5643 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 discloses a multi-source reactive power compensation control method, system, program, medium and device, and relates to the technical field of power grid systems, and the method comprises the following steps: extracting the dominant influence characteristics of the reactive power of a power grid as the input of a CNN-LSTM network, predicting the vacancy interval of the reactive power of the power grid, and taking the vacancy interval as the power distribution target of the multi-source reactive power compensation device; a power distribution model of the multi-source heterogeneous reactive compensation integrated system is constructed by taking minimization of system network loss and voltage drop and stability of the multi-source heterogeneous reactive compensation integrated system as optimization targets. The influence factors of the reactive power of the power grid are researched, and the influence characteristics are used as neural network input to predict the vacancy interval of the reactive power of the power grid, so that the spatial-temporal distribution characteristics of the reactive power of the power grid can be reflected, the change trend of reactive requirements is provided for power grid operators, and corresponding reactive compensation measures are taken in time.

The invention discloses a current detection system based on an inductance element, and relates to the technical field of current detection, and the system comprises a power switch module which is used for adjusting the conduction angle of a power switch device; the driving control module is used for improving the signal driving capability and lowering the driving potential; the current sampling module is used for detecting an inductive current change rate; the output detection module is used for adjusting a first fault threshold value and a second fault threshold value according to the aging degree and carrying out first-class short circuit or second-class short circuit detection; the conduction detection module is used for detecting saturated conduction voltage drop; the aging judgment module is used for detecting the aging degree; the detection adjusting module is used for adjusting a third fault threshold value according to the aging degree and cooperating with the short-circuit judgment module to perform second-class short-circuit detection; and the intelligent control module is used for signal receiving and module control. According to the current detection system based on the inductance element, the sensitivity of fault current detection is improved, whether the power switch module is normal or not is accurately judged, and the system safety is improved.

The invention relates to the technical field of power system automation, and provides a photovoltaic inverter low-voltage ride-through test result automatic analysis method, which comprises the following steps: reading low-voltage ride-through test data of a photovoltaic inverter, firstly judging whether no-load test data is qualified, and further judging whether load test data is offline; if the load test data is not offline, classifying the test data into a three-phase fault, a two-phase fault and a single-phase fault according to fault types, further calculating the voltage drop depth, the drop duration, the reactive current response time, the reactive current duration, the reactive current exit time and the active power recovery rate, and if the calculation result meets the standard requirement, determining that the test data is offline. And if not, automatically storing the test waveform and the calculation result in word, and otherwise, outputting that the test waveform and the calculation result are unqualified. The method and the system do not depend on manual identification, automatically and quickly calculate the low-voltage ride-through test result of the photovoltaic inverter in batches, automatically store the test waveform and the calculation result in the word document, and are simple to implement and high in accuracy.

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 utility model provides a bootstrap voltage charging circuit applied to a switching converter. The bootstrap voltage charging circuit comprises a bootstrap capacitor, a first switching tube, a first time delay circuit, a second time delay circuit and a logic judgment unit. The second end of the bootstrap capacitor is coupled with the switch node; the first end of the first switch tube receives a charging voltage signal, the second end of the first switch tube is coupled with the first end of the bootstrap capacitor, and the control end of the first switch tube receives a charging control signal; the first end of the bootstrap capacitor generates a bootstrap voltage signal; the first time delay circuit receives the switch control signal and outputs a first time delay signal; the second time delay circuit receives the switch control signal and outputs a second time delay signal; the logic judgment unit generates a charging control signal according to the first delay signal, the switch control signal and the second delay signal. According to the utility model, the diode is replaced by the switch tube with smaller conduction voltage drop, and by controlling the switch tube, the same effect as that of the diode can be achieved, and the problem of insufficient voltage can be avoided.

The invention relates to the technical field of data processing, in particular to a metal alloy current detection resistor detection data processing method and system. The method comprises the following steps: acquiring a plurality of current data and voltage drop data, and obtaining each sub-window of each current data; obtaining the stability degree of each sub-window of each piece of current data, and obtaining the authenticity of each sub-window of each piece of current data according to the stability degree of each sub-window of each piece of current data and the relation between the numerical value change of the current data and the numerical value change of the voltage data; acquiring a reference window of each current data according to the authenticity; according to the method, the fuzzy entropy value of each current data is obtained according to the reference window of each current data, each abnormal data is obtained according to the fuzzy entropy value of each current data, the judgment of the abnormal condition of the metal alloy current detection resistor is completed, the noise influence is avoided, and the accuracy of abnormal detection is improved.

The invention relates to the technical field of power supply of a direct-current light-superposed system, and discloses an operation mode switching control method applied to the direct-current light-superposed system, which comprises the following steps of: recording an output voltage when a combiner box has no current output before the direct-current light-superposed system is started; and executing different processes according to the duration after the direct-current stacked light system is started. According to the method, the impedance of the two sections of lines of the stacked light system is estimated through the operation information of the parallel stacked light system, updating is carried out according to needs, estimation of the voltage drop of the lines is achieved, and therefore the voltage of a base station power supply system is monitored by the stacked light system. The overload protection function of the parallel stacked light system is realized, the utilization rate of photovoltaic power generation is improved, the problems of overcharge and other abnormalities of a base station power supply system are solved, and the reliability of the stacked light system is improved.

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 present application relates to a flyback switch converter and a control circuit thereof; the control circuit comprises: a control signal generation module for providing a first control signal; a driver, for supplying a first switch transistor with a first driving signal according to the first control signal, so as to control the turning-on and off of the first switch transistor; the driver is further for performing overcurrent detection according to the voltage drop across the first switch transistor when the flyback switch converter performs the power output, and supplying a resonant capacitor with a discharge path when the flyback switch converter is shut down or enters the protection state. The present application can discharge residual charges on the resonant capacitor when the system is shut down or enters the protection state, and the system is less complex and with lower cost.

The invention discloses an abnormal battery cell identification method, computer equipment and a computer readable storage medium, and belongs to the technical field of power batteries, the identification method comprises the following steps: obtaining voltage data of a plurality of battery cells, and calculating a voltage drop of each battery cell under a standing condition based on the voltage data; for each battery cell, polymerizing the voltage drops under the plurality of standing working conditions in a first preset time period to obtain a polymerization result; and identifying an abnormal battery cell from the plurality of battery cells based on the aggregation result of each battery cell. The abnormal battery cell data is identified by using the outlier degree of the voltage drop of the battery cells in the battery pack under the standing working condition, the data validity is good, the identification result accuracy is high, and the use safety of the battery pack is ensured.

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.

An injection-locked oscillator includes a plurality of delay elements, two or more voltage control circuits, a phase comparator and a controller. The plurality of delay elements is connected in a loop and coupled to a global power supply. Each delay element has an input driven by a preceding stage and an output that drives a next stage. Each voltage control circuit couples one of the plurality of delay elements to the global power supply. The phase comparator is coupled to in-phase and quadrature outputs of the injection-locked oscillator. The controller is coupled to an output of the phase comparator and is configured to drive control inputs of the two or more voltage control circuits. The control input of each voltage control circuit determines a level of a voltage drop across the each voltage control circuit.

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.

A system includes a processing device and a measurement circuit coupled to the processing device. The system further includes an auxiliary voltage supply. The processing device and the measurement circuit are powered by the auxiliary voltage supply. The measurement circuit is to apply a test voltage to a first resistor and measure a voltage drop over the first resistor. The processing device is to determine, based on at least the voltage drop, an isolation resistance value between a chassis ground node and at least one of a battery pack or a battery link of a power system.

Limiting generator loads in a wind turbine having a power converter with a line side inverter configured as a grid forming inverter. A maximum grid current value is determined based on a measured generator load and a limit function. A virtual impedance value and a virtual voltage drop over the virtual impedance value are determined. A virtual synchronous machine angle is determined based on a power reference and the virtual grid power. The voltage reference for controlling the line side inverter is determined based on the virtual synchronous machine angle, the virtual voltage drop and the voltage magnitude reference.