288results about How to "Physical concepts are clear" patented technology

The invention relates to a partial-compensation aspherical reflector surface shape detection method, which comprises the following steps of demarcating partial-compensation elements to obtain demarcated phase distribution Wb; using the demarcated phase distribution Wb, sphere theory wavefront Wq and aspherical theory wavefront Wf to obtain phase distribution Wy of digital virtual sample plates; measuring an aspherical reflector surface to be measured to obtain phase distribution Wa; and reducing the phase distribution Wy from the measured phase distribution Wa to achieve surface shape error distribution Wm of the aspherical surface. The partial-compensation aspherical reflector surface shape detection method can accurately measure optical aspherical surface shapes by using a single partial-compensation element, thereby reducing design difficulty of a compensator, simplifying structure of the compensator and being clear in physical definition, simple in data processing and arithmetical operation, simple and practical in experimental operation, low in detection cost and short in test time.

The invention discloses a micro-grid short-term load forecasting method based on the EMD-KELM-EKF, and belongs to the technical field of intelligent power grids. The method includes the steps of firstly, preprocessing micro-grid history load data, enabling the preprocessed micro-grid history load data to serve as a training sample, and extracting the load attribute of the training sample; secondly, determining a combined forecasting model based on the EMD-KELM-EKF and parameter initial values of the combined forecasting model; thirdly, optimally selecting parameters of the combined forecasting model through a particle swarm optimization algorithm; fourthly, substituting a test sample into the combined forecasting model based on the EMD-KELM-EKF with determined parameters to obtain a forecasting result. The method is clear in physical concept and thought, and provides the theoretical foundation for micro-grid short-term load forecasting, and calculation is easy and convenient; according to the method, by means of the implementation pattern of combining offline parameter optimization with online forecasting, the forecasting result is good in stability, and optimal dispatching can be easily conducted on micro-grids.

The invention relates to a crop evapotranspiration model-based intelligent drop irrigation control system and a method thereof. The drop irrigation system is arranged in a greenhouse and is characterized by comprising a data acquisition module, multiple A/D conversion modules connected with the data acquisition module, a controller (3), a D/A conversion module, a driving circuit and an execution mechanism, wherein the data acquisition module is used for acquiring a corresponding input signal, the signal output terminal of the data acquisition module is connected with the signal input terminal of a corresponding A/D conversion module, the signal output terminal of the A/D conversion module is connected with the signal input terminal of the controller (3), the controller (3) controls an output driving circuit connected with the controller, and the execution mechanism is operated by virtue of the driving circuit to realize irrigation. In the invention, the evapotranspiration is calculated and is indirectly taken as irrigation volume to carry out irrigation on a crop, and moisture required by the crop is supplemented more accurately; and the structure is simple, and the cost is low, thus the system and the method provided by the invention have high promotional value.

Aiming at a problem that an ip-iq algorithm cannot precisely acquire fundamental wave positive sequence active currents under the conditions of non-ideal power network voltages, the invention provides a method for detecting a harmonic wave and a reactive current based on spatial transformation of voltage vectors. The method comprises the steps of performing coordinate transformation on currents and voltages on an ip-iq algorithm channel to acquire phase information of three-phase fundamental wave positive sequence voltages; defining a p-q coordinate system; defining correct positive sequence active components and positive sequence reactive components by using the projection of a current vector on a voltage vector and a normal line thereof under the coordinate system; then accurately solving fundamental wave positive sequence active components, fundamental wave positive sequence reactive components, fundamental wave negative sequence active components and fundamental wave negative sequence reactive components in a load current by taking the correct positive sequence active components and the positive sequence reactive components as reference volumes and using an improved ip-iq algorithm; and popularizing the detection of the four fundamental wave current magnitudes into the detection of any sub-harmonic current magnitude to form a current detection system under the conditions of non-ideal voltages so as to provide reasonable reference instruction currents for various compensation requirements.

The invention relates to a method for detecting surface figures of a large-aperture off-axis convex aspheric mirror. The method comprises the following steps of: performing null interferometry on reference sub-aperture regions by using computer-generated holographic elements which correspond to surface figures of the reference sub-aperture regions of an aspheric mirror to be detected; performing null interferometry on off-axis sub-aperture regions by using computer-generated holographic elements which correspond to surface figures of the off-axis sub-aperture regions of the aspheric mirror to be detected: solving the distribution of full-aperture surface figures of the convex aspheric mirror to be detected; converting coordinates of all off-axis sub-apertures in an x-y-z coordinate system into coordinates below an X-Y-Z coordinate system and obtaining the distribution of full-aperture phases of the convex aspheric mirror to be detected by calculation; and removing system adjustment errors from the distribution of the full-aperture phases to obtain the error distribution of the full-aperture surface figures of the convex aspheric mirror to be detected. The invention has the advantages of simple data processing and mathematical operation, easy experiment operation, low detection cost and short testing time.

The invention relates to a D-axis and A-axis current vector composite controller of a permanent-magnet synchronous motor. The D-axis and A-axis current vector composite controller is characterized by comprising a position sensor, a speed measurement feedback link, a counter potential feed-forward compensator, a rotational speed closed-loop controller, an A-axis current composite controller, a D-axis current composite controller and a vector converter. By the D-axis and A-axis current vector composite controller, decoupling composite control is separately carried out on i<d> and i<q> under a dq coordinate, the speed regulation range is wide, phase shift of a phase current closed-loop control structure caused by limited bandwidth of the controller is prevented, and the D-axis and A-axis current vector composite controller has favorable performance in all ranges of speed regulation; through the adoption of a composite controls structure with combination of feed-forward and feedback, the dynamic characteristic is improved, the feedback control gain is reduced, and the gain margin of the system is improved; feed-forward is designed on the basis of the dynamic characteristic of an object, and D-axis and A-axis current vector composite controller is clear in physical concept, simple in structure and stable in working, and is easy to be implemented; and meanwhile, feedback control is introduced, the control precision is improved, and an error caused by model inaccuracy and disturbance is overcome.

The invention provides a Markov state space diagram method for evaluating the reliability of a converter transformer subsystem, which comprises the following steps: analyzing the structure, the operation characteristics, the state and the state interline transfer rate of the converter transformer subsystem, and setting up a Markov state space diagram of the converter transformer subsystem; utilizing a computer to solve the Markov state space diagram through a program; and obtaining and outputting the reliability index of the converter transformer subsystem. The method can fully analyze the structure and the operation characteristics of the converter transformer subsystem, which comprise two fault modes of a converter transformer, the wiring mode of the converter transformer subsystem, a component group operation stopping model and a converter transformer station single-side whole standby mode as well as the fault, the repair and the random transfer process of standby switching installation of the converter transformer subsystem; and by calculating the expected transfer number of borders traversing and surrounding the boundaries of merger states, merger state frequency indexes can be obtained, and the influence of the transfer frequency among the merger states to the frequency indexes can be eliminated, so that remarkable superiority exists during calculating the frequency indexes, and the calculating result is more accurate. The method is suitable for evaluating the reliability of the converter transformer subsystem in a high-voltage direct-current transmission system of single-twelve-pulse and double-twelve-pulse wiring.

The invention provides a method for measuring dynamic voltage stability margin index, while the dynamic voltage stability margin index is the margin to the voltage collapse point of a power system which load increase slowly in a certain speed; the dynamic voltage stability margin index considers that the system is affected by the dynamic components such as the on-load tap changer (ULTC) and the over excitation limit of engines. The method can calculate the dynamic margins of the system which load increases in various types such as single node, regional or full-network type, to provide a visual measurement presenting the distance between the prior operation point of the system and the voltage collapse point, while the distance and the dynamic margin have linear relationship. Therefore, the dynamic margin index has high practical values.

The invention relates to a method for recognizing grid topology based on a measurement spanning tree, belonging to the technical field of electric power system dispatching automation. The method comprises the steps of: firstly, generating a bus-branch model of a network and a tree structure, and calculating voltages and phase angles of nodes by layers; calculating active and passive powers of two ends of the branches according to impedance parameters of the branches; checking the calculating values and the measurement values, if having larger deviation, adding a bad mark on a corresponding network element, sequencing suspicious degrees of the bus and the branches according to the quantity of the bad marks; speculating switch brakes with telecommands possibly having errors and lines with operation states possibly having errors from the suspicious bus and the suspicious branches; and determining whether the deflection of the switch brakes is reasonable or not through judging whether the quantity of the bad marks in the network after the corresponding switch brake deflects is reduced or not. The method is used for recognizing topological errors without state estimation results and convergence problems, and has the advantages of higher calculating speed and wide application range compared with the algorithm using state estimation.

The present invention relates to a fluid-solid coupling computing method based on a fixed grid technology and belongs to the technical field of fluid-solid coupling simulation. The method comprises the following steps of: A, calling a grid dividing module which adopts two sets of grids including an overall physical area formed by fluid and solid and a solid area; B, calling a fluid field computing CFD module to update a fluid field state variable and simultaneously obtain a force applied to a solid boundary node by the fluid; C, calling a solid computing CSD module to update a solid state variable and simultaneously obtain displacement and speed of the solid boundary node; D, calling a result output module to output the solid state variable and the fluid field information to a file for use in post-processing; and E, judging whether to end computing. According to the fluid-solid coupling computing method, a movable grid module is successfully avoided, so that the computing resources for updating the grid are greatly saved; and the defect that the action force on a fluid-solid interface is hard to calculate accurately because of traditional complex inner grid updating and boundary grid control computing on the basis of movable grid technology can be overcome.

The invention relates to a gyro moment measuring device, which mainly comprises a force transducer, a gyro rotor, a gyro stator shaft component, a ball bearing, a gyro power supply slip ring, a gyro bracket, a gyro power supply battery, a signal slip ring of the force transducer, a frame rotating motor, a bracket for the frame rotating motor, a revolution stepping switch for the frame rotating motor, a transmission device, a display device, a base and a deep groove ball bearing. The gyro stator shaft component is connected with the gyro rotor through the ball bearing and is fixedly connected with the force transducer, the force transducer is fixedly connected with the gyro bracket which is connected with the base through a rotating shaft, an output rotating shaft of the frame rotating motor is connected with the transmission device which is engaged with a gear on the gyro bracket, and the bracket for the frame rotating motor and the display device are fixedly connected with the base. The gyro moment measuring device uses the force transducer to measure pressure, calculate gyro moment and display the gyro moment in the display device, and can intuitively learn gyro moment effect.

The invention provides an analysis method of a transmission line wind-ice coupling load line breakage effect. The analysis method includes the following steps that 1, geometric parameters and physical parameters of a transmission tower line system are determined, and a transmission tower line system analysis model is established; 2, icing loads of the transmission tower line system are determined; 3, a non-linear analysis method of a transmission tower line system reaction under the effect of the icing loads is established; 4, a wind load model in which the wire icing thickness changes is established; 5, a dynamic analysis method that a transmission wire is broken under the effect of wind-ice coupling loads is established, and the dynamic effect of transmission line icing line breakage is analyzed and calculated. According to the method, the coupling effect of the icing loads and wind loads is considered at the same time, the analysis formula is displayed and expressed, the calculation speed is high, the calculation amount is small, and the defects of existing traditional methods can be effectively overcome. The method is suitable for analysis and calculation of the icing line breakage effect of various transmission tower line systems with different spans and sags under the effect of the ice-wind coupling loads.

The invention discloses a method for suppressing sub-synchronous oscillation (SSR) based on a thyristor controlled reactor (TCR). In the method, the phase relationship of a TCR trigger angle alpha and electrical torque Te of a generator is measured through a time domain frequency scanning method, and based on the phase compensation principle, filtering, amplifying and phase compensation are respectively carried out on component of each comtorsional vibration mode of speed signal of the generator by utilizing a plurality of modes for controlling channels, thereby the TCR can provide positive electrical damping near each dangerous torsional vibration mode of the generator, and the purpose of suppressing sub-synchronous oscillation is achieved. The method has the advantages of definite physical conception and convenient engineering implement.

The invention belongs to the technical field of river numerical simulation, and provides a digital terrain generation method for a branchless river. The method comprises the following four steps: (1)acquiring basic data, (2) carrying out mesh generation of target river sections, (3) carrying out cross-section generalization and (4) generating a digital terrain. Based on the characteristic longitudinal control line and less measured cross-sectional topographic data, the method can solve the problems of high cost, long period and great difficulty in constructing river network model caused by the prior art that a large amount of terrain data covering a simulation area and evenly distributed are needed to ensure the truth and reasonableness of the grid interpolation result, and effectively reduces the generation difficulty of river digital terrain and the construction cost of river network model.

The present invention provides a rapid measuring method for installation error of a strapdown inertial system gyroscope based on a three-axle rotary table; the strapdown system is installed on a chassis of the three-axle table; sensing shafts of an Y gyroscope, a X gyroscope and a Z gyroscope are pointed at an inner frame, a middle frame and an outer frame of the rotary table, and the inner frame is pointed to the east, the middle frame is pointed to the north and the outer frame is pointed to the sky; the rotary table chooses the northeast direction to respectively adjust the angles of the inner frame, the middle frame and the outer frame to cause the Y gyroscope, the X gyroscope and the Z gyroscope to satisfy the output requirement to get the first to sixth installation errors of the gyroscope. The method separates the installation error from the standardizations of the gyroscope and avoids the influence caused by coupling each measuring parameter in the testing method for the standardizations of the gyroscope of the traditional speed experiments by directly and quickly measuring via the three-axle rotary table. Compared with the prior art, the method is simple and quick, has explicit physical conception, easy understanding and small calculation amount. Therefore, the method is a rapidly, directly and independently measuring method with higher precision.

The invention discloses a design method for a DC filter in a high voltage DC transmission project. The design method comprises the following steps of: (1) determining the main capacitance and tuning frequency of the filter according to the system conditions; (2) equalizing the three-tuning filter to 3 single-tuning filters, and calculating the parameters of each single-tuning filter on the restrictive conditions of the main capacitance and tuning frequency of the three-tuning filter; (3) acquiring the parameter of the three-tuning filter based on the parameters of single-tuning filters through an equivalence formula according to the principle of admittance consistency; and (4) performing performance computation for the configured filter, regulating the main capacitance or tuning frequencyof each single-tuning filter if requirements are not met, and then repeating the steps till the requirements are met. The design method is clear in physical concept, convenient in parameter adjustment and high in engineering application value, and can greatly improve the design efficiency of the DC filter.

The invention relates to a dynamic monitoring method for internal energy loss of a water turbine. The method decomposes the internal energy loss of the water turbine into four types: bulk loss, hydraulic loss of passageways, mechanical friction loss and impact loss and offers an expression of loss and a calibration method of corresponding loss coefficient; and then by defining the reduced parameters, the method converts the water head and flow rate in a water turbine model to the parameters of actual measurement in operation of a machine unit and further offers a method for calculating variousinternal energy losses inside the water turbine in real time by using the parameters of actual measurement in the machine unit. The method offers basis for the research based on internal energy lossproperty and the improvement of relevant problems in the operation of water turbines.

The invention provides an optimal configuration method of distributed generations (DG) based on a power moment algorithm and relates to a configuration method for accessing the DGs to a power distribution network, which is utilized to solve the problems that a uniform load distribution characteristic or a constant power factor load condition is considered only, or a configuration result is influenced easily by initial parameters, or a condition of random load distribution in an actual power distribution network is not considered, and existing methods are complicated in the prior art. The optimal configuration method of the DGs provided the invention is utilized to respectively define active second moment and active first moment with the beginning of the minimum target function of network loss, thus a power moment method for optimally configuring the DGs is put forward, which comprises the following steps: determining the installation positions of the DGs in accordance with the active second moment; determining active optimization of the DGs in accordance with the active first moment; and determining reactive optimization or compensated reactive capacity of the DGs in accordance with reactive first moment. The method can be also applied to determining the problems of real-time active output power and reactive output power of each DG in real-time scheduling.