435 results about "Voltage sag" patented technology

The invention discloses a low-voltage ride-through control method of a flywheel energy storage system, which is based on a low-voltage ride-through control strategy of model predictive current control (MPCC) so as to improve the low-voltage ride-through capability of the flywheel energy storage system when a power grid fails. A future current value is predicted through system modeling and a prediction algorithm, so that effective control is realized. The MPCC-based machine side-power grid side coordination control strategy can quickly respond to the voltage sag of the power grid, provide reactive power support, stabilize the voltage of the direct current bus, and ensure the safe and reliable operation of the flywheel energy storage system during the voltage sag period of the power grid. A traditional pulse width modulation (PWM) technology is abandoned, the optimal switching state is directly selected through a limited control set, and hardware implementation of a power grid side converter is simplified. A differential control strategy aiming at a power grid symmetric fault (three-phase voltage sudden drop) and an asymmetric fault (single-phase grounding) is provided, the method is suitable for a complex power grid fault scene, and the system universality is improved.

The invention relates to the technical field of power grid monitoring, and discloses a voltage sensor multi-parameter real-time monitoring method and device in an Internet of Things environment. According to the method, real-time voltage fluctuation data of a target area is acquired by deploying a multi-channel voltage sensor array and is transmitted to an edge computing node; dynamic feature extraction is executed in the edge nodes, and a multi-dimensional feature matrix containing voltage fluctuation ratio, harmonic distortion and phase deviation features is generated; identifying voltage sag, overvoltage and harmonic resonance event characteristics based on an anomaly detection model; spatial correlation modeling is carried out in combination with power grid topological structure parameters, the coupling strength of adjacent sensor node parameters is calculated, and a multi-parameter correlation map containing event propagation paths and influence ranges is generated; inputting the voltage into a diagnosis model to generate a power grid state diagnosis report, and dynamically adjusting the sampling frequency and filtering parameters of the voltage sensor according to the power grid state diagnosis report. According to the method, real-time monitoring and analysis of multiple parameters of the power grid can be realized, and comprehensive support is provided for power grid state evaluation.

The invention discloses an electricity utilization information acquisition intelligent configuration method based on a pattern recognition algorithm, and relates to the technical field of intelligent power grids, and the method comprises the steps: collecting a directional data stream, inputting a federal map neural network to construct a power distribution network physical connection relation, and generating a spatio-temporal topological feature vector; extracting a current effective value component of the directional data flow as an electrical load sequence, extracting an equipment state code to identify a voltage sag event, injecting voltage sag event associated disturbance into the electrical load sequence in combination with an event propagation path weight of a spatio-temporal topological feature vector, and generating an anti-fact sample set; and compressing the new configuration strategy through a knowledge distillation engine, and outputting an event response logic and a parameter adjustment instruction to form an executable configuration strategy. According to the method, through anti-fact sample generation and reinforcement learning optimization under spatial-temporal topological feature vector constraint, a physical rule deep embedding decision is realized.

The invention relates to a reconfigurable battery energy storage system grid-connected and off-grid seamless switching control method and device. The method comprises the following steps of: sensing a real-time power grid state, pre-judging a system operation mode, and acquiring a millisecond-level panoramic information flow of the power grid state through a high-speed sampling voltage sensor, a high-speed sampling frequency sensor, a high-speed sampling phase sensor and a high-speed sampling communication interface. And pre-judging the stability and disturbance trend of the power grid through a deep learning algorithm, executing a power distribution and voltage support algorithm in grid-connected and off-grid modes, and calculating an optimal switching opportunity point and a system reconstruction target topology scheme. Meanwhile, the harmonic distortion rate and the voltage sag depth are calculated in real time through discrete Fourier transform, so that a mode pre-judgment mechanism is automatically triggered. After switching, key parameters such as voltage, frequency and power are automatically corrected through real-time sampling and observation, and zero-sensing switching is achieved. The method can effectively improve the response speed and stability of the battery energy storage system when the power grid fails, and guarantees the safe operation of the power grid.

The invention relates to the technical field of electric energy identification, in particular to an energy consumption identification system based on a power transformation aliasing scene, which comprises a disturbance boundary extraction module, a boundary stability judgment module, an aliasing state identification module, a periodic power calculation module and an energy consumption attribution judgment module. According to the method, a voltage sag record with a phase offset characteristic is formed through continuous tracking of the periodic voltage fluctuation starting and ending point indexes, a stable fluctuation judgment mechanism is constructed in combination with offset statistics, and accurate identification of aliasing sections is realized by means of disturbance amplitude and frequency extraction. A power sequence is constructed on the basis of voltage and current synchronous sampling values, period integration is completed, a high-precision calculation result of energy consumption is formed, fine division of cross interference period energy consumption under the condition of no physical isolation is achieved, dependence of external metering equipment is avoided, independent quantization of overlapping load energy consumption is achieved, and the calculation efficiency is improved. And a feasible means is provided for energy efficiency evaluation in a non-intrusive load identification and high-coupling scene.

The invention discloses a reactive voltage bimodal control method and system suitable for a new energy power station, and belongs to the technical field of power system voltage control. The invention provides a dual-stage control optimization mechanism based on cooperation of a distributed phase modifier and a static var compensator in order to solve the problems of difficult steady-state voltage regulation and transient voltage instability of a new energy power station caused by wind-light output fluctuation and system short-circuit capacity reduction. According to the method, in steady-state operation, minimization of grid-connected point voltage deviation and maximization of dynamic reserve capacity of a phase modifier are taken as targets, reactive power output of two types of equipment is optimally distributed, and a proper amount of dynamic margin is reserved to support transient requirements; when it is detected that the voltage sag exceeds a safety threshold value, a transient response mode is immediately switched to, that is, phase modifier strong excitation control is activated, and reactive power output, reduced due to low-voltage limitation, of the static reactive power compensator is compensated; and when the voltage enters a recovery stage, triggering the phase modifier to reduce the output in advance through a pre-action instruction, and delaying to recover the steady state mode after the switching of the static var compensator is completed. A double safety protection mechanism is embedded in the whole control process, whether the grid-connected point voltage is in a safety interval or not is verified in real time, and the minimum operation interval of the switching equipment is forced to be executed. Simulation results show that the method can remarkably improve the voltage operation index of the new energy power station, the steady-state voltage fluctuation amplitude is greatly reduced, the transient fault recovery time is obviously shortened, the overvoltage peak value is effectively restrained to be within a safe range, and the industrial problem that the steady-state adjustment precision and the transient supporting capacity cannot be both considered by single reactive power equipment is solved.

The invention relates to the technical field of power systems, in particular to a power distribution network voltage sag compensation method, system and device and a medium. The method comprises the following steps: monitoring the voltage level of a power distribution network in real time by using a high-precision voltage sensor to obtain voltage data; identifying a voltage sag event based on the acquired voltage data; performing feature extraction on the determined voltage sag event; according to the extracted characteristic quantity, a compensation strategy is dynamically formulated, and the compensation strategy comprises the step of determining the amplitude and duration of compensation; executing voltage compensation through the grid-connected inverter according to the determined compensation strategy, wherein the output of the grid-connected inverter is adjusted according to the impedance change of the power grid and the influence of voltage disturbance; and monitoring the compensated power grid voltage, evaluating a compensation effect, and feeding back an evaluation result to optimize a subsequent compensation strategy. According to the invention, the voltage sag event can be rapidly and accurately detected, and an effective compensation strategy is formulated for compensation.

The invention discloses a multi-stage collaborative protection simulation verification method for a subway power supply system, and the method comprises the steps: building an integrated simulation model which comprises an automatic reclosing switch, a spare power automatic switching switch and an automatic change-over switch based on an MATLAB / Simulink platform, and especially carrying out the precise modeling of an advanced compensation function of ATSE. The model is verified by a power-off test, a simulation result and actually measured data are highly consistent in voltage recovery time, an error of advanced compensation action time of ATSE is less than 2ms, and dynamic characteristics of an actual system are accurately reproduced. Model simulation shows that the advanced compensation strategy of the ATSE can effectively control the voltage sag amplitude within 15%, the power supply reliability of the system is remarkably improved, and through strict'simulation-actual measurement 'double-track verification, the model accurately reproduces the dynamic characteristics of the actual system, and shows remarkable advantages in the aspect of improving the power supply reliability.

The invention relates to a voltage sag source positioning method based on measured data. The method comprises the following steps: S1, acquiring monitoring data; s2, performing sag-fault matching based on time sequence matching; the voltage sag of one monitoring point is matched with the same bus fault and the external fault according to the time sequence of events, and the time difference between each pair of voltage sag and fault in the matching result is calculated; s3, dynamically adjusting a window to calculate a quantile detection abnormal value; s4, performing secondary matching and iteration termination based on the reduced data set; and S5, repeating the steps S2-S4 for other monitoring points to obtain all matching data in the region, and realizing accurate positioning of the voltage sag source. According to the method, accurate and efficient fault positioning and matching can be carried out on the voltage sag event.

The invention discloses a bus fault analysis method and system for voltage sag, and relates to the technical field of bus fault analysis. The method comprises the following steps: synchronously acquiring three-phase voltage waveform data of a bus through a multi-source sensor, and obtaining a voltage sag event data set; performing sag feature extraction on the voltage sag event data set to generate a feature vector group; performing fault type identification according to the feature vector group in combination with a bus topological structure, and determining a fault judgment result; generating a dynamic reactive power compensation instruction based on the fault judgment result, performing adjustment through the dynamic reactive power compensation instruction to perform sag compensation on the bus voltage, and generating voltage compensation waveform data; and performing bus fault analysis according to the voltage compensation waveform data to generate a bus fault report. The technical problem that the bus fault analysis is not accurate enough in the prior art is solved, and the technical effect of improving the bus fault analysis accuracy is achieved.

The invention relates to the technical field of voltage sensitivity photovoltaic stability regulation and control of a power distribution network, in particular to a multi-parameter photovoltaic grid-connected voltage stability control method, system equipment and a medium, and aims to improve the transient modeling precision by constructing a second-order equivalent transient model of a photovoltaic system and decoupling a mapping relation between phase-locked loop parameters and equivalent inertia and damping; quantifying a transient stability boundary under voltage disturbance based on a phase-locked loop sensitive parameter, and determining a photovoltaic power angle critical safety threshold; for the whole voltage fluctuation process, dynamically and cooperatively regulating and controlling phase-locked loop parameters according to the voltage and frequency of the power grid; equivalent damping and inertia suppression oscillation are enhanced in the voltage drop period, inertia acceleration recovery is reduced while high damping is maintained in the voltage recovery period, rated parameters are reset in the steady state, the transient stability of the system for coping with voltage sag is remarkably improved, and the risk of power angle instability is avoided.

Disclosed is a method and system for SE voltage sag control based on flexible multiplexing of an energy storage system. The present disclosure achieves controlling of an early stage of the voltage sag using a supercapacitor, and continuous controlling of a late stage of the voltage sag using the energy storage system; achieves real-time accurate detection of the voltage sag on a grid side and a load side; achieves optimal energy compensation through flexible switching in an input stage and an output stage to prevent SE from tripping due to a phase jump caused by the optimal energy compensation; on a DC / DC side, performs power frequency division control based on a difference in response features between the supercapacitor and the lithium battery energy storage system; on a DC / AC side, provides a composite control system including a voltage feedforward loop, a voltage feedback outer loop, and a current feedback inner loop.

The invention discloses a relay protection equipment closed loop test method and system, and the method comprises the steps: adjusting the operation characteristic parameters of relay protection equipment based on the operation state monitoring information of a power system, so as to adapt to an instantaneous short-circuit current; according to a real-time load change condition, regulating and controlling a locking logic parameter so as to prevent premature tripping under a high-load condition; according to the amplitude and the duration of the voltage sag, the action threshold value of the protection device is dynamically adjusted so as to avoid maloperation or operation refusal caused by voltage fluctuation; and according to a communication network state evaluation result, optimizing received signal quality and time delay so as to ensure correct execution of a protection command. According to the invention, the operation characteristics of the relay protection equipment can be regulated and controlled according to the operation state of the power system, so that the problem of misoperation caused by instantaneous short-circuit current can be solved, and the locking logic parameters can be regulated and controlled according to the real-time load change of the power grid, so that the problem of premature tripping of the protection equipment under the condition of high load can be solved.

The embodiment of the invention discloses a waveform identification and correction method and system for winding deformation diagnosis, and relates to the technical field of transformer winding monitoring, and the method comprises the steps: synchronously collecting voltage and current signals, and carrying out the preprocessing; performing waveform disturbance type identification on the preprocessed signal, and dividing the disturbance type into harmonic dominant disturbance, voltage sag disturbance or compound disturbance, and harmonic dominant disturbance, voltage sag disturbance or compound disturbance; dynamically selecting a corresponding waveform processing path according to a waveform disturbance type identification result; processing the signal by adopting the selected waveform processing path so as to correct and reconstruct the signal and obtain compensated voltage and current waveform data; by constructing a disturbance identification and path adaptive processing mechanism, the problems of processing lag and compensation distortion of a general algorithm during dynamic signal disturbance are solved, the identification precision is improved, and real-time error correction is realized.

The invention belongs to the technical field of electric energy quality control, and provides an energy storage type medium-voltage voltage sag and interruption treatment device and a control method thereof.The energy storage type medium-voltage voltage sag and interruption treatment device is arranged between a large power grid and a load in series and comprises a series converter PCS1, a parallel converter PCS2, an energy storage module, an injection type series transformer T1, a parallel transformer T2, a bypass static switch STS and a bypass relay KM1; wherein the injection type series transformer T1 is connected with a large power grid, and the parallel transformer T2 is connected with a load; the series converter PCS1 is connected with the injection type series transformer T1 through the bypass static switch STS and the bypass relay KM1, and compensation voltage is generated in real time through the injection type series transformer T1; the parallel converter PCS2 is respectively connected with the parallel transformer T2 and the common direct current busbar; and the energy storage module is arranged on the common direct current busbar between the series converter PCS1 and the parallel converter PCS2 in parallel.

The invention discloses a three-phase uninterruptible power supply device and a control method thereof. The control method comprises the following steps: acquiring an input current of a three-phase alternating current power supply and a load voltage and a load current of an output end of an inverter circuit; carrying out harmonic separation on the collected input current, and determining a total harmonic distortion rate; when the total harmonic distortion rate is greater than a preset total harmonic distortion rate threshold value, generating a harmonic compensation signal; calculating load variation and voltage deviation based on load voltage and load current, dynamically adjusting proportional gain and integral time in real time, and generating a fundamental voltage control signal; superposing the fundamental wave voltage control signal and the harmonic compensation signal to generate a preliminary modulation wave; dynamically adjusting the dead zone time of the PWM wave, and combining the dead zone time with the preliminary modulation wave to generate the PWM wave; according to the control method, the three-phase alternating current is converted into the alternating current meeting the load requirement through the PWM waves, the response capacity to voltage sag, voltage fluctuation and harmonic disturbance is improved, and the output electric energy quality is improved.

The invention provides an optimal configuration method and device for a magnetic reactance type dynamic voltage restorer, and relates to the technical field of optimal configuration, and the method specifically comprises the steps: obtaining the historical voltage sag event data of a target power distribution bus and the electrical parameters of a downstream load motor; screening a to-be-compensated event set based on the principle that the sag depth exceeds a load tolerance threshold and the duration is less than the critical stall time, and determining a compensation strategy according to a comparison result of a phase jump angle maximum value and the threshold; the maximum compensation voltage is determined according to the maximum sag depth, the rated output current is determined according to the load parameters, the theoretical energy required for compensating the longest event is calculated based on the compensation strategy, and the actually required energy is determined in combination with the energy correction coefficient of the device topology; and finally, generating an optimal configuration scheme based on the compensation strategy, the maximum compensation voltage, the rated output current and the actually required energy. According to the invention, accurate mapping from power grid measured data to device key parameters is realized.

The invention provides a simulation method and system with controllable split-phase voltage drop time difference, and relates to the technical field of electric power testing, and the method comprises the steps: adjusting voltage through a three-phase voltage regulator, employing a bidirectional silicon controlled rectifier and IGBT hybrid switch structure to achieve voltage drop, collecting and processing a three-phase voltage signal through a digital signal processor, and extracting zero crossing point information; and a control pulse signal with phase compensation is generated, the conduction time sequence of the switch element is controlled to realize soft switching, and the industrial computer receives and processes the signal and displays a voltage drop waveform. The split-phase voltage drop time difference can be accurately controlled, and the simulation precision and the system reliability are improved.

The invention discloses an electric energy quality analysis method and system, and relates to the field of electric power monitoring, and the method comprises the steps: receiving electric energy monitoring message data through a DMA mode by using an SPI interface, and temporarily storing the received message data in an RAM; performing wavelet transform and FFT algorithm processing on the voltage and current signals of the electric energy monitoring message data; and analyzing electric energy quality parameters of the power grid, including voltage, frequency, voltage sag / rise, short-time interruption times, short-time and long-time flicker, harmonic waves and inter-harmonic waves, and displaying the parameters in a visual manner. According to the method, the measured parameter error is smaller, and the accuracy of electric energy quality analysis is improved.

The invention relates to the technical field of smart power grids, and provides a low-voltage power distribution network transparent fusion perception visual scene construction method and system, and the method comprises the steps: synchronously collecting voltage, current and equipment state data through power line carrier communication, a smart electric meter and a power distribution terminal, and building an annular queue with aligned time marks; a tree topology structure is constructed based on three-phase attributes, a connection matrix is generated, users are divided into visualization hierarchies with different transparencies through electrical distance calculation, and gradient coloring and special effect warning of an overload line are achieved in combination with current saturation mapping. The physical position and the electrical parameters are fused through polar coordinate system conversion, and a dynamic particle flow is generated to visually display current distribution; when the voltage sags, a voltage distortion propagation path is analyzed through waveform similarity backtracking, a disturbance source is positioned, and a pulse diffusion animation is triggered. Transparent fusion sensing of the running state of the low-voltage power distribution network, real-time early warning of line overload and second-level positioning of a disturbance source are achieved, and the intelligent operation and maintenance efficiency is improved.

The invention discloses a voltage sag detection method for a 0.4 kilovolt low-voltage power distribution network, and relates to the technical field of electric energy quality detection, and the method comprises the steps: collecting electric power data, calculating an instantaneous synchronization degree by using a cosine function, calculating an initial disturbance index by using a direct difference method, iteratively updating the disturbance index by using a weighted propagation iteration method, and constructing an updated disturbance vector. Generating a virtual sequence by using bitwise XOR operation, calculating a first-order difference of the virtual sequence, calculating a mean value, defining the mean value as a disturbance sensitivity index, regarding the disturbance sensitivity index as a scalar field, calculating vorticity of nodes, and defining the vorticity as global vorticity intensity; instantaneous phase difference of nodes is calculated by Hilbert transform, disturbance indexes are updated in combination with a cosine function and a weighted propagation iteration method, detection sensitivity and accuracy are improved, a mode of generating a virtual sequence through bitwise exclusive-or operation is introduced, global vorticity intensity is calculated in combination with connection weight between the nodes, and the detection accuracy is improved. And the precision and reliability of disturbance analysis are enhanced.

The invention relates to the technical field of energy storage technology and voltage sag treatment, and discloses an SE voltage sag treatment method and system based on flexible multiplexing of an energy storage system. A super capacitor is utilized to realize rapid treatment in the early stage of voltage sag, and energy of an energy storage system is utilized to realize continuous treatment in the later stage of voltage sag; a detection method for improving VMD based on TKEO and KC is provided, and real-time accurate detection of voltage sags on the grid side and the load side is achieved; optimal energy compensation is realized through flexible switching of the input and cut-out stages, so that the SE is prevented from jumping and stopping due to phase jump generated by the optimal energy compensation; power frequency division control is carried out on the DC / DC side according to the difference of response characteristics of the super capacitor and the energy storage system; on the DC / AC side, a composite control system comprising a voltage feed-forward loop, a voltage feedback outer loop and a current feedback inner loop is provided, the quick response capability and the anti-interference stability capability of the control system are improved, and a PIQR controller is adopted to eliminate the secondary influence of harmonic waves on the SE.

The invention relates to a modular intelligent power distribution cabinet safety management method based on the Internet of Things, particularly discloses a modular intelligent power distribution cabinet safety management method based on the Internet of Things, and aims to solve the problems that a traditional power distribution cabinet monitoring system is poor in expansibility, weak in fault recognition capability and rigid in protection strategy. The method comprises the following steps: deploying a modularized sensing unit with a standardized interface to realize plug and play; multi-dimensional data of current, voltage, temperature and arc light are synchronously acquired at a high sampling rate; data are fused on the edge side through Kalman filtering, and key features such as harmonic distortion rate, voltage sag depth, temperature gradient change rate and electric arc energy accumulation value are extracted; performing dynamic risk assessment by using a five-layer deep belief network model, and triggering early warning when the high risk probability exceeds a threshold value; adaptively adjusting an overcurrent protection constant value, opening delay and isolation logic according to an evaluation result; and the edge-cloud coevolution is realized by continuously optimizing the model and the strategy through cloud reinforcement learning.

The invention provides an intelligent dynamic voltage sag compensation control method and system. The method comprises the following steps: acquiring monitoring data from key nodes and equipment of a power grid, and uploading the monitoring data to a cloud for processing to obtain training data; establishing a power grid state prediction model by using deep learning, predicting a voltage trend and a sag occurrence probability through real-time monitoring data, obtaining voltage sag prediction data, positioning a potential source and analyzing a result; training a multi-device cooperative control strategy by adopting deep reinforcement learning, formulating an optimization scheme according to an analysis result, and generating a multi-device cooperative control scheme; and the distributed execution module is used for coordinating and adjusting equipment such as a transformer and a generator set to realize dynamic compensation of voltage sag. By adopting artificial intelligence and Internet of Things technologies, the intelligent and collaborative level is realized, and dynamic analysis, judgment, optimization and correction can be efficiently and accurately carried out on voltage sags of different types and time scales, so that the power grid compensation level is remarkably improved.

A power failure anomaly recognition method and apparatus. The method comprises: acquiring cluster data from a target cluster (S1); on the basis of the cluster data, acquiring distribution transformer data of each distribution transformer at each moment, the distribution transformer data comprising three-phase voltage imbalance, a three-phase voltage, the fluctuation amplitude of a phase current corresponding to voltage sag, a three-phase current, the sag amplitude of a three-phase instantaneous total active power, and the sag amplitude of each phase current (S2); on the basis of the distribution transformer data, screening out a corresponding distribution transformer that meets a first preset anomaly condition, so as to achieve preliminary anomaly recognition (S3); and, on the basis of the distribution transformer data, performing in-depth anomaly recognition on the distribution transformer that meets the first preset anomaly condition, so as to screen out a corresponding distribution transformer that meets a second preset anomaly condition and obtain a distribution transformer having power failure anomaly (S4). On the basis of the three-phase voltage imbalance, the three-phase voltage, the three-phase current and other distribution transformer data, preliminary anomaly recognition and in-depth anomaly recognition are performed; compared with manual inspection, the present method reduces manual workload and eliminates factors that affects power failure anomaly recognition such as limited human energy, thereby improving the timeliness and accuracy in power failure anomaly recognition.

The embodiment of the invention provides a method, a device, equipment and a product for generating voltage sag propagation characteristics of a power distribution network, and is applied to the technical field of power system automation. In response to a voltage sag event, acquiring an electrical parameter value of each current electrical connection point of the power distribution network and topological structure data of the power distribution network; wherein the topological structure data is used for indicating the connection relationship between the electrical connection points; generating a data characteristic matrix corresponding to the voltage sag event based on electrical parameter values of a plurality of electrical connection points and the topological structure data; inputting the data feature matrix into a pre-trained voltage sag positioning prediction model to obtain predicted fault positioning corresponding to the data feature matrix; and inputting the predicted fault location into a digital twinborn model corresponding to the power distribution network to obtain a propagation characteristic corresponding to the voltage sag event. The method achieves the technical effect of high voltage sag propagation characteristic determination efficiency.

The invention relates to a low-voltage ride-through control method for a network-forming converter based on key control parameters. The low-voltage ride-through control method comprises the following steps: step 1, designing an active and reactive self-adaptive updating method during voltage sag; 2, introducing a virtual inductor Lv to carry out linear correction on a reactive power regulation coefficient x; 3, based on the improved virtual damping Dp, the transient state power angle stability of the network construction type converter system of the VSG architecture is enhanced; the filtering time constant Ts of damping is improved, and the variable damping gain Dp'changes the static-dynamic power angle stability of the grid-forming converter; and step 4, improving a reactive voltage regulation link of the network construction type converter by improving a reactive integral channel. According to the method, from the two aspects of power closed-loop control and synchronous stable control, the severity of a fault is judged by detecting the amplitude of an output voltage, and meanwhile, active and reactive power reference values are adaptively changed to realize power closed-loop control. And the reliability and the stability of voltage control in the transient process are jointly improved.

The invention relates to a magnetic control fast switch and dynamic voltage restorer combined power supply switching system and method. The system comprises a magnetic control switch unit, a voltage monitoring unit, a voltage compensation unit and an arc extinguishing unit. The magnetic switch unit is made of a novel magnetic control material and forms a vertical motion opening and closing mechanism through excitation and demagnetization of a built-in coil and assistance of a spring, and the vertical motion opening and closing mechanism is used for changing an internal magnetic domain and rapidly opening and closing. The voltage detection unit adopts a double-second-order generalized integral phase-locked loop voltage monitoring structure and is used for detecting instantaneous phase and frequency information of power grid voltage; the voltage compensation unit adopts a dynamic voltage restorer and is used for performing voltage compensation according to a difference value between a current power supply and an objective table power supply in a power supply switching gap so as to effectively maintain the stability of load voltage when voltage sag occurs in a power grid; and the arc extinguishing unit adopts a T-shaped double-outlet vacuum arc extinguishing chamber and is used for realizing zero arc in the whole power supply switching process. According to the invention, rapid switching of the power supply can be realized, and continuous voltage is ensured in the switching process.

The invention relates to the technology of power electronics and electric energy quality control, in particular to an energy storage type UPQC and switch state prediction control method based on improved model prediction control, which comprises a series active filter, a parallel active filter, a direct current bus, an energy storage system and a controller, according to the control method, an energy storage power and charge state dynamic equation is introduced into an MPC prediction model, and a multi-objective cost function is designed. And the controller predicts and evaluates the candidate switching vector in each sampling period based on a finite control set model predictive control strategy, and outputs an optimal switching state through value function optimization, thereby realizing collaborative optimization of electric energy quality management and energy storage energy management. According to the method, the dynamic response capability and compensation precision of the UPQC under the working conditions of voltage sag / sag, imbalance, harmonic waves and load fluctuation are remarkably improved, meanwhile, the energy storage utilization efficiency and the system stability are improved, and the method is suitable for a power distribution network with new energy high permeability and large load fluctuation.

The invention discloses a power grid voltage sag detection method based on improved discrete Fourier transform, and belongs to the field of power quality detection, and the method comprises the steps: S1, converting a three-phase power grid voltage signal under a three-phase static coordinate system (a, b, c) into a two-phase static coordinate system (alpha, beta) through 3s / 2s coordinate transformation; s2, enabling the voltage signal under the coordinate system (alpha, beta) to sequentially pass through a comb filter Gf (z), a resonator # imgabs0 # and an adjustment factor Ga (z) so as to obtain a phasor signal of a positive sequence fundamental frequency component; and S3, calculating the mode length of the positive sequence fundamental frequency component phasor signal to obtain the amplitude of the positive sequence fundamental frequency voltage, and comparing the amplitude with a power grid voltage sag detection threshold to judge whether the power grid voltage sags or not. According to the algorithm provided by the invention, the accurate detection of the voltage sag event of the power grid can be realized under the non-ideal power grid condition of harmonic distortion and three-phase voltage imbalance.