673 results about "Steady state error" patented technology

A technique is disclosed for reducing an error in a controlled variable via model predictive control. A predicted error in the controlled variable is determined for a forward-looking control horizon based upon measured or computed variables. The integral of the predicted error is computed. If the error or the integral exceed a tolerance for a determined time period, the model predictive control algorithm is modified to drive the error or the integral to within a tolerance. The modifications to the control algorithm may include changes to coefficients for terms based upon the error and / or the integral of the error.

A technique is disclosed for reducing an error in a controlled variable via model predictive control. A predicted error in the controlled variable is determined for a forward-looking control horizon based upon measured or computed variables. The integral of the predicted error is computed. If the error or the integral exceed a tolerance for a determined time period, the model predictive control algorithm is modified to drive the error or the integral to within a tolerance. The modifications to the control algorithm may include changes to coefficients for terms based upon the error and / or the integral of the error.

The invention relates to raw material grinding in the field of cement process industries, and aims to provide an advanced control method and system for a vertical mill based on model identification and predictive control. The method comprises the following steps of: acquiring real-time data from a distributed control system (DCS) monitoring system; analyzing a variation trend of the operation and technology parameters, and then invoking a pathological working condition expert database for performing trend matching; if a pathological working condition appears, issuing early warning display and giving qualitative adjustment suggestion remind; giving an optimal target set value according to the basic operation condition of the vertical mill and the variation situation of the product quality requirement, and writing into a predictive controller; setting an optimal controlled quantity output according to the optimal target set value, and outputting to the DCS monitoring system to control a field actuator to take action. By adopting the invention, the qualitative adjustment suggestion can be precisely given; a mathematical model of the grinding process of the vertical mill is established and updated in real time; the steady-state error of the control system is reduced; and the grinding process of the vertical mill is instructed, so that the mill can operate stably for long term at a maximum efficiency point, and stable margin is maintained.

The invention provides a network voltage disturbance generating device, which comprises a three-phase bridge type PWM (Pulse Width Modulation) rectifier and a three-H-bridge three-phase four-wire-system PWM inverter, wherein the alternating current side of the rectifier is connected with an electric network through an L type filter; the direct current side of the rectifier is connected in series with the direct current side of the three-H-bridge three-phase four-wire-system PWM inverter; an LC filter is connected to the alternating current side of the three-H-bridge three-phase four-wire-system PWM inverter; the output end of the LC filter is connected with an isolation transformer; and the secondary side of the isolation transformer is connected with a load. The invention further provides a control method suitable for the device. Due to the adoption of the device provided by the invention, the simulation of a network voltage amplitude, frequency disturbance and an electric network harmonic phenomenon can be realized, bilateral flow of energy can be realized, and active energy transmitted by tested solar-powered grid-connected equipment is fed back to the electric network; and the control method is easy and convenient to implement, and a target reference value can be accurately tracked; and moreover, quick response and small steady-state errors are realized, so that electric network disturbance can be simulated accurately.

The invention discloses an air conditioner control method, an air conditioner control device and an air conditioner. The control method includes the steps that the indoor environment temperature and the outdoor environment temperature are detected; the difference value delta T between the indoor temperature and the temperature set by a user is computed; the operating time of the air conditioner is detected; when the operating time is smaller than a preset time, the fuzzy control coefficient of a compressor is computed according to the difference value delta T, the outdoor environment temperature and a preset fuzzy control rule, and the operating frequency of the compressor is computed according to the fuzzy control coefficient; and when the operating time is larger than or equal to the preset time, the operating frequency correction value of the compressor is computed according to the difference value delta T and a preset PI control model, and the operating frequency correction value is added to the operating frequency to control the compressor to operate according to the corrected operating frequency. According to the control method, fuzzy control and PI control are combined to control the compressor so that the compressor can achieve a better control effect; and the precision of steady control is guaranteed and the steady state error is eliminated while the higher response speed is achieved.

The invention discloses an LCL-type single-phase grid-connected inverter power control and active damping optimization method. An equivalent synchronous coordinate PI controller is adopted, a two-phase virtual orthogonal system is constructed by adopting an all-pass filter, the problem that data used in previous construction methods have asynchrony or noise interference is introduced is solved, regulation of grid-connected currents at fundamental frequency in a zero steady state error is achieved, and the stability of the system is improved. According to the LCL-type single-phase grid-connected inverter power control and active damping optimization method, the primary differential and the high-frequency components of the grid-connected currents are fed back in real time, the damping of the system is increased, the resonance peak of the LCL filter is restrained, an optimized parameter selection method is given, single-current feedback factors are reduced to a variable, the defect that parameters are difficult to select in single current high-frequency component feedback is overcome, and the reliability and the dynamic nature of the system are improved.

The invention relates to a variable-step self-adaptive EASI blind source separation processing method, belonging to the technical field of signal processing. The method adopts a minimum mean square error criterion to estimate a global matrix reflecting separation precision to control step length; and compared with the traditional EASI algorithm, the method overcomes the inherent contradiction between the convergence velocity and the steady-state error of the traditional EASI algorithm. The invention can precisely separate composite signals, raise the convergence velocity, reduce the steady-state error and achieve better stability. The invention has wide application prospects in the fields of wireless communication signal processing, radar signal processing, image signal processing, speech signal processing and the like.

A control method of a net-side rectifier of a double-fed asynchronous wind power generator designed by the invention can realize zero steady-state error tracking of zero frequency and frequency-doubled component in an input signal of a forward channel as well as the complete attenuation of zero frequency and frequency-doubled interference by changing a traditional PI adjustor to a PIR adjustor and setting a set frequency Omega[c] in the PIR adjustor to a double synchronous rotation angular speed Omega[s], thus relieving the influence caused by harmonic generated due to unbalanced network voltage. Only through the replacement of the adjustor, the method realizes the control over the net-side rectifier of the generator under the condition of unbalanced network voltage, is simple in modification and obvious in effect, does not relate to the design of complicated parts and is easy for implementation.

The invention relates to the technical field of parameter optimization of a PID (proportional-integral-derivative) controller, in particular to a method of parameter optimization of a speed regulating system of a water turbine based on satisfying control, belonging to the technical field of parameter optimization of the PID controller; the invention collects the performance indexes of rising time, overshoot, adjusting time and steady state error which are responded by the water turbine system according to the data which is required by the specific performance indexes of the water turbine system; then a satisfaction function of all the performance indexes can be obtained; the actual operation results of the system are taken as the standard to design and optimize the parameter of the controller; a genetic algorithm model which takes the total satisfaction function of the system performance indexes as fitness is established; the method of parameter optimization of the speed regulating system of the water turbine based on satisfying control is proposed by the simulation, contrast and analysis of three parameter optimization design methods and the total satisfaction meets the PID parameter which is required by the design; although the system designed by the invention does not have the necessity of operating in the optimized working condition, the actual requirement can be met better, and the cost of optimization can be reduced greatly, therefore, the invention has practicability and is easy to realize.

The invention belongs to the technical field of wind power generation, and discloses a comprehensive control system adopting a doubly-fed wind generator participated in power grid primary frequency modulation. The control system comprises a rotor rotary speed control module, a simulation inertia control module, a droop control module, a rotary speed protection and power determination module and apitch angle control module. After the wind generator is participated in frequency modulation, the power grid inertia is equivalently enlarged, so that the doubly-fed asynchronous wind generator can have inertia response on the power grid frequent as the conventional synchronous generator, thereby lowering change rate of the power grid frequency; and by controlling the rotary speed and the pitch angle, the wind generator output is lowered, so that the wind generator has certain active backup capacity to be participated in primary frequency modulation, thereby lowering steady-state error of thefrequency.

The invention discloses a tension roll control device for a plate and strip processing line and a tension control method, belonging to the field of tension control of tension rolls on the plate and strip processing line in the metallurgical industry. The tension roll control device comprises a tension roll group, an auxiliary roll frequency converter and a main roll frequency converter, and further comprises an auxiliary roll speed encoder, a main roll speed encoder, a load distributor, a tension regulator, a feedforward compensation unit and a tensiometer, wherein two ends of the load distributor are respectively connected with the auxiliary roll frequency converter and the main roll frequency converter; the auxiliary roll frequency converter comprises an auxiliary roll rotation speed control unit and an auxiliary roll torque control unit; and the main roll frequency converter comprises a main roll rotation speed control unit and a main roll torque control unit. The tension roll control device has the advantages of high control response speed and high control precision. A control method of the tension roll control device comprises the steps of: (1) main / slave load distribution for the tension rolls; (2) complex tension control of the tension rolls; and (C) dynamic compensation. The method has the advantages of small steady state error of a torque loop, short anti-disturbance recover time, constant rotation speed and good anti-disturbance performance.

A harmonics attenuator employing a combination controller that incorporates features of a classic controller and a state space controller to function as a hybrid controller unit. The PID portion of the classic controller regulates the steady state error and is separated from the pulse width modulated constant frequency signal generator that also comprises part of the classic controller. The PID portion is coupled with a state space controller such that the output of the PID controller, i.e., the steady state error correction, is input to the state space controller. The state space controller further receives as input variables a reference sinusoidal signal, the load current, the current across a pre-load filter capacitor, and the output voltage. From these inputs, the state space controller generates a transient error correction that is fed to a PWM signal generator for generating a sinusoidal output voltage signal with both steady state and transient error correction. The combination controller is thusly incorporated into an electrical feedback system referred to as a harmonics eater to attenuate higher order harmonics in an AC driven system.

The invention discloses a current compensation based power decoupling method of a virtual synchronous power generator. The power decoupling method comprises the following steps of 1) acquiring a dq component of an output current of a virtual synchronous motor through sampling, acquiring power angle information by a mechanical property simulation part, and further calculating reactive power-power angle decoupling current compensation instruction; 2) acquiring transient state variable quantity of a virtual excitation electromotive force, and calculating active power-voltage decoupling current compensation instruction by combining the dq component, obtained in the step 1), of the output current; and 3) correcting the reactive power-power angle decoupling current compensation instruction obtained in the step 1) and the active power-voltage decoupling current compensation instruction obtained in the step 2) to obtain a new current instruction, and obtaining a switching signal through a current ring to drive a switching network. The invention proposes the power decoupling method applicable to the virtual synchronous motor, and the influence of a power angle on droop control can be eliminated; and compared with the prior art, the power decoupling method has the advantages that dynamic power oscillation and a steady-state error brought by power coupling can be eliminated.

A technique is disclosed for reducing an error in a controlled variable via model predictive control. A predicted error in the controlled variable is determined for a forward-looking control horizon based upon measured or computed variables. The integral of the predicted error is computed. If the error or the integral exceed a tolerance for a determined time period, the model predictive control algorithm is modified to drive the error or the integral to within a tolerance. The modifications to the control algorithm may include changes to coefficients for terms based upon the error and / or the integral of the error.

The invention provides a gradient variable-step LMS self-adaptation filtering method. The method includes the steps that (1) input signals X(n)+{x(n), x(n-1), ..., x(n-m+1)} are signal vectors formed by delays at different moments, wherein x(n) is a sampling value of a first-order filter at the n moment, and m is the order of a transversal filter; (2) the input signals are multiplied by corresponding weighted values and then summation is conducted to obtain an actual system output value y(n), and all weight vectors are initialized to be zero; (3) y(n) is subtracted from d(n) to obtain error signals e(n); (4) smooth gradient vectors g(n) are obtained; (5) the smooth gradient vectors at the adjacent moments are multiplied to obtain iterative step parameters at the n moment; (6) a weighted vector at the moment is obtained; (7) cyclic computing is conducted from the first step to the sixth step, then iterative computation is conducted and results are output. Through the gradient variable-step LMS self-adaptation filtering method, fast convergence on the premise of not reducing steady state errors is achieved.

The invention discloses a detection method for a variable step length LMS (Least Mean Square) harmonic current based on versiera. The method comprises the steps of: sampling, estimating an active current of a fundamental wave, estimating a general harmonic current, updating a weight coefficient, updating the step length and iterating. According to the orthogonal characteristics of a trigonometric function, the current error output by a filter and an instantaneous cross-correlation time mean value are subtracted from a load current to eliminate interference of the harmonic current and the active current of the fundamental wave on update of the step length. Furthermore, update of the step length is controlled by an improved versiera function. Meanwhile, in the updating process of the weight coefficient, variation of the weight coefficient is imported so that the steady state error is very small and the calculated amount is smaller. The detection method for the variable step length LMS harmonic current based on versiera provided by the invention is suitable for occasion where the load current has saltus and value of the optimal parameter provided by the invention is less dependent on the load current.

The invention provides a three-phase voltage type rectifier and a control method thereof. Through providing the high-robustness three-phase voltage type rectifier, a better inhibition effect on both overshooting and steady state error of a system is achieved while the high utilization rate of the voltage of an electric grid is guaranteed. The three-phase voltage type rectifier and the control method thereof have the following advantages: 1, the utilization rate of the electric grid can be increased by 15.4% through adopting an SVPWM (Space Vector Pulse Width Modulation) method compared with that achieved by an ordinary PWM (Pulse Width Modulation) method; 2, a voltage loop adopts a sliding-mode variable structure control (VSC) algorithm to replace the traditional PID (Proportion Integration Differentiation) control algorithm, thus the three-phase voltage type rectifier can rapidly respond to the voltage change of a direct current side; and 3, the voltage loop adopts a PID and VSC combined control method to replace the traditional PID control algorithm, so that the three-phase voltage type rectifier can rapidly respond to current change and can output stable control signals, and then, the overshooting and steady state error of the direct current side are reduced.

The invention discloses a composite PID fuzzy control method applied to a transformer cooling system. The method comprises the following steps of obtaining a temperature value through a thermodetector; solving input quantity deviation E and deviation change EC, performing fuzzification after quantization; calculating a fuzzy control table, and checking the fuzzy control table to obtain the fuzzy control quantity; solving the practical control quantities , and , and making the ,the and the serve as the input quantities of PID; solving the control quantity y(t) and outputting the control quality to a frequency converter. According to the composite PID fuzzy control method applied to the transformer cooling system, the fuzzy control and the PID control are combined, the fuzzy control is introduced on the basis of the conventional PID control to form the composite PID fuzzy control method, the dynamic response speed is increased by utilizing the proportional control of PID, and steady state errors are eliminated by utilizing the integral control of PID, so that the steady-state performance of the fuzzy control is improved, and the energy-saving effect of the operation of the transformer cooling system is further improved.

The invention discloses an adaptive echo cancellation method adopting memory proportionate affine projection and based on M-estimation. The adaptive echo cancellation method comprises the following steps: A, a remote signal is sampled; B, in echo estimation, a filter input vector X(n) passes through an adaptive filter and an output value y(n), namely an echo estimation value y(n), is obtained and equal to XT(n)w(n); C, in echo cancellation, a near-end signal d(n) with the echo, acquired by a near-end microphone and the output value y(n) of the adaptive filter are subjected to subtraction operation, and a return signal, namely a residual signal e(n), is returned to a far end and equal to d(n)-y(n); D, in updating of a tap weight vector of the filter, the method adopting memory proportionate affine projection and based on M-estimation is used and the tap weight vector w(n+1) of the adaptive filter at next moment n+1 is calculated and equal to w(n)+mu P(n)(UT(n)P(n)+delta IK)-1 psi [E(n)]; E, n is set to be n+1, and the steps B, C and D are repeated until a call is ended. The method has a good cancellation effect on an acoustic echo of a communication system and is high in convergence speed and small in steady-state error.

The present invention discloses a gain self-adjustment type supercoiling slip form control method for an electro-hydraulic positioning servo system. By utilizing the information of an existing system model, a model-based feed-forward control law is led into the control algorithm of a traditional supercoiling slip form, so that the system servo accuracy is improved. The gain of a controller is updated in real time based on the self-adapting rule. In this way, the exact boundary of the system modeling nondeterminacy is not required to be apriori known. The conservative property due to the artificially preset control gain related to the above boundary in the conventional algorithm can be avoided. Based on the Lyapunov stability theory, the global stability of the closed-loop system is proved. The tracking error of the system asymptotically converges to be in an arbitrarily small range near to zero within the finite period of time. Meanwhile, the convergence speed and the boundary of the steady-state error can be adjusted through parameters.

The invention discloses a nonlinear multi-time-scale delay system modeling and control method and belongs to the technical field of controlling of complex systems. The method is based on the UDTTDFSPM and combined with a spectral norm and linear matrix inequality method, a robust combination controller is designed for controlled NMTSTDSs, and high-precision and stable control of the NMTSTDSs is achieved. According to a dynamic model of the NMTSTDSs, an uncertainty continuous time delay obscurity singular perturbation model of the NMTSTDSs is set up, a proper sampling period is selected, a zero-order holder method is adopted to perform discretization on the obtained continuous model, and the UDTTDFSPM of the NMTSTDSs is obtained. The robust combination controller is designed on the basis and is composed of an obscurity slow state feedback controller and an output integrator. The nonlinear multi-time-scale delay system modeling and control method has the advantage of solving the problem of steady-state errors which are caused by system external disturbance and the fast modality of the NMTSTDSs and cannot be solved by an existing modeling and control method, and the control performance of the NMTSTDSs is greatly improved. The nonlinear multi-time-scale delay system modeling and control method is used for controlling the simulation result of postures of a CE150 helicopter, and validity of the method can be shown.

The invention discloses a large power transformer self-adaptive active noise reduction control method. The method comprises the steps that a sensor collects primary noise as a reference signal and transmits the reference signal to a self-adaptive controller, and the self-adaptive controller outputs, according to the reference signal, a control signal to be used as a secondary signal so as to drive a loudspeaker to give out secondary noise; a primary sound field established by the noise made by a power transformer and a secondary sound field established by secondary noise made by the loudspeaker overlap, and an error sensor collects the overlapped sound pressure and forms an error signal; and the self-adaptive controller receives the error signal, and then adjusts, according to a preset objective function, the phase and amplitude of the secondary signal by use of a least mean square (LMS) algorithm for converging coefficient variation till the error signal satisfies the objective function and achieves a stable state. Through adoption of the method, while the steady state error performance is guaranteed, the converging speed of the algorithm is improved, and the noise reduction effect can be improved; and the initial value of the convergence coefficient can be selected more freely.

The invention discloses a permanent magnet synchronous motor fault-tolerant control device based on composite speed estimated rotating speed. After rotating speed omega 2 obtained by estimation through a model reference adaptive method (MRAS) and rotating speed omega 3 obtained by estimation through a high-frequency injection method are subjected to weighted processing, the estimated rotating speed is obtained; prior probabilities obtained based on a maximum likelihood estimation algorithm are inputted into a fault-tolerant control module based on posterior probability to obtain motor vector-controlled feedback rotating speed, accordingly, the goal of improving the dynamic performance of a system is realized, and meanwhile, the effect of steady-state error caused by the method is also reduced.

The invention discloses an adaptive beamforming method based on a convex combination. The method mainly comprises the following steps: an array antenna receives a signal, a least square adaptive filter and a variable step size adaptive filter are constructed, the weight updating formulas of two adaptive filters are subjected to convex combination to obtain the weight of a combined filter, the received signal is inputted to obtain a best weight vector through a convex combination filter, and the best weight vector and a scanning vector are subjected to multiplying to obtain an output signal of the antenna. The method has the advantages of fast convergence speed and small steady-state error, and the mobile communication has the advantages of high signal to noise ratio and good stability.

The invention discloses a variable-step LMS adaptive filtering method. The variable-step LMS adaptive filtering method comprises the following steps that (1) input signals are generated by means of a two-order AR model; (2) the products of input signals generated at all moments and the corresponding two-order prediction coefficients of a two-order linear prediction filter are added, so that output signals at the moments are obtained; (3) the differences between the input signals and the output signals are obtained, so that an error value is obtained; (4) the product of the error value, a step value and the input signals is taken as the two-order prediction coefficient of the two-order linear prediction filter with the updated transient variation; (5) the steps from the step (2) to the step (4) are iterated, so that w [1] (n) and w [2] (n) are made to converge, and an output signal is what is needed. According to the variable-step LMS adaptive filtering method, both the errors with the index being first power and errors with the index being second power are considered, the rate is convergence is maintained, and better steady state errors are obtained.

The invention discloses a sparse system identification method of variable step size lp norm LMS algorithm. The convergence of the algorithm is analyzed. The square root of the error generated in the iterative process is introduced into the step size control, and the normal number Vth is introduced to balance the convergence rate and steady-state error of the system. The step size of the system canbe adjusted effectively in real-time during the iterative process. In order to mine the sparsity of unknown channel, we introduce the lp norm into the cost function, and the algorithm can identify the sparse system accurately On the basis of keeping the excellent convergence rate and steady-state performance of the traditional LMS algorithm, the algorithm further improves the convergence rate andestimation accuracy of the system. Several new sparse adaptive algorithms are compared in experimental simulation, and the superiority of the proposed algorithm is verified by theory and experiment.

The invention provides an engine noise control method based on an FXLMS algorithm aiming at the problem of in-vehicle noise caused by an engine air inlet system, belonging to the field of noise control. The method comprises the following steps: S1, establishing a main control system model of engine intake noise by using an FXLMS algorithm, and constructing a reference signal x (k) of the main control system model by using the rotating speed of the engine; S2, establishing an off-line identification structure, identifying a secondary channel transfer function H2(z) in an active control system model, and providing an identification result to the active control system model; and S3, controlling the engine noise by using the identified active noise control system model. In addition, an improved variable step length algorithm is proposed. The algorithm adds the parameter gamma to the step length of the normalized algorithm and replaces beta in the sine variable step length to adjust the amplitude range of the step length. The algorithm not only has the advantages of fast convergence and small steady-state error of the sine variable step length algorithm, but also has the characteristicsthat the normalized algorithm is suitable for a time-varying reference signal, and the parameter is easy to select.

The invention relates to a repetitive controller of a position servo system. Reference signals with symmetrical periods are generated in a given link; a cycle feedback link is constructed; an ideal error dynamic state is formed based on the discrete time unit vector serialized attraction law; according to an error dynamic equation, a signal conversion mould is constructed, and an output signal of the signal conversion mould is applied to correction of the repetitive controller; and a signal obtained through the computation of a current controller is taken as input of a servo object. A specific controller parameter setting operation can be carried out according to indexes of convergence performance of a representation system, and a monotone decreasing area, an absolute attraction layer and a steady-state error band boundary of a representation trace error convergence process are provided. A closed-loop system can completely eliminate cyclically symmetric interference signals and realize that the position servo system follows the change of reference signals. The invention provides a cyclically repetitive controller capable of remarkably reducing the occupied space of a memory, effectively restraining the symmetric interference and improving the control precision.

The invention provides a feedback control method for the fuzzy time delay state of uncertainty time-delay two-time scale systems (UTDNTTSSs), and belongs to the technical field of high-precision control of complex systems. According to the method, based on an uncertainty standard disperse fuzzy singular perturbation model, a fuzzy time-delay state feedback controller is designed, and high-precision control over the complex UTDNTTSSs is achieved. Fuzzy logic, a singular perturbation technology and a time delay and uncertainty system theory are fused, the uncertainty standard disperse fuzzy singular perturbation model of the controlled UTDNTTSSs is established, combining with the fuzzy logic and a time-delay system theory, the fuzzy time-delay state feedback controller is designed, a spectral norm and LMIs method is adopted, it is deduced that sufficient conditions exist in the controller, high-precision control simulation is conducted through a CE150 helicopter attitude control system, and the specific implementation process and the effectiveness of the method are shown. The feedback control method for the fuzzy time delay state of the UTDNTTSSs has the advantages of solving the problem that in the existing modeling and control method of the UTDNTTSSs, steady state errors caused by time delay, quick modality and parameter perturbation can not be removed, and the control performance of the UTDNTTSSs is greatly improved.

The invention discloses a tracked unmanned vehicle trace tracking controller design method based on a kinematic model, and belongs to the technical field of vehicle control. The method includes the steps: firstly, building a state-space equation according to the kinematic model of a slip tracked vehicle; secondly, performing standard quadratic transformation according to a set target function; finally, calculating a new control sequence through the target function optimization process by a system in a next control period T, and repeatedly performing rolling optimization to realize trace tracking control. According to the method, a built controller has good tracking capacity for continuous and discrete point paths, particularly, running speed is stabilized near expected speed in the low-speed tracking process, linear tracking steady-state errors approach to 0, and running traces are smooth.