415 results about "Virtual inertia" patented technology

The invention discloses an optimal virtual inertia control method based on a virtual synchronous generator in the distributed power generation control field. According to the method, a control strategy of a virtual synchronous generator is employed for a micro-grid inverter to organically combine three control degrees of freedom including a droop coefficient m, a virtual inertia J and a virtual damping D, and thus optimization of key parameters of the virtual synchronous generator is achieved. Through adoption of the method, the inertia advantage of a conventional synchronous generator is fully exhibited, and the stability and the inherent dynamic performance of an inverter are also taken into consideration. Moreover, the output power and frequency oscillation problems brought by virtual inertia are solved while the power and the capacity configuration of an energy storage apparatus are considered.

The invention provides a method and apparatus for an energy storage system to participate in power grid frequency control. The method comprises the steps of monitoring power grid frequency and charged states of an energy storage system in real time; if a power grid frequency offset exceeds a maximum frequency deviation, determining the energy storage system to participate into power grid primary frequency modulation according to deviation directions and the charged states; when a primary frequency modulation starting condition is satisfied, calculating virtual inertia response, a primary variable sagging control power adjustment value and a primary frequency modulation active control instruction; according to the primary frequency modulation active control instruction, carrying out primary adjusting of active power output of the energy storage system; starting secondary frequency modulation after time delay to determine a secondary frequency modulation instruction; according to the virtual inertia response, the primary variable sagging control power adjustment value and the secondary frequency modulation instruction, determining a secondary frequency modulation active control instruction; and according to the secondary frequency modulation active control instruction, carrying out secondary adjusting of the active output power of the energy storage system. Through adoption of the method and apparatus of the invention, coordination and cooperation between the energy storage system and other machine sets in aspects of primary frequency modulation and secondary frequency modulation can be well solved.

The invention provides a virtual synchronous generator virtual inertia and virtual damping coefficient adaptive control method, which relates to the technical field of smart grid and intelligent algorithms. Firstly, the inverter based on the virtual synchronous generator is modeled, and the correlation between the output frequency of the inverter and the virtual inertia J and the virtual damping coefficient D is obtained. Then the fitness function of the adaptive control method of virtual inertia J and virtual damping coefficient D based on the improved particle swarm optimization algorithm isdetermined. Finally, the improved particle swarm optimization algorithm is applied to the active power. In the frequency control part, the real-time adaptive control of virtual inertia J and virtualdamping coefficient D is realized in order to minimize the frequency deviation and stabilize the system. The invention provides a virtual synchronous generator virtual inertia and virtual damping coefficient real-time adaptive control method, which fully utilizes the characteristics of the virtual inertia and introduces the virtual damping coefficient, so that the inverter is more stable and the frequency offset is smaller.

The invention relates to a virtual controller of electromechanical characteristics for a static power converter that includes a PLC (23) (power loop controller), which receives, at the input thereof, the power difference (ΔP) between the input power (P_in) (power delivered to the converter by the primary source) and the power delivered to the grid (P_elec) and is able to modify online the parameters of the virtual inertia coefficient and the damping factor as a function of the desired response and of the grid conditions for different frequency ranges.

The invention discloses a low-frequency oscillation disturbance source positioning system and a method of a double-fed fan grid-connected system belonging to the technical field of power system stability analysis. The system comprises a sequentially connected information acquisition module, an oscillation source positioning module and an oscillation source position output module. The method comprises acquiring network structure parameters of a grid-connected system of a double-fed fan with virtual inertia control, The dynamic energy model of doubly-fed wind turbine with virtual inertia controlis constructed by injecting bus voltage, generator node current and load node current into the system. The dynamic energy of the components or branches in the oscillation process is obtained, and thepositive and negative and changing trend of the dynamic energy are judged to trace the disturbance source of the low frequency oscillation. A low-frequency oscillation disturbance source position canbe accurately locate by that invention, the function of the fan related control link in the low-frequency oscillation is taken into consideration, and the possible influence on the fan disturbance source is analyze.

The invention discloses a master-slave control method for an energy storage inverter based on a virtual synchronous generator. The energy storage inverter comprises a master control inverter and a slave control inverter, wherein the master control inverter adopts a voltage source output mode based on the virtual synchronous generator to provide amplitude and frequency of network voltage, provide virtual inertia and a virtual damping ratio according to the capacity of the master control inverter, and meanwhile provide static active and passive current quotas to each inverter; the slave control inverter adopts a current source output mode based on the virtual synchronous generator to receive static active and passive current quotas issued by the master control inverter, and meanwhile provide the virtual inertia according to the capacity of the slave control inverter. According to the method, in island parallel operation, a load is non-uniform and fluidity is relatively low under various load conditions, and relatively high output voltage power quality is provided; compared with traditional master-slave control, a controller structure does not need to be changed when switching between grid connection and disconnection is performed, and the master control inverter and the slave control inverter independently provide the virtual inertia without depending on communication, so that improvement on system stability under dynamic condition is facilitated, and the reliability is relatively high.

The invention discloses a VSG based photovoltaic microgrid dynamic frequency stability control method. The method includes the following steps: constructing a VSG based photovoltaic microgrid system dynamic model; performing adaptive control on the virtual inertia torque and virtual damping factors of the system model; configurating system key parameters, and selecting the optimal value of the parameters; and determining a calculation example, and adopting a simulation tool to perform simulation analysis on the calculation example. The method can establish the dynamic relation between the virtual inertia and virtual damping of a system and the frequency change of the system through the analysis on a frequency oscillation process, so that the two can be adaptively changed according to the frequency change, and therefore, frequency oscillation can be effectively inhibited, the system can better cope with transient disturbances, and the frequency stability of the system can be provided.

The invention discloses a voltage control type virtual synchronizing method of a double-feed wind power generator set. Through simulating inertia and a frequency-modulating and voltage-modulating characteristic of a synchronizer, the set can be different from a characteristic of no electric grid frequency change response in a traditional current control type, thereby possessing capability of supporting voltage and frequency of a weak power grid based on the voltage control type through virtual inertia. The method provides and realizes a VCT-DFIC virtual synchronous control structure of which an inner ring is controlled by an improved double-feed generator stator voltage rotor current double-closed-loop structure based on adaptive stator virtual impedance and transmission line sag voltage feedforward compensation in a control manner which includes crossed control between stator voltage and rotor current and furthermore an outer ring is controlled by a virtual synchronous realizing algorithm. The method realizes output power control in VCT-DFIG grid integration operation in a weak grid condition with any actual impedance and effective decoupling, and furthermore a designed control structure realizes higher inertia and frequency supporting capability of the double-feed generator.

The invention belongs to the technical field of optical storage combined power generation system virtual inertia compensation, and relates to a virtual inertia compensation method for an optical storage combined power generation system based on active support control. The method comprises: modeling a photovoltaic power generation system, analyzing the virtual inertia of the optical storage combined power generation system, and including inertia analysis of a photovoltaic-energy storage system. The active support control strategy based on the standard three-order model of the synchronous machine is adopted for the photovoltaic power generation unit, the port characteristics of the synchronous generator are better simulated, necessary inertia and damping are provided for the system, the voltage stability support capacity and the frequency stability support capacity of the system after photovoltaic grid connection are improved, and the robustness of the system is effectively improved. According to the invention, the low-frequency oscillation suppression capability of the photovoltaic-energy storage combined system can be enhanced, the system stability is improved, and the new energy photovoltaic absorption capability of the power grid is further promoted.

The invention discloses a wind power plant virtual inertia increasing method based on wind-storage cooperative operation. Fan operation features in different wind speeds are analyzed and zoning is performed on the wind speeds. Through detecting system frequency fluctuation and digging frequency adjustment potential and energy storage power features of the fan itself, system frequency fluctuation is responded with real time control of active power of a wind storage system, so that increase of a virtual inertia of the wind power plant is realized. According to the invention, wind-storage combined system inertia can be improved effectively, and also, the combined system can be enabled to give active power response to frequency fluctuation in multiple wind conditions and problems such as secondary falling of frequency can be avoided at the same time. Therefore, system frequency stability is improved.

The invention discloses a virtual double-fed induction generator inertia control method coordinated with secondary frequency regulation, which solves the problem of cooperation between the virtual inertia control of a wind turbine generator and the secondary frequency regulation of a power system. On the basis of an original virtual inertia control module, a module which is coordinated with the secondary frequency regulation of a power system is added, so that the overall frequency regulation effect is increased. Moreover, in the added module, the rotational speed of the rotor of the wind turbine generator is considered, so that the wind turbine generator can continuously operate within a safe rotational speed range; the problem of the affection of system frequency fluctuation on the active regulation capability of the wind turbine generator is solved; because the affection of system frequency fluctuation on the active regulation capability of the wind turbine generator is great, in order to ensure that the double-fed induction generator has better frequency regulation capability, the steady-state frequency response of the wind turbine generator is optimized, and moreover, accordingly, a control strategy is designed, so that the frequency regulation effect of the wind turbine generator is increased to a certain degree.

The invention provides a method and a device for determining optional ranges of the virtual inertia and damping coefficient of a VSG (Virtual Synchronous Generator), and relates to the technical fieldof VSGs. The method comprises the following steps: acquiring relevant parameters of a VSG grid-connected system built from a VSG to an infinite grid; establishing a state equation of the VSG grid-connected system; determining a small signal equation of the VSG grid-connected system; determining a small signal space equation of the VSG grid-connected system; determining a transfer function of theVSG grid-connected system; determining a natural oscillation frequency function and a damping ratio function of the VSG grid-connected system; and determining the optional ranges of the virtual inertia and damping coefficient of the VSG according to the natural oscillation frequency function, the damping ratio function and a preset restraining condition which is relevant to the natural oscillationfrequency function and the damping ratio function. Through adoption of the method and the device, the optional ranges of the virtual inertia and damping coefficient of the VSG can be determined accurately, so that the running of the VSG is safer and more stable.

The invention discloses a low-frequency oscillation control parameter optimization method of a grid-connected double-fed fan with virtual inertia belonging to the technical field of power system stability analysis. The method is realized by a processing system comprising a sequentially connected information acquisition module, a robust random optimization parameter adjustment calculation module and a parameter adjustment result output module, comprising three steps of information acquisition, parameter adjustment calculation and output parameter adjustment result optimization, and obtaining aset of control parameter policy variables; Judging whether the doubly-fed fan is the cause of inducing low frequency oscillation can guide the optimization of control parameters. After the parameter optimization strategy is applied, the power angle response level of the fan is effectively improved, the fan no longer transmits oscillation energy to the power network, and the low-frequency oscillation of the fan-connected system is restrained.

The invention provides a control method and a device for connecting wind power to a flexible HVDC transmission system. Firstly, the actual frequency of an AC grid at a receiving end, the actual frequency of an AC bus bar at a wind farm side, the actual voltage at a DC side of a receiving end converter station are obtained, and the reference voltage at the DC side of the receiving end converter station is determined. Then, the voltage of DC line, the frequency of AC bus and the active power of wind farm are controlled separately, which has high reliability, short frequency modulation response time and good frequency modulation effect. Virtual synchronous machine droop control is adopted in the sending-end converter station, which improves the response speed of frequency regulation and shortens the time of frequency modulation. The frequency of the alternating current bus on the wind farm side is controlled by fixed frequency control or frequency conversion control, The active power of wind farm is controlled by virtual inertia, which makes the increased or decreased power released or supplemented in time when the flexible HVDC system provides frequency modulation for the receiving AC network, and reduces the risk of HVDC line voltage exceeding the limit, and greatly improves the reliability of HVDC system.

This invention discloses a controller and method to reconfigure the inertia, damping and fault ride-through capability of a virtual synchronous machine (VSM). The virtual inertia is reconfigured via adding a low-pass filter to the torque (equivalently, active power) signal of the VSM and the virtual damping is reconfigured via adding a virtual damper between the VSM voltage and the output voltage sent to the PWM conversion, instead of adjusting the inertia and the damping in the swing equation. The function of the virtual damper is to scale the existing converter-side inductance or to insert the desired inductance into the VSM, which increases the damping. Moreover, the fault ride-through capability of the VSM can be reconfigured to achieve the given fault-current level via reconfiguring the damping and the inertia properly.

The invention relates to a frequency support control method used for a doubly-fed wind generation set and based on two-stage power tracking optimization. The invention starts from optimization of frequency support dynamic characteristics of a wind generation set and provides a frequency support control method used for the wind generation set and based on two-stage variable proportion coefficient optimized power tracking. On the basis, a variable proportion coefficient control strategy in an inertial response stage is derived based on a virtual inertia time coefficient and a rotor movement equation, and for quick recovery of a maximum power tracking operation mode of the wind generation set after inertial support and avoiding secondary disturbance from being produced on system frequency adjustment in a recovery process, a variable proportion coefficient control strategy in a maximum power tracking operation mode recovery stage is designed by adopting fussy control. The frequency supportcontrol method provided by the invention has control robustness, a control structure is simple, engineering implementation is easy, and the quick recovery of the maximum power tracking operation modeof the doubly-fed wind generation set after inertial response and inertial support on a power grid frequency can be realized.

The invention discloses a method for controlling a wind turbine to participate in power grid frequency modulation based on virtual inertia and a pitch angle. The method comprises the following steps:when a frequency deviation exists between the rated power of a system power grid and the current frequency, calculating a proportionality factor of a tracking curve of the sub-optimal rotating speed-active power of the wind turbine under the control of the virtual inertia; calculating a reference power of an inverter at a rotor side under the control of the virtual inertia; calculating an introduced electromagnetic power at the rotor side inverter according to the frequency change rate, and accumulating the introduced electromagnetic power and the reference power to obtain a total electromagnetic power of the rotor side inverter; calculating the rotating speed deviation of the wind turbine, and adopting the rotating speed deviation of the wind turbine to calculate the electromagnetic powervariation of the rotor side inverter; obtaining an active power of a pitch angle mechanism according to the total electromagnetic power and the electromagnetic power variation, and calculating the pitch angle of the pitch angle mechanism by adopting the active power of the pitch angle mechanism; and controlling the wind turbine to increase captured wind energy and inject the active power into thepower grid according to the pitch angle.

The invention relates to an adaptive inertia damping comprehensive control method for a virtual synchronous generator. The frequency fluctuation cycle after the traditional virtual synchronous generator is disturbed is segmented to four intervals, and adaptive inertia damping comprehensive control based on the segmentation is realized. The virtual inertia is increased adaptively within the first interval and the third interval with frequency disturbance, and in the rest intervals, the initial virtual inertia values are kept unchanged; and the virtual damping is increased adaptively within thesecond interval and the fourth interval, and in the rest intervals, the initial virtual damping values are kept unchanged. Compared with the prior art, the method of the invention realizes interleaving control on the virtual rotating inertia and the virtual damping, the problem of frequency stability after disturbance of the virtual synchronous generator grid-connected system can be effectively improved, and the frequency adjustment time is shortened while the frequency overshoot is reduced.

The invention provides a power control method, control device, controller and system of wind generating sets. The method comprises the steps that the real-time frequency of a power grid is acquired; when fluctuation of the real-time frequency of the power grid meets the preset condition, the virtual inertia and the virtual droop control character of a wind power plant are determined; according tothe virtual inertia and the virtual droop control character, the power command value of primary frequency modulation of the wind power plant is determined; and according to the power command value ofprimary frequency modulation, power of each wind generating set in the wind power plant is synchronously adjusted. In the method, power synchronous adjustment is carried out on each wind generating set of the whole wind power plant based on the same power command value of primary frequency modulation, the wind generating sets of the wind power plant are coordinated and integrated into a whole, thewhole wind power plant shows the inertia and the droop control character similar to those of a synchronous generator outwards, and therefore disturbance of the power grid can be effectively suppressed through primary frequency modulation, and the stability of the power grid can be improved.

The invention discloses a frequency control method of an offshore wind power integration multi-terminal flexible DC transmission system. When a shore-based converter station exits, asynchronous power grid transient frequency deviation drop and wind farm additional pitch angle control are realized through reasonable configuration of the controllers of a converter station in a power grid at a receiver side and through wind farm additional virtual inertia control, and asynchronous power grid steady-state frequency deviation is eliminated eventually. Thus, the frequency characteristic of adjacent asynchronous power grids is improved, and the influence of failure of a converter station on the operation safety and stability of other shore-based asynchronous power grids is reduced. By using the method to analyze the exit of a shore-based converter station of a large-capacity offshore wind farm integration multi-terminal flexible DC transmission system, the designed frequency control strategy can improve the frequency stability of a shore-based AC system.

In order to solve a problem that power decoupling of a grid-connected inverter of existing virtual inertia control is insufficient, the invention provides a grid-connected inverter virtual inertia power decoupling control method based on a predicted common point voltage and belongs to the grid-connected inverter virtual inertia power decoupling control field in renewable energy power generation. The method comprises the following steps of step1, carrying out virtual inertia control on the grid-connected inverter and acquiring a virtual excitation electromotive force amplitude E and a rotor motion electrical angle theta of a synchronous generator; step2, making reactive power output by the grid-connected inverter be equal to a reactive power reference value and predicting a common point voltage upcc_calculate; step3, updating the E: superposing the E in the step1 and the upcc_calculate in the step2 and acquiring the updated virtual excitation electromotive force amplitude E; and step4,according to the theta in the step1 and the updated E acquired in the step3, calculating a three-phase modulated wave, and converting the three-phase modulated wave into an IGBT driving signal of a three-phase inverter bridge in the grid-connected inverter so as to realize virtual inertia control.

The invention discloses a drooping characteristic-based mode adaptive voltage source control method applied to a microgrid. The method is composed of improved drooping control under an islanding condition, micro-grid double-mode smooth switching control and improved drooping control under a networked state; an amplitude limiting link and a virtual inertia link are added to P-f type drooping control, so that parallel stable operation of a plurality of dropping control type micro-sources of the microgrid which operate under an islanding condition can be realized; PI adjustment is performed on the phase angle deviation and voltage amplitude deviation of an external grid and the microgrid, so that pre-synchronization frequency deviation control signal and voltage deviation control signals can be obtained; after receiving the frequency deviation control signal and voltage deviation control signals which are issued by a microgrid pre-synchronization control system, micro-source inverters perform control according to a signal translation active power droop curve and reactive power droop curve; and connection line power control is increased, adjustment is performed according to an active power reference deviation value and a reactive power reference deviation value, and reference active power reference signals and reference reactive power reference signals are obtained, and control is performed according to the signal translation active power droop curve and reactive power droop curve.

The present invention provides an inverter control method. The method comprises: regulating the angular frequency of real output voltage of an inverter based on the angular frequency and the active power of the real output voltage of the inverter and the angular frequency and the active power of output voltage of the inverter in a rated state and according to the adaptive virtual inertia control equation of the inverter, wherein the adaptive virtual inertia control equation of the inverter is formed by superposition of the inverter virtual inertia control equation and the adaptive virtual inertia coefficient equation. The adaptive virtual inertia coefficient can be subjected to adaptive continuous regulation according to the changing of the angular frequency of the real output voltage of the inverter so as to allow the angular frequency of the real output voltage of the inverter to perform adaptive continuous regulation, namely, the equivalent inertia of the real operation inverter system has smooth and continuous features so as to avoid direct sampling of angular frequency differential items, enhance the system anti-interference and overload capability, improve the frequency dynamic performance and improve the microgrid transient stability.