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5966 results about "Grid voltage" patented technology

Grid voltage. [′grid ‚vōl·tij] (electronics) The voltage between a grid and the cathode of an electron tube.

Air conditioner and filth blockage detection control method and device therefor

The invention belongs to the field of control of household appliances and particularly relates to an air conditioner and a filth blockage detection control method and device therefor. The device can be installed on an indoor unit of the air conditioner or an outdoor unit of the air conditioner, so that the corresponding air conditioner, the indoor unit thereof and the outdoor unit thereof are also provided. The method has the advantages that filth blockage of a filter screen of the indoor unit and / or a heat exchanger of the outdoor unit can be accurately detected; if filth blockage is detected, the indoor unit displays the filth blockage state through a filth blockage reminder unit to remind a user of handling; the outdoor unit directly controls a motor positively and reversely rotate to allow automatic dust removal after the air conditioner is off, and manual intervention is not required; the technical problem that the prior art fails to accurately detect the filth blockage state of the filter screen of the air conditioner and / or the heat exchanger of the air conditioner is solved; the demand of users for accurate detection and timely dust removal is met; the device and the method are also applicable to variable frequency machines and fixed frequency machines and is insusceptible to voltage of users' power grids; cooling and heating effects of the air conditioner are guaranteed; health of users and comfort are improved.
Owner:GD MIDEA AIR-CONDITIONING EQUIP CO LTD

Control method applied to active-clamp flyback miniature photovoltaic grid-connected inverter device

The invention relates to a control method which can be applied to an active-clamp flyback miniature photovoltaic grid-connected inverter device. The active-clamp flyback miniature photovoltaic grid-connected inverter device comprises a flyback converter and a power frequency polarity conversion circuit. In the device, a current reference is used for controlling a flyback primary-side current peak value so that the device can output a half-wave sinusoidal current, and the output voltage is clamped by a grid voltage. When the instantaneous power is lower, a constant frequency current discontinuous mode in combined with a variable frequency current critical continuous mode is adopted in the flyback control method. When the flyback converter works in a variable frequency current critical discontinuous mode, an auxiliary switching tube can be conducted for a period of time when the secondary-side current of the flyback converter reaches zero, the conduction time can be accurately controlled by a digital chip, thus realizing the leakage inductance energy feedback and the soft switch of a master switching tube under the condition of wide-range output voltages and different instantaneous powers and greatly improving the efficiency under the condition of full loads.
Owner:ALTENERGY POWER SYST

Photovoltaic three-phase grid control method for fast and steadily implementing maximal power tracing

The present invention relates to a photovoltaic three phase synchronization control method realizing maximum power tracking swiftly and stably, which belongs to the technical field photovoltaic power generating control. The method includes the steps as follows: judging the DeltaP/DeltaV value according to the power difference DeltaP between the current time k and the previous time and the voltage difference DeltaV; working out the Iref(k) when the photovoltaic array produces the maximum power; using the Iref(k) to adjust the uq* under the coordinates in vectorial synchronous rotation with the electric network voltage; acquiring six ways of space vectorial SVPWM impulse series according to the rotation angle degree Theta of the three phase electric network voltage, with the aim to control the inverter in order to ensure that the output current of the photovoltaic inverter has the same phase position as that of the mains voltage while ensuring the photovoltaic array is realizing the maximum power output tracking. The power factor is 1. The present invention also can adjust the Idref(k) according to local load requirements, therefore achieving adjustment to the power factor, with low synchronization current harmonic wave distortion factor.
Owner:TSINGHUA UNIV

Coordination control and optimization method for battery energy accumulation and photovoltaic power generation based on co-direct current bus

The invention discloses a coordination control and optimization method for battery energy accumulation and photovoltaic power generation based on a co-direct current bus in synchronization and independent operation modes, which supports the access of various types of storage batteries and photovoltaic battery boards through the free combination of the co-direct current bus of a DC (Direct Current)/DC converter, the automatic intelligent charge-discharge management of a storage battery branch and the maximum power tracing management of a photovoltaic battery board branch, wherein the branches are completely independently controlled to realize optimization management; the energy collected by a direct current bus is interacted with the energy of a power grid or an independent load through a post DC/AC (Alternating Current) converter; the DC/AC converter adopts a method for carrying out directional vector control on the voltage of the power grid and modulating the space vector pulse widthof the voltage in the course of the synchronization operation in an active and reactive complete decoupling control mode; and V/f control is adopted in the course of the independent operation to provide a constant voltage and frequency reference to an alternating current bus. The result of an experiment proves that the invention can realize the coordination complementary control and the autonomous optimization management of photovoltaic power storage and has the advantages of good generality, practicality and application prospects.
Owner:BEIJING SIFANG JIBAO AUTOMATION +1

Advanced real-time grid monitoring system and method

This invention deals with an advanced Real-time Grid Monitoring System (RTGMS) suitable for both single-phase and three-phase electric power systems. This invention provides an essential signal processing block to be used as a part of complex systems either focused on supervising and diagnosing power systems or devoted to control power processors interacting with the grid. This invention is based on a new algorithm very suitable for real-time characterization of the grid variables under distorted and unbalanced grid conditions. The main characteristic of this invention is the usage of a frequency-locked loop, based on detecting the grid frequency, for synchronizing to the grid variables. It results in a very robust system response in relation to existing technique based on the phase-angle detection since grid frequency is much more stable variable than the grid voltage/current phase-angle, mainly during grid faults. Moreover, the algorithm supporting this invention is very efficient and can be implemented in regular industrial microprocessors. These features make the RTGMS object of this invention ideal to be applied in the control of distributed generation systems (DGS), flexible AC transmission systems (FACTS), power quality conditioners (PQC) and uninterruptible power supplies (UPS). In all these systems, the fast and precise real time detection of the voltage and/or current sequence components under grid fault conditions is a crucial matter.
Owner:GAMESA INNOVATION & TECH SA

Grid connection presynchronization control method of microgrid inverter based on droop control

The invention relates to a grid connection presynchronization control method of a microgrid inverter based on droop control. When the microgrid operates in island, as a voltage source type inverter which functions as the support in the microgrid works in accordance with droop characteristic, a microgrid voltage has a deviation from a high power grid voltage; and the problem of synchronization between the microgrid voltage and the high power grid voltage during the grid connection is the key to realize smooth switchover. The grid connection presynchronization control method provided by the invention comprises the following steps: obtaining frequency and phase position information of the high power grid voltage through a three phase software phase-locked loop (SPLL); carrying out dq (Direct Quadrate) conversion to an output voltage of the inverter based on a power grid voltage phase obtained from the locked phase; subsequently carrying out PI (Physical Impairment) regulation on a q-axis component; overlapping a synchronization angle frequency output by a PI regulator with an angle frequency generated by the droop control to be used as a reference angle frequency of the output voltage of the inverter; and finally realizing the tracking and synchronization of the output voltage of the microgrid inverter to the high power grid voltage through the closed-loop control. The impact current during the grid connection is avoided effectively.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS +1

Active and reactive coordination control method for permanent-magnet direct-driven wind turbines in low-voltage ride-through process

Enclosed is an active and reactive coordination control method for permanent-magnet direct-driven wind turbines in the low-voltage ride-through process. Two different control strategies are employed for a grid side converter according to amplitude change of power grid voltage: when the power grid voltage is in a normal state, the grid side converter is in an active-priority maximum power tracing control mode so that the wind turbines capture wind energy to the maximum extent; when the power grid voltage is beyond the normal range, the grid side converter is in an active priority control mode so that the dynamic reactive current which is injected into an electricity system meets the requirements of grid combining. An engine side converter is in a direct-current voltage control mode based on rotor energy storage, power unbalance of the direct-current side of the engine side converter is relieved and the direct-current voltage is stabilized by utilizing the self rotating speed of the permanent-magnet direct-driven wind turbines and the change of the kinetic energy. The active and reactive coordination control for the wind turbines before or after the sudden change of the power grid voltage is realized according to the amplitude change of the power grid voltage, the fluctuation of the direct-current bus voltage is restrained by releasing or storing the rotor kinetic energy, so that the low-voltage ride-through capability of the permanent-magnet direct-driven wind turbines is improved, reactive power support is rapidly and accurately provided for the power grid, and certain support is given to restoration of the power grid voltage.
Owner:NORTH CHINA ELECTRIC POWER UNIV (BAODING)

Parallel structure and control method for photovoltaic power generation grid-connected inverter

The invention discloses a parallel structure and a control method for a photovoltaic power generation grid-connected inverter and belongs to the technical field of renewable energy sources. A topological circuit structure of the photovoltaic power generation grid-connected inverter is divided into a parallel structure of single-phase voltage type pulse-width modulation (PWM) inverters and a parallel structure of three-phase voltage type PWM inverters; and in the control method, an outer ring regulator of a control circuit of the parallel voltage type PWM inverters is independent based on a power grid voltage-oriented vector control technology in a control mode of voltage outer ring and current inner ring so as to form a common unified outer ring regulator; control strategies of various inverters are simplified into single closed loop current control so as to achieve the consistency of energy flow directions of the parallel voltage type PWM inverters and avoid ring current; and the parallel current sharing of the voltage type PWM inverters is realized. Therefore, multiple modules of the voltage type PWM inverters are connected in parallel to realize high-power modularized large-scale application.
Owner:NORTH CHINA ELECTRIC POWER UNIV (BAODING)

Model prediction control method of voltage source type rectifier when network voltage is unbalanced

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.
Owner:TIANJIN UNIV

Low voltage traversing control method of wind generator set

A response control method for the lower voltage traversing of a wind generating set is characterized in that changing situation of the voltage us of a power network is detected at any time; the power the voltage us of the power network is compared with a reference value of the voltage us of the power network, and a wattless current iqref<*> as well as an effort current idref <*> are obtained by an obtained difference value Delta u through a PI adjustor; the wattless current iqref<*> is taken as the reference value for the inner loop control of the circuit to cooperate with the control strategies of the outer loop of the voltage and the inner loop of the circuit to control a network side inverter and restrain the depreciation of the voltage of the power network as well as the effect loss of the compensating chain of the effect circuit idref<*>. Under the situation that the voltage of the power network declines instantly, the invention can flexibly feed corresponding reactive powers according to requirements, adjust the effect power correspondingly as well, lead the wind generating set to reach a transmission reliability standard similar to a fire generating set, and has the capacity of self adjustment.
Owner:INST OF ELECTRICAL ENG CHINESE ACAD OF SCI
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