CN113623166A - Control method of multi-pump parallel photovoltaic pumping system, inverter and photovoltaic pumping system - Google Patents

Control method of multi-pump parallel photovoltaic pumping system, inverter and photovoltaic pumping system Download PDF

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CN113623166A
CN113623166A CN202110829614.0A CN202110829614A CN113623166A CN 113623166 A CN113623166 A CN 113623166A CN 202110829614 A CN202110829614 A CN 202110829614A CN 113623166 A CN113623166 A CN 113623166A
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slave
water pump
frequency
photovoltaic
inverter
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CN113623166B (en
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陈锐坚
王晓冉
徐政
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SHENZHEN SOLARTECH RENEWABLE ENERGY CO Ltd
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SHENZHEN SOLARTECH RENEWABLE ENERGY CO Ltd
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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
    • 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
    • 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
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/66—Regulating electric power
    • G05F1/67—Regulating electric power to the maximum power available from a generator, e.g. from solar cell
    • 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
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Control Of Non-Positive-Displacement Pumps (AREA)
  • Inverter Devices (AREA)

Abstract

A control method of a multi-pump parallel photovoltaic pumping system, an inverter and the photovoltaic pumping system. The invention discloses a control method of a multi-pump parallel photovoltaic pumping system, which comprises the following steps: when the host inverter is powered on and operates, the operating frequency of the host water pump is adjusted through a maximum power tracking mode; when the operating frequency of the master water pump is greater than or equal to a first preset frequency, an operating instruction carrying a target value of the operating frequency of the slave is sent to one of the slave inverters, and the control mode is switched to a normal pressure method control mode; when the operating frequency of the master water pump is less than or equal to a second preset frequency, sending a stop instruction to one slave inverter, sending an instruction carrying a slave operating frequency target value to the remaining slave inverters, and switching to a normal-pressure control mode; and when the water pump of the slave reaches the target value of the running frequency of the slave, the inverter of the master is switched to the maximum power tracking mode, and the running frequency of the water pump of the slave is synchronously adjusted. Compared with the prior art, the invention greatly reduces the requirement on the real-time communication rate of the master-slave communication system, and can meet the requirement by adopting a simple, cheap and easily-realized communication mode.

Description

Control method of multi-pump parallel photovoltaic pumping system, inverter and photovoltaic pumping system
Technical Field
The invention relates to the technical field of photovoltaic pumping, in particular to a control method of a multi-pump parallel photovoltaic pumping system, an inverter and the photovoltaic pumping system.
Background
In recent years, photovoltaic pumping systems have been widely researched and applied. Generally, a photovoltaic pumping system comprises a photovoltaic array, a special inverter and a single water pump, wherein the special inverter can implement speed regulation control on the single water pump according to the change of incident solar irradiance of the photovoltaic array, so as to realize Maximum Power Point Tracking (MPPT). The system design takes into account the performance indexes such as the daily average effective operation time, the photovoltaic array power generation efficiency, the water pumping efficiency and the like under different seasons and weather conditions, and appropriate redundancy coefficients are reserved for the configuration of the water pumping lift and the peak power of the photovoltaic array so as to ensure good comprehensive operation efficiency. However, under the influence of the characteristics of the centrifugal pump, the operation efficiency of the system under the conditions of strong light and weak light still does not reach an ideal state, under the condition of strong light, the water pump reaches rated power, the photovoltaic energy of the redundancy design part of the system cannot be utilized, and under the condition of weak light, the centrifugal water pump operates at a lower rotating speed, the efficiency is low, and even the water outlet lift and the idle energy cannot be reached.
Based on this, people provide a photovoltaic pumping system with multiple pumps connected in parallel, namely the photovoltaic pumping system comprises a set of photovoltaic array and multiple sets of photovoltaic pumps arranged in parallel, and the number of the operating water pumps is switched according to the change of solar irradiance in the operating process. On the one hand, the water pump runs at a high rotating speed during weak illumination, the minimum power limitation of water lifting of the high-lift water pump is reduced, and the photovoltaic power generation utilization efficiency is improved.
When the photovoltaic water pumps are realized, the multiple sets of photovoltaic water pumps comprise a host and multiple slaves, the photovoltaic water pump host acquires the output power of the photovoltaic array, gives a starting or stopping instruction to the slaves according to the illumination enhancement or weakening condition, and rapidly updates the operating frequency instruction in real time, achieves the frequency synchronization regulation effect, and realizes the photovoltaic maximum power tracking. However, the system requires fast, stable and reliable communication speed, and due to the delay caused by communication, the maximum power tracking effect is easily affected, which results in reduced system efficiency, oscillation of operating frequency and even system breakdown.
Disclosure of Invention
In view of the above, there is a need to provide a control method for a multi-pump parallel photovoltaic pumping system, so as to solve the technical problems that when the conventional photovoltaic pumping system host controls the slave to be started or stopped and adjusts the operating frequency of the slave, the requirement on a master-slave communication system is high, and when the communication system fluctuates, the maximum power tracking effect is easily affected, so that the system efficiency is reduced, the operating frequency is oscillated, and even the system is broken down.
In order to achieve the above object, an embodiment of the present invention provides a control method for a multi-pump parallel photovoltaic pumping system, including the following steps:
when the host inverter is powered on and operates, the operating frequency of the host water pump is adjusted through a maximum power tracking mode;
when the operating frequency of the master water pump is greater than or equal to a first preset frequency, an operating instruction carrying a slave operating frequency target value is sent to one of the slave inverters to control the corresponding slave water pump to start, and the master inverter is switched to a normal pressure method control mode;
when the operating frequency of the master water pump and the slave water pumps is less than or equal to a second preset frequency, sending a stop instruction to one of the slave inverters in operation, and sending an instruction carrying a slave operating frequency target value to the remaining slave inverters in operation to control and adjust the operating frequency of the corresponding slave water pump, wherein the master inverter is switched to a normal pressure method control mode;
and when the running frequency of the water pump of the slave machine reaches the target value of the running frequency of the slave machine, the host machine inverter is switched from the normal-pressure control mode to the maximum power tracking mode, and the running frequency of the water pump of the slave machine is synchronously adjusted.
Optionally, when the operating frequency of the master water pump is greater than or equal to a first preset frequency, the master inverter executes the step of sending an operating instruction carrying a target value of the operating frequency of the slave to one of the slave inverters;
and when the operating frequency of the master water pump and the slave water pump is less than or equal to a second preset frequency, the master inverter executes the step of sending a stop instruction to one of the slave inverters in operation and sending an instruction carrying a slave operating frequency target value to the rest slave inverters in operation.
Optionally, the multi-pump parallel photovoltaic pumping system further comprises a monitor, and the monitor is connected with the master inverter and the slave inverter;
when the running frequency of the main machine water pump is greater than or equal to a first preset frequency, the monitor executes the step of sending a running instruction carrying a target value of the running frequency of the slave machine to one of the slave machine inverters, and the monitor controls the main machine inverter to be switched to a normal pressure method control mode;
when the operating frequency of the master water pump and the operating frequency of the slave water pumps are less than or equal to a second preset frequency, the monitor executes the step of sending a stop instruction to one of the slave inverters in operation and sending an instruction carrying a slave operating frequency target value to the remaining slave inverters in operation, and the monitor controls the master inverter to be switched to a normal-pressure control mode.
Optionally, the monitor is further configured to determine one of the at least two sets of photovoltaic water pumps connected in parallel as a photovoltaic water pump host according to the running time of each set of photovoltaic water pump, so as to achieve running time balance of each set of photovoltaic water pump.
Optionally, the step of synchronously adjusting the operating frequency of the slave water pump specifically includes:
and adjusting the running frequency of the water pump of the slave machine by adopting a frequency delay synchronization mechanism.
Optionally, adjusting the operating frequency of the slave water pump by using a frequency delay synchronization mechanism includes the following steps:
acquiring the current running frequency of a host water pump and the running frequency of a slave water pump;
when the operating frequency of the master water pump is smaller than the rated frequency and the difference between the operating frequency of the master water pump and the operating frequency of the slave water pump is larger than a set hysteresis frequency value, calculating an updated value of the operating frequency of the slave water pump and adjusting the operating frequency of the slave water pump to the updated value of the operating frequency of the slave, wherein the calculation method of the updated value of the operating frequency of the slave is as follows:
Fs’＝sqrt3((N*Fst 3+Fmt 3)/(N+1)) if(|Fmt-Fst|≥Fband) (N≥1)
when the running frequency of the master water pump reaches the rated frequency, accumulating preset component values delta F at fixed time to calculate an updated value of the running frequency of the slave water pump, and adjusting the running frequency of the slave water pump to the updated value of the running frequency of the slave, wherein the method for calculating the updated value of the running frequency of the slave is as follows:
Fs’＝Fst+ΔF if(Fmt＝F0，(Fmt-Fst)<Fband)
wherein, F0Is the rated frequency of the main engine water pump, Fs' updating the value for the slave operating frequency, FmtFor the current operating frequency of the main engine water pump, FstThe current operation frequency of the slave water pumps, N the number of the current operation slave water pumps, FbandAnd setting a hysteresis frequency value for the reference value.
Optionally, when starting a water pump of a slave machine, the method for calculating the target value of the running frequency of the slave machine includes:
Fs＝sqrt3((N+1)/(N+2))F0
when one slave water pump is shut down, the calculation method of the slave operation frequency target value comprises the following steps:
Fs＝sqrt3((N*Fst 3+Fmt 3)/N)
where N is the number of currently operating slave water pumps, F0Rated frequency of the main engine water pump, FmtFor the current operating frequency of the main engine water pump, FstPumping current slave waterLine frequency, FsIs the target value of the running frequency of the slave machine.
8. An inverter, comprising a memory and a processor, wherein the memory has stored thereon a computer program, which, when executed by the processor, causes the processor to carry out a method of controlling a multi-pump parallel photovoltaic lift system according to any of claims 1 to 7.
9. The multi-pump parallel photovoltaic pumping system is characterized by comprising a photovoltaic array and at least two sets of photovoltaic water pumps connected in parallel, wherein one photovoltaic water pump is a photovoltaic water pump host, the rest photovoltaic water pumps are photovoltaic water pump slave machines, the photovoltaic water pump host comprises a host inverter and a host water pump, the photovoltaic water pump slave machines comprise slave inverter and slave water pumps, and the host inverter is the inverter according to claim 8.
Another embodiment of the present invention provides an inverter, including a memory and a processor, where the memory stores a computer program, and when the computer program is executed by the processor, the processor is enabled to implement the control method of the multi-pump parallel photovoltaic pumping system as described above.
The invention further provides a multi-pump parallel photovoltaic pumping system, which comprises a photovoltaic array and at least two sets of photovoltaic water pumps connected in parallel, wherein one photovoltaic water pump is a photovoltaic water pump host, the rest photovoltaic water pumps are photovoltaic water pump slave machines, the photovoltaic water pump host comprises a host inverter and a host water pump, the photovoltaic water pump slave machines comprise slave inverter and slave water pumps, and the host inverter is the inverter.
The invention further provides a multi-pump parallel photovoltaic pumping system, which comprises a photovoltaic array, at least two sets of photovoltaic water pumps connected in parallel and a monitor, wherein one photovoltaic water pump is a photovoltaic water pump host, the rest photovoltaic water pumps are photovoltaic water pump slaves, the photovoltaic water pump host comprises a host inverter and a host water pump, the photovoltaic water pump slaves comprise a slave inverter and a slave water pump, the monitor is connected with the host inverter and the slave inverter, and the monitor is the monitor.
Compared with the prior art, the control method of the multi-pump parallel photovoltaic pumping system provided by the embodiment of the invention has the advantages that in the process of starting or stopping the slave machine according to the illumination condition, when the running frequency of the slave machine is regulated, the master machine inverter works in a normal pressure method control mode, when the slave machine works at a constant frequency, the master machine inverter adopts a maximum power tracking mode, at the moment, the slave machine water pump can be regarded as a constant load, the input power change condition detected by the master machine inverter can reflect the photovoltaic array input power change condition of the whole photovoltaic pumping system, and all slave machine state parameters do not need to be obtained through real-time communication and then calculated, the real-time performance and the accuracy of the maximum power tracking of the photovoltaic pumping system are improved, the requirement on the real-time communication rate of the master machine communication system and the slave machine communication system is greatly reduced, and the application requirement can be met by adopting a simple, low and easy-to-realize communication mode, the influence on the maximum power tracking effect and the system efficiency when the communication speed fluctuates is relieved to a great extent.
Drawings
Fig. 1 is a schematic structural diagram of a multi-pump parallel photovoltaic pumping system in the prior art.
Fig. 2 is a flowchart of a control method of a multi-pump parallel photovoltaic pumping system according to an embodiment of the present invention.
Fig. 3 is a flowchart of a control method of a multi-pump parallel photovoltaic pumping system according to another embodiment of the present invention.
Fig. 4 illustrates the operation principle of the control mode of the normal pressure method in the embodiment of the present invention.
Fig. 5a is a photovoltaic simulated power curve of a photovoltaic pumping system under cloudy weather conditions.
Fig. 5b is a measured curve of the output power.
Fig. 5c is a measured curve of water pump flow.
Fig. 6 is a comparative test chart of water lifting effect when the three-pump system and the single-pump system are operated.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1, fig. 1 is a system block diagram of a conventional multi-pump parallel photovoltaic pumping system, and it can be seen that the multi-pump parallel photovoltaic pumping system includes a set of photovoltaic arrays 10 and a plurality of sets of photovoltaic pumps 20 arranged in parallel. Each group of photovoltaic water pumps 20 includes an inverter 201 and a corresponding water pump 202. When the photovoltaic pumping system works, one of the photovoltaic water pumps 20 serves as a photovoltaic water pump host, the other groups serve as photovoltaic water pump slaves, the photovoltaic water pump host and the photovoltaic water pump slaves can communicate with each other, and instructions such as starting, stopping and operating frequency of the slaves are given by the host. For convenience of description later, an inverter in a master of the photovoltaic water pump is referred to as a master inverter, a water pump is referred to as a master water pump, and an inverter in a slave of the photovoltaic water pump is referred to as a slave inverter and a water pump is referred to as a slave water pump. Wherein the number of photovoltaic water pumps 20 may be 2, 3, 4 or more.
Based on the multi-pump parallel photovoltaic pumping system shown in fig. 1, an embodiment of the invention provides a control method of a multi-pump parallel photovoltaic pumping system, which is used for solving the technical problems that when a host controls a slave to start or stop and adjusts the operation frequency of the slave in the existing multi-pump parallel photovoltaic pumping system, the requirement on a master-slave communication system is high, and when the communication system fluctuates, the maximum power tracking effect is easily influenced, so that the system efficiency is reduced, the operation frequency is oscillated, and even the system is crashed.
Example 1
Referring to fig. 2, the present embodiment provides a method for controlling a multi-pump parallel photovoltaic pumping system, including the following steps:
and S101, when the host inverter is powered on and operates, the operating frequency of the host water pump is adjusted through a maximum power tracking mode.
After the host inverter is powered on and operated, the host inverter firstly enters a maximum power tracking mode, the input power input to the host inverter by the photovoltaic array is detected in the maximum power tracking mode, the operating frequency of the host water pump is adjusted according to the change condition of the input power, and maximum power tracking is achieved. The maximum power tracking technology is mature, and the present embodiment does not limit the technology.
Step S102, when the operating frequency of the master water pump is increased to be greater than or equal to a first preset frequency, an operating instruction carrying a target value of the operating frequency of the slave is sent to one of the slave inverters to control the corresponding slave water pump to start, and the master inverter is switched to a normal pressure control mode.
In the working process of the photovoltaic water pumping system, if the illumination is gradually enhanced, when the illumination is enhanced to a certain degree, one slave water pump can be added, an operation instruction is sent to one slave inverter which is not in a working state, the operation instruction carries a slave operation frequency target value, the slave water pump is started after the slave inverter receives the operation instruction, and the operation frequency of the slave water pump is adjusted according to the received slave operation frequency target value.
Specifically, in this embodiment, the condition that the illumination is enhanced to a certain extent and the operation of one slave water pump is increased is as follows: the running frequency of the main water pump is increased to a first preset frequency, and preferably, the first preset frequency is the rated frequency F of the main water pump0So arranged that the water pump is at a rated frequency F0When the water pump runs at low temperature, the water lifting efficiency is relatively high, and the running water pump reaches the rated frequency F0The optimal system water lifting efficiency can be obtained when the starting condition of the next slave machine is set. Of course, in other embodiments, the starting condition for increasing the operation of the slave machines, that is, the first preset frequency, may also be set as a non-rated frequency point, and at this time, after all the slave machines are started in sequence according to the flow, the master inverter continues to execute the maximum power tracking algorithm, so as to gradually increase the frequency of all the slave machines to the rated frequency.
Wherein the slave operation frequency target value FsThe calculation principle of (2) is as follows: the input power of the current photovoltaic array can support all running water pumps after pump increasing action to run at the same speed according to the calculated frequency, namely after a slave is added to run, all the running water pumps (including a master water pump and all slave water pumps in a running state) in the photovoltaic pumping system run with the slaveTarget value F of operating frequencysThe total power in the same-speed operation is not more than the current input power of the photovoltaic array. Specifically, according to the theoretical relation of the cubic linear correlation of the centrifugal water pump power and the frequency, the target value F of the running frequency of the slave is obtained through derivationsThe calculation formula of (a) is shown in formula 1:
Fs＝sqrt3((N+1)/(N+2))F0formula 1
Wherein N is the number of the slave water pumps currently running in the photovoltaic pumping system, and F0The rated frequency of the main machine water pump.
Step S103, when the operating frequencies of the master water pump and the slave water pumps are less than or equal to a second preset frequency, a stop instruction is sent to one of the slave inverters in operation, an instruction carrying a slave operating frequency target value is sent to the remaining slave inverters in operation to adjust the operating frequency of the corresponding slave water pump, and the master inverter is switched to a normal pressure method control mode.
In the working process of the photovoltaic water pumping system, if the illumination is gradually weakened, when the illumination is weakened to a certain degree and one slave water pump needs to be shut down, a stop instruction is sent to one slave inverter in operation, instructions carrying slave operation frequency target values are sent to the remaining slave inverters in operation, the slave inverter receiving the stop instruction controls the corresponding slave water pump to stop working, and the other slave inverters in operation readjust the operation frequency of the slave water pump according to the received slave operation frequency target values.
Specifically, in this embodiment, the condition that the illumination is weakened to a certain extent and the water pump of one slave machine is turned off is as follows: the operating frequency of a water pump (comprising a host water pump and a slave water pump) operating in the photovoltaic pumping system is reduced to be less than or equal to a second preset frequency, wherein the second preset frequency is the lowest effective water outlet frequency F set by a userminWherein the lowest effective water outlet frequency F is obtained during field installation and debuggingminThe method is one of main factors influencing the system efficiency, can be obtained through simple trial operation, does not need high and deep professional knowledge, and is simple in system debugging and easy to implement.
Wherein the slave operation frequency target value FsThe calculation principle of (2) is as follows: the input power of the photovoltaic array can support that all running water pumps after pump reduction operation run at the same speed according to the calculated frequency, namely after one running slave is closed, the total power of all running water pumps (including a master water pump and all slave water pumps in a running state) in the photovoltaic pumping system when the running water pumps run at the same speed according to the running frequency target value of the slave is not more than the current input power of the photovoltaic array. Specifically, according to the theoretical relation of the cubic linear correlation of the centrifugal water pump power and the frequency, the target value F of the running frequency of the slave is obtained through derivationsThe calculation formula of (a) is shown in formula 2:
Fs＝sqrt3((N*Fst 3+Fmt 3) /N), wherein N is not less than 1 or 2
Wherein N is the number of slave water pumps currently running in the photovoltaic pumping system, FmtFor the current operating frequency of the main engine water pump, FstThe current running frequency of the water pump of the slave machine.
In step S102 and step S103, when the slave water pump operation frequency is in the regulation state, the master inverter operates in the normal pressure control mode. Specifically, referring to fig. 4, when the host inverter operates in the normal-pressure control mode, the following steps are performed: (1) detecting actual input voltage V of photovoltaic array by host inverterpv(ii) a (2) Calculating the actual input voltage VpvAnd a target voltage VmppAnd adjusting the operating frequency of the host water pump through the PI regulator to enable the actual input voltage V of the photovoltaic arraypvTo the target voltage VmppWherein the target voltage VmppRecording the input voltage of the photovoltaic array when the operating frequency of the water pump of the host is a first preset frequency or a second preset frequency, thereby regulating the load power P of the systemloadAdjusting the operating point of the photovoltaic array (operating voltage point V)pvPower point Ppv) And constant control over the input voltage of the photovoltaic array is realized.
Taking step S102 as an example, when a new slave water pump needs to be started along with the increase of illumination, the target voltage of the master inverter operating in the normal-pressure control mode is the input voltage of the photovoltaic array when the operating frequency of the master water pump reaches the first preset frequency. Similarly, in step S103, when one slave water pump needs to be stopped along with the decrease of the light, the target voltage of the master inverter operating in the normal-pressure control mode is the input voltage of the photovoltaic array when the operating frequency of the master water pump reaches the second preset frequency. By switching the host inverter to a normal pressure control mode and setting a target voltage, the working point of the photovoltaic array can be kept unchanged in the starting or stopping process of the slave, and if the illumination condition is not changed in the process, the operating frequency of the host water pump can theoretically reach the same operating frequency under the normal pressure control and regulation when the slave water pump reaches the operating frequency of the slave.
And step S104, when the slave water pump reaches the target value of the running frequency of the slave, the master inverter is switched from the normal pressure control mode to the maximum power tracking mode, and the running frequency of the slave water pump is synchronously adjusted according to the illumination condition.
Specifically, after the slave water pump reaches the slave operation frequency target value sent by the master inverter, the slave water pump continuously operates at the frequency, the slave water pump can be regarded as a constant load, the photovoltaic array input power change condition detected by the master inverter can reflect the photovoltaic input power change condition of the whole photovoltaic pumping system, the master inverter exits the normal pressure method control mode at the moment, the master inverter is switched to the maximum power tracking mode again, and the operation frequency of the slave water pump is synchronously adjusted according to the illumination condition.
In some embodiments, the master inverter uses a frequency delay synchronization mechanism to drive the slave inverter to adjust the operating frequency of the slave water pump. The principle is as follows:
when the host inverter runs at frequency FmtWith slave operating frequency FstThe difference is greater than a set hysteresis frequency value FbandIn time, the current slave operation frequency needs to be adjusted to the slave operation frequency updating value Fs', wherein the slave operating frequency updates a value FsThe calculation formula of' is shown in formula 3, and if the operation frequency F of the host inverter is in the processmtReaches its rated frequency F0Then, as shown in equation 4, a component value Δ F is added periodically to adjust the operating frequency of the slave until the operating frequency of the slave also reaches the rated frequency F0. Hysteresis frequency value F during field installation and debuggingbandThe method is another main factor influencing the efficiency of the system, can be obtained through simple commissioning and then is preset in the system, and the system is simple to debug and easy to implement.
Fs’＝sqrt3((N*Fst 3+Fmt 3)/(N+1)) if(|Fmt-Fst|≥Fband) (N.gtoreq.1) formula 3
Fs’＝Fst+ΔF if(Fmt＝F0，(Fmt-Fst)<Fband) Formula 4
And N is the number of the slave water pumps running in the photovoltaic pumping system.
By setting a frequency delay synchronization mechanism for the master machine and the slave machine of the photovoltaic water pump, the slave machine is kept to operate at a fixed frequency in a local time period, the master machine is used for photovoltaic maximum power tracking control, and the frequency of the slave machine is adjusted only when the frequency difference between the master machine and the slave machine reaches a certain threshold value, so that the speed and reliability requirements of the system on real-time communication are reduced, the operation frequency of the slave machine is relatively stable, the service life of the water pump of the slave machine is prolonged, and the stability and reliability of the system are enhanced. In addition, the running frequency difference of the master machine and the slave machine is not large, and the master machine and the slave machine are basically synchronous although time delay exists, so that the effect of running all the water pumps of the multi-pump system at the same speed can be achieved, and the efficiency of the system is improved. Similarly, when the slave machine adjusts the operation frequency, the master machine also enters the normal pressure method control mode until the operation frequency of the slave machine reaches the slave machine operation frequency updating value FsAnd the host exits the normal pressure control mode and enters the maximum power tracking mode.
If the running frequency of the master machine and the slave machine rises to the rated frequency F in the process of enhancing the illumination0At this time, the condition of increasing the operation of 1 slave machine water pump is met, and the step S102 and the step S104 are repeated, so that all the slave machines can be gradually started and operated to the rated frequency F0. In the process of continuously weakening illumination, if the running frequency of the master machine and the slave machine is reducedAnd when the frequency is less than or equal to the second preset frequency, the condition of reducing the operation of 1 slave water pump is met, the step S103 and the step S104 are repeated until all the slave water pumps are closed, and the host machine is shut down for protection and is restarted in a delayed manner after the operation frequency is reduced to the second preset frequency under the control of the maximum power tracking algorithm, so that the invalid work is avoided, and the service life of the water pump is prolonged.
Compared with the prior art, the control method of the multi-pump parallel photovoltaic pumping system has the advantages that in the process of starting or stopping the slave machine according to the illumination condition, when the running frequency of the slave machine is adjusted, the master machine works in a normal pressure method control mode, when the slave machine works at a constant frequency, the master machine adopts a maximum power tracking mode, at the moment, the water pump of the slave machine can be regarded as a constant load, the input power change condition detected by the inverter of the master machine can reflect the photovoltaic array input power change condition of the whole photovoltaic pumping system, the state parameters of all the slave machines do not need to be obtained through real-time communication and then calculated, the real-time performance and the accuracy of the maximum power tracking of the photovoltaic pumping system are improved, the requirement on the real-time communication rate of the master machine and the slave machine is greatly reduced, the application requirement can be met by adopting a simple, low-cost and easy-to realize communication mode, the maximum power tracking effect when the communication rate fluctuates is relieved to a great extent, The impact of system efficiency.
It should be noted that, in the embodiment shown in fig. 2, the starting and the shutdown of the slave of the photovoltaic water pump, the calculation of the target value of the operation frequency of the slave, and the calculation of the updated value of the operation frequency of the slave may be performed by the master inverter, or may be performed by an additional monitor.
When the host inverter executes the process, the host and the slave are communicated with each other, and when the operating frequency of the host water pump is greater than or equal to a first preset frequency, the host inverter calculates the target value of the operating frequency of the slave and sends an operating instruction carrying the target value of the operating frequency of the slave to one of the slave inverters; similarly, when the operating frequencies of the master water pump and the slave water pump are less than or equal to a second preset frequency, the master inverter calculates the target value of the slave operating frequency, sends a stop instruction to one slave inverter in operation, and sends stop instructions to the rest slave inverters in operationAnd carrying instructions of the target value of the running frequency of the slave machine. In addition, when a frequency delay synchronization mechanism is adopted for synchronization, the master inverter calculates the running frequency update value F of the slaves' and sent to the slave inverter.
When the process is executed by an additional monitor, the monitor is connected with the master inverter and the slave inverter, the master inverter and the slave inverter upload the own operating frequency information to the monitor, and the monitor controls the working mode switching of the master inverter, controls the slave to be started or closed and adjusts the operating frequency. Specifically, when the operating frequency of the master water pump is greater than or equal to a first preset frequency, the monitor calculates a slave operating frequency target value and sends an operating instruction carrying the slave operating frequency target value to one of the slave inverters, and the monitor controls the master inverter to switch to a normal pressure control mode; similarly, when the operating frequencies of the master water pump and the slave water pumps are less than or equal to a second preset frequency, the monitor calculates a slave operating frequency target value, sends a stop instruction to one slave inverter in operation, sends an instruction carrying the slave operating frequency target value to the remaining slave inverters in operation, and controls the master inverter to switch to a normal pressure control mode.
Example 2
Referring to fig. 3, the present embodiment provides a control method for a multi-pump parallel photovoltaic pumping system, where the control method describes a whole process from a master to a plurality of slaves being gradually started to a plurality of slaves being gradually closed and the master being closed along with a change condition that light is continuously increased and reduced after the photovoltaic pumping system is started, and the master controls the slaves to be started, to be closed and to adjust an operation frequency, and includes the following steps:
step S201, the host inverter is powered on to operate, and the operating frequency of the host water pump is adjusted through a maximum power tracking mode.
Step S202, determining whether the operating frequency of the host water pump is greater than or equal to the rated frequency, if so, executing step S203, and if not, executing step S208.
In this embodiment, with the increase of the illumination, the conditions for newly starting a slave water pump are as follows: the running frequency of the main machine water pump reaches the rated frequency F0I.e. the first predetermined frequency is the rated frequency F0。
Step S203, the master inverter records the current input voltage of the photovoltaic array, calculates the target value of the slave operation frequency, sends an operation instruction carrying the target value of the slave operation frequency to one of the slave inverters, and switches to a normal pressure control mode.
Wherein the slave operation frequency target value FsIs as shown in formula 1 in example 1:
Fs＝sqrt3((N+1)/(N+2))F0formula 1
And N is the number of slave water pumps currently running in the photovoltaic pumping system.
Gradually increasing the frequency of the water pump of the slave to a target value F of the running frequency of the slave after the water pump of the slave is startedsIn the process of the method, because the frequency of the water pump of the slave machine is changed, the inverter of the host machine cannot reflect the change condition of the photovoltaic input power of the whole photovoltaic pumping system according to the change condition of the photovoltaic input power detected by the inverter of the master machine, and therefore a maximum power tracking algorithm cannot be carried out. At the moment, the host inverter is switched from the maximum power tracking mode to the normal-pressure control mode. And the host inverter records the current input voltage V of the photovoltaic arraymppAnd the target voltage is used as the target voltage in the normal pressure control mode, so as to ensure that the working point of the photovoltaic array of the master inverter in the starting process of the slave is kept unchanged, if the illumination condition is not changed in the process, the master operating frequency also reaches the same operating frequency theoretically after the slave water pump reaches the slave operating frequency under the control and regulation of the normal pressure method.
And step S204, starting the slave inverter and adjusting the operation frequency to the target value of the slave operation frequency.
Step S205, when the slave water pump is adjusted to the target value of the slave operation frequency and the frequency is maintained unchanged, the master inverter is switched to the maximum power tracking mode, and the slave inverter is driven to adjust the operation frequency of the slave water pump through the frequency delay synchronization mechanism.
Namely when the water pump of the slave reaches the target value F of the running frequency of the slavesAt the frequency FsWhen the system continuously operates, the water pump of the slave machine can be regarded as a constant load, and the change situation of the photovoltaic input power detected by the inverter of the host machine can reflect the change situation of the photovoltaic input power of the system, so that the inverter of the host machine exits the normal pressure method control mode, enters the maximum power tracking mode, and drives the slave machine to adjust the operating frequency along with the change of sunshine through the frequency delay synchronization mechanism. Therefore, the operation of one additional slave water pump is realized, the operation frequency of the master machine and the slave machine is kept synchronous, and then whether the operation frequency of the master water pump and the operation frequency of the slave machine water pump in operation are larger than or equal to the rated frequency is continuously detected along with the increase of the illumination intensity, so that the starting of other slave machine water pumps is controlled until all the slave machine water pumps are started. It should be noted that, in the process of adjusting the operating frequency of the slave machine through the frequency delay synchronization mechanism, if the operating frequency of the slave machine is changed, the master inverter operates in the normal-pressure control mode, and if the operating frequency of the slave machine is fixed, the master inverter operates in the maximum power tracking mode.
Step S206, detecting and judging whether the running frequency of the master water pump and the slave water pump is greater than or equal to the rated frequency, if so, executing step S207, and if not, executing step S210.
Step S207, determining whether all the slaves are already running, if yes, executing step S205, otherwise, returning to step S203.
Step S208, determining whether the operating frequency of the host water pump is less than or equal to the lowest effective water outlet frequency, if so, executing step S209, and if not, continuing to execute step S201.
In this embodiment, as the light is weakened, the condition for turning off the water pump of one slave machine is as follows: the running frequency of the main machine water pump is reduced to the lowest effective water outlet frequency FminThat is, the second predetermined frequency is the lowest effective water outlet frequency Fmin. When the running frequency of the main engine is reduced to the lowest effective water outlet frequency FminAfter that, the machine is stopped for protection and the time delay is heavyAnd starting, avoiding invalid work and prolonging the service life of the water pump.
And step S209, closing the main water pump and restarting in a delayed mode.
Step S210, determining whether the operating frequency of the master water pump and the slave water pump is less than or equal to the lowest effective water outlet frequency, if so, executing step S211, and if not, continuing to execute step S205.
Step S211, a stop instruction is sent to one of the slave inverters in operation, an instruction carrying a slave operation frequency target value is sent to the remaining slave inverters in operation, the master inverter is switched to a normal pressure method control mode, and the slave inverters adjust the slave water pump to reach the slave operation frequency target value.
Target value F of operation frequency of slave machine in step S211sThe calculation principle of (2) is as follows: the input power of the current photovoltaic array can support all running water pumps after pump reduction to run at the same speed according to the calculated frequency, namely after one running slave is closed, all running water pumps (including a master water pump and all slave water pumps in a running state) in the photovoltaic pumping system run at the target value F of the running frequency of the slavesThe total power in the same-speed operation is not more than the current input power of the photovoltaic array. In particular, the slave operating frequency target value FsThe formula for calculation of' is shown in formula 2 in example 1:
Fs＝sqrt3((N*Fst 3+Fmt 3) /N), wherein N is not less than 1 or 2
Wherein N is the number of slave water pumps currently running in the photovoltaic pumping system, FmtFor the current operating frequency of the main engine water pump, FstThe current running frequency of the water pump of the slave machine.
Step S212, determining whether all the slaves are turned off, if yes, executing step S201, otherwise executing step S205.
Compared with the prior art, in the control method of the multi-pump parallel photovoltaic pumping system, the master inverter starts or stops the slave according to the illumination condition, the slave operates in a normal pressure control mode when the operation frequency of the slave is adjusted, the maximum power tracking mode is adopted when the slave operates at a constant frequency, the slave water pump can be regarded as a constant load, the input power change condition detected by the master inverter can reflect the photovoltaic array input power change condition of the whole photovoltaic pumping system, the slave state parameters are not required to be obtained through real-time communication and then calculated, the real-time performance and the accuracy of the maximum power tracking of the photovoltaic pumping system are improved, the requirement on the real-time communication rate of a master-slave communication system is greatly reduced, the application requirement can be met by adopting a simple, low-cost and easy-to-realize communication mode, the maximum power tracking effect when the communication rate fluctuates is relieved to a great extent, The impact of system efficiency; meanwhile, the master machine and the slave machine of the photovoltaic water pump adopt a frequency delay synchronization mechanism, the slave machine keeps constant-frequency operation in a local time period, the master machine performs photovoltaic maximum power tracking control, and the frequency of the slave machine is adjusted after the frequency difference of the master machine and the slave machine reaches a certain threshold value, so that the speed and reliability requirements of the system on real-time communication are reduced, the operation frequency of the slave machine is relatively stable, the service life of the water pump of the slave machine is prolonged, and the stability and reliability of the system are enhanced; in addition, the running frequency difference of the master machine and the slave machine is not large, and the master machine and the slave machine are basically synchronous although time delay exists, so that the effect of running all the water pumps of the multi-pump system at the same speed can be achieved, and the efficiency of the system is improved.
Example 3
In the multi-pump parallel photovoltaic pumping system, when the specifications of all the water pumps in a plurality of groups of photovoltaic water pumps connected in parallel are consistent, a better control effect can be achieved. The above embodiments 1 and 2 have been described with reference to the case where the specifications of the water pumps are the same. The control method of the multi-pump parallel photovoltaic pumping system does not limit the specifications of the water pumps, and can still realize better control effect when the specifications of the water pumps are inconsistent. Examples are as follows:
according to the theoretical relation of the cubic linear correlation of the centrifugal water pump power and the frequency: power P ═ k ═ F of water pump3And k is different according to different specifications of the water pump, and F is the operating frequency of the water pump. Assuming that the specifications of all water pumps in the photovoltaic pumping system are inconsistent, when a slave water pump needs to be added for operation, the target value of the operation frequency of the slave is measuredThe calculation formula is shown in formula 5:
Fs＝sqrt3((P0+P1+…+PN)/(P0+P1+…+PN+1))*F0formula 5
Wherein N is the number of the slave water pumps currently running in the photovoltaic pumping system, P0For the power of the main water pump, P1，P2，…，PN，PN+1Respectively, the power of the slave water pumps 1, 2 …, N + 1.
From equation 5, it can be seen that when the power specifications of the water pumps are consistent, i.e. k of the water pumps are the same, the master water pump and the slave water pump both operate at the rated frequency F when the pumps are increased0And with the increased illumination and the increased photovoltaic input power, the master water pump and the slave water pump are kept at the rated frequency F0So that the power of the individual pumps is the same, P0＝P1＝P2＝…＝PN＝PN+1Target value F of the operating frequency of the slavesCan be simplified to Fs＝sqrt3((N+1)/(N+2))F0This is the same as formula 1 in examples 1 and 2.
When the water pump of one slave machine needs to be shut down, the target value F of the running frequency of the slave machine at the momentsThe calculation formula of (d) is shown in formula 6:
Fs＝sqrt3((P0+P1+…+PN)/(P0+P1+…+PN-1))*F0(N.gtoreq.1) formula 6
Wherein N is the number of the slave water pumps currently running in the photovoltaic pumping system, P0For the power of the main water pump, P1，P2，…，PN-1，PNRespectively the power of the slave water pumps 1, 2 …, N-1, N.
It can be seen from equation 6 that when the power specifications of the water pumps are consistent, that is, k of the water pumps are the same, the slave water pump operates at the lowest effective water outlet frequency when the pumps are reduced, and the host operates in the maximum power tracking mode, and the operating frequency of the host is adjusted in real time as the light intensity decreases and the photovoltaic input power decreasesIn addition, the frequency delay synchronous regulation mechanism is that the difference between the running frequencies of the master machine and the slave machine is larger than a hysteresis frequency value FbandThe frequency of the master and the slave are not completely consistent when the pump is reduced, so that the power of the slave is k x Fst 3The power of the main machine is k x Fmt 3Obtaining the target value F of the running frequency of the slave machine after pump reductionsIs calculated by the formula Fs’＝sqrt3((N*Fst 3+Fmt 3) /N), wherein N is more than or equal to 1, N is the number of the slave water pumps currently running in the photovoltaic pumping system, and FmtFor the current operating frequency of the main engine water pump, FstThe current running frequency of the water pump of the slave machine. That is, the same as formula 2 in example 1 and example 2.
It should be noted that, when the rated operating parameters of each water pump in the photovoltaic pumping system are not consistent, if the rated powers are different, the water pump with the larger rated power and the corresponding power inverter are selected as the host, so that the setting is such that when the maximum power tracking algorithm is executed, the power change value caused by the frequency disturbance is relatively larger, which is beneficial to correctly judging the photovoltaic maximum power tracking direction, and at this time, even if the formula 1 and the formula 2 are adopted to calculate the operating frequency of the slave, the system can still stably and efficiently operate. This is because, although the slave operation frequency obtained by the equations 1 and 2 may cause a large error due to the inconsistency of the power specifications of the water pumps, the master operates in the normal pressure control mode, so that it is ensured that the system after the slave is increased or decreased stably operates at the maximum power point. Meanwhile, although the operation frequency of the slave computer is calculated by the formulas 1 and 2, the frequency difference between the master computer and the slave computer is relatively large, the frequency difference is rapidly reduced by a frequency delay synchronization mechanism, and the system can still stably operate.
Referring to fig. 5, fig. 5 is a diagram illustrating the effect of the control method of the multi-pump parallel photovoltaic pumping system according to the present invention when the specifications of the water pumps in the photovoltaic pumping system are consistent. The photovoltaic pumping system corresponding to the figure 5 adopts three same models (rated specification: power 750W, flow 12 m)3H, lift 11m) are connected in parallel and placed in a poolThe pond is connected with three water raising pipes with the same caliber (the inner diameter is 57mm) under water, the net lift is 6.5m, the flow of each water pump is monitored by three flow meters on a high platform, and the water raising pipes are converged into a main water pipe with the inner diameter of 83 mm; each water pump is driven by a special inverter, and the photovoltaic input ends of the three inverters are connected in parallel to a 2.4kW analog photovoltaic array. The photovoltaic simulation power curve of the photovoltaic pumping system under the cloudy weather condition is shown in fig. 5a, fig. 5b and fig. 5c are actually measured curves of output power and water pump flow respectively, and it can be seen that the comprehensive photovoltaic power generation efficiency is more than 99%, which shows that the photovoltaic pumping system can rapidly respond to the change of solar irradiance and accurately control in real time, and experimental data verifies the high efficiency and stability of the control method of the embodiment of the invention.
Referring to FIG. 6, FIG. 6 is a comparative test chart of water pumping effect when a three-pump system and a single-pump system are operated, and the three-pump system in FIG. 6 is the system in the embodiment shown in FIG. 5, i.e. three identical models (rated specification: 750W power, 12m flow rate)3H, 11m) are connected in parallel, the medium-efficiency high-power single pump in fig. 6 is a centrifugal pump with larger power, and the power and specification of the centrifugal pump are the sum of the power and flow specifications of the three water pumps in the embodiment shown in fig. 5, namely the rated specification is as follows: the power is 2.2kW, and the flow rate is 36m3H, lift 11 m. During testing, the three-pump system and the single-pump system are driven by the same 2.4kW analog photovoltaic array connected to one inverter.
The test result shown in fig. 6 is obtained by simulating the lighting condition in the morning on a fine day and comparing and testing the water lifting effects of the three-pump system and the single-pump system, and as can be seen from fig. 6, the three-pump system can effectively operate and lift water when lower photovoltaic power is input compared with the single-pump system, so that the photovoltaic energy utilization rate of the whole day is improved; meanwhile, in the three pump systems, the same operation frequency is adopted by each water pump, the total water lifting amount is higher than the condition of operation at different speeds, and the conclusion that the operation efficiency of each water pump at the same speed is higher is verified.
Example 4
The present embodiment provides an inverter, which includes a memory and a processor, where the memory stores a computer program, and when the computer program is executed by the processor, the processor implements the method for controlling the multi-pump parallel photovoltaic pumping system as shown in embodiments 1 to 3.
Example 5
The embodiment provides a monitor, which is connected with a master inverter and a slave inverter, receives own operating frequency information uploaded by the master inverter and the slave inverter, controls the switching of the operating mode of the master inverter according to the received operating frequency information, controls the starting or the closing of the slave, and adjusts the operating frequency. Specifically, when the operating frequency of the master water pump is greater than or equal to a first preset frequency, the monitor calculates the operating frequency of the slave and sends an operating instruction carrying the operating frequency of the slave to one of the slave inverters, and the monitor controls the master inverter to switch to a normal-pressure control mode; similarly, when the operating frequencies of the master water pump and the slave water pumps are less than or equal to a second preset frequency, the monitor calculates the operating frequency of the slave, sends a stop instruction to one slave inverter in operation, sends an instruction carrying the operating frequency of the slave to the remaining slave inverters in operation, and controls the master inverter to switch to the normal pressure control mode.
In addition, the monitor is also used for determining one of the photovoltaic water pumps as a host of the photovoltaic water pump according to the running time of each set of photovoltaic water pump so as to realize the running time balance of each set of photovoltaic water pump. For example: when the multi-pump parallel photovoltaic pumping system is provided with 4 sets of photovoltaic water pumps with consistent specifications, which are respectively numbered as 1, 2, 3 and 4, in order to achieve the purposes of balancing the running time of each water pump and prolonging the service life of the whole system, the monitor can periodically select one of the photovoltaic water pumps according to the serial number as a host, the rest of the photovoltaic water pumps are used as slaves, for example, a month is used as a cycle, the photovoltaic water pump with the serial number of 1 is selected as the host when the running time is less than 1 month, and the photovoltaic water pumps with the serial number of 2 are used as the host when the running time is 2 months, so that the running time of each water pump is sequentially switched, and the running time of each water pump is guaranteed to be balanced. Of course, the switching may be performed manually by the user.
Example 6
The embodiment provides a multi-pump parallel photovoltaic pumping system which comprises a set of photovoltaic array and at least two sets of photovoltaic pumps arranged in parallel. Each group of photovoltaic water pumps comprises an inverter and a corresponding water pump. When the photovoltaic pumping system works, one of the photovoltaic water pumps serves as a photovoltaic water pump host, the other photovoltaic water pumps serve as photovoltaic water pump slaves, the photovoltaic water pump host and the photovoltaic water pump slaves can communicate with each other, and instructions such as starting, stopping and operating frequency of the slaves are given by the host. For convenience of description later, an inverter in a master of the photovoltaic water pump is referred to as a master inverter, a water pump is referred to as a master water pump, and an inverter in a slave of the photovoltaic water pump is referred to as a slave inverter and a water pump is referred to as a slave water pump. Among them, the master inverter is the inverter in embodiment 4, which can realize the control method shown in embodiments 1 to 3.
In a possible embodiment, the individual water pumps are of uniform size, with the same power rating, flow rate and head. And the master and slave identities of the photovoltaic water pump master and the photovoltaic water pump slave can be switched according to a preset rule, if the photovoltaic pumping system has 4 sets of photovoltaic water pumps with consistent specifications, which are respectively numbered as 1, 2, 3 and 4, in order to realize the purpose of balancing the running time of each water pump and prolonging the whole running life of the system, one of the water pumps can be selected as the master according to the serial periodicity of the photovoltaic water pump numbers, the rest of the water pumps can be used as the slave, for example, the water pump with the serial number of 1 is selected as the master when the running time is less than 1 month, and the water pumps with the serial number of 2 are used as the master when the running time is 2 months, so that the running time of each water pump is guaranteed to be balanced. Of course, the switching may be performed manually by the user.
In other feasible embodiments, when the specifications of the water pumps are not consistent, the photovoltaic water pump with larger power is selected as the host, and by the arrangement, when the maximum power tracking algorithm is executed, the power change value caused by frequency disturbance is relatively larger, which is beneficial to correctly judging the photovoltaic maximum power tracking direction, and at the moment, even if the running frequency of the slave is calculated by adopting the formula 1 and the formula 2, the system can still stably and efficiently run.
Example 7
The embodiment provides a multi-pump parallel photovoltaic pumping system, which comprises a photovoltaic array, at least two sets of photovoltaic water pumps connected in parallel and a monitor, wherein one photovoltaic water pump is a photovoltaic water pump host, the rest photovoltaic water pumps are photovoltaic water pump slaves, the photovoltaic water pump host comprises a host inverter and a host water pump, the photovoltaic water pump slaves comprise a slave inverter and a slave water pump, and the monitor is connected with the host inverter and the slave inverter, wherein the monitor is the monitor shown in embodiment 5.
Example 8
The present embodiment provides a computer-readable storage medium, on which the control method of the multi-pump parallel photovoltaic pumping system is stored, and when being executed by a processor, the control method of the multi-pump parallel photovoltaic pumping system implements the control method of the multi-pump parallel photovoltaic pumping system as shown in embodiments 1 to 3 above.
Since the specific embodiment of the computer-readable storage medium of this embodiment is substantially the same as the embodiments of the payment method for the photovoltaic pumping system, further description is omitted here.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (10)

1. A control method of a multi-pump parallel photovoltaic pumping system is characterized in that the multi-pump parallel photovoltaic pumping system comprises a photovoltaic array and at least two sets of photovoltaic water pumps which are connected in parallel, wherein one photovoltaic water pump is a photovoltaic water pump host, the rest photovoltaic water pumps are photovoltaic water pump slave machines, the photovoltaic water pump host comprises a host inverter and a host water pump, the photovoltaic water pump slave machines comprise a slave inverter and a slave water pump, and the control method comprises the following steps:
when the host inverter is powered on and operates, the operating frequency of the host water pump is adjusted through a maximum power tracking mode;
when the operating frequency of the master water pump is greater than or equal to a first preset frequency, an operating instruction carrying a slave operating frequency target value is sent to one of the slave inverters to control the corresponding slave water pump to start, and the master inverter is switched to a normal pressure method control mode;
when the operating frequency of the master water pump and the slave water pumps is less than or equal to a second preset frequency, sending a stop instruction to one of the slave inverters in operation, and sending an instruction carrying a slave operating frequency target value to the remaining slave inverters in operation to control and adjust the operating frequency of the corresponding slave water pump, wherein the master inverter is switched to a normal pressure method control mode;
and when the running frequency of the water pump of the slave machine reaches the target value of the running frequency of the slave machine, the host machine inverter is switched from the normal-pressure control mode to the maximum power tracking mode, and the running frequency of the water pump of the slave machine is synchronously adjusted.
2. The method of claim 1 for controlling a multi-pump parallel photovoltaic lift system,
when the operating frequency of the master water pump is greater than or equal to a first preset frequency, the master inverter executes the step of sending an operating instruction carrying a target value of the operating frequency of the slave to one of the slave inverters;
and when the operating frequency of the master water pump and the slave water pump is less than or equal to a second preset frequency, the master inverter executes the step of sending a stop instruction to one of the slave inverters in operation and sending an instruction carrying a slave operating frequency target value to the rest slave inverters in operation.
3. The method of controlling a multi-pump parallel photovoltaic pumping system according to claim 1, further comprising a monitor connected to the master inverter and the slave inverter;
when the running frequency of the main machine water pump is greater than or equal to a first preset frequency, the monitor executes the step of sending a running instruction carrying a target value of the running frequency of the slave machine to one of the slave machine inverters, and the monitor controls the main machine inverter to be switched to a normal pressure method control mode;
when the operating frequency of the master water pump and the operating frequency of the slave water pumps are less than or equal to a second preset frequency, the monitor executes the step of sending a stop instruction to one of the slave inverters in operation and sending an instruction carrying a slave operating frequency target value to the remaining slave inverters in operation, and the monitor controls the master inverter to be switched to a normal-pressure control mode.
4. The method of claim 3, wherein the monitor is further configured to determine one of the at least two sets of photovoltaic pumps connected in parallel as a host of the at least two sets of photovoltaic pumps according to an operation time of each set of photovoltaic pumps, so as to achieve operation time equalization of each set of photovoltaic pumps.
5. The method for controlling a multi-pump parallel photovoltaic lift system according to any of claims 1 to 4, wherein said synchronously adjusting the operating frequency of the slave water pumps is specifically:
and adjusting the running frequency of the water pump of the slave machine by adopting a frequency delay synchronization mechanism.
6. The method for controlling a multi-pump parallel photovoltaic pumping system according to claim 5, wherein the step of adjusting the operating frequency of the slave water pumps by using a frequency delay synchronization mechanism comprises the steps of:
acquiring the current running frequency of a host water pump and the running frequency of a slave water pump;
when the operating frequency of the master water pump is smaller than the rated frequency and the difference between the operating frequency of the master water pump and the operating frequency of the slave water pump is larger than a set hysteresis frequency value, calculating an updated value of the operating frequency of the slave water pump and adjusting the operating frequency of the slave water pump to the updated value of the operating frequency of the slave, wherein the calculation method of the updated value of the operating frequency of the slave is as follows:
Fs’＝sqrt3((N*Fst 3+Fmt 3)/(N+1)) if(|Fmt-Fst|≥Fband) (N≥1)
when the running frequency of the master water pump reaches the rated frequency, accumulating preset component values delta F at fixed time to calculate an updated value of the running frequency of the slave water pump, and adjusting the running frequency of the slave water pump to the updated value of the running frequency of the slave, wherein the method for calculating the updated value of the running frequency of the slave is as follows:
Fs’＝Fst+ΔF if(Fmt＝F0，(Fmt-Fst)<Fband)
wherein, F0Is the rated frequency of the main engine water pump, Fs' updating the value for the slave operating frequency, FmtFor the current operating frequency of the main engine water pump, FstThe current operation frequency of the slave water pumps, N the number of the current operation slave water pumps, FbandAnd setting a hysteresis frequency value for the reference value.
7. Method for controlling a multi-pump parallel photovoltaic lift system according to one of the claims 1 to 4,
when a water pump of a slave machine is started, the calculation method of the target value of the running frequency of the slave machine comprises the following steps:
Fs＝sqrt3((N+1)/(N+2))F0
when one slave water pump is shut down, the calculation method of the slave operation frequency target value comprises the following steps:
Fs＝sqrt3((N*Fst 3+Fmt 3)/N)
where N is the number of currently operating slave water pumps, F0Rated frequency of the main engine water pump, FmtFor the current operating frequency of the main engine water pump, FstFor the current slave pump operating frequency, FsIs the target value of the running frequency of the slave machine.
8. An inverter, comprising a memory and a processor, wherein the memory has stored thereon a computer program, which, when executed by the processor, causes the processor to carry out a method of controlling a multi-pump parallel photovoltaic lift system according to any of claims 1 to 7.
9. The multi-pump parallel photovoltaic pumping system is characterized by comprising a photovoltaic array and at least two sets of photovoltaic water pumps connected in parallel, wherein one photovoltaic water pump is a photovoltaic water pump host, the rest photovoltaic water pumps are photovoltaic water pump slave machines, the photovoltaic water pump host comprises a host inverter and a host water pump, the photovoltaic water pump slave machines comprise slave inverter and slave water pumps, and the host inverter is the inverter according to claim 8.
10. The multi-pump parallel photovoltaic pumping system is characterized by comprising a photovoltaic array, at least two sets of photovoltaic water pumps connected in parallel and a monitor, wherein one photovoltaic water pump is a photovoltaic water pump host, the rest photovoltaic water pumps are photovoltaic water pump slave machines, the photovoltaic water pump host comprises a host inverter and a host water pump, the photovoltaic water pump slave machines comprise a slave inverter and a slave water pump, the monitor is connected with the host inverter and the slave inverter, and the monitor is used for realizing the control method of the multi-pump parallel photovoltaic pumping system according to any one of claims 3 to 7.
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