163results about How to "Improve dynamic response speed" patented technology

The invention discloses a multi-terminal VSC-HVDC grid-connected transmission system controlling method applied to a large wind power plant. Wind power plant side convertor station outer ring power conducts inner ring current PI control, a grid field side convertor station outer ring direct voltage conducts inner ring current feedback linearization decoupling control, and therefore response characteristics and dynamic performance of a controller are improved. When operation of the wind power plant fluctuates greatly and a system loses capacity for adjusting the direct voltage, multi-terminal direct voltage control of direct voltage deviation is led into other convertor stations of the wind power plant for replacing a grid side convertor station to execute a voltage regulating task, therefore, power balance is maintained, normal operation of the system is ensured, and the effect that the system operates stably at a new operating point is also ensured.

The invention provides a grid-connected photovoltaic power generating system based on a novel direct current converter and a working method of the grid-connected photovoltaic power generating system. The grid-connected photovoltaic power generating system is characterized in that the grid-connected photovoltaic generating power system consists of a direct current converter, a grid-connected inverter, an isolation transformer and a control circuit; the working method comprises the steps as follows: 1. collecting signal; 2. MPPT module data processing; 3 applying an MPPT arithmetic; 4 inverter module data processing; 5. applying a grid-connected arithmetic; and 6. applying SPWM arithmetic. The grid-connected photovoltaic power generating system and the working method thereof have the advantages of small technical realization difficulty, obviously reducing the cost, flexible installation, convenient maintenance, high voltage and current detection precision, advanced control arithmetic, quick running speed of control chip, the system being capable of obtaining excellent tracking precision and stability, combining the hardware device with the software programming of a digital signal processor, simple design, low cost and easy realization of the hardware device, brief and understandable software programming arithmetic.

The invention relates to the field of brush direct current motor speed regulating control, in particular to a compensation feedback speed regulating device of a brush direct current motor and a method therefor. The method realizes the speed regulating control to the brush direct current motor via acquiring and analyzing speed gain links of the voltage signal of the motor and current compensation control links of a motor working current signal; the speed gain links provide voltage feedback; and the current compensation feedback control links provide wasted current feedback used for compensating consumption and caused by the motor armature inner resistance; and a feedback controller of the device provided by the invention comprises the two links, and the device can also be used for achieving the method. The invention has the benefits that close-cycle control to the rotation speed of the motor is achieved via the speed gain link; an extra speed sensor is not required; the rotation speed deviation of the load change, which is caused by the motor armature inner resistance, is corrected by the current compensation control links; and the control is simple, the cost is low, and the universal property is high.

The invention provides a micro fluid flow adjusting device based on air pressure drive, belongs to the field of micro fluids, and aims to solve the problems of low flow adjusting precision, low dynamic response speed and absence of capacity of measuring actual flow when an injection pump is adopted to adjust the flow in a micro fluid system. The micro fluid flow adjusting device adopts an air pressure drive mode, an air supply source supplies compressed air, outlet pressure is adjusted and set by a pressure reducing valve to obtain stable air supply pressure, the pressure is measured by a pressure sensor, a liquid in a liquid container passes a valve and a flow meter to enter a liquid micro-channel under the pushing of the air pressure, the actual liquid flow is measured by the flow meter and fed back to a microprocessor, the microprocessor outputs a control signal to change the working state of a micro valve, the liquid flow of the liquid micro-channel is adjusted, and closed-loop control of the flow is realized; further, a PID (proportion integration differentiation) control algorithm can be adopted, the adjusting precision and the dynamic response speed of the flow can be increased, and the liquid flow in the micro-channel can be adjusted accurately and rapidly.

A six-freedom-degree heavy load static balance parallel motion simulation table mechanism with a balancing mechanism mainly comprises a moving platform, a foundation platform, a bearing platform, six driving branches exactly the same in structure and three balancing branches exactly the same in structure. The moving platform, the foundation platform and the driving branches for connecting the moving platform and the foundation platform form a parallel driving mechanism. The bearing platform, the foundation platform and the balancing branches for connecting the bearing platform and the foundation platform form a parallel balancing mechanism. The six driving branches are of a UPS structure which is composed of an electric cylinder, a first ball hinge and a first universal hinge. The three balancing branches are of a UPU structure which is composed of a balanced hydraulic cylinder or a balanced air cylinder, a second universal hinge and a third universal hinge, and the bearing platform is connected with the moving platform through the second ball hinge. The six-freedom-degree heavy load static balance parallel motion simulation table mechanism is strong in bearing capability and fast in dynamic response, the balancing mechanism has no inertia force (moment) when the moving platform rotates, the bearing platform has a vertically upward force on the moving platform, and no component in other directions exist.

The invention discloses a sliding-mode variable structure control method of a variable exponential coefficient reaching law of a permanent magnet synchronous motor. The method comprises the following steps: aiming at the requirements of a control system of a high-performance permanent magnet synchronous motor, a variable exponential function term formula is introduced on the basis of a conventional exponential reaching law; the formula takes a first-order norm of systematic state variables as an exponent of exponential functions, adaptively adjusts the reaching speed of a variable exponent term and a variable speed term according to the distance between the system and a sliding-mode surface, and is helpful to increase the dynamic response speed of the system; the systematic state variables are associated by taking the first-order norm of the systematic state variables as the exponent of the functions; and an s function is introduced to replace a symbolic function for further suppressing system chattering. Therefore, the sliding-mode variable structure control method of the permanent magnet synchronous motor using the variable exponential coefficient reaching law is provided. Compared with an integral-type sliding-mode variable structure control method, the method disclosed by the invention can be used for effectively increasing the dynamic characteristics and steady state characteristics of the system as well as increasing the robustness of the system.

A method for circulating current restraining of a parallel system of dual grid-connected inverters based on zero voltage vector feedforward control belongs to the technical field of circulating current restraining of the parallel system of dual grid-connected inverters. The method solves the problem of existing system circulating current restraining methods that the dynamic response is slow when given current of two inverters changes. The dual grid-connected inverters share an alternating current bus and a direct current bus, and the method for circulating current restraining is based on the method for controlling proportional integral (PI) of parallel systems of inverters, introduces feedforward control of the difference between a non-zero vector and a duty ratio in space vector pulse width modulation (SVPWM) of two inverters, has high dynamic response speed and good control effect and is applicable to restraining the circulating current to a small range when the given current of one inverter is different from that of the other inverter. The method is applicable to parallel structures of three-phase grid-connected inverters without neutral lines.

The invention discloses an effluent and drain temperature measurement and calculation method of a heater with a drain cooler on a steam turbine. The method comprises the following steps: a machine set design condition or a performance test condition is selected as a reference condition; the case side pressure, the case side steam extraction enthalpy, the drain temperature, the effluent temperature, the inflow temperature and the machine set power of the heater under the reference condition are selected to calculate the heat transfer characteristic coefficient of the pure condensation section and the drain cooling section of the heater under the reference condition; the case side pressure, the heater inflow temperature and the machine set power under the actual condition are read or calculated in the database of a monitoring information system SIS or a decentralized control system DCS of a heat-engine plant; the heat transfer characteristic coefficient of the pure condensation section of the heater under the actual condition is calculated by the corresponding heat transfer characteristic coefficient of the pure condensation section of the heater under the reference condition; the actual effluent temperature is obtained by iterative computation; the heat transfer characteristic coefficient of the drain cooling section of the heater under the actual condition is calculated according to the heat transfer characteristic coefficient of the drain cooling section of the heater under the reference condition, and the drain temperature is obtained by iterative computation.

A double parallel type heavy-duty static balance motion simulation platform mainly comprises a motion platform, a base platform, a load-bearing platform, six driving branches and three load-bearing branches, wherein the six driving branches are completely identical in structure, and the three load-bearing branches are completely identical in structure. The motion platform, the base platform and the driving branches connected with the motion platform and the base platform constitute a parallel driving mechanism. The load-bearing platform, the base platform and the bearing branches connected with the load-bearing platform and the base platform constitute a parallel load-bearing mechanism. Each of the six driving branches is in an uninterrupted power supply (UPS) structure and is composed of an electric cylinder, a first spherical hinge and a universal hinge. Each of the three load-bearing branches is in a strategic petroleum reserve (SPR) structure, and is composed of a balance hydraulic cylinder or a balance air cylinder, a second spherical hinge and a rotational joint. The load-bearing platform is connected with the motion platform through a third spherical hinge. The double parallel type heavy-duty static balance motion simulation platform is strong in bearing capacity, quick in dynamic response speed, simple to control, and suitable for indoor and field environments, and simultaneously reduces extra load caused by the load-bearing mechanism.

The invention discloses a frequency stabilization circuit for a non-contact energy transmission system, which includes an inverter, a primary side resonance circuit, a secondary side resonance circuit and a power adjustment circuit; it is characterized in that: the primary side resonance circuit is connected with a frequency detection circuit The input end of the frequency detector is connected between the primary side resonant capacitor and the excitation coil, and its output end outputs the primary side resonant frequency value f1 to the first input end of the controller, and the second input end of the controller is input to the system setting The resonant frequency value f0 is fixed, the output control terminal of the controller is connected with the parallel capacitor array, and the parallel capacitor array is connected in parallel with the primary side resonant capacitor, and the controller controls the capacitance value of the parallel capacitor array according to f1 and f0. Its remarkable effect is: the circuit structure is simple, the control algorithm is easy to implement, the system has good dynamic response speed, stability and anti-interference, and the frequency stability can be guaranteed during the load change process to realize the maximum energy transmission of the system.

The invention discloses a single-phase PWM rectifier dynamic performance optimization control method based on active disturbance rejection control. The method adopts double closed-loop control of a voltage outer loop and a current inner loop, the current inner loop adopts single-phase DQ current decoupling control and the voltage outer loop adopts active disturbance rejection control. In particular, according to the principle of power conservation, a mathematical model for active DC components isd of single-phase PWM rectifier output DC voltage udc and grid-side AC voltage is deduced; and according to the mathematical model, a voltage outer loop active disturbance rejection controller is designed. In comparison with the traditional single-phase DQ current decoupling control voltage outer loop adopting PI control, the voltage outer loop in the invention adopts active disturbance rejection control, and while grid-side unit power factor operation and DC-side voltage stable control are realized, the dynamic response speed of the system is better and the anti-interference ability is stronger.

A three-transfer-one-shift four-degree-of-freedom heavy-load static-balance parallel motion simulation stand mechanism mainly comprises a basic platform, a motion platform, a load-bearing platform, four driving branches in identical structures and three balancing branches in identical structures. The four driving branches are connected with the motion platform and the basic platform to form a parallel driving mechanism. The three balancing branches are connected with the load-bearing platform and the basic platform to form a parallel balancing mechanism. The four driving branches are in uninterrupted power supply (UPS) structures and are composed of electric cylinders, first spherical hinges and universal hinges. The balancing branches are in RPS structures and are composed of balancing hydraulic cylinders or balancing air cylinders, first revolving pairs and second spherical hinges. The motion platform is connected with the load-bearing platform through a second revolving pair. The mechanism is high in bearing capacity, fast in dynamic response speed, simple to control, capable of preventing the three balancing branches from generating moments of rotation around a shaft and reducing the inertia force (moment) of a parallel load-bearing mechanism simultaneously and applicable to motion simulation of large devices, and the mechanism can be used indoors or in a field environment.

The invention discloses a compound control method and system based on a plug-in type rapid repetitive controller. The compound control method comprises: a repetitive controller internal module is formed by a positive feedback path and a repetitive control gain module, an internal model low-pass filter, a compensator module, and a feedforward gain channel are designed in the repetitive controller to form a new plug-in type rapid repetitive controller; and the output of the plug-in type rapid repetitive controller controls a controlled object by the input of the feedback controller, so that error-free tracking of a reference signal or elimination of all harmonics is realized. According to the invention, on the premise that stability of the controlled object is guaranteed by the feedback controller, the introduced feedforward gain module and the traditional repetitive controller are connected in parallel to form a novel plug-in type rapid repetitive controller that is capable of carrying out error-free tracking or elimination of all harmonics; and a defect of a slow dynamic response of the traditional repetitive controller can be overcome and the dynamic response speed of the whole controller is improved.

The invention discloses a photovoltaic power generation maximum power tracking method capable of correcting open-circuit voltage online in order to solve the problem that when outside environment temperature greatly changes, a photovoltaic array cannot quickly track the maximum power point. The method is characterized by including the steps of building a model of a given temperature and an irradiance photovoltaic cell, building a model of different temperatures and the irradiance photovoltaic cell, improving the maximum power tracking control strategy of the open-circuit voltage, a grid-connected inverter control strategy and other contents, and building a photovoltaic power generation system including a photovoltaic cell model, a boost chopper circuit and a grid-connected inverter through PSCAD / EMTDC simulation software; the open-circuit voltage is updated according to outside environment changes, so that the photovoltaic system is stabilized at the maximum power point quickly; the incremental conductance method is introduced to improve the steady-state performance at the maximum power point so as to further improve energy conversion efficiency of the photovoltaic power generation system; an effective means is provided for improving the maximum power point tracking efficiency of the photovoltaic array and reducing energy loss of the photovoltaic array.

The invention discloses an optimization control method for a Boost PFC comprising an active energy storage unit, and belongs to the field of AC-DC power conversion. The invention aims at a problem of reference distortion, caused by the condition that an output voltage of a rectifier bridge is taken as a sine reference, in a conventional Boost PFC mean current control method. The method comprises the steps: converting an input sine voltage into a square signal through a square wave conditioning circuit, enabling a digital controller to capture the rising and falling edges of the square signal, and generating a pure sine signal as a sine reference through an anti-error capturing phase-locking algorithm, so as to improve the reference distortion; deducing an input feedforward and load feedforward algorithm on the basis that a sine reference control method is generated, so as to improve the capability of an output voltage in resisting input and load disturbance and increase the tangential velocity of a light load tangential algorithm. The method achieves the deduction of an input current of the active energy storage unit as the reference through the generated sine signal and the output current, and saves a band-pass filter circuit which samples the input current reference of the active energy storage unit. Moreover, the method improves the power density and efficiency of a converter.

A power equalization device for parallel inverter based on current sag characteristics and a control method are disclosed. The power equalization device comprises a DC voltage stabilized power supply,an inverter control unit and a central controller. Each inverter control unit includes a three-phase inverter and an improved current sag control module. The output current of the three-phase inverter is synthesized by the improved current sag control module, and then the SPWM wave is output through the voltage-current dual-loop controller and the SPWM pulse modulation module to control the inverter. Central control acquires instantaneous value of output current at common couple point for [alpha] [beta] transformation, calculates the instantaneous reactive current, according to the ratio of the reactive current value of each three-phase inverter in the parallel inverter to obtain the average value of the reactive current as the reference value of the inverter, The reference value is transmitted to each reactive current sample value and subtracted to make difference and multiplied by the integral constant feedback, and the reactive output bias is adjusted by the following action of theintegral regulator, so that the reactive current is proportionally divided according to the capacity, and the circulating current is eliminated.

The invention discloses an MPPT (Maximum Power Point Tracking) algorithm for a photovoltaic module based on parameter identification. The MPPT algorithm comprises the following steps of obtaining the current environment condition and a corresponding I-V output characteristic curve of the photovoltaic module in real time; utilizing an IAFSA (Improved Artificial Fish Swarm Algorithm) to carry out parameter identification on equivalent parameters in the photovoltaic module according to sampling points of the current I-V output characteristic curve; obtaining maximum output power under the current work condition by carrying out explicit solution on the output power of the photovoltaic module through a Newton iteration method; adopting an adaptive PI (Proportional Integral) control algorithm to realize MPPT of the photovoltaic module; and if a change value of the output power exceeds a preset value, restarting the Newton iteration solution process to realize a new round of MPP (Maximum Power Point) searching process. According to the MPPT algorithm, the problems of slow dynamic response and poor steady accuracy of the conventional common MPPT algorithm for the photovoltaic module are effectively solved.

The invention discloses a common-rail fuel supply system of fuel cells or multi-fuel engines, which comprises a fuel source and a fuel conveyer pipe; a valve, a pressure regulator, and a common-rail injection apparatus are serially connected on the fuel conveyer pipe; the common-rail injection apparatus comprises a front and a back fuel rails, and a plurality of injectors parallelly connected between the two fuel rails; input ends of the injectors are all connected with the front fuel rail, and injection ends of the injectors are all connected with the back fuel rail. The invention brings into full play of the advantages of a fuel cell system, effectively solves the problem of pressure balance of a fuel cell electric pile, and greatly improves the service life of the fuel cell electric pile; the invention precisely and rapidly controls the fuel supply amount, and increases the control precision and the dynamic response speed; the invention realizes a simple structure, low cost, a long service life, and long-lasting stable and reliable operation of a fuel cell system or a fuel cell engine system, is applicable to transportation means such as automobile and the like, and meets the special requirements of zero discharge, large power, and fast dynamic response.

The invention provides a system for driving a four-wheel full-drive electric vehicle dragged by winding type asynchronous motors; the system is characterized by comprising a driver operating mechanism, a vehicle steering mechanism, a differential control mechanism, an energy management system, a storage battery, four independent traction control systems, four power conversion units and four winding type asynchronous traction motors, wherein the driver operating mechanism is connected to the vehicle steering mechanism on the one hand, and is connected to the differential control system on the other hand; the vehicle steering mechanism is also connected to the differential control system; the differential control system is respectively connected with the four independent traction control systems; the four independent traction control systems are respectively connected with the four power conversion units in a way of one-to-one correspondence; and the four power conversion units are respectively connected with the four winding type asynchronous traction motors in a way of one-to-one correspondence; and the energy management system and the storage battery are respectively connected with the four power conversion units. The system is capable of more effectively improving the maneuvering capability and the stability of the vehicle.

The present invention relates to miniature fluid control element in precise machine and astronautics, and is especially miniature integral cold air propeller for satellite posture and position control. The pressure reducer, cut-off valve, shared seat, valve base, valve cap, sealing film and other parts constitute one integral structure, and the miniature planar nozzle is set near the air outlet of the cut-off valve. Elastic film and plate spring are used in the reducing and stabilizing of high pressure air to simplify the structure, machining and installation. Rolling ball valve core is used to raise the control pressure of the cut-off valve, and permanent magnetic suction is used to provide sealing pressing force of the cut-off valve and the restoring force of actuator. The main parts of the pressure reducer and the cut-off valver are in planar structure and integrally designed, and this makes it possible to transplant to planar miniature technique, and integrating the structural parts can omit assembly, reduce size and raise integration degree and control precision.

The invention discloses a direct suspension force control method for a permanent-magnet-type bearing-free motor, and the method belongs to a bearing-free motor control method. The method controls the crest value and the direction of the space vector of a suspension winding stator flux through properly selecting the switch state of an inverter while maintaining the invariableness of an air-gap-flux composed by motor winding, and the suspension is controlled by adopting a closed loop, thereby further decoupling the torque control winding and the suspension winding. The invention is a control method with high suspension control precision, fast dynamic response and small motor parameter influence.

The invention discloses a calibration device for an exhaust gas analyzer. The calibration device is used for reducing the material cost and labor cost of calibration working of the exhaust gas analyzer. The calibration device is characterized in that a host computer comprises a Fuzzy-PID compound control module, wherein the input end of the Fuzzy-PID compound control module is connected with the signal input end of the host computer and a gas concentration sensor and the output end of the Fuzzy-PID compound control module is connected with a control hole of a mass flow controller. A PID control algorithm is adopted by the Fuzzy-PID compound control module provided by the invention under a small deviation condition, a Fuzzy control algorithm is adopted under a large deviation condition, the stability performance and the dynamic performance are excellent and a gas distribution system has relatively high stability precision and relatively high dynamic response speed.

The invention discloses an effluent and drain temperature measurement and calculation method of a steam turbine surface-type heater. The method comprises the following steps: a machine set rated power design condition or a performance test condition is selected as a reference condition; the thermal parameter of the j-grade heater under the reference condition is selected; the heat transfer characteristic coefficient of the pure condensation section of the heater under the reference condition is obtained by calculation according to a heat transfer equation of the pure condensation section; according to the heat transfer characteristic coefficient of the pure condensation section of the heater under the reference condition, the numerical experimentation, the model parameter identification algorithm based on a sample and the machine set power Pe under actual conditions, the heat transfer characteristic coefficient of the heater under the actual conditions is obtained; and finally, according to the heat transfer characteristic coefficient under the actual conditions, the effluent temperature under the actual conditions is calculated, wherein, the drain temperature under the actual conditions is equal to the saturation temperature corresponding to the side pressure of a heater case under the actual conditions.

The invention provides a high anti-interference fast response control system and method for a resonance type DC-DC converter and belongs to the technical field of advanced control of efficient power conversion systems. The system comprises a tracking differentiator, a linear expansion state observer and a sliding mode controller; the tracking differentiator outputs a tracking signal, a first-orderdifferential signal and a second-order differential signal according to a received voltage reference signal; the linear expansion state observer obtains a first estimation state, a second estimationstate and estimation disturbance according to a received signal, and then obtains a first error signal and a second error signal; the sliding mode controller outputs a control signal according to a preset sliding mode control law, the received first error signal, the received second error signal, the received second-order differential signal and the estimated total disturbance, and generates a PWMdriving signal through a driving generator to drive the switching tube of the converter to act. The method has the high anti-interference characteristic of active disturbance rejection control and the fast dynamic response characteristic of sliding mode control, and can effectively relieve a buffeting problem easily caused by traditional sliding mode control.

The invention discloses a plug-in type rapid repetitive controller and a control method. The controller is composed of a feedforward gain module, a repetitive control gain module, a positive feedback gain module, two additive loops, an internal model constant module or an internal model low-pass filter, an internal model time-delay module, and a compensator module. The method is characterized in that a repetitive controller internal module is formed by a positive feedback path and the repetitive control gain module, the an internal model low-pass filter, the compensator module, and a feedforward gain channel are designed in the repetitive controller to form a new plug-in type rapid repetitive controller, thereby realizing error-free tracking of a reference signal or eliminating harmonic. According to the invention, the introduced feedforward gain module and the traditional repetitive controller are connected in parallel to form a novel plug-in type rapid repetitive controller that is capable of carrying out error-free tracking or elimination of all harmonics; and a defect of a slow dynamic response of the traditional repetitive controller can be overcome and the dynamic response speed of the whole controller is improved.

The invention provides a parallel interleaving BUCK converter and a control method. The converter comprises a direct-current voltage source, a parallel interleaving BUCK circuit, a sampling circuit, a digital signal processor and a PWM (Pulse Width Modulation) driver, wherein the parallel interleaving BUCK circuit is connected with the direct-current voltage source and comprises two sets of parallel rectifier switch transistors and two sets of fly-wheel switch transistors connected with the two sets of the rectifier switch transistors; each set of the rectifier switch transistors and each set of the fly-wheel switch transistors comprise two parallel MOSFETs (Metal Oxide Semiconductor Field Effect Transistors); the sampling circuit performs sampling on an output voltage and an output current of the parallel interleaving BUCK circuit and outputs a sampling result; the digital signal processor is connected with the sampling circuit, processes the sampling result according to a fuzzy genetic algorithm to obtain a duty ratio signal, and outputs a PWM wave corresponding to the duty ratio signal; and the PWM driver is connected with the parallel interleaving BUCK circuit and the digital signal processor, controls the two sets of the rectifier switch transistors to be switched on at an interleaving angle of 180 degrees according to the PWM wave, and controls the two sets of the fly-wheel switch transistors to be switched on at the interleaving angle of 180 degrees.

The invention discloses an axial electrical excitation composite rotor circumferential misplacement reluctance motor control system and method, and belongs to the technical field of electrical appliance automatic control. The axial electrical excitation composite rotor circumferential misplacement reluctance motor control system comprises a DSP (Digital Signal Processor), a position sensor, a speed sensor, a current sensor, a level reversion chip, a three-phase asymmetrical half-bridge power converter, a driving circuit and the like. A controlled motor comprises a motor revolving shaft, a magnetic conductive material, a central electric excitation coil, a stator salient pole, a rotor salient pole and the like. The method comprises the following steps: generating a new PWM (Pulse-Width Modulation) duty ratio according to data transmitted by the position sensor, the speed sensor and the current sensor through the DSP; and adjusting current of a three-phase winding or adjusting current of the electric excitation coil. The electric excitation coil is arranged between two groups of stators, and a rotor circumferential misplacement structure is adopted for running, so that crest connection of torque between two sets of stators and rotors is realized effectively. Double-closed-loop PI (Proportional-Integral) control is adopted, so that the dynamic response speed and interference resistance of the control system are improved greatly, and efficient continuous speed adjustment control of a motor can be realized easily.

The invention discloses a unified power quality conditioner. The unified power quality conditioner comprises a voltage and current collection module, an analog-to-digital conversion module, a DSP operation control module, a drive level conversion module and a main circuit which is composed of a series-type APF, a parallel-type APF and a direct-current-side capacitor. Aiming at the problem that a traditional detecting algorithm based on an instantaneous reactive power theory cannot accurately detect the distortion amount when network voltage is distorted, the invention further provides a methodfor using the unified power quality conditioner to detect the harmonic distortion amount and an improved comprehensive detection method of the synchronous rotation coordinate transformation deformation amount. Meanwhile, a novel digital lowpass filter is adopted by the method, a traditional lowpass filter is replaced through series connection of an improved moving averaging filter and a Butterworth filter, the calculating amount and the storage space are greatly reduced, the dynamic response speed is increased, and the detection of the network voltage and the load current distortion amount can be quickly and accurately conducted.

Disclosed is a jet-flow tube electro-hydraulic servo valve driven by piezoelectric ceramic. The servo valve comprises a main valve, a piezoelectric ceramic pre-stage and a feedback rod. The piezoelectric ceramic pre-stage is fixed with the main valve body through screws, and it is ensured that a jet-flow tube nozzle is aligned with a receiver; one end of the feedback rod is connected with a main valve core through a clamping screw, and the other end of the feedback rod is connected with a jet-flow tube. According to the jet-flow tube electro-hydraulic servo valve driven by the piezoelectric ceramic, the displacement of piezoelectric ceramic stacks is amplified through the adoption of the lever principle, so that it is possible to use piezoelectric ceramic to drive the jet-flow tube; by taking the advantages of the piezoelectric ceramic materials that the dynamic responding speed and the control precision are high, the dynamical responding speed and control precision of the jet-flow servo valve are improved; the piezoelectric ceramic materials have no electromagnetic interference and are simple and reliable without electromagnetic shielding.