284 results about "Grid impedance" patented technology

The invention relates to the technical field of energy storage power station combined operation and maintenance management, and provides a virtual power plant-oriented energy storage power station combined operation and maintenance management system, which comprises a dynamic sensing module for acquiring battery cluster temperature difference distribution, power converter switch transient characteristics and grid-connected point harmonic spectrum data of an energy storage power station in real time through a multi-dimensional sensor network; the collaborative decision-making module is used for dynamically generating a cross-station power interaction constraint rule based on the virtual power plant topological structure; the impedance reconstruction module adjusts the equivalent output impedance of the energy storage converter in real time according to the impedance characteristics of the power grid; the state balancing module is used for realizing charge state dynamic balance and power margin collaborative distribution among the multiple energy storage power stations; and the secure communication module is used for ensuring secure transmission of control instructions among the modules by adopting a layered encryption protocol. The operation stability, the power distribution flexibility and the equipment safety of the virtual power plant can be improved, and the service life of the energy storage equipment is prolonged.

The invention provides a virtual synchronous generator adaptive control method based on line impedance identification, and relates to the technical field of power system control. The line impedance identification-based adaptive control method for the virtual synchronous generator comprises the steps of dynamically adjusting the virtual inertia J, the damping coefficient D and the droop coefficient K of the virtual synchronous generator through a multivariable constraint optimization algorithm according to the impedance-frequency coupling model, and realizing real-time matching between the output power of the virtual synchronous generator and the impedance of a power grid. By collecting power grid signals in real time and extracting impedance characteristics, the dynamic change of power grid impedance can be timely and accurately mastered, and a reliable basis is provided for subsequent control strategy adjustment, so that real-time matching of the output power of the virtual synchronous generator and the power grid impedance is realized, power fluctuation is effectively reduced, and the stability of a power grid is improved; according to the invention, a self-adaptive modulation strategy and a multi-resonant controller are adopted, harmonic oscillation can be effectively suppressed, and the quality of output electric energy of the inverter is improved.

The invention discloses a network-following flexible switching prediction control method and system for a grid-connected converter, and the method comprises the steps: calculating a short-circuit ratio according to obtained power grid impedance data, and if the short-circuit ratio is smaller than a switching threshold value, indicating that the power grid strength is reduced, and otherwise, indicating that the power grid strength is not reduced. At the moment, a prediction control reference current in the switching process is calculated through an adaptive switching function in a first switching function form and a current reference value in a grid following mode and a grid construction mode, and the grid-connected converter is switched from the grid following mode to the grid construction mode; and otherwise, indicating that the power grid intensity is increased, calculating a prediction control reference current in a switching process through an adaptive switching function in a second switching function form and a current reference value in a grid following mode and a grid construction mode, and switching the grid-connected converter from the grid construction mode to the grid following mode. Therefore, according to the adaptive switching function-based network-following flexible switching prediction control method, rapid and flexible switching of the grid-connected converter module is ensured, and the stability and the grid-connected output efficiency of the converter in the new energy grid-connected power generation system can be effectively improved.

The invention belongs to the technical field of optical storage cooperative control, and discloses a new energy grid-connected optimization control method based on an energy storage system, which comprises the following steps: collecting a power grid impedance fluctuation amplitude, a harmonic distortion rate and environment temperature data, obtaining an initial SOC value, correcting the SOC value, calculating an adjustable power margin and a response delay parameter of a photovoltaic unit, and calculating the optimal power grid impedance fluctuation amplitude and the optimal power grid impedance fluctuation amplitude. Generating an efficiency responsibility table; constructing a response cluster, generating a frequency modulation task package, and further generating a three-dimensional efficiency mapping table; the inertia demand is dynamically calculated in combination with the power grid frequency change rate, a responsibility transfer strategy is automatically activated in a high-altitude and high-temperature scene, and an efficiency instruction set is generated; analyzing response deviation by simulating typical disturbance of a high-altitude weak power grid scene, positioning a deviation source in combination with historical data, and dynamically adjusting an efficiency weight correction factor; and updating a responsibility allocation rule of the efficiency responsibility table, disrupting the low-efficiency cluster, and recombining the high-adaptability unit.

Aiming at the stability problem caused by harmonic resonance of multiple parallel photovoltaic inverters, the invention provides a parallel inverter micro-grid-oriented adaptive virtual impedance remodeling harmonic resonance suppression method, which comprises a virtual impedance remodeling unit of a grid-connected inverter, a parameter adaptive adjustment unit and a power grid impedance online detection unit. The virtual impedance remodeling unit can improve the output impedance characteristic of the grid-connected inverter and inject a certain damping component into the micro-grid; and the parameter adaptive adjustment unit adaptively adjusts control parameters in the virtual impedance remodeling unit and the current adjustment controller according to the impedance parameters of the power grid so as to maintain the stability of a system control loop. The power grid impedance online detection unit provides power grid equivalent impedance as the input of the parameter adaptive adjustment unit. The three units work cooperatively to form a self-adaptive virtual impedance remodeling multi-inverter micro-grid harmonic resonance suppression strategy, so that the characteristics of a current loop are improved, the inverters can be kept stable under various grid impedance conditions, and the reliability of a multi-inverter micro-grid system is improved.

The invention relates to the technical field of grid-connected converters, and particularly discloses a grid-connected converter self-adaptive grid-following and grid-constructing hybrid control method and system, and the method comprises the steps: calculating d-axis and q-axis grid-following modulation signals and a grid-following phase angle in a grid-following control part; in a network construction control part, network construction modulation signals and network construction phase angles of a d axis and a q axis are calculated; performing angle weighting on the network following phase angle and the network construction phase angle to generate a hybrid control phase angle; weighting the d-axis and q-axis network-following modulation signals and the d-axis and q-axis network-constructing modulation signals to obtain a hybrid control modulation signal; performing coordinate transformation and PWM (Pulse Width Modulation) on the phase angle of the hybrid control and the modulation signal of the hybrid control to obtain a switching control signal of the grid-connected converter of the hybrid control; the weight of the modulation signal can be dynamically adjusted along with the change of the real-time power grid impedance, so that the converter preferentially tracks a power instruction to realize the maximum output in a strong power grid working condition, and actively enhances the voltage / frequency supporting capability in a weak power grid working condition.

The invention discloses a main power grid short-time load prediction method using a hybrid active filter, and particularly relates to the technical field of load prediction. The method comprises the following steps: acquiring active control parameters and passive branch parameters of a hybrid active filter, combining a real-time load fluctuation signal of a main power grid, extracting harmonic suppression characteristics and phase distortion characteristics, and analyzing and generating a time scale compensation factor through a dynamic coupling effect; and constructing a phase correction model based on the transient harmonic residual component and the time scale compensation factor, and performing frequency domain and time domain combined reconstruction on the real-time load fluctuation signal to obtain a corrected load fluctuation characteristic sequence. A short-time load prediction model is calibrated through a collaborative mapping relation, a load power prediction value of a main power grid in a future preset time window is output, a secondary high-frequency interference signal generated by real load fluctuation and filter self-resonance is effectively distinguished, and the problem of coupling interference of harmonic residual components on the load prediction model in a power grid impedance sudden change scene is solved.

The invention relates to an impedance measurement method and system. The method comprises the following steps: acquiring grid-connected point voltage, measurement frequency, disturbance amplitude and nth inverter grid-connected current of the multi-inverter grid-connected system; inputting the grid-connected point voltage into an improved phase-locked loop in a fundamental wave and disturbance control unit to generate a power grid frequency and a power grid phase; inputting the power grid phase and the nth inverter grid-connected current into the current control loop to generate a fundamental current control instruction; inputting the measurement frequency, the disturbance amplitude and the power grid frequency into the disturbance control ring to generate a disturbance instruction; inputting the disturbance instruction and the fundamental current control instruction into the modulation ring, generating a control driving signal according to a modulation strategy of an inverter, and controlling each inverter switch; and obtaining the controlled grid-connected point voltage through an impedance calculation unit, and generating the impedance of the inverter to be tested and the impedance of the power grid. By adopting the method, disturbance can be injected efficiently at low cost so as to measure impedance.

The invention provides a power grid connection disturbance observer feedback control method, which belongs to the technical field of power grid connection, and comprises the following steps: detecting power grid impedance parameters by using a multi-frequency harmonic injection technology, designing a disturbance observer algorithm to establish a state equation set, and constructing a nominal inverter model by using a low-pass filter; the total disturbance amount is estimated in real time by comparing the difference value between the actual current output and the nominal model output, a feedback control strategy is constructed, the disturbance estimation value serves as a feedforward compensation signal to be superposed to the current controller output, and disturbance components in different frequency ranges are processed in a classified mode according to disturbance types. A disturbance observer bandwidth parameter and a filter cut-off frequency are set, a disturbance estimation value is compensated to a current control loop in real time through a feedforward compensation signal to suppress the influence of power grid disturbance on the grid-connected current, and the technical problem that it is difficult to accurately estimate and compensate the influence of power grid disturbance on the grid-connected inverter in real time is solved.

The invention discloses an impedance remodeling method for suppressing harmonic oscillation based on a superconducting magnetic energy storage system, and belongs to the technical field of power generation, power transformation or power distribution. The method comprises the following steps: analyzing theoretical characteristics of the superconducting magnetic energy storage system, analyzing mathematical models and working characteristics of an SMES and a storage battery, and carrying out theoretical modeling on the hybrid energy storage system; the method comprises the following steps: performing small signal modeling on a grid-connected converter control system under voltage control type virtual synchronous control, and establishing a grid-connected converter small signal sequence impedance model; a sequence impedance remodeling model is introduced, the influence of the sequence impedance remodeling model on the low-frequency impedance of the virtual synchronous control system is revealed, in order to obtain the optimal sequence impedance of the grid-connected converter, real-time and accurate power grid impedance information is obtained by injecting a multi-harmonic disturbance signal into the grid-connected inverter, and a traditional impedance remodeling strategy is dynamically adjusted according to the information. It is ensured that the system still has good stability margin when the power grid impedance fluctuates in a wide range, and the adaptability of the grid-connected inverter under different power grid working conditions is improved.

The invention belongs to the technical field of new energy active support stability control, and provides a fan power decoupling method based on adaptive virtual impedance and feedforward compensation. According to the method, dynamic characteristics of active power and reactive power in the system are analyzed by combining a topological structure of a doubly-fed fan grid-connected system and fan internal control, and a small signal model is constructed based on power transmission characteristics. A self-adaptive virtual impedance strategy based on power grid impedance characteristic adjustment is introduced for the problem of power coupling caused by high line impedance in a weak power grid environment and dynamic and control loop characteristics of flux linkages in a fan. Meanwhile, through a disturbance component extraction and feedforward control strategy, a disturbance signal in rotor current is introduced into a power ring for adjustment, and power decoupling control is realized. The method overcomes the limitation that an existing decoupling control technology is poor in effect, the control principle is clear, engineering implementation is easy, and the stability and the dynamic response capability of the doubly-fed fan in the weak power grid environment can be improved.

The invention discloses a variable frequency driving device energy recovery control system based on direct power supply of a high-voltage power grid, and relates to the technical field of electrical transmission and energy recovery control. Updating the power grid impedance model in real time by using a complex impedance calculation method; load operation state parameters are dynamically adjusted in combination with motor end output power, rotating speed change and torque calculation; according to the method, regenerative energy is accurately calculated, a feedback path is adjusted according to voltage fluctuation and frequency deviation of a power grid, a feedback current fluctuation ratio and a power factor are monitored, a feedback path conduction proportion is optimized in real time, when the current is unstable or the power factor is abnormal, a suboptimal path is automatically switched, and continuous and stable operation of a system is guaranteed; according to the invention, the energy feedback efficiency and the power grid compatibility of the high-voltage power grid variable-frequency driving device are effectively improved, and the method is suitable for energy feedback application of a high-power motor driving system.

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 relates to the field of power grid simulation, and particularly discloses a control method of an alternating-current power grid broadband oscillation simulation device based on a component physical model, which realizes broadband domain oscillation simulation of an alternating-current power grid based on the component physical model and a notch filter. Specifically, according to the control method of the alternating-current power grid broadband oscillation simulation device based on the element physical model, an adjustable element physical model type and a corresponding impedance parameter serve as input conditions, and a dynamic voltage compensation component excited by power grid impedance is calculated in combination with an adjustable notch filter; and a power grid simulation reference signal is constructed in real time through superposition of an original input reference voltage value and a dynamic voltage compensation component excited by power grid impedance, so that oscillation simulation in a wide frequency domain of the alternating-current power grid is realized.

The invention provides a network construction type energy storage wide short circuit ratio adaptive stability control method and system, and the method comprises the steps: carrying out the calculation based on a power grid energy storage parameter, power grid impedance and energy storage impedance, and obtaining a dynamic short circuit ratio; according to the dynamic short-circuit ratio, switching the power grid operation condition mode to a power grid operation condition mode corresponding to the dynamic short-circuit ratio; in a power grid operation working condition mode, obtaining optimized virtual inductance resistance parameters or frequency-variable admittance regulator parameters; a corresponding control instruction is generated according to the virtual inductance resistance parameters or the frequency-variable admittance regulator parameters, and self-adaptive stability control is completed; real-time identification and dynamic adjustment of the power grid impedance and the energy storage impedance are achieved, traditional fixed parameter control limitation is broken through, the dynamic short-circuit ratio is obtained through calculation, the problem of power angle instability under the wide short-circuit ratio is solved, corresponding switching of power grid operation working condition modes can be conducted based on the dynamic short-circuit ratio, differential control requirements of a weak power grid and a strong power grid are considered, and the method is suitable for large-scale popularization and application. And the full-working-condition adaptive capacity is improved.

The invention provides a grid-connected inverter impedance detection method based on an L-shaped filter, and belongs to the technical field of grid-connected inverter impedance detection. A multi-frequency-point disturbance signal is injected into a preset grid-connected inverter working point, time domain data of inverter side current and common coupling point voltage are collected, fast Fourier transform analysis is carried out on the collected data, amplitude and phase information corresponding to each injection frequency point is extracted, and a frequency domain feature vector matrix is established; and establishing a frequency compensation matrix model to compensate and correct high-frequency band measurement data based on a frequency characteristic attenuation vector, calculating to obtain optimal estimated values of power grid impedance and grid-connected inverter output impedance, performing error analysis and precision verification on an impedance detection result, and outputting a verified impedance parameter value. The technical problem of insufficient power grid impedance detection precision caused by high-frequency band attenuation of the L-shaped filter is solved.

Disclosed in the present invention are a power grid impedance measurement method and apparatus. The method comprises: generating a characteristic harmonic current instruction on the basis of a harmonic-signal generation algorithm, and inputting the characteristic harmonic current instruction into a direct-current voltage feedback control loop; receiving the characteristic harmonic current instruction to generate a control signal, and performing current tracking control to obtain a harmonic current to be injected; converting an information electronic signal of a main circuit into a driving signal in a device control loop, and selecting a preset harmonic injection mode in real time on the basis of a harmonic injection target frequency; when active harmonic injection is selected, controlling the turning-on and turning-off of a switch tube, and injecting said harmonic current into a power grid; when passive harmonic injection is selected, controlling the turning-on and turning-off of an IGBT, controlling a time and a current flow direction of when a capacitor is connected to the power grid for operation, and injecting said harmonic current into the power grid; and selecting voltage and current signals to perform signal decomposition, processing and analysis, so as to obtain a power grid impedance. By means of the present embodiment, a power grid impedance is effectively measured, the disturbance to a power grid during impedance measurement is reduced, and the measurement precision is improved.

The invention relates to the technical field of electric energy quality management of an electric power system, and discloses an industrial power grid voltage fluctuation suppression method and system, and the method comprises the steps: firstly building a system-level voltage and current forward transmission model composed of a power unit, a filter circuit and power grid impedance which are cascaded; reversely constructing a feedforward controller based on a voltage and current forward transfer model, and generating a main compensation voltage instruction according to the power grid disturbance quantity detected in real time; state parameters of each power unit are obtained, a differential equation is constructed, and a comprehensive real-time health degree index is obtained through fuzzy reasoning; dynamically correcting an equivalent impedance parameter in the forward transfer model by using the index, and calculating a voltage distribution weight of each unit; and decomposing the total compensation voltage instruction into each unit modulation signal according to the weight. Through systematic modeling, intelligent state evaluation and dynamic fault-tolerant distribution, high-speed, accurate and high-reliability suppression of the voltage fluctuation of the industrial power grid is realized.

The invention discloses a virtual power plant system integrating multiple resources and a flexible scheduling method of the virtual power plant system, and relates to the technical field of virtual power plant management. Analyzing photovoltaic fluctuation characteristics, energy storage response capability indexes and stability indexes of the load power data corresponding to various types of data, and performing normalization processing; establishing a resource interaction tensor based on the collected data, fusing the power grid frequency deviation and the line load, and constructing a collaborative optimization model containing time delay compensation; updating the power grid frequency and the line load rate with a fixed time window, dynamically solving the collaborative optimization model, and outputting a load regulation quantity and an energy storage target scheduling instruction; and obtaining the power grid impedance characteristics and load distribution parameters of the area to be loaded with the control instruction, analyzing the scene deviation degree of the area, and correcting the scheduling value based on the scene deviation degree. The scheduling precision is improved, and the complex power grid compatibility is improved.

The invention relates to the technical field of power electronic converters, and discloses a grid-connected inverter multi-parameter online setting method, system and device and a medium. The method comprises the following steps: establishing a circuit simulation model of the grid-connected inverter; output currents of the grid-connected inverter under different power grid impedance working conditions are obtained through the circuit simulation model, and target control parameters of the grid-connected inverter under different power grid impedance working conditions are obtained through iterative search by adopting a particle swarm optimization algorithm through the circuit simulation model; performing off-line training on the parameter reasoning model through the output current of the grid-connected inverter under different power grid impedance working conditions and the target control parameter under the corresponding power grid impedance working condition; acquiring an output current of the grid-connected inverter in real time, and inputting the output current acquired in real time into the trained parameter reasoning model to obtain a corresponding target control parameter; and on-line setting is performed on the control parameters of the grid-connected inverter through the target control parameters output by the parameter reasoning model, so that rapid setting can be realized.

The invention relates to the technical field of self-synchronizing voltage source control, and discloses a balance current controlled self-synchronizing voltage source control method and system. The method comprises the following steps: acquiring and preprocessing operation data of a grid-connected inverter to obtain active / reactive components of voltage and current of a filter element; generating a three-phase terminal voltage instruction of the self-synchronizing voltage source based on the components, and determining a current instruction signal in combination with the grid-connected voltage; a three-phase modulation signal is generated through adjustment of a PIR controller and coordinate inverse transformation, then a filter inductance value is calculated according to the ripple characteristic of the modulation signal and a switching period, a filter capacitance value is determined by combining resonant frequency, and finally accurate control of the self-synchronizing voltage source is realized according to a filter parameter. By dynamically calculating the matching parameters of the filter inductance and the filter capacitance, the active regulation and control capability of the output impedance characteristic of the inverter is enhanced, and the resonance risk during the impedance change of the power grid is effectively inhibited. The technical problem that the stability is limited due to insufficient impedance regulation and control in the prior art is solved.

The invention discloses an offshore wind power flexible direct current converter valve fault ride-through control method for reducing transient current overshoot, relates to the technical field of new energy grid connection, and solves the problem of transient current overshoot of an offshore wind power flexible direct current converter valve (MMC) during a fault ride-through period. A mathematical model of the offshore wind power flexible direct current converter valve is established; separating positive and negative sequence components by adopting a bisynchronous rotation dq coordinate system transformation mode, and designing a corresponding positive sequence inner ring current controller and a corresponding negative sequence inner ring current controller; detecting the power grid voltage drop condition through an effective value algorithm, adjusting active and reactive power reference values according to the detected power grid voltage value, and controlling the voltage to be stable; the method comprises the following steps: estimating the impedance of a power grid in real time by using a Kalman filter, introducing adaptive virtual impedance, dynamically adjusting a virtual impedance value through model predictive control (MPC), and adaptively inhibiting transient current; according to the method, it can be ensured that transient current overshoot is effectively reduced during the fault ride-through period of the offshore wind power flexible direct current converter valve, the stability and reliability of the system are improved, and a safer and more efficient fault ride-through control strategy is provided for offshore wind power grid connection.

The embodiment of the invention relates to a dynamic reactive power control method and device for a new energy plant station, and the method comprises the steps: calculating a dynamic safety domain of virtual impedance based on a real-time estimation value of power grid impedance; based on a multi-time scale reinforcement learning algorithm, generating a virtual impedance control quantity under the constraint of the dynamic security domain; obtaining a reactive power output error value, and correcting the virtual impedance control quantity by using the reactive power output error value; and performing reactive power output control on the inverter of the plant station based on the corrected virtual impedance control quantity. According to the technical scheme provided by the embodiment of the invention, the power grid impedance is predicted through the multi-time scale reinforcement learning algorithm, the virtual impedance control quantity is generated accordingly, the upper layer prediction model can predict the impedance change trend in advance and provide a prospective reference for lower layer dynamic correction, and the lower layer dynamic correction model can realize instantaneous disturbance suppression. And rapid fine tuning of the virtual impedance is realized, so that more accurate virtual impedance control quantity can be obtained.

The invention, which relates to the technical field of distributed power generation, discloses a modularized distributed photovoltaic inverter cluster intelligent regulation and control system comprising an impedance identification module, an impedance control module, a state sensing module, a fault diagnosis and isolation module, a power distribution module and a cluster fault control module. The power grid impedance monitoring module is used for monitoring voltage and current signals of a grid-connected point of the photovoltaic inverter, calculating a power grid equivalent impedance value, an impedance change trend and a harmonic component proportion of the current photovoltaic inverter, and generating power grid impedance information. The impedance identification module and the impedance control module are arranged, adjustment is carried out based on the virtual impedance parameters, the resonance problem caused by power grid impedance fluctuation is effectively suppressed, the situation that grid-connected current distortion affects the electric energy quality is avoided, the photovoltaic inverter cluster stably operates in a power grid impedance change scene, and the power grid impedance change efficiency is improved. And the cluster grid-connected power quality and the adaptability to the power grid environment are improved.

The invention discloses a composite impedance remolding stability improving method based on power grid voltage feedforward, and the method comprises the steps: connecting a low-pass filter in series in a power grid voltage proportion feedforward link, maintaining the power grid voltage feedforward low-frequency harmonic suppression capability, and improving the phase margin of the output impedance of an inverter in a middle-high frequency band at the same time. And a power grid voltage feed-forward branch for eliminating the negative damping influence of the phase-locked loop is added to a public grid-connected point, so that the stability of the grid-connected inverter is improved, the phase margin of the system is greatly improved, and the grid-connected inverter can still keep higher robust stability when the impedance of the power grid is higher. The stability of the grid-connected inverter is improved when the impedance of the power grid changes in a wide range, the quality of grid-connected current is improved, and the problem that the system is faced with instability after the influence of power grid voltage feedforward and PLL is considered under a weak power grid is effectively solved.

The invention discloses an impedance analysis method for forced subsynchronous oscillation of a doubly-fed wind power plant grid-connected system, which is used for evaluating the risk of forced subsynchronous oscillation and belongs to the technical field of doubly-fed wind power plants. The method comprises the following steps: step 1, determining an inter-harmonic frequency output by a doubly-fed fan, and judging whether forced subsynchronous oscillation of a doubly-fed wind power plant grid-connected system can be excited or not; step 2, establishing a small signal impedance model of the doubly-fed wind power plant and the power grid; step 3, calculating the amplitude ratio and phase difference of the double-fed wind power plant and the power grid impedance under the inter-harmonic frequency; step 4, calculating a proportion A (sih) of an inter-harmonic current amplitude to a fundamental current amplitude based on a system steady-state equivalent circuit; and step 5, judging the severity of the forced subsynchronous oscillation according to the calculated A (sih). The forced subsynchronous oscillation mechanism and physical significance can be clearly disclosed, and the forced subsynchronous oscillation characteristic can be comprehensively analyzed.

The embodiment of the invention discloses a junction temperature control method and device for an inverter switching device, and the method comprises the steps: determining a target reactive current for supporting the operation of a power grid according to a measured power grid impedance parameter under the condition of low voltage ride through, and determining the minimum bus voltage of an inverter under the target reactive current, and then the output reactive current of the inverter is controlled to be the target reactive current, so that stable operation of the power grid can be supported under the condition of low voltage ride through of the power grid. The bus voltage of the inverter is adjusted between the preset maximum bus voltage and the preset minimum bus voltage, the target bus voltage meeting the condition that the junction temperature of the switching device does not exceed the preset junction temperature upper limit is determined, and the junction temperature of the switching device in the inverter does not exceed the safety range by controlling the inverter to operate at the target bus voltage subsequently. And the operation safety of the system is improved.

The invention discloses a mode switching method, device and equipment of an energy storage converter and a storage medium, and relates to the technical field of power grid control, and the method comprises the steps: obtaining a multi-mode control grid-connected model of the energy storage converter, and the grid-connected model comprises a grid-following type control model and a grid-constructing type control model; based on the grid-connected model, injecting a high-frequency small signal into a power grid through an energy storage converter, and processing the high-frequency small signal by adopting a discrete Fourier transform algorithm to obtain grid-connected point voltage and current response; obtaining a power grid impedance parameter according to the grid-connected point voltage and current response; calculating an operation short-circuit ratio according to the power grid impedance parameter in combination with the actual output power of the energy storage converter and the power grid voltage amplitude; according to the operation short-circuit ratio and the short-circuit ratio threshold value, mode switching is carried out on the following network type control and the construction network type control, and the method can improve the accuracy of mode switching of the energy storage converter.

The invention discloses a multi-station grid-connected configuration method and system mixed with a grid-forming inverter, and belongs to the technical field of power grid electric energy quality control. According to the configuration method, node mutual impedance is decoupled through capacity information of each region node, so that an equivalent power grid impedance model of each region is established, and the system is simplified to solve the problem of key region node stability. Secondly, describing a quantitative relation among equivalent power grid impedance, the capacity and the position of the network construction type converter and the stability margin of the system by using a D segmentation method, and accurately designing a configuration scheme of the network construction type converter under the requirement of determining the stability margin; according to the method, the curse of dimensionality of a multi-station system is broken through, a quantitative basis is provided for the minimum necessary capacity and the optimal position configuration of the network construction type converter under the constraint of the specific stability margin, and the stability of the new energy multi-station grid-connected system under the weak power grid condition is effectively improved.

The present invention provides a grid simulator and a test device for the stability test of a grid-connected converter. Among them: The voltage-controlled converter uses a virtual impedance controller and a voltage controller to achieve the port voltage characteristics of the simulated grid, and the voltage-controlled converter has a relatively high switching frequency; the current-controlled converter uses a transient current controller and a current controller to absorb or generate the port load current of the simulated grid, and the current-controlled converter has a relatively low switching frequency; the AC sides of the two converters are connected in parallel and directly connected to the port of the simulated grid, or connected to the port of the simulated grid through a resistor-impedance network. The virtual impedance controller eliminates the differential operator through the Norton equivalent circuit and accurately reproduces the port impedance characteristics of the grid. The present invention can effectively simulate and shape the grid impedance characteristics in a wide frequency band, so as to conveniently realize the stability test of the grid-connected inverter under different grid impedance conditions.