36results about How to "Good for engineering practice" patented technology

The invention relates to a method used for balancing three phases of direct current side voltages of a chain power regulating device, and belongs to the technical field of the control of power electronic devices. The method comprises the following steps of: acquiring direct current side voltages of each H-bridge unit in the three phases of a chain power regulating system; filtering ripples from the direct current side voltages; taking the direct current side voltages of which the ripples are filtered as feedback signals; calculating an average value of the three phases of the direct current side voltages based on the direct current side voltages; taking difference values between the three phases of the direct current side voltages and the average value as command signals; calculating an amplitude value and a phase angle of a negative sequence voltage according to the difference values by utilizing corresponding formulae; obtaining a required negative sequence according to an electric angle of a power supply voltage at a device grid place; and after the negative sequence voltage is superposed to an output voltage command used for power control in the device, driving the device to output an alternating current voltage so as to realize the balance control of the three phases of the direct current side voltages. The method of the invention has the characteristics of software implementation, simple algorithm, obvious effect and contribution to engineering application.

The invention discloses a method for realizing the five-freedom-degree alternating current active magnetic bearing displacement self detection by utilizing a mixed kernel function support vector machine displacement predicating model. According to the method, magnetic bearing control current is used as an input sample, radial and axial displacement is used as an output sample, the sample data is collected, a mixed kernel function is selected, the performance parameters of the support vector machine are optimized through a particle swarm algorithm, the training sample and the performance parameters are utilized for training the least square support vector machine, and a non-linear predicting model is built. The predicting model is connected with a linear closed loop controller before being connected to a five-freedom-degree alternating current active magnetic bearing in series, the magnetic bearing displacement closed loop control is formed with a first and second expansion current hysteresis three-phase power inverter and a switch power amplifier, the self detection of a five-freedom-degree alternating current active magnetic bearing displacement-free sensor is realized, the cost of a magnetic bearing system is reduced, and the dynamic property of the system is improved.

The invention provides a networking radar station distribution method based on particle mechanism immune population search. The method comprises the steps that a deceived probability model and a detection range model of networking radar under deceptive interference are established; a joint optimization objective function is established, and constraint conditions of the joint optimization objective function are determined; key parameters of a networking radar system and basic parameters of search teams are initialized, and the iteration number of the particle mechanism immune population search is determined; a fitness function is determined, and the best positions of single searchers and the best positions of search teams are initialized; a vaccine is prepared by using a popularization searching method; the positions of the searchers are updated, and the vaccine is inoculated to the search teams; immune selection is conducted on the search teams through elite selection and annealing selection, and the best positions are updated; by using a population searching method, premature convergent search teams are disturbed; whether the termination standard is met or not is judged. By adopting the method, optimal radar station distribution positions can be rapidly and accurately found under the situation that trapping in local optimum does not occur.

The invention discloses a five-degree-of-freedom magnetic levitation electric spindle rotor displacement self-detection system and method. The system is composed of a fuzzy support vector machine displacement prediction module, two linear closed-loop controllers and two force / current converters. The fuzzy support vector machine displacement prediction module is composed of four fuzzy support vector machine radial displacement prediction modules and a fuzzy support vector machine axial displacement prediction module. Each of the radial displacement prediction module and the axial displacement prediction module is composed of a training sample set module, a data preprocessing module, a fuzzy data module, an optimal performance parameter determination module and a fuzzy support vector machinetraining module. The fuzzification data module fuzzifies the training sample set by using a fuzzy membership function; the optimal performance parameter determination module optimizes a penalty parameter and a kernel width by using a simplified particle swarm optimization algorithm, and obtains a group of penalty parameter and kernel width with the best performance index; and the system structureis simplified, and the control performance of the magnetic bearing is improved.

The invention discloses an optimized power flow calculation method based on a multi-energy coupling model. The method comprises the following steps of establishing a multi-energy coupling model covering a power grid model, a heat supply network model and a cold network model based on CIM standard model expansion; determining optimal operation conditions of the electric energy equipment, the heat energy equipment and the cold energy equipment under different operation scheme modes to serve as input for optimizing load flow calculation; and determining the output of each source end device and the energy flow distribution of each energy network through the optimized power flow calculation. According to the method, the multi-energy complementary energy internet model is constructed, complementation of different energy sources is achieved through modeling of the multi-energy coupling equipment, and the method is easy and convenient to calculate, high in operability and high in practical application value.

The invention discloses a D8PSK coherent demodulation method and system, and the method comprises the steps: enabling a band-pass filter to receive a sampling modulation signal sent by AD sampling, and carrying out the band-pass filtering; processing the two paths of output signals of the band-pass filter to obtain baseband signals of an in-phase path and an orthogonal path; processing the baseband signals of the in-phase path and the orthogonal path to obtain two orthogonal paths of values of the optimal judgment sampling point of each symbol; feeding the two orthogonal paths of values of theoptimal judgment sampling point into a differential demodulation unit, a phase-locked loop unit, a frequency offset estimation unit and a frame synchronization unit at the same time; sending the differential decomposition modulation value is sent to a parallel-serial conversion unit, converting parallel input is converted into serial output, and acquiring a final demodulation sequence is obtained. A ; according to the method, a Gardner-based multi-level code element synchronization algorithm and a D8PSK difference decomposition modulation feedback-based phase synchronization algorithm are provided, so that the calculated amount is reduced to a great extent, and the engineering practice is facilitated.

The invention discloses a fuzzy control method of a direct current transmission converter based on command filtering. A fuzzy logic system is employed to approach unknown nonlinear terms in a power grid side converter system of a voltage source type direct current transmission converter system. A command filtering technology is introduced to solve the inevitable problem of 'calculation explosion'in the back-stepping control technology, the error of the filter is reduced by introducing a filtering compensation mechanism, and the command filtering technology has good inhibition effect on higherharmonics; the problems of unknown system parameters and uncertain disturbance intervention can be solved by introducing a self-adaptive control technology; under the control method of the invention,only one self-adaptive parameter exists in the controller, thereby reducing the on-line calculation burden and facilitating engineering practice. Simulation results show that the method can achieve quick and stable response to power and can achieve control of the power grid side converter.

The invention discloses an optimal design method for a conjugate heat transfer radiator with a cross-section runner. The method comprises the following steps: determining inlet and outlet positions, geometric dimensions and system boundary parameters of the conjugate heat transfer radiator; adopting a B spline curve function to simulate a runner track; determining the cross-section runner by usinga Bernstein function, and providing four degrees of freedom on a two-dimensional level; using a Bernstein function to represent a rotation angle, and providing different visual angles to analyze heatdissipation performance; establishing a shape optimization model by taking the coefficient of the embedded Bernstein function as a design variable, taking the minimum average temperature of an important plane as a target function and taking space size constraints; adopting a linear approximation constraint optimization algorithm COBYLA to optimize runner distribution, and normalizing design variables to improve optimization stability. The influence of the geometric dimension on the heat dissipation performance of the conjugate heat transfer radiator is further released, the temperature distribution of an important plane is improved, and the invention has important significance for guiding the design of the conjugate heat transfer radiator of electronic equipment.

The invention discloses a three-degree-of-freedom six-pole hybrid magnetic bearing rotor displacement self-detection system and method. The three-degree-of-freedom six-pole hybrid magnetic bearing rotor displacement self-detection system is composed of a fuzzy support vector machine displacement prediction module, a linear closed-loop controller and a force / current conversion module which are sequentially connected in series at the output end and the input end of a composite controlled object; each of two fuzzy support vector machine radial displacement prediction modules and a fuzzy support vector machine axial displacement prediction module is composed of a training sample set module, a data preprocessing module, a fuzzy data module, an optimal performance parameter determination moduleand a fuzzy support vector machine module, wherein the fuzzy data module assigns different membership values to samples with different importance degrees; the fuzzy membership values are calculated byadopting a kernel fuzzy clustering algorithm; the optimal penalty parameter and the core width are determined by the optimal performance parameter determination module by adopting a simplified particle swarm optimization algorithm; and a fuzzy support vector machine training module calculates the predicted displacement, the axial dimension of the magnetic bearing is reduced, and the dynamic performance of the system is improved.

The invention relates to a method for designing a crowbar resistor for passing through the low voltage of a double-fed type wind generator system, belonging to the technical field of wind power generation and comprising the following steps: firstly, acquiring the rotor turns ratio, the rotor resistance, the rotor rated current and the rotor current upper limit of a double-fed generator of the wind generator system; computing current overload multiples according to the rotor rated current and the rotor current upper limit; acquiring the DC bus voltage of the wind generator system; computing a per-unit parameter kc of the crowbar resistor according to the DC bus voltage, the current overload multiples, the rotor rated current and the rotor resistance; obtaining a modified per-unit parameter kc after properly increasing the per-unit parameter kc; and finally, designing the resistance value of the crowbar resistor to be Rc=kcRr. The method designs the crowbar resistor according to a principle of the LVRT process of a DFIG system, adopts the clamping effect of a DC bus in the LVRT process, ensures the LVRT property while having less current and ensures the safety of a fly-wheel diode of a rotor current transformer.

The invention relates to a multi-component system state opportunity maintenance optimization method. When an equipment maintenance strategy is formulated, the current state of the equipment is considered, and the future degradation trend and failure probability of the equipment are also considered. Only if the future degradation trend of the equipment is accurately known, the maintenance strategycan be better formulated. Thus, multiple prediction algorithms are compared, an equipment degradation prediction and residual life prediction model for a single individual is established on the basisof analyzing a state monitoring signal of the equipment, and an opportunity state maintenance model of the multi-component equipment in a long task period is established by considering the structure of the system and the length of the task period. According to the invention, advanced signal acquisition technology and signal processing technology are used, detection and real-time prediction of thesystem are realized, and the state-based maintenance theory and method of the equipment opportunity are expanded.

The invention discloses a method for evaluating the influence of direct-current power grid topology on fault current. The method comprises the steps that firstly, an equivalent circuit of a grounding mode of a metal return wire and a ground return wire is established, and a three-dimensional mesh circuit diagram decoupling method is provided, so that the equivalent circuit is planarized; an improved high-frequency equivalent model is provided, fault current calculation methods are deduced for a radial network and a ring network respectively, the theory is popularized to an n-end network, and then the influence of topological parameters and structures on fault currents is analyzed; an evaluation index k of the influence of the topology on the fault current is provided, and the influence of the initial fault current level of the power grid topology can be effectively evaluated; the k value determines which converter stations mainly come from in the initial stage of the single-pole short-circuit fault current of the direct-current power grid. According to the evaluation method provided by the invention, tedious calculation is avoided, and the influence of topology on the fault current can be directly and quickly evaluated.

The invention discloses a buffeting-free sliding mode control method of a piezoelectric driving micro-positioning platform, and belongs to the field of precision motion control. The invention aims toprovide a buffeting-free sliding mode control method for a piezoelectric driving micro-positioning platform, which realizes platform precision positioning control by adopting a particle swarm-based constrained generalized prediction algorithm. The method comprises the steps: establishing a Duhem-based piezoelectric driving micro-positioning platform system model with unknown disturbance, and deriving a piezoelectric driving micro-positioning platform system state relation equation according to the system model; designing a buffeting-free equivalent sliding mode controller based on a disturbance estimator to obtain a control signal, and controlling a system state relation equation of the piezoelectric driving micro-positioning platform, thereby realizing high-precision positioning control of the piezoelectric driving micro-positioning platform. According to the method, the particle swarm optimization algorithm is used for replacing a rolling optimization process in generalized predictive control to process input constraints and input change rate constraints, precise positioning control of the piezoelectric ceramic micro-positioning platform is achieved, the method can be extended tosolve more optimization problems, and the problems in more fields are solved.

The invention discloses a three-degree-of-freedom hybrid magnetic bearing rotor displacement self-detection method. The invention belongs to the field of high-speed and ultra-high-speed motor transmission. The invention relates to a method for realizing three-degree-of-freedom alternating-current and direct-current hybrid magnetic bearing displacement self-detection by utilizing a hybrid kernel function support vector machine displacement prediction model. A magnetic bearing control current is used as an input sample; radial and axial displacements are output samples; sample data are collected, hybrid kernel functions are selected, performance parameters of the support vector machine are optimized through a particle swarm algorithm; a least square support vector machine is trained by utilizing the training sample and the performance parameters; a nonlinear prediction model is established, the prediction model is connected in front of a three-degree-of-freedom alternating-current and direct-current hybrid magnetic bearing in series and connected with a linear closed-loop controller, an expanded current hysteresis three-phase power inverter and a switch power amplifier jointly form magnetic bearing displacement closed-loop control, and displacement-sensor-free self-detection of the three-degree-of-freedom alternating-current hybrid magnetic bearing is achieved.

The invention discloses a digital regression model modeling method for a temperature-induced deflection monitoring reference value of a main beam of a cable-stayed bridge. The digital regression model modeling method comprises the following steps: acquiring temperature characteristic time sequence data and temperature-induced deflection time sequence data; carrying out normalization processing on the data, and establishing a training set and a test set; building a digital regression model driven by the long and short term memory neural network, wherein the number of layers of the model is two; and finally, checking the effectiveness of the digital regression model. According to the method, the mechanical mechanism and the nonlinear performance of the deep learning technology are combined, the established neural network has interpretability, implementation is occultable, and the high-precision cable-stayed bridge temperature-induced deflection reference value can be obtained.

The invention discloses a pile top stiffness adjustment device based on a variable-strength supporting material, which comprises: a cover plate and a cylinder body, the cylinder body is in the structural form of an upper part opening and a lower part sealing, and a variable-strength metal supporting material is arranged in the cylinder body; The cover plate is arranged on the cylinder body and is in contact with the upper end of the variable-strength metal support material; the rigidity of the variable-strength metal support material is greater than that of the side wall of the cylinder body. The invention effectively utilizes the appearance parameters of the variable-strength metal support material to change its own compression performance, and overcomes the fact that the volume of the support material itself cannot be changed in the existing pile top stiffness adjustment device, and the vertical compression can only be caused by the crushing or discharge of the support material. Disadvantages of displacement, high adjustment accuracy, stable operation, simple preparation process, low manufacturing cost, convenient installation, the load-displacement curve of the stiffness adjustment device under the action of the upper load has a significant linear change characteristic, without any fluctuation phenomenon, there is It is beneficial to further promote the engineering practice of pile-raft foundation with controllable stiffness.

The invention provides a magnetic field shielding system which comprises two first-level superconducting coils and two second-level superconducting coils. The first-level superconducting coils and the second-level superconducting coils are coaxially arranged around a center symmetry axis. The size of the first-level superconducting coils is different from that of the two second-level superconducting coils. A first coil group is formed by one first-level superconducting coil and one second-level superconducting coil. A second coil group is formed by the other first-level superconducting coil and the other second-level superconducting coil. The first coil group and the second coil group are insulated and are in mirror symmetrical arrangement. A closed loop is formed by the first-level superconducting coil and the second-level superconducting coil in each of the coil groups. The invention further provides a magnetic field shielding device. According to the system, the technological realization line is simple, and the engineering practice is facilitated.

The invention discloses a fuzzy control method of a direct current transmission converter based on command filtering. A fuzzy logic system is employed to approach unknown nonlinear terms in a power grid side converter system of a voltage source type direct current transmission converter system. A command filtering technology is introduced to solve the inevitable problem of 'calculation explosion'in the back-stepping control technology, the error of the filter is reduced by introducing a filtering compensation mechanism, and the command filtering technology has good inhibition effect on higherharmonics; the problems of unknown system parameters and uncertain disturbance intervention can be solved by introducing a self-adaptive control technology; under the control method of the invention,only one self-adaptive parameter exists in the controller, thereby reducing the on-line calculation burden and facilitating engineering practice. Simulation results show that the method can achieve quick and stable response to power and can achieve control of the power grid side converter.

The invention, which belongs to the field of the anti-interference technology of the radar, discloses an optimized station distribution method for a netted radar unit under deceptive jamming. The method comprises: a deceived probability of a netted radar is calculated; a target function of a minimized deceived probability is constructed; coverage ranges of all node radars in the netted radar unit are calculated and a target function of a maximized coverage range is constructed; according to the target function of the minimized deceived probability and the target function of the maximized coverage range, a combined optimized target function is established; a constraint condition of station distribution of the netted radar unit is determined; on the basis of the constraint condition of station distribution of the netted radar unit and the combined optimized target function, an optimization formula of station distribution of the netted radar unit is constructed under deceptive jamming; and station distribution positions of all node radars in the netted radar unit are obtained based on the optimization formula of the station distribution of the netted radar unit under deceptive jamming. Therefore, the radar system resources are saved and precise and effective inhibition of the deceptive jamming can be realized.

The invention discloses a method for judging and controlling the dynamic stability of flexible direct current transmission. The judgment method includes the following steps: unlocking the converter station of the flexible direct current transmission system, allowing the flexible direct current transmission system to operate in a non-island control mode; extracting the flexible direct current The corresponding parameters of the power transmission system, the parameters include the effective value of the AC system voltage U t0 , flexible DC output reactive power Q vsc0 , the gain k of the phase-locked loop PLL p and the proportional-integral time constant k of the phase-locked loop PLL i ; Calculate the short circuit ratio SCR, and calculate U t0 , Q vsc0 The per unit value of ; calculate the key stability component; check the sign of the key stability component and determine the stability of the HVDC system. The method of the invention only needs to simply calculate the value of the key stable component, and judge the stability of the system through the sign of the value, which is simple and easy to implement, and is beneficial to engineering practice.

The invention provides a voltage sag detection method for a cascade type electric energy quality comprehensive treatment device. The method comprises the following steps: 1, acquiring a three-phase phase voltage instantaneous value signal of a power grid; 2, calculating a power grid voltage phase angle and a voltage component of the three-phase phase voltage of the power grid in an alpha-beta rotating coordinate system according to the instantaneous value signal of the three-phase phase voltage of the power grid; 3, calculating a voltage component under a positive and negative sequence dq coordinate system according to a result obtained by calculation in the step 1, and obtaining positive and negative sequence fundamental wave components through positive and negative sequence decoupling and high-frequency filtering; 4, according to the positive sequence fundamental component and the negative sequence fundamental component, calculating negative sequence fundamental component angle characteristic quantity and three-phase power grid voltage positive sequence fundamental component amplitude modulus length, and obtaining a characteristic value based on a voltage sag voltage threshold value; and 5, according to the negative sequence fundamental component angle characteristic quantity, the three-phase power grid voltage positive sequence fundamental component amplitude modulus length and the characteristic value, determining the power grid voltage sag and the type thereof. The method can be realized by software, the algorithm is simple, the effect is obvious, and engineering application is facilitated.

The invention discloses a receiving-end cascaded hybrid direct current coordinated control method based on dynamic limiting, comprising the following steps: under the master-slave control mode adopted by the MMC, the overall UI characteristic curve of the receiving-end cascaded hybrid direct current transmission system is clarified ; The dynamic limiting link is set in the fixed power flexible converter station of cascaded hybrid direct current transmission at the receiving end. The method of the invention can release the reactive power support potential of the flexible DC to the AC system to enhance the voltage stability of the AC system when the receiving end system fails, and can automatically limit the active power output of the constant power station to avoid the flexibility of the constant DC voltage. The finishing and inverter mode of the converter station is changed, which improves the system stability in terms of active frequency and reactive voltage.

The invention discloses an open-type magnetic field shielding device capable of adjusting at full frequency band, and belongs to the technical field of electromagnetic compatibility. The magnetic field shielding device comprise a magnetic field searching coil, a magnetic field detection oil, a driving circuit, a magnetic field adjustment coil and a corresponding matched sample table, wherein the magnetic field detection coil is used for monitoring change of an environmental magnetic field, the magnetic field adjustment coil is driven to offset with an external magnetic field by the driving circuit after a power is amplified, the magnetic field searching coil is placed right above the device, the sample table is placed in the center of the magnetic field adjustment coil, the magnetic fielddetection coil is connected with a magnetic field detection probe and is placed on the sample table, the driving circuit is placed at an outer side of the magnetic field adjustment coil, and a shielded magnetic field is arranged above the driving circuit. The magnetic field shielding device capable of adjusting at full frequency band is more beneficial for engineering practice.

The invention provides a magnetic field shielding system based on a closed superconducting coil group, which includes a first-level superconducting coil and a second-level superconducting coil arranged coaxially and coplanarly around the same central axis of symmetry, the first-level superconducting The coil is connected in series with the second-level superconducting coil to form a closed loop, and a shimming area is formed inside the second-level superconducting coil to shield the external magnetic field. The present invention further provides a magnetic field shielding device. The process of the magnetic field shielding system in the invention has a simple realization route and is beneficial to engineering practice.

The invention relates to a method used for balancing three phases of direct current side voltages of a chain power regulating device, and belongs to the technical field of the control of power electronic devices. The method comprises the following steps of: acquiring direct current side voltages of each H-bridge unit in the three phases of a chain power regulating system; filtering ripples from the direct current side voltages; taking the direct current side voltages of which the ripples are filtered as feedback signals; calculating an average value of the three phases of the direct current side voltages based on the direct current side voltages; taking difference values between the three phases of the direct current side voltages and the average value as command signals; calculating an amplitude value and a phase angle of a negative sequence voltage according to the difference values by utilizing corresponding formulae; obtaining a required negative sequence according to an electric angle of a power supply voltage at a device grid place; and after the negative sequence voltage is superposed to an output voltage command used for power control in the device, driving the device to output an alternating current voltage so as to realize the balance control of the three phases of the direct current side voltages. The method of the invention has the characteristics of software implementation, simple algorithm, obvious effect and contribution to engineering application.

The invention discloses a coordinated control method for improving the stability of a cascaded hybrid direct current transmission system. When a fault occurs, according to the transmission power of the line, the output power of the LCC on the inverter side, and the steady-state output power of the constant direct current voltage MMC, the multi-drop point MMC is controlled. The active power command value is regulated to avoid the conversion of the constant DC voltage station from inverter to rectifier, and to prevent the phenomenon of large-scale transfer of power on the AC side of the receiving end. At the same time, after the fault is cleared, the problem of large fluctuations in the system recovery process can still be alleviated, so that the system can quickly and smoothly return to the rated operating state. The invention can realize the smooth transition of the system under typical faults of AC and DC, and improve the stability of the DC receiving end system.

The invention discloses a neural network output feedback self-adaptive robust control method based on a launch platform. The steps of the method are as follows: firstly, a mathematical model of the launch platform is established, and secondly, a neural network state observer and a neural network state observer based on the neural network state observer are designed. Network output feedback adaptive robust controller; Finally, the stability of the neural network state observer and neural network output feedback adaptive robust controller is proved by using Lyapunov stability theory. The invention solves the problem that the real value of the state quantity in the motor servo system of the launch platform is difficult to obtain.

The invention discloses a flexible DC power transmission oscillation frequency prediction and control method under a non-island control mode. The prediction method comprises the following steps: unlocking a convertor station of a flexible DC power transmission system, and running the flexible DC power transmission system in the non-island control mode; extracting corresponding parameters of the flexible DC power transmission system, wherein the corresponding parameters comprise an AC system voltage effective value UtO, a gain kp of the phase-locked loop PLL and the proportion integral time constant ki; taking the AC system voltage as a reference value, computing the prediction oscillation frequency; and checking whether the prediction oscillation frequency is a non-zero real number; if theprediction oscillation parameter is the non-zero real number, regarding that the flexible DC power transmission system is unstable, the flexible DC power transmission system has the oscillation at the frequency band and cannot be put into the flexile DC power transmission; if the virtual number is equal to zero, regarding that the flexible DC power transmission system is stable, the frequency band oscillation mode is inexistent, and the system can be put into the flexible DC power transmission. The corresponding oscillation frequency can be computed through simple parameter, the prediction issimple and practicable, and in favor of engineering practice.