92results about How to "Reduce active loss" patented technology

The invention relates to a power loop test method for a steady-state operation test of a flexible direct current power transmission MMC (Modular Multilevel Converter) valve. The method comprises the following steps of: setting voltage amplitudes V1 and V2 of valve banks 1 and 2 and phase difference delta of the two voltage amplitudes and setting output voltage of an energy replenishing power source E2; closing an isolating switch K1 and charging a sub-module capacitor by a charging power source E1; cutting off K1 to exit E1 to finish pre-charging after the voltage of the sub-module capacitor reaches a set value; closing an isolating switch K2 and switching to the energy replenishing power source E2; meanwhile, sending out trigger pulses of IGBTs (Insulated Gate Bipolar Translator) of all sub-modules of the two valve banks according to a modulation strategy and getting a circuit in a steady-state running state; establishing voltage stress required by test at the two ends of the valve banks 1 and 2, performing energy exchange on sub-module capacitors and load reactors of two valve components and generating current stress required by the test in a loop; and cutting off K2 and exiting E2, latching the trigger pulses of the IGBTs in the sub-modules and finishing the test. The test method is simple and flexible; and a test parameter adjustment method is simple and convenient.

The invention provides a large power grid overall situation on-line integrated quantitative evaluation method based on a response. The method comprises a first step of acquiring power grid topology structural information from an SCADA system and an EMS system and establishing a corresponding relation between the power grid topology structural information and a WAMS system power grid component, a second step of acquiring present power grid operation method trend data from the SCADA system or the EMS system or a WAMS system or acquiring various preconceived trends or transient state fault time domain data from a DSA system, and a third step of dividing responding data into two operation scenes including a steady state (or a quasi-stable state) and a transient state (or a dynamic state) in a macroscopic mode, wherein static state stabilization situation assessment is carried out on a power grid through an on-line node-facing method, and transient state stabilization situation assessment is carried out on the power grid through an on-line unit-facing method. Static state and transient state comprehensive assessment indicators are constructed based on component class thermostabilization, electric parameter acceptable range and system class stabilization, the comprehensiveness and reasonability of the overall situation assessment indicators are improved, and the efficiency of overall situation integrated assessment is improved through the method that tasks are carried out at the same time.

The invention relates to a power system reactive power optimization method giving consideration to off-limit voltage correcting and system active power loss reducing, and belongs to the technical field of power system optimized dispatching control. The reactive power optimization method is based on current power grid ground state flow and includes the steps of firstly scanning a whole grid to judge whether off-upper-limit voltage phenomena exist or not, and as for off-upper-limit voltage nodes, starting reactive power adjustment computing with voltage correcting as an object to eliminate the off-limit voltage; then starting voltage increasing reactive power optimization with system active power loss reducing as an object. The reactive power optimization method meets complexity operation requirements and the requirement, for the reasonable reactive power voltage automatic control computing result, of the power grid, and can be integrated in an automatic voltage control main station system operated in a dispatching center, and therefore the system can provide a control object for a reactive power voltage control strategy in real time through optimization computing according to the operation state of the power grid at present so that the control requirement for safe, high-quality and economical operation of the power grid can be met.

The invention relates to an integrated testing circuit for a modular multi-level converter valve and a control method of the integrated testing circuit. The integrated testing circuit comprises a main circuit, a test valve and a control protection circuit, wherein the control protection circuit controls the main circuit and the test valve and performs test valve charging and on-load tests. The normal operation of the converter valve is detected and guaranteed, and when the converter valve is subjected to misoperation, an error prompt is provided through a voltage signal. Voltage-regulating, alternating current and direct current testing circuits of the converter valve are effectively integrated, and testing voltage and current adjustable converter valve charging and on-load tests are finished. The operating states of components in a positive and reverse charging circuit of the converter valve are comprehensively checked through alternating current charging, and the safety and reliability of follow-up tests are ensured. Moreover, high current is generated by utilizing reactive energy exchange, and the active loss of the testing circuits and the capacity of a testing input power supply are reduced.

The invention discloses a photovoltaic grid-connected power generation device based on a multilevel technique. The photovoltaic grid-connected power generation device comprises a photovoltaic power input unit, a direct-current bus capacitor unit, a three-phase square wave inverter unit, a transformer unit and an output filter reactor unit, wherein the photovoltaic power input unit consists of N groups of photovoltaic cell arrays and direct-current / direct-current (DC / DC) converters which realize maximum power point tracking and step-up functions; the direct-current bus capacitor unit realizes direct-current bus voltage supporting and alternating-current and direct-current energy decoupling functions; and the direct-current / alternating-current (DC / AC) conversion of the three-phase square wave inverter unit adopts a square wave superposition multilevel technique, the transformer unit is used for synthesizing the output voltage of the three-phase square wave inverter unit, unit power factor control and low distortion rate of grid-connected current are realized through the output filter reactor unit, and the islanding protection of the photovoltaic grid-connected power generation device is realized through the combination of detection voltage, detection frequency and reactive power disturbance. Therefore, the photovoltaic grid-connected power generation device can be used for high-voltage high-capacity photovoltaic grid-connected power generation systems.

The invention relates to an AC-DC parallel power transmission channel power optimization distribution method and an AC-DC parallel power transmission channel power optimization distribution system. The method comprises, firstly, obtaining a total exchange power plan between various provincial networks and recent output plans of various generator sets, obtaining recent transmission power plans of DC interconnection lines of various provinces then according to a preset AC-DC parallel power transmission channel power optimization distribution model, and, finally, issuing the recent transmission power plans of the DC interconnection lines of the various provinces to corresponding convertor stations to be executed. Compared with the prior art, the method can effectively reduce active power loss of AC-DC parallel power transmission channels between the whole province network; and a transmission power safety constraint of sections of AC interconnection lines between the various provinces can also be accurately satisfied.

The invention discloses a method for optimization control of power flow of a dual-power-supply seamless fault self-recovering type looped distribution network. The method is put forward by taking network active loss and node voltage deviation into consideration based on analysis on a dual-power-supply seamless fault self-recovering type looped distribution network power supply system. The method includes that internal relations between the network active loss and generated series compensation voltage as well as between the load node voltage deviation and the generated series compensation voltage are obtained through analysis on optimized distribution rules of the power flow of the looped distribution network; a network active loss membership function and a node voltage deviation membership function are constructed respectively to represent the optimized target degree of respective deviation; weight values of the network active loss membership function and the node voltage deviation membership function are determined according to the concern degree, and series compensation voltage solving is achieved through a global optimization method. Modeling and simulating results show that the method for comprehensive optimization control of the power flow of the looped distribution network is capable of balancing force on two sides and controlling all node voltage deviation and network loss effectively, thereby laying a good foundation for the seamless fault self-recovering technology.

The invention relates to a reactive power compensation control method of three-phase unbalance system, comprises steps of: taking pressure or current of three-phase pressure or current to count reactive power Qa, Qb, Qc and active power Pa, Pb and Pc, respectively; setting and counting a Y compensatory part Qa, Qb, Qc required by a load Delta connection part and a Y compensatory part Qab, Qbc, Qca required by a load Y connection part and then obtaining a compensation formula; making three-phase power factor close to 1 and making three-phase reactive current balance to reduce usage quantity of capacitance, adjusting Q to make compensation effect and capacitance arrangement reach optimum; comparing and judging the reactive power of the three-phase unbalance system and counting scope, and compensating capacitance of the reactive power of the three-phase unbalance system. Using the system and the method provided by the invention, asymmetric loads are scattered into different outlet points to reduce out of limits of asymmetry caused by centralized connection.

The invention discloses an offshore wind turbine grid connection method. The method includes the steps that after an offshore wind turbine converts wind energy into alternating current, the alternating current is boosted to proper voltage through a boosting transformer and connected to an alternating current bus; the alternating current bus collects the alternating current boosted by the boosting transformer; an offshore convertor station converts the alternating current collected on the alternating current bus into direct current; a submarine cable transmits the direct current converted by the offshore convertor station in a long distance; a land convertor station converts the direct current transmitted through the submarine cable into alternating current; a main transformer converts the alternating current converted through the land convertor station into a proper voltage grade, and the alternating current is connected into a main power grid. The invention further discloses an offshore wind turbine grid connection system. The problems existing in grid connection of an offshore wind plant with the long distance and large capacity are solved.

The invention relates to an electronic device, in particular to an on-line dynamic harmonic treatment device which comprises a bus, a harmonic detection loop, a power supply transformation loop, an IGBT (Insulated Gate Bipolar Translator) inverter and a main loop. When current passes through the bus, the harmonic detection loop detects the power factor and the harmonic current of a power grid, and the IGBT inverter can generate a capacitive current having the same magnitude and a different direction compared with the current of the bus for the power grid to eliminate electronics. In the invention, the electronic detection loop only works when current passes through the bus, thus lagging conditions cannot occur, and the whole regulating speed is lower than 10ms.

The invention provides a multi-target voltage optimizing method of a wind power plant cluster. The wind power plant cluster is controlled as a whole, the minimum wind power plant grid-connection point voltage deviation, the minimum wind power plant cluster area transmission loss and the maximum wind power plant cluster voltage stabilization margin serve as the target functions, a wind power plant reactive power adjustable capacity constraint and wind power plant grid-connection point voltage upper and lower limit constraints are taken into account, the voltage optimized value of each wind power plant grid-connection point is obtained through optimizing calculation, and optimal control over the voltage of the wind power plant cluster is realized. The multi-target voltage optimizing method can be integrated in a wind power plant cluster control system and provides support for safe, stable and economical operation of the wind power plant cluster.

The invention discloses an optimization configuration and operation method for DES (Distributed Energy Storage) in a photovoltaic generation based LVDN (Low Voltage Distribution Network). The method includes determining the total rated power of the DES and the total rated electric quantity of DES required by the whole LVDN; constructing a DES optimization configuration and operation model; solvingthe DES optimization configuration and operation model and acquiring the optimization configuration and operation scheme for the DES in the LVDN. According to the invention, the total rated power andthe total rated electric quantity of the DES required by the whole LVDN are determined according to requirements for node voltage allowing offset and the optimization model taking the optimal superior power grid load rate as the target and taking into account a support effect for the LVDN voltage by voltage inactive control features of the DES and limitation of the number of mounting points of the DES in the LVDN is constructed. The optimization results indicates that the optimization model can make optimization decisions on the mounting position, the rated power, the rated electric quantityand the charge / discharge state and power in different time periods of the DES at the same time; the superior power grid load rate is optimized and the active power of the power grid is reduced in a specific degree at the same time.

The invention discloses a reactive power optimization control method based on active power output of a photovoltaic power station, belonging to the technical field of photovoltaic power station operation control. The method of the invention comprises: the parameters of each photovoltaic inverter and SVG in the photovoltaic power station are obtained, The active power output P* of the photovoltaicpower station and the voltage control instruction of the grid connection point issued by the grid dispatching center (img file = 'DDA000179000293000011. TIF' wi= '126' he= '86' / ) are calculated to obtain the reactive power compensation amount of the photovoltaic power station Q*; Calculate the reactive power capacity Qmax, Qmin of the photovoltaic power station; Taking the reactive power output ofPVGU and SVG as the control object, taking the minimum voltage deviation and the minimum active power loss of photovoltaic power station as the optimization objective, and transforming the fuzzy theory into a single objective optimization problem, the reactive power optimization control model based on the active power output of photovoltaic power station is established. Differential evolutionaryalgorithm is used to solve the model.

The present invention discloses a power grid energy conservation and loss reduction control method considering reactive response capability of a charging pile. the features of a charging pile taken as a reactive resource and the reactive voltage-regulation principle are analyzed, a reactive voltage optimization model considering the day-ahead optimal scheduling and the intra-day optimal correction is putted forward, according to the mathematic model, the day-ahead optimal scheduling employs a traditional parallel capacitor set and an on-load voltage regulation transformer to reduce transmission losses, and the reactive support of the electric car charging pile is employed to reduce the transmission losses when the intra-day abnormal operation; and a time-sequence progressive reactive control scheme based on the reactive voltage sensitivity is provided, and the reactive response capacity of the electric car is employed to perform reactive optimization correction. The power grid energy conservation and loss reduction control method considering the reactive response capability of the charging pile realizes the reactive local compensation and continuous regulation and reduces the active loss of the power grid.

The invention belongs to the asynchronous motor manufacturing field. In order to solve a technical problem that a current mouse cage cast aluminum rotor has large loss, the invention provides a mouse cage cast aluminum rotor with low loss. The rotor is formed through stacking rotor punching sheets. Punching grooves of the rotor punching sheets are superposed so as to form a rotor groove. The rotor is characterized in that a copper conducting bar is embedded in the rotor groove; a cast aluminum conducting bar is formed through a cast aluminum operation in a gap between the copper conducting bar and the rotor groove. By using the rotor of the invention, there are the following advantages that the rotor possesses a low electrical resistivity and low rotor active loss compared to a traditional cast aluminum rotor; compared to a cast copper rotor, a technology of the cast aluminum rotor is simple and industrialization is convenient to realize. Simultaneously, according to a need, a proportion relation of a copper conducting bar area and a cast aluminum conducting bar area is adjusted; the resistivity is adjusted; under the condition of reducing the rotor active loss, product cost is reasonably controlled.

The invention relates to the field of power systems, and particularly relates to a C-type filter and a switch control method thereof. The C-type filter comprises a main capacitor for reactive compensation, a resonance branch circuit formed by connecting an inductor and a capacitor in series, and a damping branch circuit formed by connecting a switch and a resistor in series. The resonance branch circuit and the damping branch circuit are connected in parallel and then are connected with the main capacitor in series. A disconnection moment determination method of an additional switch is proposed based on a harmonic standard; based on an equivalent circuit relationship between the filter and a power grid and a reference impedance range of the power grid, a closing moment determination methodof the additional switch is provided. Compared with a traditional C-type filter, by using the C-type filter of the invention, active losses can be reduced, heating is reduced, and a service life of equipment is prolonged.

The invention discloses a double-fed wind farm reactive output optimization method in a system recovery process. The method is characterized in that reactive optimization of a recovered system is performed by employing a reactive adjusting capability of a double-fed wind turbine. The method includes following steps: step 1, performing analysis and deduction on a mathematical model of a double-fedwind farm to obtain a P-Q curve thereof and a quantitative relation between an active output and a reactive output thereof; step 2, establishing a double-fed wind farm reactive output optimization model which regards minimum system loss and node voltage deviation as the target by regarding the reactive adjusting range of the double-fed wind turbine and the system power flow constraint as constraint conditions; and step 3, solving the reactive optimization model by employing an artificial bee colony algorithm to obtain a system wind power reactive investment scheme. According to the double-fedwind farm reactive output scheme obtained by employing the method, the active loss and the node voltage deviation value of the recovered system can be greatly reduced, and the safety constraint of a power grid in a system recovery process can be satisfied.

The invention discloses an AVC control method and system based on coordinated control of a phase modifier and a capacitor bank, and a medium. The method comprises the following steps: if a control instruction is within a first specified threshold range, when a set of standby capacitors is brought into AVC coordinated control, the standby capacitors are switched off, and reactive power output is conducted on the control instruction through a phase modifier after power distribution; if the value of the control instruction is within a second specified threshold range, whether there is a set of standby capacitors brought into AVC coordinated control or not is detected; if there is no set of standby capacitors brought into AVC coordinated control, short-time reactive power output is conducted on the control instruction through the phase modifier after power distribution, a set of standby capacitors is switched in, and reactive power reserve of the phase modifier is released; and if there isa set of standby capacitors brought into AVC coordinated control, average output is performed by the phase modifier after the capacitor capacity is subtracted from the control instruction. Under thecondition that the change in available dynamic reactive power reserve of the phase modifier is small, the range of the control instruction can be increased and widened without greatly affecting the reactive group switching instruction of an original DC control and protection system. The method has the advantages of being good in compatibility and convenient for technical upgrade and reconstruction.

The invention discloses a reactive power coordinated control method for a wind power generator set and static var generator (SVG) equipment in a wind power plant. The reactive power coordinated control method comprises the steps of acquiring a target reactive power Delta Q of the wind power plant, controlling the SVG equipment to perform reactive power adjustment according to the target reactive power Delta Q until the reactive power of the wind power plant reaches the target reactive power Delta Q, and controlling a draught fan of the wind power generation set to substitute the SVG equipment to perform reactive power output or controlling the draught fan to increase the reactive power so as to substitute a part of the reactive power output of the SVG equipment. According to the reactive power coordinated control method, different adjustment amplitudes and adjustment speeds of the wind power generator set and an SVG are combined, the SVG is used for adjustment, the reactive power of the SVG is gradually substituted by the reactive power of the wind power generator set, so that the active power loss of the SVG is reduced, the dynamic reactive power storage of the SVG is maintained, and the internal power loss of the wind power plant is reduced on the condition that the voltage adjustment requirement is met.

The invention discloses a second-order cone operation control method for an alternating-current and direct-current power distribution network containing a power electronic transformer. The method comprises the steps that a PET-containing alternating-current and direct-current hybrid power distribution network multi-period operation control model is constructed; the injection power of different ports of the PET is controlled by utilizing the flexible regulation and control capability of the PET, so that the mutual coordination of the power between the different ports is realized, and the exchange requirement of power balance between an alternating current subnet and a direct current subnet is met; and second-order cone programming and linear approximation are adopted to carry out convex relaxation on the alternating-current and direct-current hybrid power distribution network multi-period operation control model, so that the solving efficiency of the multi-period operation control problem of the alternating-current and direct-current hybrid power distribution network containing PET can be improved. According to the invention, the system loss is effectively reduced, and the system operation economy is improved; and convex relaxation is carried out on an original nonlinear model through second-order cone relaxation and linear approximation, so that the PET-containing alternating-current and direct-current power distribution network second-order cone operation control model is provided, the accuracy is relatively good, and the solving efficiency is improved.

The invention discloses a design scheme of a single 12-pulse rectifier transformer and an equivalent multi-phase rectifier unit formed by the same. The single 12-pulse rectifier transformer is additionally provided with three small single-phase auxiliary transformers. Iron cores of the small single-phase auxiliary transformers respectively sleeve circuits of each phase of the Y winding; primary windings on the iron cores are connected with the phase winding on the lines where the iron cores are located in parallel, a line penetrating through the iron cores serve as the secondary winding of theauxiliary transformer, and when the auxiliary transformer works, an in-phase compensation voltage is generated at the secondary stage, so that the phase voltage ratio of the Y winding to the [delta]winding is close to 1 / square root of 3. Compared with any scheme at present, in the scheme provided by the invention, the optimal voltage approaching value of the Y winding and the [delta] winding can be reached, the additional loss is relatively low, and the problems that the electrical parameters and economic benefits of the unit are influenced due to equalizing current and the like are solved.

The invention relates to an electric vehicle orderly charging method based on an improved NSGA-II algorithm, wherein the method comprises the steps: taking each electric vehicle charging station as anode, building a power distribution network, taking the safe and stable operation of a power distribution network and the charging electric quantity of an electric vehicle as constraint conditions, and building a multi-objective optimization model with the minimum network loss of the power distribution network and the minimum charging cost of unit electric quantity; the electric vehicle dispatching center firstly acquires electric vehicle charging requirements of each charging station, basic loads of the charging stations and real-time electricity price data of each charging station; then an initial population is randomly generated by taking the total charging power of the electric vehicles in each time period as a variable, and the established multi-objective optimization model is solvedby adopting the improved NSGAII algorithm to obtain an orderly charging scheme of the electric vehicle. According to the method, a traditional genetic algorithm is improved, the convergence speed andconvergence precision of the algorithm are improved, and the charging cost of unit electric quantity can be effectively reduced; active loss of the power distribution network is reduced and power gridoperation efficiency is increased.

The invention discloses an intelligent temperature control heating system for a heating plate. The intelligent temperature control heating system is characterized in that a heating platform is divided into a plurality of small blocks which are singly heated through the corresponding heating blocks, a thermistor collects the temperature data of a heating region corresponding to each heating block in real time, a main controller controls the heating action of each heating block according to the temperature data, the temperature difference of each heating block is controlled in a reasonable range through balanced regulation, and the uniform surface temperature of the heating platform is realized. The intelligent temperature control heating system for the heating plate has the advantages that the heating area is extensible, the heating is uniform, the temperature difference of each unit area of the heating platform is controlled in a reasonable range, and the active loss is reduced.

The invention discloses an RC serial connection-based very fast transient overvoltage suppression method. A to-be-controlled circuit is subjected to simulation to determine circuit peak values in a transformer, an isolation switch and a bus when a circuit transformer end, an isolation switch end and a transformer side isolation switch end are connected with a series RC branch respectively; a suppression circuit connecting position is selected according to suppression requirement; and in the chosen position, simulation of the suppression effects of the RC series branch with different values is performed so as to determine the optimal suppression effect range to be used as the capacitance value and the resistance of the RC. By virtue of the suppression method, it is ensured that the peak value of the VFTO (very fast transient overvoltage) can be effectively lowered, and compared with the conventional parallel RC branch suppression method, the suppression method disclosed in the invention is lower in power consumption; and the effectiveness of the method is verified through simulation.

The present invention discloses a method capable of performing centralized monitoring on whole grid reactive power voltage state(s) by adopting an automatic voltage control system, pertaining to the field of scheduling, management and controlling of a power grid. According to the method, alarm locking signal(s) of an AVC system and over-limit information found in operation are included into a closed-loop processing system, centralized and outstanding problem(s) are analyzed, abnormality causes and solutions are found, abnormality handling processes are constantly improved, and detailed and complete treatment processes are worked out. The method can improve the operation performance of the AVC system, further improve the control level of voltage reactive power, ensure the safe and stable operation of the power grid, guarantee the qualification of voltage(s) and power factor(s) of related node(s), minimize line reactive power transmission to the greatest extent and reduce the active power loss caused by unnecessary reactive power flow(s) in the power grid. The method can be widely used in the field of the scheduling, the management and the controlling of the power grid.

The invention relates to the technical field of harmonic reactive compensation, and especially relates to a master-slave harmonic reactive compensation generation system and method which can be used for carrying out harmonic reactive compensation on a power grid. The system comprises a load module connected with an input end; at least one slave harmonic reactive compensation module connected with the input end and used for carrying out harmonic reactive compensation on the power grid; and a master harmonic reactive compensation module connected with the input end and each slave harmonic reactive compensation module and used for sampling reactive information from the input end, controlling each slave harmonic reactive compensation module and carrying out harmonic reactive compensation on the power grid. According to the invention, the compensation effect is good, and the loss is simultaneously reduced.

The invention discloses a two-stage dispatching method considering charging cost of an electric vehicle participating in voltage regulation. According to the two-stage dispatching method, an optimization model of a local control unit is built through taking power constraint, electric vehicle charging demand and an operation mode as constraint conditions by a charger during first-stage dispatchingand by taking minimum user charging cost as a target function, the minimum charging cost is obtained by model solution, the constraint condition of the electric vehicle charging cost is built on the basis and is submitted to a power grid control center, the power grid control center is used for building an optimization dispatching model of the local control unit by taking the electric vehicle charging cost and running capacitor of a substation as constraint conditions and active power loss and minimum voltage deviation of a power distribution network as target functions, the optimal dispatching instruction of the local control unit is obtained by model solution and is transmitted to the local control unit, and the two-stage dispatching process of the electric vehicle is completed.

The invention discloses a single-phase grid-connected inverter system based on a double harmonic filter. The single-phase grid-connected inverter system solves the problems that the active loss is great and the promotion of high-frequency harmonic filter effect is not obvious existing in an existing grid-connected inverter filter system. The single-phase grid-connected inverter system comprises a direct-current power supply (1), a single-phase inverter (2), a double harmonic filter (4) and a single-phase alternating-current power grid (3), wherein the output end of the direct-current power supply (1) is connected with the input end of the single-phase inverter (2); the output end of the single-phase inverter (2) is connected with the single-phase alternating-current power grid (3) through the double harmonic filter (4); an inverter side inductor (Li) of the single-phase double harmonic filter (4) is connected with the output end of the single-phase inverter (2); a grid side inductor (Lg) of the single-phase double harmonic filter (4) is connected with the single-phase alternating-current power grid (3); and a first resonance circuit and a second resonance circuit are connected between the connection point of the inverter side inductor (Li) of the single-phase double harmonic filter (4) and the grid side inductor (Lg) of the single-phase double harmonic filter (4) and the ground in parallel. The harmonic pollution to the power grid when a distributed power supply is connected into the power grid is effectively reduced.