36results about How to "Suppress power oscillations" patented technology

A network power oscillation suppressor based on photovoltaic batteries characterizes that it is a device for suppressing network power oscillation based on photovoltaic barriers, which converts solar energy into electric energy by a solar energy battery board and outputs DC voltage then to invert it to AC voltage to be transmitted to the network, in which, it can carry out active regulation to the network or carry out reactive regulation to the system since the inverter is composed of voltage source type quick switch off components and outputs part of active power to the network when operating normally and regulates active and reactive powers output by the oscillation suppressor based on the control rule when power oscillation happens to the network.

The invention relates to a DC distribution system energy storage device adaptive virtual impedance droop control method, which is applied to multi-converter parallel control in a DC distribution system. The method comprises the steps of 1) acquiring electric power parameters of the DC distribution system, establishing a double closed-loop controller which consists a voltage outer loop and a capacitive current inner loop, and establishing a DC distribution system droop control model; 2) introducing virtual impedance ZD(s) into a part between converter output current and converter reference voltage signals of the double closed-loop controller in the DC distribution system droop control model so as to act as negative feedback, and acquiring equivalent output impedance Zov(s); and 3) enabling the equivalent output impedances Zov(s) corresponding to a plurality of lines to be equal through setting values of different virtual impedances ZD(s), and thus averaging output power and power distribution of the plurality of lines in the DC distribution system. Compared with the prior art, the method provided by the invention has the advantages of shock suppression, simple algorithm, low cost and the like.

The invention provides a damping control method of a permanent magnetic direct-driven wind generating set, and is used for improving transient-state stability of an electric network. The technical scheme is as follows: the damping control method comprises active damping control and reactive damping control, wherein the active damping control is realized by quickly adjusting the active output of the wind generating set and injecting damping power into the electric network according to the variation of the electric network frequency on the basis of maximum power tracking control policy, thereby further increasing the system damping; and the reactive damping control is realized by rapidly providing reactive power for the electric network by utilizing the net side convertor of the permanent magnetic direct-driven wind generating set according to the variation of the electric network frequency, thereby inhibiting system power oscillation. According to the invention, the characteristic of independent adjusting of active power and reactive power of the permanent magnetic direct-driven wind generating set is utilized, and the system damping is increased by active and reactive adjusting, thus the problem that the regional electric network with higher wind electricity permeability is lack of system damping is well solved, the transient-state stability of the electric network is improved and the safe and stable operation of the electric system is guaranteed.

The invention discloses a control method for improving system damping characteristics of a photovoltaic energy storage power generation system in a multi-power coordinated manner. When a power grid operates normally, the energy storage system can stabilize fluctuations of photovoltaic output power, a photovoltaic grid-connected inverter keeps voltage of a DC bus to be stable, and achieves grid-connected current control. When the power grid fails, the power of the system oscillates since the photovoltaic system has no damping effect on a power system, the drop and recovery of voltage of the power grid can cause drastic fluctuations in the voltage of the DC bus, thereby affecting stable operation of the power grid. The coordinated control method provided by the invention regards DC bus voltage variation as a judging condition, achieves the switching of control modes of the photovoltaic grid-connected inverter and a storage battery during the system oscillating process. The control method can suppress power oscillation of the system, brings convenience for the photovoltaic energy storage power generation system to achieve fault ride-through, and improves system operation stability.

The present invention belongs to the field of electrical engineering and relates to a power oscillation suppression system and method of a grid-connected inverter. According to the method, a direct-current voltage differential component is fed back to a corresponding control link, and corresponding feedback parameter configuration is performed; and therefore, the suppression of the power oscillation of a grid-connected system can be realized, and the adaptability range and control parameter domain of a power grid can be greatly improved. The power oscillation suppression system of the grid-connected inverter of the invention has the advantages of obvious effects, simple structure, no increase in other external hardware costs, applicability for weak grids in a large range, and strong robustness to control loop parameter disturbances.

The invention relates to a method for restraining the torsional vibration of a rotor of a motor closed-loop speed control system. The method comprises the following steps: (1) collecting a revolving speed signal of the motor rotor through a signal collecting unit, and enabling the revolving speed signal to pass through a band pass filter unit to extract a torsional vibration component signal of the rotor; (2) enabling the torsional vibration component signal of the rotor to pass through a lead-lag unit to regulate the phase position of the torsional vibration signal, and obtaining an electromagnetic torque component signal being phase-opposite with the torsional vibration component signal of the rotor; and (3) regulating the gain amplification times of a gain amplification unit, adding the electromagnetic torque component signal into a revolving speed feedback point through an amplitude limiting unit to generate an electromagnetic torque component being phase-opposite with the torsional vibration signal of the rotor, and therefore effectively restraining the torsional vibration of the motor rotor and power vibration. According to the method, the divergent torsional vibration of the rotor can be restrained, meanwhile the power vibration due to the torsional vibration of the rotor can also be restrained, and the signal collection is simple and convenient. The method has the advantages of simple structure, lower cost, less regulation parameters, easiness in realization and the like and has a larger promotional value.

A control method of a quasi-virtual synchronous machine comprises the steps of connecting a proportional controller in parallel with an inertial link of a virtual synchronous machine to form an activepower loop PI regulator and a reactive power loop PI regulator, converting characteristic of an original integral regulator to characteristic of the PI regulator, generating angle information of thevirtual synchronous machine by an active power controller taking the active power loop PI regulator as a core, generating voltage amplitude information of the virtual synchronous machine by a reactivepower controller taking the reactive power loop PI regulator as a core, and modulating to drive a three-phase bridge-arm insulated gate bipolar transistor (IGBT) to act after Park reverse conversionon the angle information and the amplitude information. Indifference control of an active power and a reactive power can be achieved during grid-connected running and when the voltage amplitude and the frequency of a power grid are normal, inertia and a primary regulation function can be provided when the power grid amplitude and the frequency are abnormal, and power equalization can be easily achieved during off-grid running.

The invention belongs to the field of micro-grids and the technical field of motors, and especially relates to virtual synchronous generator control strategy combining with virtual inertia dynamic adjustment. The invention provides an improved virtual synchronous generator control technology. The improved virtual synchronous generator control strategy combined with the virtual inertia dynamic adjustment method overcomes the defects of traditional virtual synchronous generator control, effectively suppresses power oscillation occurring in the transient process of the microgrid, and improves thetransient stability of distributed power generation units in the alternating current microgrid. The virtual synchronous generator control strategy can be applied to the fields of multi-power-supply parallel connection, new energy microgrid and the like; and stable parallel operation between a plurality of distributed power generation units or between the distributed power generation units and various power supplies can be satisfied.

The invention discloses a method and system for controlling double-fed wind turbine generator emergency power support. According to the technical scheme, the method includes: calculating the frequencyof a power grid and the real-time active power and real-time reactive power of a double-fed wind turbine generator; according to the power grid frequency combining with dead zone setting, judging whether the double-fed wind turbine generator enters an emergency power support mode or not; if so, by the double-fed wind turbine generator, using kinetic energy stored in a rotor to perform fast powersupport; when the power grid frequency recovers to a value in the dead zone range, by the double-fed wind turbine generator, starting power recovering, and entering reactive power damping control. Themethod has the advantages that virtual inertia is achieved by the control strategy of the double-fed wind turbine generator, the double-fed wind turbine generator can fast perform emergency power support during power grid frequency disturbance, system damping is improved during frequency modulation recovering by the emergency power support combining with reactive power control, system frequency oscillation is suppressed, and the secondary impact of frequency can be prevented.

The invention discloses a system for suppressing oscillation of a power system, relating to the technical field of power systems.The system comprises an electric power signal processing module, a rotating speed deviation processing module, an energy storage module and a conversion module which are connected in parallel.The system voltage Us serves as a reference vector, the output voltage fundamental wave amplitude of a conversion module is set to be Ui, the angle of the voltage Ui of the conversion module ahead of the system voltage Us is set to be delta, the loss of a switching device, the connection reactance of a transformer and the conversion impedance satisfy Z = R + jX, and the impedance angle a = arctan (X/R). An electric power signal processing module anda rotating speed deviationprocessing moduleconnected in parallelas well as an energy storage module and a conversion module are combined; the parallel energy storage type flexible alternating-current power transmission containing additional damping control can effectively suppress power oscillation of an extra-high-voltage alternating-current line, the damping ratio of an interconnection system can be increased, power oscillation on the extra-high-voltage line can be effectively suppressed, a new technical measure is provided for safety and stability of a large-area interconnection system, and the operation safety ofthepower system is improved.

The invention discloses a coordinated control method and a device for frequency regulation and voltage regulation of a doubly-fed wind turbine generator system under the condition of a weak power network. The method comprises the following steps: detecting a power network frequency and a power network voltage of a power system; judging whether the power network frequency crosses a frequency dead zone; judging whether the power network voltage crosses a voltage dead zone; and judging whether the power network voltage crosses a voltage dead zone. If the grid frequency crosses the frequency deadzone and the grid voltage crosses the voltage dead zone, the grid frequency is regulated by the active power control of the wind turbine generator system, and the grid voltage is regulated by the reactive power control of the wind turbine generator system. If the grid frequency does not cross the frequency dead zone and the grid voltage crosses the voltage dead zone, the grid voltage is regulatedby the reactive power control of the wind turbine generator system, and the active power damping control of the wind turbine generator system is carried out. The technical proposal disclosed in the present application can improve the frequency and voltage stability of the power system.

The invention relates to a virtual synchronous generator power decoupling method based on single rotation angle virtual power. As a fixed rotation angle is adopted in the virtual power conversion, theimpedance angle of the output impedance of the inverter is not considered, the sensitivity to the output impedance is small, and the design is simple and easy to realize. The dynamic and static stability of the system is ensured by using the inertial structure of the virtual synchronous generator algorithm to solve the weak decoupling problem caused by the fixed rotation angle. The invention hasthe advantages of high control accuracy, good tracking effect, effective suppression of power oscillation, damping support for power grid and the like, and is suitable for connecting new energy sources such as solar power generation, wind power and the like into a medium-low voltage microgrid. The method can weaken the coupling degree of the output power of the inverter when the system is connected to the medium-low voltage microgrid, thereby restraining the oscillation of the output power, improving the dynamic and static stability of the whole inverter system, and ensuring the safe and reliable operation of the inverter system.

The invention discloses a grid-connected and isolated island control method of a single-phase parallel inverter. The grid-connected and isolated island control method comprises three parts including application of an inverter, grid-connected operation control and isolated island operation control. The grid-connected and isolated island control method adopts current closed-loop control during grid-connected operation, and realizes zero steady-state error adjustment by means of a quasi-PR regulator; the grid-connected and isolated island control method adopts droop control and combines virtual inductance to eliminate influence of inconsistent parameters of line impedance in an isolated island operation mode, and realizes the purposes of power sharing and circulating current restraining. Compared with the traditional extraction method, the grid-connected and isolated island control method adopting hybrid filter average power extraction can effectively suppress power oscillation and improve the electric energy quality of the system.

The invention discloses a grid-connected control method for a multi-machine parallel virtual synchronous inverter. When each virtual synchronous inverter is connected to a main power network in parallel, the voltage synchronization between each virtual synchronous inverter and the main power network can be realized by using the phase angle compensation amount and the angular frequency synchronouscompensation amount. In addition, the current virtual inertia of each virtual synchronous inverter is adjusted to the target virtual inertia by utilizing the equivalent reactance between each virtualsynchronous inverter and the main power network and the maximum angular frequency compensation amount, so as to achieve the purpose of suppressing power oscillation between each virtual synchronous inverter and the main power network. Therefore, when each virtual synchronous inverter is connected to the main power network, the synchronization between the output voltage of each virtual synchronousinverter and the voltage of the main power network is ensured, and the power oscillation problem caused by each virtual synchronous inverter can be avoided when each virtual synchronous inverter can not be connected to the main power network. In addition, the invention discloses a grid-connected control device for a multi-machine parallel virtual synchronous inverter, which has the effect as above.

The present invention relates to an application of the static reactive compensator, concretely presents a method for regulating the static reactive compensator used by the power transmission system. The method comprises the following procedures: regulating the reactive power output Q0 of the TCR branch line according the current operation voltage of the power transmission system, regulating the reactive power output delta Q of the TCR branch line according to the signal reflecting the oscillating mode of the power transmission system, inputting the total reactive power outputting signal which is obtained after the overlapping of the reactive power output Q0 and the reactive power output delta Q into a trigger pulse circuit, and realizing the regulation to the SVC through the regulation to the trigger pulse circuit. The method according to the invention realizes the combination control and regulation to the stable reactive voltage and static stability of the power transmission system, and reduces the interrelationship caused by the combination SVC control and regulation by the traditional voltage regulation strategy and auxiliary control strategy. Not only that the stable voltage of the power transmission system and the reactive power output are in the qualified operation range is realized, but also the power oscillation of the power transmission system is effectively inhibited.

The invention particularly relates to a control system and method for restraining power grid power oscillation based on a photovoltaic power generation system. The system comprises a photovoltaic power generation system, which comprises a photovoltaic inverter and a photovoltaic cell panel which are connected, wherein the output end of the photovoltaic power generation system is connected betweentwo adjacent impedance elements in a power grid, the photovoltaic inverter judges whether the power grid is in a power oscillation state according to the frequency change of the power grid, PID adjustment is conducted on the frequency of the power grid in power oscillation through the photovoltaic power generation system, and the purpose of restraining power grid power oscillation is achieved. Themethod comprises the steps that a photovoltaic inverter end is connected into a power grid, the initial value of useful power output by a photovoltaic power generation system is set to be P0, the initial value Q of reactive power output by the photovoltaic power generation system is set to be 0, and omega ref is set as the rated angular frequency of a synchronous generator, namely the angular frequency corresponding to the frequency 50Hz of the power grid. The system adjusts the active power of the synchronous generator of the power grid according to the power grid operation condition.

The invention discloses a power oscillation suppression method and system, a controller and a storage medium. The method comprises the following steps: acquiring a voltage signal uabc of a power system, and converting the voltage signal uabc into a voltage signal udq of a two-phase coordinate system; the voltage signal udq is processed to obtain a signal of oscillation frequency, and the signal is subjected to phase correction and gain to be superposed to the signal to form a dq-axis current instruction; determining whether the oscillation amplitude of the signal is reduced or not; if the oscillation amplitude of the signal is reduced, adjusting the angle and gain of phase correction; and if the oscillation amplitude of the signal is not reduced, adjusting the angle and gain of phase correction in the opposite direction, and finally finding out a group of parameters capable of reducing the oscillation amplitude of the signal to the greatest extent. According to the embodiment of the invention, the power converter can be optimized through a control algorithm, the output impedance of the power converter can be intelligently adjusted, and the power oscillation of a power system can be effectively suppressed.

The invention discloses a virtual synchronous motor control method and device based on virtual impedance self-adaption, and the method and device are applied to each inverter in a virtual synchronous motor multi-machine system, and the method comprises the steps: building a virtual synchronous motor controller which is used for controlling the inverters to form a virtual synchronous motor; obtaining the angular frequency of the neighbor virtual synchronous motor, and constructing virtual impedance for the local virtual synchronous motor according to the angular frequency difference between the local virtual synchronous motor and the neighbor virtual synchronous motor; and finally, through the constructed adaptive virtual impedance, the output equivalent inductive reactance of the local virtual synchronous motor is changed. According to the invention, the frequency dynamic performance of the virtual synchronous motor can be improved, so that the power oscillation among the multiple virtual synchronous motors is inhibited.

The invention discloses a photovoltaic virtual synchronous generator control strategy of a two-stage photovoltaic power generation system. A control strategy combining photovoltaic array virtual impedance characteristic disturbance and flexible power point tracking control is adopted in a preceding stage DC/DC link, when the illumination condition changes, a photovoltaic array stable working pointis positioned according to the supply and demand balance relation of the source power and the load power, and the voltage of a direct current bus is kept stable. An improved virtual synchronous generator control strategy based on preamble differential control is adopted in a post-stage DC/AC link, and system power frequency oscillation in the transient transition process is restrained.