95 results about "Characteristic equation" patented technology

A method for determining a fluid flow rate with a fluid control valve utilizes inherent characteristics of a particular valve in conjunction with easily measured parameters in order to determine a flow rate through the valve. A valve flow characteristic equation, a flow coefficient, and a rangeability for the valve are known and hardcoded into a chipset that controls the valve. A differential pressure transducer measures the pressure drop across the valve. A valve actuator controls the valve opening fraction. The differential pressure transducer and the valve actuator provide feedback signals to the chipset. The known and measured parameters are used to calculate an instantaneous valve characteristic and a fully-open flow rate for the valve. The instantaneous flow rate through the valve is then calculated from the instantaneous valve characteristic and the fully-open flow rate.

The invention relates to a double-fed grid-connected system subsynchronous oscillation analysis method by considering a frequency coupling effect. The method comprises the following steps of: firstly,inputting the fan parameter, the operation state and the grid-connected parameter of the doubly-fed grid-connected system; and establishing a doubly-fed fan external impedance analytical model basedon a harmonic linearization method. The method is mainly characterized in that the frequency coupling effect of output harmonic current of the doubly-fed fan under single-frequency harmonic voltage disturbance is considered, and meanwhile, according to two operating states of the doubly-fed fan, the external impedance analytical model of the fan is derived under different operating states; a polecriterion expression suitable for the characteristic equation of the doubly-fed grid-connected system is given in combination with grid-connected parameters; and finally, the subsynchronous oscillation stability of the target is judged system according to the calculated poles of the system characteristic equation. The subsynchronous oscillation mechanism of the doubly-fed grid-connected system isdisclosed quantitatively, and the subsynchronous oscillation stability of the target doubly-fed grid-connected system can be quantitatively analyzed.

The invention relates to a heat supply network waterway modeling method for comprehensive energy system scheduling, and belongs to the technical field of operation control of comprehensive energy systems. According to the method, a hydraulic analysis model and a power network model are unified, and a relationship between a hydraulic dynamic state and a hydraulic steady state is established. The method is based on characteristic equations of a heat distribution pipeline, a flow control valve and a booster pump. The method comprises: abstracting waterway element models such as water resistance,water inductance and a water pressure source, establishing hydraulic branch characteristics of a heat supply network based on the waterway elements, establishing hydraulic topology constraints of theheat supply network based on Kirchhoff-like voltage and current laws, and finally establishing a steady-state hydraulic network equation by combining the hydraulic branch characteristics and the hydraulic topology constraints. The method is clear in physical significance, covers various devices such as a heat distribution pipeline, a flow control valve and a booster pump, comprehensively considersheat supply network branch characteristics and topological constraints, is high in modeling method applicability, and facilitates unified scheduling of a heat heterogeneous energy flow system and anelectricity heterogeneous energy flow system.

The invention discloses a method for calculating short-circuit current of a power distribution network containing an inverter distributed power supply. The method comprises the following steps of: 1, establishing an output characteristic equation of the distributed power supply, a node admittance matrix of the network and a fault point boundary condition; step 2, on the basis of the step 1, cyclic calculation is carried out by using a linear iteration method; step 3, on the basis of the steps 1 and 2, performing second-order convergence iterative calculation based on a Newton-Raphson principle and a positive sequence augmented network node voltage equation, and calculating to obtain each node voltage and branch current of the positive sequence network; and 4, calculating node voltage and branch current of the negative-sequence and zero-sequence network by combining the fault point boundary condition in the step 1 based on the calculation result in the step 3, synthesizing fault node phase voltage and branch fault current of the power distribution network by using a symmetric component method, and outputting a result. A reference basis is provided for power distribution network fault positioning, fault diagnosis and the like through an accurate short circuit calculation result.

The invention discloses a method for judging the small-interference stability of a converter grid-connected system under polar coordinates. The method comprises the steps: acquiring an admittance model of a converter and a power grid under coordinates by linearly processing a dynamic equation of the converter grid-connected system, and then establishing an admittance model of the converter and anadmittance model of the power grid; performing coordinate transformation on the admittance model of the converter and the admittance model of the power grid under the dq coordinates to obtain a converter admittance model and a power grid admittance model under the polar coordinates; obtaining a single-input single-output closed-loop system model and a closed-loop characteristic equation, and performing judging by using a Nyquist curve according to the closed-loop characteristic equation or calculating the stability margin of the system according to the closed-loop characteristic equation to obtain a result whether the current control parameter of the converter can enable the converter to operate stably or not. According to the method, the stability margin of the converter grid-connected system can be effectively calculated, the influence of the control parameters of the converter on the stability of the grid-connected system is judged, and the instability problem caused by improper setting of the control parameters of the converter is avoided.

The invention belongs to the technical field of geometric modeling, and particularly relates to a geometric parametric modeling method and device for an aircraft fuselage frame structure. The method comprises the steps: intercepting a curve on the inner profile geometry and the outer profile geometry of a fuselage frame according to a frame position plane, and obtaining a first inner profile geometry curve and a first outer profile geometry curve; constructing a first characteristic equation of the inner shape surface and the outer shape surface, intercepting discrete point coordinates on thefirst inner shape surface geometric curve and the first outer shape surface geometric curve, and performing curve reconstruction according to the first characteristic equation to obtain a second innershape surface geometric curve and a second outer shape surface geometric curve; constructing a coefficient control equation, respectively adjusting the second inner surface geometric curve and the second outer surface geometric curve, and obtaining a contour curve of the fuselage frame according to the two adjusted curves; and constructing a second characteristic equation, intercepting nodes on the contour curve of the fuselage frame according to the second characteristic equation, and taking the nodes as positions for arranging frame reinforcing ribs.

The invention discloses a shale adsorption capacity prediction method based on an adsorption characteristic curve and a characteristic equation. The method comprises the steps of collecting an organicmatter shale sample for vacuumizing; collecting isothermal adsorption data of methane; calculating an adsorption potential and an excessive adsorption capacity; correcting the excessive adsorption capacity into an absolute adsorption capacity; performing nonlinear fitting on the absolute adsorption capacity and the adsorption potential to obtain an initial adsorption characteristic curve; obtaining an optimal fitting curve as an optimal adsorption characteristic curve, taking a fitting equation corresponding to the optimal adsorption characteristic curve as the characteristic equation, and rewriting the characteristic equation into a function of adsorption capacity and temperature and pressure by use of an adsorption potential theory; and acquiring the temperature and pressure of a reservoir stratum and related geological data, importing the temperature and pressure of the reservoir stratum and the related geological data into the function of adsorption capacity and temperature and pressure, and obtaining the organic matter shale adsorption capacity in the reservoir stratum through calculation. According to the shale adsorption capacity prediction method based on the adsorption characteristic curve and the characteristic equation, a model can further predict the adsorption gas content of the organic matter shale reservoir stratum, and the method has broad application value indetailed description of the gas content of the reservoir stratum.

The invention discloses an intelligent operation optimization method and system for a gas-fired boiler unit. The method comprises the following steps: S1, collecting original data of a gas-fired boiler unit in real time; S2, storing and managing the collected original data by utilizing database management software; S3, establishing a gas-fired boiler unit operation characteristic equation according to the original data; S4, establishing a gas-fired boiler unit optimization model according to the parameters of the gas-fired boiler operation characteristic equation; S5, obtaining an optimal solution of the gas-fired boiler unit optimization model through a coordinate rotation method; and S6, performing optimization adjustment according to the optimal solution result. According to the intelligent operation optimization method and system for a gas-fired boiler unit disclosed by the invention, through a big data mining technology, a coordinate rotation method and other intelligent optimization algorithms, valuable information is rapidly obtained from boiler unit production data, and the optimal operation value in actual production is found out to guide operation personnel in operation.Thus, theoretical support is provided for improving economic benefits of thermoelectric enterprises.

The invention discloses a method and apparatus for designing a fuel cell wide area ejector. The method comprises the following steps: obtaining fuel cell stack parameters and working conditions; establishing a steady-state characteristic equation of fuel cell ejector and the characteristic equation of ejecting fluid with water. The steady-state characteristic equation of fuel cell ejector and thecharacteristic equation of ejecting fluid with water are coupled into the mathematical model of fuel cell ejector. The available load range of the ejector is predicted by using the model, and the hydrogen ejection performance curve in the available load range of the ejector is obtained. The initial parameters are determined in order to optimize the nozzle diameter, mixing chamber diameter / nozzle diameter, mixing chamber length / mixing chamber diameter, nozzle location size of the parameter values. This method takes into account both the performance improvement and the widening of the availableload range in the ejector parameter optimization design phase, and provides an effective way to design hydrogen ejector with a wide range of available load range, which provides an effective way to solve the problem that the fuel cell ejector has a narrow working load range.

The invention belongs to the technical field of automatic control, and discloses an optimal robust fractional order PI for a time-delay system λ Optimization methods for D controllers. The method comprises the following steps: (a) constructing the closed-loop transfer function of the control system to be optimized; (b) obtaining the closed-loop transfer function with respect to the PI λ The characteristic equation of the unknown parameter in the D controller; (c) construct the constraint condition that the first-order inertia delay control system to be optimized needs to satisfy, utilize described characteristic equation to determine described PI λ The value range of the unknown parameter in the D controller is solved according to the constraints and the value range and the PI is obtained λ The values ​​of the unknown parameters in the D controller are used to determine the PI λ D controller, which realizes the optimization process. Through the present invention, the realization of PI λ The optimization of the D controller makes the control system have strong robustness and optimal dynamic performance.

The invention provides a vibration analysis method for a uniform section beam structure. The method comprises the steps that geometric size characteristics of the beam structure are extracted, a displacement field of the beam structure is separated to be in-section displacement and axial displacement; fitting is performed on the in-section displacement of the beam structure; extension is performedon the axial displacement of the beam structure; the in-section displacement and the axial displacement of the beam structure are combined to calculate integral displacement of the beam structure; strain vectors and stress vectors of an elastic plate structure are calculated; strain energy, a kinetic energy equation and boundary energy of the beam structure are calculated; a structural Lagrange energy function is established to obtain a core mass matrix and a stiffness matrix of the beam structure; an integral mass matrix, an integral stiffness matrix and an overall mass matrix are solved through iterative looping of the core matrix, and then a characteristic equation of the structure is obtained; and a characteristic equation matrix of the beam structure is solved, and inherent frequencyand a vibration mode are obtained through calculation. The method is suitable for the beam structure with multiple boundary conditions and multiple section shapes and is high in precision, fast in convergence, low in calculation cost and simple in calculation method.

The present disclosure belongs to the field of microgrid operation control, and discloses a method and system for analyzing the stability of a microgrid control period, establishing a small signal model of a microgrid distributed closed-loop control system in which each distributed power source corresponds to different control periods, and based on Euler discretization Obtain discrete characteristic equations, track the critical characteristic root locus of the system characteristic equations according to the least common multiple of multiple control periods, search for possible characteristic roots on the unit circle, and then calculate the control period to stabilize the microgrid, and control the control between different distributed power sources. The relationship between cycles is studied to provide a basis for the selection of distributed control cycles, to achieve average voltage recovery and active power equalization, and to improve the stability and dynamic performance of microgrids.

The invention discloses a vibration control method of a rigid-flexible coupling electromechanical servo system, comprising: separately collecting encoder data on a drive motor and a load motor, obtaining the torsion angles at both ends of a flexible shaft in real time, and calculating the flexible shaft The torsion angle of the micro-element at any position on the above is calculated according to the length, polar moment of inertia, elastic modulus and moment of inertia of the flexible shaft to obtain the frequency domain characteristic equation; using the frequency domain characteristic equation to calculate the described The coupling torque between the flexible shaft and the rigid drive flywheel; the balance equation of the rigid drive flywheel is established; the coupling torque is brought into the balance equation to obtain the fractional transfer function model of the system; according to the fractional transfer function model, establish a fractional order controller, and use the controller to control the vibration of the system. The method involved in this patent accurately describes the dynamic behavior of the viscoelastic material through the fractional order model, and effectively suppresses the residual vibration of the system.

The embodiment of the invention provides a method and system for analyzing the transient stable state and operation state of a power system. The method comprises the steps that: a generator power characteristic equation set of the power system is constructed; a generator power characteristic during normal operation of the power system, a generator power characteristic during a short-circuit faultof a line and a generator power characteristic after the cut-off of the fault line are constructed, and a corresponding power characteristic curve is drawn; and based on the power characteristic curve, a control strategy for maintaining the transient stable state of the power system is analyzed. According to the embodiment of the invention, the control strategy capable of keeping the transient stable state of the power system is found out by analyzing the power characteristics of the generator of the power system in different states, so that good normal operation of the power system is kept.