29 results about "Rotor side converter" patented technology

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

The invention discloses a multi-frequency subsynchronous oscillation self-adaptive suppression method for a doubly-fed wind power generation system, and belongs to the technical field of power system stability control. The invention aims to solve the problem that an existing method only suppresses single oscillation frequency and cannot guarantee stable operation of a wind turbine generator and a power grid. Comprising the steps that discrete current signals of the double-fed wind power generation system are collected, a sparse Fourier observer is used for sequentially conducting frequency spectrum rearrangement, window function filtering, frequency domain down-sampling and fast Fourier transformation, positioning circulation and valuation circulation on the discrete current signals, and the frequency and amplitude of subsynchronous oscillation components of the double-fed wind power generation system are obtained; a parallel multi-frequency self-adaptive wave trap is connected into a rotor side converter control loop of the doubly-fed wind power generation system, parameters of the wave trap are dynamically adjusted, and a suppression signal opposite to a subsynchronous oscillation component is output to filter out the subsynchronous oscillation component. According to the invention, the subsynchronous oscillation of the power system can be effectively suppressed under the condition of high-proportion new energy access.

The invention discloses a new energy positive and negative sequence voltage coordinated optimization method adaptive to high-power fault impact, which comprises the following steps of: constructing an optimal unbalanced voltage suppression model of a doubly-fed wind turbine generator under an asymmetric fault of a power grid, and taking the minimum voltage unbalance degree of a grid-connected point as a target function by the model to suppress the optimal unbalanced voltage of the doubly-fed wind turbine generator under the asymmetric fault of the power grid; the capacity constraint of the rotor side converter and the synchronous stability constraint of the system are included; based on the optimal unbalanced voltage suppression model, reconstructing a double-sequence synchronous rotating coordinate system; carrying out convexity processing on the reconstructed model, relaxing the capacity constraint of the rotor-side converter into a second-order cone form, and introducing an auxiliary variable to convert a target function and related constraints into a standard second-order cone programming problem; and solving the second-order cone programming problem, obtaining an optimal voltage dynamic control instruction, and controlling the new energy generator set. According to the method, the inter-sequence coupling effect can be accurately considered, so that the optimal suppression of the voltage imbalance is realized on the premise of ensuring the safety and stability of a machine-network system.

The invention relates to the technical field of offshore wind power inertia control, in particular to an offshore wind power inertia supporting method considering frequency deviation. According to the method, virtual inertia control is added to offshore wind turbine generator rotor side converter control, and rotation kinetic energy stored in a fan is temporarily released to compensate for active power loss of a system; according to the method, a self-defined virtual inertia coefficient is calculated by considering the participation of a fan in inertia support potential, rapid system inertia support is actively provided, active inertia support control of an offshore wind plant is realized under different operation conditions, and the virtual inertia coefficient is fully amplified under high-frequency deviation to make up for active power loss and suppress frequency fluctuation; under the low frequency deviation, the virtual inertia coefficient is appropriately amplified to compensate the active power vacancy of the system, and the problem of system frequency instability is avoided at the same time.

This application belongs to the field of new energy technology, specifically disclosing a multi-objective cooperative transient control method for an energy storage-type AC excitation synchronous condenser. It includes: determining the fault stage of the energy storage-type AC excitation synchronous condenser in real time based on real-time operating parameters, and dynamically determining the control objective; considering the controllability constraints of the rotor-side converter output voltage, rotor current safety constraints, and flux linkage stability decay constraints, calculating the port positive-sequence inductance value, negative-sequence inductance value, and transient inductance value corresponding to the control objective at the current stage; and substituting the obtained port positive-sequence inductance value, negative-sequence inductance value, and transient inductance value into the solution to obtain the corresponding current command value. This application fully considers the different transient characteristics at different stages of fault development and sets differentiated optimization objectives to achieve multi-objective cooperative control throughout the fault process; it introduces the port three-sequence inductance as a decision variable, and by dynamically adjusting the inductance value, achieves multi-objective cooperative fault ride-through throughout the entire process of the AC excitation synchronous condenser.

The application discloses a method for suppressing subsynchronous resonance of a doubly-fed wind turbine based on additional electromagnetic torque, and the method comprises the following steps: constructing a transfer function between a rotor-side electromagnetic torque variation and a rotor speed disturbance by a flux linkage equation of a three-phase asynchronous motor and a rotor-side electromagnetic torque expression of the three-phase asynchronous motor; deriving a generation mechanism of the subsynchronous resonance from a physical layer according to the transfer function; and adding a subsynchronous resonance damping control strategy for additional electromagnetic torque of a target doubly-fed wind turbine in a d-axis controller of a rotor-side converter according to the generation mechanism of the subsynchronous resonance, so that the target doubly-fed wind turbine generates an electromagnetic torque which is opposite in phase to the rotor speed disturbance, thereby effectively suppressing the subsynchronous resonance of a power transmission system for transmitting wind power from the doubly-fed wind turbine to outside through a series compensation transmission line.

The application provides a high-inertia double-fed motor unit and a control method thereof. The corresponding control method comprises the following steps: when an alternating current system in which the high-inertia double-fed motor unit is located is in a normal operation state, determining a first active instruction value of a rotor side converter according to a pre-set rotating speed instruction value of a double-fed motor; when the alternating current system is in a fault operation state, determining a second active instruction value of the rotor side converter according to a rated power of the double-fed motor; when the alternating current system is switched from the fault operation state to the normal operation state, determining a third active instruction value of the rotor side converter according to a current rotating speed of the rotor of the double-fed motor. The application relies on the double-fed motor with a high rotating inertia rotor to reserve high rotor kinetic energy, and provides active frequency support for the system by releasing the rotor kinetic energy when the system fails.

The application discloses a power coordination recovery control method for inhibiting repeated low voltage ride through of a doubly-fed wind turbine. The application proposes to coordinate the recovery slope of active current and reactive current aiming at the repeated low voltage ride through problem of the doubly-fed wind turbine after fault clearance. Firstly, a phase-locked loop second-order underdamped model is established to estimate the peak time and valley time in the voltage recovery process; then, the current recovery expression is substituted into the grid connection point voltage equation to construct a voltage constraint inequality, so that the peak time does not trigger high voltage ride through and the valley time does not trigger low voltage ride through; finally, the feasible range of the active recovery slope and the reactive recovery slope is determined according to the constraint inequality, the optimal active and reactive current recovery slope is determined by combining the current limiting or recovery time matching constraint, and the current reference instruction is input to the rotor side converter. The application can effectively inhibit voltage oscillation when exiting the low voltage ride through stage and improve the transient stable operation ability of the wind turbine under weak grid conditions.

The invention discloses a method, a system, equipment and a medium for adaptively improving an inertial response effect and frequency damping based on a phase-locked error, and relates to the technical field of power grid inertial response, and the method comprises the following steps: representing the phase-locked error through a q-axis voltage component obtained through coordinate transformation of a grid-connected point three-phase voltage signal; inputting the q-axis voltage component into an inertia control link to obtain an additional torque or active power instruction value; adaptively adjusting the damping coefficient T based on the absolute value of the q-axis voltage component; superposing the additional torque or active power instruction value with active power or torque instruction values generated in other links to obtain a target instruction value at the next moment; and d-axis and q-axis components of the excitation voltage are calculated through a proportional-integral controller, and a control signal of the rotor-side converter is generated through inverse coordinate transformation. A q-axis component in three-phase voltage of a grid-connected point is extracted to accurately represent a phase locking error, and in combination with adaptive damping adjustment, rapid identification and active response to power grid frequency disturbance are realized.

The invention discloses a doubly-fed wind power converter and a control method thereof. The control method comprises the following steps: acquiring current of a grid-connected point and rotor current of a rotor side; calculating a deviation current between the current of the grid-connected point and the rotor current, and introducing the deviation current as a feedforward quantity into a current loop of a rotor-side converter; and generating a control signal for the rotor-side converter based on the given current output by the power loop and the feed-forward quantity. According to the invention, the dependence on motor parameters is effectively reduced, and the control precision and the parameter error-tolerant rate of the excitation current are improved.

This invention presents a crowbar reversal strategy based on rotor fault current and grid voltage. This method is an improved crowbar protection strategy, adding a series protection resistor between the original crowbar circuit and the rotor-side converter. It employs a fast switching criterion based on grid connection point voltage vector drop detection, which can simultaneously limit the current surge flowing through the RSC and the rotor windings. For different fault clearing times, a crowbar reversal strategy based on rotor fault current and grid voltage is designed, which can reduce the crowbar activation time to a certain extent, thereby reducing the absorbed reactive power, and also offers greater flexibility.

The invention relates to the technical field of pumped storage, and particularly discloses a double-fed pumped storage low-voltage ride-through method based on a dynamic demagnetization coefficient, and the method comprises the following steps: detecting whether a power grid has a low-voltage fault or not; when a low-voltage fault is detected, determining a demagnetization coefficient initial value according to a stator flux linkage transient component; based on the attenuation characteristic of the transient component of the stator flux linkage, a demagnetization coefficient dynamically changing along with time is calculated; generating a rotor current reference value according to the dynamic demagnetization coefficient; according to the method, the dynamic distribution strategy of the capacity of the rotor side converter during the fault period is optimized, the demagnetization coefficient is calculated and adjusted in real time based on the transient component of the stator flux linkage through dynamic demagnetization coefficient control, the generated dynamic demagnetization current can effectively inhibit the overcurrent and overvoltage of the rotor, and the over-current and over-voltage of the rotor can be effectively inhibited along with the attenuation of the transient component. And the capacity is gradually released to provide timely reactive power support for the power grid, so that the safety of the converter is protected, and the power grid voltage recovery is assisted.

The invention discloses a staged grouping method and system for a whole wind power plant fault process and electronic equipment, and the method comprises the steps: carrying out the grouping equivalence of a whole wind power plant group based on a slip ratio and an rsc inner ring proportionality coefficient of a rotor-side converter in an unreacted stage of a converter; when at least one fan action enters a crowbar protection Crowbar input-asynchronous machine stage, performing initial classification on a whole fan group based on whether the fan action exists, and performing grouping equivalence based on a slip ratio and an inner ring proportionality coefficient of a rotor side converter on the basis of an initial classification result; and when the Crowbar exits and all the fans return to the rsc control stage, keeping the grouping result until the fault is removed. According to the method, the wind power plant short-circuit current dynamic characteristics in the whole fault process can be accurately described, accurate calculation of the wind power plant short-circuit current is achieved, and technical support is provided for high-proportion new energy power system short-circuit calculation and wind power plant equivalent grouping.

The present application belongs to the technical field of power system oscillation suppression, and specifically discloses an oscillation suppression method and system based on high-inertia energy storage type phase modifier impedance remodeling, which comprises the following steps: identifying a target suppression frequency band; obtaining the active power signal of a grid-connected new energy unit or new energy station, and performing band-pass filtering to obtain the subsynchronous and / or supersynchronous oscillation component of the target suppression frequency band; performing asymmetric complex number lead correction on the oscillation component; after amplitude shaping and safety limiting of the phase-compensated signal, the signal is injected into the rotor-side converter power outer ring of the high-inertia energy storage type phase modifier as an additional control signal to form an additional power deviation; the deviation is output as a rotor-side current reference value after PI regulation, and then a damping power opposite to the oscillation component is formed on the stator side to remodel the equivalent output impedance of the point of common coupling. The present application can suppress the subsynchronous and / or supersynchronous oscillation of the new energy station.

The application discloses a two-stage frequency modulation method, device, equipment and medium of a variable-speed pumped storage unit, and belongs to the field of power system operation control, and comprises the following steps: dividing a primary frequency modulation process of the unit into first-stage frequency modulation control and second-stage frequency modulation control; when the frequency of a power system deviates and triggers a primary frequency modulation response of the unit, the first-stage frequency modulation control is performed; the electromagnetic torque is adjusted under operation constraints through coordinated control of a rotor-side converter and guide vanes; the switching condition is determined according to the frequency variation characteristics of the system, and the first-stage frequency modulation control is switched to the second-stage frequency modulation control; the frequency support of the unit to the power system is maintained, the rotor speed is adjusted, and the rotor speed is restored to the rated speed or a stable operation interval. The application can coordinate the improvement of the frequency regulation performance of the power system and the operation safety of the variable-speed pumped storage unit without relying on additional energy storage devices, and is suitable for a power system with a high proportion of new energy access.

This invention relates to an active crowbar circuit control system and method for variable-speed pumped-storage hydroelectric power generation units, belonging to the field of variable-speed pumped-storage power generation-motor control technology. To improve the unit's low-voltage ride-through capability and enhance grid power quality, the present invention uses an RL filter circuit with a resistor connected to the crowbar-side converter and an inductor connected in parallel between the doubly-fed induction generator (DFIG) and the rotor-side converter. One end of the three-phase current detection module is connected to the CSC controller, and the other end is connected to the inductor. One end of the drive circuit is connected to the CSC controller, and the other end is connected to the crowbar-side converter. One end of the DC voltage detection module is connected to the CSC controller, and the other end is connected to a capacitor. One end of the three-phase voltage detection module is connected to the CSC controller, and the other end is connected to the three-phase power grid. This invention improves the unit's low-voltage ride-through capability.

The invention relates to a double-fed wind power plant equivalent modeling method considering low voltage ride through power characteristics, and belongs to the technical field of power system research. The method comprises the following steps: calculating the output power of a DFIG unit under LVRT, and obtaining a corresponding relation between a rotor current d / q axis component reference value and steady-state reactive power and active power during LVRT based on a voltage and flux linkage equation under a synchronous rotation coordinate and a wind power grid-connected dynamic reactive current; establishing a two-stage cluster division method based on the corresponding relationship to obtain a cluster division result; modeling a wind turbine, a fan transmission system and a stator and rotor side converter, and carrying out doubly-fed wind power plant parameter equivalence; and introducing an improved COA algorithm to identify control parameters of the doubly-fed wind power plant, determining to-be-identified parameters and an objective function, and optimizing and solving the parameters when the objective function is minimum, thereby completing equivalent modeling of the doubly-fed wind power plant. The objective of the invention is to solve the technical problems of power characteristic difference of a doubly-fed unit under a non-serious fault and difficult identification of parameters of a doubly-fed wind power plant.

The invention discloses a two-stage frequency modulation method, device and equipment for a variable-speed pumped storage unit and a medium, and belongs to the field of power system operation control, and the method comprises the steps: dividing the primary frequency modulation process of the unit into first-stage frequency modulation control and second-stage frequency modulation control, and when the frequency of a power system shifts and triggers the primary frequency modulation response of the unit, controlling the first-stage frequency modulation control and the second-stage frequency modulation control; performing first-stage frequency modulation control; the electromagnetic torque is adjusted under operation constraint through cooperative control of a rotor-side converter and a guide vane; determining a switching condition according to a system frequency change characteristic, and switching from the first-stage frequency modulation control to a second-stage frequency modulation control; and keeping the frequency support of the unit to the power system, and adjusting the rotating speed of the rotor until the rotating speed of the rotor recovers to the rated rotating speed or the stable operation interval. The frequency regulation performance of the power system and the operation safety of the variable-speed pumped storage unit can be cooperatively improved under the condition of not depending on an additional energy storage device, and the method is suitable for the power system with high-proportion new energy access.

The present application belongs to the field of wind power generation technology, aiming at the problem of voltage instability of wind farm grid-connected point caused by wind power uncertainty and grid-connected fault, a reactive power distribution strategy based on sample entropy improved symplectic geometry modal decomposition is proposed. The strategy first decomposes the total reference reactive power of the grid-connected point through symplectic geometry modal decomposition to obtain symplectic geometry components, calculates the sample entropy and similarity threshold of each component, and reconstructs the high, medium and low frequency components. Then, according to the difference in response time of the rotor side converter of the doubly-fed wind power plant and the static synchronous compensator, combined with the coordination of the shunt capacitor, the reference power of the three is distributed according to the frequency band, and the reactive power fluctuation is coordinated and suppressed. Simulation verification shows that this method avoids the defects of traditional algorithms, maintains voltage stability while greatly reducing the configuration capacity of reactive power compensation devices, and has effectiveness and economy.

According to the double-fed cluster wind power plant coordination control method and system provided by the invention, the simulation system comprising the equivalent wind power plant model and the chained static var generator model is established, the voltage amplitude of the grid-connected point is detected in real time, and corresponding control strategies are intelligently selected according to different interval ranges of the voltage amplitude, so that the coordination control of the double-fed cluster wind power plant is realized. Dynamically coordinating reactive power output of a rotor side converter, a stator side converter and a chain type static var generator of the doubly-fed wind generator; according to the method, accurate reactive power support under different voltage working conditions is realized, voltage stability of a grid-connected point is maintained in a normal voltage range, fault ride-through is rapidly completed when the voltage is abnormal, frequency support is provided through active-frequency cooperative control, and safe and stable operation of the system is ensured by adopting dynamic amplitude limiting protection and an optimization recovery strategy. And finally, the operation reliability and the power grid adaptive capacity of the doubly-fed cluster wind power plant under the power grid fault condition are remarkably improved.

The invention discloses a wind storage joint black-start method and system fusing coupling terms and improved virtual synchronization, and belongs to the technical field of black-start power supply control. A control signal is determined by introducing a V / F control strategy of a coupling term and is output to a battery energy storage unit, and the battery energy storage unit is used for providing excitation for the doubly-fed asynchronous wind generating set to realize self-starting of the doubly-fed asynchronous wind generating set; an improved virtual synchronous control strategy is adopted to control a rotor side converter, the doubly-fed asynchronous wind generating set is connected into a power grid, and the doubly-fed asynchronous wind generating set which is successfully connected with the power grid is utilized to start remaining wind power plant units; and switching the V / F control strategy introduced with the coupling item into the P / Q control strategy introduced with the coupling item, and starting the thermal power generating unit. Through coupling item control, cooperation and flexible switching of a virtual synchronization strategy are improved, wind storage combined black start is efficiently achieved, stable grid connection and efficient power grid recovery are guaranteed, and the method adapts to a new energy scene.

This invention discloses a control method for maximizing the voltage support capability of a doubly-fed induction generator (DFIG) wind turbine considering rotor-side constraints. First, an analytical model of the system's dual-sequence voltage and current, incorporating the stator inductance and magnetizing inductance of the DFIG, is established. Then, under the premise of strictly satisfying the overcurrent and overvoltage constraints of the rotor-side converter, the optimal positive-sequence and negative-sequence rotor current injection angles are analytically derived with the goal of maximizing positive-sequence voltage support and maximizing negative-sequence voltage suppression. The key innovation of this invention lies in revealing that the optimal injection angle depends not only on the grid impedance parameters but also significantly on the inherent inductance parameters of the DFIG. Simulation results show that the current command generated using this method can significantly improve the positive-sequence voltage at the point of common coupling during faults and reduce the negative-sequence voltage, thereby reducing voltage imbalance and achieving effective grid support.

The invention discloses a virtual inertia control method for a doubly-fed wind generating set and related equipment. The method comprises the following steps: acquiring a frequency deviation and a frequency change rate of the doubly-fed wind generating set; inputting the frequency deviation and the frequency change rate into a variable coefficient Bang-bang controller, and performing variable coefficient control to obtain a self-adaptive virtual inertia coefficient; calculating virtual inertia power based on the adaptive virtual inertia coefficient and the frequency change rate; calculating droop power according to the frequency deviation and the droop coefficient; superposing the virtual inertia power, the droop power and the maximum power tracking reference value to obtain an active power instruction; and transmitting the active power instruction to a rotor side converter of the doubly-fed wind generating set, thereby realizing virtual inertia and primary frequency modulation support of a power grid. According to the method, dynamic self-adaptive virtual inertia support can be realized, and the frequency stability level of a power system under high wind power permeability is improved.

The application provides a doubly-fed droop network type wind turbine control method, device and storage medium, wherein in active power control of a rotor side converter of a doubly-fed network type wind turbine, droop control is added on one hand, cooperative work of multiple wind turbines is realized, power stability of the whole wind farm is improved, and technical support is provided for large-scale wind power grid connection; on the other hand, a variable that can directly control the participation degree of inertia response of the unit, namely an inertia response participation coefficient, is introduced, a self-synchronous real-time stability control algorithm is designed, a power grid frequency change trend is predicted, the inertia response participation coefficient is dynamically modified according to the frequency prediction result, and self-regulation and self-stabilization of the inertia response are realized. Therefore, in the case of large range frequency fluctuation, the stability of the wind turbine is expected in advance, the inertia response participation coefficient is dynamically modified, and the operation stability in the case of large power grid frequency disturbance is improved.

The invention relates to the technical field of wind power grid-connected operation and control, and discloses a rotor overcurrent suppression method and system of a doubly-fed induction generator. The method comprises the following steps: obtaining a rotor current of a doubly-fed induction generator DFIG; separating the rotor current into a fundamental frequency direct current component and an alternating current free component; inputting the fundamental frequency direct current component into a proportional integral (PI) controller, and performing decoupling control of active power and reactive power; inputting the alternating current free component to a vector proportional integral (VPI) controller when detecting that the voltage of the power grid drops, so as to suppress the alternating current free component; and superposing the output of the PI controller and the output of the VPI controller to generate a control signal of a rotor-side converter RSC, and driving the rotor-side converter to realize the suppression of the rotor overcurrent. According to the application, additional hardware devices such as a Crowbar circuit do not need to be added, and the system cost is reduced.

The invention discloses a low-voltage ride-through control method for a wind turbine generator, relates to the technical field of wind power generation, and solves the problem that for a mainstream doubly-fed induction wind turbine generator, huge transient overcurrent can be induced on the rotor side of the mainstream doubly-fed induction wind turbine generator by power grid voltage drop, and the safety of a converter on the rotor side is threatened. According to the technical scheme, a hybrid energy storage system composed of a super capacitor and a storage battery is connected to a direct-current bus of a wind turbine generator converter in parallel, and an intelligent cooperative control mechanism linked with the hybrid energy storage system is designed. The method comprises the steps of generating a total power absorption instruction of the hybrid energy storage system according to a deviation and a change rate of a direct-current bus voltage when detecting that a power grid voltage drops; the method has the advantages that it can be ensured that the grid-side converter continuously provides reactive power support for the power grid during the fault period, the defect that a traditional crowbar circuit absorbs reactive power is fundamentally overcome, meanwhile, rapidness, smoothness and high reliability of the low-voltage ride-through process are achieved, and the grid connection performance of a wind turbine generator is remarkably improved.

The invention discloses a flux linkage suppression-based low-voltage ride-through control method, device and system for a grid-forming doubly-fed motor, and a storage medium, and belongs to the technical field of power generation, power transformation or power distribution. The method comprises the following steps: firstly, locking a network construction control unit and obtaining an internal potential phase based on a virtual synchronous machine principle when a voltage drop occurs in a power grid; the proportionality coefficient of the excitation flux linkage ring is dynamically adjusted, so that the system damping is maximized, and the attenuation of the transient component of the stator flux linkage is accelerated; on the basis, a rotor current instruction is generated in real time according to voltage and current capacity limitation of a rotor-side converter, and a modulation signal is output to drive the converter in combination with a feed-forward compensation strategy and a resonance controller. According to the method, rotor overcurrent and overvoltage during a fault period can be effectively suppressed without adding any hardware circuit, the attenuation speed of a transient flux linkage is remarkably improved, meanwhile, the reactive power supporting capacity of a unit to a power grid is enhanced, and high-performance low-voltage ride-through of the grid-forming type doubly-fed motor is achieved.