12results about How to "Improve transient stability" patented technology

This invention discloses a virtual synchronous low-voltage ride-through control method and system for wind turbines with energy storage coordination. The method includes: real-time acquisition of operating parameters of the wind turbine grid connection point and the energy storage system; determining low-voltage faults based on the effective voltage value of the grid connection point and calculating the voltage drop depth; adaptively updating the virtual inertia and damping coefficient based on the drop depth, and calculating the stator transient flux linkage to generate rotor compensation voltage to suppress overcurrent and electromagnetic torque impact; and performing differential correction based on the updated inertia and damping during the fault recovery phase to suppress active power and frequency oscillations, while simultaneously controlling the energy storage system to output reactive power support and active power support based on voltage and frequency deviations. The energy storage system is a hybrid energy storage system composed of lithium batteries and supercapacitors. This invention adopts a unified virtual synchronous generator control structure, eliminating the need for control mode switching and additional hardware, and effectively suppressing rotor overcurrent and low-frequency oscillations.

The application belongs to the technical field of VSG control, and specifically discloses a self-adaptive virtual resistance control method and system based on power feedback switching, which comprises the following steps: monitoring the state of an electric network in real time, and judging the running state of a control system of a virtual synchronous generator; according to the running state of the control system of the virtual synchronous generator, switching actual active power or virtual active power at a grid-connected point of the virtual synchronous generator as a feedback quantity of an active power control loop of the control system of the virtual synchronous generator, so that the mathematical effect of the virtual resistance in a transient process is equivalent to the effect of a real grid line resistance, and self-adaptive virtual resistance control is completed. The application solves the conflict problem between small signal stability improvement and transient stability deterioration caused by the virtual resistance.

The invention discloses an energy consumption device control method and system suitable for symmetric monopole-bipolar direct current, which are applied to the technical field of direct current control, and the method comprises the steps: obtaining the electrical quantity data of a target direct current system; performing abrupt change analysis on the electrical quantity data, and determining a fault event signal based on an obtained analysis result; based on the fault event signal, determining an energy consumption branch input by the target direct current system; a corresponding energy consumption branch is reconstructed, a reconstruction result is executed, and the voltage of the direct-current bus, the current of the sound pole converter and the temperature of the energy consumption resistor are obtained; processing by utilizing a multivariable decoupling control technology to obtain energy consumption power difference data; and based on the energy consumption power difference data, a cooperative control strategy is generated by adjusting an offshore wind plant in the target direct current system. According to the method provided by the invention, the technical problem that the transient stability of the system is influenced due to control target conflict caused by the fact that the independent action of the traditional energy consumption device is not deeply coordinated with other control structures of the direct current system can be solved.

The application discloses a novel three-stage operational amplifier indirect frequency compensation circuit and belongs to the electronic circuit field. A , a second resistor R B , a first capacitor C C1 , a second capacitor C C2 , NMOS tubes MN1-MN8 and PMOS tubes MP1-PMOS tubes MP6; the NMOS tubes MN1-MN5 and the PMOS tubes MP1-PMOS tubes MP2 are a first gain stage of an operational amplifier; the NMOS tubes MN6-MN7 and the PMOS tubes MP3-PMOS tubes MP5 are a second gain stage of the operational amplifier; the NMOS tube MN8 and the PMOS tube MP6 are a third gain stage; the second resistor R B and the first capacitor C C1 , the first resistor R A and the second capacitor C C2 are an indirect frequency compensation network. The application can greatly improve the loop phase margin and the circuit transient stability under the condition of using a smaller compensation capacitor by generating a zero point located in the left half plane to offset a sub-pole in the operational amplifier loop.

This invention relates to the field of grid converter control technology, and more particularly to an adaptive hybrid synchronization control method for a grid converter, comprising an active power outer loop controller, a hybrid synchronization control link, and an adaptive link; the system control angular frequency in the active power outer loop controller serves as the system control angular frequency input to the adaptive link; the adaptive angular frequency adjustment output by the hybrid synchronization control link is connected to the active power outer loop angular frequency of the active power outer loop controller; and the adaptive link outputs the hybrid synchronization adaptive gain of the hybrid synchronization control link. This invention can adaptively adjust the equivalent damping of the system according to the system state, ensuring a sufficiently fast power step response during normal system operation, and providing sufficient equivalent damping to ensure transient stability when the system enters a fault state.

The application discloses a kind of based on network type VSC current limiting strategy's transient stability control and analysis method, its steps include:1, in voltage control loop using anti-integrator saturation module;2, introduce current saturation angle and determine its optimum value;3, based on the introduction current saturation angle to improve VSC current limiting module;4, based on current limiting module and current saturation angle, using phase diagram to analyze system transient stability.The application introduces current saturation angle to carry out transient stability control, can effectively promote the transient stability of the system formed by network type VSC and infinite grid, and the transient stability of network type VSC is qualitatively analyzed by phase diagram.

This invention discloses a transient stability control method for a doubly-fed induction generator (DFIG) wind turbine grid-connected system under asymmetrical grid faults. By calculating the positive and negative sequence active and reactive currents output by the DFIG wind turbine grid-connected system during asymmetrical grid faults, and optimizing these outputs, transient stability control of the DFIG wind turbine grid-connected system under asymmetrical grid faults is achieved. This method considers the requirements of grid guidelines and, without adding hardware, ensures that the stable equilibrium point of the system's positive and negative sequence equivalent power angles coincides with the initial operating point during the quasi-steady state. This minimizes the unbalanced transient energy accumulated by the system during the quasi-steady state and reduces the probability of transient instability.

The invention relates to the technical field of new energy power generation of power distribution systems in mountainous areas, and discloses a stability control method, system, equipment and medium for a grid-forming type brushless doubly-fed fan, and the method comprises the steps: firstly constructing a BDFIG mathematical model, deducing an active power expression under a fault condition, and determining the quantitative relation between the power grid voltage fault depth and the system stability; secondly, an LESO improvement strategy is introduced into a virtual synchronous control (VSynC) loop, power angle oscillation disturbance is observed and compensated in real time, and the transient stability of the BDFIG grid-connected system is remarkably improved.

The invention discloses a power system transient stability control method and device based on active low voltage ride through of a wind turbine generator. According to the method, a near-end strategy optimization algorithm is taken as a core, and a reinforcement learning model is constructed: a fan grid-connected power system is taken as an environment, and multi-moment characteristic electrical quantities of a node model of the fan grid-connected power system are extracted to construct an observation state; and the end time of the active low-voltage ride-through is used as a control action. And through training and network learning of a near-end strategy optimization algorithm, the optimal low-voltage crossing end time is decided, and an optimal control strategy enabling the transient state of the system to be quickly recovered to be safe is generated. According to the method, transient stability control measures can be quickly and accurately given when the system is disturbed.

The application provides a kind of based on multistage conversion vehicle-mounted direct-current power supply voltage stabilizing control method and system, it is related to power supply voltage stabilizing control technical field, by extracting the disturbance characteristic quantity of the input side voltage of former stage converter;Further determine the feedforward compensation of the voltage outer ring of latter stage converter;According to the feedforward compensation and the reference instruction of the voltage outer ring of latter stage converter, determine the voltage stabilizing control instruction of latter stage converter;The starting time of the carrier cycle of former stage converter is synchronized with the starting time of the carrier cycle of latter stage converter, and the cooperative switching period of the carrier synchronization signal shared by former stage converter and latter stage converter is obtained;In the cooperative switching period, the duty cycle of latter stage converter switch tube is updated, and the real-time voltage of intermediate direct-current bus in voltage stabilizing tracking state is fed back to the control loop of former stage converter.The application can realize the synchronous voltage stabilizing regulation of multistage direct-current conversion circuit under dynamic working condition, so as to improve the transient stability of vehicle-mounted direct-current bus.

The invention discloses a flexible power recovery control method and device for a grid-forming inverter and a storage medium, and belongs to the technical field of photovoltaic new energy grid connection. The method comprises the steps that an active power dispatching instruction and current operation parameters of the inverter are acquired; determining a transient stability power boundary constraint condition of the current operation point based on the parameters; according to the instruction and the boundary condition, calculating the minimum adjustment step length required for meeting transient stability; comparing the minimum step length number with a preset expected step length number, and adaptively selecting one of two control modes of variable-step-length step climbing or inertial link equivalent recovery according to a comparison result; shaping the scheduling instruction according to the selected mode, and generating a smooth active power reference signal; and finally, inputting the signal into a droop control loop to realize stable control of power output of the inverter. According to the invention, the problems of long transient transition time, large output waveform overshoot, transient instability and the like of the grid-forming inverter under high-power scheduling are solved.

The application discloses an emergency control strategy optimization method in a switch refusal operation scene, determines an emergency control trigger criterion in a switch refusal operation scene after a fault, and divides the scene into two categories of system stability before switch refusal and system instability before switch refusal; the emergency control best action time is determined according to the direction of electromagnetic power mutation of an equivalent single-machine system caused by the emergency control; and the emergency control measure quantity is determined through time domain simulation at the emergency control best action time. The application analyzes the influence law of the emergency control action on transient stability in different switch refusal scenes, optimizes the emergency control action time and the emergency control quantity, improves the effect of the emergency control when the equipment protection switch refuses to operate, reduces the control strength, reduces the equipment risk and the system risk, and improves the system transient stability.