequency. Record the change in guide vane opening during this period, and determine the displacement of the relay corresponding to the maximum opening among the changes in guide vane opening as the maximum reverse displacement of the relay. The ratio of the change in guide vane opening to the change in relay displacement is determined as the lower boundary transmission ratio.

5. The method for compensating the clearance between a turbine servo and guide vanes according to claim 1, characterized in that, The step of establishing a gap hysteresis model based on the gap boundary parameters includes: The gap hysteresis model can be expressed as the following mathematical expression: ； Where x(t) is the displacement of the relay at time t, y(t) is the opening of the guide vane at time t, k is the transmission ratio between the relay and the guide vane, b1 is the reverse boundary of the gap, and b2 is the positive boundary of the gap.

6. The method for compensating the clearance between a turbine servo and guide vanes according to claim 5, characterized in that, The step of inverting the gap hysteresis model to obtain the corresponding inverse gap hysteresis model includes: Inverting the mathematical expression of the gap hysteresis model yields the mathematical expression of the inverse gap hysteresis model as follows: ； Where y(n) is the output command value of the PID controller in the turbine speed regulation system at time n, x(n) is the displacement command value output to the relay by the gap hysteresis inverse model at time n, and x(n-1) is the displacement command value output to the relay by the gap hysteresis inverse model at the previous time.

7. The method for compensating the clearance between a turbine servo and guide vanes according to claim 6, characterized in that, The compensation for the dead zone between the relay and the guide vane based on the gap hysteresis inverse model includes: The gap hysteresis inverse model is input into the output loop of the PID controller in the turbine speed regulation system. A compensation amount is generated based on the output command value of the PID controller. The compensation amount is then superimposed on the output command value and sent into the execution loop of the relay. When the output command value is within the dead zone boundary, the gap hysteresis inverse model exits in a step manner, the compensation amount is zero, and the dead zone boundary is formed by the opposite of the gap reverse boundary and the gap positive boundary. When the output command value exceeds the dead zone boundary and the rate of change of the output command value is positive and the transmission ratio k=1, the gap hysteresis inverse model is applied in a slope manner, and the compensation amount is taken from the positive boundary of the gap. When the output command value exceeds the dead zone boundary and the rate of change of the output command value is negative and the transmission ratio k=1, the gap hysteresis inverse model is activated in a slope manner, and the compensation amount is the opposite of the gap reverse boundary. When the rate of change of the output command value is zero, the gap hysteresis inverse model exits in a step manner.

8. The method for compensating the clearance between a turbine servo and guide vanes according to claim 1, characterized in that, After compensating for the dead zone of the gap between the relay and the guide vane based on the gap hysteresis inverse model, the method further includes: Design a small frequency difference disturbance experiment to collect the operating data of the turbine speed regulation system under the operation of the gap hysteresis inverse model. The operating data includes unit power, frequency difference, inverse compensation increment, primary frequency regulation action status and guide vane opening. Calculate the theoretical integral power, actual integral power, and integral power contribution rate corresponding to a single frequency regulation based on the aforementioned operating data. The integral power contribution rate is compared with a preset power grid assessment threshold to quantitatively evaluate the compensation effect of the gap hysteresis inverse model on the gap dead zone.

9. A method for compensating the clearance between a turbine servo and guide vanes according to claim 8, characterized in that, The step of calculating the theoretical integral power, actual integral power, and integral power contribution rate corresponding to a single frequency regulation based on the operational data includes: The theoretical integral charge H is calculated according to the following formula. e : ； Where t0 is the time when the unit frequency exceeds the dead zone of the primary frequency regulation operation, t1 is the time when the unit frequency returns to the dead zone of the primary frequency regulation operation, Δf(t) is the value of the grid frequency exceeding the artificial dead zone of frequency regulation at time t, and f n b is the rated frequency of the power grid. p The constant slip coefficient is MCR, and the rated active power output of the unit is MCR. The actual integral energy H is calculated according to the following formula. i : ； Among them, P t P0 represents the actual active power generated by the unit at time t, and P0 is the average value of the actual active power generated by the unit within a preset time period before time t0. The integral energy contribution rate K is calculated according to the following formula: 。 10. A turbine relay and guide vane clearance compensation device, characterized in that, The device includes: The parameter acquisition module is configured to acquire the clearance boundary parameters and transmission parameters between the turbine servo and the guide vanes. The model building module is configured to build a gap hysteresis model based on the gap boundary parameters. The gap hysteresis model is used to describe the nonlinear mapping relationship between the relay displacement and the guide vane opening. The model inversion module is configured to invert the gap hysteresis model to obtain the corresponding gap hysteresis inverse model. The dead zone compensation module is configured to compensate for the dead zone between the relay and the guide vane based on the gap hysteresis inverse model.

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