1518 results about "Capacitor voltage" patented technology

The invention provides a modularized multi-level converter current control method based on feedforward analysis. The deviation between the direct-current side voltage and the reference value is stably monitored in real time based on the direct-current bus voltage, a first waveform signal is dynamically generated, and the direct-current side voltage fluctuation range is limited. According to the circulating current interphase voltage sharing, the dynamic deviation between the actual value and the rated value is calculated by collecting the capacitor voltage actual value of the bridge arm sub-module, and a second waveform signal is generated to balance the circulating current distribution of each phase of bridge arm. The loop current suppression based on feedforward analysis generates a third waveform signal to compensate for high-frequency loop current interference through real-time comparison of theoretical modeling and actual loop current components. In the modulation wave generation process, information in all aspects is integrated to accurately control the on-off state of the sub-module, so that the operation effect of the system is improved under the complex working condition, and the real-time performance and predictability of control are considered through combination of closed-loop adjustment and feed-forward compensation, so that the effectiveness of control is improved.

According to the SiC MOSFET global short circuit and overcurrent protection circuit and the control method thereof provided by the invention, when a short circuit fault occurs in the SiC MOSFET, the drain current ID is more than several times of the rated current of the SiC MOSFET. When a short circuit occurs, a transistor QDZ of the short circuit detection circuit is switched on by node voltage Vr of the resistance-capacitance filter circuit, a fault signal VFAULT is converted into a low level, grid voltage VGS output by the grid control unit is gradually converted into zero voltage from negative driving voltage VEE, and soft turn-off is performed on the SiC MOSFET; when an over-current fault occurs in the SiC MOSFET, drain current ID is higher than rated current, node voltage Vo of the resistance-capacitance filter circuit lasts for a long time, the maximum value of capacitor voltage Vch of the over-current detection circuit is higher than reference voltage Vref2, a fault signal VFAULT is converted into low level, grid voltage VGS output by the grid control unit is gradually converted into zero voltage from negative driving voltage VEE, and soft turn-off is performed on the SiC MOSFET. According to the invention, high-speed short circuit and over-current fault protection of the SiC MOSFET in all inductance regions of a commutation loop can be realized.

The invention relates to the technical field of inverter pulse width modulation, in particular to a neutral-point potential balance and low common-mode voltage modulation method and system based on an SVPWM inverter, and the method comprises the steps: determining a basic voltage vector based on different switching states of an NPC three-level inverter; respectively determining the midpoint current of each fundamental voltage vector, and determining the fundamental voltage vector causing midpoint potential deviation; combining with a large vector and a zero vector, and performing mode division of a single vector space region; determining an expected current according to the DC side capacitor voltage of the inverter, and constructing a target function based on the expected current; and performing region judgment according to the output synthesized voltage vector, determining a corresponding optimal division mode, obtaining each basic voltage vector of the synthesized voltage vector and a corresponding duty ratio, and determining a switching sequence to obtain a PWM wave. While the neutral-point potential balance and common-mode voltage suppression of the NPC three-level inverter are realized, the switching frequency of the inverter is effectively reduced, and the switching loss is reduced.

The invention discloses a current coordinated distribution and voltage optimization control method of a multi-network converter considering nonlinearity and negative sequence load. The method comprises the following steps: carrying out harmonic separation on three-phase load side current and three-phase capacitor voltage through feedforward compensation to obtain a fundamental wave positive sequence component, a fundamental wave negative sequence component and an h-order harmonic component; fundamental wave positive sequence active and reactive power are solved, and angular frequency and output voltage are respectively obtained through an active frequency regulator and a reactive voltage regulator; virtual impedance of a fundamental wave positive sequence, a fundamental wave negative sequence and a harmonic component is set, a multi-frequency-point virtual impedance voltage drop instruction is calculated, and a voltage reference instruction value is obtained by subtracting the multi-frequency-point virtual impedance voltage drop instruction value from the output voltage of the constructed network type converter; calculating a three-phase modulation wave signal based on the voltage reference instruction value, the capacitor voltage, the load side current, the inductor current and the DC voltage; and calculating a pulse signal of the switching device based on the three-phase modulated wave signal. The virtual impedance of the networking converter is set to be a negative value, the harmonic voltage drop on a common coupling point can be reduced, the sum of the virtual impedance and the actual impedance is adjusted to be a certain proportion, and the harmonic current of each order of the multi-networking converter can be distributed according to the proportion.

The present invention provides a method for cooperatively suppressing a common-mode voltage and current harmonics of coupled three-level inverters, comprising: based on amplitude and phase angle of reference voltage vector, determining sector and region in which the reference voltage vector is located; selecting four basic voltage vectors with low common-mode voltage amplitudes to synthesize the reference voltage vector; writing volt-second balance equation based on selected basic voltage vectors, and calculating duty cycles thereof; and based on sector and region in which reference voltage vector is located, set value of voltage difference across capacitors on direct current side, and actual value of voltage difference across capacitors on direct current side, (1) updating duty cycles of basic voltage vectors, to realize separate control of capacitor voltage; and (2) designing and converting switching sequence into PWM drive signal of power switch, to control the coupled three-level inverter to operate.

The invention relates to a power electronic technology, and aims to provide a network construction type SVG control method suitable for multiple power grid strengths. Comprising the following steps: obtaining a power grid angular frequency based on a phase-locked loop principle, and obtaining an internal frequency of SVG equipment based on capacitor voltage-frequency droop control; multiplying the two angular frequency values by respective corresponding power grid intensity adaptation parameters to obtain a phase-locked loop reference angular frequency and a droop reference angular frequency, and performing integral calculation on the phase-locked loop reference angular frequency and the droop reference angular frequency and a power grid nominal angular frequency to obtain a phase angle; and finally, a switching signal is generated in an SVG control link, so that control of SVG equipment is realized. According to the method, a more stable reference power grid phase angle is obtained, the broadband oscillation instability condition possibly occurring under a strong power grid can be suppressed, the network-forming SVG can work under different power grid intensities, and the operation stability is improved; the method can enhance the power grid synchronization stability of the network construction type control under the strong power grid, and is suitable for different system conditions.

The invention discloses an MMC sub-module fault processing method, device and equipment and a storage medium, and the method comprises the steps: obtaining the capacitor voltage value of a sub-module of an MMC and the bridge arm current value of the sub-module, the MMC comprises six bridge arms of three phases, each bridge arm comprises a plurality of sub-modules, the capacitor of each sub-module is connected with an equivalent series resistor in series, and further, the equivalent series resistor is connected with the capacitor voltage value of the sub-module of the MMC; the resistance value of an equivalent series resistor in the sub-module is monitored through the capacitor voltage value and the bridge arm current value, if the resistance value of the equivalent series resistor is higher than a preset resistance value, it is determined that the capacitor of the sub-module fails, fault-tolerant control is carried out on the sub-module through a voltage-sharing and circulating current suppression algorithm, a three-phase switching signal is output, and the three-phase switching signal acts on the MMC. Therefore, the circulating current fundamental frequency component and the double frequency component caused by fault-tolerant control after the fault can be eliminated through the circulating current suppression strategy, the effect of circulating current suppression is achieved, and the stability of system fault operation is improved.

The invention relates to the technical field of MMC sub-module balance control, and discloses a capacitor voltage balance control method and system for an MMC sub-module, and an MMC, and the method comprises the steps: judging whether a bridge arm is in a near-zero current risk region or not according to the direction of the current of the bridge arm in each valve control period; if the bridge arm is not in the near-zero current risk area, judging whether the bridge arm is in a modulating wave extreme value risk area or not according to the bridge arm modulation voltage instruction; if the bridge arm is in a near-zero current risk area or a modulating wave extreme value risk area, a first switching strategy is adopted; and if the bridge arm is not in the modulating wave extreme value risk area, a second switching strategy is adopted. According to the invention, the switching frequency is effectively reduced and the narrow pulse phenomenon of the sub-module is eliminated through the judgment of the frequent switching risk area and the corresponding switching strategy, meanwhile, the module alternation probability is effectively reduced through the sorting switching strategy based on the dynamic additional factor, and the fluctuation range of the module voltage is limited within the required range, so that the switching efficiency is improved. And the operation safety and stability of the MMC are ensured.

An energy self-balancing flexible direct-current converter valve, a control method, and a direct-current system, which relate to the technical field of power transmission and distribution networks. The converter valve comprises three phase units, and each phase unit comprises an upper leg and a lower leg. The upper legs and the lower legs each comprise a plurality of full-bridge energy self-balancing submodules and a plurality of half-bridge energy self-balancing submodules. Each of the full / half-bridge energy self-balancing submodules is an optimized MMC submodule comprising an energy self-balancing circuit. The energy self-balancing circuit is composed of a power electronic switch and an energy dissipation resistor connected in series, and is used for dissipating surplus energy when an overvoltage early warning occurs for the capacitor voltage of the submodule. The present application, without affecting the operational logic of conventional converter valves and at low costs, can solve the technical problem of surplus power not being dissipated promptly due to faults occurring in a direct-current power transmission system in a new energy islanded ultra-long-distance direct-current delivery scenario. Meanwhile, temporary energy stored in the capacitors of the optimized MMC submodules can be fully utilized, reducing the waste generated by surplus power dissipated as heat.

The invention discloses a construction method and a modulation method of a three-port multi-frequency MMC topology based on bridge arm multiplexing, and relates to the technical field of power electronics. The construction method comprises the steps that sub-modules of a traditional double-bridge-arm MMC are integrated and optimized into a three-bridge-arm structure through a current conversion branch, independent energy interaction of three ports is achieved through an auxiliary bridge arm, multi-frequency operation modes of power frequency, frequency division, direct current and the like are supported at the same time, and therefore the utilization rate of the bridge arm sub-modules is increased, and the energy utilization rate of the MMC is increased. And the overall size and the manufacturing cost of the converter are reduced. Based on three-port multi-frequency coordination control and power balance requirements, a modulation method of the topological structure is provided, a multi-frequency coordination modulation strategy is adopted, frequency offset is performed through an auxiliary bridge arm to reduce cross interference of port frequency, and output waveform quality is improved through multi-objective optimized capacitor voltage balance control. And meanwhile, direct-current side faults are effectively eliminated by means of the auxiliary bridge arm.

The invention discloses an ISOP type medium-voltage DC converter LLC module fault diagnosis method and device, a medium-voltage DC power supply system and a storage medium. Comprising the following steps: monitoring an input capacitor voltage, an input current, an output voltage and an output current of each LLC module port; according to the output voltage and the output current, judging whether a fault condition of the ISOP type medium-voltage direct-current converter is met or not; under the condition that it is judged that the fault condition is met, the difference between the input capacitor voltage change rate, the input voltage amplitude and the input current amplitude of each LLC module is calculated; according to the input capacitor voltage change rate, the input voltage amplitude and the input current amplitude, the LLC module with the switch tube open-circuit fault or the input capacitor aging fault in all the LLC modules is judged. According to the scheme of the invention, the online detection and positioning of the fault LLC module are completed by using the difference between the electrical quantity amplitudes and the change rates of the LLC modules, and the phenomenon of misdiagnosis caused by large input voltage fluctuation is avoided.

The invention discloses a particle swarm and non-linear programming hybrid optimization VSG adaptive control method and system, and relates to the technical field of virtual synchronous generator control, and the method comprises the steps: collecting a filter inductor current and capacitor voltage signal, outputting an instantaneous active power and a reactive power, constructing a small signal dynamic model of a VSG, and building a parameter mapping relation; setting a constraint range based on the parameter mapping relation in combination with a second-order oscillation modal stability criterion of the power system; constructing a hybrid optimization algorithm according to the constraint range, and outputting steady-state data; constructing a two-dimensional threshold criterion system, and cooperatively generating a voltage reference value through a speed regulator and a controller; the voltage reference value is compared with the actual output voltage, and the inverter output is driven through PI control and PWM modulation. The method has the beneficial effects that the parameter optimization precision is improved, the stability of the system is guaranteed, and the calculation efficiency of the algorithm is improved.

A system includes: an alternating current (AC) to direct current (DC) converter (AC-DC converter) including a bulk capacitor, the AC-DC converter connectable to a line voltage; a DC to DC converter (DC-DC converter) connected to the AC-DC converter, the DC-DC converter including: one or more transformers having a secondary side connectable to a battery, and a bridge rectifier connected to the secondary side of the one or more transformers, the bridge rectifier including a bridge rectifier switch; and one or more controllers configured to control an operation of the bridge rectifier switch to control a voltage of the bulk capacitor.

The invention discloses a SiC MMC sub-module capacitor voltage fluctuation suppression method and system, and belongs to the technical field of electronic power. According to the analysis result of the optimal broadband harmonic circulation injection boundary and number of times of the SiC MMC sub-module, a sub-module capacitor voltage fluctuation optimization model for simultaneously injecting second, fourth and eighth harmonic circulation and third harmonic voltage is determined, and the characteristic of higher control bandwidth of the SiC MMC can be fully utilized; by solving a submodule capacitor voltage fluctuation optimization model, the amplitudes and phases of reference values of second, fourth and eighth harmonic circulation needing to be injected and the amplitude and phase of corresponding third harmonic voltage are determined, then the second, fourth and eighth harmonic circulation is injected, and the third harmonic voltage injection is combined to realize broadband harmonic combined injection. The capacitance voltage fluctuation of the sub-module is reduced, the capacitance voltage fluctuation suppression method for the SiC MMC sub-module is realized, and the suppression effect is relatively high.

The invention relates to the technical field of modular multilevel converters, and provides an MMC fault diagnosis method, system and device based on a sorting voltage-sharing algorithm. Comprising the steps that according to measurement data of the modular multilevel converter, a theoretical value and an actual value of bridge arm voltage of the modular multilevel converter are obtained through calculation, the theoretical value and the actual value are compared with a first alarm threshold value, and a corresponding bridge arm fault and a fault type are determined; calculating the number of fault sub-modules according to the bridge arm voltage actual value and the bridge arm voltage theoretical value; judging the switching number of the fault bridge arm sub-modules, and controlling and adjusting the bridge arm sub-modules to be switched on according to the fault type and the number of the fault sub-modules; and calculating a capacitor voltage minimum difference value, comparing the capacitor voltage minimum difference value with a second alarm threshold value, and determining a fault sub-module. According to the multi-tube fault diagnosis method, the problem that the fault positioning performance is poor under the light load working condition is solved, and the sub-module positioning performance in the full power range is improved.

The invention relates to the technical field of energy storage system grid-connected control, and particularly discloses a two-stage coupling type battery energy storage grid-connected converter model prediction control method and device, and the method comprises the following steps: S1, constructing a two-stage coupling type battery energy storage grid-connected converter single-machine two-order composite model; s2, according to the single-machine dual-order composite model, constructing a prediction equation of the output current and the capacitor voltage of the inverter; s3, constructing a unified cost function of the output current and the capacitor voltage of the inverter; s4, predicting the switch state combination of all the switch tubes, and calculating the value of a corresponding unified cost function; and S5, selecting the switch state combination with the minimum uniform cost function value as the optimal switch state of all the switch tubes, and carrying out on-off control on the switch tubes. According to the invention, through unified modeling and control optimization, the dynamic response capability and the voltage stabilization performance of the energy storage grid-connected converter are improved.

Disclosed in the present invention is a state of charge (SOC) balancing method for an energy storage MMC based on capacitor voltage correction, comprising the following steps: acquiring important parameters such as the SOCs of energy storage units and current directions of bridge arms in an energy storage MMC; calculating SOC average values of phase units, of the bridge arms, and of three phases of energy storage units; calculating the inter-phase SOC imbalance degree, the inter-bridge arm SOC imbalance degree, and the inter-submodule SOC imbalance degree, obtaining an inter-phase power deviation, an inter-bridge arm power deviation, and an inter-submodule voltage deviation by means of a proportional controller, and calculating a submodule energy storage power reference value and submodule corrected capacitor voltages; calculating the duty cycle of a switching device in a bidirectional DC / DC converter; and sorting the submodule corrected capacitor voltages, and on the basis of the charging / discharging state of submodule capacitors, determining submodules to be connected. The present invention can realize SOC balancing of energy storage MMCs, and reduces the number of bidirectional DC / DC converter controllers, thereby improving the SOC balancing efficiency and the capacity utilization rate of energy storage units.

This invention discloses a method and system for suppressing capacitor voltage fluctuations in SiC MMC submodules, belonging to the field of electronic power technology. Based on the analysis results of the optimal broadband harmonic circulating current injection boundary and order for SiC MMC submodules, an optimized model for submodule capacitor voltage fluctuations is determined that simultaneously injects 2nd, 4th, and 8th harmonic circulating currents and 3rd harmonic voltages, which can fully utilize the higher control bandwidth characteristic of SiC MMC. By solving the optimized model for submodule capacitor voltage fluctuations, the amplitude and phase of the reference values ​​of the 2nd, 4th, and 8th harmonic circulating currents to be injected, as well as the amplitude and phase of the corresponding 3rd harmonic voltage, are determined. Then, by injecting 2nd, 4th, and 8th harmonic circulating currents and jointly injecting the 3rd harmonic voltage, broadband harmonic joint injection is achieved, reducing the capacitor voltage fluctuations of the submodule and realizing a method for suppressing capacitor voltage fluctuations in SiC MMC submodules with high suppression effect.

The invention relates to the technical field of power electronic conversion and control, in particular to a control method of a three-level three-phase four-leg inverter and electronic equipment. The method comprises the following steps: acquiring a multi-phase first capacitor voltage and a multi-phase first inductor current; acquiring a second inductive current corresponding to a second bridge arm; determining a plurality of first modulation waves corresponding to the multi-phase first bridge arm according to the multi-phase first capacitor voltage and the multi-phase first inductor current; acquiring a positive half bus voltage and a negative half bus voltage; determining a plurality of first driving signal groups corresponding to the plurality of first modulation waves according to the positive half bus voltage and the negative half bus voltage; determining a second driving signal group according to the multi-phase first capacitor voltage, the second inductor current and the plurality of first modulation waves; and driving the corresponding first bridge arm according to each first driving signal group, and driving the second bridge arm according to the second driving signal group. The operation stability and safety of the distributed micro-grid system can be improved.

The invention provides a capacitor voltage transformer error online detection method and system, and the method comprises the steps: collecting a secondary output signal of a three-phase capacitor voltage transformer, and carrying out the data preprocessing; based on the collected data, constructing a deep neural network learning model based on a stacked auto-encoder, and extracting deep features of the data through multilayer nonlinear transformation to obtain reconstructed data; taking the original data and the reconstructed data as input data, respectively carrying out co-integration analysis, and calculating a co-integration matrix and an equalization error; combining the reconstruction data with the equilibrium error, constructing a composite statistical magnitude and calculating a statistical magnitude threshold value; and collecting online measurement data of the capacitor voltage transformer, calculating monitoring statistics and carrying out abnormity diagnosis. The technical problems that disturbance components and error information in measurement data are difficult to distinguish, non-linear and non-stationary components in measurement errors of the capacitor voltage transformer are difficult to analyze, and the online detection accuracy and real-time performance of the measurement errors are low are solved.

The invention provides an input voltage anomaly detection method, a protection method and a control circuit. The control circuit comprises a voltage-current conversion circuit, the input end of which is coupled with the power switch for obtaining the terminal voltage of the power switch; the first capacitor is coupled to the output end of the voltage-current conversion circuit; the comparison circuit is used for comparing the first capacitor voltage with a reference signal and providing an input voltage anomaly detection signal; and a switch control circuit which controls the power switch based on the output of the comparison circuit and starts input voltage abnormality protection when the input voltage abnormality detection signal is valid. The control circuit provided by the invention can realize the anomaly detection of the input voltage based on the terminal voltage of the power switch, can reduce the use of pins, simplifies a peripheral circuit, reduces the system cost, and accelerates the protection response speed.

The invention provides an electric energy quality on-line monitoring device and a cloud platform cooperation system, and relates to the technical field of electric energy quality management, and the device comprises a signal collection unit which obtains three-phase voltage and current signals in parallel through a Rogowski coil and a capacitive voltage divider; the event detection unit is used for synchronously executing harmonic spectrum analysis and transient event capture by adopting a parallel processing architecture realized by an FPGA (Field Programmable Gate Array); the edge processing unit is connected with the event detection unit, and is configured to encode the transient event features into a Gramer angle field image and compress steady state data into feature vectors; the multimode communication unit comprises a 4G / 5G wireless module and an optical fiber Ethernet interface; and the strategy execution interface outputs a treatment instruction to the compensation device through the D / A converter and the current loop. Through collaborative innovation of the device and the cloud platform, the power quality monitoring and treatment efficiency is remarkably improved.

The invention provides a method and device for discharging residual charges of an air conditioner and the air conditioner. The air conditioner at least comprises a capacitor charging control circuit, a bus capacitor circuit, a fan driving circuit, a main control chip and a fan load. The discharging method comprises the steps that the main control chip responds to a bus capacitor discharging instruction and outputs a control signal used for controlling a capacitor charging control circuit to be disconnected; and obtaining a capacitor voltage value of a bus capacitor in the bus capacitor circuit, and controlling the fan driving circuit to drive the fan load to work through the obtained capacitor voltage value. According to the invention, rapid and efficient discharge of the bus capacitor can be realized, and the hardware cost and the system complexity are reduced on the premise of not influencing the working efficiency of the air conditioner.

The invention discloses a current harmonic suppression method, device and equipment of a T-type three-phase three-level inverter and a readable storage medium, and relates to the technical field of power electronics. Comprising the steps of obtaining an upper capacitor voltage and a lower capacitor voltage of the T-type three-phase three-level inverter, and determining a target control set according to a relation between the upper capacitor voltage and the lower capacitor voltage; for each candidate vector voltage in the target control set, calculating a cost value corresponding to each candidate vector voltage; and taking the candidate vector voltage corresponding to the minimum cost value as a target vector voltage. According to the method provided by the invention, the effective suppression of the current harmonics of the T-type three-phase three-level inverter is realized.

The invention discloses a three-level flexible excitation dynamic regulation and control method and system for a large-scale hydroelectric generating set, and relates to the technical field of flexible excitation control of the large-scale hydroelectric generating set, and the method comprises the steps: setting a DC bus voltage, and initializing a mapping relation between a capacitor voltage and an excitation output level; collecting operation parameters of a machine end, constructing a disturbance identification model and outputting a disturbance level; the excitation voltage output gear is set according to the disturbance level, the capacitor voltage difference is controlled, and dynamic voltage sharing is achieved by modulating the midpoint duty ratio. According to the method, through setting a bus target voltage and constructing excitation voltage output mapping, in combination with a disturbance level identification mechanism and a dynamic voltage-sharing strategy, closed-loop linkage of disturbance perception-voltage regulation-voltage difference control is realized. According to the method, the identification precision of the system on light disturbance and strong disturbance is effectively improved, the voltage stability and capacitance symmetry of the excitation system are enhanced, the overshoot risk is reduced, and the control robustness and safety of the system under extreme working conditions are improved.

The invention is suitable for the technical field of flexible power distribution of a power system, and discloses a modular multilevel converter multi-objective optimization method, system and device based on model predictive control and space vector modulation, and a medium. Obtaining an output current reference value and a circulating current reference value; obtaining a reference voltage vector based on the output voltage reference value, and screening out a plurality of groups of redundant voltage vector sequences through a space vector diagram; performing performance evaluation through rolling optimization by combining each redundant voltage vector sequence with a multi-target cost function to obtain an optimal voltage vector sequence; and on the basis of the optimal voltage vector sequence and the corresponding duty ratio, a switching signal for driving each sub-module switching device of the MMC is generated, and multi-target cooperative control is realized. The three targets of reference output current tracking, circulating current suppression and sub-module capacitor voltage balance are met, and the dynamic response capability, efficiency and reliability of MMC system operation are comprehensively improved.

An electronic device comprising: a charger integrated circuit configured to perform a buck converting operation based on an input voltage applied to a first node thereof to generate an output voltage output to a second node thereof, wherein the charger integrated circuit includes: a power switching circuit including a flying capacitor; a current sensing circuit that includes an inductor; and a control circuit that includes: a compensation circuit that is configured to compensate an inductor current value that is sensed from the current sensing circuit; an error voltage select circuit that is configured to generate a minimum error voltage based on feedback signals; and a comparison circuit that is configured to control a voltage of the flying capacitor, wherein the control circuit is configured to generate a control voltage by modifying the inductor current value based on the minimum error voltage and provide the control voltage to the comparison circuit.

The invention discloses an AI feedback system for monitoring opening and closing time of a switch in real time, which relates to the technical field of electrical variable measurement, and comprises a data acquisition module for acquiring three types of data in real time, pre-processing the data, marking the closing time by a central calculation processing module, comprehensively processing the data to obtain a copper scale interference model, and judging whether the copper scale interference model is interfered or not according to the copper scale interference model; the opening speed is adjusted, the opening moment is marked, the opening and closing time is calculated, and the early warning feedback module is called for early warning and AI feedback in case of abnormality. According to the method, multi-dimensional data are collected in real time to construct a copper scale interference model, when interference is detected, capacitor voltage is automatically increased to accelerate opening, compensation opening time is prolonged, equipment short circuit is avoided, the method is more real-time and self-adaptive compared with a traditional scheme, arc light and frequency parameters are comprehensively calculated, historical and real-time data are analyzed in combination with AI, early warning is carried out in the case of abnormity, and an adjustment strategy is optimized. Decision support is provided through a visual chart, whole-process intelligent management is achieved, and the safety and reliability of equipment are improved.

A multilevel power converter includes a plurality of switches, a first DC link capacitor, a second DC link capacitor, and one or more processors configured to: generate, for a duty cycle of the multilevel power converter, a pulse width modulated pulse pattern in accordance with a reduced common mode voltage scheme; modify the pulse width modulated pulse pattern to render a modified pulse pattern; and cause the plurality of switches to implement the duty cycle based at least in part on the modified pulse pattern to render a common mode voltage pulse to balance voltages at the first DC link capacitor and the second DC link capacitor.

The invention discloses a two-degree-of-freedom prediction control method of an LCL filtering type three-phase grid-connected inverter system, and belongs to the field of power electronic converter control. A prediction control reference instruction is obtained by sampling parameters of inverter side current, capacitor voltage, network side current and power grid voltage at the moment k, and a continuous and discrete model of an LCL filtering type three-phase grid-connected inverter system is established; designing a control function based on a grid-side current reference tracking error and a gradient thereof, and establishing a prediction model; constructing a prediction cost function based on a control function, and obtaining a prediction control reference instruction by using a minimum value of the prediction cost function; and determining an optimal voltage vector and an action duty ratio according to the prediction control reference instruction, generating a control pulse signal according to a symmetrical five-section pulse mode, and acting on each switching tube in the inverter to realize prediction control of the LCL filtering type three-phase grid-connected inverter system. The method is simple in step, convenient to use, constant in switching frequency and good in stability.