35results about How to "Meet the requirements of grid connection" patented technology

The invention provides a day-ahead wind speed multistep prediction method fused with numerical weather prediction, and belongs to the technical field of wind speed prediction. The problems that an existing method is directly fused with numerical weather prediction, the prediction error is large, and the prediction precision of wind electricity power is low are solved. According to the technical scheme, the method comprises the steps of analyzing the information effectiveness of an original wind velocity sequence, determining the predictability time duration of a statistic forecasting model, obtaining the wind speed prediction result within a predicable time duration, conducting information effectiveness analysis on a numerical weather prediction model, determining the predicable time duration of the numerical weather prediction model, obtaining the wind speed prediction result within the predicable time duration, establishing a day-ahead wind speed fusion prediction model according to the wind speed prediction result and predicting the actual wind speed. The day-ahead wind speed multistep prediction method fused with numerical weather prediction is suitable for predicting the wind speed within day-ahead 24 hours in the future.

The invention relates to an inverter control method based on fuzzy PCI (Proportional Complex Integral) and PR (Proportional Resonance) parallel composite control. The inverter control method comprises the steps of S1, acquiring a current three-phase grid-connected current under a three-phase static coordinate system in real time; S2, acquiring a grid-connected current instruction under the three-phase static coordinate system to obtain an AC error signal under the three-phase static coordinate system; S3, acquiring a first current value under the three-phase static coordinate system after the AC error signal passes through a PR controller; S4, acquiring a second current value under the three-phase static coordinate system after the AC error signal passes through a PCI controller; and S5, acquiring a composite control current value under the three-phase static coordinate system after the first current value is added to the second current value, and inputting the composite control current value to a PWM (Pulse Width Modulation) module. Compared with the prior art, the inverter control method has the advantages that a coordinate conversion link can be omitted, the inverter control method can be directly applied to the three-phase static abc coordinate system, the control stability of a system is ensured, and the waveform quality, the tracking precision and the power factor of the grid-connected current are improved.

The invention discloses a cascaded non-output transformer in-phase power supply system. The system is mainly composed of a power electronic conversion device cascaded with more than one three-phase-single-phase AC-DC-AC converter. The cascaded power electronic conversion device is directly connected to the traction catenary. Through the multi-module cascaded structure, the improvement The voltage level of the output converter is improved, so the output transformer can be eliminated. Since the output voltage amplitude, phase, and frequency can be controlled, the catenaries of adjacent substations can be directly connected to form a through traction power supply network. The present invention proposes a three-phase-single-phase converter structure suitable for arbitrary level diode clamping circuits. The structure includes a DC voltage stabilizing and equalizing auxiliary circuit, which can be realized under any power factor condition, especially when transmitting active current. The goal of voltage equalization and voltage regulation of each DC capacitor ensures that active power transfer or reactive power output can be achieved under any modulation depth.

The invention provides a minimum variance filtering-based self-adaptive phase-locked loop method and system. The minimum variance filtering-based self-adaptive phase-locked loop method comprises the steps of converting a harmonic-containing power grid voltage to a two-phase static coordinate system from a three-phase static coordinate system so as to obtain voltages v<Alpha> and v<Beta>; and allowing a voltage under the obtained two-phase static coordinate system to pass through a minimum variance filtering module, extracting a fundamental wave component from a voltage containing low-order harmonic, inputting the fundamental wave component to a self-adaptive module with three outputs, obtaining a frequency of the voltage by a self phase-locked loop module, and obtaining a positive sequencecomponent and a negative sequence component of a fundamental wave of the power grid voltage. By the minimum variance filtering-based self-adaptive phase-locked loop method, the amplitude and the phase angle of the power grid voltage can be accurately and rapidly detected when a three-phase unbalanced fault occurs in the power grid voltage, the phase angle and the frequency of the power grid voltage and the amplitudes of the positive sequence component and the negative sequence component which are generated by harmonic also can be accurately and rapidly detected under the condition that harmonic exists in a city power distribution network, the phase-locked loop has rapidness and accuracy, and the grid-connected requirement of a photovoltaic power station can be met.

The invention relates to a capacitor voltage feedforward control method of a grid-connected inverter under a weak power grid. The method belongs to the field of grid-connected inverter control, and comprises the following steps: S1, performing feedback control by using inverter side current i1, and performing phase locking, active damping and feedforward compensation by using capacitor voltage uCto obtain a capacitor voltage feedforward control system of a grid-connected inverter under a weak power grid; S2, performing active damping negative feedback design under a weak power grid on the capacitor voltage feedforward control system obtained in the step S1; and S3, on the basis of the step S2, designing a capacitor voltage feedforward compensation control strategy for the capacitor voltage feedforward control system. On the premise of ensuring the performance of the control system, the use of voltage and current sensors is reduced, and the hardware cost of the system is reduced; and the dynamic performance and stability of the control system are improved, so that the grid-connected inverter always has enough stability margin under the characteristic that the impedance of the powergrid changes in a relatively wide range.

The invention discloses a multi-gear transformer type voltage drop device which comprises a voltage drop device, a signal measuring module and a device protective module. The voltage drop device comprises a primary side controlled current source, a secondary side controlled current source, a primary side field winding, a secondary side field winding, a drop characteristic setting module, a three-phase impedance calculation module and a three-phase current calculation module. The primary side controlled current source is connected with voltage of power supply grid through a breaker, the secondary side controlled current source is connected with the input end of a tested device, the drop characteristic setting module is used for setting the voltage drop depth, a failure type, the drop speed and the drop time, the three-phase impedance calculation module is used for calculating impedance of a transformer three-phase winding, the three-phase current calculation module is used for calculating the current of the transformer three-phase winding, electrical parameters collected by the signal measuring module are sent to the device protective module, and the signal measuring module is used for protecting the device against the possibly-occuring faults. The multi-gear transformer type voltage drop device can simulate voltage drop experiments with different depths under various faults, and meet the penetrating testing requirements of low voltage of a wind motor set.

The invention discloses a cut-through type cophase power supply system for cascaded input-free and output-free transformers. The system is mainly composed of a power electronics conversion device with three phases connected in parallel after each being cascaded with one or more AC-DC-AC converters of single phase-single phase structures. The three phases of the cascaded power electronics conversion device are directly connected with a traction contact net after being connected in parallel. The single phase-single phase AC-DC-AC converters can bear high voltage levels through the multi-module cascaded structure; meanwhile, the voltage levels output by converters are improved; thus, input and output transformers can be omitted, power required for locomotive loads is borne by the three phases on average, and energy can flow in two directions. Due to the fact that amplitude values, phases and frequencies of the output voltage can be controlled, contact nets close to substations can be directly connected to form a cut-through traction power supply network. By means of the cut-through type cophase power supply system, the input and output transformers of the traction substations can be omitted, the defects that the transformers in the traction substations are large in size, heavy in weight, troublesome to overhaul and high in manufacturing cost are overcome, the capacity of the traction substations is easily improved, and the running cost of the substations is reduced.

The invention belongs to the wind electric power prediction technology field, and particularly relates to a short period wind power prediction system based on a covariance preferable combination model. The short period wind power prediction system based on a covariance preferable combination model comprises a data collection and storage model, a covariance preferable combination prediction module, a power prediction error analysis module and a real-time communication module. The data collection and storage module respectively transmits the collected data needed by wind power prediction and error analysis data to the covariance preferable combination prediction module and the power error analysis module to perform prediction on the wind power; the prediction result is transmitted to the power prediction error analysis module; the prediction data is transmitted to the real-time communication module; and the real-time communication module transmits the prediction data to a dispatching center in real time for service. The system and the method of the invention are simple and practical; the short period wind power prediction system is highly efficient and convenient and has function of real-time communication and self-regulation; the accuracy of the prediction algorithm is higher than that of the single physic model and the statistic model; and the development of wind power prediction is benefited.

The invention provides a wind power plant primary frequency modulation control method and a control system. The method comprises the steps: adjusting the active output of a wind turbine generator through a primary frequency modulation host, an active power automatic control system (AGC system) and an energy management platform according to a dispatching instruction and the measurement information in the wind power plant, and achieving the primary frequency modulation function of the wind power plant so as to meet the grid connection requirement of the wind power plant. The control system collects in-station measurement information of the wind power plant, especially grid-connected point voltage and current information, calculates a grid-connected point system frequency and a frequency change rate through a high-precision frequency measurement device, and obtains a total active power adjusting quantity required by the wind power plant according to a frequency droop and virtual rotational inertia control strategy. And the total active power adjusting quantity is superposed to an AGC system instruction value, is output to an energy management platform, the output of a wind turbine generator is adjusted, a primary frequency modulation function of a wind power plant is realized, and system frequency recovery is supported.

The invention provides a grid-connected photovoltaic inverter MPPT control method capable of adjusting output power along with power grid frequency. The method comprises steps: power grid voltage and output current of an inverter are acquired, and the power grid frequency and the current output power of the inverter are calculated; the relationship between the current power grid frequency and limited frequency is judged, and a different adjusting method is adopted according to the current power grid frequency. The method has the advantages that the output power can be dynamically adjusted according to changes of the power grid frequency; if in a limited frequency range, the traditional MPPT control method is adopted; and if exceeding the limited frequency, the output power is linearly reduced according to the changes of the power grid frequency, and related requirements of a photovoltaic grid-connected power generation system can be met.

The invention belongs to the technical field of wind power forecast and specifically relates to a short-term wind power prediction method based on covariance. The method is characterized by obtaining data, comprising real-time wind power data, numerical weather prediction data, real-time network data and wind tower meteorological observatory data, of a wind power plant in real time; carrying out covariance calculation on the numerical weather prediction data, the real-time network data and the wind tower meteorological observatory data obtained in real time, wherein the covariance calculation prediction carries out wind power prediction based on an NWP space difference model, a BP neural network model and an LS-SVM model respectively; and carrying out error analysis on the real-time wind power data and covariance calculation prediction three-model data through weight distribution combination to obtain a final prediction result. The precision of the used prediction algorithm is higher than that of a single physical model and a statistical model, thereby facilitating development of wind power prediction. The method can solve the problem of large error of the single prediction model, is high in predication precision and meets grid-connection requirements of the wind power plant.

The invention relates to a hybrid energy storage power control method for stabilizing photovoltaic power fluctuation. The method comprises the following steps: wavelet packet decomposition is carriedout on photovoltaic power generation power signals in a set time to obtain a power generation power fluctuation component; according to the power generation power fluctuation component, a grid-connected point voltage fluctuation value is calculated; and according to energy storage characteristics of a battery and a super capacitor, each compensation frequency band is determined, the grid-connectedpoint voltage fluctuation value is used to determine the wavelet packet decomposition layer number, the secondary high frequency component and the highest frequency component in the photovoltaic power generation power signals are extracted as compensation power instruction values of the battery and the super capacitor, and power compensation is carried out. Compared with the prior art, the methodhas the advantages that the grid-connected point voltage fluctuation is reduced, the delay of stabilizing the target power is reduced, and the service life of the hybrid energy storage system is enhanced.

The invention relates to a universal fully-effective generating power machine belonging to generating power equipment which can fully and effectively convert conventional energy resources such as water energy, steam energy and the like and new energy resources such as wind energy, steam energy formed by solar heating, tidal water energy and the like into rotating mechanical energy. The machine mainly comprises one or a plurality of jet orifices, a regulating mechanism of the jet orifices, one or a plurality of universal fully-effective rotating wheels, a speed regulator and the like, wherein, the universal fully-effective rotating wheels correspond to the jet orifices and are arranged on a main shaft. The machine can fully develop and utilize water energy, steam energy and wind energy of all types, can fully and effectively convert the utilized water energy, steam energy and wind energy into rotating mechanical energy, can fully replace all current water turbines, steam turbines and wind turbines, and has the advantages of simple structure, reliable performance, low manufacturing cost and easy implementation. Thus, the universal fully-effective generating power machine can replace equipment of hydraulic, thermal and wind power generation industries, and can promote rapid development of new energy resource generating industries such as hydraulic fully-effective power generation, hydraulic wind power generation, solar steam power generation and the like to become main energy source power generating modes.

The invention discloses a wind-light power smoothing control method and system based on a hybrid energy storage system. The method includes the steps of acquiring the wind-light output power at a current moment, wherein the wind-light output power includes wind power output power and photovoltaic output power; according to the wind-light output power at the current moment, using a weighted movingaverage algorithm to calculate high-frequency power of the wind-light output power at the current moment; using a super capacitor for stabilizing the high-frequency power; according to the wind-lightoutput power at the current moment, using a low-pass filtering algorithm to calculate low-frequency power of the wind-light output power at the current moment; using a battery for stabilizing the low-frequency power. The method fully utilizes the advantages of large energy density of the battery and large power density of the super capacitor, so that power fluctuations in different frequency ranges are stabilized, and fluctuations of wind-light power are reduced to meet the requirements of grid connection.

The invention discloses a grid-connected inverter control method combining SVPWM with a sliding mode variable structure. The method comprises the following steps: A: establishing a two-level grid-connected inverter mathematical model, and obtaining a differential expression of output current of the inverter; B: deriving a corresponding state space equation based on the differential expression of the current, selecting d-axis and p-axis sliding modes output by an appropriate sliding mode inverter, and using the state space equation as a part of a sliding model current control objective function; and C: achieving current uncoupled control by current feedforward decoupling to reduce the corresponding control deviation. The grid-connected inverter control method disclosed by the invention hasthe advantages of having good dynamic steady state performance, being able to ensure relatively low switching frequency and completely meet the grid connection requirements, having good practicability, realizing the current uncoupled control by the current feedforward decoupling to reduce the corresponding control deviation, and having high tracking precision, low switching loss and easy digitization, etc.

The invention provides a through-type traction power supply system, relating to the technical field of traction power supply. A master transformer station CS<M> comprises a step-down transformer T0, the secondary side of which has more than one winding, and a super compensation system, the secondary side of which has more than one winding; the master transformer station CS<M> is used as a voltagesource, other transformer stations with a step-down transformer and a three phase-single phase cascaded converter N are used as system current sources, wherein the master transformer station CS<M> provides power through a three phase-single phase traction transformer TM, the structure of three phase input and single phase output is adopted, the primary side of the step-down transformer T0 is connected with a three phase power grid, the secondary side has more than one group of winding, three phases of output of the more than one group of winding are separately connected with a reactor in series and then are connected with an input end of corresponding super compensator SCN so as to form a parallel super compensation system SC; and the input end of a master controller MC is connected with athree phase network current, a three phase power grid voltage and a support capacitor voltage of the super compensator separately, and the output end of the master controller MC is connected with thecontrol end of the super compensation system SC.

The invention discloses a photovoltaic hybrid energy storage control method considering compensation prediction error and stabilization fluctuation. The method comprises the following steps: comparing photovoltaic output actual active power Ppv (t) with an output photovoltaic prediction error allowable range E, carrying out the grid connection when a grid connection requirement is satisfied, or carrying out the compensation prediction error primary control and the stabilization fluctuation secondary control, and then carrying out the grid connection. According to the method, the hybrid energy storage is utilized to realize the hierarchical control of compensating the prediction error and stabilizing the fluctuation, so that the hybrid energy storage system is clear in division of labor, the energy storage system is prevented from being overcharged and overdischarged, the energy storage capacity configuration is reduced, the economy is optimal, the effects of compensating the prediction error and stabilizing the fluctuation are achieved, and the grid-connected requirement is met; and the uncertainty, volatility and randomness of large-scale photovoltaic grid connection can be effectively reduced, and the electric energy quality and stability of a power grid are improved.

A power decoupling circuit for alternating current side coupling comprises an inductor, main switching devices, parasitic diodes and a decoupling capacitor, wherein the main switching devices are seven switching tubes, and each switching tube is connected with one parasitic diode in inverse parallel. The power decoupling circuit comprises four work modes, including a PHC charging mode, a PHC discharging mode, an NHC charging mode and an NHC discharging mode. An input end of the power decoupling circuit is connected with an output side of an inverter in parallel, the voltage amplitude on the output side of the inverter is high and has positive and negative periodic variation, so that the decoupling capacitor in the decoupling circuit designed on the basis of boost and buck circuits can acquire higher average voltage and larger voltage variation range, the capacitance of the decoupling capacitor is greatly reduced, the polarity of the decoupling capacitor is fixed, the grid connection requirement of the inverter can be met without a large electrolytic capacitor, the system size and cost are greatly reduced, and thus the service life of a photovoltaic generation system is substantially prolonged.

The invention discloses a stator permanent magnetic dual-rotor wind power generation system. The stator permanent magnetic dual-rotor wind power generation system comprises a direct-driven wind-power system; one end of the direct-driven wind-power system is connected with a wind machine, and the other end of the direct-driven wind-power system is connected with a diode uncontrolled rectifier and a DC-DC convertor; the other end of the DC-DC convertor is connected with an inverter; and the other end of the inverter is connected with a load. The stator permanent magnetic dual-rotor wind power generation system provided by the invention is an intellectualized, modularized and mechanized device; a Z-source inverter is adopted by the inverter, so by controlling a shoot-through duty ratio, a boost function similar to a two-stage power adjustment system is implemented very easily, and thus the input voltage grade as well as the power grade of the inverter can be reduced; as a stator permanent magnetic dual-rotor motor is adopted by the direct-driven wind-power system, the advantages such as the power density is high, the structure of a middle rotor is simple and the mechanical strength is high are achieved; and the stability of a DC-bus voltage of the wind-power system is maintained by the DC-DC converter by controlling a charging-discharging power of a super-capacitor, so the voltage stability of the wind-power system in large signal disturbance is implemented.

The invention provides a three-level inverter modulation mode switching method and device, equipment and a storage medium. The method comprises the following steps: acquiring a three-phase sinusoidal modulation wave; determining a first zero-sequence voltage component according to the three-phase voltage of the three-phase sinusoidal modulation wave, and superposing the three-phase sinusoidal modulation wave with the first zero-sequence voltage component to obtain a three-phase saddle-type modulation wave; determining a second zero-sequence voltage component according to the three-phase voltage of the three-phase saddle-type modulation wave, superposing the three-phase saddle-type modulation wave with the second zero-sequence voltage component, and performing adjustment according to a preset zero-sequence voltage adjustment factor to obtain a hybrid modulation smooth switching modulation wave; comparing the hybrid modulation smooth switching modulation wave with a preset triangular wave stacked in an inverted manner to generate a pulse width modulation signal; according to the invention, smooth switching of continuous and intermittent modulation modes is realized, the common-mode voltage and the common-mode current change stably in the switching process, and the new energy grid connection requirement is met.

The present invention provides a harmonic current suppression method of a single phase inverter. The method analyzes the effect caused by dead zone(s) on the basis of analyzing basic vector control ofthe single phase inverter, and by adopting an improved repetitive controller algorithm, harmonic current(s) caused by the dead zone(s) or power grid harmonic(s) are effectively suppressed, so that the single phase inverter has a very high output current quality, and thus the grid-connection requirements are satisfied.

The invention discloses a wind power plant grid-connected power smoothing method for optimizing charging and discharging of a double-battery system. According to the method, on the basis of wind powerultra-short-term prediction, an average wind power prediction value in a control period T is used as basic reference output power of a wind power plant, and the basic reference output power of the wind power plant in each control period T is dynamically corrected according to the charging and discharging energy imbalance degree of the double-battery system; when the dischargeable energy of the double-battery system is greater than the chargeable energy, the double-battery system is enabled to be charged less and discharged more by adjusting the basic reference output power of the wind power plant; on the contrary, when the rechargeable energy is greater than the dischargeable energy, the double-battery system is made to be discharged less and charged more, and therefore the difference ofthe charging and discharging energy of the double-battery system is reduced. According to the method, the output power of the wind power plant can meet the scheduling and grid connection requirements,meanwhile, the charge-discharge energy imbalance of the double-battery system is improved, the charge-discharge depth of each battery pack is optimized, the long-term stable operation of the system is ensured, and the method is simple, effective and convenient for practical engineering application.

The invention provides a rapid active power control method and system for a wind power plant. The method comprises the steps of adjusting the active output of a wind turbine generator through a wind power plant AGC system and an energy management platform according to a power grid dispatching instruction and the in-station measurement information of the wind power plant, and achieving the active control of a grid-connected point of the wind power plant so as to meet the grid-connected requirements of the power plant. The system collects in-station measurement information of the wind power plant, especially voltage and current information of the grid-connected point, and calculates real-time active power of the grid-connected point. A difference value is obtained between a power grid dispatching given active power value and actually measured active power, and then the difference value is superposed on the power grid dispatching instruction and is output to the wind power plant AGC system and the energy management platform, so that closed-loop regulation of the active power of the grid-connected point is realized, and the purpose of quickly and accurately regulating the active power of the wind power plant is achieved. The system avoids the defects of large manual adjustment error, slow response and the like of the wind power plant, and can automatically compensate the network loss of the wind power plant, so that the active power of the grid-connected point automatically follows the scheduling instruction.

The invention relates to a hybrid energy storage power control method for stabilizing photovoltaic power fluctuation. The method comprises the following steps: wavelet packet decomposition is carriedout on photovoltaic power generation power signals in a set time to obtain a power generation power fluctuation component; according to the power generation power fluctuation component, a grid-connected point voltage fluctuation value is calculated; and according to energy storage characteristics of a battery and a super capacitor, each compensation frequency band is determined, the grid-connectedpoint voltage fluctuation value is used to determine the wavelet packet decomposition layer number, the secondary high frequency component and the highest frequency component in the photovoltaic power generation power signals are extracted as compensation power instruction values of the battery and the super capacitor, and power compensation is carried out. Compared with the prior art, the methodhas the advantages that the grid-connected point voltage fluctuation is reduced, the delay of stabilizing the target power is reduced, and the service life of the hybrid energy storage system is enhanced.

The invention relates to a high-power intelligent harmonic and reactive current generating device based on an IGBT inverter, belonging to the field of power electronic technology. The device comprises a circuit breaker, a fuse, a high-pass filter, two reactors, a precharge circuit, an inverter, a power converter and a control circuit, wherein the circuit breaker is respectively connected with a test point of an electrical power system and the fuse; an output end of the fuse is respectively connected with the high-pass filter and an input end of the first reactor in parallel; an output end of the first reactor is sequentially connected with the precharge circuit, the second reactor and the inverter in series; a signal end of the control circuit is respectively connected with input ends of the first and the second reactors; an output end of the control circuit is connected with a control end of the inverter, and an input end thereof is connected with the power converter; and an input end of the power converter is connected with the test point of the electrical power system. The high-power intelligent harmonic and reactive current generating device adopts the IGBT to lead a three-phase alternating-current power supply to be rectified into a direct-current power supply, and controls the direct-current power supply to be inverted into the needed harmonic current by combining constant current loop algorithm.

The invention belongs to the technical field of wind power prediction, and specifically relates to a short-term wind power prediction system based on a covariance optimal combination model, including a data collection and storage module, a covariance optimal combination prediction module, a power prediction error analysis module, and a real-time communication module. The data acquisition and storage module sends the collected data required for wind power prediction and error analysis data to the covariance optimization combination prediction module and the power error analysis module to predict the wind power, and transmits the prediction results to the power prediction error analysis module, Then the forecast data is transmitted to the real-time communication module, and the real-time communication module transmits the forecast data to the dispatching center for service in real time. The system and method proposed by the present invention are simple and practical, the system used is efficient and convenient and has real-time communication and self-adjustment functions, and the accuracy of the prediction algorithm used is improved compared with a single physical model and statistical model, which is beneficial to wind power prediction develop.

The invention relates to a GSSA-based buck-type power converter dynamic model analysis method, comprising the following steps: (1) establishing a power converter system which comprises a three-phase balanced voltage source, a transmission line with the equivalent parameters of Req, Leq and Ceq, a three-phase 6-pulse controllable rectifier, a DC filter consisting of Ldc, Cdc and their respective equivalent series impedance rL, rC, and a buck-type step-down chopping link controlled by an IGBT; (2) using the DQ transformation theory to analyze the three-phase rectification link, using the GSSA method to respectively analyze the buck-type step-down chopping link, and establishing the model parameters of the power converter system; and (3) combining the thyristor and the IGBT chopping link under control of different trigger angles and duty ratios to analyze the response condition of the power converter system during the voltage fluctuation of the power supply, further proving the performance of the DQ and GSSA hybrid control model, and then according to the performance, selectively applying the model to electric vehicle charging stations, metal thermal processing, wind farm converter stations and inverter driving.

The invention relates to an inverter control method based on fuzzy PCI (Proportional Complex Integral) and PR (Proportional Resonance) parallel composite control. The inverter control method comprises the steps of S1, acquiring a current three-phase grid-connected current under a three-phase static coordinate system in real time; S2, acquiring a grid-connected current instruction under the three-phase static coordinate system to obtain an AC error signal under the three-phase static coordinate system; S3, acquiring a first current value under the three-phase static coordinate system after the AC error signal passes through a PR controller; S4, acquiring a second current value under the three-phase static coordinate system after the AC error signal passes through a PCI controller; and S5, acquiring a composite control current value under the three-phase static coordinate system after the first current value is added to the second current value, and inputting the composite control current value to a PWM (Pulse Width Modulation) module. Compared with the prior art, the inverter control method has the advantages that a coordinate conversion link can be omitted, the inverter control method can be directly applied to the three-phase static abc coordinate system, the control stability of a system is ensured, and the waveform quality, the tracking precision and the power factor of the grid-connected current are improved.

The invention relates to a grid-connected photovoltaic power generation system capable of stabilizing the quality of electric energy. The grid-connected photovoltaic power generation system comprises a power generation module and a grid-connected access box, wherein the power generation module comprises a fixed support and a solar cell panel arranged on the fixed support; the power generation module is connected with a direct-current motor for converting direct current generated by the power generation module into mechanical energy; the direct-current motor is connected with an alternating-current motor for converting the mechanical energy into alternating current; the alternating-current motor is connected with a transformer; and the transformer is connected with the grid-connected access box. The grid-connected photovoltaic power generation system has the advantages that the direct current generated by the power generation module is converted into the mechanical energy through the direct-current motor, then the mechanical energy is converted into the alternating current through the alternating-current motor, and the alternating current is converted into same-frequency and same-phase sinusoidal current with a power grid through the transformer, so that three-phase output balance for a three-phase alternating-current generator set is realized, the quality of the electric energy is stable, the system is free of harmonic generation, a synchronous connection requirement is met, and the operational safety performance of the grid-connected power generation system is improved.

The invention discloses a wave power generation unit comprising a wave power collection mechanism, an energy conversion mechanism, a generator, a converter, and a control system. The wave power collection mechanism, the energy conversion mechanism, the generator and the converter are disposed on a platform and connected in sequence. The control system is connected with every one of the wave power collection mechanism, the energy conversion mechanism, the generator and the converter. The energy conversion mechanism is provided with a speed regulating valve inside. The current output end of the converter is connected with a power grid. The wave power generation unit is characterized in that the wave power collection mechanism converts wave power into mechanical energy and transmits the mechanical energy to the energy conversion mechanism; the energy conversion mechanism converts the mechanical energy into rotational mechanical energy driving the generator to generate powder; the current output from the generator is converted into current, the same as the voltage and frequency of the power grid, by the converter, and the current can be connected to the power grid directly; the control system acquires status signals of all steps of the wave power generation unit, can control the energy conversion mechanism, the generator and the converter in a coordinated manner so as to control output power, and ensures output electricity of the wave power generation unit is satisfactory.