1444 results about "Overcurrent" patented technology

The invention discloses a primary and secondary fusion pole-mounted intelligent circuit breaker. The primary and secondary fusion pole-mounted intelligent circuit breaker comprises a fault detection module, a protection action module, a reclosing module and an information reporting module, the fault detection module collects multi-dimensional electrical quantity through a current transformer and a voltage transformer, and judges a fault and identifies the type in combination with a dynamic normal range and a duration threshold. The protection action module calculates the fault distance based on the correction impedance, judges whether to act or not by combining the current flow direction and the protection range, and selects a protection level according to the fault severity; the reclosing module dynamically sets an observation time window, distinguishes instantaneous or permanent faults through a retest verification mechanism, and adaptively adjusts a reclosing strategy; and the information reporting module uploads fault related information. According to the method, the problems of high misjudgment rate, poor protection selectivity, rigid reclosing logic and the like of a traditional circuit breaker are solved, and the accuracy, quickness and self-healing capability of power distribution network fault processing are remarkably improved.

The invention discloses an insulation detection method for an electric automobile, belongs to the technical field of high-voltage safety monitoring of the electric automobile, and solves the problem that the insulation detection precision is reduced due to electromagnetic interference, impedance fluctuation and capacitive effect coupling in a dynamic load switching process. According to the scheme, a test sequence of discrete frequency points is applied to a high-voltage system; measuring a response current value through a current sensor and calculating a ground distributed capacitance value; connecting a test voltage source between positive and negative electrodes of the high-voltage system through a coupling circuit; applying a first pulse signal during no-load, dynamically setting the width according to the capacitance value, measuring a first response current value, and calculating an initial insulation resistance value; a second pulse signal with the same parameter is applied in the load state window, a second response current value is measured, and differential filtering is carried out in combination with the initial value to eliminate load noise; and comparing the filtered insulation resistance value with a threshold value, and outputting a fault signal when the insulation resistance value is lower than the threshold value. The method is used for monitoring the insulation state of the high-voltage system in real time and accurately early warning faults.

The invention relates to the technical field of wiring terminals, in particular to an intelligent testing method and system for the contact resistance of a wiring terminal, and the method comprises the following steps: adjusting the resistance testing frequency according to the environment temperature to adapt to different conditions, combining current and voltage data, analyzing the historical change trend of the resistance, predicting the potential change range, and obtaining the contact resistance of the wiring terminal through the current and voltage data. Evaluating the mutual influence with the resistor, judging the abnormal reason of the resistor, adjusting a test scheme according to fault diagnosis, predicting potential faults, and making a test plan. According to the invention, through environment induction and data analysis, the resistance test frequency is adjusted in real time to adapt to environment change, so that the resistance measurement in the test process is more sensitive and accurate, the response speed and data quality of the test process are improved, historical and current resistance data are automatically analyzed, potential faults can be effectively predicted and identified, and the test efficiency is improved. Problems caused by operation errors are reduced, and a prospective fault prediction function enables the adjustment of the test period to be more scientific.

The invention discloses a driving control method of a DAB converter and related equipment, and relates to the technical field of power electronic converter control, and the method comprises the steps: calculating a voltage transformation ratio based on an input voltage and an output voltage through a current stress adjustment module, and calculating an output power based on the output voltage and an output current, substituting the voltage transformation ratio and the output power into a current stress adaptive minimization algorithm to solve an internal phase shift angle; meanwhile, through a PI controller, an external shift phase angle is adjusted based on a difference value between the instruction voltage and the output voltage; outputting the inner phase shift angle and the outer phase shift angle to a PWM modulation generator to generate a switching tube driving signal; the DAB converter is controlled by the driving signal to realize rated voltage output and current stress minimization, so that the efficiency and reliability of the converter are improved.

The invention discloses a CPLD-driven IGBT short-circuit current dynamic monitoring method and system, and relates to the technical field of power electronics, and the method comprises the specific steps of S100 real-time data acquisition, S200 dynamic threshold calculation, S300 short-circuit state judgment, S400 rapid protection execution, and S500 fault data recording and uploading. Accurate and prospective judgment of the short circuit state of the IGBT is achieved, two stress parameters including the direct-current bus voltage and the junction temperature serve as independent variables, when the bus voltage rises, the voltage stress borne by the IGBT in the turn-off period is increased, meanwhile, the current peak at the short circuit moment is more remarkable, early warning is conducted in advance by dynamically lowering the threshold value, and therefore the short circuit state of the IGBT is accurately judged. According to the mechanism, the monitoring system does not simply respond to the occurred overcurrent, but can pre-judge the safety boundary of the device under the current working condition, so that intervention is implemented before the current really reaches a dangerous peak value, and a protection blind area under a severe working condition is effectively avoided.

The invention provides a fault ride-through control method and a fault ride-through control system for a grid-forming converter, which are characterized in that the current of the grid-forming converter under an asymmetric fault is controlled by adopting a negative-sequence current reference generation strategy aiming at an inner ring of a controller, and negative-sequence reactive current is injected into a power grid; adopting a partial sequence current amplitude limiting strategy to control the maximum phase current amplitude of the injected asymmetric current not to exceed an amplitude limiting value; controlling the boundary of an active reference value by adopting an active reference value amplitude limiting strategy for an active synchronization ring; a synchronous damping link is adopted to enhance damping in power angle swing; for a reactive voltage loop, a reactive voltage variable coefficient control strategy is adopted to control the output of the maximum reactive current; and an internal potential locking strategy is adopted to suppress overvoltage. According to the invention, negative-sequence reactive power is provided, and overcurrent of each phase is avoided; the power angle characteristic is improved, and the transient stability is improved; stable transient voltage support is provided in a current output capability range; and after the fault is recovered, the voltage of the converter grid-connected point is smoothly recovered.

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.

The invention relates to the technical field of power system monitoring, and provides a power grid data fault diagnosis method and device based on an intelligent power monitoring instrument, and the method comprises the steps: collecting the operation data of a power grid through the intelligent power monitoring instrument, and generating a fault feature vector containing the multi-dimensional feature parameters of voltage, current and power factor; matching and comparing the feature vector with a preset fault criterion; determining a specific fault type based on a comparison result of the characteristic parameters and a threshold value, including identifying voltage abnormity through a voltage deviation rate, identifying harmonic exceeding through a current harmonic total distortion rate, and identifying a three-phase imbalance fault through a three-phase imbalance degree; for judgment of the three-phase unbalance degree, mean square error statistic calculation is adopted, and a safety coefficient is introduced for threshold comparison; and the fault influence priority is evaluated by quantifying the degree of deviation of each characteristic parameter from the threshold. The fault diagnosis efficiency and reliability can be improved, and intelligent decision support is provided for safe operation of a power grid.

The invention provides a device for inhibiting drain-source overvoltage and overcurrent through active gate drive of a silicon carbide MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), aiming at solving the problem of voltage or current overshoot caused by circuit parasitic parameters in a high-speed switching process of the SiC MOSFET and simultaneously considering the switching speed and energy loss balance. According to the device, drain-source voltage vdc and direct-current bus voltage of the SiC MOSFET are collected to serve as feedback signals, and gate driving voltage and equivalent gate resistance are dynamically adjusted; in a key stage (a Miller plateau switching-on period and a voltage rising period switching-off period) of a switch transient state, a gate resistance network is switched through a logic control circuit, and suppression of drain current overshoot and drain-source voltage overshoot is realized. Simulation verification shows that the device can reduce voltage overshoot by 20%-30% and current overshoot by 25%-60%, only a single voltage feedback channel is needed, the cost is obviously lower than that of a traditional multi-signal acquisition active gate driving scheme, and the device is suitable for a high-efficiency SiC MOSFET power converter.

The invention belongs to the field of overvoltage protection, and relates to an overvoltage stabilizing and protecting device which comprises a data acquisition operation module, a control logic module, a display module, an overvoltage protecting assembly and a high-voltage vacuum circuit breaker or an electric isolation handcart structure. The real-time monitoring and protection of the working state of the overvoltage protection assembly are realized; through the arrangement of the high-voltage circuit breaker or the electric isolation handcart, when the overvoltage protection assembly is detected to be abnormal, the connection between the overvoltage protection assembly and the high-voltage bus can be rapidly cut off, so that the system safety is ensured; the device integrates a transient fault recording function and can capture wave map data before and after a power frequency overvoltage fault of the system; the overvoltage protection assembly in the device adopts a geometric center air cooling heat dissipation mode, the fan is quick in starting response, the operating temperature of the overvoltage protection assembly is greatly reduced, the operating time of the overvoltage protection assembly can be effectively prolonged, and the device adopts an integrated modular structural design, so that the operation safety, the maintenance and the management are greatly facilitated.

The invention belongs to the technical field of electrical equipment fault monitoring, and discloses a fault monitoring system for electromechanical installation engineering, which comprises a high-impedance fault identification module, extracts nonlinear harmonic features through current signals, constructs a frequency domain-time domain joint feature set in combination with space-time magnetic distortion in an electromechanical installation process, and performs fault identification on the nonlinear harmonic features through the high-impedance fault identification module. Non-linear characteristic response identification of the high-impedance fault is carried out, and a high-impedance fault characterization result is output; the transient fault capturing module is used for positioning a risk time window according to a high-impedance fault characterization result, and identifying the starting and ending boundaries of an electrical disturbance behavior in combination with a double-threshold mutation mechanism; synchronously extracting corresponding operation condition parameters, constructing a short-time process behavior model taking electrical disturbance as a source, and outputting a transient disturbance sequence; and the sensitivity of fault identification, the accuracy of positioning and the real-time performance of diagnosis are integrally improved.

The invention discloses a feedback field weakening control method and system for a surface-mounted permanent magnet synchronous motor, and the method comprises the steps: collecting a rotation speed feedback value of a motor, and controlling the operation of the motor through employing a maximum torque current ratio if the rotation speed feedback value is smaller than a rated rotation speed; calculating a first flux-weakening rotating speed according to the real-time load rate and the bus voltage fluctuation, and if a rotating speed feedback value of the motor is greater than the first flux-weakening rotating speed, entering a first flux-weakening mode: calculating a difference value between an output voltage amplitude and the bus voltage, generating a d-axis current compensation value, and performing load compensation and rotating speed compensation on the d-axis current compensation value to obtain a d-axis current given value; the maximum value of the q-axis current is calculated, given voltage values of the d-axis and the q-axis are generated, and the motor is driven to operate; and calculating a second flux-weakening rotating speed according to the q-axis current maximum value and the voltage margin, and if the rotating speed feedback value of the motor is greater than the second flux-weakening rotating speed, entering a second flux-weakening mode: further limiting the q-axis current maximum value through a current limit circle and a voltage limit circle on the basis of the first flux-weakening mode.

The invention relates to the technical field of fault detection, in particular to a high-voltage connector loosening fault detection method and device and an automobile, and the method comprises the following steps: forming a surface acoustic wave resonator array based on an interdigital transducer array, an acoustic wave resonator and a flexible waveguide; butting a signal source radio frequency cable with the pin interdigital electrode chip, triggering data acquisition, performing Fourier transform on original data, and judging the loosening risk of the connector according to each parameter threshold value; carrying out three-dimensional modeling on the connector plugging interface, carrying out modal analysis on the model, and obtaining surface acoustic wave frequencies, group velocities and phase distribution under different pre-tightening forces so as to identify a contact force abnormal region; based on a multi-stage early warning mechanism, rapid locking is achieved through electrorheological fluid, and displacement is finely adjusted through a magnetostrictive rod. According to the invention, the loosening hidden danger can be quickly and accurately locked, a tight protection system is constructed by multi-stage early warning and mechanical self-locking, and the loosening risk of the high-voltage connector can be greatly reduced from early warning to active intervention.

According to the pure hardware PID current control system and method based on the direct current brushless motor provided by the invention, the negative voltage interference generated by electromagnetic induction is directly filtered in the bus current signal acquisition stage through the cooperation of the current sampling module and the bus negative voltage elimination module; the problem of signal distortion caused by negative voltage in a traditional sampling circuit is eliminated, and the current effective value detection precision is improved; the PID control module constructed based on pure hardware calculates a difference value between a target voltage and an actual voltage in real time through an analog circuit, and generates a proportional, integral and differential composite compensation signal, so that a PWM modulation circuit can adjust duty ratio output in real time according to the compensation signal, and it is ensured that a bus current of a motor driver is rapidly converged to a target value; the whole scheme does not need to depend on a microcontroller and a complex software algorithm, closed-loop current control is achieved through discrete devices, and the system cost is reduced.

The invention discloses a line diagnosis method and circuit, and the method and circuit are used for a data communication system, and the method comprises the steps: detecting a first current on a high-side switching tube and / or a second current on a low-side switching tube; judging the states of the high-side switch tube and the low-side switch tube based on the detection result; and judging whether open circuit and short circuit exist at the line positive end and the line negative end and whether short circuit exists between the line positive end and the line negative end and the power supply voltage and the ground voltage based on the states of the high-side switch tube and the low-side switch tube. According to the line diagnosis method and the diagnosis circuit, the accuracy of fault diagnosis in the bus power supply and power-on process can be improved, false report and missing report of faults are reduced, and chip and line burnout caused by long-time overcurrent is avoided; by means of fault detection of the communication state, the line fault diagnosis precision in bus power supply communication is improved, false alarms and missing alarms are reduced, and overcurrent is avoided.

The utility model relates to the field of electric power facilities, in particular to a stable and reliable drop-out fuse, which comprises an insulator, an upper terminal, a lower terminal, a fuse tube, an upper static contact and a lower static contact. A fuse is arranged in the fuse tube, an upper moving contact is arranged at the upper end of the fuse tube, a lower moving contact is arranged at the lower end of the fuse tube, and the lower moving contact is movably connected to the lower static contact through a trunnion; the lower moving contact is also provided with an elastic wire pressing plate which assists in tensioning the fuse wire. The lower moving contact is provided with a first line pressing terminal, the lower static contact is provided with a second line pressing terminal, and the lower end of the fuse is led out from the fuse tube, penetrates through the first line pressing terminal and then is connected with the second line pressing terminal. And an insulating sheath is arranged at a position where the fuse wire is connected with the elastic wire pressing plate. The sheath is additionally arranged at the contact position of the tail end of the fuse wire and the fuse wire pressing plate to form insulation isolation, so that current does not pass through two sides of the trunnion by the fuse wire, and the heating defect caused by poor contact between the trunnion and the lower static contact is avoided.

The invention relates to a charging control method, device and equipment and a storage medium, and relates to the technical field of automobiles. The method comprises the steps that a charging control device determines a down-regulation parameter of a charging demand current of a battery of the vehicle under the condition that an input current is larger than or equal to an overcurrent fault threshold value and the duration is larger than a first preset duration, and the input current is a current flowing into the battery. Further, the charging control device adjusts the charging demand current of the battery based on the down-regulation parameter to obtain a first charging demand current, and the first charging demand current is smaller than the charging demand current before adjustment; and sending the first charging demand current to an electric pile for charging the vehicle, so that the electric pile adjusts the output current of the electric pile according to the first charging demand current until the input current is smaller than the overcurrent fault threshold value. Therefore, charging control on the battery of the vehicle is realized, and the safety risk of overcurrent is reduced.

The invention discloses a rapid pilot protection method for a flexible DC line, and the method comprises the steps: firstly collecting the positive and negative current data of the DC line in real time, calculating the current change rate, and starting protection if the current change rate exceeds a preset threshold value; locking a fault moment data window, and calculating an H distance of a positive and negative electrode current sequence based on a Hausdorff distance so as to distinguish an inter-electrode fault or a single-electrode fault; thirdly, calculating a fault current break variable sequence by using the current data in the data window to obtain a current included angle of the side; then, current included angle information of the two sides is interacted with an opposite-side protection device; calculating a product average value, namely a fault current included angle entropy, according to the current included angles on the two sides; and finally, by judging whether the included angle entropy is greater than an internal and external fault threshold value or not, accurately identifying an internal fault and triggering tripping, or judging the internal fault as an external fault. According to the method, millisecond-level rapid protection is realized through the current included angle characteristic quantity and the included angle entropy criterion, and the method has high transition resistance resistance and low communication synchronization requirements.

A protection method for a voltage flexible control circuit applied to a photovoltaic power station comprises the steps that a multi-layer electrical signal fusion criterion system comprising an abnormal working condition triggering layer, a fault area recognition layer and a fault type judgment layer is constructed, firstly, overcurrent and overvoltage signals are collected through the abnormal working condition triggering layer, and protection logic starting is triggered; the fault area identification layer is used for distinguishing whether the fault exists inside or outside the AC-DC-AC converter; and finally, the fault type judgment layer is used for accurately identifying the faults of the AC-DC-AC converter, the series coupling transformer, the line and the far-end line. By introducing differential protection action chains and hierarchical response mechanisms corresponding to different fault types, accurate isolation of a fault area is realized, and meanwhile, the problems of system mistaken switching and excessive protection caused by extensive protection actions are effectively prevented.

The invention discloses an energy storage type SOP black-start method, system and device based on improved VSG network construction control and a medium, and relates to the field of power grid black-start, and the method comprises the steps: an energy storage type converter MMC carries out the active and reactive control based on an improved VSG network construction control strategy; a non-fault side MMC is controlled to firstly close an isolation circuit breaker and slowly charge a direct-current capacitor, and when the voltage reaches a set threshold value, a current-limiting resistor is quitted; the fault side MMC is started by the same step as the non-fault side MMC; after synchronization is completed, AC circuit breakers between the non-fault side MMC and the feeder load and between the fault side MMC and the feeder load are closed respectively; based on the collected power grid power data, MMC output parameters are adjusted to meet the power grid connection condition, the control mode is switched according to the grid connection state, and the black start process is ended. And by arranging the black start resistor for current-limiting charging and sub-module voltage balance control, the phenomena of overcurrent and voltage unbalance in the black start process are avoided.

The invention discloses a network construction type VSG power grid fault active support cooperative control method, and belongs to the technical field of new energy grid-connected control. According to the method, the power grid voltage is monitored in real time, and a cooperative strategy is dynamically triggered: when the voltage drops below a set value, a cooperative control mechanism is started, including (1) self-adaptive active power adjustment based on a power angle stability margin and dynamic correction of a power instruction value to suppress kinetic energy accumulation of a rotor; (2) voltage tracking type reactive compensation is superposed in a reactive control loop, reactive current is increased in real time according to the drop depth, continuous reactive support is provided, and steady-state overcurrent is restrained; and (3) inputting a virtual resistance inductor, and limiting a transient over-current peak value by suppressing a dq-axis coupling current component. When the voltage is normal, the conventional VSG control mode is maintained. According to the invention, power-reactive power-impedance three-dimensional cooperation is realized, power angle stability, current limitation and voltage support are considered, and the stability and active support capability of the network-forming VSG under the power grid drop fault are significantly improved.

The invention relates to the technical field of overcurrent protection, in particular to an active protection control method and system for power distribution switch control equipment, and the method comprises the following steps: a current sensing device obtains a current value sequence, a sliding window generates a current slope, impedance detection obtains an impedance sequence, and an impedance rate is obtained through least square; a correction coefficient is obtained through a difference value between an impedance rate and a reference value; a disturbance rate is calculated through a current extreme value; an input classifier outputs a control instruction; a threshold and instruction logic and operation are carried out; according to the method, the coupling relation between the current slope and the impedance rate is dynamically analyzed, a multi-dimensional parameter system is constructed, a dynamic adjustment threshold value of a composite judgment basis is established, disturbance and overload are distinguished, the reliability is enhanced by combining a classifier recognition mode and logic and operation, feedback closed-loop control is introduced, the non-linear load adaptability is improved, and the maloperation rate is reduced; the sensitivity is enhanced, and the safety margin is optimized.

The invention provides a zero-voltage ride-through control method for a self-synchronizing voltage source doubly-fed wind turbine generator, which comprises the following steps that: when the self-synchronizing voltage source doubly-fed wind turbine generator is in a transient state, a grid-side converter adopts vector control, and a rotor-side converter adopts additional virtual impedance and annular current limiting; the transient overcurrent of the grid-side converter and the rotor-side converter can be effectively suppressed, so that the continuous operation capability of the wind turbine generator in the zero-voltage ride-through period can be maintained; meanwhile, by improving the transient capacity and the transient reactive current amplitude of the converter, the transient voltage supporting capacity of the wind turbine generator during the zero voltage ride-through period can be effectively provided; when the self-synchronizing voltage source doubly-fed wind turbine generator set is in a transient state, overvoltage of direct-current bus voltage is limited by a Chopper circuit, active-priority current amplitude limiting control is adopted by a grid-side converter, parameters of a current inner ring PI controller of a rotor-side converter are optimized, energy balance of a direct-current side can be achieved in the zero-voltage ride-through period, and stability of the direct-current bus voltage is maintained.

The invention discloses a time sequence fault current-limiting control method and system compatible with a grid-connected guide rule for a network construction type doubly-fed wind turbine generator, and the method comprises the following steps: freezing external power control when a low-voltage ride-through event of a power grid is detected at the initial stage of a fault, and suppressing transient overcurrent through dynamically adjusting the resistance component of virtual impedance; in the fault stable stage, an electromotive force compensation increment is calculated on the basis of grid-connected guide rule requirements at the moment 4 tau after the fault occurs; in the fault clearing stage, after it is detected that the fault is cleared, electromotive force compensation is stopped; gradually recovering the virtual impedance to a rated value through the dynamic coefficient A; in the fault recovery stage, active control and reactive control are recovered in sequence, power output is recovered to the level before the fault within one second, and meanwhile the virtual impedance amplitude is gradually recovered to the rated value along with the voltage phase difference; the voltage phase jump amplitude and the voltage drop amplitude determined by the method have high robustness.

The invention discloses a fault networking operation control method and system under SVI power grid voltage phase jump. The control method comprises the steps of frozen active integral output, equivalent internal potential phase compensation and transient over-current suppression. And if the difference value between the power grid voltage angular frequency and the self-generated angular frequency is greater than a threshold triggering mark position 1, restoring to 0 after keeping for a set time. When the mark position is 1, 1) the active integral output is frozen, so that the self-generated angular frequency keeps the angular frequency unchanged at the moment before the fault; and 2) equivalent internal potential phase angle compensation: calculating a difference value between a power grid phase angle and a self-generated phase angle in real time, generating a compensation phase angle, and further generating an equivalent internal potential phase angle. During the fault ride-through period, transient overcurrent is suppressed, according to the overcurrent multiple, the original virtual impedance set multiple is increased, and / or additional virtual impedance is input and multiplied by inductive current to obtain compensation voltage, and virtual impedance and current inner loop control is carried out after the compensation voltage and the grid-connected voltage are subtracted from the remolded internal potential instantaneous value at the same time.

The invention provides an intelligent lightning arrester for a line. The intelligent lightning arrester comprises a lightning arrester body and an intelligent control box, the lightning arrester body is used for providing a low-impedance grounding channel for overcurrent when overvoltage caused by lightning or switching operation occurs on a line, so that the overvoltage is limited below a safety level, subsequent electrical equipment is protected from being damaged, the lightning arrester body recovers to an insulation state after the overvoltage disappears, and normal operation of a power system is guaranteed. The intelligent control box comprises an embedded intelligent sensing module and a diagnosis module, and the embedded intelligent sensing module is used for collecting operation state parameters of the lightning arrester body in real time; and the diagnosis module is used for evaluating the insulation state of the lightning arrester body by adopting a partial discharge mode recognition model according to the operation state parameters of the lightning arrester body, and predicting the aging trend of a valve plate unit of the lightning arrester body by adopting a valve plate aging trend prediction model. The lightning arrester disclosed by the invention has the dual advantages of compact structure and high-performance protection.

The invention discloses a self-adaptive current-limiting control method and related device for a network construction type energy storage converter under a symmetric fault of a power grid, and belongs to the technical field of network construction type energy storage converter control, and the method comprises the steps: constructing a corresponding fault current dynamic response model based on the network construction type energy storage converter under the symmetric fault of the power grid; generating a self-adaptive current-limiting control strategy based on the voltage drop depth of the power grid; wherein the self-adaptive current-limiting control strategy comprises the steps of carrying out overcurrent steady-state component suppression based on a phasor current-limiting method and carrying out overcurrent transient-state component suppression based on a virtual impedance control method, and self-adaptively adjusting a power instruction to meet a system support requirement in a current-limiting process; a fault current dynamic response model is solved through a self-adaptive current-limiting control strategy, a current-limiting control scheme is obtained, it can be ensured that the converter maintains the networking characteristic in the fault period, steady-state and transient overcurrent is effectively restrained, output current is strictly limited within a safety threshold value, and transient stability of a system is maintained.

The invention discloses a self-adaptive virtual inertia control system and method for a UPQC, and relates to the technical field of power distribution networks. A frequency voltage droop unit is used for applying active droop frequency control and reactive droop voltage control to a self-adaptive virtual synchronous machine; the self-adaptive virtual inertia calculation unit is used for determining a small disturbance quantity corresponding to actual active power, a small disturbance quantity corresponding to actual reactive power and a small disturbance quantity corresponding to actual frequency which are output by the self-adaptive virtual synchronous machine based on a virtual synchronous machine algorithm, active droop frequency control and reactive droop voltage control; and based on the small disturbance quantity corresponding to the actual active power, the small disturbance quantity corresponding to the actual reactive power and the small disturbance quantity corresponding to the actual frequency, a self-adaptive adjustment model of the virtual inertia is determined. The problems of power fluctuation and overcurrent in the transient process of traditional VSG control are effectively solved, better dynamic response is achieved, and the stability of the frequency and voltage of the independent microgrid is improved.

The invention discloses an adaptive virtual impedance-based fault current limiting method for a network-forming converter, and belongs to the technical field of converter control. Comprising the following steps: collecting grid-side voltage, converter-side voltage and converter output current; carrying out current amplitude calculation on the grid-side voltage quantity to obtain a current effective value of the port of the converter; judging whether the current effective value of the current transformer port exceeds a current threshold value of the current transformer; and if yes, self-adaptive virtual impedance is introduced to carry out converter fault current limitation. The resistance part of the virtual impedance is used for suppressing surge current at the beginning of a fault; and the reactance part is used for suppressing the effective value of the fault transient current within the current limiting range. In the fault process, the current virtual impedance value is adaptively changed according to the effective value of the current overcurrent, and the virtual impedance can be automatically quitted after the fault end stage. The method is suitable for fault current suppression of the network-forming converter in various control modes, and has good feasibility and practical value.

Disclosed are methods and systems for suppressing extreme voltage surges due to transient electromagnetic energy disturbance such as a detonation of a nuclear weapon at high altitude generating an EMP (HEMP) comprising E1, E2, and E3 component pulses. Surge protection assemblies form a surge protection device (SPD) mounted directly on AC and DC power line conductors with embedded overcurrent protection. The inline mounted SPD eliminates connecting wire leads, propagation time delay response, and voltage drops due to wire inductance, providing accurate clamping level responses. The protecting assemblies are selected and coordinated to achieve a predefined response to react at protection threshold voltage levels and with current capacity to mitigate complex components of HEMP. The tertiary protection assembly disconnects an electrical load after a prolonged overvoltage is present associated with a Geomagnetic disturbance and reconnects the electrical load when an overvoltage condition is not present.