4045 results about "Voltage drop" patented technology

To enable accurate estimation of a degree of deterioration of a secondary battery with a metal lithium layer on an anode.SOLUTION: A battery deterioration estimation device comprises a current measurement part, a voltage measurement part, a calculation part, and an estimation part. The current measurement part measures a discharge current of a secondary battery at predetermined timing immediately after the start of discharge of the secondary battery. The voltage measurement part measures a drop voltage that is a difference between a voltage of the secondary battery before the start of discharge and a voltage of the secondary battery at the predetermined timing. The calculation part calculates an internal impedance of the secondary battery at the predetermined timing from the measured discharge current and the measured drop voltage. The estimation part estimates a degree of deterioration of the secondary battery from the calculated internal impedance.SELECTED DRAWING: Figure 1

The invention discloses an automatic anchor point searching and processing method for grid-connected test data of a photovoltaic inverter, and belongs to the technical field of automatic test of a power system. According to the method, a three-phase voltage and current signal output by a power grid simulator and an inverter power instruction signal are aligned through a high-precision time synchronization device; wavelet transform multi-scale noise reduction and moving average filtering combined preprocessing is adopted to improve the signal-to-noise ratio; identifying a voltage zero crossing point candidate set, a drop starting point candidate set and a recovery termination point candidate set based on a self-adaptive dynamic threshold value; transient energy characteristic verification is introduced for a voltage drop starting point; effective anchor points are confirmed through time window association of power instruction step changes. According to the method, the problems of low efficiency of manual key event point identification, misjudgment caused by noise interference, grid event and inverter response time sequence correlation missing and the like are solved, and the automation degree of test data analysis, anchor point positioning precision and control response time sequence analysis reliability are remarkably improved.

The invention discloses a network construction type VSG output power decoupling method based on voltage signal composite feedforward, relates to the technical field of power electronic control, and provides a network construction type converter grid-connected system and a method for realizing converter output power decoupling through converter output voltage signal composite feedforward for network construction type VSG power synchronous control. Comprising a network construction type VSG power control module, a power grid parameter detection unit, a line impedance observer, a virtual impedance voltage drop feedforward loop and a voltage signal secondary feedforward loop. According to the composite feed-forward control strategy, virtual impedance and voltage amplitude and power angle compensation are combined, the coupling effect of active power and reactive power is remarkably weakened, efficient decoupling is achieved, and the method is suitable for a complex power grid environment.

The invention relates to the technical field of cylindrical lithium ion battery production, and discloses a method for detecting insufficient welding of a cylindrical lithium ion battery, and the method comprises the following steps: S1, appearance inspection; s2, initial internal resistance benchmark test; s3, applying a short-time large-current pulse to the battery by using a pulse generator, simulating an actual load condition, and recording an instantaneous voltage drop and current response curve of the voltage of the battery end during the pulse period; s4, performing infrared thermal imaging identification and data processing; s5, learning the picture and establishing a model; s6, comparing the test picture and the data with the model; s7, dynamic internal resistance calculation; s8, cold solder joint query and sorting processing; and S9, retesting the electrical performance. According to the invention, the technologies of dynamic internal resistance measurement, nondestructive X-ray or ultrasonic detection, rate discharge test and the like are adopted, so that efficient, accurate and nondestructive detection of the cold solder joint of the cylindrical lithium ion battery is realized, and the production efficiency and the detection precision are remarkably improved.

The invention discloses a control method for improving the utilization rate of renewable energy sources in real time, particularly relates to the technical field of voltage collapse protection of a direct-current power distribution network, and is used for solving the problems of voltage collapse spreading and renewable energy source utilization rate reduction caused by photovoltaic sudden drop. The method comprises the following steps: monitoring photovoltaic output, bus voltage and load current in real time; predicting a voltage collapse spreading path; identifying an active migration source according to the time sequence difference between the voltage drop and the load current abrupt change; calculating a current increment upper limit of the active migration source cluster; generating a cross-region compensation instruction based on the current increment and the energy storage adjustable power; issuing a compensation instruction to the energy storage unit and synchronously locking the current regulation authority of the active migration source; through dynamic coupling of collapse path prediction and migration source identification, cooperative control of cross-regional power reverse compensation and local load behavior freezing is realized, voltage collapse chain propagation is blocked, and the photovoltaic local consumption rate is improved.

A system includes: an AC-DC converter; and a DC-DC converter, the DC-DC converter including: a first high voltage buck-boost converter having a secondary side connectable to a first high voltage battery; a second high voltage buck-boost converter having a secondary side connectable to a second high voltage battery; a first low voltage buck-boost converter having a secondary side connectable to a first low voltage battery; a second low voltage buck-boost converter having a secondary side connectable to a second low voltage battery; and one or more transformers having a primary side connected to the AC-DC converter and a secondary side connected to each of a primary side of the first high voltage buck-boost converter, a primary side of the second high voltage buck-boost converter, a primary side of the first low voltage buck-boost converter, and a primary side of the second low voltage buck-boost converter.

The invention relates to the technical field of PWM control, and discloses a high-precision PWM dead zone effect compensation method and system. The method comprises the following steps: carrying out differential sampling and signal conditioning on PWM output current to obtain a current sampling value; the driving signal is input into an FPGA state judgment module for state conversion analysis, and switch state information is obtained; performing dead zone characteristic quantity extraction based on the current sampling value and the switch state information to obtain a dead zone effect influence factor; according to the dead zone effect influence factor, compensation coefficient calculation is carried out in a piecewise linear mode, a real-time compensation value and a predicted compensation value are obtained, the real-time compensation value and the predicted compensation value are used for compensating dead zone position voltage drop in a PWM output voltage waveform, the real-time compensation value is used for current period compensation, and the predicted compensation value is used for next period compensation presetting. And high-precision PWM dead zone effect compensation is realized. According to the method, accurate calculation and dynamic prediction of the compensation value are realized, the compensation adaptability is improved, and finer compensation control is realized.

The invention discloses an IGBT junction temperature real-time decoupling modeling method and system based on dynamic electric heating compensation, and relates to the technical field of state monitoring of power electronic devices. At present, junction temperature estimation is not accurate due to IGBT on-state voltage drop measurement distortion and chip internal thermal gradient in a high-voltage environment. The method comprises the following steps: in an offline stage, constructing an ideal electrothermal characteristic database of an IGBT, a dynamic temperature gradient compensation database in a chip and Foster thermal network model parameters; in the on-line stage, synchronous sampling and preprocessing are carried out on IGBT module operation parameters; combining online real-time parameters with an offline database by using an adaptive Kalman filter, and iteratively and cooperatively estimating the real-time junction temperature and loss of the IGBT; and finally, outputting and applying the estimated accurate junction temperature and loss data. According to the technical scheme, the hot spot effect in the chip is accurately decoupled, the junction temperature estimation precision and the robustness of online monitoring are improved, and core data support is provided for fine thermal management and early fault early warning of the flexible direct current converter valve.

The invention provides a network construction type photovoltaic energy storage control system and method for improving the supporting capacity of a power grid. The system comprises a data sampling module, a reference power generation module, a VSG module, a voltage feed-forward compensation and virtual impedance control module, a voltage and current closed-loop control module and a PWM generation module. According to the invention, modeling is carried out on a network construction type photovoltaic energy storage control model, then virtual impedance is introduced into VSG reactive voltage control, and a power grid voltage feed-forward compensation model is provided according to a vector diagram, so that the value of the virtual impedance is determined to weaken the influence of voltage drop when a power grid fails and suppress overcurrent. The problem that a photovoltaic energy storage face is insufficient in low-voltage ride-through capacity is solved.

The invention discloses a single storage battery internal resistance on-line measurement method, which relates to the technical field of battery detection and comprises the following steps: S1, establishing a dynamic load disturbance model of a storage battery; s2, extracting effective voltage drop component data from the noise signal by adopting an adaptive filtering method; s3, calculating equivalent internal resistance by using a complex impedance calculation method; s4, performing multi-scale internal resistance evolution analysis based on the calculated equivalent internal resistance; and S5, based on multi-scale internal resistance evolution analysis, performing fault early warning on internal resistance abnormity. According to the on-line measurement method for the internal resistance of the single storage battery, high-precision on-line measurement of the internal resistance of the single storage battery is realized through construction of a dynamic load disturbance model, multi-scale internal resistance evolution analysis and fault early warning based on the internal resistance. Compared with the prior art, the method can accurately capture the influence of the load change on the internal resistance, utilizes the multi-scale internal resistance evolution analysis to early warn the internal resistance abnormity in advance, and improves the health management capability in combination with the multi-scale analysis.

The invention relates to the technical field of remote monitoring, in particular to a remote monitoring system for power equipment, which comprises a load lag mapping module, a voltage drop rate identification module, a temperature control abnormity judgment module, a task energy consumption optimization module and a scheduling priority ordering module. According to the method, trend deviation is identified by extracting key sections of load and temperature change, an abnormal propagation path is constructed by combining continuity and directivity of a voltage change rate, an association relationship between a diffusion chain and nodes is determined, and a fault path with a time sequence recursion characteristic is extracted based on load change difference in a temperature rise process. According to the method and the system, the task type, the energy consumption trend and the communication requirement are combined to screen nodes with scheduling value, a scheduling list is dynamically generated, the response priority is synchronously adjusted, and efficient overall planning of remote monitoring node management and self-adaptive optimization of a scheduling strategy are realized.

The invention relates to a power electronics and energy storage technology, and aims to provide a medium-voltage uninterruptible power supply system based on cascade super-capacitance energy storage and a control method. According to the system, a cascade super-capacitance energy storage module with a three-phase structure is connected between an isolation reactor and a load side switch through a filter reactor and is used for stabilizing the voltage of a load bus; according to the invention, operations of adaptive power reference calculation, voltage phase control and voltage amplitude stable control are carried out; according to the method, the over-capacitance wide voltage operation characteristic is fully considered, and the control on the over-capacitance charging and discharging process is adaptively adjusted according to the power grid fault state and the over-capacitance voltage deviation, so that the system can provide the required power support when the fault occurs, stable energy supplementation is performed after recovery, the risks of over-capacitance voltage out-of-limit and the like are favorably avoided, and the system reliability is improved. And the effectiveness of energy management and the stability of the system are improved. And during a power grid fault period, the load voltage is recovered to be close to a rated value in a short time, voltage drop and overshoot are reduced, and the response speed and the voltage supporting capability of the system are enhanced.

The invention relates to a high-precision temperature sensor based on complementary dynamic element matching and a zoom analog-to-digital converter and a working method, and belongs to the technical field of sensor improvement, and the sensor comprises an analog front end, an analog-to-digital converter, a digital rear end and a control logic. An improved chopping technology is adopted, and one clock signal is adopted to control two sub operational amplifiers, so that the output stability and precision of the analog front end are improved. A complementary dynamic element matching technology is utilized, errors caused by voltage drop at the two ends of a switch are reduced, the influence of channel charge injection is counteracted, a scaling type analog-to-digital converter design is provided for an analog-to-digital conversion part, and balance among power consumption, speed and precision is achieved. According to the method, a 10-bit successive approximation register analog-to-digital converter is used for measuring a numerical value and a change trend, and the numerical value and the change trend are analyzed, so that the expression effects of a current mirror structure, a transistor, a filter and the like are evaluated, the aging of the transistor is found in advance, and a clear direction is provided for future design improvement.

A low voltage ride through control method for a grid-forming inverter based on dynamic internal potential adjustment comprises the following steps: detecting a voltage per unit value of a grid-connected point in real time, and comparing the voltage per unit value with a threshold value to judge a voltage drop event and trigger low voltage ride through control; dynamically calculating active and reactive power reference values through a reactive compensation equation and an active current limiting equation according to the voltage amplitude and the power reference value before falling during the ride-through period; inputting the active reference value into a virtual rotor motion equation to generate a reference phase, and outputting a phase reference signal in combination with a dual-mode phase compensation controller; superposing the reactive reference value with the reference voltage through a reactive voltage regulating ring to generate a voltage amplitude reference signal; synthesizing an internal potential according to the phase and the amplitude reference signal, and obtaining an inductive current reference value through virtual impedance control and current amplitude limiting; and finally, a driving signal is generated through the current inner loop controller and the modulation module. According to the invention, overcurrent can be effectively inhibited, rapid reactive power support is provided, and synchronous stability and smooth transition in a fault period and a recovery process are ensured.

A method for configuring reactive power capacity of a power grid to which offshore wind power is connected on a large scale includes the following steps. Static voltage stability index of substations in a regional power grid to which the offshore wind power is connected on the large scale and at multiple points and relative dynamic voltage drop area index for an N-2 fault are calculated. Thus, weak nodes in voltage stability are located, thereby implementing a prediction of a risk to the voltage stability of the regional power grid. These nodes are used as candidate reactive power compensation configuration nodes. An objective function is established as the minimum total cost of reactive power compensation devices at the candidate reactive power compensation configuration nodes. A multi-type reactive power optimization configuration model including static voltage stability constraints, voltage stability constraints under faulty state, and other constraints is solved.

The invention provides a netlike inverter indifference control and PCC point voltage drop optimization system and method, a reactive power error feedback module generates a reactive power compensation amount according to received reactive power reference information and collected reactive power information, and combines proportional integral control to eliminate a steady-state error so as to realize static indifference control of reactive power; the PCC point voltage drop feedforward compensation module dynamically adjusts the output voltage amplitude of the inverter according to the deviation between the theoretical reference voltage and the actual voltage of the PCC point, and directly counteracts the voltage drop caused by the line impedance; the dynamic impedance compensation module dynamically adjusts an integral coefficient of a PI controller according to an impedance parameter of a multi-machine parallel circuit, adapts to different impedance scenes, and ensures reactive power equalization and voltage balance under multi-machine parallel connection; through cooperation of closed-loop feedback and feed-forward compensation, static indifference control is realized, power grid disturbance is resisted, and system reliability is improved.

The invention discloses a converter collaborative current limiting method based on adaptive virtual impedance and a power loop, and the method comprises the steps: firstly building an equivalent impedance model of a converter and a power grid, analyzing the steady-state and transient characteristics of fault current, and extracting key parameters for current limiting design; when it is detected that the voltage drop of the grid-connected point exceeds a threshold value, a self-adaptive virtual impedance link is automatically put into use, and virtual resistance and reactance values are dynamically calculated according to the variation amplitude of voltage or current, so that the virtual resistance and reactance values are proportionally adjusted along with the fault degree; and when the system voltage returns to normal, the virtual impedance automatically quits, and the control continuity is ensured. Then, the active and reactive power reference values are dynamically corrected according to the voltage drop depth, a power reference signal matched with the voltage amplitude is generated, it is guaranteed that power output does not exceed the limit, and the voltage supporting capacity is improved. Finally, real-time current-limiting control of the converter and stable operation of the system are realized on the premise of not switching the control mode through the synergistic effect of the virtual impedance ring and the power ring. The method has the advantages of being high in response speed, excellent in current limiting effect, good in control continuity and the like, and is suitable for fault current limiting and voltage support control of the grid-forming converter.

The invention relates to the field of lithium battery detection, and particularly discloses a lithium ion battery fault detection method, which comprises the following steps of: firstly, acquiring total current data of a battery pack in real time, and judging the current running state of a battery system according to the total current of the battery pack and the duration time; and when the battery system is in a standing state, calculating the voltage drop rate and the temperature rise rate of each single battery in a preset time window, and comparing the voltage drop rate and the temperature rise rate with corresponding thresholds to realize self-discharge detection and fault identification. And when the battery system is in a charging or discharging state, a deep learning algorithm is further introduced, temperature-pressure coupling time sequence fluctuation characteristics of each single battery are extracted, and temperature-pressure coupling time sequence fluctuation state consistency analysis is performed on each single battery, so that intelligent detection of faults of the single batteries in the charging and discharging process is realized. According to the method, the abnormal temperature and pressure fluctuation of the single battery in the charging and discharging process can be effectively captured, so that early warning and accurate positioning of a fault are realized.

The invention discloses a battery thermal runaway early warning method based on multi-sensing information fusion, which is suitable for safety management of a lithium ion battery. A fiber bragg grating sensor is embedded into a battery, temperature and strain multi-dimensional physical parameters of the battery are monitored in real time, external electrochemical parameters are combined, and a multi-source sensing information fusion system is constructed. And by analyzing a square curve of an internal strain derivative, temperature gradient change and voltage drop characteristics, a thermal runaway early-stage signal is extracted, and graded early warning is realized. According to the method, the hysteresis of traditional surface parameter monitoring is broken through, an early warning signal is provided before thermal runaway, and the safety and reliability of a battery system are remarkably improved.

The invention discloses a power quality rapid disturbance detection method based on improved K-S conversion. The method comprises the following steps: obtaining a discrete sampling sequence of power grid detection nodes; performing fast Fourier transform to obtain a signal frequency spectrum; iterative cyclic filtering processing is carried out on the signal frequency spectrum, and the maximum value of the filtered frequency spectrum is calculated to serve as a frequency feature point; carrying out improved K-S transformation on the signal to obtain a transformed matrix; extracting a fundamental frequency part from the transformed matrix to obtain a section of one-dimensional time signal representing a waveform of a fundamental wave in signal duration, calculating a maximum value, a minimum value and a sudden change time point to obtain time domain disturbance characteristics, and detecting disturbance amplitudes, starting time and ending time of voltage sag, voltage sag, voltage interruption and flicker; and determining the frequency, the amplitude and the duration of each frequency component according to the transformed matrix, and detecting frequency domain disturbance including harmonic waves and transient oscillation.

The invention relates to the technical field of industrial process control, and discloses an intelligent optimization control method of an alkaline water hydrogen production system, which comprises the following steps: a controller synchronously acquires real-time voltage, current and temperature data of an electrolytic bath; theoretical reversible voltage is calculated according to a Nernst equation, ohm voltage drop is eliminated, and a bubble additional impedance value representing the bubble coverage degree is analyzed; performing differential processing on the change rate of the bubble additional impedance value to generate a flow feed-forward control instruction, combining a feedback control instruction based on temperature deviation to synthesize a target rotating speed instruction, and driving an alkali liquor circulating pump to adjust the flow speed; according to the method, the bubble impedance observation model is constructed, so that zero-delay sensing and decoupling control over the state of bubbles in the electrolytic cell are achieved, hysteresis of single temperature feedback is eliminated, and the problems of actuator saturation and model aging drifting are solved.

The invention discloses a cooperative ride-through control method for a new energy flexible direct current transmission system under a receiving end fault, and relates to the technical field of flexible direct current transmission, and the method comprises the steps: periodically collecting the grid-connected point voltage of a receiving end converter station, an output active current reference value, and the real-time data of the online impedance estimation of a converter station side; calculating the minimum possible true values of the converter station side equivalent reactance and the short circuit point voltage; calculating a reactive current reference value and an active current reference value of the flexible DC receiving end converter station after the fault occurs; calculating the input time of the energy consumption resistor; the reactive current reference value, the active current reference value and the energy consumption resistor input moment are sent to a receiving end converter station; and when the receiving-end converter station detects that the voltage drop of the grid-connected point meets the low-voltage crossing starting condition, the receiving-end converter station enters a low-voltage crossing control mode and starts control, and the receiving-end converter station performs corresponding adjustment. By the adoption of the method, the rising speed of the direct-current voltage is reduced fundamentally, the input time or the input frequency of an energy consumption device is reduced, and the economical efficiency of fault ride-through is improved.

The present application provides a method and system for predicting the remaining service life of an IGBT device, comprising: simulating an IGBT device power cycle aging experiment, collecting conduction voltage drop historical data on the basis of the experiment, and respectively obtaining a model parameter empirical value and a model parameter estimated value on the basis of the conduction voltage drop historical data; constructing a first state weight on the basis of the current operation state, and performing smooth adjustment on the model parameter estimated value on the basis of the model parameter empirical value and the first state weight to obtain a parameter correction result; and establishing a state transition equation on the basis of the parameter correction result, and predicting the remaining service life of an IGBT device on the basis of the state transition equation. Use of the present application can improve the accuracy of prediction of the remaining service life of the IGBT device.

The invention discloses a main station big data-based low-voltage transformer area topology hierarchy identification method and system, and the method comprises the steps: constructing a multi-dimensional voltage feature vector through the voltage time sequence data, collected by a main station side, of a transformer area general meter and a user ammeter, and forming an electrical feature matrix through feature extraction; and on the basis, judging the station area affiliation and the phase line affiliation of the user electric meter through similarity calculation. Then, generating a stable consensus cluster based on multi-time window clustering and the copolymerization matrix, and mapping the cluster into a virtual electric meter box node; constructing a minimum spanning tree and carrying out directionalization to obtain an initial radial topological structure; further introducing an electrical consistency criterion based on correlation of voltage drop and subtree current, performing multi-candidate structure optimization on the preliminary topology, and finally obtaining an optimal transformer area topology hierarchical structure consistent with a physical rule; high-precision automatic identification of the low-voltage transformer area topology can be realized without manual participation, and effective support is provided for digital operation and maintenance of a power distribution network.

The invention relates to the technical field of network construction type converter control, in particular to a network construction type converter fault ride-through method and system based on dynamic virtual resistance control, and the method comprises the steps: adding a control link based on virtual impedance in a network construction type converter control system; detecting the actual value of the power grid voltage, and judging whether the power grid voltage drops or not; detecting the current amplitude output by the grid-forming converter in real time, and judging whether the current amplitude exceeds a set value or not; if one of the two conditions is met, a virtual impedance control link is started: stage-type current limiting control is performed on the virtual resistor, and the size of the virtual resistor provided by the network-forming converter to the power system is adjusted in real time along with the amplitude of the fault current; and when the power grid voltage recovers and the current amplitude is smaller than the set value, the virtual resistor staged current-limiting control exits. According to the invention, the amplitude limiting of the fault current in the fault ride-through of the network-constructed converter can be realized, so that the fault ride-through capability and transient stability of the network-constructed converter are improved.

The invention discloses a Schottky diode and a manufacturing method thereof, the Schottky diode comprises a substrate, an epitaxial layer, a cathode layer, a plurality of first ion implantation regions, a plurality of first grooves, a second barrier metal layer and an anode layer, the plurality of first ion implantation regions and the plurality of first grooves are arranged in a main junction region, a first ion implantation region is arranged at the bottom of the first groove, a PN junction is formed between the first ion implantation region and the epitaxial layer, a second ion implantation region is arranged at the bottom of the first groove, a PN junction is formed between the second ion implantation region and the epitaxial layer, and a first barrier metal layer is arranged on the side wall of the first groove; the second barrier metal layer is arranged on one side, far away from the substrate, of the epitaxial layer, is positioned in the main junction region and is connected with the first ion implantation region and the first barrier metal layer; the anode layer is disposed on the second barrier metal layer. Through the above design, the reverse leakage current of the Schottky diode can be greatly reduced, and the forward conduction voltage drop of the Schottky diode can be reduced.

The invention relates to a virtual synchronous machine transient stability optimization control system and method, and the method comprises the steps: sampling a three-phase power grid to detect the angular frequency of a power grid in real time, carrying out the subtraction of the angular frequency and the angular frequency outputted by an active-frequency control module of a virtual synchronous machine, multiplying a coefficient, and introducing into a reactive-voltage control module. The voltage sag dynamic state of the virtual synchronous machine under the power grid voltage drop is slowed down by means of angular frequency fluctuation caused by active power adjustment of the virtual synchronous machine under the power grid voltage drop, and the transient voltage supporting capacity of the virtual synchronous machine under the fault is improved. Under stable operation, the output angular frequency of the active power-frequency control module of the virtual synchronous machine is equal to the angular frequency of the power grid, so that the additional loop has no influence on the virtual synchronous machine during stable operation. According to the invention, the difference between the power grid angular frequency and the output angular frequency of the active-frequency control module is introduced into the reactive-voltage control module, so that the system can maintain good damping characteristics during the transient period, and the transient stability of the virtual synchronous machine system is improved.

The invention provides a fault ride-through control method for a network construction type converter, and belongs to the technical field of energy storage converters and the like. The method comprises the following steps: firstly, measuring PCC voltage and power grid side current, calculating amplitudes of the PCC voltage and the power grid side current, and then judging whether the PCC voltage drops below a set threshold value or not; if not, keeping the active power reference and the voltage amplitude reference unchanged; and if so, performing active power reference modification: judging whether a current limiting strategy is triggered, if not, locking the PCC voltage reference as a measured value, and if so, gradually decreasing the PCC voltage reference by an increment value based on the measured value. According to the invention, accurate evaluation of the existence of the stable equilibrium point is realized; meanwhile, an improved fault ride-through control method is provided, active power reference and voltage amplitude reference are dynamically modified, so that the grid-forming converter is transited to a new stable balance point during a fault period, and current limiting, transient synchronization stability improvement, PCC voltage source characteristic maintenance and maximum fault current output can be taken into account.

The invention discloses a photovoltaic inverter direct current component detection circuit, which relates to the technical field of photovoltaic detection, and comprises a photovoltaic inversion module used for photovoltaic conversion and inversion; the intelligent control module is used for signal receiving and module control; the detection control module is used for transmitting the input voltage and the output voltage of a switching element in the working of the upper half bridge or the lower half bridge of the photovoltaic inversion module; the first voltage drop module is used for calculating the voltage drop of an upper half-bridge switch element of the photovoltaic inversion module; the second voltage drop module is used for calculating the voltage drop of a lower half-bridge switch element of the photovoltaic inversion module; the voltage drop comparison module is used for voltage comparison; the output module is used for filtering and outputting electric energy; the component detection module is used for extracting the direct current signal and performing two-stage amplification; and the state judgment module is used for detecting positive and negative states of the direct current signal and carrying out voltage comparison. The photovoltaic inverter direct current component detection circuit can quickly and effectively detect the direct current component and automatically detect the generation reason of the direct current component.

The invention provides an EIS on-line detection system and method for a high-power fuel cell system, a main loop of the EIS on-line detection system adopts two Boost type converter topological structures which are connected in parallel, and small signal excitation injection is carried out through an auxiliary DC / DC converter 2; the control system comprises a sampling system, a PWM drive circuit, a communication module and an embedded controller. Establishing a battery equivalent circuit model; when a high-power fuel cell system runs, a multi-frequency sine periodic signal optimized by a non-dominated sorting genetic algorithm improved based on Tent chaotic mapping is injected into an output current of an auxiliary DC / DC converter 2; sampling the voltage of a single body or a galvanic pile, measuring current data, calculating the voltage drop corresponding to the internal resistance of the current data, converting a time domain signal into a frequency domain signal, and obtaining the battery impedance information in the corrected Foouquet equivalent circuit model; importing the characteristic parameter data into a least square support vector machine (LSSVM) for training and testing, and performing in-situ detection and fault diagnosis on line; according to the invention, a new way can be provided for active diagnosis and early warning of faults.