70results about How to "Avoid disconnection issues" patented technology

The invention discloses an operation method for safely applying a line protection device to a wind power station, which relates to the relay protection of a power plant and is provided aiming at solving the problem that the line protection device in the current system cannot meet the protective requirements of the wind power station very well. The operation method comprises the following steps of: firstly, establishing a real-time simulation model which is a virtual power grid environment, including fault points in a wind power station, a bus and transmission lines, a main transformer unit of a power generator, a current and voltage mutual inductor, an equivalent system and a simulation system; secondly; establishing an experimental detection platform including a real-time digital simulation work station, an RTDS (Real Time Digital System) real-time digital simulator, an analogue quantity output board card, a power amplifier, a line protection device, an analogue circuit breaker, a switch conversion device and a digital quantity input board card; and thirdly, accessing the line protection device to be detected to the power amplifier of the detection system, then connecting the line protection device with the analogue circuit breaker and carrying out various kinds of experiments. The experiment implemented by using the wind power station model and an onsite oscillograph of the wind power station can provide a real and accurate simulation environment so that validation possibility is improved, and therefore the line protection device to be detected can be safely used for the wind power station after detected.

The invention discloses a control system and method for low-voltage and zero-voltage ride through of a photovoltaic grid-connected inverter. A bi-synchronous rotating coordinate system is adopted to independently control positive sequence current and negative sequence current under a steady state; positive sequence voltage and negative sequence voltage dq components of power network voltage are taken as feedforward for a regulator; when low-voltage and zero-voltage ride through occurs, the control for the negative sequence current is switched into an open loop control mode; a direct feedforward control policy is adopted for the power network voltage; a feedforward control signal of the power network voltage is switched to adopt un-decomposed power network voltage dq components to replace the positive sequence voltage and negative sequence voltage dq components to be used as the voltage given feedforward; the feedforward signal is combined with the output of dq current controllers separately; and after the feedforward signal is subjected to dq/abc inverse conversion, the feedforward signal passes through a (pulse width modulation) PWM control module to be output to the inverter for controlling the inverter. According to the control system and method, the problem that the inverter is out of the power network caused by an overcurrent protection action frequently appeared in a voltage drop process when a conventional control policy is adopted is solved; and high balance of three-phase grid-connected current output by the inverter under the steady state can be ensured.

The invention relates to a wind power station LVRT (Low Voltage Ride Through) device which comprises a wind power station, electric reactors, diodes, adjustable voltage sources, a circuit breaker and a grid system. One adjustable voltage source is connected in parallel with one diode after being connected in series with one electric reactor to form one group of fault current limiting circuit; and after two groups of fault current limiting circuits are connected in series, one end of the obtained circuit is connected with the wind power station and the other end of the obtained circuit is connected with the grid system by the current breaker. The wind power station LVRT device is low in cost and easy to implement. When the LVRT function is implemented, the short current limiting capacity is improved; and by the non delay input of the current limiting electric reactors connected in series, the large-area talk around accident caused by the short circuit inside the wind power station can be avoided. The wind power station LVRT device has low requirement for the control characteristic of a unit plant; and a power electronic valve string of the wind power station LVRT device adopts a diode set string with low cost, large through-current capacity and strong short-time overload capacity, so that the system cost is reduced.

The invention discloses a method for determining the inactive compensation capacity network adaptability of a wind power plant and relates to power grid optimization analysis. Aiming at the situation that the conventional inactive capacity configuration of the wind power plant is not reasonable, the invention provides a new inactive capacity calculating method which comprises the following steps of: firstly, establishing a power grid simulation mode which is composed of a wind power plant, a box transformer substation, a current collection line, a boost transformer substation, an outgoing line and an accessing power grid system; secondly, determining an inactive configuration capacity change range by adopting the conventional theoretical calculating method; carrying out a closed loop test on a compensation capacity range value determined by using the conventional theoretical calculating method through using a simulation system so as to determine the sensitivity (of the wind power plant) to be compensated and the capacitive inactive compensation capacity (of the wind power plant) to be compensated; and introducing the sensitivity and the capacitive inactive compensation capacity into a simulation power grid model, and verifying a steady trend, a dynamic voltage fluctuation and a transient stability so as to obtain adaptive network inactive compensation configuration capacity and corresponding equipment technical requirements, thus ensuring that the inactive compensation capacity of the wind power plant can be effectively used for the inactive configuration of the wind power plant.

The invention relates to the technical field of new energy power generation, in particular to a photovoltaic power station optimization control method actively participating in power auxiliary service. The method comprises the following steps: determining a coordinated control strategy of the primary frequency modulation and the secondary frequency modulation of the photovoltaic power station AGC;determining the active power control and distribution mode of a photovoltaic power station; determining the optimal control strategy of reactive power based on AVC photovoltaic power station; determining the reactive power control and distribution mode of the photovoltaic power station. The invention has the advantages of: (1) fully utilizing the non-functional force of the inverter under the steady state condition, reducing the reactive load of the reactive power compensation device SVC/SVG, reducing the power consumption of the reactive power compensation device, reducing the auxiliary power consumption, and increasing the on-grid power quantity of the distributed photovoltaic power station; (2) guaranteeing that the reactive power compensation device SVC/SVG can reserve more reactive power adjustable degree in steady state, and can have enough reactive power compensation ability a in transient process, so as to ensure voltage stability in transient process and avoid inverter disconnection.

The present invention discloses a control method for inhibition of overvoltage of sending end power grid during commutation failure. The method comprises the steps of: when it is detected that a direct current system generates commutation failure, inputting a by-pass pair at an inverter side after commutation failure signals are obtained at the inverter side, and regulating parameters of the inverter side VDCOL according to a current instruction value during the commutation failure; emitting the commutation failure signals at the inverter side; after the commutation failure signals emitted bythe inverter side are received at a rectifier side, reducing the trigger angle limiting value at the rectifier side to 95 degrees, and regulating parameters of the rectifier side VDCOL according to acurrent instruction value during commutation failure; and after it is detected that the alternating voltage at the inverter side returns to normal, withdrawing the by-pass pair at the inverter side, cancelling the trigger angle limiting value at the rectifier side, and recovering setting of original parameters of the inverter side VDCOL and the rectifier side VDCOL. The problem is solved that a new energy device such as a fan is off-line due to generation of an overvoltage of the sending end power grid when the direct current system generates commutation failure.

The invention discloses a grid voltage feed-forward control system and control method for a chain type STATCOM. The instantaneous value of grid voltage is used as a feedforward control amount, an instantaneous voltage signal is employed by the feedforward signal in a steady state and is changed into a dp component through abc/dq, the one-order low-pass filtering of the feedforward signal is carried out in a dq coordinate system, and then an instantaneous feed-forward signal with a filtering link is obtained after da/abc inverse transformation. Through judging a grid voltage instantaneous value change amplitude and change rate, whether a current grid is failed or not is determined, and a control switching command is emitted to select different feedforward signals. The feedforward signals are accumulated to the output of a current ring to generate a modulation wave to be outputted to a modulation module to generate pulses. A problem that an equipment over-current protection action and offline are easily caused in a grid failure due to the use of a conventional control strategy by an existing chain type STATCOM can be solved, the good harmonic characteristic of the output current of the STATCOM in a steady state operation can be ensured, and the stability of equipment is improved.

The invention provides a cell handover method and device. The cell handover method comprises the steps of issuing an information list of an MTC (Machine Type Communication) cell to a terminal, therebyenabling the terminal to measure signal quality of the MTC cell according to the information list of the MTC cell; receiving the signal quality of the MTC cell reported by the terminal; and determining a relationship among the signal quality of the MTC cell, the signal quality of a serving cell of the terminal and the signal quality of a neighbour, and instructing the terminal to hand over to theMTC cell when the relationship among the three pieces of signal quality satisfies a first preset condition, wherein the serving cell of the terminal is a non-MTC cell. According to the method and thedevice, the reliability of the cell handover method can be improved.

The invention relates to a control method for a direct current voltage of a grid-side converter of a high-voltage doubly-fed power generation system. The control method for the direct current voltage of the grid-side converter of the high-voltage doubly-fed power generation system includes the following steps: 1) when a power grid voltage is located at a normal working condition, controlling the direct current voltage of the grid-side converter through an inner current loop and an outer direct current voltage loop; 2) judging whether the power grid voltage rises stably, if not, performing a step 3), if so, re-determining a proper direct current running voltage U'dc-ref and a working voltage of a Chopper component, and using the same control process as that of the step 1) to control the grid-side direct current voltage of the converter; 3) judging whether the power grid voltage appears transient change, if not, ending the control process, if so, controlling the direct current voltage of the grid-side converter through the single close-loop control of current. The control method for the direct current voltage of the grid-side converter of the high-voltage doubly-fed power generation system can be broadly used for controlling the grid-side direct current voltage of the converter.

The invention relates to a method for determining voltage feasible region based on total wind power on-grid active power flow, and belongs to the technical field of automatic voltage control of a power system. The method comprises the following steps: selecting a characteristic quantity for representing a total active power generation operation mode in a wind power region, namely active partition P<ref> which serves as the characteristic criterion of the operation mode, and identifying the operation mode of the total wind power active power output of a target region by using the characteristic quantity value; and determining the voltage feasible region of each bus in the wind power region in corresponding operation modes according to different intervals of the characteristic quantity. By the method, aiming at the problems that a tertiary voltage control mode has a poor effect on the voltage control of a wind power field, or even fails completely, the difficult problem is solved by generating the target voltage, the upper limit and the lower limit of a central bus dynamically and controlling the upper limit and the lower limit of the voltage of the bus according to the total on-grid active power of a wind power centralized access region; and a good control effect also can be achieved even in the situation of extreme voltage flurry. The method-based tertiary voltage control mode has better robustness and wider applicability, and can solve the problem of voltage control of large-scale wind power grid connection.

The invention discloses a modular direct-current grid connection topology comprising an energy storing device for a wind power station group. The modular direct-current grid connection topology comprises a first convertor station, a second convertor station and a third convertor station, wherein the first convertor station is positioned near the wind power station group; the alternating-current bus end of the first convertor station is connected with a wind power station; the alternating-current bus end of the second convertor station is connected with the energy storing device; the direct-current bus end of the second convertor station is connected with the first convertor station through a direct-current bus; the alternating-current bus end of the third convertor station is connected with a receiving end power grid; the direct-current bus end of the third convertor station is connected to the direct-current bus; the first convertor station is used for transmitting power of each wind power station to the direct-current bus; the third convertor station is used for controlling the voltage of the direct-current bus to be constant, and transmitting power emitted by each wind power station to the receiving end power grid; and the energy storing device is used for absorbing or transmitting power to stabilize the fluctuation of the wind power. The wind power stations in the system are not in alternating-current interconnection with a local power grid or other wind power stations, so that the influence range of an alternating-current fault can be limited, the wind power short fluctuation can be stabilized, and the system stability can be improved.

The invention provides a synchronous motor-based power electronic grid-connected device and a control method thereof. The synchronous motor-based power electronic grid-connected device comprises a converter bridge, an energy consumption switching device, an open winding motor and an excitation control assembly, wherein the open winding motor comprises a three-phase stator winding and a rotor; a damping winding is mounted on the rotor; the direct current side of the converter bridge is connected with a direct current power supply, and the output side of the converter bridge is connected with the input end of the three-phase stator winding; one end of the energy consumption switching device is connected with the output side of the converter bridge, and the other end of the energy consumption switching device is connected with the input end of the three-phase stator winding; the output end of the three-phase stator winding is connected with an alternating current power grid; and the rotor is connected with the excitation control assembly. The active supporting capacity of the new energy unit is improved by introducing the energy consumption switching device and the excitation control assembly.

The invention relates to the technical field of electrical equipment, and discloses an inverter heat dissipation device for photovoltaic power generation. The inverter heat dissipation device comprises a heat dissipation outer shell, wherein an inverter controller is arranged at the bottom part of the interior of the heat dissipation outer shell, heat dissipation blocks are arranged on the front side and the rear side of the inverter controller, heat pipes are evenly arranged in the heat dissipation blocks, temperature sensing pipes are arranged on the heat pipes of the heat dissipation blocksat intervals, each temperature sensing pipe comprises a pipe body, a bimetallic strip is arranged in each pipe body, a sealing ring is arranged on the upper portion of each pipe body, a front bevel gear at the upper end of each bimetallic strip is in meshed connection with a dial, a rear bevel gear at the upper end of each bimetallic strip is in meshed connection with a worm, and the right side of each worm is in meshed connection with an adjusting gear. According to the inverter heat dissipation device for photovoltaic power generation, when the temperature exceeds an early warning value, aslip sheet connector deflects to the resistor disc insulation section, a heat dissipation circuit is disconnected, a protector controls a disconnection connecting rod to reset rightwards and disconnect main power supply of an inverter circuit, an inverter controller can be prevented from being burnt, and the service life of the inverter circuit is guaranteed.

The invention discloses an off-line prevention method, user equipment and a device with a storage function. The off-line prevention method is executed by user equipment provided with a first telephonecard and a second telephone card, and comprises the following steps: when a data service is switched from the first telephone card to the second telephone card, judging whether the first telephone card meets a preset off-line condition or not; if the first telephone card meets the preset off-line condition, executing a preset operation to avoid offline of the first telephone card. Through the above mode, missed information of the telephone cards caused due to off-line conditions can be prevented.

The invention relates to a power system broadband oscillation protection method and system. The power system broadband oscillation protection method is characterized by comprising the following stepsof: 1) collecting three-phase voltage and three-phase current of a line at a wind turbine generator collection line of a wind power plant in real time, and calculating the broadband oscillation powerof the line in real time based on a dynamic time window; 2) calculating the maximum broadband oscillation power of the line and the broadband oscillation dominant modal impedance of the line accordingto the three-phase voltage and the three-phase current which are acquired in real time; and 3) based on the broadband oscillation protection action criterion, according to the calculated broadband oscillation power of the line, the maximum broadband oscillation power of the line and the broadband oscillation dominant modal impedance of the line, and cutting off the wind turbine generator participating in oscillation to complete the protection of broadband oscillation of the power system. The power system broadband oscillation protection method can be widely applied to the technical field of power systems.

The invention relates to a duplex transformer offshore wind power direct current sending-out system and a control method, and the system comprises a plurality of wind power plant booster stations which are grouped and accessed to an alternating current switch station, then are connected through two parallel connection transformers, and finally are accessed to a direct current system. When any one of the connected transformers breaks down and quits operation, the surplus power of the other connected transformer is rapidly calculated, the disconnected wind power plant booster station is determined by comparing the surplus power with the output power of the wind power plant booster station, the offshore wind power plant is controlled, the large-area offshore wind power plant is prevented from being off-grid, so the stability and reliability of direct current output of the offshore wind power plant are improved.

The invention relates to a DC energy consumption device and DC protection cooperation method in an offshore wind power flexible DC sending-out project, and the method comprises the steps: firstly determining a DC protection subarea of the offshore wind power flexible DC sending-out project comprising a DC energy consumption device, and dividing the protection of the DC energy consumption device ofan onshore converter station into a DC electrode protection area; and researching the cooperation strategy of the on-off voltage value of the direct-current energy consumption resistor, direct-current overvoltage protection and direct-current low-voltage protection, and the cooperation strategy of on-off of the direct-current energy consumption resistor and direct-current pole bus differential protection emphatically. The switching frequency of the direct-current energy consumption resistor is reduced by setting a threshold value, the impact of switching of the direct-current energy consumption resistor on a system is greatly reduced, the loss of converter station locking, fan off-grid and power grid power failure caused by power grid side faults is effectively prevented, and the reliability of offshore wind power flexible direct-current delivery engineering is further improved.