170results about How to "Increase stability margin" patented technology

All-internal compression inlets for supersonic aircraft, with variable geometry systems and shock stability bleed systems provide high performance, large operability margins, i.e. terminal shock stability that reduces the probability of inlet unstart, and contribute little or nothing to the overall sonic boom signature of the aircraft. These inlets have very high internal area contraction or compression and very low external surface angles. All shocks from the internal inlet surfaces are captured and reflected inside the inlet duct, and all of the external nacelle surfaces are substantially aligned with the external airflow. The inlet shock stability system consists of bleed regions that duct bleed airflows to variable area exits with passive or active exit area controls. This reduces the risk of inlet unstarts by removing airflow through a large open throat bleed region to compensate for reductions in diffuser (engine) corrected airflow demand. Because the stability bleed is not removed until the inlet terminal shock moves upstream over the bleed region, the necessary normal shock operability margin is provided without compromising inlet performance (total pressure recovery, and distortion).

The invention discloses a robust dicyclic photovoltaic grid-connected control method based on power feedforward, which mainly comprises three parts: proportion integration (PI) control of exocyclic voltage, dead-beat control of endocyclic robust predictive current and power feedforward control, wherein the exocyclic PI control of the voltage is used for stabilizing the capacitive voltage of a direct-current side; the dead-beat control of the endocyclic robust predictive current is used for carrying out linear prediction on the voltage of a power grid at a next control period and carrying out non-linear prediction on grid-connected current by advanced control so as to obtain the command value of the grid-connected current at the next period; and then, PWM (pulse-width modulation) and grid-connected control are realized by the dead-beat control. According to the robust dicyclic photovoltaic grid-connected control method based on the power feedforward, a photovoltaic grid-connected inverter has higher robustness, wider stability margin and quicker dynamic response, and the requirement of grid-connected running of an inverter is better met.

A reduced bitline precharge level has been found to increase the SRAM Beta ratio, thus improving the stability margin. The precharge level is also supplied to Sense amplifier, write driver, and source voltages for control signals. In the sense amplifier, the lower precharge voltage compensates for performance loss in the bit-cell by operating global data-line drivers with increased overdrive. In the write driver, the reduced voltage improves the Bitline discharge rate, improves the efficiency of the negative boost write assist, and decreases the reliability exposure of transistors in the write path from negative boost circuit.

The invention provides a reactive voltage optimal control method for a wind power plant cluster. The reactive voltage optimal control method comprises the steps that whether the reactive voltage optimal control for the wind power plant cluster needs to be carried out or not is judged; the reactive source equipment adjustment range of wind power plants and a pooling station in the wind power plant cluster region is obtained; and a reactive voltage optimal control mathematic model for the wind power plant cluster is built and solved. According to the reactive voltage optimal control method, a wind power plant cluster access point is used as a central voltage control node, the wind power plant grid-tied point bus voltage of the cluster region and a transformer tap of a booster station of the wind power plant are regulated, reactive compensation equipment of the pooling station is regulated to have reactive power, and a transformer tap of the pooling station is also regulated, the pilot node is enabled to meet the control instruction range of a dispatching mechanism, meanwhile the quiescent voltage stability margin of the cluster region is enabled to be maximum, and the active power transmission loss is enabled to be minimum; the quiescent voltage stability margin in the wind power plant cluster region can be effectively improved, the grid active loss in the cluster region also can be reduced, the operating safety and stability of a system are improved, and the capacity of digesting and saving wind power of the system is also improved.

The invention belongs to the technical field of grid-connection, control and protection of distributed type energy resources, and relates to a design method of improving a repetitive controller applied to grid-connected inverter current control. The method comprises the steps of determining a controlled object P (s) of a grid-connected inverter current control loop; determining the control feedback quantity of the grid-connected inverter current control loop; calculating an error signal under grid-connected inverter current control; determining and improving a repetitive controller structure; designing parameters for improving the repetitive controller, wherein the step comprises the procedures of designing a parallel-connection proportional controller proportionality coefficient Kp, a first-order low-pass filter Q (z) parameter, a compensator proportionality coefficient k, a second-order low-pass filter L (z) parameter and an m value of an advancing link zm. According to the design method of improving the repetitive controller applied to the grid-connected inverter current control, fast and precise tracking of a grid-connected inverter output current to a reference current can be achieved.

The invention relates to a method for controlling harmonic currents in a synchronous rotating reference frame by several times. Compensated harmonic currents at a certain time are converted to the synchronous rotating reference frame with the same times of rotating speeds and directions, harmonic instruction current information of an SFR is fully utilized, AC disturbance quantity brought by other nonsynchronous current components in the SFR is removed through a simple algorithm, so that the DC quantity corresponding to the compensated currents at the time in the SFR is extracted, and PI static-error-free decoupling control is achieved. The stability margin and the dynamic response speed of a control system can be effectively improved, and the steady state errors of the system are removed.

The invention discloses an active damping control method of an LCL grid-connected inverter under a static coordinate. The active damping control method comprises seven steps of 1, detecting a grid voltage and carrying out coordinate conversion; 2, detecting a current of a converter side and carrying out coordinate conversion; 3, controlling a DC voltage to obtain a DC reference value of an active current; 4, calculating a two-phase current reference value of the converter side; 5, controlling an AC current; 6, obtaining a compensation value of an output voltage of the inverter through an active damping network; and 7, generating a voltage space vector. With the adoption of the active damping control method, damping control on a resonant peak of an LCL filter can be effectively achieved on the condition that no extra sensor is additionally arranged, moreover, the complexity of an algorithm is simplified, the requirement of the algorithm on a high-performance digital controller is reduced, the efficiency of a system is effectively improved, and the cost of the system is effectively reduced.

The invention discloses a suspension rotor equivalent disturbance current compensation control device for a bearing-free permanent magnet synchronous motor. The control device is characterized in that: a generalized suspension system consists of an expended voltage controlled inverter, a current controller, a Clark transformer, a motor and a displacement sensor; observation and compensation algorithms are formed by connecting disturbance acceleration observers, equivalent disturbance current transforming links, composite radial displacement feedback, main controllers and composite controllers in sequence; two paths of observation and compensation algorithms are connected in series in front of the generalized suspension system and form a close-loop structure; and the control device is used for controlling a motor suspension system in a displacement ring of a bearing-free permanent magnet synchronous motor. The control device carries out the close-loop control on the displacement ring of the bearing-free permanent magnet motor suspension system of the consequent pole, and suppresses disturbance acting on the suspension system in a control mode of feedforward compensation. The control device observes disturbance acceleration generated by the suspension rotor of the motor because of disturbance effect through the disturbance observation algorithm in real time, and the algorithm does not dependent on a mathematical model of the suspension system and does not need to acquire specific forms of the disturbance in advance, so that the control device has wider adaptive range.

The invention provides an energy internet network and an energy distribution method for a plurality of direct-current power systems, and the method is simple, modularized, high in stability margin and independent. The distribution of energy is realized through current mode controlled bidirectional DC-DC converters, software and communication units in a traditional energy distribution method are replaced by using a sharing bus error amplifier (SBEA), and meanwhile, a traditional three-domain adjustment manner is replaced by a four-domain control manner. Communication equipment or a software algorithm is not needed in energy distribution, and only three conducting wires need to be connected; a plurality of systems using the same control manner participate the energy internet network through a unique analog control signal; more importantly, the energy distribution is automatically carried out, and the software algorithm is not needed; and the analog control is used, so that high stability margin, low output impedance and quick dynamic response of sharing bus are guaranteed.

The invention belongs to the technical field of power electronic device control, and relates to a power decoupling control method and system for a virtual synchronous generator based on voltage feedforward compensation. The method comprises the steps of firstly, acquiring output power Pvsg and Qvsg of the virtual synchronous generator; giving a reactive power reference value Qref, subtracting thereactive power Qvsg output by the virtual synchronous generator from the reactive power reference value Qref to obtain d-axis initial reference voltage V<d><ref'> through an inertia equation of a reactive power loop, setting the q-axis initial reference voltage V<q><ref'> to be 0 at the same time, then presetting voltage feedforward equivalent inductive reactance Xv, and generating feedforward voltage Xviod; and obtaining a voltage control loop reference instruction V<d><ref> according to the d-axis initial reference voltage V<d><ref'>, subtracting the feedforward voltage Xviod from the q-axisinitial reference voltage V<q><ref'> to obtain a voltage control loop reference instruction V<q><ref>, and finally generating an SVPWM control instruction through a voltage control loop and a currentcontrol loop according to the voltage control loop reference instruction. According to the invention, the coupling problem between active power output and reactive power output is significantly improved, and the capacity requirement of the inverter is reduced.

The invention discloses a multi-terminal offshore wind power flexible direct current and energy storage cooperative grid-connected system. The system comprises a plurality of offshore wind power clusters, a plurality of offshore converter stations connected in parallel, and land converter stations connected with the offshore converter stations. Each offshore converter station is directly connected with the output end of the corresponding offshore wind power cluster, and the direct current output ends of the offshore converter stations are connected in parallel; the land converter stations are connected to the AC main power grid; the energy storage subsystem is connected with the land converter station, comprises a plurality of energy storage units and is used for stabilizing offshore wind power output fluctuation; and the invention further discloses a corresponding control method. The branch type multi-terminal offshore wind power flexible direct-current power transmission subsystem integrates a plurality of dispersedly distributed offshore wind power clusters, shares a seabed transmission corridor and an onshore converter station, is connected with the energy storage subsystem at the onshore converter station, saves the seabed transmission corridor and landing point resources, reduces the network loss of a current collection system, smoothes the wind power output, and improving the flexibility, stability and reliability of offshore wind power generation.

The invention relates to the field of wind power generation, and specifically relates to a maximum available torque weak magnetic control method for a permanent-magnet direct-drive wind turbine. The method is characterized by comprising the following steps: obtaining a maximum wind energy tracking designing curve of the permanent-magnet direct-drive wind turbine: T<e><0>=MPPT(omega<t>), under a given rotating speed omega<t>, by taking a direct-axis current and a cross-axis current i<d> and i<q> as optimization variables, solving a constrained optimization problem in an off-line mode, taking i<dpt> and i<qpt> as the optimization variable solutions of the optimization problem, and obtaining weak magnetic currents of the maximum available torque weak magnetic control method, given i<d><0>=i<dpt>; changing a rotor rotating speed omega<t> by taking a proper step length delta omega<t>, i.e., enabling omega<t>= omega<t>+delta omega<t>; and connecting a series (omega<t>, i<d><0>) of points to form a curve so as to obtain a weak magnetic current given curve i<d><0>=MAT(omega<t>) under various rotating speeds. According to the particularity of wind turbine control, i.e., the overall control strategy of the turbine enables the torque instruction of a permanent-magnet synchronous generator and a current rotating speed to be in a one-to-one corresponding relationship, possibility is provided for simplifying the design of the weak magnetic controller of a wind turbine.

The invention provides a trans-impedance amplification circuit capable of realizing automatic gain control. The trans-impedance amplification circuit comprises a trans-impedance amplification front end circuit, a phase splitting circuit and an AGC feedback network, wherein the trans-impedance amplification front end circuit converts input current signals into voltage signals, and comprises a first switch tube, a second switch tube and a first MOS tube, a collector electrode of the first switch tube is connected with a base electrode of the second switch tube, a base electrode of the first switch tube is connected with an emitting electrode of the second switch tube through trans-impedance, a source electrode of the first MOS tube is connected with the base electrode of the first switch tube, a drain electrode of the first MOS tube (M0) is connected with the collector electrode of the first switch tube, the AGC feedback network comprises a peak value detection circuit and a comparison circuit, the peak value detection circuit detects differential voltage signals output by the phase splitting circuit and outputs direct current voltage, the comparison circuit detects the direct current voltage output by the peak value detection circuit and compares the direct current voltage with a reference level, and the output end of the comparison circuit is connected with a grid electrode of the first MOS tube.

The invention discloses a continuous tide calculation method based on a wind power fluctuation rule. The continuous tide calculation method comprises the following steps of: analyzing an active power fluctuation characteristic of a wind power field by adopting an analytical method in the poisson process, and constructing a probability model; determining a time interval of wind power outlet fluctuation and the output variation situation of the power of the wind power field according to the probability model and a statistical result of the wind power variation, thus obtaining the fluctuation rule of the wind power output; performing continuous tide calculation within the same time interval according to the fluctuation rule, thus obtaining a state variable value; and analyzing the state variable value, analyzing the influence of access of large-scale wind photoelectricity on the tide, thus obtaining the influence of wind power on the tide. According to the continuous tide calculation method based on the wind power fluctuation rule, advantages of wind power fluctuation compatibility and high calculation speed are realized; and due to application of actual power grid data, the correctness and the practicability are proved.

The invention discloses a pilot large-flow load control valve using a displacement and force feedback principle. The valve comprises a main valve body, a main valve sleeve, a main valve element, a feedback spring, a load pressure compensation damper, a pilot valve element, a pilot valve sleeve, a control spring, a control piston, a pilot valve body and an end cap. An oil return cavity, a load cavity, a control-sensitive cavity, a high-pressure cavity, an inner containing cavity of the pilot valve element, an oil drainage cavity and a channel communicating the load cavity and the high-pressure cavity are formed in the load control valve. The load control valve can control the load discharging speed of a hydraulic system with an exceeding load, and can effectively prevent the load speed fluctuation problem of a traditional load control valve. A vibration damping tail of the head portion of the main valve element offsets hydraulic force influences borne by the main valve element. The speed control function in load discharging and the one-way valve function in load rising are integrated on the main valve element so that the whole structure of the load control valve can be compact. The pilot valve element and the pilot valve sleeve are designed in a matched mode, so that the load control valve has a quick closing function.

The invention discloses a gas compressor blade top plasma stability expanding system. The system comprises a gas compressor blade, a high voltage electrode, a pressure sensor and a plasma exciter, wherein the high voltage electrode is arranged inside a machine case above the gas compressor blade, the high voltage electrode is opposite to the gas compressor blade, the upper side and the lower side of the high voltage electrode are coated with insulation materials, the pressure sensor is connected to a computer through a collection board card, the plasma exciter is connected to the high voltage electrode and the gas compressor blade at the same time through an amplitude modulation and frequency modulation circuit, and the amplitude modulation and frequency modulation circuit is further connected to the computer. By the utilization of the gas compressor blade top plasma stability expanding system, due to the fact that the whole system can be automatically controlled by the computer, the pressure sensor is utilized for detecting pressure signals on the inner wall face of a gas compressor, and leakage flow is blocked by plasma which can automatically detect stall foreboding when the gas compressor is in the stall condition approximately and is generated by discharging of a blade top and the machine case, so that flow losses are reduced, stability margin is expanded, and the aim of stall postponing is achieved.

The invention discloses a high efficiency and wide-range speed control method for a stator permanent magnet type memory motor. The method comprises the steps that the area where the motor rotating speed is located is judged through an area judging module, and different current distribution modes are adopted in different areas according to a division control strategy. In the low-speed area, a minimum value of which input power is in an AlNiCo permanent magnet flux linkage changing interval is looked up through a step-size adaptive search algorithm to achieve efficiency optimizing control of the motor, not only is the problem that a large error is generated when calculation is conducted by adopting a motor loss formula method avoided, but also inverter losses, stray losses and the like which are difficult to calculate through mathematical modeling are included in efficiency optimizing control, a difference from actual losses of a control system is decreased, and the efficiency optimizing control precision is improved. In the high-speed area, by means of the flux weakening method that a flux weakening flux linage needed in flux weakening control is obtained through a voltage difference method and a formula method, the stator permanent magnet type memory motor can achieve the high stability margin and dynamic property in a wide speed range.

The invention relates to an aircraft overload loop design method for providing damping by adopting angular acceleration and belongs to the technical field of aircraft control. According to the method,an angular accelerometer is adopted to measure the yaw angular acceleration of an aircraft to provide damping for an overload outer loop, then an accelerometer is adopted to measure the linear acceleration of the aircraft to obtain lateral overload; the lateral overload is compared with an expected overload instruction, and therefore, an overload error signal is obtained; integration is performedon the overload error signal twice, so that an overload error comprehensive integration signal can be formed, so that a conversion static error problem between the overload instruction and an attitude instruction can be eliminated; the nonlinear transformation signal of an aircraft attitude angular acceleration signal, the proportional signal of a yaw rate and the secondary nonlinear transformation signal of an aircraft angular speed signal are introduced to form the damping signal of the overload loop, and the damping signal is output to an attitude stabilization loop, so that the control objective of overload tracking can be realized. With the method adopted, the problems of static error and insufficient damping of traditional overload control can be solved.

The invention relates to an imported non-symmetrical casing unsteady generator under severe aberrance, comprising crescent chute disposal rings unsymmetrically distributed and a plurality of pitch-adjusting rings used for changing the advance quantity of the crescent chute. The disposal ring comprises an excitation area where disposal troughs are arranged and a solid wall area where no disposal troughs are arranged. The imported non-symmetrical casing unsteady generator under severe aberrance takes into account the unsymmetry and unsteadiness of inlet duct aberrance flow field under the great attack angle flying working condition of the aircraft, implements unsymmetrical unsteady excitation to the blade tip flow field of a compressor rotor, couples the unsymmetry with the unsymmetry, and reduces the separation volution strength and the dimension of the compressor; on the base that the stable working range of the compressor is widened and the pressure increment of the compressor is lifted, the pneumatic efficiency of the compressor is not reduced but improved by about 1%, thus fully improving the comprehensive pneumatic performance of the compressor.

The invention discloses a multisource system partitioning method considering voltage stabilization. The method includes: selecting time sections form researched time; increasing load of each node according to a system total load value of a first time section; subjecting various power sources to output increase and distribution; obtaining a system quiescent voltage stabilization critical point; performing modal analysis to obtain a node, weakest in voltage stabilization, of the time section; traversing all time sections, and taking the weak node highest in frequency of occurrence as a full-time-scale weak node; collecting time sections with solution results corresponding to the full-time-scale weak node, respectively obtaining weak areas of the time sections according to reactive voltage sensitivity relationship, and getting intersection of the obtained weak areas to form weak areas under a full time frame. The multisource system partitioning method considering voltage stabilization has the advantages that various power supply output features and load fluctuation are considered comprehensively, and voltage stability of a power system with various power sources can be improved beneficially.