1719 results about "Power Fluctuation" patented technology

The network monitoring system collects transmission and/or receive power level information from a plurality of customer premise devices connected to the same distribution node for each of a plurality of network distribution nodes. For an individual network distribution node, the network monitoring system calculates a set of fluctuation parameters including a group power level deviation metric, e.g., a modified standard deviation ratio. The network monitoring system evaluates the generated fluctuation parameters and responds, e.g., outputting a fluctuations report, modifying a data collection profile being used by a set of customer premise devices corresponding to a distribution node, commanding diagnostics to be performed on a portion of the network and/or directing a service technician. The network monitoring system compares generated fluctuation parameters corresponding to different distribution nodes, and uses the results of the comparison to assign priority with regard to the assignment of limited available troubleshooting and repair resources.

There is provided a power control method for secondary batteries constituting, in a grid connection system supplying electric power to a power system by combining a power generator where output power fluctuates with a power storage compensator, the power storage compensator and compensating fluctuation of output power of the power generator. The method includes the steps of: dividing the secondary batteries into a “constant power control” group and a “demand responsive” group, and distributing predetermined constant input-output power out of power to be input and output provided to all the secondary batteries in order to compensate fluctuation of output power of the power generator to the “constant power control group” and the remaining input-output power to the “demand responsive” group to control input-output power of the secondary batteries respectively depending on the belonging groups.

The invention relates to the technical field of photovoltaic micro-grid control, and particularly discloses a real-time coordination and control method of a photovoltaic micro-grid system. A central real-time optimal control layer and a local control layer are involved in the real-time coordination and control method. The central real-time optimal control layer collects the voltage and frequency of an AC bus of the photovoltaic micro-grid system, the charge state of a storage battery pack, the output power of photovoltaic power generation micro-sources, the output power of the storage battery pack, the output power of a super capacitor and the real-time power of a load in real time, generates a real-time coordination and control strategy and a secondary frequency modulation and scheduling plan, and issues the strategy and the plan to all local controllers. The local control layer coordinates and controls all the micro-sources in real time, and particularly achieves the scheduling plan issued by the central real-time optimal control layer. According to the real-time coordination and control method, a micro-grid central optimizing controller can manage, coordinate and control all the local controllers in a unified mode, the micro-grid can efficiently and economically run, the output power of the photovoltaic power generation unit is utilized to the maximum extent, the output power fluctuation and the tracking load change of the photovoltaic power generation unit are restrained, the running method of the micro-grid is reasonably adjusted, and energy balance is achieved.

Methods and apparatus are provided for reducing power fluctuations during preamble training in a multiple antenna communication system using cyclic delays. A preamble having a legacy portion and a high throughput portion is transmitted (or received) on each of N antennas, wherein at least a portion of the preamble on a first of the N antennas is delayed relative to at least the portion of the preamble on a second of the N antennas, wherein the delay is non-orthogonal amount to introduce variation across the preambles transmitted on the N transmit antennas. The legacy portion may be, for example, an 802.11 a/g preamble.

In a head for thermal assisted magnetic recording device, a semiconductor laser is mounted so that the total height of the head does not become larger and light power fluctuation due to wavelength fluctuation occurs less frequently. In addition, the rise in temperature of the mounted semiconductor laser is suppressed. A semiconductor laser is placed on a side surface which is different from surfaces on an inflow end side and a trailing side, of four side surfaces of a floating slider. An entrance of a waveguide is placed on the side surface of the floating slider, to thereby cause emitted light from the semiconductor laser to directly enter the waveguide. A curved line part or a reflective mirror is formed in the middle of the waveguide so that the light which has entered the waveguide travels toward an optical near-field generating element.

After power is restored to a node in a utility network, that node employs one or more of its neighboring nodes as proxies to route a message to a central control facility of the utility. The message contains information about the restored node, and possibly one or more of its neighbor nodes. This information may include reboot counters, the amount of time that the node was down, momentary outages or power fluctuations, and/or the time of power restoration. The node that creates and initially sends the message can be the restored node itself, or another node that recognizes when a restored node has recently come back online.

A method for forecasting reduction in sunlight intensity due to cloud cover at a photovoltaic power plant is described. The method comprises determining characteristics of one or more clouds from sensors surrounding the photovoltaic power plant. The cloud characteristics are used to create a 3D map of the clouds. The 3D map in combination with information on the angle of the sun is used to create a 3D projection on the surface of the earth, resulting in a 2D surface irradiance map. The 2D surface irradiance map may be taken in successive projections or used in combination with wind speed data to forecast fluctuation in irradiance at the photovoltaic power plant. The forecasted reductions in power may be used to enact measures at the plant such as reducing the power output of inverters to prevent sudden fluctuations in the power output of the photovoltaic plant feeding the utility.

Provided is a co-scheduling strategy for multiple energy storage in a distributed light storage micro-gird system. The based multiple energy storage adopts a two-stage converter topology structure comprising a preceding-stage bidirectional DC/DC conversion unit and a back-stage DC/AC conversion unit. A bidirectional DC/DC conversion unit for a storage battery and a bidirectional DC/DC conversion unit for a super capacitor share a DC bus, and are connected with a load and a large power grid through the DC/AC conversion unit and via an LC filter. The co-scheduling method of a two-stage converter for multiple energy storage is characterized by when the distributed light storage micro-gird system is in a grid-connected mode, carrying out double filter control on the two-stage converter for multiple energy storage, controlling the energy-storage element to carry out smooth photovoltaic output power fluctuation, and carrying out adjustment on filtering parameters according to the charge state of the super capacitor and the charge state of a storage battery; and when the distributed light storage micro-gird system is in an off-grid state, controlling the energy-storage element to provide voltage and frequency support to the distributed light storage micro-gird system, the distributed light storage micro-gird system jointly providing power for the load, wherein the energy-storage element is the storage battery and the super capacitor.

A power factor correction (PFC) circuit includes an inductor, a diode, a storage capacitor, a switch and a control unit. The input power has a voltage fluctuation V₁. The storage component absorbs a first voltage fluctuation and a switch regulation circuit absorbs a second voltage fluctuation V₂. Thus output voltage from the PFC circuit is not a conventional constant voltage but a voltage of a great ripple. The PFC circuit further has a harmonic regulation unit. The harmonic regulation unit generates a voltage signal containing 3^rd harmonic. The control unit receives a feedback signal and the voltage signal containing 3^rd harmonic to generate a reference to the inductor current. Therefore, the inductor current contains 3^rd harmonic. Thus power fluctuation absorbed and released by the capacitor is smaller. As a result energy storage capacitance can be reduced significantly.

A desired value of reactive power flow between a to-be-controlled power system and an adjoining power system is determined according to measured values of the reactive power flow and an effective power flow and desired voltage values of the to-be-controlled power system and of the adjoining power system. Thereafter, a required value of a reactive power of the to-be-controlled power system is calculated according to the desired value of the reactive power flow, the measured values of the reactive power flow and the effective power flow, and the desired voltage value and a measured voltage value in the to-be-controlled power system. Thereafter, a control apparatus having an electric capacity near to the required value of the reactive power is selected from control apparatus arranged in the to-be-controlled power system to make the selected control apparatus adjust a voltage of the to-be-controlled power system. Therefore, cooperation of the to-be-controlled power system with the adjoining power system can be performed by collecting locally-existing-information, and a voltage fluctuation and/or a reactive power fluctuation in the to-be-controlled power system can be immediately suppressed.

A multicarrier communication apparatus capable of reducing an amount of information required for feedback, making a range of transmission power fluctuation small, and achieving rapid convergence on a target transmission power is disclosed. With this apparatus, subcarrier pair determination section (1142) puts a plurality of subcarriers contained in a multicarrier signal into pairs, notifies combining section (106) of information pertaining to the pairs of subcarriers, combines received power of each pair of subcarriers, and outputs combined received power obtained in this manner to command producing section (1146). Target power storage section (1144) stores target power for received power in such a manner that SIR at the subject apparatus becomes a desired SIR. Command producing section (1146) compares combined received power for the pairs of subcarriers and target received power, produces a command indicating a difference in power between these two received powers, and generates a control signal containing the produced command.

The invention relates to a microgrid energy optimization method based hybrid energy storage dispatching under different time scales. Microgrid optimized dispatching is divided into day-ahead dispatching and real-time dispatching according to different time scales; for the day-ahead dispatching, the operation plan of future 24 hours is provided one day in advance, the time granularity is 1 hour, the connecting line interaction power and the fuel cell (FC) output are optimized according to the difference between the electricity prices in the peak and valley periods, and a storage battery (SB) is dispatched to achieve low-storage high-output interest arbitrage; the real-time dispatching coordinates with the day-ahead dispatching, the microsource output is allocated according to the day-ahead plan, the time granularity is 1 minute, the power fluctuation in the microgrid is smoothened by use of a first-order low-pass filtering algorithm, the filtered fluctuating power is distributed reasonably between storage battery energy accumulation and a super capacitor by use of a moving average filtering algorithm and then reference is provided for the optimized dispatching of hybrid energy storage.

The invention provides a method for micro-grid system coordinated control based on multi-element composite energy storage. The method includes the steps that a flywheel energy storage unit is additionally arranged so that output fluctuation of voltage can be restrained; when a micro-grid system is in grid-connected operation, a battery energy storage unit and the flywheel energy storage unit restrain output fluctuation of a distributed generation unit; when the micro-grid system is in off-grid operation, the battery energy storage unit and a diesel generator alternately serve as a main power source of the micro-grid system; when grid-connected operation and off-grid operation of the micro-grid system are switched, the flywheel energy storage unit and the diesel generator provide power support. Through the method, the use rate of renewable energy sources is improved, optimal operation of power grids is achieved, instant high-power fluctuation and long time scale fluctuation of photovoltaic output are restrained, each distributed generation device is controlled in a coordinated mode, and timely, accurate and rapid coordination action of the devices can be guaranteed.

The invention discloses a wind, light and water-containing multi-source complementary micro-grid hybrid energy storage capacity optimal proportion method. According to the method, an annual output power curve of wind power generation, photovoltaic power generation and hydroelectric generation is simulated according to the distribution condition of natural resources such as wind, light and water, an annual load curve of a micro-grid is combined, system cost and power fluctuation are used as target functions, accumulator capacity and super-capacitor capacity are used as optimization variables, and meanwhile constraint conditions such as power balance constraint, maximum instantaneous power constraint, power supply reliability constraint, super-capacitor charge and discharge current and voltage constraint and accumulator SOC (System On Chip) constraint are determined to establish a wind, light and water-containing micro-grid hybrid energy storage optimization configuration model; optimized solution of the target functions is performed by using a fuzzy decision-containing multi-target planning GA-PSO (Genetic Algorithm-Particle Swarm Optimization) algorithm to obtain the optimal proportion of the hybrid energy storage capacity. Compared with the conventional GA algorithm and PSO algorithm, the method has the advantages that the convergence rate is higher and the problem of mutual conflict of the target functions in the multi-target optimization algorithm is avoided better.

The invention discloses an energy control method for an independent photovoltaic hybrid energy storage system. The hybrid energy storage system comprises a storage battery, a super capacitor, a photovoltaic power generation unit, a DC bus and a DC load. The storage battery and the super capacitor are connected in parallel with the DC bus through respective bidirectional DC/DC converters. The photovoltaic power generation unit is connected to the DC bus through a BOOST converter. After data acquisition, an energy control processor calculates the power that should be borne by the hybrid energy storage system, and then the power passes through a first-order low-pass filter. According to limit control methods of different sections, the hybrid energy storage system, under different control conditions, achieves power distribution to the storage battery and the super capacitor, maintains the stability of the DC bus, stabilizes photovoltaic output power fluctuation, maintains in-system power balance, optimizes the work of energy storage equipment to a certain extent, and prolongs the service life of the energy storage equipment.

The invention provides a composite energy storage system, which consists of a supercapacitor and a storage battery, wherein the composite energy storage formed by the supercapacitor and the storage battery has both power type and energy type characteristics; through the combined use, the charging and discharging times of the storage battery can be effectively reduced; in addition, the utilization rate of the energy storage system can be improved. According to an energy management and control optimization method matched with the composite energy storage, the total power of the composite energy storage is distributed through a low-pass filter, so that the supercapacitor and the storage battery respectively share a high-frequency component and a low-frequency component in the fluctuating power; through the two-way DC/DC1 converter constant-power control on the storage battery, the two-way DC/DC2 converter constant bus voltage control on the supercapacitor, and control strategies of the two-way DC/AC converter, the network loss of a power distribution network is reduced; the utilization efficiency of new energy sources is improved; the power fluctuation during micro power grid interconnection is effectively inhibited; the electric energy quality of a region electric network is improved; in an offline state, the stability of the voltage and the frequency of a micro power grid system can be ensured; the power balance generated during grid connection/off-grid switching is fast compensated.

The invention discloses a method for controlling energy storage type wind power station control with a synchronization property, belonging to the technical field of wind power generation control. The method is characterized in that an energy storage battery system is configured at the alternating current side of the wind power station, a control strategy based on a synchronous generator model is adopted for the inverter of the energy storage battery system, and the wind power station and the energy storage battery system are equivalent to a virtual synchronous generator, thus the wind power station has a synchronization interface property. By utilizing the method disclosed by the invention, the output power of the wind power station is smooth, and the influence of the output power fluctuation of the wind power station on the power network frequency is reduced effectively; and the property of a synchronous generator is embodied to a power network, the system power balance can be maintained automatically according to the system loading fluctuation, thus the system voltage frequency is stable.

The invention belongs to the field of wind generator power conversion device control, and relates to a constant-frequency direct power control method for a PWM converter under the condition of power grid voltage imbalance. The method comprises the following steps of: determining a sampling frequency; acquiring a three-phase power grid voltage, a three-phase power grid current and a direct-current side voltage, and calculating resultant vectors E and I of the power grid voltage and the power grid current in a three-phase static coordinate system respectively; calculating positive and negative sequence components of the power grid voltage and the power grid current; calculating an instantaneous power and an instantaneous power error; calculating a converter reference voltage, and performing inverse transformation on the converter reference voltage; performing amplitude limit on the converter reference voltage to obtain the resultant vector of the converter reference voltage after the amplitude limit; and modulating the resultant vector of the converter reference voltage after a space vector modulation algorithm is adopted for amplitude limit, and outputting the converter voltage. The method can inhibit the active power fluctuation of the system more effectively and greatly reduce the harmonic wave of the alternating-current side current; and the output converter voltage switch frequency is constant, so the output filter parameter design is simpler.

The invention discloses a photovoltaic microgrid power equalization control method based on three-end cooperative control, and the method comprises the steps: A) judging the current operation mode of a photovoltaic microgrid according to a DC bus voltage value of hte photovoltaic microgrid, a DC bus rated voltage value, an energy storage unit SOC, a photovoltaic power supply output power, and AC load power; B) carrying out the cooperative control of the working conditions of a photovoltaic power supply, an energy storage device and a grid-connected inverter in the photovoltaic microgrid according to the current operation model of the photovoltaic microgrid; C) controlling the current operation mode of the photovoltaic microgrid to be switched to an adjacent operation mode when the corresponding operation conditions are met; D) and enabling the converted operation mode to be updated to the current operation mode of the photovoltaic microgrid; and then switching to the step B). The method can enable the photovoltaic microgrid to be quickly switched to the corresponding operation mode in a seamless manner, thereby quickly eliminating the operation deviation, balancing the flow of an internal energy of the microgrid, reducing impact on the operation of the microgrid from power fluctuation, maintaining the stability of the voltage of a DC bus of the microgrid, and achieving the dynamic balance of the internal power of the microgrid.

The invention discloses a capacity optimization and auxiliary peak regulation method for a regional wind power plant group energy storage power station. The method comprises the steps that 1, a BESS (battery energy storage station) composite function charging and discharging realizing method of wind power plant group power fluctuation stabilization and power network peak regulation is considered, and a capacity optimization calculating model is built by using the BESS operation cost minimization as a target; 2, the super-short-term wind power is utilized for predication, and a real-time optimization operation model is built by using the maximization of gains when the BESS synchronously participates in the power fluctuation stabilization and the power network peak regulation as a target; 3, the cost sharing and gain distribution mode and method of the BESS system operation are provided. Through the adoption of the technical scheme, an energy storage system with the configuration required by a regional wind power plant can be planned, the economic and reasonable energy storage capability is optimized and calculated, meanwhile, an prioritization scheme that the energy storage system participates in the power network peak regulation in an auxiliary way is provided, and the reasonable and efficient operation level of a regional wind field configuration energy storage system is improved.

The invention provides a method for implementing a parallel power system stabilizer (PSS). The parallel PSS of the invention divides compensation frequency domain of the existing PSS into two sections and compensates the compensation frequency domain by two compensation branches respectively, wherein, in one compensation branch, a gain regulating link is used for improving the amplitude of a high-frequency section, while in the other compensation branch, a lag compensation parameter is used for solving the shortage of compensation in a low-frequency section. As the same as the existing PSS, the parallel PSS of the invention can improve the stability of the small perturbation of the system and inhibit the low-frequency oscillation in an interconnected system. Compared with the existing PSS, the parallel PSS of the invention improves the phase-frequency characteristic of the low-frequency section and the amplitude-frequency characteristic of the high-frequency section, thereby widening the working frequency domain of the parallel PSS of the invention, and inhibiting the reactive power fluctuation while the system is in normal operation.

The invention relates to a coordinative optimization unit combination method of energy. The energy comprises wind power, thermal power and pumped storage energy. The coordinative optimization unit combination method of the energy includes following steps: confirming a wind power output confidence interval; confirming running parameters and coal consumption characteristics of a thermal power generating unit and running parameters and running characteristics of a pumped energy storage unit; confirming combination object functions and constraint conditions of a wind power, thermal power and pumped storage energy joint optimization unit; confirming mixed integer nonlinear programming problems; confirming a starting and stopping plan of the wind power, thermal power and pumped storage energy joint optimization unit in future 24 hours. The coordinative optimization unit combination method of the energy improves unit combination reliability, guarantees that a system has enough regulation ability in real-time running so as to balance power imbalance caused by power fluctuation of wind, promotes consumption and absorption of the wind power, achieves coordinative optimization running of the multivariate energy, and thereby guarantees safety and economical efficiency of running of a power grid.

The invention relates to an energy storage optimization and coordination control method for a direct-current micro grid group. When multiple sub micro grids are operated in parallel, an energy storage system in each sub micro grid automatically adjusts power distribution according to the maximum charging and discharging power and the state of charge (SOC) of the corresponding energy storage system, and therefore the safety of the energy storage systems is improved while distributed generated power fluctuation can be smoothed and the bus voltage quality can be improved; when the energy storage systems of all the sub micro grids cannot effectively buffer the system power supply and demand, an energy storage power station needs to be connected to control stabilization of the bus voltage. According to the energy storage optimization and coordination control method for the direct-current micro grid group, the virtual impedance of droop controllers of all energy storage units in the energy storage power station is adjusted by adopting fuzzy control to achieve automatic distribution of the power among the different energy storage units and SOC balance, fuzzy input is segmented, the SOC balancing speed of the fuzzy input in different ranges is increased by adopting fuzzy control, bus voltage drop caused by droop control is compensated by adopting a bus voltage feedback control method, and the bus voltage quality is improved.

The invention discloses a method for distributing the active power of a wind-light storage transmission comprehensive power station, which is characterized in that a target optimizing distribution model is created based on a dynamic optimization objective and constraint conditions thereof; according to the set power (pset) of the wind-light storage transmission comprehensive power station, wind-light storage resource behaviors are considered; dynamic, unified and coordinated active power distribution of a wind power station, a photovoltaic power station and stored energy batteries in the wind-light storage transmission comprehensive power station is carried out, and the running of the wind-light storage transmission comprehensive power station is optimized, thus ensuring the smoothness ofthe output power, reducing the fluctuation of the output power, improving the stability of the output power of the system, decreasing the influences of the fluctuation of the output power on power grid frequency, utilizing the wind, the light and stored resources more effectively, improving the utilization rate of wind energy resources and solar energy resources, realizing the technical effects of considering the service life of power generation and energy storage equipment.