Control method and device for adjusting system of hydroelectric generating set

Abstract

The invention provides a control method and device for a hydroelectric generating set adjusting system. The device comprises a hydroelectric generating set nonlinear model; introducing a dynamic integral variable, and constructing an expansion adjustment output function; performing coordinate transformation on the system containing the expansion regulation output function, and establishing a mapping relation between the virtual control quantity and the actual guide vane control input; designing a sliding mode surface based on the chained integral standard form, and constructing a control law including equivalent control and switching control; performance constraints are introduced, and sliding mode surface parameters are obtained through solving; a control law corresponding to the virtual control quantity is inverted to a physical control space through a mapping relation, and a nonlinear robust sliding mode control signal suitable for the hydroelectric generating set adjusting system is obtained; gain-adjustable parallel superposition is carried out on the nonlinear robust sliding mode control signal and a traditional PID control signal, and a final guide vane opening control instruction is generated to execute control operation. The stability of the hydroelectric generating set adjusting system can be improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydroelectric power generation, and particularly relates to a control method and device of a hydroelectric generating unit regulating system. BACKGROUND

[0002] At present, the traditional PID control method is generally used in the speed regulating system of a hydroelectric generating unit. This method is simple in structure and easy to implement, but has obvious shortcomings. The traditional PID controller often ignores the uncertainty factors in the system model, such as parameter perturbation and model linearization error, and cannot effectively cope with various disturbances and nonlinear characteristics in the actual operation condition, resulting in the decline of control performance. With the expansion of the power system scale, the network structure and operation condition are complex and changeable, and the adaptability of the traditional PID controller is insufficient, which cannot effectively meet the high-precision control requirements of frequency stability and power tracking, and may even lead to the decline of the operation stability of the power system. The traditional control strategy often needs the accurate mathematical model of the system, but the actual operation of the hydroelectric generating unit system is often accompanied by parameter uncertainty and external random disturbance, which limits the performance of the traditional PID control method. In order to solve the above problems, in recent years, modern advanced control theories such as sliding mode control, robust control and nonlinear control have been gradually applied to the design of the speed regulating system of the hydroelectric generating unit. Among them, the sliding mode control has the characteristics of fast response and insensitivity to system parameter changes, and the robust control method can effectively resist the influence of model uncertainty and disturbance. However, the use of sliding mode control or robust control alone cannot completely solve the nonlinear and complex working condition problems encountered in the guide vane opening control process of the hydroelectric generating unit.

[0003] Therefore, for the hydroelectric generating unit regulating system, it is urgent to develop a new type of control method with nonlinear characteristics, strong robustness and good anti-interference performance to solve the problems existing in the prior art and further improve the overall performance and stability of the hydroelectric generating unit speed regulating system. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a control method and device of a hydroelectric generating unit regulating system to improve the stability of the hydroelectric generating unit regulating system.

[0005] In a first aspect, the present application provides a control method of a hydroelectric generating unit regulating system, which comprises the following steps: A nonlinear model of the hydroelectric generating unit considering modeling uncertainty and external disturbance is established. The nonlinear model of the hydroelectric generating unit comprehensively considers the dynamic characteristics of the water turbine, the water pipeline, the servomotor and the generator, and the external disturbance includes load fluctuation and grid frequency change; On the basis of the generator power angle output, a dynamic integral variable related to the servomotor stroke is introduced to construct an extended regulating output function, so as to improve the non-minimum phase characteristic of the hydroelectric generating unit regulating system; The system containing the extended adjustment output function is subjected to coordinate transformation, the system is converted into a chained integral standard form, and a mapping relationship between a virtual control variable and an actual guide vane control input is established; Based on the chained integral standard form, a sliding mode surface is designed, and a control law containing equivalent control and switching control is constructed; wherein, the sliding mode surface represents an ideal dynamic trajectory of the state of the hydroelectric generating unit system, the equivalent control is used to process the nominal system dynamics, and the switching control is used to suppress disturbances; The performance constraint is introduced The performance constraint is introduced The performance constraint represents the suppression ability of the hydroelectric generating unit system to the disturbance; The control law corresponding to the virtual control variable is inverted to the physical control space through the mapping relationship, and a nonlinear robust sliding mode control signal suitable for the hydroelectric generating unit regulation system is obtained; The nonlinear robust sliding mode control signal and the traditional PID control signal are gain-adjustable in parallel superposition to generate a final guide vane opening control instruction, and the final guide vane opening control instruction is output to the guide vane servomotor to perform control operation.

[0006] Optionally, the expression of the nonlinear model of the hydroelectric generating unit is:

[0007]

[0008]

[0009]

[0010] wherein, represents a nonlinear function vector, , represents the power angle of the generator, represents the speed of the generator, represents the power of the hydraulic machine, represents the servomotor stroke, represents the disturbance term, , represents the torque disturbance on the generator shaft, represents the electromechanical disturbance of the hydraulic turbine, represents the disturbance to the follow-up device, represents a state-dependent disturbance coupling matrix, represents a control action matrix, represents a control input signal, represents a system output vector, represents an output equation, represents the rated angular velocity, represents the inertia time constant of the hydro-generator, represents the electromagnetic torque of the generator, represents the damping of the unit, represents the transfer coefficient of the hydro-turbine, represents the inertia time constant of the hydro-turbine, represents the servomotor time constant.

[0011] Optionally, the dynamic integral variable includes a first integral variable and a second integral variable; an expression of the first integral variable is , represents the integral of the servomotor stroke; an expression of the second integral variable is , represents the integral of ; an expression of the extended regulating output function is .

[0012] Optionally, a coordinate transformation is performed on the system including the extended regulating output function, so as to convert the system into a chained integral standard form, including: defining a new state variable ; the chained integral standard form is described by the following expression:

[0013] wherein, represents a virtual control variable.

[0014] Optionally, a mapping relationship between the virtual control variable and an actual guide vane control input is as follows:

[0015]

[0016] wherein, , , , represents a weight parameter.

[0017] Optionally, based on the chained integral standard form, a sliding mode surface is designed, and a control law including equivalent control and switching control is constructed, including: an expression of the sliding mode surface is wherein, represents a positive definite matrix, ; an expression of the control law is as follows:

[0018]

[0019]

[0020] wherein, represents equivalent control, represents switching control, represents system matrix, represents disturbance matrix, represents disturbance upper bound, represents switching gain, represents saturation function, represents boundary layer width.

[0021] Optionally, introducing performance constraints, obtaining the sliding mode surface parameters by solving linear matrix inequalities, including: defining performance output vector ; wherein, represents weight matrix; obtaining positive definite matrix by solving linear matrix inequalities, ensuring that the closed-loop system is robust to disturbances in the sense of guaranteeing disturbance robust performance index meets the preset value of suppression index ; the expression of linear matrix inequality is:

[0022] wherein, is a matrix to be solved, , represents disturbance suppression level, , , represents unit matrix.

[0023] Optionally, the expression of the nonlinear robust sliding mode control signal is:

[0024] wherein, represents nonlinear robust sliding mode control signal.

[0025] Optionally, the nonlinear robust sliding mode control signal is gain-adjustable and parallel superimposed with the traditional PID control signal to generate a final guide vane opening control instruction, including: the expression of the final guide vane opening control instruction is , represents the final guide vane opening control instruction, is an adjustable gain coefficient, represents a traditional PID control signal, the traditional PID control signal is determined according to the system operation mode; wherein, in the power mode, , represents a power setting value, represents an actual power, represents a frequency deviation, represents a tuning coefficient; in the opening mode, , represents an opening setting value, represents a tuning coefficient.

[0026] In a second aspect, the present application provides a control device of a hydroelectric generating set regulating system, which comprises: a model construction module, configured to establish a nonlinear model of the hydroelectric generating set considering modeling uncertainty and external disturbance; the nonlinear model of the hydroelectric generating set comprehensively considers dynamic characteristics of a hydraulic turbine, a hydraulic pipeline, a servomotor and a generator, and the external disturbance includes load fluctuation and power grid frequency variation; an output regulating module, configured to introduce a dynamic integral variable related to servomotor stroke on the basis of generator power angle output, to construct an extended regulating output function, so as to improve non-minimum phase characteristics of the hydroelectric generating set regulating system; a coordinate conversion module, configured to perform coordinate transformation on the system containing the extended regulating output function, to convert the system into a chained integral standard type, and to establish a mapping relationship between a virtual control variable and an actual guide vane control input; a control variable construction module, configured to design a sliding surface based on the chained integral standard type, and to construct a control law containing equivalent control and switching control; wherein the sliding surface represents an ideal dynamic trajectory of the hydroelectric generating set system state, the equivalent control is used to process nominal system dynamics, and the switching control is used to suppress disturbance; a performance constraint module, configured to introduce performance constraints, to obtain sliding surface parameters by solving linear matrix inequalities; wherein the performance constraints represent the suppression ability of the hydroelectric generating set system to disturbance; a control law projection module, configured to inversely project the control law corresponding to the virtual control variable to a physical control space through the mapping relationship, to obtain a nonlinear robust sliding mode control signal suitable for the hydroelectric generating set regulating system; a parallel control module, configured to perform gain-adjustable parallel superposition of the nonlinear robust sliding mode control signal and a traditional PID control signal, to generate a final guide vane opening control instruction, and to output the final guide vane opening control instruction to a guide vane servomotor to perform control operation.

[0027] The present application has at least the following beneficial effects: By establishing a nonlinear model of hydroelectric generating set considering modeling uncertainty and external disturbance, the problem of ignoring system nonlinearity in traditional PID control is effectively solved, which can adapt to complex working conditions such as parameter perturbation and load change, and improve the model accuracy and control adaptability; by introducing integral variable and constructing new regulating output function, the system zero dynamic order is effectively reduced, the inherent non-minimum phase problem of hydroelectric generating set is solved, and the stability of hydroelectric generating set regulating system is improved; combined with sliding mode control and Performance constraints not only ensure the rapid response characteristics of the system, but also provide certain disturbance suppression capability, which significantly improves the dynamic performance and robustness of the system; through the parallel structure of nonlinear controller and PID controller, the advantages in dynamic regulation are maintained, and the reliability of traditional PID in steady state control is inherited, and the optimization balance of control performance is realized. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings are used to provide a further understanding of the technical solutions of the present application, and constitute a part of the specification, and are used to explain the technical solutions of the present application together with the embodiments of the present application, and do not constitute a limitation on the technical solutions of the present application.

[0029] Figure 1 The flow chart of the control method of the hydroelectric generating set regulating system in one of the embodiments of the present application is shown in the figure. Figure 2 The structural schematic diagram of the control device of the hydroelectric generating set regulating system in another embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0031] Currently, the traditional PID control method is generally used in the speed regulation system of a hydroelectric generating unit. This control strategy is designed based on a linearized model of the system, has a simple structure and is easy to implement, and has been applied in engineering for many years. The traditional PID controller processes the deviation between the system output and the set value through three links of proportion, integration and differentiation, generates a control signal to drive the servomotor to adjust the guide vane opening. In actual application, the parameters of the PID controller are usually set under specific working conditions, and the proportion coefficient Kp, the integration coefficient Ki and the differentiation coefficient Kd are mainly determined by engineering experience. However, the traditional PID controller often ignores the uncertainty factors in the system model, such as parameter perturbation and model linearization error, and cannot effectively cope with various disturbances and nonlinear characteristics in the actual running conditions, resulting in a decline in control performance. In addition, the hydroelectric generating unit system has inherent non-minimum phase characteristics, which is manifested as unstable system zero dynamics, which is a fundamental problem that cannot be solved by the existing technology. The traditional PID control method cannot guarantee the internal stability of the non-minimum phase system, resulting in oscillation or even instability of the system in the dynamic process. The existing technology cannot effectively integrate the rapidity of the sliding mode control and the robustness of the control. The use of sliding mode control alone is prone to high-frequency chattering, while the use of control alone often sacrifices the rapidity and reachability of the system. In view of the defects of the prior art, the present application provides a control method for a hydroelectric generating unit regulation system, which effectively solves the problem of ignoring the nonlinearity of the system by the traditional PID control by establishing a nonlinear model of the hydroelectric generating unit considering modeling uncertainty and external disturbance, can adapt to complex working conditions such as parameter perturbation and load variation, and improves the model accuracy and control adaptability; by introducing an integral variable and constructing a new regulation output function, the order of the system zero dynamics is effectively reduced, the inherent non-minimum phase problem of the hydroelectric generating unit is solved, and the stability of the hydroelectric generating unit regulation system is improved; by combining sliding mode control and performance constraints, the rapid response characteristics of the system are guaranteed, and the disturbance suppression ability is provided, which significantly improves the dynamic performance and robustness of the system; through the parallel structure of the nonlinear controller and the PID controller, the advantages in dynamic regulation are maintained, and the reliability of the traditional PID in steady-state control is inherited, realizing the optimal balance of control performance.

[0032] Embodiment 1 As Figure 1 shown, the control method for the hydroelectric generating unit regulation system provided by the present application specifically includes the following steps: Step 11, a nonlinear model of the hydroelectric generating unit considering modeling uncertainty and external disturbance is established.

[0033] It should be noted that in the embodiments of the present application, the nonlinear model of the hydroelectric generating unit comprehensively considers the dynamic characteristics of the water turbine, the hydraulic pipeline, the servomotor and the generator, and the external disturbances include load fluctuation and grid frequency variation.

[0034] In actual implementation, firstly, real-time physical quantities of the hydroelectric generating unit are collected through the pre-installed sensors. For example, the generator power angle is obtained through a phase measurement unit PMU , the generator speed is obtained through a speed sensor , the generator electromagnetic torque is obtained through a water turbine torque sensor , the servomotor stroke is obtained through a displacement sensor , and these sensor signals are collected at a fixed sampling period (for example, 10-53 ms). Based on the physical quantities of the sensors, the nonlinear model of the hydroelectric generating unit considering modeling uncertainty and external disturbance is established, and the model parameters of the nonlinear model of the hydroelectric generating unit can be determined through unit design data. For example, the rated angular velocity is usually 314 rad / s, corresponding to a 50 Hz system; the typical value of the water-turbine-generator inertia time constant is 2-10 s; the typical value of the water turbine inertia time constant is 0.5-2 s; the typical value of the servomotor time constant is 0.1-0.5 s; the water turbine transmission coefficient can be obtained by fitting the water turbine characteristic curve; and the motor electromagnetic torque is calculated from the grid-side power and voltage.

[0035] In a feasible implementation manner, the model adopts a linear six-transmission-coefficient water turbine model, a first-order servomotor model and a second-order generator model:

[0036] wherein, denotes a damping coefficient, denotes a control input signal.

[0037] Then, the unmodeled dynamics and working condition disturbances are aggregated and the disturbance term is considered, to form the following nonlinear affine system:

[0038] wherein, ； ；

[0039]

[0040] wherein, represents a nonlinear function vector, , represents a disturbance term, , represents a torque disturbance on the generator shaft, represents an electro-mechanical disturbance of the hydraulic turbine, represents a disturbance to the servo, represents a state-dependent disturbance coupling matrix, represents a control action matrix, represents a system output, represents a system output equation, represents a unit damping.

[0041] It is worth mentioning that the nonlinear model of the hydroelectric unit established by the present application, on the one hand, fully considers the coupled dynamics of the hydraulic turbine, the water diversion system, the servomotor and the generator, avoids the simplification error of the traditional linear model, and provides a real basic model for subsequent controller design. By introducing physical parameters, the nonlinear model of the hydroelectric unit can accurately reflect the key characteristics such as water hammer effect and inertia, thereby improving the accuracy of control. On the other hand, the system is represented in a standard affine form, which explicitly includes modeling uncertainties and external disturbances, so that the controller design can directly handle these factors, thereby enhancing the robustness of the system. The introduction of the disturbance term avoids the defects of the traditional method of ignoring uncertainties, and improves the reliability of the control in actual working conditions.

[0042] Step 12: On the basis of the generator power angle output, a dynamic integral variable related to the servomotor stroke is introduced to construct an extended regulation output function, so as to improve the non-minimum phase characteristic of the hydroelectric unit regulation system.

[0043] In the embodiment of the present application, in order to overcome the non-minimum phase characteristic of the system, a first integral variable and a second integral variable are introduced on the basis of the original output , the first integral variable represents the integral of the servomotor stroke, and the second integral variable represents the integral of the integral of the servomotor stroke; the expression of the first integral variable is , and the expression of the second integral variable is ; on this basis, the expression of the extended regulation output function is .

[0044] It is worth mentioning that the extended regulation output function is expanded by integration, and the zero dynamic order of the system is reduced from the original high order, thereby ensuring the stability of the zero dynamic. The extended regulation output function couples the slowly varying integral with the fast varying power angle, improves the controllability of the system, solves the control difficulty caused by the non-minimum phase problem of the hydroelectric unit, and lays a foundation for coordinate transformation.

[0045] Step 13. Coordinate transformation is performed on the system containing the extended manipulated output function, and the system is converted into a chained-integrator normal form, and a mapping relationship between the virtual control variable and the actual guide vane control input is established.

[0046] In one possible implementation, a new state variable is first defined as where the derivative is calculated by numerical differentiation (e.g. using a first-order difference with low-pass filtering to reduce noise).

[0047] Subsequently, the system is transformed into a chained-integrator normal form, which is expressed as

[0048] where represents the virtual control variable.

[0049] The mapping relationship between the virtual control variable and the actual guide vane control input is as follows:

[0050] The parameters , , , represent weight parameters, which are calculated from the system parameters:

[0051] In one possible implementation, the parameters , , , are calculated offline and stored as a constant table.

[0052] It is worth mentioning that in the embodiments of the present application, the coordinate transformation converts the nonlinear system into a linear normal form, simplifying the controller design. The chained-integrator form makes the system state in a series structure, facilitating the application of sliding mode control theory. The virtual control variable v decouples the system dynamics, making the control law design more intuitive and efficient.

[0053] Step 14. Based on the chained-integrator normal form, a sliding surface is designed, and a control law containing equivalent control and switching control is constructed.

[0054] where the sliding surface represents the ideal dynamic trajectory of the hydroelectric generating unit system state, the equivalent control is used to handle the nominal system dynamics, and the switching control is used to suppress disturbances.

[0055] Specifically, the expression of the sliding surface is where represents a positive definite matrix, .

[0056] The expression of the control law is

[0057]

[0058]

[0059] where, denotes equivalent control, denotes switching control, denotes system matrix (constant matrix in chain form), denotes disturbance matrix, denotes disturbance upper bound, denotes switching gain (typical value is 0.01-0.1), denotes saturation function, denotes boundary layer width (typical value is 0.05-0.2). handling nominal system dynamics, handling disturbances and uncertainties, In an available implementation, saturation function .

[0060] It is worth mentioning that in the embodiments of the present application, the equivalent control ensures the ideal dynamics of the system on the sliding surface, and the switching control suppresses the disturbances and uncertainties. The introduction of the saturation function avoids the high-frequency chattering caused by the traditional sign function, makes the control signal smooth, and improves the actuator life and system stability.

[0061] Step 15, introducing performance constraints, and obtaining the sliding surface parameters by solving linear matrix inequalities.

[0062] where, The performance constraint represents the suppression ability of the hydroelectric generating unit system to the disturbance.

[0063] Specifically, the performance output vector is defined; wherein, denotes the weight matrix, which is selected according to the control target. Exemplarily, is used to emphasize the state deviation, , is used to balance the control energy.

[0064] The linear matrix inequality is solved to obtain a positive definite matrix , which ensures the disturbance robustness in the sense of the closed-loop system to the disturbance The performance index satisfies the preset value suppression index ; the expression of the linear matrix inequality is:

[0065] wherein, is the matrix to be solved, , represents the disturbance rejection level (typical value is 0.1-1.0), , , represents the identity matrix. In actual implementation, the linear matrix inequality (LMI) can be solved offline using convex optimization tools (such as the LMI toolbox of MATLAB).

[0066] It is worth mentioning that, The constraint ensures that the system is from the disturbance The gain of the performance output is less than , which enhances the robustness of the system to parameter perturbation and external disturbance. The LMI solution provides the optimal sliding surface parameters, which minimizes the control energy while ensuring performance.

[0067] Step 16, the control law corresponding to the virtual control quantity is inverted to the physical control space through the mapping relationship, obtaining the nonlinear robust sliding mode control signal suitable for the hydroelectric generating unit regulation system.

[0068] Specifically, the virtual control quantity is mapped back to the physical control input , and the expression of the obtained nonlinear robust sliding mode control signal is:

[0069] wherein, represents the nonlinear robust sliding mode control signal. Among them, all parameters and states are known, and in actual implementation, the can be calculated in real time.

[0070] It is worth mentioning that the virtual control quantity is converted into the actual control input, so that the controller can directly act on the hydroelectric generating unit. The analytical expression of the control law is clear, which depends on the local measurable, and is convenient for engineering implementation. The nonlinear feedback term compensates for the system dynamics, improving the control accuracy Step 17, the nonlinear robust sliding mode control signal and the traditional PID control signal are gain-adjustable in parallel superposition to generate the final guide vane opening control command, and the final guide vane opening control command is output to the guide vane servomotor to perform control operation.

[0071] In a feasible implementation, the expression of the final guide vane opening control command is , represents the final guide vane opening control command, is an adjustable gain coefficient, represents a traditional PID control signal, the traditional PID control signal being determined according to a system operation mode; wherein, in the power mode, , represents a power set value, represents an actual power, represents a frequency deviation, represents a tuning coefficient. in the opening mode, , represents an opening set value, represents a tuning coefficient.

[0072] in actual implementation, the final control signal is output to a servomotor after being subjected to amplitude limiting (for example, -1 to 1 p.u.) and adjusting the guide vane opening.

[0073] It is worth mentioning that the parallel structure combines the fast anti-disturbance ability of the NRSMC and the steady-state accuracy of the PID, so that the system performs excellently in both dynamic and steady-state conditions. The gain-adjustable mechanism enhances the adaptability of the controller and facilitates smooth switching between different operation modes. This improves the frequency response and power tracking performance of the hydroelectric generating unit.

[0074] Through the above steps, the present application realizes the nonlinear robust control of the hydroelectric generating unit regulating system. In implementation, all calculations are based on local measurements and do not depend on network parameters, and have the ability to be implemented in a decentralized manner. The controller is deployed on a DCS or PLC platform and runs in real time, ensuring the stability and reliability of the system. Experiments show that, compared with the traditional PID control, the dynamic response speed is increased by more than 30% and the anti-disturbance ability is enhanced by 50%, so the present application is suitable for large and medium-sized hydropower stations and pumped storage power stations.

[0075] Embodiment 2 In the embodiments of the present application, a control device for a hydroelectric generating unit regulating system is disclosed. As shown in Figure 2 the control device 200 comprises: a model construction module 201 configured to establish a hydroelectric generating unit nonlinear model considering modeling uncertainty and external disturbance; the hydroelectric generating unit nonlinear model comprehensively considers the dynamic characteristics of a hydraulic turbine, a hydraulic pipeline, a servomotor and a generator, and the external disturbance includes load fluctuation and grid frequency variation; an output adjustment module 202 configured to introduce a dynamic integral variable related to servomotor stroke on the basis of generator power angle output, construct an extended adjustment output function, and improve the non-minimum phase characteristic of the hydroelectric generating unit regulating system; a coordinate conversion module 203 configured to perform coordinate transformation on the system containing the extended adjustment output function, convert the system into a chain integral standard type, and establish a mapping relationship between a virtual control variable and an actual guide vane control input. The control amount construction module 204 is configured to design a sliding mode surface based on a chain integral standard type, and construct a control law comprising equivalent control and switching control; wherein the sliding mode surface represents an ideal dynamic trajectory of the state of the hydroelectric generating unit system, the equivalent control is used to process nominal system dynamics, and the switching control is used to suppress disturbances; The performance constraint module 205 is configured to introduce performance constraints, and obtain sliding mode surface parameters by solving a linear matrix inequality; wherein The performance constraints represent the suppression capability of the hydroelectric generating unit system to disturbances; The control law projection module 206 is configured to inversely project the control law corresponding to the virtual control amount to a physical control space through a mapping relationship, to obtain a nonlinear robust sliding mode control signal suitable for the hydroelectric generating unit regulating system; The parallel control module 207 is configured to perform gain-adjustable parallel superposition of the nonlinear robust sliding mode control signal and a traditional PID control signal, to generate a final guide vane opening control instruction, and output the final guide vane opening control instruction to a guide vane servomotor to perform control operations.

[0076] It should be noted that the information interaction, execution process and the like between the above devices / units are based on the same concept as the method embodiments of the present application, and the specific functions and the technical effects brought by the same can be referred to the method embodiments part, which will not be described herein. It can be clearly understood by those skilled in the art that, for the convenience and brevity of description, only the division of the above functional units and modules is taken as an example for illustration, and in actual application, the above functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit. In addition, the specific names of the functional units and modules are only for mutual distinction, and do not limit the protection scope of the present application. The specific working process of the units and modules in the system can be referred to the corresponding process in the foregoing method embodiments, which will not be described herein.

[0077] Compared with the prior art, the present application has the following obvious advantages: 1. The output function based on integral expansion effectively solves the non-minimum phase problem, and improves the controllability and response stability of the system; 2. The sliding mode control structure is introduced to enhance the robustness and anti-disturbance performance of the system; 3. The controller form is explicit, the control law can be expressed analytically, and has good realizability; 4. The variables used are all local measurable signals, facilitating engineering distributed deployment; 5. The parallel PID structure improves the compatibility and flexible adjustment ability of the control strategy; Scope of application: The application is suitable for large and medium-sized hydropower stations, pumped storage power stations and the like, and is especially suitable for deployment in power systems with significant structural nonlinearity, strong model uncertainty and frequent operation disturbances, and is suitable for application directions such as upgrading of main machine governors, intelligent regulation and control systems for newly-built hydropower units and the like.

[0078] Those skilled in the art should understand that the discussion of the above any embodiment is only exemplary, and is not intended to imply that the protection scope of the application is limited to these examples; under the idea of the application, the above embodiments or technical features in different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of one or more embodiments of the application as described above, which are not provided in details for the sake of brevity.

[0079] One or more embodiments of the application are intended to cover all such alternatives, modifications and variations falling within the broad scope of the application. Therefore, any omission, modification, equivalent replacement, improvement and the like made within the spirit and principles of one or more embodiments of the application should be included in the protection scope of the application.

Claims

1. A control method for a hydroelectric generating unit regulating system, characterized by, The application relates to a control device and a control method of a hydroelectric generating unit. The application comprises: A nonlinear model of a hydroelectric generating unit is established, which considers modeling uncertainty and external disturbances; the nonlinear model of the hydroelectric generating unit comprehensively considers dynamic characteristics of a hydraulic turbine, a hydraulic pipeline, a servomotor and a generator, and the external disturbances include load fluctuation and power grid frequency variation; On the basis of a generator power angle output, a dynamic integral variable related to servomotor stroke is introduced, and an extended regulating output function is constructed to improve non-minimum phase characteristics of the hydroelectric generating unit regulating system; A coordinate transformation is performed on a system containing the extended regulating output function, the system is converted into a chained integral standard type, and a mapping relationship between a virtual control variable and an actual guide vane control input is established; Introduction performance constraints, the sliding surface parameters are obtained by solving linear matrix inequalities; wherein the The performance constraints represent the ability of the hydroelectric unit system to suppress disturbances. Based on the chained integral standard type, a sliding surface is designed, and a control law containing equivalent control and switching control is constructed; the sliding surface represents an ideal dynamic trajectory of a hydroelectric generating unit system state, the equivalent control is used to process nominal system dynamics, and the switching control is used to suppress disturbances; The control law corresponding to the virtual control variable is inverted to a physical control space through the mapping relationship, and a nonlinear robust sliding mode control signal suitable for the hydroelectric generating unit regulating system is obtained; 2. The control method of a hydroelectric generating unit regulating system according to claim 1, characterized in that, The nonlinear robust sliding mode control signal and a traditional PID control signal are gain-adjustably connected in parallel, a final guide vane opening control instruction is generated, and the final guide vane opening control instruction is output to the guide vane servomotor to perform a control operation. wherein denotes a nonlinear function vector, , denotes a generator power angle, denotes a generator speed, denotes a hydraulic machine power, denotes a servomotor stroke, denotes a disturbance term, , denotes a torque disturbance on the generator shaft, denotes an electro-mechanical disturbance of the hydraulic turbine, denotes a disturbance to the servomotor, denotes a state-dependent disturbance coupling matrix, denotes a control action matrix, denotes a control input signal, denotes a system output, denotes a system output equation, denotes a rated angular velocity, denotes a hydro-generator inertia time constant, denotes a generator electromagnetic torque, denotes a machine damping, denotes a hydraulic turbine transfer coefficient, denotes a hydraulic turbine inertia time constant, denotes a servomotor time constant.

3. The control method of a hydroelectric generating unit regulating system according to claim 2, characterized in that, The dynamic integral variable includes a first integral variable and a second integral variable; an expression of the first integral variable is , represents an integral of a servomotor stroke; an expression of the second integral variable is , represents an integral of The expression of the extended adjustment output function is .

4. The control method of a hydroelectric generating unit regulating system according to claim 3, characterized in that, The expression of the nonlinear model of the hydroelectric generating unit is as follows: Defining new state variables ; The coordinate transformation performed on the system containing the extended regulating output function to convert the system into the chained integral standard type comprises: wherein represents a virtual control variable.

5. The control method of a hydroelectric generating unit regulating system according to claim 4, characterized in that, The chained integral standard type is described by the following expression: wherein , , , denotes a weight parameter.

6. The control method of a hydroelectric generating unit regulating system according to claim 5, wherein, The mapping relationship between the virtual control variable and the actual guide vane control input is as follows: The expression of the sliding surface is wherein, denotes a positive definite matrix, ; The control law The expression is: wherein, denotes equivalent control, denotes switching control, denotes system matrix, denotes disturbance matrix, denotes disturbance upper bound, denotes switching gain, denotes saturation function, denotes boundary layer width.

7. The control method of a hydroelectric generating unit regulating system according to claim 6, characterized in that, The introduction Performance constraints, the sliding surface parameters are obtained by solving linear matrix inequalities, including: defining a performance output vector ; wherein, denotes a weight matrix; A positive definite matrix is obtained by linear matrix inequality solving , which ensures that the closed-loop system is robust to disturbance in the sense of guaranteeing disturbance robust performance index to meet a preset value suppression index ; and an expression of the linear matrix inequality is: wherein is the matrix to be solved, , denotes the disturbance rejection level, , , denotes the identity matrix.

8. The control method of a hydroelectric generating unit regulating system according to claim 7, characterized in that, Based on the chained integral standard type, the sliding surface is designed, and the control law containing the equivalent control and the switching control comprises: wherein, denotes the nonlinear robust sliding mode control signal.

9. The control method of a hydroelectric generating unit regulating system according to claim 8, characterized in that, The expression of the nonlinear robust sliding mode control signal is as follows: The expression of the final guide vane opening control instruction is , represents the final guide vane opening control instruction, is an adjustable gain coefficient, represents a traditional PID control signal, which is determined according to a system operation mode; wherein, In power mode, , denotes a power set value, denotes an actual power, denotes a frequency deviation, denotes a tuning coefficient; In the opening mode, , denotes the opening set value, denotes the correction factor.

10. A control device for a hydroelectric generating unit regulating system, characterized by The nonlinear robust sliding mode control signal and the traditional PID control signal are gain-adjustably connected in parallel to generate the final guide vane opening control instruction, which comprises: The control device comprises: A model construction module is configured to establish a nonlinear model of a hydroelectric generating unit considering modeling uncertainty and external disturbances; the nonlinear model of the hydroelectric generating unit comprehensively considers dynamic characteristics of a hydraulic turbine, a hydraulic pipeline, a servomotor and a generator, and the external disturbances include load fluctuation and power grid frequency variation; An output regulating module is configured to introduce a dynamic integral variable related to servomotor stroke on the basis of a generator power angle output, and construct an extended regulating output function to improve non-minimum phase characteristics of the hydroelectric generating unit regulating system; A coordinate conversion module is configured to perform coordinate transformation on a system containing the extended regulating output function, convert the system into a chained integral standard type, and establish a mapping relationship between a virtual control variable and an actual guide vane control input. The control amount construction module is configured to design a sliding mode surface based on the chain integral standard form, and construct a control law comprising equivalent control and switching control; wherein the sliding mode surface represents an ideal dynamic trajectory of a state of the hydroelectric generating unit system, the equivalent control is used to process nominal system dynamics, and the switching control is used to suppress disturbances; a performance constraint module configured to introduce a performance constraint, the sliding mode surface parameters are obtained by solving a linear matrix inequality; wherein the the performance constraint represents the ability of the hydroelectric generating unit system to suppress disturbances; The control law projection module is configured to inversely project the control law corresponding to the virtual control amount to a physical control space through the mapping relationship, to obtain a nonlinear robust sliding mode control signal applicable to the hydroelectric generating unit regulating system; The parallel control module is configured to perform gain-adjustable parallel superposition of the nonlinear robust sliding mode control signal and a traditional PID control signal, to generate a final guide vane opening control instruction, and output the final guide vane opening control instruction to the guide vane servomotor to perform a control operation.

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