304results about How to "Small voltage fluctuation" patented technology

A probing device for electrically contacting with a plurality of electrodes 3, 6 aligned on an object 1 to be tested so as to transfer electrical signal therewith, comprising: a wiring sheet being formed by aligning a plurality of contact electrodes 21, 110b, corresponding to each of said electrodes, each being planted with projecting probes 20, 110a covered with hard metal films on basis of a conductor thin film 41 formed on one surface of an insulator sheet 22 of a polyimide film by etching thereof, while extension wiring 23, 110c for electrically connecting to said each of said contact electrodes being formed on basis of a conductor thin film formed on either said one surface or the other surface opposing thereto of said insulator sheet of the polyimide film; and means for giving contacting pressure for obtaining electrical conduction between said extension wiring and said object to be tested by contacting tips of said projecting contact probe formed onto said each contact electrode through giving pressuring force between said wiring sheet and said object to be tested.

The invention discloses a triangular connection type comprehensive compensation system integrated with a cascaded active filter and a reactive compensator. The system comprises triangular connection type N-grade cascaded converters and a three-phase filter inductor connected with each N-grade cascaded converter; triangular connection type thyristor reactors and star-shaped connection type thyristors are used for switching the reactive compensator composed of fixed capacitors; and the triangular connection type N-grade cascaded converters and the reactive compensator are connected in parallel between a connection node and a ground node of an input power grid voltage and a load. According to the system provided by the invention, reactive power and harmonic current in a medium-voltage power grid are subjected to dynamic compensation and the efficiency of the power grid is improved; when the system is used for compensating, the system has no negative influences on the power grid, and has advantages of stable system, simple structure, strong stability and flexibility in compensation.

The invention provides a double-close-loop nonlinear compound control method for a three-phase four-wire parallel APF (active power filter). A voltage outer loop adopts a sliding-mode PI composite nonlinear control algorithm, and a current inner loop adopts a repeated PI nonlinear control algorithm. The method comprises the steps as follows: firstly, a low-order system model of a dq coordinate system is established by synchronous rotation coordinate transformation, a PI feedforward decoupling controller is designed according to a dq DC model, a PI repetitive controller is designed based on internal model control, and a control output function of the PI repetitive controller of the current inner loop is established; in order to obtain a current reference value of the current inner loop accurately and quickly, a novel sliding-mode PI nonlinear control algorithm for DC side voltage is proposed, a sliding-mode surface switching function is designed according to an exponential reaching law form, and a control function of a sliding-mode PI controller of the voltage outer loop is established. With adoption of the outer loop sliding-mode PI compound control algorithm, the steady-state performance and the response speed of the DC side voltage can be improved, and voltage fluctuation is effectively reduced; with adoption of the repetitive PI nonlinear control algorithm, zero static error tracking of a current signal can be realized, and the tracking control accuracy of a harmonic compensation current instruction is improved.

The invention relates to a method for tracing a maximum power point of a photovoltaic miniature grid-connected inverter. When the output power of a photovoltaic cell is high, the traditional continuous operating mode and a maximum power point tracing method are adopted; and when the output power of the photovoltaic cell is low, intermittent operating mode is adopted, namely operation is continuously performed for a plurality of periods with set power, then operation is stopped for a while to store energy to a capacitor, and simultaneously maximum power point tracing is performed with voltage change rate in the energy storage period, so as to ensure that the photovoltaic cell is operated at maximum power point voltage. The method can effectively solve the problems that the efficiency of a traditional inverter is low when the illumination intensity is low, grid-connected current harmonic wave is large, and the like.

A method and system for coordinate control of voltage and reactive power of a camera and an UHVDC convert station. The method comprises steps of keeping the AC filter bank switching strategy of DC control and protection system unchanged, Obtain the filter of DC control and protection, the switch instruction of reactor group, the operation mode and related control parameters and the operation stateof the adjuster, adjust the control target of the adjuster according to the switch instruction of DC control and protection, and intervene the switch instruction of AC capacitor and reactor output byDC control and protection. As that invention is base on the reactive power control of the UHVDC transmission and the exist control mode of the camera, The utility model can reduce the bus voltage fluctuation when the AC filter bank is switched on and off, reduce the switching times of the capacitor and the reactor bank, prolong the service life of the AC capacitor and the reactor, and at the sametime, do not need to change the DC control protection and the internal control logic of the adjuster, so that the utility model is convenient to implement.

The invention relates to a voltage control method for distribution network considering source-load coordination. The method calculating voltages of each node in distribution network, and directly outputting and ending the voltage regulation if the voltages of each node are within a prescribed range, Otherwise, determining whether the voltage exceeds the upper limit or not, and if the voltage valueexceeds the prescribed upper limit value at this time, carrying out the voltage control by using the source-charge coordinated voltage control model of a photovoltaic, an electric vehicle and an on-load tap changer; Otherwise, inducing the capacitor in the control measures to exceed the lower limit value, and the voltage control model including photovoltaic, electric vehicle, on-load tap changerand capacitor will be used to control the voltage. The optimal solution of the voltage regulation model of source-charge coordination is used to regulate the voltage. Combined with the interaction among load side, power side and grid side, considering the uncertainty condition and demand side response characteristics, it solves the problem of distribution network voltage exceeding limit under different meteorological factors considering photovoltaic grid-connected.

The invention discloses a parallel APF DC side voltage control method based on a sliding mode PI compound control algorithm. The method comprises the following steps: firstly establishing a low-order system model of a dq coordinate system by using synchronous rotating coordinate transformation; determining the sliding mode switching function of the DC side voltage according to the selection principle of sliding mode surfaces; and finally designing the control parameter output function of a PI controller according to the switching function of the sliding mode surfaces. By adopting the control method disclosed by the invention, the steady state performance and response speed of the DC side voltage can be improved, and the voltage fluctuation can also be effectively reduced; and a parallel APF control system based on the sliding mode PI compound control algorithm has good robust performance and dynamic performance. According to the parallel APF DC side voltage control method based on the sliding mode PI compound control algorithm disclosed by the invention, the parameter of the PI controller is determined through the sliding mode controller, the steady state accuracy and response speed during load sudden change and reference voltage jump can be increased, the power loss at the DC side can be reduced, and thus the compensation ability of the parallel APF (active power filter) can be ensured.

The invention discloses a three-level bidirectional direct-current converter and a pulse width control method thereof and relates to the technical field of power conversion of power electronics. A first filter capacitor and a second filter capacitor on the high-voltage direct-current side of the three-level bidirectional direct-current converter disclosed by the invention can realize self-balance control within a carrier cycle under a pulse width control method, so that the voltage fluctuations of the capacitors can be reduced effectively; the voltage stress of a power device can be equalized to beone half of the voltage on the high-voltage direct-current side, and pulse width voltage amplitudes outputted by two half-bridges are one half of the voltage on the high-voltage direct-current side, so that a filter inductance value and the capacities of the capacitors can be reduced, and dv/dt (change in voltage over change in time) is also reduced; and compared with the traditional three-level bidirectional direct-current converter, the three-level bidirectional direct-current converter disclosed by the invention does not need a transformer while realizing energy conversion with large conversion ratio between the high-voltage direct-current side and the low-voltage direct-current side and can further prevent a power switch from working in an extreme duty cycle state.

The invention discloses a thermal battery positive electrode material and a preparation method thereof. Tungsten (molybdenum) metal ions are used as a positive electrode material of an electron acceptor; the main components of the positive electrode material comprise tungsten (molybdenum) sulfide, an additive, an electronic conductive agent, an ion conductive agent and a binder; through steps of ahigh-temperature roasting process, a vacuum-atmosphere replacement roasting process, an additive passivation treatment process, a mechanical activation roasting process, a crushing, sieving and packaging process and the like, the contents of volatile and decomposed impurities are reduced, the stability of the positive electrode material is improved, and the battery safety is improved. The positive electrode material disclosed by the invention is good in thermal stability, high in material utilization rate, small in self-discharge, large in output capacity and long in working time, and is an ideal positive electrode material of a high-capacity long-time thermal battery.

The invention relates to a method for accessing low-frequency wind generator into electric network, wherein it uses wind generators, low-frequency boost transformer, high-voltage low-frequency transmission line, alternative-alterative converter, and work-frequency boost.

The invention discloses a modular multilevel converter quasi-two-level PWM control method based on an SIC device. The method comprises the steps of determining a reference value of output voltage anda duty ratio of an output PWM modulator by current control, determining a PWM switching state time signal according to the duty ratio D of the PWM modulator, determining a circulation reference valueaccording to a PWM switching state and an energy reference value, determining a compensation voltage reference value according to a circulation actual value and the circulation reference value, and finally superposing the compensation voltage reference value on the reference voltage to obtain an output voltage modulation signal, and carrying out delay PWM modulation to obtain each bridge arm sub-module PWM control signal to realize the control of each sub-module of a modular multi-level converter. According to the method, a phenomenon of excessive output voltage is effectively prevented, the voltage fluctuation of a modular multilevel converter sub-module capacitor is reduced, requirements of energy storage of the sub-module capacitor are reduced, the volume of the modular multilevel converter is further reduced, and the cost of the modular multilevel converter is reduced.

The invention provides an automatic voltage control device and a control method for a distributed photovoltaic power station. The control device comprises a communication management module, a command processing module, an AVC module, a data management module and an information displaying module. The communication management module is in charge of receiving and transmitting real-time information with a connected device. The command processing module is in charge of converting formats of remote regulation and remote control orders received and transmitted by the communication management module. The AVC module is used for carrying out reactive power control on photovoltaic inverters of the whole station and an SVC/SVG system through the preference control strategy of the inverters according to the real-time information received at present and can control tap positions of a transformer substation, and therefore the busbar voltage of the current power station meets the requirement of power grid dispatching.

The invention provides a modulation strategy of a DC (Direct Current)-DC convertor and a submodule voltage-sharing method thereof. The modulation strategy comprises the following steps: 1) constructing a switching function model of a submodule; 2) determining a ladder undulant bridge arm switching function model; and 3) according to the ladder undulant bridge arm switching function model, modulating the alternating-current side voltage current waveform of the DC-DC convertor. The voltage-sharing method comprises the following steps: constructing an energy model, and changing energy interaction on the submodule by primary side alternating current on the basis of the energy model so as to balance submodule voltage. Compared with the prior art, the modulation strategy of the DC convertor and the submodule voltage-sharing method thereof can improve the intermediate alternating current voltage frequency of the DC-DC convertor on the premise that switching frequency is not improved, reduce capacitance voltage fluctuation, reduce the volume of submodule capacitance in the convertor, are favorable for reducing the volume of passive devices including a bridge arm inductor, a transformer and the like, lower cost and cause the DC-DC convertor to own high power transmission capability and power density.

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 provides a high-voltage reactive power automatic compensation device, belongs to the technical field of reactive power compensation of a power grid, and solves the problems of low power quality and poor stability of the power grid when the conventional device is used in a 35KV transformer substation. The high-voltage reactive power automatic compensation device comprises a vacuum circuit breaker, a switching capacitor group, a controller, a current sensor and a voltage sensor, wherein the switching capacitor group is used for changing a power factor; the wire inlet side of the vacuum circuit breaker is connected with a three-phase generatrix; the wire outlet side of the vacuum circuit breaker is connected in series with a reactor and an intelligent switching switch in sequence; the intelligent switching switch is connected with the switching capacitor group; the current sensor is used for detecting the current of each phase of the three-phase generatrix and the voltage sensor is used for detecting the voltage of each phase of the three-phase generatrix; the current sensor and the voltage sensor are both connected with the input end of the controller; and the output end of the controller is connected with the intelligent switching switch. The device does not generate a harmonic wave in use, and is low in loss and high in grid power quality and stability.

The invention discloses a phase modifier constant voltage control method and system coordinated with extra-high voltage direct current converter station reactive voltage control and a medium. The method comprises the following steps executed after a filter bank or capacitor bank switching instruction is sent out by direct-current control protection: calculating the deviation between estimated target voltage and an initial voltage target after a small filter group/capacitor group is switched in; and correcting the voltage control target of a phase modifier according to the deviation between theestimated target voltage and the initial voltage target after delaying for a specified time, and adjusting the steady-state reactive output of the phase modifier to zero or a specified numerical value of which the difference value with zero is less than a preset threshold value. According to the invention, the internal control logic of an existing direct-current control protector is not requiredto be changed, the control mode of the phase modifier can be simplified from a double-loop mode to a single-loop control mode, the phase modifier and an alternating-current filter group, a capacitor and a reactor controlled by a direct-current control protection system can be simply and effectively coordinated and controlled, and the dynamic regulation capability of the phase modifier is fully exerted.

The invention discloses a load current feedforward control method of a dual-active-bridge converter based on three-phase shift modulation, and belongs to the field of bidirectional DC-DC converters for energy storage in the field of power electronics. The load current feedforward three-phase-shift control strategy based on a dual-active-bridge DAB converter is used for controlling the dual-active-bridge DC-DC converter; a primary side and a secondary side of a main circuit of the dual-active-bridge DC-DC converter are full-bridge circuits; the two full bridges are connected together through aseries inductor and a transformer; the primary side is connected with a storage battery, and the secondary side can be connected with any load; and bidirectional power flow control is achieved by controlling the duty ratio of full bridges on the primary side and the secondary side of the converter and phase shift angles corresponding to two full-bridge voltage waveforms, and the dynamic response of the converter is improved through feedforward control over output current. Rapid dynamic response of the dual-active-bridge (DAB) converter under a three-phase-shift control strategy can be realized, and the dynamic process is stable without oscillation.

The invention relates to an energy consumption brakingbraking device and method for the servo driver. The energy consumption braking device comprises a current sampling module, a rotation speed outputting module, an inertia identifying module and a braking controlling unit; the current sampling module is used for detecting the current signal Ir flowing through the braking resistor R and outputting the current signal to the braking controlling unit; the rotation speed outputting module is used for outputting the running rotation speed (omega)s and the given rotation speed (omega)ref of the servo motor; the inertia identifying module is used for obtaining the current rotating inertia Js of the servo motor; the braking controlling unit pre-calculates according to the control algorithm to obtain the feedback energy (delta)W, and calculates the braking energy consumption (delta)Wf in real time according to the current signal Ir flowing through the braking resistor in the braking process, and makes the feedback energy (delta) W be equal to the braking energy (delta)Wf through the feedback controlling link, so as to realize the energy consumption braking process.