55results about How to "Reduce active power" patented technology

The invention belongs to the technical field of wind power generation, and discloses an over-speed load-reducing control variable parameter virtual inertia control method for a doubly-fed wind generator. According to the over-speed load-reducing control variable parameter virtual inertia control method for the doubly-fed wind generator, over-speed load-reducing control is used, active power is reserved for use, and the rotation speed of a fan is larger than the rotation speed obtained when maximum power tracking control is used. When the frequency of a system is reduced, virtual inertia control enables the speed of a rotor of the fan to be reduced, and then stored rotary kinetic energy is released; meanwhile, the rotation speed of a wind turbine is reduced, and a running point is close tothe maximum power tracking point. According to the method, the change of the frequency of the electric power system can be quickly responded by adopting virtual inertia control, and the power output is quickly changed before the action of a speed regulator of a synchronous machine. The doubly-fed wind turbine generator using the comprehensive control method can be used for more effectively reducing the fluctuation amplitude of the frequency, and a doubly-fed wind turbine generator using common inertia control cannot quickly release or reduce a large amount of active power.

A wind park with a plurality of wind energy plants, which each have one plant control, which presets a desired value for the active power to its wind energy plant, and with a park control, which presets a desired value for the active power to be generated for each plant control and limits the active power fed by the wind park to a preset value, by shutting down a first group of wind energy plants and presetting a desired value for the active power to a second group of wind energy plants at a time, characterised in that the park control starts the wind energy plants of the first group again when the sum of the actual values of the active power of the wind energy plants of the second group has reached the preset desired value and/or a predetermined time duration has elapsed.

The invention belongs to the technical field of wind power generation, and discloses a comprehensive control system adopting a doubly-fed wind generator participated in power grid primary frequency modulation. The control system comprises a rotor rotary speed control module, a simulation inertia control module, a droop control module, a rotary speed protection and power determination module and apitch angle control module. After the wind generator is participated in frequency modulation, the power grid inertia is equivalently enlarged, so that the doubly-fed asynchronous wind generator can have inertia response on the power grid frequent as the conventional synchronous generator, thereby lowering change rate of the power grid frequency; and by controlling the rotary speed and the pitch angle, the wind generator output is lowered, so that the wind generator has certain active backup capacity to be participated in primary frequency modulation, thereby lowering steady-state error of thefrequency.

A method of controlling a wind power plant, the wind power plant having a plurality of wind turbines and being connected to a power grid is provided. The method includes (a) detecting a grid frequency instability, (b) selecting a subset of wind turbines, (c) modifying a power reference for each wind turbine in the selected subset of wind turbines to respond to the grid frequency instability, and (d) applying the modified power references to the corresponding wind turbines in the selected subset of wind turbines. A wind power plant controller, a wind power plant, a computer program, and a computer program product are also provided.

The invention discloses an active distribution network (ADN) voltage real-time fuzzy control method. The method comprises steps: according to the maximum and minimum values of feeder voltage uploaded by each feeder, the maximum voltage and the minimum voltage of the distribution system are put forward, if certain feeder voltage exceeds a threshold, a reactive power fuzzy controller FQC for DG (distributed generation) is started, and reactive power is injected or absorbed through the DG; and if the reactive power fuzzy controller FQC for the DG can not restore the voltage to a normal level and deltaVsys</=deltaVmax-deltaalpha, a transformer on-load tap changer fuzzy controller FOC is started, the transformer on-load tap changer OLTC completes a voltage regulating task, or otherwise, an FPC is started, and the deltaVsys is reduced, wherein the deltaalpha is an adjusting value of the tap changer. The main control unit of the invention has a simple control algorithm, the needed communication data are few, the calculation amount is small, the decision-making time is short, problems of over voltage and low voltage caused due to mutual action between the OLTC and the DG can be lessened, and the consumptive ability towards the DG by the ADN can be improved.

A multi-agent system based distributed voltage control method for an active power distribution network comprises the steps of: analyzing the voltage sensitivity of any node of a radial power grid; taking the minimum area control cost as a target function by each agent in a multi-agent system, and performing voltage coordination control of the active power distribution network, wherein the target function consists of two parts, namely the voltage cost and the power cost, the voltage cost is used for constricting the voltage of each node, and the power cost is used for reducing the reduction of the active power of distributed generation (DG); and according to a voltage coordination control algorithm in each agent and a coordination result of each agent and adjacent agent, making a decision for enabling the voltages of all the nodes in the power grid to be within the set range by each agent, and reducing the reduction of the active power of the DG on the premise of voltage control. The method can not only solve the problem of voltage excess of the active power distribution network but also reduce the reduction of the active power of the DG, and ensures the economy for power distribution network operation as far as possible.

The invention relates to an integrated high-power chopper, comprising a plurality of high-power choppers mutually connected in parallel. The high-power choppers are of an easily dismounted whole box-type part structure comprising a plurality of high-power IGBT (Insulated Gate Bipolar Transistor) modules, filter capacitors and a cooling device, wherein the grids of the high-power IGBT modules are connected to a PWM (Pulse Width Modulation) control circuit board; the high-power IGBT modules, the cooling device and the filter capacitors are intensively and fixedly arranged in a first box; the PWM control circuit board is arranged in a second box; the first box is provided with a plurality of openings so that the electrode conductors of the collectors of the IGBT modules and the electrode conductors of the filter capacitors can be exposed out of the first box; and the pipeline interface of the cooling device is exposed out of the first box through the openings. The invention also provides a high-frequency switching power supply comprising an uncontrolled rectifier and a filter circuit connected with the uncontrolled rectifier, a plurality of integrated high-power choppers are mutually connected in parallel and/or in series; and the cooling device of the integrated high-power choppers is connected with a cooling medium conveying pipeline.

The invention belongs to the technical field of wind power generation, and relates to a low-voltage ride-through improvement device and a control method thereof. The device includes a controller, an incoming line circuit breaker, an outgoing line circuit breaker, a fast transfer switch, a bypass switch, an isolation circuit, an energy absorption circuit and a synchronous circuit. When low voltage ride-through occurs, the device The control method consumes the active power generated by the fan through the energy absorption circuit, and synchronizes the voltage of the fan and the grid through the synchronous circuit. The invention makes it possible for the wind turbine not to be disconnected from the power grid when the low-voltage ride-through occurs, and to maintain uninterrupted grid-connected operation, so as to realize the protection of the wind power generating set equipment and maintain the stability of the power grid.

The embodiment of the invention discloses a micro-grid load reducing method. The method comprises the following steps: monitoring the grid frequency of a micro-grid; receiving operation parameters ofthe grid sent by an intelligent monitoring terminal; when the frequency of the grid decreases to a set frequency value, obtaining an active power shortage according to the operation parameter of the grid; according to the active power shortage and the priority order of shedding load, determining a load to be removed; and transmitting a load shedding instruction for the load to be removed to the intelligent monitoring terminal. The embodiment of the invention also discloses a micro-grid load reducing device and system and a storage medium.

A DRAM is disclosed which includes a single ended bitline structure, a single ended global bitline structure, primary sense amplifiers with data storage and data write-back capability and with capability to decouple from the global bitlines, a full-wordline I/O structure where essentially all memory cell that belong to the same wordline are being operated on, and a pipelined architecture. The DRAM further includes a small voltage swing design. The primary sense amplifiers can include more than one amplification stages. Such a DRAM is suitable for applications in conjunction with processors as an embedded DRAM.

The invention provides a method for comprehensive evaluation of quiescent voltage stability and power angle stability by using resistance margin, belonging to the field of a power system. Based on a power flow quotation, the dynamic characteristic of system power is considered to be injected, relatively comprehensive dynamic equivalence is carried out on the system, from a view of a PV node, the relatively comprehensive dynamic equivalence impedance of the system and the resistance margin index of the node are calculated, and according to the resistance margin index of the node, whether the quiescent voltage and the power angle of the system are subjected to instability is rapidly judged, or the stability degree of the power angle of the PV node is judged. During online application, the calculation of the resistance margin index is independent of the prior knowledge of a load mode in the system. The method can be applicable for online analysis control and offline simulation analysis of the power system, system running and scheduling persons can conveniently take effective measures, the stability level of the system is improved, system planning is facilitated, the scheduling persons can conveniently adopt a reasonable design and running scheme, and the comprehensive static stability level and the economy of system running are improved.

The invention discloses a commutation failure suppression method and a system based on the current change rate. The method comprises the steps of subjecting the DC current obtained by the measurement of a conventional DC unit control system to derivation, and multiplying the DC current by an additional power coefficient to obtain the additional power of a flexible DC unit; subtracting the additional power of the flexible DC unit from an active power reference value originally input for the active power outer-loop control of the flexible DC unit so as to obtain a new active power reference value for the flexible DC unit; adopting the new active power reference value as an input for the active power outer-loop control of the flexible DC unit; and finally controlling the active power of the flexible DC unit. According to the technical scheme of the commutation failure suppression method and the system based on the current change rate, when the DC current of a conventional DC unit increases rapidly, the active power of the flexible DC transmission is reduced. Meanwhile, the short-circuit ratio of the system is increased, namely the strength of the AC system is enhanced. Therefore, the occurrence probability of conventional DC commutation failures is reduced.

The invention discloses a hybrid DC transmission-based fan grid-connected system. In the operation process of an existing hybrid direct-current system, fluctuation of an inverter side DC voltage is caused by fluctuation of a network voltage, so that fluctuation of a DC is caused and a commutation failure of an LCC is easily caused. The hybrid DC transmission-based fan grid-connected system comprises a rectifier station, an inverter station, a DC line and a wind turbine generator, wherein the rectifier station comprises a modular multilevel converter MMC, a rectifier side DC reactor and a rectifier side transformer; the inverter station comprises the line commutation converter LCC, an inverter side DC reactor and an inverter side transformer; the hybrid DC transmission-based fan grid-connected system is characterized in that the modular multilevel converter MMC is controlled by a stator module capacitor voltage and a constant DC at a DC side; and a permanent magnet direct-drive fan is controlled by a low voltage drop power. According to the hybrid DC transmission-based fan grid-connected system, a DC increase is suppressed by virtue of a constant DC control of the MMC and low voltage drop power control of the fan; and the probability of the commutation failure of the hybrid DC is reduced.

The invention discloses a control system and method of a direct current load system in response to a frequency modulation requirement of a power grid in a manner of intervals. The system comprises a main circuit system and a control system, the main circuit system comprises a rectification module, a DC/DC module and a direct current load, the control system comprises rectifier control, DC/DC control and direct current voltage droop control, the system performs frequency modulation in the manner of intervals through voltage droop control of the direct current load, and the work mode comprises five operation modes including constant-voltage operation, boosted frequency modulation, voltage-reduction frequency modulation, under-voltage protection and overvoltage protection. According to the system and method, the terminal voltage of the direct current load and the frequency of the power grid are coupled, a rectifier load participates in a frequency modulation process of the power grid as much as possible in the condition of satisfying safe operation and basic operating requirements so that the stability of the power grid can be improved, the control method is simple, the circuit structure is clear, the operation is flexible, the response is rapid, and the application value is good.

The invention belongs to the technical field of circuit protection and discloses a protection device and a method of a self-powered circuit. The protection device of the self-powered circuit is provided with a measuring circuit system. The measuring circuit system adopts a special line section. The current acquisition and analysis system uses intelligent digital ammeter to measure the current of the measurement circuit. The electric energy consumption acquisition and analysis system uses an electric energy meter to measure the electric energy consumed by the measurement circuit, and the temperature detection system uses a temperature sensor and a single chip microcomputer to measure the real-time temperature of the circuit, intelligently processes the collected data through an intelligentprocessing system and transmits the collected data to an alarm system, and displays the terminal. The invention measures each index of the measuring circuit and intelligently monitors and processes, and indirectly protects the self-powered circuit.

The invention discloses a low-voltage ride-through method and device for a feed pump turbine power generation system. The low-voltage ride-through method comprises the following steps: detecting the voltage and current of a power grid; judging whether the power grid voltage and the power grid current exceed corresponding threshold values or not; and if the power grid voltage and the power grid current both exceed the corresponding threshold values, switching a direct-current voltage control outer ring of the power generation system to a first converter, and meanwhile, switching rotating speedcontrol outer rings of a water feeding pump, a steam turbine and a power generator to an air inlet valve of the steam turbine to realize low-voltage ride-through of the power generation system. According to the invention, the input active power can be rapidly reduced when the power grid has a low-voltage fault and the grid-connected power is reduced, so that the rotating speed of the power generation system is stabilized, the converter is prevented from being damaged by excess power or the rotating speed is prevented from rising, the robustness of the power generation system can be improved, the adjustment mode is simple, and the dynamic response of the control process is rapid.

The invention discloses a low-voltage combined ride-through control method and system for a wind power low-frequency power transmission system. The control system is used for monitoring a power grid voltage signal in real time; if a low-voltage fault occurs, a current auxiliary controller is designed to solve the reactive current injection problem according to the degree of voltage drop, a concentrated energy storage device is adopted on the low-frequency side of the converter, an energy storage system is combined with a draught fan to control and absorb residual unbalanced power, and during low-voltage ride-through, part of power which cannot be transmitted due to capacity limitation of the current converter is stored in the storage battery; if the fault is eliminated, the energy storage device is allowed to release energy in a fixed power mode, and the energy is fed back to the power grid. According to the control strategy, the reactive current injection requirement can be ensured during low voltage ride-through, unbalanced power is transferred, redundant power is fed back to a power grid after a fault is ended, and the control strategy is very suitable for multiple voltage drop faults or faults with long voltage drop duration.