57results about How to "Resolve volatility" patented technology

The invention belongs to the field of power converter control and relates to a model prediction control method of a voltage source type rectifier when a network voltage is unbalanced. The model prediction control method of the voltage source type rectifier when the network voltage is unbalanced comprises the steps of converting three-phase network voltage and a three-phase current into network voltage and a current which are under a two-phase static coordinate system through an abc / alpha beta coordinate, obtaining network positive sequence voltage and negative sequence voltage by carrying positive and negative sequence component separation of the network voltage under the two-phase static coordinate system, calculating reference values of active power, calculating current reference values of the rectifier under the two-phase static coordinate system, and carrying out model prediction current control and selecting an optimal on-off state. The model prediction control method of the voltage source type rectifier when the network voltage is unbalanced is capable of quickly and precisely tracing the current under the two-phase static coordinate and effectively eliminating fluctuation of direct current side voltage at the same time, power quality of the system is improved, a reliable network-connected operation of the rectifier when transient state network voltage is unbalance is achieved, and dynamics and stability of the whole system are improved.

The invention discloses a high-temperature molten salt electriochemistry testing system applicable to a temperature range of 750 DEG C - 900 DEG C; the high-temperature molten salt electriochemistry testing system comprises a high-temperature electric resistance furnace, high-temperature electriochemistry electrodes and a high-temperature molten salt crucible. A high-temperature molten salt reference electrode (2) is mainly composed of a first electrode stem (24) and a sleeve; the first electrode stem (24) is packaged in a first aluminum oxide sleeve (25) sealed by cement (27); a high-temperature molten salt working electrode (3) is mainly composed of a second electrode stem and a sleeve; the main body of the second electrode stem is packaged in a second aluminum oxide sleeve (32) including sealing cement, thus ensuring heat insulation and uniform distribution of heat under the condition of high temperature; a crucible cover (64) which is provided with a central hole (65) and made of ceramic is placed at the top of the crucible (6); the crucible cover (64) can effectively prevent electrolyte from volatilizing due to melting in high temperature, and thereby the furnace body of the electric resistance furnace is prevented from being eroded by volatilization of the molten electrolyte.

The embodiment of the invention provides a control method and system of a permanent magnet synchronous motor, and belongs to the control field of the permanent magnet synchronous motor. The control method of the permanent magnet synchronous motor comprises the following steps: determining an assumed angle of a rotor of the permanent magnet synchronous motor about an assumed rotational coordinate system at the first time of the starting stage, wherein the constancyof the specific value of the voltage vector amplitude, which is corresponding to the single current loop input,relative to the rotation speed of the rotor is maintained at the starting stage; acquiring the actual angle of the rotor about the actual rotational coordinate system at the first time; computing the first angle difference value between the assumed angle and the actual angle, and judging whether the first angle difference value is in the angle difference threshold range; and judging whether the first duration time of the angle difference value in the angle difference threshold range is greater than the time threshold; if the first duration time is greater than the time threshold, switching the permanent synchronous motor to a closed loop control state. Therefore, the closed loop switching stability of the motor is improved.

The invention discloses a molten salt heat storage solar thermal power generation system. The system comprises a heat collecting subsystem, a heat storage subsystem, a steam generation subsystem and a power generation subsystem connected in sequence; the heat collecting subsystem is connected with the heat storage subsystem; the heat storage subsystem is connected with the steam generation subsystem; and the steam generation subsystem is connected with the power generation subsystem. As the connecting relation of the steam generation subsystem to the heat collecting subsystem and the heat storage subsystem is improved, the power load output stability of the power generation subsystem is improved; and the power load output by the system is not changed along with the change of solar radiation, so that the load fluctuation is largely reduced, and the whole control operability of a power station is promoted.

The invention discloses a three-phase electric and electronic transformer based on a multi-level multi-module cascade structure. The three-phase electric and electronic transformer has three levels, i.e. an input level, an isolation level and an output level. An output end of an input-level power converter is connected with an input end of a high-frequency DC/AC (direct current/alternating current) link power converter; an output end of the high-frequency DC/AC link power converter is connected with the primary side of a high-frequency transformer; the secondary side of the high-frequency transformer is connected with the input end of the high-frequency DC/AC link power converter; the output end of the high-frequency DC/AC link power converter is connected with an input end of an output-level power converter; an output end of the output-level power converter is connected with an input end of an LC wave filter; and the LC wave filter is connected with a three-phase power supply network. Basic functions, such as transformation, isolation and energy transfer of the traditional electric transformer can be realized, and for the input voltage with different levels, corresponding voltage can be born only by calculating the corresponding number of input-level serial modules and serial connection according to corresponding module number.

The invention discloses a video mixing encoding system and a method. The video mixing coding system comprises an encoder, a memory and a player. The video mixing coding system is characterized in that the encoder, the memory and the player are mutually connected through a data network; the encoder comprises a mixing encoding system and an encoding scheme selection module; the mixing encoding module uses at least two encoding schemes to perform encoding on video data to be encoded to obtain data of at least two encoded videos; the encoding scheme selection module chooses data of one or more than one videos from the data of the encoded video data to transmit to the memory or the player; the encoding scheme comprises an encoding protocol, screen resolution and image quality; and the various encoding schemes are combined through regulating the three various parameters The video mixing coding system fully utilizes the video data flow transmission capability, enables the video stored by the memory to achieve the best effect and does not cause the loss of the video data due to the fluctuation of the data network.

The invention discloses a three-phase power electronic transformer capable of balancing asymmetric load. The transformer is divided into an input level, an isolation level and an output level, output ends of input-level power converters are connected with input ends of high-frequency DC (direct current)/AC (alternating current) link power converters, output ends of the high-frequency DC/AC link power converters are connected with primary sides of high-frequency transformers, secondary sides of the high-frequency transformers are connected with the input ends of the high-frequency DC/AC link power converters, the output ends of the high-frequency DC/AC link power converters are connected with input ends of output-level power converters, and output ends of the output-level power converters are connected with input ends of LC filters which are connected with a three-phase power supply network. The three-phase power electronic transformer capable of balancing asymmetric load can realize basic functions of transformation, isolation, energy transfer and the like of conventional power transformers, and as for input voltages of different levels, the serial module number of corresponding input levels only needs to be calculated, and corresponding voltage can be borne by serial connection according to corresponding module number.

The invention discloses a design method of a width of an effective surface of an overflow brick for controlling the average thickness of an edge plate. According to the design method, started from a width WG of a target glass substrate, a width WY of a guide board of the glass substrate and a width WE of an effective surface of an overflow brick are calculated through introduction of a correctioncoefficient, and then an manufacturing average thickness TE of an edge plate of the glass substrate is calculated; an overflow coefficient for calculating the WE is continuously adjusted, so that thefinal TE meets design requirements; namely, the thickness TE of the edge plate of the glass substrate meets the design requirements through the design of the width WY of the guide plate and the widthWE of the effective surface. Process parameters are used for calculating other parameters of the overflow brick at the same time, and the process parameters comprise a guide plate speed V, an averageedge plate flow QE and an average edge plate mass ME, so that technological requirements of manufacturing stable guide plates in a glass substrate production line can be met. Through the design method, a problem of guide plate fluctuation of the field forming is effectively solved, and then the forming thickness distribution of the glass substrate manufacturing is optimized, so that production margins are increased from design, and consistency of thickness of the edge plate of the glass substrate is guaranteed.

The invention discloses a zero-flashing low-voltage distribution system and an operation method thereof. The zero-flashing low-voltage distribution system comprises a first power supply, a second power supply, an emergency bus, a second dual-power automatic changeover switch or a solid-state changeover switch, wherein the first power supply and the second power supply are connected with two ordinary buses in a switching station respectively; one end of the emergency bus is connected with a mobile emergency power supply and the first power supply separately through a first dual-power automaticchangeover switch; the other end of the emergency bus is connected with a static energy storage uninterruptible power supply at a user side; the second dual-power automatic changeover switch or the solid-state changeover switch is in load connection with a user. The zero-flashing low-voltage distribution system and the operation method thereof have the advantages that the power supply switching operation of the dual-power automatic changeover switches at a load side under the fault is avoided, thereby solving the problem of load flashing caused by voltage sag during power supply switching, andsolving the problem of voltage fluctuation; if the static energy storage uninterruptible power supply breaks down or is not replenished by the power supplies before a battery runs out, the power supplies are switched to a right circuit for power supply, and sensitive load flashing caused by the voltage sag can occur during power supply switching.

The invention relates to a frequency hopping channel selection method and device, a communication method and device and a communication system. The method comprises the following steps: acquiring transmitting power information of a plurality of first channels in a working frequency band range of a transmitting end and signal intensity attenuation information of a plurality of second channels in a working frequency band range of a receiving end; acquiring signal strength information of the plurality of channel groups according to the transmitting power information and the signal strength attenuation information; and obtaining first probability distribution according to the signal strength information, and selecting a plurality of first alternative channel groups corresponding to the signal strength information distributed in a preset probability range in the first probability distribution as a target channel group, so as to improve the fluctuation problem introduced by different gains and insertion losses of different frequency bands on hardware, and improve the accuracy of interaction. Meanwhile, the target frequency hopping group is selected in advance before communication interaction, so that the time spent on frequency hopping channel selection in the communication interaction process can be shortened, and the communication efficiency is improved.

The invention relates to the technical field of UAVs (unmanned aerial vehicles), in particular to a barometric height detection device and a UAV (unmanned aerial vehicle). The barometric height detection device is arranged on the UAV and comprises a barometric sensor, a sensor protecting cover and a guide pipe, wherein the barometric sensor is sealed in the sensor protecting cover; the barometricsensor and the sensor protecting cover are mounted on the UAV; one end of the guide pipe is communicated with the sensor protecting cover, the other end of the guide pipe penetrates out of the sensorprotecting cover and then extends upwards to be away from blades, so that an external environment where the barometric sensor is located can be effectively isolated from turbulent flow produced by blade rotating, disturbance of an unstable barometric pressure environment on the barometric sensor is avoided, and accurate detection for barometric height is guaranteed; besides, the barometric heightdetection device is simple in structure, reasonable in design, low in production cost and good in detection effect.

The invention provides a method for removing impurity silver in reduced gold powder. The method comprises the following steps of primary digestion, washing, secondary digestion and drying. According to the method, the impurity silver in the reduced gold powder is removed by adding independently prepared boiling washing liquid A and boiling washing liquid B into the reduced gold powder with relatively high silver content step by step, so that the purification of the coarse gold powder is realized, the problems of gold product fluctuation or gold powder reworking and the like caused by trace silver impurities are solved, the direct recovery rate of gold is improved, the reworking cost is reduced, and the production and operation indexes in the gold smelting process are comprehensively improved; the method can be applied to precious metal purification processes and precious metal separation processes.

The invention discloses a delay tripping low-voltage frame switch. The frame switch comprises an under-voltage tripping loop and a time delay unit electrically connected with the under-voltage tripping loop; the time delay unit comprises a voltage detection circuit, a timer circuit, a clock control circuit and a voltage stabilizing circuit; the input end of the voltage detection circuit is electrically connected with the output end of the under-voltage tripping loop; the output end of the voltage detection circuit is electrically connected with the input end of the timer circuit; and the inputend of the clock control circuit and the input end of the voltage stabilizing circuit are electrically connected with the output end of the timer circuit. The delay unit is additionally arranged on an original under-voltage tripping loop, so that the under-voltage tripping loop has a voltage-loss delay disconnection function, power grid fluctuation can be avoided, the delay time is adjustable, and the safety performance is good.