61 results about "Grid-connected photovoltaic power system" patented technology

A grid-connected photovoltaic electrical power system with both array level and string level remote monitoring and production and efficiency analysis capabilities. The inventive system includes an array level monitoring component, software for recording and analyzing data obtained through the array level monitoring component, and a string level monitoring component.

The invention discloses a harmonic wave damping control method for a one-phase LCL type grid-connected inverter. The harmonic wave damping control method for the one-phase LCL type grid-connected inverter mainly comprises a fundamental wave control loop, a harmonic wave damping loop and a capacitance current inner loop. The fundamental wave control loop enables fundamental wave components in non-error follow current command signals of network-entry currents to change, and grid connection with a high power factor is achieved. The harmonic wave damping loop can inhibit background harmonic voltage of a power grid and the influence on the network-entry currents of the grid-connected inverter from the harmonic wave components of the current command signals at the same time, and provide the network-entry currents with high quality. The capacitance current inner loop is used for improving system damping, inhibits the LCL resonance peak and improves the system stability. The harmonic wave damping control method is easy to achieve, and can improve the ability of the grid-connected inverter to inhibit the harmonic wave components in the background harmonic voltage of the power grid and the current command signals, and the quality of the network-entry currents of the grid-connected inverter is improved. The harmonic wave damping control method is suitable for a grid-connected photovoltaic power generation system, a fuel battery and a wind power generation grid-connected system of an LCL type filter.

The invention discloses a method for designing a hybrid damping parameter of an LCL filter in a photovoltaic grid-connected inverter, and belongs to the technical fields of new energy sources and distributed grid-connected generation. The method is characterized in that: the resonance of the LCL filter is suppressed by adopting an active damping/passive damping cooperative working method, whereina filter capacitive current feedback control method is adopted for an active damping part and the method of connecting filtering capacitance in series with damping resistance is adopted for a passivedamping part. For the LCL filter, the damping resistance required by passive damping and a feedback coefficient of active damping are computed under the condition of ensuring a sufficient damping coefficient, and a designed cooperative damping control scheme is checked to make the loss of the damping resistance as low as possible, avoid the influence of system control delay on damping running; and the damping is adapted to strong power grid access and the weak power grid access of remote areas. The method is applied to photovoltaic grid-connected generation systems adopting the LCL filter, fuel cells and grid-connected wind power generation systems.

The invention discloses an equivalent simulation method for a grid-connected photovoltaic power generation system. In the grid-connected photovoltaic power generation system, a direct current is converted into an alternating current with the same amplitude value, the same frequency and the same phase as those of a grid voltage by a photovoltaic array through an inverter, and the alternating current is connected with a power grid, so that the photovoltaic array which is operated normally is equivalent to a constant-current source. The mathematical model of a grid-connected power generation system is represented by the following third-order dynamic differential equations which are shown in the specification, and the active response P and the reaction response Q of the grid-connected photovoltaic power generation system are shown in the specification. By the equivalent simulation method of the grid-connected photovoltaic power generation system, the steady state and transient characteristics of the photovoltaic power generation system under a grid-connected operation condition can be simulated accurately; and the equivalent simulation method can serve as a research tool of the grid-connected photovoltaic power generation system.

The invention provides a solar air conditioner CCHP (Combined Cooling Heating and Power) system based on a photovoltaic power generation system. The solar air conditioner CCHP system comprises the grid-connected photovoltaic power generation system, a multifunctional central air conditioner all-in-one machine, a battery plate cooling device and a central controller. On the basis of the solar photovoltaic power generation system and an electric compression type multifunctional central air conditioner unit, solar photovoltaic power generation is utilized for driving the central air conditioner unit, so that functions of a common air conditioner, a heat pump type air conditioner, an air source heat pump water heater and cold-hot water energy conversion are simultaneously realized in the same unit; the battery plate cooling device is capable of reducing the temperature of a battery piece by virtue of a liquid cooling mode, so that the power generation efficiency is effectively improved. The solar air conditioner CCHP system provided by the invention can be used for not only overcoming the problems of single function and high energy consumption of a traditional air conditioner and an air energy heat pump water heater, also solving the problem of low energy utilization rate of a common solar air conditioner, and fully utilizing the solar energy and air energy, has functions of cooling, heating, obtaining domestic hot water and storing power, can be used for CCHP of solar energy and has the advantages of high efficiency, energy conservation and environmental friendliness.

The invention discloses a ground source heat pump coupling system based on photovoltaic photo-thermal effects. The ground source heat pump coupling system comprises a grid-connected photovoltaic power generation system, a solar photo-thermal system and a ground source heat pump system. On one hand, a PV/T heat collector 1 converts solar energy into electric energy, the electric energy is supplied to a machine room water pump and a ground source heat pump unit through a photovoltaic controller 2, an inverter 4 and an alternating-current power distribution cabinet 5, electricity can be stored in a storage battery 3 or sold in a public power grid when the electricity is rich, and the electricity can be supplemented by the storage battery 3 and the public power grid when the electricity is insufficient; and on the other hand, after the heat converted by the PV/T heat collector 1 is transmitted to a heat storage water tank 6, the heat is used for supplying hot water through a first heat exchanger 7, when the heat is rich, the heat can be stored in an underground heat storage pipe 15 through a second heat exchanger 16 and used for heating of the ground source heat pump in winter, and when the heat is insufficient, the ground source heat pump can supplement the heat. Compared with a traditional water chilling unit, coal power generation and other modes, the operation cost is reduced, and economic benefits are remarkable, energy consumption and CO<2> emission are reduced, and the national policies of peak carbon dioxide emissions and carbon neutrality are actively responded.

The invention discloses an inverse-excitation type single-stage inverter used in an interconnected photovoltaic power generation system, including an input side circuit, an inverse-excitation transformer and an outlet side circuit, wherein, the input side circuit includes a photovoltaic array, a first filtering capacitance and a first power switch tube, which are connected to the primary side of the transformer; and the outlet side circuit includes a second to fifth power switch tube and a second filtering capacitance, which are connected to the secondary side of the transformer. The invention has the following advantages that the single-stage structure not only realizes voltage boosting inversion output, but also reduces the size, volume weight and cost of the complete machine; high-frequency electric insulation is realized; the entire circuit has no other magnetic components except the high-frequency inverse-excitation transformer, the entire circuit uses less power devices with simple structure and small spending; and the control scheme is more simple and is easy of implementing.

A grid-connected photovoltaic power system in-loop real-time simulation platform based on a virtual synchronizer comprises three portions consisting of an upper computer, a PXI real-time simulation system and an external measurement controller. The upper computer is connected with the PXI real-time simulation system and the external measurement controller through an Ethernet, and the PXI real-timesimulation system is connected with the external measurement controller through an I/O interface. The grid-connected photovoltaic power system in-loop real-time simulation platform based on the virtual synchronizer can rapidly develop and verify a control strategy in a laboratory environment, can simulate operation features of a photovoltaic array and can allow the controller to achieve comprehensive closed-loop verification prior to actual condition test so as to greatly save the test cost, shorten the development period, improve the operation safety and provide a basic research platform forthe virtual synchronizer control technology research and development and the optimization control of the grid-connected photovoltaic power system.

The invention relates to the field of the quality evaluation of steady state electric energy and provides a comprehensive evaluation method for the quality of the steady state electric energy so as to perform the relatively intuitive and comprehensive evaluation on the electric energy quality of a point of common coupling (PCC) of a grid-connected photovoltaic system. The method specifically comprises the following steps: (1) integrating subjective and objective weights by adopting a combination weighting method, namely a maximum deviation method, and obtaining an integrated weight vector; (2) by adopting a main-element projection method, transforming each evaluated data group from a multidimensional manner to a one-dimensional manner by utilizing an ideal decision vector designed by each main element; and (3) performing grade interval partition, namely dividing value limiting provisions in national standard into multiple grades according to a certain standard, and determining the electric energy quality condition of data of measuring points by determining grade intervals in which data to be evaluated are positioned. The method is mainly applied to evaluating the quality of the steady state electric energy.

The invention relates to a grid-connected photovoltaic power generation system, in particular to a miniature grid-connected inverter anti-islanding method based on group control disturbance. The miniature grid-connected inverter anti-islanding method based on group control disturbance is characterized in that the method is based on a hardware component of the traditional miniature grid-connected inverter; a plurality of photovoltaic modules are combined to a bus of a grid-connected photovoltaic power generation system; each photovoltaic module is provided with a miniature grid-connected inverter; each miniature grid-connected inverter has a power line carrier communication function; a group control synchronizing technology is used in the anti-islanding method; and anti-islanding protection is performed after detection, disturbance and monitoring. Passive anti-islanding monitoring is taken as a main measure; active disturbance is taken as an auxiliary measure; the problem that disturbance fails due to the fact that the capacity of a single miniature grid-connected inverter is low and the power of the single miniature grid-connected inverter which independently performs disturbance anti-islanding in a power grid system is small is solved by a mode that quantitative changes cause a qualitative change; monitoring is based on the original equipment of the miniature grid-connected inverters; and other hardware is not required.

The invention provides a power transmission method and system for realizing real-time tracking internal resistance matching. The method comprises the steps: carrying out modeling and selection on a Boost circuit boosting module of a two-stage three-phase grid-connected photovoltaic power generation system, and obtaining an equivalent model and a simplified equivalent model of an inverter DC side for an inverter circuit; defining photovoltaic cell internal resistance RST, equivalent input resistance ROUT of the inverter input side and duty ratio DST of a photovoltaic inverter under a standard condition, and calculating photovoltaic cell internal resistance variation delta R1, which changes with the outside world, and duty ratio delta D, which is adjusted with the change of the delta R1; andby changing the delta D, finding real-time match with the photovoltaic cell internal resistance delta R, and realizing photovoltaic power generation maximum power tracking. On the basis of the methodprovided by the invention, the invention further provides the power transmission system for realizing real-time tracking internal resistance matching. On the premise of ensuring tracking accuracy andstability, the method and system realize simplicity and rapidity of a power transmission algorithm for realizing real-time tracking internal resistance matching.

The invention relates to the field of grid-connected photovoltaic power generation performance testing, in particular to a current harmonic index quantification assessment method of a grid-connected photovoltaic power generation system. The current harmonic index quantification assessment method is characterized by including the following steps: (1) performing interval statistics on irradiation intensity; (2) performing statistic analyzing on the timed sampling daytime actually measured irradiation intensity according to the intervals; (3) performing sampling and recording on voltage and amperage of the photovoltaic power generation system on the grid-connection points of the photovoltaic power generation system; (4) determining the measured current harmonic weight coefficients corresponding to the different irradiation intensity; (5) obtaining the harmonic current average value under different irradiation conditions; and (6) calculating the weighting current harmonic value according to the current harmonic weight coefficients of the irradiation intensity intervals. By means of the current harmonics index quantification assessment method, under the condition that the current harmonics of the grid-connected photovoltaic power generation system accord with the standard limiting value requirements, the comprehensive current harmonics of the grid-connected photovoltaic power generation system are obtained in weighting mode when the irradiation intensity changes, and accordingly assessment on performance of the photovoltaic power generation system can be achieved.

The invention discloses a comprehensive quality evaluation technology for a grid-connected photovoltaic (PV) power generation system. The evaluation process includes the following steps: the total solar irradiation H incident on a PV array surface of the grid-connected PV power generation system is measured and calculated; the total solar irradiation energy E received by the grid-connected PV power generation system is calculated based on the area A of PV modules applied in the grid-connected PV power generation system, the number N of the applied modules, and the module declared efficiency [mu]STC, and the theoretical gross generation WDC (direct current) of the grid-connected PV power generation system is further obtained; monitoring statistics of the gross generation WAC (alternate current) of the grid-connected side of the grid-connected PV power generation system is carried out; the comprehensive quality evaluation coefficient of the grid-connected PV power generation system is calculated based on a formula, i.e. comprehensive quality evaluation coefficient R=actual gross generation WAC of the grid-connected PV power generation system/theoretical gross generation WDC of the grid-connected PV power generation system*100%. The comprehensive quality evaluation technology for the grid-connected PV power generation system has the advantage of easiness in calculation and operation as well as high practicability, thereby achieving the worthiness for wide popularization.

The invention discloses an islanding detection method for a photovoltaic energy storage system. A grid-connected photovoltaic power generation system comprises a photovoltaic module and an inverter, wherein the photovoltaic module is connected to a public supply network through the inverter and a breaker; a local load is connected to a point of common coupling between the inverter and the breaker; the islanding detection method is characterized in that when the power grid is disconnected, if the active power and the reactive power are matched, and the condition that (1-U2/U0) is smaller than PG/PL smaller than (1-U1/U0) is satisfied, the islanding detection is not conducted. The islanding detection method disclosed by the invention has the advantages that the method can reliably and accurately detect the islanding, increase the strain capacity of the equipment, and avoid misjudgment.

The present invention relates to a method for measuring the frequency of phasor of a power system, belonging to the technical field of power systems and automation thereof. A grid-connected photovoltaic generation system is provided with a control module, a data buffer module, an inverter, a sampling module and an analog-to-digital conversion module; a voltage transformer is connected to the grid side of the grid-connected photovoltaic generation system; the voltage transformer is electrically connected to the analog-to-digital conversion module; the analog-to-digital conversion module converts an analog signal sent by the voltage transformer into a digital signal; the sampling module samples the digital signal and transmits the digital signal into the data buffer module; the data buffer module is provided with a plurality of data windows; and the control module receives signals from the data windows.

The invention discloses a comprehensive island detection method of a photovoltaic energy storage system. A grid-connected photovoltaic power generation system is composed of a photovoltaic module and a converter. The photovoltaic module is connected to a public supply system through the converter and a breaker, a local load is connected on a public coupling point between the converter and the breaker, current which is slightly distorted is injected into a power grid in the detection process, and therefore a continuous frequency changing tendency is formed. The comprehensive island detection method comprises passive detection and active detection, is simple and reliable, and improves detection efficiency.

A grid-connected photovoltaic generation system taking regard of cloud shielding comprises a control module and an electrical module. The control module is connected with and is configured to control the electrical module; the electrical module is composed of a photovoltaic array, a switch matrix, a DC/DC converter, a grid-connected inverter and a transformer; the control module is the configuration control algorithm; the photovoltaic array is composed of a plurality of photovoltaic modules; the photovoltaic modules are connected with the switch matrix, the switch matrix is connected with the DC/DC converter, the DC/DC converter is connected with the grid-connected inverter, the grid-connected inverter is connected with the transformer, and the transformer is connected with the power grid; the power grid is connected with the grid-connected inverter and the DC/DC converter through an inverter control circuit; the switch matrix is connected with the DC/DC converter through an MPPT solar energy controller; the configuration control algorithm is connected with a plurality of photovoltaic modules; and the control module is connected with the switch matrix through the switch matrix driving circuit. The grid-connected photovoltaic generation system taking regard of the cloud shielding improves the disadvantage of the cloud shielding problem of a traditional photovoltaic power generation system to allow the photovoltaic generation system to keep stable and efficient output in the condition of cloud shielding.

The invention provides a control method for a high-quality DC (direct current)/AC (alternating current) converter of a grid-connected photovoltaic power system, belongs to the grid-connected photovoltaic power technology, and aims to develop a high-quality DC/AC converter suitable for grid-connected operation. The control method is characterized in that a phase-shifting transformer grid connection mode is adopted, current distribution and control are performed on three-phase bridge inverters (3 and 4) according to specific conversion laws of the formula (1) and the formula (2), thyristor controllability is realized, a multi-level synthetic technology adopting equal-increment step-shaped triangular-wave current waveform is adopted, a current waveform similar to a sine wave is obtained at an output side of the phase-shifting transformer, the functions of low harmonic control, lead-lag continuous adjustment of a power factor and free regulation of direct current in the range ranging from 0 to a rated value are realized, and the method is applied to grid-connected photovoltaic power systems with various capacities.