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44 results about "Three phase system" patented technology

Three Phase System. Definition: The system which has three phases, i.e., the current will pass through the three wires, and there will be one neutral wire for passing the fault current to the earth is known as the three phase system.

Power quality disturbance positioning identification method based on phase perception and multi-modal fusion

The invention discloses an electric energy quality disturbance positioning identification method based on phase perception and multi-mode fusion, and relates to the technical field of electric power system monitoring and fault diagnosis. The electric energy quality disturbance positioning identification method based on phase perception and multi-modal fusion comprises the following steps: acquiring an original voltage signal of a three-phase electric power system; extracting a sample embedding vector of each phase based on the original voltage signal, comparing the sample embedding vector with a normal sample vector, and determining a disturbance phase with power quality disturbance in combination with an adaptive threshold value; performing time sequence feature vector extraction and bispectrum image feature extraction on the disturbance phase, and performing alignment and collaborative fusion to obtain fusion features; the electric energy quality disturbance type is identified based on fusion features, phase-level positioning of the three-phase PQD is achieved, through an innovative phase perception embedding and prototype comparison mechanism, accurate and rapid positioning of abnormal phases in a three-phase system is achieved for the first time under the condition of not depending on disturbance phase labels, and the core pain point of a traditional method is solved.
Owner:ANHUI UNIV

Intelligent grounding inrush current suppression method and device for power distribution network

The embodiment of the invention discloses a power distribution network intelligent grounding inrush current suppression method and device, and the method comprises the steps: collecting the state data of a power distribution network, and generating a line state data set, the state data comprising real-time load characteristics and impedance parameters; analyzing the line state data set based on an edge calculation model, and predicting an inrush current peak value and a waveform characteristic of the inrush current peak value at the grounding moment in combination with a nonlinear load fluctuation characteristic caused by the access of a distributed power supply; a particle swarm optimization model is constructed according to the predicted inrush current peak value, waveform characteristics and load characteristics, a search space is constrained through a local heuristic rule, capacitance and resistance parameters of an RC damping loop are dynamically adjusted, and an optimal damping scheme is generated; on the basis of inter-phase cooperative control logic of a three-phase system, dynamically determining grounding trigger time sequences of all phases in combination with the predicted inrush current waveform characteristics; and a grounding instruction is sent to the three-station integrated mechanism, and the three-station integrated mechanism executes an inrush current suppression operation. According to the invention, efficient inrush current suppression is realized.
Owner:HUANGHUA POWER SUPPLY COMPANY OF STATE GRID QINGHAI ELECTRIC POWER +1

Zero line disconnection detection method and device

The invention relates to the technical field of power systems, and discloses a null line disconnection detection method and device, and the method comprises the steps: calculating a three-phase voltage unbalance degree according to a negative sequence voltage and a zero sequence voltage; judging whether the three-phase voltage unbalance degree exceeds a first preset threshold value or not; if the three-phase voltage unbalance degree exceeds the first preset threshold value, whether the difference value between the third harmonic content and the second harmonic content in the three-phase voltage exceeds a second preset threshold value or not continues to be judged; and if the difference value between the third harmonic content and the second harmonic content exceeds a second preset threshold value, determining that the zero line is disconnected. As the null line is disconnected, the third harmonic is obviously increased, and the second harmonic is slightly changed, the neutral line fault and other disturbances can be effectively distinguished through the difference between the third harmonic and the second harmonic. The zero-sequence component and the negative-sequence component are coupled, the three-phase voltage unbalance degree is calculated, the unbalance state of a three-phase system is represented more comprehensively and accurately, and the harmonic characteristic difference of each split-phase voltage is combined and can be effectively applied to neutral line fault detection.
Owner:ZHEJIANG CHINT INSTR & METER

Three-phase voltage state estimation method and system based on virtual coordinates

The invention relates to the technical field of three-phase systems, and provides a three-phase voltage state estimation method and system based on virtual coordinates, and the method comprises the steps: calculating the voltage peak value of each phase for three-phase voltages, and determining that a phase is open if the peak voltage of a certain phase is lower than a threshold value in the three peak voltages; for three-phase voltage, virtual beta-axis voltage is generated through an all-pass filter, actual beta-axis voltage is obtained through Clark transformation, the product of the virtual beta-axis voltage and the actual beta-axis voltage serves as an evaluation function, and a positive sequence and a negative sequence are distinguished according to the positive and negative of the evaluation function. The system state can be accurately and effectively judged under the conditions of three-phase imbalance and voltage distortion, the anti-noise capability and the anti-harmonic interference capability are high, and safe and stable operation of equipment under the abnormal condition is ensured.
Owner:RODLESS PUMPS INC +2

Four-phase high-power motor driving device and fault-tolerant control method and system

The invention provides a four-phase high-power motor driving device and a fault-tolerant control method and system, and relates to the field of multi-level power electronic conversion. The driving system is composed of a four-phase modular multilevel converter and a four-phase input-three-phase output AC-AC frequency converter, the MMC outputs four-phase intermediate-frequency AC voltage with the phase difference of pi / 2, and the four-phase AC-AC frequency converter converts the intermediate-frequency voltage into low-frequency voltage for driving a motor. According to the method, one phase is added on the basis of a three-phase system, so that the whole system has additional fault-tolerant capability, and when the MMC detects that the fault number of a certain bridge arm sub-module is greater than the number of redundant sub-modules, the MMC can be converted into the three-phase system by cutting off the corresponding fault phase, so that the normal operation of the motor under the fault is ensured.
Owner:SOUTHEAST UNIV

Operationally reliable brushless DC motor

ActiveCN115004516BMagnetic circuitBlood pumpsRat heartThree phase system
The present invention relates to a brushless DC motor, in particular for an actuator unit of an implant, preferably for a heart assist system, comprising a stator and a rotor, the stator having a hollow cylindrical ironless winding, and a rotor rotatable relative to the stator, the rotor comprising a shaft with p permanent magnet pole pairs, the winding having n three-phase systems separated from one another. For a number of permanent magnet pole pairs p=1, the number of three-phase systems separated from one another is 2, and for a number of permanent magnet pole pairs p>1, the number of three-phase systems separated from one another corresponds to either an integer divisor of p (wherein the integer divisor is not equal to 1), or to the number p, or to twice the number p of permanent magnet pole pairs, wherein the n three-phase systems separated from one another in the hollow cylindrical ironless winding are arranged spatially offset from one another by an angle of 360° / n.
Owner:MCKESSON INT AG

Three-phase UPS system and power supply equipment

The invention discloses a three-phase UPS system and power supply equipment, and relates to the technical field of three-phase UPS systems. Wherein one phase of the three-phase branch comprises a bidirectional PFC circuit, the other two phases of the three-phase branch comprise a double-BOOST PFC circuit, or one phase of the three-phase branch comprises the double-BOOST PFC circuit, and the other two phases of the three-phase branch comprise the bidirectional PFC circuit. Therefore, the three-phase branch can convert a three-phase power supply of a power grid into a direct-current power supply through the bidirectional PFC circuit and the double-BOOST PFC circuit and output the direct-current power supply to the UPS bus, and / or output a power supply of a battery to the UPS bus through the double-BOOST PFC circuit, and feed back redundant power supply on the UPS bus to the power grid through the bidirectional PFC circuit. Therefore, a battery discharge circuit does not need to be additionally configured, the circuit cost is saved, the electric energy on the UPS bus can be fed back to the power grid, and the feed energy can be effectively utilized.
Owner:SHENZHEN AICHEN DIGITAL ENERGY CO LTD

Transformer three-phase imbalance treatment method and system based on big data

The invention relates to the technical field of power distribution networks, in particular to a transformer three-phase imbalance treatment method and system based on big data. Firstly, three-phase power values of power distribution network users are collected through an intelligent electric meter, a power mean value is determined through the three-phase power values, and N-phase power of a power distribution network is calculated based on the three-phase power values of the power distribution network users and the power mean value; and then calculating the three-phase unbalance degree of the power distribution network based on the three-phase voltage value of the power distribution network user, judging whether a three-phase system needs load switching based on the three-phase unbalance degree, and then formulating a control adjustment strategy of load switching according to the size and relation of the three-phase active power. Based on the adjustment strategy, selecting a phase-change switch to carry out phase-change switching of the load, so that partial load or load combination in the heavy-load phase is switched to a light-load item; when the method is used for monitoring, evaluating and controlling the distribution transformer district based on a certain frequency, the dynamic unbalance degree of a three-phase system can be greatly reduced.
Owner:HUAXIANG XIANGNENG TECHNOLOGY CO LTD

An electrified railway co-phase traction power supply system and control method thereof

The present invention discloses a co-phase traction power supply system for electrified railways and a control method thereof. The co-phase traction power supply system includes a traction transformer, a compensating matching transformer, a co-phase compensation device, an energy storage device, and a measurement and control device. The primary side of the traction transformer is connected to the three-phase high-voltage bus, and any two terminals of its secondary side are connected to the traction load; the primary side of the compensating matching transformer is connected to the secondary side of the traction transformer; the AC end of the co-phase compensation device is connected to the secondary side of the compensating matching transformer; the energy storage device is connected to the DC end of the co-phase compensation device; and the measurement and control device is connected to the co-phase compensation device and the energy storage device, respectively. Therefore, the present invention can not only realize co-phase power supply for the entire railway line and eliminate electrical phase separation, but also effectively realize the technical and economic optimization of co-phase power supply for electrified railways, thereby solving the power quality problem caused by the load of electric locomotives on electrified railways, which is mainly caused by the negative sequence of the three-phase system.
Owner:CHENGDU SHANGHUA ELECTRIC CO LTD

Grid-connected inverter and control method and device thereof, and phase-locked power supply system

The present disclosure relates to a grid-connected inverter and a control method and device thereof, and a phase-coherent power supply system. The grid-connected inverter comprises a power supply circuit and an inductive auxiliary voltage dividing circuit, wherein the power supply circuit and the inductive auxiliary voltage dividing circuit are connected; the grid-connected inverter is configured to boost the output voltage of an alternating current power supply; the power supply circuit comprises at least one single-phase power supply circuit, wherein each single-phase power supply circuit is connected with the inductive auxiliary voltage dividing circuit. The present disclosure provides a common-ground inverter with reduced switch quantity, the inverter of the present disclosure has a boosting characteristic, and can be extended to a three-phase system while maintaining the common-ground characteristic of the inverter.
Owner:GREE ELECTRIC APPLIANCE INC OF ZHUHAI

Power distribution network three-phase power flow analytical solution calculation method based on restart

The invention relates to a power distribution network three-phase power flow analytical solution calculation method based on restart, and belongs to the field of power distribution network power flow estimation. The method comprises the following steps: taking a three-phase HELM as an initial starting model; a flexible three-phase HELM model is deduced in combination with a three-phase element model of the power grid, and the flexible three-phase HELM model is used as a load flow calculation model after restarting; based on slow convergence of the power flow and even falling into two phenomena of stagnation solution and power flow divergence, different power flow restarting strategies are provided, and a'bud solution 'state, namely a no-load state, of the algorithm is restarted and updated in a recursive solving process. According to the method, rapid and reliable calculation of the power flow can be realized in a large-scale and heavy-load power distribution network three-phase system; the power flow restarting mechanism can dynamically respond to different distribution network systems and specific conditions of a power flow solving process, the restarting opportunity is flexibly adjusted, and the universality is high; the power flow restarting mechanism provides related reference for convergence domain analysis of power flow calculation in a three-phase system.
Owner:STATE GRID FUJIAN ELECTRIC POWER CO LTD +2

Three-phase UPS system

A three-phase UPS system (1) comprises a rectifier (100) and a battery (200). The rectifier (100) has an input side (101) being connectable to an AC power system (2) to provide first input power and to the battery (200) to provide second input power to the rectifier (100). The rectifier (100) has an output side (102) to provide a DC output power in response to a power share of the first input power and the second input power. The rectifier (100) is configured to be controlled such that the power share is adjustable.
Owner:EATON INTELLIGENT POWER LTD

AC to ac mmc with reduced number of converter arms

This disclosure relates to an AC-to-ACMC (2) configured to connect between a three-phase AC system (10a) and a single-phase AC system (10b). The MMC includes at least four converter arms (5) connected in a ring to allow a circulating current (I0) to circulate within the ring through each of the at least four converter arms. Each arm includes a plurality of converter units (4) connected in series. The MMC also includes phase terminals (x, y) arranged in a ring between the at least four converter arms, such that each of the at least four converter arms is separated from an adjacent converter arm on either side of the ring by at least one of the phase terminals. The phase terminals include corresponding terminals (x1, x2, x3) for each of the three phases of the three-phase AC system and corresponding terminals (y1, y2) for each of the positive and negative conductors of the single-phase AC system.
Owner:HITACHI ENERGY LTD

A constant-voltage type three-phase capacitive wireless power transmission circuit and parameter design method

The application belongs to the technical field of electric power, and relates to a constant-voltage three-phase capacitor wireless power transmission circuit and a parameter design method. The three-phase capacitor wireless power transmission circuit comprises a high-frequency three-phase inverter, three LCL input resonance compensation networks, three compensation inductance and capacitor plates, three CLC output resonance compensation networks and a three-phase uncontrolled rectifier. In the parameter design method, firstly, actual requirements and circuit structure parameters are determined; secondly, compensation network constraints and gains are determined; and finally, considering parameter robustness and operation efficiency, the parameters are designed. Compared with a traditional single-phase CPT structure, the three-phase CPT structure has higher power transmission capacity, and the parameter design method effectively improves the robustness of the three-phase CPT system to parameter deviation, ensures constant voltage output in the entire load power range, and controls the output voltage deviation within ±5%.
Owner:HUNAN UNIV

Microinverters for use with renewable energy systems

An apparatus configured for use with an energy management system is provided and comprises a three-phase system connection comprising three power production wires and a neutral wire, the three-phase system connection configured to transpose the three power production wires so that multiple single-phase microinverters are equally distributed over the three-phase system connection and a power line communication (PLC) filter connected to the three-phase system connection and PLC signal wires which are transposed via the three-phase system connection and connected to the multiple single-phase microinverters, the PLC filter is configured to couple / decouple the PLC signal wires to / from the three power production wires to prevent shorting of the PLC signal wires during operation.
Owner:ENPHASE ENERGY INC

Contactor-based double-path power supply automatic switching device and control method thereof

The invention discloses a contactor-based two-way power supply automatic switching device and a control method thereof, the contactor-based two-way power supply automatic switching device comprises a main circuit, a main power supply (L1) and a standby power supply (L2) in the main circuit are respectively connected to a modified contactor KM1 and a modified contactor KM2, the main power supply (L1) is connected to an L1 / L2 / L3 input terminal (a three-phase system) or an NC (normally closed) main contact of the contactor KM1, and the standby power supply (L2) is connected to an NC (normally closed) main contact of the contactor KM2. The standby power supply (L2) is connected to a corresponding input terminal of the contactor KM2, and the output ends T1 / T2 / T3 of the two contactors are connected in parallel and then are connected to a load air switch; normally closed contacts of the contactors KM1 and KM2 are interlocked to ensure that only one contactor can be closed at any time so as to avoid short circuit of a power supply. The voltage states of the main power supply (L1) and the standby power supply (L2) are monitored in real time, when the main power supply is abnormal, the standby power supply is automatically switched, it is ensured that the load continuously obtains stable power supply, and the reliability of the power supply system is improved.
Owner:ZHUZHOU VEHICLE SECTION

Frequency response calculation method for three-phase system model of flexible direct current battery swap station

The invention discloses a frequency response calculation method and device for a three-phase system model of a flexible direct current battery swap station, a medium and equipment, and relates to the technical field of power systems. Splitting the three-phase system model of the flexible direct current battery swap station to obtain three subsystems; for any subsystem, determining a sub-relational expression among the branch input voltage, the relational matrix, the branch admittance, the node admittance and the node voltage; mapping the sub-relational expression into a total relational expression among the input voltage, the relational matrix, the branch admittance, the node admittance and the node voltage in the three-phase system model; substituting the node admittance matrix, the relation matrix, the branch admittance matrix and the branch input voltage of the three-phase system model into the total relation to obtain the node voltage of the three-phase system model; and determining the frequency response of the three-phase system model according to the node voltage of the three-phase system model. According to the method, the frequency response calculation efficiency of the three-phase system model of the flexible direct current battery swap station can be improved.
Owner:CSG EHV POWER TRANSMISSION +1

Phase sequence identification method, device and equipment of group three-phase system and medium

The invention discloses a phase sequence identification method, device and equipment for a group three-phase system and a medium, and belongs to the technical field of energy storage, and the method comprises the steps: pulling up an IOBus when the phase locking of a power grid succeeds; when the host carries out successful phase locking on the power grid, the IOBus is pulled up, and when the host judges that the IOBus outputs a high level, a low-level pulse signal is sent to the IOBus when the zero crossing point of the power grid is detected; judging the time when the IOBus outputs the low-level pulse signal as the time when the host crosses the zero point, and judging the time when the power grid crosses the zero point as the time when the target slave crosses the zero point by taking the time when the host crosses the zero point as a reference; and determining phase sequences corresponding to the host and the two slaves according to the time of the target slave and the host at the zero crossing point. By means of the method, the problems that in an existing three-phase system, the phase sequence recognition result of each single-phase inverter is not high in precision, and the phase sequence recognition result is prone to interference can be solved.
Owner:GOODWE TECHNOLOGIES CO LTD

Low-voltage three-phase metering balancing method and system

The invention discloses a low-voltage three-phase metering balancing method and system, and relates to the technical field of power systems, and the method comprises the following steps: collecting current and voltage signals of a low-voltage three-phase power system in real time; calculating power, power factor and load current electrical parameters of each phase; calculating the power difference of each phase, and judging the balance condition of each phase; if it is found that power imbalance exists between the phases, a balance adjustment process is entered; adjusting load distribution or voltage compensation to enable the three-phase system to reach a balanced state; and if the balance adjustment succeeds, the normal monitoring mode is recovered. By adjusting load distribution and voltage compensation, it is ensured that the system is always kept in a balanced state, the use efficiency of electric power resources is optimized, the equipment fault risk is reduced, manual intervention and maintenance cost are reduced, the stability, reliability and energy efficiency of the electric power system are improved, and the method is suitable for popularization and application. And a more intelligent and efficient solution is provided for power management.
Owner:STATE GRID SHANDONG ELECTRIC POWER CO QINGDAO HUANGDAO DISTRICT POWER SUPPLY CO

Optical storage three-phase system grid-connected circuit and method based on VSG control

The invention discloses an optical storage three-phase system grid-connected circuit and method based on VSG control, and relates to the technical field of optical storage micro-grid control. The running characteristics of the synchronous generator are simulated through the VSG technology, necessary rotational inertia and damping are provided for the power grid, and the stability of the power grid is improved under the condition that the new energy power generation permeability is increased by simulating the damping and rotational inertia of the synchronous generator; meanwhile, automatic power distribution can be achieved, the self-adaptive capacity of the power grid is enhanced, synchronous operation with the power grid can be achieved, and when the power grid breaks down or disturbs, the VSG technology can provide inertial support and reduce power oscillation of the power grid, so that the reliability of power supply is improved. According to the method, large-scale access of new energy is facilitated through application of the VSG technology, negative effects caused by low inertia and no damping characteristics of power electronic equipment can be solved, the adaptability of a power grid to the new energy is improved, and a new stable operation mechanism is provided for the power grid in the aspects of new energy grid connection and power grid modernization.
Owner:山东智源电力设计咨询有限公司 +2

Power conversion device and control method

To suppress fluctuation of neutral point potential in a wide operation region.SOLUTION: A power conversion device according to an embodiment of the present invention includes two power converters and a control unit. In each of the two power converters, a DC-side terminal is connected to a connection point between the first DC capacitor and the second DC capacitor connected in series, and an AC-side terminal is connectable to a three phase system. The control unit superimposes a predetermined first zero phase voltage value in one power converter of the two power converters on a voltage command value of each phase of the one power converter, imposes a limitation on a superimposition amount of the zero phase voltage value, and superimposes an exceeding first zero phase voltage value based on a first voltage value that cannot be superimposed due to the limitation on a voltage command value of each phase of the other power converter of the two power converters to obtain a voltage command value of each phase of the other power converter.SELECTED DRAWING: Figure 2
Owner:KK TOSHIBA +1

Fusing device and method for three-phase synchronous drop-out fuse

The invention relates to the technical field of power switches, and discloses a fusing device and method for a three-phase synchronous drop-out fuse, and the device comprises a top housing, the lower surface of the top housing is fixedly connected with a resistor assembly, the bottom end of the resistor assembly is fixedly connected with a pedestal, and the exterior of the lower side of the resistor assembly is fixedly connected with a supporting housing. The outer portion of the supporting shell is fixedly connected with an insulating support, the inner portion of the supporting shell is rotatably connected with a fuse tube, the outer portion of the fuse tube is slidably connected with a sliding sleeve, the lower surface of the top shell is fixedly connected with an adjusting assembly, and the outer portion of the lower side of the adjusting assembly is rotatably connected with a sliding rod. A fixing assembly is arranged outside the top end of the resistor assembly, and a protection assembly is arranged at the rotating connection position of the fuse tube and the supporting shell. Through the mutual cooperation of the sliding sleeve, the sliding rod and the adjusting assembly, when the fuse tubes fall due to abnormal current, the action of a single fuse tube can be synchronously transmitted to other two phases of a three-phase system, and the reliability and stability of circuit protection are improved.
Owner:XIANNING POWER SUPPLY COMPANY OF STATE GRID HUBEIELECTRIC POWER

Component phase determination method and component phase determination system of three-phase system

The embodiment of the invention provides a component phase state determination method and a component phase state determination system of a three-phase system, and belongs to the field of component numerical simulation. The method comprises the following steps: determining a gas-water initial phase equilibrium constant of each component according to a gas-oil initial phase equilibrium constant of each component in a three-phase system and a Henry law constant of a water phase; according to the physical property parameters of the three-phase system, the gas-oil phase equilibrium constant of each component and the gas-water phase equilibrium constant of each component, the phase equilibrium state of the three-phase system is determined; and under the condition that the three-phase system reaches phase equilibrium, according to the gas-oil phase equilibrium constant of each component and the gas-water phase equilibrium constant of each component, determining the molar percentage content of each component in the oil phase, the gas phase and the water phase. The component phase state determination method not only can calculate the molar percentage content of each component in an oil phase, a gas phase and a water phase, but also can simulate the influence of NaCl on the phase state and the disappearance process of the water phase.
Owner:CHINA PETROLEUM & CHEMICAL CORP +1

Transformer area line loss line positioning device and use method thereof

The invention discloses a transformer area line loss line positioning device and a use method thereof, and belongs to the field of power detection equipment. The upper end of the clip-on ammeter main body is connected with two shafts through bearings; each shaft is in key connection with a jaw; wherein the side surface of one jaw is provided with a button for controlling opening and closing of the jaw, and an elastic part for resetting the button is arranged between the button and the clip-on ammeter main body. Each shaft is in key connection with a gear, an arc-shaped groove is formed in the outer circle face of each shaft, and the outer side of each shaft is sleeved with a sleeve. The inner wall of the sleeve is fixedly connected with a limiting block in sliding fit with the arc-shaped groove. According to the utility model, not only can workers be prevented from electric shock, but also wires or a plurality of wires in a three-phase system can be fixed through the arc-shaped rod during use, and the direction and distance of the undetected wires can be changed through the gap between the arc-shaped plate and the limiting plate, so that the influence of a magnetic field generated by current in the undetected wires on a detection result is reduced; and more accurate reading is ensured.
Owner:MARKETING SERVICE CENT OF STATE GRID HEILONGJIANG ELECTRIC POWER CO LTD

A real-time calculation SVPWM method capable of eliminating PWM one-beat delay

The application provides a real-time calculation SVPWM method capable of eliminating PWM one-beat delay. According to the characteristics of SVPWM vector output, a vector with long enough duration is selected to be output at the starting moment of each beat, so as to ensure that no vector switching occurs within the calculation time, and to ensure that the system can complete calculation and update PWM instruction within the calculation time, so that the delay update of the PWM instruction is equivalent to the update at the sampling point. The application also provides a proper vector switching sequence and a duty cycle calculation method, so that the PWM strategy can reliably operate, and according to the voltage output law of the controller, a hysteresis loop and a lookup table are designed to determine the output vector at the starting moment of each beat. The application can ensure that the one-beat delay of the system is eliminated, and the modulation range is not lost, so that ideal three-phase system non-delay PWM is achieved.
Owner:NORTHWESTERN POLYTECHNICAL UNIV

Neutral point potential balance and common-mode voltage suppression method and device for three-level six-phase system

The invention discloses a neutral point potential balance and common-mode voltage suppression method and device of a three-level dual three-phase system, and belongs to the technical field of motor control. The method comprises the following steps: acquiring a target modulation wave, sorting reference voltages according to the magnitude, and dividing the reference voltages into six sectors; zero-sequence voltage is calculated according to the sorted reference voltage; according to the zero-sequence voltage, duty ratios of a high level, a zero level and a low level in a carrier period are calculated; obtaining a zero level duty ratio adjustment amount d0 through a PI controller, and subtracting the zero level duty ratio adjustment amount d0 from the zero level duty ratio of the non-clamping phase to obtain a PWM sequence of each phase; performing phase shifting on the PWM sequence of each phase according to a preset phase shifting strategy to obtain a target modulation wave; and comparing the target modulation wave with the carrier wave to generate a target PWM signal, and controlling the three-level inverter. The unbalance of the neutral point potential at the inverter side is suppressed, and the influence of the common-mode voltage is suppressed.
Owner:HUAZHONG UNIV OF SCI & TECH

Electrical energy transmission arrangement and coupling of two asynchronous three-phase systems

The invention relates to an electrical energy transmission arrangement (1) and to a method for coupling two asynchronous three-phase systems (2, 3, 12, 13, 14). The electrical energy transmission arrangement (1) comprises a converter (4), which is designed to generate a second three-phase AC voltage with an adjustable frequency from a first three-phase AC voltage, and has three converter units (15), which each have a three-phase coupling transformer (16) and a modular multilevel converter (17). The multilevel converter (17) of each converter unit (15) is connected on the input side to the three phases (A, B, C) of the first three-phase AC voltage via the three-phase coupling transformer (16) of the converter unit (15), has two output connections (U, V) on the output side, and is designed to generate a single-phase AC voltage between the output connections (U, V). The output connections (U, V) of the three multilevel converters (17) are connected to one another to form output-side phase connections (L1, L2, L3) of the converter (4) for the three phases of the second three-phase AC voltage.
Owner:SIEMENS ENERGY GLOBAL GMBH & CO KG

Three-level dual three-phase PMSM system FCS-MPC method based on multi-target decoupling optimization

The invention relates to a three-level dual three-phase PMSM system FCS-MPC method based on multi-target decoupling optimization, and belongs to the technical field of permanent magnet synchronous motor control. Aiming at the problem of incapability of synchronous optimization caused by multi-target coupling in the existing finite set model prediction control, a virtual vector set of low common-mode voltage and zero-harmonic components is constructed to suppress harmonic waves, common-mode voltage and switching frequency, and a balance factor is adjusted by combining a redundant virtual vector and a dead-beat controller to realize active balance of capacitor neutral-point voltage. And the periodic alternate switching frequency is reduced by adopting staggered PWM modulation. According to the invention, accurate tracking of the dq-axis current is realized, the common-mode voltage is reduced to Udc / 12, the phase current THD is lower than 13%, the switching frequency is less than or equal to 4.3 kHz, and the multi-objective optimization performance of the system is significantly improved.
Owner:CHONGQING UNIV

Photovoltaic power generation area electric energy quality optimization method based on three-phase HDT system

The invention discloses a photovoltaic power generation area electric energy quality optimization method based on a three-phase HDT system, and relates to the technical field of power distribution network electric energy quality optimization, and the method comprises the steps: constructing a three-phase hybrid distribution transformer system composed of a standard transformer, a power electronic converter, a bypass switch and an LC filter; based on the operation characteristics of the three-phase hybrid distribution transformer system, simulation testing is carried out on the voltage amplitude adjusting capability and the harmonic compensation capability of a power supply side of the three-phase hybrid distribution transformer system by using a simulation technology so as to verify the voltage adjusting capability of the three-phase hybrid distribution transformer system; and in combination with the voltage regulation capability of the three-phase hybrid distribution transformer system, the electric energy quality of the photovoltaic power generation area is optimized through the three-phase hybrid distribution transformer system. According to the invention, it is verified that the three-phase HDT system has good voltage amplitude and phase compensation capability and harmonic compensation capability, and a good foundation is laid for electric energy quality optimization application of the three-phase HDT system in a photovoltaic power generation area.
Owner:NINGBO TRANSMISSION & DISTRIBUTION CONSTR

A drive circuit for a three-phase system power switching device

The application provides a driving circuit for a three-phase system power switch device, the three-phase system comprises a power switch group corresponding to each phase, the power switch group comprises an upper bridge arm power switch and a lower bridge arm power switch, the driving circuit corresponds to the upper bridge arm power switch, the driving circuit comprises a capacitor voltage division circuit, a voltage stabilizing circuit and a push-pull driving circuit, the capacitor voltage division circuit is connected with two phases except the corresponding phase, the output end of the capacitor voltage division circuit is connected with the corresponding voltage stabilizing circuit, the push-pull driving circuit and the upper bridge arm power switch of the corresponding phase in sequence, direct power is taken from the three-phase power supply, and a stable direct current voltage is generated to reliably drive the power switch device. The application realizes efficient and reliable driving of the power switch device, and overcomes the limitations of the traditional driving circuit which depends on a heavy isolation transformer or a complex switch power supply.
Owner:STATE GRID HUNAN ELECTRIC POWER COMPANY LIMITED +2