163 results about "Voltage sag" patented technology

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.

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 utility model provides a voltage sag resistant circuit and a motor, the circuit comprises an energy storage module, the energy storage module comprises a first capacitor, a second capacitor, a first diode, a second diode and a third diode, the second end of the first capacitor is connected to the cathode of a first diode, and the anode of the first diode is grounded; the cathode of the second diode is connected to the energy exchange end of the circuit, the anode of the second diode is connected to the first end of the second capacitor, and the second end of the second capacitor is grounded; the anode of the third diode is connected between the first capacitor and the first diode, and the cathode of the third diode is connected between the second diode and the second capacitor. According to the anti-voltage sag circuit and the motor, the motor can be kept running continuously when voltage sag occurs. In addition, the circuit and the motor are small in size and low in cost, and the power factor of the system can be improved.

The invention discloses a multi-mode fault ride-through control method of a network-forming type energy storage converter, which relates to the technical field of converter control and comprises the following steps of: acquiring node voltage amplitude, voltage phase angle, system frequency and harmonic component, and filtering acquired data; according to the method, the operation region is calculated based on the real-time filtering data, the electromagnetic transient energy and the rotation kinetic energy component, so that the network-forming type energy storage converter intelligent body at different spatial positions can obtain differentiated control margins during the fault period; the operation area of the network-forming energy storage converter intelligent body which is close to a fault point and is seriously influenced by voltage sag or frequency fluctuation can automatically contract during a fault period; the operation area of the network-forming type energy storage converter intelligent body which is far away from the fault point and is slightly disturbed by the fault is kept relatively loose, and the technical problems that control close to the fault point is insufficient and control resources far away from the fault point are wasted due to one-time cutting of a traditional fixed operation area are effectively solved.

The invention relates to the technical field of electric energy quality treatment, in particular to a collaborative treatment system and method based on multi-class electric energy quality adjustment resources. The system comprises an electric energy quality disturbance generation device, an electric energy quality interference source device, a harmonic current generation device, a line impedance simulation device, a data acquisition device, an electric energy quality diagnosis module and a coordinated scheduling module. According to the invention, independent or coupled simulation of various disturbance types such as voltage sag, harmonic wave, imbalance and flicker is supported based on various types of power quality regulation resources, optimal scheduling and cooperative control of various types of regulation resources such as source, network and load are realized, modular design is realized, plug and play and test verification of various treatment devices are supported, and the power quality regulation system is suitable for large-scale popularization and application. Through line impedance simulation and multi-working-condition setting, an actual power grid operation environment is approached, and the system is especially suitable for a high-proportion new energy and power electronic equipment access scene.

The invention discloses a power distribution network voltage sag monitoring point multi-target selection method considering a distributed power supply low voltage ride through characteristic. The method comprises the following steps: providing a distributed power supply low voltage ride through strategy; deriving a voltage sag amplitude analytical expression under various short circuit fault types considering the low voltage ride through characteristic of the distributed power supply; introducing a position variable to construct a function relation between a voltage sag amplitude and a fault position; solving a voltage sag domain critical point by using a differential evolution algorithm; based on the sag domain critical point, establishing a monitoring point multi-target selection model taking economical efficiency, redundancy and construction urgency minimization as a target function; solving the established monitoring point multi-target selection model by adopting a multi-target particle swarm algorithm to obtain a Pareto optimal solution set; and according to the obtained Pareto optimal solution set, adopting an ideal point method to screen out an optimal point distribution scheme. According to the method, the voltage sag domain can be accurately divided, and multi-objective optimization of economical efficiency, low redundancy and low construction urgency of monitoring point layout is realized on the premise of satisfying panoramic observability.

A voltage sag homologous identification method and system based on association rule mining, relating to the technical field of power quality mitigation. Transactions are formed by means of screened candidate homologous sag events, a transaction table is formed, a plurality of frequent itemsets are screened on the basis of the support of each itemset in the transaction table, so as to construct a canonical-order tree corresponding to the transaction table, thereby reducing the number of misleading transactions and improving the effectiveness of voltage sag homologous identification. In addition, association rules for candidate homologous sag events corresponding to every two frequent itemsets are determined by means of the canonical-order tree, waveform similarity comparison is performed on voltage waveforms corresponding to the candidate homologous sag events, and whether the two candidate homologous sag events are homologous sag events is determined, thereby improving the accuracy of voltage sag event homologous identification.

A transient stability control method and apparatus for a wind-thermal-bundled system. The method comprises: acquiring in real time terminal voltage of a doubly-fed induction generator when the wind-thermal-bundled system experiences a fault (S1); in response to the terminal voltage of the doubly-fed induction generator being within a first voltage sag interval, increasing a reactive current injection coefficient of the doubly-fed induction generator on the basis of a preset adjustment rule, to reduce the swing amplitude of a synchronous generator during an acceleration phase under fault conditions (S2); in response to the terminal voltage of the doubly-fed induction generator being within a second voltage sag interval, increasing the reactive current injection coefficient of the doubly-fed induction generator on the basis of the adjustment rule, to reduce the swing amplitude of the synchronous generator during the acceleration phase and the swing amplitude thereof during a deceleration phase under fault conditions (S3); and in response to the terminal voltage of the doubly-fed induction generator being within a third voltage sag interval, decreasing the reactive current injection coefficient of the doubly-fed induction generator on the basis of the adjustment rule, to reduce the swing amplitude of the synchronous generator during the deceleration phase under fault conditions (S4).

The invention discloses a power grid voltage stability evaluation method and system, which are applied to the field of voltage stability evaluation, and the method comprises the steps: determining a low-frequency component and a high-frequency component of each node of a target power grid; voltage sag information of the corresponding node is obtained; determining a first target node according to an analysis result of the voltage sag information; determining a high-frequency modeling mode of each node based on the voltage sag information; analyzing the high-frequency component, and determining a target frequency band; in the target frequency band, determining the corresponding node as a second target node based on an analysis result of the high-frequency operation model; and obtaining a stability evaluation result of the target power grid based on the first target node, the second target node and the topological information, and at least adjusting the switching group number of the parallel capacitor group of the target power grid according to the stability evaluation result. The power grid voltage stability assessment method and system provided by the invention can accurately assess the power grid voltage stability and provide an accurate basis for the control of the power grid voltage.

The invention relates to a GAT-based industrial user voltage sag sensitivity degree evaluation method and equipment, and the method comprises the steps: obtaining the characteristics, types and equipment connection relations of sensitive equipment influenced by voltage sag, constructing a topological graph, inputting the topological graph into a trained graph attention neural network, outputting a voltage sag sensitivity evaluation result, and carrying out the evaluation of the sensitivity degree of the industrial user voltage sag. Wherein the graph attention neural network is constructed by embedding a GAL layer in a message passing graph neural network, the GAL layer calculates an attention coefficient between nodes in a topological graph by using an attention mechanism, weighted aggregation is performed by using an update function, iterative update of node features is completed, and a voltage sag sensitivity evaluation result is finally mapped and output. Compared with the prior art, the method has the advantages of improving the evaluation accuracy and the like.

The invention relates to the technical field of electric power systems, and discloses a voltage sag source identification method, system and device, a medium and a product, and the method comprises the steps: obtaining a voltage sag waveform at a preset measurement point on a power grid line, extracting the frequency domain characteristics and time domain characteristics of the voltage sag waveform, and carrying out the recognition of a voltage sag source based on an attention mechanism; and performing weighted fusion on the frequency domain features and the time domain features, inputting weighted feature vectors into a plurality of pre-trained classifiers based on a KAN network, outputting sub-classification results of the plurality of voltage sag sources, and fusing the sub-classification results of the plurality of voltage sag sources to obtain a classification result of the voltage sag sources. Therefore, the internal association of the voltage sag source among different levels is effectively mined by using the strong nonlinear fitting capability of the KAN network and a feature sharing mechanism under a multi-task learning framework, the adaptability and classification precision of the model to a complex disturbance scene are improved, and the accuracy and reliability of voltage sag source identification are improved.

The invention provides a cooperative low-voltage ride-through control method and related device based on a network construction type and network following type three-terminal interconnection system, and the method comprises the steps: triggering a cooperative low-voltage ride-through control mechanism in response to a voltage drop fault generated at an AC side connected with a network construction type converter; performing cooperative control on each converter based on the mechanism; wherein the control network construction type converter only undertakes AC side voltage establishment and current safety survival functions, realizes current limiting control through adaptive virtual impedance, and does not participate in DC side energy adjustment of a common DC bus; the DC voltage control type grid-following converter is controlled to suppress DC voltage double-frequency fluctuation of the common DC bus, and actively absorb and compensate double-frequency power disturbance introduced by the grid-forming converter; and controlling the active power control type grid-following converter to avoid active power adjustment during the voltage drop fault period. A collaborative low-voltage ride through control mechanism is provided, the direct-current voltage fluctuation is reduced, and the overall low-voltage ride through capacity of the system is improved.

This invention provides a fault early warning method for low-voltage power distribution systems in smart factories, belonging to the field of low-voltage power distribution fault early warning technology. Based on the low-voltage power distribution system topology, it deploys synchronous current and voltage acquisition terminals and ambient temperature sensors to acquire real-time current waveforms, voltage sag events, neutral current values, and ambient temperature for each circuit. The real-time current waveforms are decomposed into harmonic sequences using Fourier transform, generating a harmonic spectrum distribution matrix. A joint probability table of voltage sag and neutral overcurrent events is constructed by correlating timestamps. Combining the harmonic amplitude growth trend with the characteristics of coupled events whose joint occurrence probability exceeds a set threshold, a candidate circuit set for insulation degradation risk is screened, and temperature field inversion calculation is performed to generate a conductor surface temperature rise distribution map. This method can quantify the temporal coupling relationship between the two types of events, narrowing the fault investigation scope, reducing false alarms and missed detections, accurately reflecting the insulation degradation state of the circuits, and achieving accurate fault early warning for low-voltage power distribution systems.

The invention discloses a multi-source sequence distribution network anomaly diagnosis method and system based on covariance regularization segmentation. The method comprises the steps of obtaining data of electrical indexes of various sources of a specified transformer and constructing a multi-source sequence; normalizing the multi-source sequence to obtain a preprocessed multi-source sequence; carrying out covariance regularization iteration segmentation on the preprocessed multi-source sequence so as to adaptively divide the preprocessed multi-source sequence into a plurality of state segments with the strongest internal homogeneity and obvious boundary difference; and extracting the segment statistical characteristics of each state segment to map and obtain the distribution network anomaly type of the specified transformer. The method aims to solve the problems of concealment, high-dimensional coupling and real-time performance of anomaly detection in transformer area multivariable power data, complex abnormal events such as voltage sag, interphase short circuit and harmonic pollution are accurately captured from the perspective of statistical characteristic abrupt change, and detection precision and edge calculation efficiency are both considered.

The application discloses a voltage sag identification method based on a triple tuple prototype network under a small sample, and belongs to the technical field of power quality analysis. The method uses a triple tuple feature extractor, a large number of voltage sag triple tuples are constructed, and effective sag features can be extracted by the model under the condition of a small number of training samples. Then, in view of the problem that some voltage sag features are similar and easy to confuse, an efficient channel attention mechanism is integrated into the triple tuple feature extractor, cross-channel feature interaction information is captured under the condition of only a small number of parameters, the model can pay attention to the key feature area, a prototype classifier is finally constructed, representative class prototypes are learned for each class by using the extracted sag features, and the final sample class is determined by comparing the similarity between sample features and class prototypes. Under the condition of limited sample data, the method can realize accurate voltage sag classification effect, and has strong practical application significance.

The application provides a non-delay voltage sag method and device, and relates to the technical field of intelligent control. When a voltage sag is caused by a fault on a power grid side, an energy storage device automatically injects current to the power grid side through a reactor, a voltage drop is formed on the reactor, and the voltage on the load side is ensured to be stable. While the voltage sag is treated, a total control device CCU monitors the duration of the voltage sag on the power grid. If the duration exceeds a preset delay constant, it is determined that the fault is persistent, a control signal is output, a power grid side switch S1 of each energy storage unit is tripped, the injection of current to the fault power grid is cut off, and the load is supported by the energy storage device T alone. When a slight voltage sag occurs on the power grid side, the load does not need to be cut off from the power grid, and the treatment is truly non-delay.

The invention relates to the technical field of new energy power generation, in particular to a voltage sag treatment system for a new energy power system and an application method, the method comprises a voltage rapid recovery device, the voltage rapid recovery device comprises a rapid switch and an isolation impedance, and the rapid switch and the isolation impedance are connected in parallel; a parallel circuit formed by the high-speed switch and the isolation impedance is connected in series in a power transmission line of the new energy power system; when the new energy power system operates normally, the quick switch is switched on, and when the new energy power system has a short circuit fault and causes voltage sag, the quick switch is switched off within a preset time so as to connect the isolation impedance into the power transmission line. And raising the terminal voltage of the new energy unit in the new energy power system during the short-circuit fault through the isolation impedance. When the new energy power system has the voltage sag caused by the short-circuit fault, the voltage boosting efficiency and reliability are improved.

The invention provides a method and a device for relieving voltage sag of an active power distribution network based on two-stage partition. The method comprises the following steps: determining node voltage and line impedance parameters of a bus based on network topology and element parameters of the active power distribution network; constructing an electrical connection matrix based on the line impedance parameters; determining a swing radius index based on the electrical connection matrix and the node voltage; constructing a sensitivity matrix, and combining the swing radius index to construct a lambda matrix; determining an M index according to the lambda matrix, and performing partitioning in combination with the feature boundary to obtain a first partitioning result; performing weighted smoothing on a lambda sequence in the lambda matrix through a kernel smoothing function, and performing partition boundary correction on the first partition result based on the smoothed lambda distribution to obtain a second partition result; and selecting a key node to configure a dynamic voltage restorer DVR according to a second partitioning result, so as to control the dynamic voltage restorer DVR to inject a compensation voltage to an access bus when a voltage sag event occurs, thereby realizing the alleviation of the voltage sag of the active power distribution network.

The application discloses a capacitor energy storage control method and system, and belongs to the technical field of energy storage control, which comprises phase change material residual heat preservation heat evaluation, capacitor module emergency support energy calculation, capacitor module charge and discharge current adjustment, closed loop control and parameter iteration, and through collection of multi-physical quantity data of the phase change material, the capacitor module and the power grid, the phase change material heat preservation capacity is evaluated, the capacitor emergency support energy is calculated, the charge and discharge current is adjusted in combination with voltage sag prediction, and dynamic balance of heat preservation and power grid support is realized. Through the phase change material residual heat preservation heat evaluation, the application provides key temperature boundary conditions for subsequent energy calculation, deeply couples the phase change material heat preservation capacity and the capacitor electrical performance, and in combination with the closed loop control and the parameter iteration, a closed loop control chain of temperature, energy and current is formed, coordinated control of various modules is realized, the ability of the system to cope with complex working conditions is improved, and long-term stable operation of the capacitor energy storage system is ensured.

The invention discloses a capacity optimization configuration method, system and platform for a multi-mode flexible power distribution network power supply device based on hybrid energy storage, and the method, system and platform achieve the comprehensive improvement of the power quality of a power distribution network through the network construction / network following multi-mode cooperative control and the dynamic optimization distribution of the hybrid energy storage. The device adopts accurate power adjustment guided by the storage battery under a normal working condition; under emergency working conditions of voltage sag and the like, a super capacitor is switched to support preferentially, and uninterrupted power supply of a key load is guaranteed. By establishing a technology-economy double-layer optimization model and adopting an improved Hemma optimization algorithm to carry out capacity configuration, the capacity demand of the converter is reduced, the utilization rate of an energy storage system is improved, the comprehensive cost of the whole life cycle is reduced, and the technical contradiction that the dynamic response speed and the economy are difficult to consider in a traditional scheme is successfully solved.

The invention relates to the technical field of power system automation and electric energy quality control, in particular to an electric energy quality optimization control method and system based on distributed collaborative decision. The method comprises the following steps: deploying synchronous phasor measurement units and corresponding edge intelligent decision nodes at a plurality of nodes of a power grid, and constructing a distributed network; each node calculates an electric energy quality characteristic index based on local data; dynamic role negotiation is carried out through local communication, and a leading controller is determined; the dominant controller fuses strategies and confidence information of local and adjacent nodes to generate a cooperative control strategy; and finally, equipment such as a static var generator and an active power filter is controlled to perform coordinated execution. Through a decentralized collaborative decision-making mechanism, the defects that centralized control is slow in response and low in reliability are overcome, rapid self-adaptive treatment on voltage sag, harmonic waves and other problems is achieved, and the response speed, the treatment success rate and the system robustness are remarkably improved.

The application discloses a voltage sag region online identification method and system based on a dynamic fuzzy rule base, and belongs to the field of power system power quality analysis and protection. The method comprises the following steps: calculating initial voltage sag critical points on each line in a power system to generate an initial voltage sag region AOV; acquiring voltage amplitude deviation, phase jump rate and fault point electric distance data of a load point, and performing fuzzy processing on the data by using a membership function to obtain a membership set, inputting the membership set into a TSK fuzzy reasoning model based on a dynamic updating rule base to output a critical point correction amount; and adaptively updating a region boundary according to the initial voltage sag critical points and the critical point correction amount to output an accurate voltage sag region. By introducing a dynamic fuzzy reasoning and online updating mechanism, the application effectively improves the accuracy and adaptability of voltage sag region identification, and solves the problems that existing methods cannot comprehensively consider multiple influence factors and lack online updating capability.

The utility model discloses a direct-current self-starting circuit for a voltage sag treatment device. The direct-current self-starting circuit comprises a thyristor bypass module, a monitoring module, a DVR module and a super capacitor, the thyristor bypass module comprises a thyristor device, a DSP master controller, a driving circuit, a bypass auxiliary power supply, an overcurrent protection circuit, a first relay, a bias holding circuit, a switch, a timing circuit, a first optocoupler and a second optocoupler; the monitoring module is connected with the bypass auxiliary power supply; the DVR module comprises a DC / DC power converter connected with the super capacitor and the monitoring module, an inverter bus connected with the DC / DC power converter, an inverter, an auxiliary power supply connected with the DC / DC power converter and the super capacitor, and a second relay; the second relay is connected with a second optocoupler and a bypass auxiliary power supply; the super capacitor is connected with the first relay.

Embodiments of the present disclosure provide a method and a device of controlling a power supply circuit, a non-volatile readable storage medium, and an electronic device. The method of controlling a power supply circuit includes: detecting whether a voltage value of an input voltage of the power supply circuit drops; when detecting that the voltage value of the input voltage drops, determining a target drop percentage of a current voltage value of the input voltage relative to a normal voltage value of the input voltage after the voltage value of the input voltage drops and a first duration in which the voltage value of the input voltage is at the current voltage value; judging whether the target drop percentage and the first duration meet a preset voltage sag judgment condition; and when judging that the target drop percentage and the first duration meet the preset voltage sag judgment condition, determining that the input voltage of the power supply circuit undergoes a voltage sag, and performing a target protection operation on the power supply circuit.

The invention provides a power grid fault position detection and diagnosis method, which comprises the steps of collecting current amplitude and phase from each section in a power distribution feeder, extracting voltage sag depth distribution from each position of the feeder, obtaining reactive power output force value from a distributed power supply grid-connected point, and obtaining comprehensive fault measurement information; positioning and identifying the distance between a grid-connected position and a fault point according to the current reversal amplitude and the flow direction of a downstream section, evaluating and correcting the influence of reactive power output on voltage sag, and identifying atypical sag response caused by reactive power reverse transmission; and according to the identified atypical sag response, correcting the original fixed action threshold value of the directional element and the voltage phase offset caused by the current reactive power output, and obtaining an optimized threshold value by integrating the current reversal amplitude and the voltage sag depth.

The invention discloses a large signal stability analysis method for a dual-power-supply cascaded power electronic transformer, which relates to the technical field of power electronics and comprises the following steps: establishing a state space averaging model of the dual-power-supply cascaded power electronic transformer; according to the state space averaging model of the dual-power-supply cascaded power electronic transformer, constructing a mixed potential function of the dual-power-supply cascaded power electronic transformer; and performing analysis based on the mixed potential function of the dual-power-supply cascaded power electronic transformer in combination with a large signal stability criterion to obtain a large signal stability analysis result of the dual-power-supply cascaded power electronic transformer. According to the method, the stability domain of the dual-power-supply cascaded power electronic transformer in large disturbance scenes such as voltage sag and power abrupt change can be analyzed, and the influence of alternating current system parameters, power electronic transformer hardware parameters and controller parameters on the stability domain can be analyzed accordingly.

In view to the treatment of voltage quality problem under the influence of power fluctuation of power grid, the application discloses a control and design method of energy storage type power quality treatment device with multi-mode access, and the capacity total of energy storage type power quality treatment device under the same voltage sag compensation requirement is reduced through the complementation of functions of energy storage type power quality treatment devices with two different access modes. For this purpose, firstly, a mathematical model of power grid voltage sag under load side power fluctuation is established, the voltage compensation of series type energy storage and the power compensation of parallel type energy storage are cooperatively controlled, the optimal configuration ratio of energy storage type power quality treatment device is designed according to the power grid and load working condition, and the total amount of energy storage type power quality treatment device to be determined for voltage compensation is obtained according to the analysis of the mathematical model of power grid voltage sag. The method can reduce the overall design capacity of energy storage type power quality treatment device, improve the utilization rate of energy storage unit, and improve the economy of power grid voltage sag compensation.

The invention discloses a power distribution network voltage sag sag domain analysis method considering distributed power supply access, and relates to the technical field of power system electric energy quality control. According to the method, a power distribution network asymmetric short circuit three-sequence equivalent model containing a distributed power supply and sensitive equipment is constructed, a looped network is split based on a voltage lowest node when a looped network structure exists, and a voltage sag sag domain general equation and a characteristic equation under any line fault condition are established; and further through sag subsystem division and Kron order reduction processing, an order reduction node impedance matrix about fault position parameters is formed, and the fault position parameters enabling the residual voltage of the sensitive nodes to reach a preset threshold value are determined by adopting an optimization iteration mode, so that the voltage sag sag domain boundary is accurately obtained. The method can give consideration to the calculation precision and efficiency, and is suitable for the voltage sag analysis of the power distribution network containing the distributed power supply and the complex topological structure.

The utility model discloses a kind of dual-axis vibration sensor circuit with redundant signal output, including power supply VCC, power voltage detection chip U2, independent power supply U3, independent power supply U4, dual-axis vibration chip U5, dual-axis vibration chip U6, signal follower IC1, signal follower IC2, analog switch U1, independent power supply U3, independent power supply U4 are internal power supply of dual-axis vibration sensor, respectively power supply dual-axis vibration chip U5, dual-axis vibration chip U6, when one of power supply is abnormal, another signal normal output will not be affected. Analog switch U1 exports X or Y direction signal. The output of analog switch U1 is controlled by power voltage detection chip U2, when power supply voltage is lower than or higher than certain set value, analog switch automatically exports corresponding dual-axis vibration chip U5 or dual-axis vibration chip U6 sensor signal, entire circuit can be used in voltage fluctuation larger or voltage sag more frequent occasion, ensure that sensor can normally output.

The invention relates to a network construction type MMC supporting capacity improving method considering power grid voltage sag, and belongs to the field of power electronic converter optimization control. The method comprises the following steps: firstly, initializing an operation condition and calculating a steady-state electrical quantity; when out-of-limit occurs, introducing a collaborative optimization strategy of double complementation of double frequency multiplication circulating current and a zero sequence signal, and solving an optimal parameter meeting physical limitation; global optimization is carried out by traversing boundary conditions, and a mapping table of multi-dimensional operation conditions and optimization parameters is generated; and then fitting the table by using a neural network, generating a prediction model and deploying the prediction model in a controller. When voltage drop occurs in the power grid, the controller can directly output an optimized injection instruction within millisecond according to real-time working conditions. According to the method, complex online iterative calculation is abandoned, the safe operation boundary of the MMC is effectively widened on the premise that the hardware cost is not increased, and the supporting capacity and the system stability of the network construction type MMC in the power grid fault period are improved.