Disclosure of Invention
Aiming at the defects existing in the prior art, the invention provides the agricultural light complementary system, which can effectively solve the problems that the agricultural light complementary system is difficult to monitor and analyze the abnormal power generation efficiency and intelligently control the electric quantity of the storage battery, so that the efficiency of the photovoltaic power generation system is poor in the prior art.
In order to achieve the above purpose, the invention is realized by the following technical scheme:
the invention provides an agricultural light complementary system, which at least comprises a plurality of photovoltaic power generation plates and a grid-connected power generation system with a storage battery, wherein a battery management system is arranged between the photovoltaic power generation plates and the storage battery, and the area where the photovoltaic power generation plates are installed is recorded as an installation area, and the agricultural light complementary system further comprises an efficiency evaluation module, an output regulation and control module and a coverage analysis module:
The efficiency evaluation module is used for periodically monitoring and analyzing the power generation efficiency of all the photovoltaic power generation panels, selecting one of the power generation efficiency and the power generation efficiency as a target photovoltaic panel for comparison, monitoring the change of the intensity value of solar radiation received by the target photovoltaic panel, calculating the power generation efficiency corresponding to the target photovoltaic panel at the moment of highest intensity value of solar radiation, combining the power generation efficiency of all the photovoltaic power generation panels for analysis and comparison, and judging whether the working state of all the photovoltaic power generation panels is abnormal;
The output control module comprises an output prediction unit and an output control unit, the output prediction unit performs screening according to the historical working condition of the photovoltaic power generation plate, selects proper working condition and combines the power generation efficiency of the photovoltaic power generation plate to perform analysis and calculation to obtain ideal output power, and the output control unit adjusts the output relation between the photovoltaic power generation plate and the storage battery according to weather conditions and the ideal output power within a certain time range in the future to control the storage capacity of the storage battery;
The coverage analysis module is used for dynamically monitoring and analyzing the power generation efficiency of the photovoltaic power generation plate, calculating the power abnormal value of the photovoltaic power generation plate according to the use time of the photovoltaic power generation plate, generating a surface coverage abnormal signal when the power abnormal value exceeds a preset range, and cleaning dust on the surface of the corresponding photovoltaic power generation plate.
Further, the efficiency evaluation module compares the analysis process specifically as follows:
the method comprises the steps of firstly, obtaining the effective area of each photovoltaic power generation plate, obtaining rated power of the photovoltaic power generation plate, obtaining sunrise time and sunset time of a mounting area every day, and recording a time interval from sunrise time to sunset time as a monitoring duration interval;
Secondly, in a monitoring time interval, marking one photovoltaic power generation plate as a target photovoltaic plate, acquiring a solar radiation intensity value of the surface of the target photovoltaic plate in real time, acquiring a current environment temperature value in real time, acquiring output current and output voltage of each photovoltaic power generation plate in real time, calculating the product of the output current and the output voltage, and marking the product as output power;
Extracting a maximum value of solar radiation intensity values in a last complete monitoring time interval and an environmental temperature value T MAX at a corresponding moment, marking the maximum value of the solar radiation intensity values as a radiation maximum value I MAX, extracting the maximum value of output power of each photovoltaic power generation plate in the last complete monitoring time interval as an output maximum value P i OUT, and marking the output power of a target photovoltaic plate at the corresponding moment of the extracted radiation maximum value as a target power P real, wherein I represents the serial number of each photovoltaic power generation plate;
Substituting the environmental temperature value T MAX, the radiation maximum value I MAX and the rated power P STC of the photovoltaic power generation panel into a formula The method comprises the steps of obtaining a theoretical power maximum value P MAX of a target photovoltaic panel, wherein alpha is a preset temperature coefficient and represents the relative change percentage of the output power of the photovoltaic panel when each degree centigrade changes, I STC is the illumination intensity under the standard test condition, T STC is the temperature of the panel under the standard test condition, and substituting the target power P real and the theoretical power maximum value P MAX of the target photovoltaic panel into a formula XL BZ=Preal/PMAX for calculation to obtain the standard maximum efficiency XL BZ;
step five, extracting the output maximum value and the corresponding recording time of the target photovoltaic panel, comparing the output maximum value with the target power P real and the corresponding recording time, and if the power values are the same and the corresponding recording time is consistent, entering step six, otherwise, generating a recording abnormal signal and sending the recording abnormal signal to a handheld terminal of a worker;
Step six, through the formula Calculating the maximum efficiency XL i of each photovoltaic power generation plate, wherein the maximum efficiency of the target photovoltaic power generation plate is the standard maximum efficiency of the target photovoltaic power generation plate, calculating the difference between the maximum efficiency XL i of each photovoltaic power generation plate and the standard maximum efficiency XL BZ, recording the difference as an efficiency deviation, presetting an efficiency difference threshold, comparing the efficiency deviation of each photovoltaic power generation plate with the efficiency difference threshold, generating a stable output signal when the efficiency deviation and the efficiency difference threshold are smaller than or equal to the efficiency difference threshold, generating a stable abnormal signal when the efficiency deviation and the efficiency difference threshold are larger than the efficiency difference threshold, marking the photovoltaic power generation plate as abnormal, and simultaneously transmitting the serial numbers of all the photovoltaic power generation plates in abnormal states to a handheld terminal of a worker
Further, obtaining the absolute value of the efficiency deviation of each photovoltaic power generation plate, marking the photovoltaic plate with the absolute value of the efficiency deviation larger than the efficiency difference threshold as a problem photovoltaic plate, subtracting the standard maximum efficiency XL BZ from the measurement maximum efficiency XL i of the problem photovoltaic plate, marking the problem photovoltaic plate as an abnormal photovoltaic plate if the result is larger than 0, counting the number of the abnormal photovoltaic plates, generating an abnormal signal of the target photovoltaic plate when the number of the abnormal photovoltaic plates is larger than or equal to a preset number threshold, simultaneously calculating the measurement maximum efficiency average value of all the abnormal photovoltaic plates as the standard maximum efficiency, and repeating the step six
Further, the output prediction unit obtains the maximum efficiency and the efficiency deviation of each photovoltaic power generation plate obtained by the last monitoring, when the efficiency deviation of all the photovoltaic power generation plates is smaller than or equal to the efficiency difference threshold, the minimum value in all the maximum efficiency is extracted and is recorded as an efficiency prediction value XL min, the minimum value of the total annual direct solar radiation intensity in the installation area is obtained and is recorded as a radiation standard value, a change curve of the solar radiation intensity value in each monitoring duration interval along with time is recorded as a radiation intensity change graph, and the radiation intensity change graph in the last month is extracted and is screened;
drawing a straight line represented by a radiation standard value in a radiation intensity change graph, calculating the projection length of a part of the radiation intensity change graph, which is positioned above the straight line, on a time axis to be recorded as effective duration when the straight line is intersected with the radiation intensity change graph, dividing the effective duration by the total duration of a corresponding monitoring duration interval to obtain an effective duty ratio, setting an effective duty ratio threshold, and recording the corresponding radiation intensity change graph as an ideal intensity change graph when the effective duty ratio is greater than or equal to the effective duty ratio threshold;
Calculating the average value of the solar radiation intensity values in the ideal intensity change diagram to be recorded as an ideal intensity value I HP, obtaining the average temperature T HP on the same day, and substituting the average temperature T HP into a formula And (3) calculating to obtain the ideal output power OP MAX.
Further, the output regulation unit obtains the ideal output power OP MAX, sets a future time interval, and the time length T of the future time interval has a calculation formula ofWherein the method comprises the steps ofRepresenting that is not greater thanW all、We respectively represents the total electric quantity of the storage battery and the daily electric quantity of the electric facilities, the weather conditions of each day in a future time interval of the installation area are obtained, the weather is respectively divided into two types of sunny days and non-sunny days according to the weather conditions, and a proper electric storage ratio is preset;
When all the time intervals in the future are sunny days, the storage capacity of the storage battery is adjusted to be the total storage capacity multiplied by a proper storage ratio;
when part of sunny days exist in the future time interval, calculating the time difference of the last sunny day from the time of the day to be recorded as T', charging the storage battery and controlling the charging time, wherein the charging time calculation formula is as follows Wherein W NOW and W' respectively represent the current storage capacity and the storage capacity in a state with a proper storage ratio, and the charging is continued until the storage battery is full or the charging duration is over;
And when the sunny day does not exist in the future time interval, controlling to fully charge the storage battery.
Further, the coverage analysis module analyzes the following steps:
Obtaining the measured maximum efficiency recorded for the first time after the installation of each photovoltaic power generation plate is completed and recording the measured maximum efficiency of each photovoltaic power generation plate which is monitored for the last time as the current efficiency XL i N, calculating the time interval between the current time and the installation completion time and recording the working time length t, substituting the time interval into a formula UX=XL i Z*(1-t*k)-XLi N for calculation, wherein k is a preset time length influence coefficient, obtaining a power abnormal value UX, presetting a power abnormal threshold value, generating a surface coverage abnormal signal when the power abnormal value is larger than or equal to the power abnormal threshold value, cleaning and dedusting the surface of the photovoltaic power generation plate, recording the recalculated power abnormal value as UX', and generating a corresponding photovoltaic plate abnormal signal if the power abnormal value is still larger than or equal to the power abnormal threshold value.
Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects:
1. According to the efficiency evaluation module, the target photovoltaic panel is used as a power generation efficiency standard, and the error degree between the power generation efficiency of all the photovoltaic power generation panels and the standard reference is determined through the comparison process, so that the maximum power generation efficiency of the photovoltaic power generation panels installed simultaneously in the same working environment is consistent, even if errors exist, the maximum power generation efficiency is within a set error range, otherwise, the photovoltaic power generation panels can be judged to have functional faults, and therefore the photovoltaic power generation panels with abnormal power generation efficiency can be distinguished rapidly, and the photovoltaic power generation system is convenient for workers to carry out targeted overhaul and maintenance and is beneficial to guaranteeing the power generation efficiency.
2. According to the invention, the daily sunshine duration under a relatively good illumination condition is screened out by dynamically analyzing the daily solar radiation intensity variation value in the last month, so that the sunshine duration under the condition of full sunshine in one day is screened out according to the length of the sunshine duration, the current ideal output power can be obtained by analysis, the power generation efficiency of the photovoltaic power generation panel is conveniently predicted, in addition, the power flow direction of the photovoltaic power generation panel is controlled to charge the storage battery according to different weather conditions in the future, and the charging time and the charging amount are intelligently adjusted, so that the electric quantity of the storage battery is in a proper electric quantity range in daily use, the service life of the storage battery is prolonged as far as possible, the storage battery can be prevented from supplying power to facilities when the photovoltaic power generation panel cannot generate electric energy, the generated electric energy is fully utilized, and the electric quantity storage of the storage battery is reasonably planned.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention is further described below with reference to examples.
Referring to fig. 1, the agricultural light complementary system at least comprises a plurality of photovoltaic power generation plates and a grid-connected power generation system with a storage battery, wherein the photovoltaic power generation plates absorb solar energy to generate electric energy, the grid-connected power generation system outputs the electric energy into the storage battery in a direct current mode or is integrated into a national power grid through an inverter, a Battery Management System (BMS) for adjusting charging current and stabilizing voltage is arranged between the photovoltaic power generation plates and the storage battery, an area where the photovoltaic power generation plates are installed is recorded as an installation area, and the agricultural light complementary system further comprises an efficiency evaluation module, an output regulation module and a coverage analysis module.
The efficiency evaluation module monitors the power generation efficiency of all the photovoltaic power generation panels, selects one of the photovoltaic power generation panels as a target photovoltaic panel for comparison, and analyzes whether the working states of all the photovoltaic power generation panels are abnormal according to the power generation efficiency of the target photovoltaic panel.
The comparison analysis process specifically comprises the following steps of firstly, obtaining the effective area of each photovoltaic power generation plate (the effective area refers to the surface area of a solar panel capable of converting solar energy into electric energy on the photovoltaic power generation plate, and does not comprise a fixed frame on the periphery of the solar panel), obtaining the rated power of the photovoltaic power generation plate (the rated power refers to the solar radiation intensity of 1000W/m 2, the environmental temperature of 25 ℃ and the power generation power under the spectral distribution condition of AM1.5 of the unit area of the photovoltaic power generation plate under the standard test condition), obtaining the sunrise time and the sunset time of each day of an installation area (which can be obtained through meteorological data of a local weather table), recording the time interval from the sunrise time to the sunset time as a monitoring time interval, and avoiding monitoring invalid data through the current monitoring interval, and improving the monitoring efficiency;
In a monitoring time interval, acquiring the solar radiation intensity value of the right angle of one photovoltaic power generation plate in real time, recording the photovoltaic power generation plate as a target photovoltaic plate (the solar radiation intensity value can be directly measured by a solar radiation measuring instrument in the prior art, the solar radiation intensity value of the right angle can be measured by installing the measuring instrument on the target photovoltaic plate), acquiring the current environment temperature value in real time, acquiring the output current and the output voltage of each photovoltaic power generation plate in real time, calculating the product of the output current and the output voltage, and recording the product as the output power;
Extracting a maximum value of solar radiation intensity values in a last complete monitoring time interval and an environmental temperature value T MAX at a corresponding moment, marking the maximum value of the solar radiation intensity values as a radiation maximum value I MAX, extracting the maximum value of output power of each photovoltaic power generation plate in the last complete monitoring time interval as an output maximum value P i OUT, and marking the output power of a target photovoltaic plate at the corresponding moment of the extracted radiation maximum value as a target power P real, wherein I represents the serial number of each photovoltaic power generation plate;
It should be noted that, the photovoltaic power generation panels in the single agricultural and optical complementary power station are generally installed in a centralized manner, that is, hardware data parameters of the photovoltaic power generation panels are kept consistent, and the installation positions of the photovoltaic power generation panels are all in the same sun irradiation area, so that the maximum value of the solar radiation intensity value corresponding to the single photovoltaic power generation panel can be used as the maximum value of the solar radiation intensity value absorbed by each photovoltaic power generation panel under the condition of not being influenced by external factors, and the environmental temperature of each photovoltaic power generation panel can be considered to be the same under the condition of not being influenced by other factors in the same area.
Substituting the environmental temperature value T MAX, the radiation maximum value I MAX and the rated power P STC of the photovoltaic power generation panel into a formulaThe theoretical power maximum value P MAX of the target photovoltaic panel is obtained, wherein alpha is a preset temperature coefficient and represents the relative change percentage (%/DEGC) of the output power of the photovoltaic panel when the temperature changes every DEG C, the relative change percentage is generally provided by manufacturers, I STC is the illumination intensity under the standard test condition (W/m 2);TSTC is the temperature of the panel under the standard test condition, usually 25 ℃, and the target power P real and the theoretical power maximum value P MAX of the target photovoltaic panel are substituted into a formula XL BZ=Preal/PMAX for calculation to obtain the standard maximum efficiency XL BZ;
Step five, extracting the output maximum value and the corresponding recording time of the target photovoltaic panel, comparing the output maximum value with the target power P real and the corresponding recording time, and if the power values are the same and the corresponding recording time are the same, entering step six, otherwise, generating a recording abnormal signal and sending the recording abnormal signal to a handheld terminal of a worker, and checking the target photovoltaic panel and the corresponding recording time by the worker;
It should be noted that, under normal conditions, the time when the power generated by the photovoltaic power generation panel is highest should correspond to the time when the intensity of the solar radiation received by the photovoltaic power generation panel is greatest, because the time when the intensity of the solar radiation is greatest is corresponding to the more solar energy absorbed by the photovoltaic power generation panel, the higher the output power is.
Step six, through the formulaCalculating the maximum efficiency XL i of each photovoltaic power generation plate, wherein the maximum efficiency of the target photovoltaic power generation plate is the standard maximum efficiency, calculating the difference between the maximum efficiency XL i of each photovoltaic power generation plate and the standard maximum efficiency XL BZ, recording the difference as an efficiency deviation, presetting an efficiency difference threshold, comparing the efficiency deviation of each photovoltaic power generation plate with the efficiency difference threshold, generating a stable output signal when the efficiency deviation and the efficiency difference threshold are smaller than or equal to the efficiency difference threshold, generating a stable abnormal signal when the efficiency deviation and the efficiency difference threshold are larger than the efficiency difference threshold, marking the photovoltaic power generation plate as abnormal, and simultaneously transmitting the serial numbers of all the photovoltaic power generation plates in abnormal states to the handheld terminal of staff.
The target photovoltaic panel is used as a power generation efficiency standard, the error degree between the power generation efficiency of all the photovoltaic power generation panels and the standard reference is determined through the comparison process, and because the maximum power generation efficiency of the photovoltaic power generation panels installed simultaneously under the same working environment is kept consistent, even if errors exist, the maximum power generation efficiency is within a set error range, otherwise, the photovoltaic power generation panels can be judged to have functional faults, so that the photovoltaic power generation panels with abnormal power generation efficiency can be rapidly distinguished, and the system is convenient for workers to carry out targeted overhaul and maintenance, and is favorable for guaranteeing the power generation efficiency.
Further, obtaining an absolute value of the efficiency deviation of each photovoltaic power generation plate, marking the photovoltaic plates with the absolute values of the efficiency deviations larger than the efficiency difference threshold as problem photovoltaic plates, subtracting the standard maximum efficiency XL BZ from the measurement maximum efficiency XL i of the problem photovoltaic plates, marking the problem photovoltaic plates as abnormal photovoltaic plates if the result is larger than 0, counting the number of the abnormal photovoltaic plates, when the number of the abnormal photovoltaic plates is larger than or equal to a preset number threshold (in a specific embodiment, the number threshold is equal to the total number of the photovoltaic power generation plates multiplied by 5%), generating a target photovoltaic plate abnormal signal, overhauling and maintaining the target photovoltaic plates by staff, calculating the measurement maximum efficiency average value of all the abnormal photovoltaic plates as the standard maximum efficiency, and repeating the step six.
The output control module comprises an output prediction unit and an output control unit, the output prediction unit screens according to the historical working condition of the photovoltaic power generation plate, selects proper working condition to analyze and calculate the power generation efficiency of the photovoltaic power generation plate to obtain ideal output power, and the output control unit adjusts the output relation between the photovoltaic power generation plate and the storage battery according to weather conditions and the ideal output power within a certain time range in the future to control the storage capacity of the storage battery.
The output prediction unit obtains the maximum efficiency and the efficiency deviation of each photovoltaic power generation plate obtained by the last monitoring, when the efficiency deviation of all the photovoltaic power generation plates is smaller than or equal to an efficiency difference threshold value, the minimum value in all the maximum efficiency is extracted and recorded as an efficiency prediction value XL min, the minimum value of the total annual direct solar radiation intensity of the installation area (namely the minimum value of the radiation intensity of the target area in the annual range under the condition of direct sunlight, which means the minimum intensity of the radiation of the ground in the condition of direct solar radiation) is obtained and recorded as a radiation standard value, a time change curve of the solar radiation intensity value in each monitoring duration interval is drawn and recorded as a radiation intensity change graph, the radiation intensity change graph in the last month is extracted and screened, and the screening process is as follows:
Drawing a straight line represented by a radiation standard value in a radiation intensity change graph, calculating the projection length of a part of the radiation intensity change graph, which is positioned above the straight line, on a time axis to be recorded as effective duration when the straight line is intersected with the radiation intensity change graph in the radiation intensity change graph, dividing the effective duration by the total duration of a corresponding monitoring duration interval to obtain an effective duty ratio, setting an effective duty ratio threshold value, recording the corresponding radiation intensity change graph as an ideal intensity change graph when the effective duty ratio value is greater than or equal to the effective duty ratio threshold value, and selecting the ideal intensity change graph closest to the current date for further analysis;
Calculating the average value of the solar radiation intensity values in the ideal intensity change diagram to be recorded as an ideal intensity value I HP, obtaining the average temperature T HP on the same day, and substituting the average temperature T HP into a formula And (3) calculating to obtain the ideal output power OP MAX.
The daily sunshine duration under a relatively good illumination condition is screened out by dynamically analyzing the daily solar radiation intensity change value in the last month, so that the sunshine duration under the condition of full sunshine in one day is screened out according to the length of the sunshine duration, and the current ideal output power can be obtained by analysis, thereby being convenient for the subsequent prediction of the power generation efficiency of the photovoltaic power generation panel.
The output regulation and control unit obtains ideal output power OP MAX, a future time length interval is set, and a time length T calculation formula of the future time length interval is as followsWherein the method comprises the steps ofRepresenting that is not greater thanW all、We respectively represents the total electric quantity of the storage battery and the daily electric quantity of electric facilities (including all direct current equipment in the installation area), acquires the weather conditions of each day in the future time interval of the installation area (obtained by weather forecast of a local weather station), respectively classifies the weather into two types of sunny days and non-sunny days according to the weather conditions, and presets a proper electric storage ratio;
When all the time intervals in the future are sunny days, the storage capacity of the storage battery is adjusted to be the total storage capacity multiplied by a proper storage ratio, and the electric quantity of the storage battery is adjusted to be in a proper proportion by controlling charge and discharge, so that the service life of the storage battery is prolonged as much as possible, and the storage effect of the storage battery is ensured;
When part of sunny days exist in the future time interval, calculating the time difference between the latest sunny day and the time of the day to be recorded as T' (taking the day as a unit), charging the storage battery and controlling the charging time, wherein a charging time calculation formula is as follows Wherein W NOW and W' respectively represent the current storage capacity and the storage capacity in a state with a proper storage ratio, and the charging is continued until the storage battery is full or the charging duration is over;
And when the sunny day does not exist in the future time interval, controlling to fully charge the storage battery.
According to different weather conditions in the future, the electric power flow direction of the photovoltaic power generation panel is controlled to charge the storage battery, and the charging time and the charging amount are intelligently adjusted, so that the electric quantity of the storage battery is in a proper electric quantity range during daily use, the service life of the storage battery is prolonged as much as possible, meanwhile, the storage battery can be prevented from supplying power to a facility when the photovoltaic power generation panel cannot generate electric energy, the generated electric energy is fully utilized, and the electric quantity storage of the storage battery is reasonably planned.
The coverage analysis module is used for analyzing and judging abnormal conditions of the photovoltaic power generation plate and generating corresponding abnormal data signals to remind workers of timely cleaning dust on the surface of the photovoltaic power generation plate, so that the power generation efficiency of the photovoltaic power generation plate is improved.
The coverage analysis module analyzes the process specifically as follows:
Obtaining the measured maximum efficiency recorded for the first time after the installation of each photovoltaic power generation panel is completed and recording the measured maximum efficiency of each photovoltaic power generation panel as initial efficiency XL i Z, obtaining the measured maximum efficiency of each photovoltaic power generation panel monitored last time and recording the measured maximum efficiency as current efficiency XL i N, calculating the time interval between the current time and the installation completion time and recording the working time length t, substituting the calculated time interval into a formula UX=XL i Z*(1-t*k)-XLi N to calculate, wherein k is a preset time length influence coefficient, obtaining a power abnormal value UX, presetting a power abnormal threshold value, when the power abnormal value is greater than or equal to the power abnormal threshold value, in a specific embodiment, generating a surface coverage abnormal signal by the power abnormal threshold value of 10%, cleaning and dedusting the surface of the photovoltaic power generation panel (the cleaning and dedusting can be cleaned by a cleaner held by a worker or by mechanical equipment), and recording the recalculated power abnormal value as overhaul' if the power abnormal value is still greater than or equal to the power abnormal threshold value, generating a corresponding photovoltaic panel abnormal signal, and maintaining the corresponding photovoltaic panel by the worker.
It should be noted that, when the power of the photovoltaic power generation panel is abnormally reduced, that is, the reason for non-aging is reduced, the power of the photovoltaic power generation panel is generally reduced by more than 10% due to the coverage of dust, so that the power reduction condition of the photovoltaic power generation panel is analyzed, workers can be helped to find the condition that the photovoltaic power generation panel is covered by dust in time, the photovoltaic power generation panel is convenient to clean by the workers in time, compared with the photovoltaic power generation panel which is regularly cleaned, the efficiency is higher, abnormal signals corresponding to the photovoltaic power generation panel can be generated after the reason for dust coverage is eliminated, the photovoltaic power generation panel which is abnormal in function is convenient to be timely checked by the workers, and the efficiency guarantee of the photovoltaic power generation panel is further optimized and improved.
Although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the foregoing embodiments may be modified or equivalents may be substituted for some of the features thereof, and that the modification or substitution does not depart from the spirit and scope of the embodiments.