CN112360731A - Multi-machine parallel photovoltaic equipment control system and optimization method - Google Patents

Multi-machine parallel photovoltaic equipment control system and optimization method Download PDF

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Publication number
CN112360731A
CN112360731A CN202011077829.3A CN202011077829A CN112360731A CN 112360731 A CN112360731 A CN 112360731A CN 202011077829 A CN202011077829 A CN 202011077829A CN 112360731 A CN112360731 A CN 112360731A
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water pump
load
module
parallel
power
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江友华
叶怀宇
张国旗
朱沁琳
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Shenzhen Third Generation Semiconductor Research Institute
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Shenzhen Third Generation Semiconductor Research Institute
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/06—Control using electricity
    • F04B49/065—Control using electricity and making use of computers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B17/00—Pumps characterised by combination with, or adaptation to, specific driving engines or motors
    • F04B17/006—Solar operated
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B17/00—Pumps characterised by combination with, or adaptation to, specific driving engines or motors
    • F04B17/03—Pumps characterised by combination with, or adaptation to, specific driving engines or motors driven by electric motors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B23/00—Pumping installations or systems
    • F04B23/04—Combinations of two or more pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/007—Installations or systems with two or more pumps or pump cylinders, wherein the flow-path through the stages can be changed, e.g. from series to parallel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/02—Stopping, starting, unloading or idling control
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/14—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by switching loads on to, or off from, network, e.g. progressively balanced loading
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/466—Scheduling the operation of the generators, e.g. connecting or disconnecting generators to meet a given demand
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/30—Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
    • Y02B70/3225—Demand response systems, e.g. load shedding, peak shaving
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S20/00—Management or operation of end-user stationary applications or the last stages of power distribution; Controlling, monitoring or operating thereof
    • Y04S20/20—End-user application control systems
    • Y04S20/222—Demand response systems, e.g. load shedding, peak shaving

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Computer Hardware Design (AREA)
  • Photovoltaic Devices (AREA)

Abstract

The invention relates to the field of photovoltaic equipment control systems, and provides a multi-machine parallel photovoltaic equipment control system and an optimization method. The system comprises: a photovoltaic array for generating electricity; the equipment module comprises a plurality of parallel equipment units, wherein each equipment unit comprises a frequency conversion subunit, an electric subunit and a water outlet subunit; the load partition module is used for enabling each load partition to correspond to each equipment unit one by one; a power output module connected to the photovoltaic array to output a stable direct current to the equipment module; the control module is used for generating a control signal according to the output power of the power output module and the load partition data and transmitting the control signal to the equipment module; the control signal controls the number of the parallel equipment units which are put into operation and adjusts the input power of each parallel equipment unit which is put into operation to correspond to the load priority level one by one. The invention effectively solves the bottleneck technical problems that the matching degree of the photovoltaic array and the load is lower, the solar energy cannot be fully utilized and the like.

Description

Multi-machine parallel photovoltaic equipment control system and optimization method
Technical Field
The invention relates to the field of photovoltaic equipment control systems, in particular to a multi-machine parallel photovoltaic equipment control system and an optimization method.
Background
The photovoltaic water pump is directly driven by solar energy, has very obvious energy-saving and environment-friendly benefits, does not consume conventional energy, has the advantages of no noise, full automation, high reliability, good adaptability of water supply and evaporation capacity, obvious economy and the like compared with a diesel engine water pump, can solve the problems of drinking water and agricultural irrigation in remote areas for remote mountainous areas with sufficient underground water sources but unavailable power grids, and has important significance in aspects of economy, society, environment and the like.
While the development of independently operating individual photovoltaic plant control systems has achieved significant success, a number of key issues remain. For a single system, when the photovoltaic array is separately connected with the high-capacity motor-water pump, under the condition of weak illumination intensity, such as early morning and evening, the output power of the photovoltaic array cannot meet the water pumping threshold of the water pump, so that the system cannot meet the load requirement, and the resource waste is caused. On the other hand, when the illumination intensity is strong, such as at noon on a sunny day, the output power of the photovoltaic array is large and far exceeds the rated power of a single motor-water pump, so that the excess energy cannot be utilized. Therefore, when the output power of the photovoltaic array continuously changes along with the conditions of time, weather, temperature and the like, the matching degree of the photovoltaic array and the load of the photovoltaic equipment control system operated by a single machine is low, and the solar energy cannot be fully utilized.
Disclosure of Invention
The invention provides a multi-machine parallel photovoltaic equipment control system aiming at the problems that the matching degree of a photovoltaic array and a load is lower and solar energy cannot be fully utilized in the existing single-machine operation photovoltaic equipment control system, which comprises:
a photovoltaic array for generating electricity;
the water pump module comprises a plurality of water pump units connected in parallel, wherein each water pump unit comprises a frequency conversion subunit, an electric subunit and a water outlet subunit;
the load partitioning module is provided with load priority data for partitioning the load priority according to the load size and corresponding load size data; each load partition corresponds to each water pump unit one by one;
the power output module is connected with the photovoltaic array to output stable direct current to the water pump module;
the control module is used for generating a control signal according to the output power and the load priority data of the power output module and the corresponding load size data and transmitting the control signal to the water pump module;
the control signal controls the subareas with high load priority levels to be put into the water pumps to operate firstly so as to determine the number of the parallel water pump units which are put into operation;
and the control signal adjusts the input power of each parallel water pump unit which is put into operation to correspond to the load priority level one by one.
Preferably, each load partition of the load partition module comprises a plurality of sub-partitions; each sub-partition is provided with a humidity sensor.
Preferably, the load priority zone information includes humidity information, and the humidity sensor feeds back the humidity data to the control module to generate a corresponding control signal.
Preferably, the control module includes:
the control module includes:
the model establishing submodule is used for establishing a mathematical model of the output power of the photovoltaic array;
the obtaining submodule is used for obtaining the output power data of the power output module, the load priority data of the load partitioning module and the corresponding load size data based on the first model establishing submodule;
the processing submodule is used for processing the output power data acquired by the acquisition submodule;
the determining submodule is used for determining the number of the parallel water pump units which are put into operation according to the load priority data;
and the control submodule is used for controlling the subarea with high load priority level to be firstly put into water pump operation and controlling the input power of each parallel water pump unit to be put into operation to be in one-to-one correspondence with the load priority level according to the output power data processed by the processing submodule, the load priority level data and the corresponding load size data of the load subarea module and the number of the parallel water pump units put into operation.
An output power mathematical model is established based on the photovoltaic array to calculate the output power, and when the input power of the photovoltaic array cannot meet the starting operation condition of the water pumps of all the parallel subunits, a load area needing preferential water supply is started first, so that the water supply utilization rate and the economic efficiency are improved.
Preferably, the control module is electrically connected with the water pump module; and each water pump unit is electrically connected with the photovoltaic array and the power output module respectively.
Preferably, the control module is electrically connected with the frequency conversion subunit of the water pump module to adjust the input power of each parallel water pump unit which is put into operation to correspond to the priority level of the load one by one.
Preferably, the electric subunit of each water pump unit is connected with the frequency conversion subunit and the water outlet subunit of the water pump unit; the frequency conversion subunit is connected with the photovoltaic array and the power output module.
Preferably, the frequency conversion subunit comprises a frequency converter; the electrical subunit comprises an electrical motor; the water outlet subunit comprises a water pump.
Based on the same inventive concept, the invention further provides an optimization method of the photovoltaic equipment control system, which comprises the following steps:
connecting the photovoltaic array with a water pump module formed by connecting a plurality of water pump units in parallel through a power output module;
carrying out load priority zoning, wherein the zoning comprises load priority data and corresponding load size data for carrying out the load priority zoning according to the load size, and each load zoning corresponds to each water pump unit one by one;
adjusting the number of water pump units put into operation according to the output power of the power output module and the load priority data;
and controlling the subarea with high load priority to be put into the water pump to operate firstly according to the load priority data and the corresponding load size data, wherein the output power of each water pump unit put into operation corresponds to the load size.
Preferably, the connecting the photovoltaic array with the water pump module formed by connecting the power output module and the plurality of water pump units in parallel further comprises: an output power mathematical model is established based on the photovoltaic array to calculate the output power.
Has the advantages that: the invention connects a plurality of small-capacity motor-water pump units in parallel, and adjusts the running state among the units in real time through communication. Under the condition of weak illumination intensity, the output power of the photovoltaic array is small, but the output power of the photovoltaic array is enough to drive a single small-capacity motor-water pump unit, so that priority water supply can be performed on important loads, other units are put into operation successively along with the continuous increase of the output power of the photovoltaic array, and the flow rate of each unit water pump is continuously adjusted according to the change of the output power of the photovoltaic array, so that the energy is reasonably utilized, the matching degree of the photovoltaic array and the loads is improved, and the system efficiency is improved.
Drawings
Fig. 1 is a schematic view of a control system for a photovoltaic device with multiple parallel units according to embodiment 1 of the present invention;
fig. 2 is a structural diagram of a control system of a multi-parallel photovoltaic device according to embodiment 3 of the present invention;
fig. 3 is a graph showing the change of the flow rate of the water pump according to the number of the water pumps and the input power provided by embodiment 3 of the present invention;
fig. 4 is a graph of the change of the system load shortage rate with the number of water pumps and the input power provided by embodiment 3 of the present invention;
fig. 5 is a graph showing a relationship between the number of parallel water pump units and input power according to embodiment 3 of the present invention.
Fig. 6 is a structural diagram of a control module 50 of a multi-parallel photovoltaic device control system according to embodiment 1 of the present invention.
Fig. 7 is a method for optimizing a control system of a photovoltaic device connected in parallel by multiple units according to embodiment 2 of the present invention.
Detailed Description
Specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention may be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Embodiment 1 this embodiment provides a multimachine parallelly connected photovoltaic equipment control system
As shown in fig. 1, a schematic diagram of a control system for multiple parallel photovoltaic devices provided in this embodiment includes:
a photovoltaic array 10 for generating electricity;
the water pump module 20 comprises a plurality of water pump units connected in parallel, wherein each water pump unit at least comprises a frequency conversion subunit, an electric subunit and a water outlet subunit;
a load partitioning module 30, which is provided with load priority data and corresponding load size data for partitioning the load priority according to the load size; each load partition corresponds to each water pump unit one by one;
a power output module 40 connected to the photovoltaic array to output a stable direct current to the water pump module;
the control module 50 is used for generating a control signal according to the output power and the load priority data of the power output module and the corresponding load size data and transmitting the control signal to the water pump module;
the control signal controls the subarea with high load priority level to be put into the water pump to operate firstly so as to determine the number of the parallel water pump units which are put into operation;
the control signal adjusts the input power of each parallel water pump unit which is put into operation to correspond to the load priority level one by one.
Each load partition of the load partition module comprises a plurality of sub-partitions; each sub-partition is provided with a humidity sensor. The load priority zone information includes humidity information, and the humidity sensor feeds back the humidity data to the control module to generate a corresponding control signal.
Preferably, as shown in fig. 6, the control module 50 is a structural diagram of the control module 50, and includes:
the model establishing submodule 501 is used for establishing a mathematical model of the output power of the photovoltaic array;
an obtaining submodule 502, which obtains the output power data of the power output module, the load priority data of the load partition module and the corresponding load size data based on the first model establishing submodule;
a processing submodule 503, configured to process the output power data acquired by the acquisition submodule;
a determining submodule 504, configured to determine, according to the load priority data, the number of parallel water pump units that are put into operation;
and the control submodule 505 is configured to control, according to the output power data processed by the processing submodule, the load priority data and the corresponding load size data of the load partition module, and the number of the parallel water pump units put into operation, a partition with a high load priority level to be put into water pump operation first, and input power of each parallel water pump unit put into operation to correspond to the load priority level one by one.
An output power mathematical model is established based on the photovoltaic array to calculate the output power, and when the input power of the photovoltaic array cannot meet the starting operation condition of the water pumps of all the parallel subunits, a load area needing preferential water supply is started first, so that the water supply utilization rate and the economic efficiency are improved.
The control module is electrically connected with the water pump module; and each water pump unit is electrically connected with the photovoltaic array and the power output module respectively. The control module is electrically connected with the frequency conversion subunits of the water pump module so as to regulate the input power of each parallel water pump unit which is put into operation to correspond to the load priority level one by one. The electric subunit of each water pump unit is connected with the frequency conversion subunit and the water outlet subunit of the water pump unit; the frequency conversion subunit is connected with the photovoltaic array and the power output module. The frequency conversion subunit comprises a frequency converter; the electrical subunit comprises an electrical motor; the water outlet subunit comprises a water pump.
Taking an irrigation scene as an example, a load area is an irrigation area, each irrigation area corresponds to each water pump unit, irrigation priority data of the irrigation area is loaded into a central controller in advance, the same irrigation area is divided into a plurality of annular sub-areas, each annular sub-area is provided with a humidity sensor, the inner ring is assumed to be easier to be dry than the outer ring, the humidity sensor feeds humidity information back to the central controller (namely a control module) and compares the humidity information with a humidity threshold value arranged in the central controller so as to judge whether irrigation is needed, if the humidity of a certain inner ring is lower than the threshold value, and the humidity of other rings in the irrigation area is higher than the threshold value, irrigation is only needed in the inner ring, the specific area of each irrigation area needing irrigation can be judged according to the comparison between the humidity feedback information and the threshold value, the central controller outputs analog signals or digital signals to be electrically connected with frequency converters of each water pump unit, and controlling the actual input power of each water pump unit to determine the water supply amount of the water pump, so as to realize accurate irrigation.
In order to research a multi-machine parallel photovoltaic equipment control system, a mathematical model is established for a photovoltaic array from the angle of the output power of the photovoltaic array, and the net photovoltaic power generated by the photovoltaic array is expressed as follows:
Figure BDA0002717330440000061
wherein I (t) is the irradiance in W/m at the tilted collector plane2；ISTCIrradiance under a standard state is generally 1000W/m2(ii) a PP is photovoltaic array production under standard conditionsMaximum power in units of W; beta is the attenuation coefficient of the performance of the photovoltaic array after the temperature of the cell rises, and for the silicon photocell, the value is 0.004/DEG C; t iscellIs the temperature of the cells in the array; t isSTCIs the temperature of the battery in the standard state (25 ℃); i ismIs the lower limit value of the irradiance of the photovoltaic array, and when the irradiance is lower than the lower limit value, the photovoltaic array is considered to be incapable of outputting power, ImThe value of (d) is determined by:
Figure BDA0002717330440000071
wherein, PPV,minIs the minimum value of the available photovoltaic power. At the same time, TcellThe value of (d) can be estimated as:
Tcell＝Ta+S·I(t) (3)
wherein, TaIs the ambient temperature; s is the array plate tilt coefficient, which for a silicon photocell is 0.03 ℃/(Wm)-2). Irradiance i (t) is estimated as a function of time:
Figure BDA0002717330440000072
wherein θ is the angle of incidence of the sun with respect to the inclined photovoltaic panel plane; thetazIs the angle of incidence of the sun with respect to the horizontal plane; i isb(t) is the direct solar irradiance versus time in W/m2；Id(t) is the solar diffuse irradiance versus time in W/m2(ii) a Psi is the tilt angle of the photovoltaic array, taken at 50 °; ρ is the reflectance, and is taken to be 0.2. And substituting the formula (2-4) into the formula (1) to obtain the output power of the photovoltaic array. The total power theoretically obtained by the water pump can be estimated as:
P＝ηm·ηinv·PPV (5)
wherein eta isinvIs the efficiency of the inverter; etamIs the efficiency of the motor.
In order to determine the flow of the water pump unit, a mathematical model is established for the water pump. When the water pump provides the water yield with the flow rate of Q, the corresponding total lift H is as follows:
H＝Δz+(Rs+K)·Q2 (6)
wherein Δ z represents the height change from the water source to the irrigation system, with a constant value; rsIs the equivalent resistivity of the irrigation system (including pipe losses and height losses); k is the total flow coefficient of the spray head; q is the total flow of the water pump control system. The ratio of the lift of the water pump at the maximum rotating speed to the lift of the water pump at any rotating speed is as follows:
Figure BDA0002717330440000081
wherein HMAnd QMThe maximum system lift and the maximum flow rate correspond to the maximum rotating speed of the water pump; hiAnd QiIs the corresponding lift and flow at any rotational speed. Since the constant Δ z is negligible compared to the two terms related to the flow, the operating curves of the water pump at different rotational speeds approximately follow the equivalent curve obtained by the water pump similarity theorem, from which it can be derived:
Figure BDA0002717330440000082
wherein Q isi,PiRespectively the system flow when the rotating speed of the water pump is i and the active power input into the water pump; pMIs rated active power, Q, of the water pumpMIs the maximum flow of the water pump. Corresponding lift (H) of general water pump at maximum speedM) Flow rate (Q)M) And rated power (P)M) Is a known value.
Preferably, the control module is connected with the water pump module through a bus; and each water pump unit is respectively connected with the photovoltaic array and the power output module.
The system configures the optimal input power of the frequency converter of the water pump unit according to the area size of an irrigation area and the actual required flow (namely the lift) of the water pump, so that the system can ensure that a single water pump unit can be driven under the condition of weak illumination intensity, and can preferentially supply water to loads with high priority, such as the drought field with severe priority. The defect that a photovoltaic equipment control system running in a single machine or a plurality of parallel water pumps which are unreasonably configured cannot be started under the condition of low input power due to overhigh pumping threshold is overcome, the waste of solar energy is avoided, and the energy utilization rate is high.
Embodiment 2 this embodiment provides a multi-machine parallel photovoltaic device control system optimization method
As shown in fig. 7, the method includes:
s1, connecting the photovoltaic array with a water pump module formed by connecting a plurality of water pump units in parallel through a power output module;
s2, carrying out load priority partitioning, wherein the partitioning comprises load priority data and corresponding load size data of the load priority partitioning according to the load size, and each load partition corresponds to each water pump unit one by one;
s3, adjusting the number of water pump units put into operation according to the output power of the power output module and the load priority data;
s4, according to the load priority data and the corresponding load size data, the subarea with high load priority is controlled to be firstly put into water pump operation, and the output power of each water pump unit which is put into operation corresponds to the load size.
Connect photovoltaic array and the water pump module that a plurality of water pump unit are parallelly connected to be constituteed through power output module still includes: an output power mathematical model is established based on the photovoltaic array to calculate the output power.
The embodiment timely converts the output power of the photovoltaic array into the input power of the water pump module in real time through the control module, the utilization and the optimized control of system energy are carried out by combining the load priority data of the load partition module, the number of the water pump units which are put into operation is determined, the actual input power of each water pump unit is determined according to the load size data, the flow of the water pump is controlled according to the actual demand of the load, the control mode is a real-time control mode for flexible input and cut-off of the water pump, and the control mode is different from a fixed mode of gradually starting or stopping, so that the technical problem that the matching degree of the photovoltaic array and the load is low is.
Embodiment 3 this embodiment provides another multi-parallel photovoltaic device control system optimization method
As shown in fig. 2, for the structure diagram of the multi-parallel photovoltaic device control system provided in this embodiment, the optimization method specifically includes the following steps:
(1) determining the number of subunits to be put into operation
In order to improve the matching degree between the photovoltaic power generation side and the load side, the central controller needs to adjust the number of water pump units which are put into operation according to the energy output by the photovoltaic power generation side, and the priority load is supplied and demanded. For a single water pump unit to be put into operation, its operating power P0Satisfies the following formula:
Pm≤P0≤PM (1)
wherein, PmThe minimum active power of the water pump when the water pumping threshold is reached; pMThe maximum active power of the water pump operation, namely the rated power of the water pump. When the photovoltaic array outputs power PPVThe input power converted to the water pump is P, and when P is a constant value, n is providedsWhen each water pump unit is put into operation, the following holds true:
P/PM≤ns≤P/Pm (2)
according to the formula, when the output power of the photovoltaic array is smaller and lower than the power required by the water pumping threshold of a single water pump, the water-free pump is put into operation. When the output power of the photovoltaic array is higher than the power required by the water pumping threshold of a single water pump but lower than the power required by the water pumping threshold of two water pumps, only one water pump is put into operation. When the output power of the photovoltaic array meets the minimum power required by the water pumping threshold values of the two water pumps, the two water pumps are put into use, and the output power of the photovoltaic array is uniformly distributed between the two water pumps. When the output power of the photovoltaic array meets the minimum power required by the water pumping threshold values of the three water pumps, the three water pumps are put into use, and the output power of the photovoltaic array is uniformly distributed among the three water pumps. Thus, the water pump unit is completely put into operation. Meanwhile, the water pump which is put into operation firstly corresponds to the load which needs to be supplied preferentially, so that the load in the area can be supplied preferentially.
(2) Determining power distribution principles among parallel sub-units
Assuming that n water pump units are connected in parallel, the theoretical total input power of the water pump units is P (), and the active power of each water pump unit is P1,P2,…,Pi,…,PnAnd the rated power P of the water pumpMAnd a maximum flow rate QMLet k be Q for a known valueM/PM 1/3From the water pump model formula (8) in embodiment 1, it can be obtained:
Figure BDA0002717330440000101
the first and second derivatives are calculated for the above equation:
Figure BDA0002717330440000111
Figure BDA0002717330440000112
due to k>0,Pi>0, then d2Qi/dPi 2<0, therefore, QiIs about PiThe convex function of (a) is obtained from the kinson inequality:
Figure BDA0002717330440000113
if and only if P1＝P2＝…＝PnAnd when the above equation is established, namely the output power of the photovoltaic array is equally divided by each parallel subunit, the output flow of the water pump of each subunit reaches the maximum value.
Therefore, when more than one water pump unit is put into operation and each parallel subunit equally divides the output power of the photovoltaic array, each subunit obtains the maximum flow.
(3) Determining the flow of a water pump in a stator unit
Synthesizing the two steps, adjusting the number of the water pump units which are put into operation along with the change of the output power of the photovoltaic array, and simultaneously, equally dividing the output power of the photovoltaic array by each parallel subunit which is put into operation, wherein the output flow of the water pump of the subunit is as follows:
Figure BDA0002717330440000114
when the illumination is weak and the input power of the water pump is lower than the water pumping threshold value of the single water pump unit, the flow of the single water pump is zero; when the input power divided by each parallel subunit is higher than a water pumping threshold value and lower than the rated power of the operation of the water pump, the output flow of the water pump changes along with the change of the input power divided by the subunits; and when the energy divided by each parallel subunit is higher than the rated power of the water pump, the water pump operates at the maximum flow.
Assume that the relevant parameters in the water pump control system are as shown in the following table:
Figure BDA0002717330440000121
TABLE 1
Taking four water pump units as an example, the input and operation states of the photovoltaic device control system units are verified, and the water pump flow is shown in fig. 3 along with the change of the water pump quantity and the input power. As can be seen from fig. 3, in the process of gradually increasing the output power of the photovoltaic array, each water pump unit is sequentially put into operation, so that the defect that the photovoltaic equipment control system in single-machine operation cannot be started under the condition of low input power due to an excessively high pumping threshold is overcome, and the waste of solar energy is avoided. Simultaneously, along with the change of solar energy, the load supply and demand are adjusted, the load energy which needs to be supplied preferentially is supplied preferentially, and the matching degree of the photovoltaic power generation side and the load side is improved.
When the solar input power can not meet the condition that the water pumps of all the parallel subunits are started to operate, the area and the load which need preferential water supply and irrigation are started first, so that crops with high priority, severe drought or high added value are preferentially supplied and irrigated, and the water supply utilization rate and the economic efficiency are improved.
When the solar input power can meet the requirement that a plurality of water pump units are put into operation and the water pump is fully ensured to operate at full power, each parallel subunit distributes the output power of the solar photovoltaic array according to the power uniform division principle, so that the flow of each subunit is ensured to be maximum, and the irrigation is more uniform.
When the solar input power can meet the requirement that a plurality of water pump units are put into operation but the full-power operation of the water pumps cannot be guaranteed, power distribution is carried out on each parallel subunit according to the lift requirement, the flow of each unit water pump is continuously adjusted according to the change of the output power of the photovoltaic array, the lift and the flow of each irrigation area are fully utilized, and the area of the irrigation area is as large as possible. Supposing that the conversion efficiency of the system is neglected, the specifications of the water pumps of the parallel sub-units are the same, the power required by the load is 500W, the system comprising one to six water pump units is respectively established, the minimum input power corresponding to the starting of the water pumps is 1100W,500W,400W,250W,250W and 100W, the smaller the starting rated power is, the smaller the load shortage is, the system flow is calculated when the equivalent output power of the photovoltaic array is continuously changed, the difference value between the power required by the actual load and the output power of each water pump unit is defined as the load shortage, and the ratio of the load shortage to the power required by the actual load is defined as the load shortage rate. The load shortage for systems with different numbers of water pump units is shown in fig. 4.
As can be seen from fig. 4, when the number of the water pump units connected in parallel is greater than 1, the load corresponding to each of the sub-units connected in parallel is reduced, and the capacity of the corresponding water pump connected in parallel is reduced, so that the "water pumping threshold" of the system is obviously reduced, and at this time, when the input power is low, the water pump units start to be put into operation in sequence. Under the condition that the output power of the photovoltaic arrays is the same, the more the number of the water pump units put into operation is, the smaller the shortage rate of the load is, namely, the photovoltaic equipment control system with a plurality of machines running in parallel can improve the utilization rate of solar energy and reduce the shortage rate of the load. On the other hand, the load shortage rate of the system with more water pump units is reduced at a higher speed along with the increase of the input power, namely, the input power required by meeting the load can be reduced by properly increasing the number of the water pump units connected in parallel.
When the load shortage is zero, i.e. the load demand is fully met, the relation between the number of water pump units connected in parallel and the input power is shown in fig. 5. As can be seen from fig. 5, compared to the conventional photovoltaic device control system operated in a single machine, the photovoltaic device control system operated in parallel with multiple machines has a significantly reduced output power of the photovoltaic array meeting the load requirement, that is, under the condition of the same load requirement, the photovoltaic device control system operated in parallel with multiple machines needs less input solar energy, and has a higher energy utilization rate.
In the process that the output power of the photovoltaic array is gradually increased, the water pump units are sequentially put into operation, the defect that a photovoltaic equipment control system in single-machine operation cannot be started under the condition of low input power due to the fact that a water pumping threshold value is too high is overcome, and waste of solar energy is avoided. Simultaneously, along with the change of solar energy, the load supply and demand are adjusted, the load energy which needs to be supplied preferentially is supplied preferentially, and the matching degree of the photovoltaic power generation side and the load side is improved.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that although the present specification describes the embodiments, the above-mentioned embodiments are exemplary and not intended to limit the scope of the present invention, and any changes, modifications, substitutions and alterations made by those skilled in the art without departing from the principle and spirit of the present invention shall be included in the scope of the present invention.

Claims (10)

1. A multi-machine parallel photovoltaic equipment control system is characterized by comprising:
a photovoltaic array for generating electricity;
the water pump module comprises a plurality of water pump units connected in parallel, wherein each water pump unit comprises a frequency conversion subunit, an electric subunit and a water outlet subunit;
the load partitioning module is provided with load priority data for partitioning the load priority according to the load size and corresponding load size data; each load partition corresponds to each water pump unit one by one;
the power output module is connected with the photovoltaic array to output stable direct current to the water pump module;
the control module is used for generating a control signal according to the output power and the load priority data of the power output module and the corresponding load size data and transmitting the control signal to the water pump module;
the control signal controls the subareas with high load priority levels to be put into the water pumps to operate firstly so as to determine the number of the parallel water pump units which are put into operation;
and the control signal adjusts the input power of each parallel water pump unit which is put into operation to correspond to the load priority level one by one.
2. The multi-parallel photovoltaic device control system of claim 1, wherein each load zone of the load zone modules comprises a plurality of sub-zones; each sub-partition is provided with a humidity sensor.
3. The multi-machine parallel photovoltaic device control system of claim 2, wherein the load priority zone information comprises humidity information, and the humidity sensor feeds back the humidity data to the control module to generate the corresponding control signal.
4. The multi-parallel photovoltaic device control system of claim 1, wherein the control module comprises:
the model establishing submodule is used for establishing a mathematical model of the output power of the photovoltaic array;
the obtaining submodule is used for obtaining the output power data of the power output module, the load priority data of the load partitioning module and the corresponding load size data based on the first model establishing submodule;
the processing submodule is used for processing the output power data acquired by the acquisition submodule;
the determining submodule is used for determining the number of the parallel water pump units which are put into operation according to the load priority data;
and the control submodule is used for controlling the subarea with high load priority level to be firstly put into water pump operation and controlling the input power of each parallel water pump unit to be put into operation to be in one-to-one correspondence with the load priority level according to the output power data processed by the processing submodule, the load priority level data and the corresponding load size data of the load subarea module and the number of the parallel water pump units put into operation.
5. The multi-parallel photovoltaic equipment control system of claim 3, wherein the control module is electrically connected with the water pump module; and each water pump unit is electrically connected with the photovoltaic array and the power output module respectively.
6. The system as claimed in claim 5, wherein the control module is electrically connected to the frequency conversion subunit of the water pump module to adjust the input power of each parallel water pump unit in operation to correspond to the priority level of the load.
7. The multi-machine parallel photovoltaic equipment control system of claim 1, wherein the electric subunit of each water pump unit is connected with the frequency conversion subunit and the water outlet subunit of the water pump unit; the frequency conversion subunit is connected with the photovoltaic array and the power output module.
8. The system of claim 1, wherein the inverter sub-unit comprises an inverter; the electrical subunit comprises an electrical motor; the water outlet subunit comprises a water pump.
9. An optimization method based on the photovoltaic equipment control system of any one of claims 1 to 8, characterized in that: the optimization method comprises the following steps:
connecting the photovoltaic array with a water pump module formed by connecting a plurality of water pump units in parallel through a power output module;
carrying out load priority zoning, wherein the zoning comprises load priority data and corresponding load size data for carrying out the load priority zoning according to the load size, and each load zoning corresponds to each water pump unit one by one;
adjusting the number of water pump units put into operation according to the output power of the power output module and the load priority data;
and controlling the subarea with high load priority to be put into the water pump to operate firstly according to the load priority data and the corresponding load size data, wherein the output power of each water pump unit put into operation corresponds to the load size.
10. The optimization method of claim 9, wherein: the water pump module that constitutes with photovoltaic array and a plurality of water pump unit are parallelly connected through power output module is connected still includes: an output power mathematical model is established based on the photovoltaic array to calculate the output power.
CN202011077829.3A 2020-10-10 2020-10-10 Multi-machine parallel photovoltaic equipment control system and optimization method Pending CN112360731A (en)

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