CN113507114A - Method for evaluating regulation capacity requirement of power system containing high-proportion renewable energy - Google Patents

Method for evaluating regulation capacity requirement of power system containing high-proportion renewable energy Download PDF

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CN113507114A
CN113507114A CN202110720226.9A CN202110720226A CN113507114A CN 113507114 A CN113507114 A CN 113507114A CN 202110720226 A CN202110720226 A CN 202110720226A CN 113507114 A CN113507114 A CN 113507114A
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photovoltaic
load
power
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electric quantity
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CN113507114B (en
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穆钢
李军徽
刘洪波
李鹤
张哲深
李翠萍
朱星旭
严干贵
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Northeast Electric Power University
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Northeast Dianli University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • 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

Abstract

The method for evaluating the regulation capacity requirement of the power system containing the high-proportion renewable energy comprises the steps of selecting indexes and analyzing the change condition of the photovoltaic permeability in three stages. Has the advantages of scientific and reasonable method, strong applicability, good effect and the like.

Description

Method for evaluating regulation capacity requirement of power system containing high-proportion renewable energy
Technical Field
The invention belongs to the field of peak regulation, and relates to a demand evaluation method for regulating capacity of a power system containing high-proportion renewable energy.
Background
The power system containing the high-proportion renewable energy power supply comprises a traditional thermal power/hydroelectric generating set, a renewable energy generating set represented by photovoltaic/wind power and a load, wherein the photovoltaic/wind power ratio exceeds the installed power supply by more than 20%.
In a traditional power system without photoelectric/wind power renewable energy sources or a power system with low photoelectric/wind power installed ratio, because a traditional power supply is a power supply and is a system regulation capacity provider, the installed capacity and the regulation capacity of the traditional power supply can meet the power/electric quantity requirements of loads, the regulation capacity requirements often do not appear to be insufficient.
The output of the photoelectric/wind power is determined by solar energy, the output of the photoelectric/wind power is random fluctuation and inaccurate and predictive, the attribute of the photoelectric/wind power is a power supply, but the photoelectric/wind power is often regarded as a demand person for system regulation capacity due to the uncertain attribute of the photoelectric/wind power. Under the condition that the load level is not changed, the improvement of the installed proportion of the photoelectric power generator and the wind power generator means that the proportion of a traditional thermal power generator and a traditional hydroelectric power generator set of an adjusting capacity provider in the system is reduced, and the evaluation of the adjusting capacity of the power system containing high-proportion renewable energy sources is obviously related to the multidimensional factors such as the proportion of the renewable energy sources, the fluctuation characteristics of the renewable energy sources, the power/electric quantity of the load fluctuation characteristics and the like.
The value of the demand evaluation of the regulation capacity of the power system containing high-proportion renewable energy sources is as follows: with the rapid growth of photovoltaic power generation systems in local power grids, photovoltaic power generation has become the main power of local power grid power supply. However, the output characteristics of the photovoltaic system are determined by the solar radiation degree and the temperature, and the output characteristics are often greatly different from the requirements of load power and electric quantity. Unlike conventional power systems where the power generation units tend to be the providers of turndown capability, in such high-scale photovoltaic power generation regional power systems, the high-scale photovoltaic power generation access causes the system to have insufficient turndown capability, i.e., the photovoltaic power generation units tend to be the consumers of turndown capability in the system. With the rapid growth of photovoltaic power generation, scientific and reasonable evaluation of the demand of high-proportion photovoltaic power generation on the system regulation capacity is of great importance, so that theoretical guidance can be provided for the energy storage assembly of a regulation capacity provider, and a reference scheme can be provided for the intervention of an auxiliary service market.
Disclosure of Invention
The invention aims to provide a demand evaluation method for regulating capacity of a power system containing high-proportion renewable energy, which is scientific, reasonable, high in applicability and good in effect.
The technical scheme adopted for achieving the purpose of the invention is as follows: a demand evaluation method for regulating capacity of a power system containing high-proportion renewable energy is characterized by comprising the following steps: it comprises the following contents:
1) selecting indexes: drawing a two-dimensional image according to the selected index to describe the matching condition of the claim load and the photovoltaic under a certain configuration, analyzing the regulation capacity requirement under a certain matching condition,
(1) capacity matching rate Vs: the coincidence degree of the area enclosed by the photovoltaic output curve and the load curve;
Figure BDA0003136667150000021
(2) peak to peak ratio Vp: contract rate of absolute values of distances between the peak time moment of the photovoltaic curve and the peak time moment of the load;
Figure BDA0003136667150000022
wherein the peak time of the photovoltaic curve is tPVAnd the peak time of the load curve is tload，|tPV-tloadI is the peak resultant difference;
(3) rate of change of regulating capacity: defining the reduction of the upper limit of the adjusting capacity as a positive value and the increase of the lower limit of the adjusting capacity as a negative value;
reduction rate of upper limit of regulating power
Figure BDA0003136667150000023
Rate of increase of lower limit of regulating power
Figure BDA0003136667150000024
Rate of change of upper and lower limits of regulating power Vi＝Vcap+Vfloor
Wherein
Figure BDA0003136667150000025
Is the annual average value of the load, PminIs the minimum value of the load, PmaxIs the maximum load value;
2) when the photovoltaic permeability changes, the regulation capacity requirement of the load also changes, and the photovoltaic permeability change condition is divided into three stages to be analyzed
First stage
When the photovoltaic permeability is between 0 and 1, for the load, the photovoltaic is in an unsaturated state, all the photovoltaic can be used for supplying power to the load, the photovoltaic output is insufficient, the load needs to be supplied from the outside, namely, the capacity regulation demand part comprises a power demand part and an electric quantity demand part, and the two parts need to be changed along with the change of the photovoltaic permeability;
defining the photovoltaic effective output generation time t1End time t of effective photovoltaic output4Then the photovoltaic supplies the electrical quantity E of the loadPVThe calculation formula (c) is as follows:
Figure BDA0003136667150000026
and the calculation formula of the load demand electric quantity is as follows:
Eload,need＝Eload-EPV
wherein P isPVTo photovoltaic power, EloadFor the total daily power of the load, Eload，needThe target load total electric quantity of the whole day;
when the photovoltaic permeability is less than 1, obviously, the upper limit of the power demand of the load is constant and 1, and the lower limit of the power demand of the load is changed in equal proportion; the photovoltaic permeability changes proportionally according to the load power, and the load power demand is calculated by subtracting the photovoltaic power from the load power, namely, the photovoltaic power changes proportionally;
the load electric quantity demand is changed in proportion to the integral of the area of the photovoltaic permeability because the photovoltaic permeability is changed in proportion;
analyzing the critical condition, and when the maximum photovoltaic power reaches the load power 1, the photovoltaic permeability is 1;
at the moment, the photovoltaic power is completely supplied to the load without any surplus part, and the problem of transferring the photovoltaic power to the power grid is avoided; for the load demand, the load photovoltaic reduction is the power demand under the ideal condition, the integral of each part of the load demand is the electric quantity demand of each time interval, the power demand has no zero crossing point, the electric quantity demand takes the moment when the photovoltaic power reaches the peak value at the certain moment of 11 as a demarcation point, and the electric quantity demand is 8.37 and 8.62 which respectively account for 34.88 percent and 35.92 percent of the load in the whole day; at the moment, the total photovoltaic power requirement amount in the whole day is 16.99, which corresponds to the conclusion and accounts for 70.79% of the load in the whole day, and the upper limit of the power requirement is 1 and the lower limit is 0;
second stage
When the photovoltaic permeability is greater than 1, the upper limit of the power demand of the load still does not change to 1, because no matter how the photovoltaic permeability is increased, the power demand cannot be supplied to the load for a certain time, and the upper limit power demand of the load is not changed; since the photovoltaic permeability is greater than 1, the photovoltaic power is greater than the load power, the photovoltaic power is surplus, the redundant part cannot be supplied with the load and can only be transferred to the power grid, namely, the zero crossing point of the load power demand occurs, the power demand cannot have a negative value, and the lower limit of the load power is 0; in summary, when the photovoltaic permeability is greater than 1, no matter how the photovoltaic permeability increases, the upper limit of the power demand of the load is fixed to 1, and the lower limit is fixed to 0;
the electric quantity demand of the load is mainly analyzed, after the photovoltaic permeability is increased from 1, although the photovoltaic power is still increased in equal proportion, the photovoltaic power is larger than the load power, the power supply increased by the photovoltaic power cannot be sufficient for supplying the load, and the electric quantity demand of the load is not increased in equal proportion any more;
defining four moments under the condition that the photovoltaic permeability is 2, and recording the photovoltaic initial output moment t1Respectively recording two moments with equal photovoltaic and load according to time sequence2And t3And recording the photovoltaic ending output moment as t4；
The photovoltaic permeability is defined as the photovoltaic power supply E at the moment when the photovoltaic permeability is greater than 1PVComprises the following steps:
Figure BDA0003136667150000031
defining the load demand capacity is still:
Eload,need＝Eload-EPV
wherein P isloadIs the load power;
analyzing the electric quantity demand change of the load by combining the condition that the photovoltaic permeability is less than 1; in the change process that increases after photovoltaic permeability is greater than 1, appear when photovoltaic permeability equals 3.44, photovoltaic and load electric quantity self-balancing phenomenon, and then the analysis photovoltaic permeability equals the 3.44 condition:
the photovoltaic permeability is 3.44, and the load power is obtained; due to the fact that the photovoltaic permeability is extended, the photovoltaic power is larger than the load power, the photovoltaic electric quantity is sent back to the power grid, and the time is t2And t3Within the time range; dividing the time of day into 0-t2Period of time, t2-t3Time period and t3-24, in a third period, the first and third periods represent that the power demand and the power demand are greater than zero, respectively, i.e. power and power are required to be obtained from the grid, and the second period represents that the power demand and the power demand are less than zero, i.e. photovoltaic power is surplus and power can be transmitted to the grid; at the moment, the electric quantity demand accumulated values in the three time periods are respectively 6.88, -14.01 and 7.13, the absolute values of the three are respectively 28.67%, 58.38% and 29.71% of the total electric quantity of the load in the whole day, namely, the sum of the first section and the third section is equal to the absolute value of the second section, namely, the surplus electric quantity of the photovoltaic is transferred to the electric quantity in the day through the energy transfer equipmentThe insufficient part can just meet the electric quantity requirement of the whole day, namely, a self-balancing state that the surplus electric quantity of the photovoltaic and the electric quantity of the load can not be supplied by the photovoltaic is achieved;
at the moment, the load supplied by the photovoltaic power system accounts for 41.62% of the total day, and the load power demand accounts for 58.38% of the total day power;
ideally, the self-balancing permeability is 3.44, and the second stage photovoltaic permeability ranges from 1 to 3.44;
third stage
When the photovoltaic permeability is greater than the self-balancing permeability of 3.44, the power demand of the load will not change, and the change trend of the power demand will not change, if the photovoltaic configuration is continuously increased at this time:
in terms of electric quantity, the electric quantity requirement in the first period and the third period is reduced, so that the total electric quantity requirement of the load is reduced, and when the photovoltaic power tends to be infinite under the limit condition, namely the photovoltaic is in the load area, the power supply time period is completely supplied by the photovoltaic, the electric quantity of the photovoltaic supply load is 47.92%, and the electric quantity requirement of the load is 52.08%;
compared with the case that the photovoltaic permeability is equal to 3.44, the electric quantity demand of the load in the limit case is reduced by 6.3%. And the photovoltaic permeability is increased from 1 to 3.44, the electric quantity demand of the load is reduced by 12.41%;
supplementing the first step, if the energy transfer equipment is used for transferring redundant photovoltaic electric quantity, when the photovoltaic permeability is greater than 3.44, the excess electric quantity cannot be supplied to the load, and no additional benefit can be obtained for the energy transfer equipment;
and improving the photovoltaic configuration does not affect the power demand of the load from the power perspective, but the power of the power grid is reversely transmitted, so that the power grid is adversely affected.
The method for evaluating the regulation capacity requirement of the power system containing the high-proportion renewable energy comprises the steps of selecting indexes and analyzing the change condition of the photovoltaic permeability in three stages. Has the advantages of scientific and reasonable method, strong applicability, good effect and the like.
Drawings
FIG. 1 is a schematic view of a photovoltaic permeability variation curve;
FIG. 2 is a graph illustrating a lower limit of power demand;
FIG. 3 is a schematic diagram of load power demand;
FIG. 4 is a schematic view of a force curve;
FIG. 5 is a schematic view of a load demand curve;
FIG. 6 is a diagram illustrating a power demand curve of a load;
FIG. 7 is a schematic diagram illustrating a variation curve of the power demand of the load;
FIG. 8 is a power curve for a photovoltaic and load with a photovoltaic permeability of 3.44;
FIG. 9 is a schematic diagram of power demand and power demand;
FIG. 10 is a graph comparing the rate of change of the upper and lower limits of the turndown capability;
FIG. 11 is a graph comparing the rate of change of the upper and lower limits of the adjustment capability.
Detailed Description
The method for evaluating the regulation capacity requirement of the power system containing high-proportion renewable energy according to the invention is described in detail by using the attached drawings and the embodiment.
Referring to fig. 1 to fig. 11, the method for evaluating the regulation capability requirement of the power system containing high proportion of renewable energy sources of the present invention includes the following steps:
1) selecting indexes: drawing a two-dimensional image according to the selected index to describe the matching condition of the claim load and the photovoltaic under a certain configuration, analyzing the regulation capacity requirement under a certain matching condition,
(1) capacity matching rate Vs: the coincidence degree of the area enclosed by the photovoltaic output curve and the load curve;
Figure BDA0003136667150000051
(2) peak to peak ratio Vp: contract rate of absolute values of distances between the peak time moment of the photovoltaic curve and the peak time moment of the load;
Figure BDA0003136667150000052
wherein the peak time of the photovoltaic curve is tPVAnd the peak time of the load curve is tload，|tPV-tloadI is the peak resultant difference;
(3) rate of change of regulating capacity: defining the reduction of the upper limit of the adjusting capacity as a positive value and the increase of the lower limit of the adjusting capacity as a negative value;
reduction rate of upper limit of regulating power
Figure BDA0003136667150000053
Rate of increase of lower limit of regulating power
Figure BDA0003136667150000054
Rate of change of upper and lower limits of regulating power Vi＝Vcap+Vfloor
Wherein
Figure BDA0003136667150000061
Is the annual average value of the load, PminIs the minimum value of the load, PmaxIs the maximum load value;
2) when the photovoltaic permeability changes, the regulation capacity requirement of the load also changes, and the photovoltaic permeability change condition is divided into three stages to be analyzed
(1) First stage
When the photovoltaic permeability is between 0 and 1, it is obvious that the photovoltaic is in an unsaturated state for the load at this time, and all the photovoltaic can be used for supplying power to the load, and because the photovoltaic output is small at this time, most of the load needs external supply, namely, the part of the capacity regulation requirement, which includes two parts of power requirement and electric quantity requirement, which need to be changed along with the change of the photovoltaic permeability. Fig. 1 is a graph of the change in photovoltaic permeability from 0 to 1.
Defining the generation time of the photovoltaic effective output as t1The end time of the photovoltaic effective output is t4Then define the electric quantity E of the photovoltaic supply loadPVThe calculation formula is as follows:
Figure BDA0003136667150000062
the calculation formula of the load demand electric quantity is as follows:
Eload,need＝Eload-EPV
wherein P isPVTo photovoltaic power, EloadFor the total daily power of the load, Eload，needThe total daily electric quantity of the target load is.
When the photovoltaic permeability is less than 1, it is apparent that the upper power demand limit of the load is constant and 1, while the lower power demand limit of the load is changed in equal proportion. Since the change of the photovoltaic permeability is proportionally changed according to the load power, and the load power demand is calculated by subtracting the photovoltaic power from the load power, the change is also proportionally changed, as shown in fig. 2, the photovoltaic permeability is changed from 0 to 1, and the lower limit value of the power demand is a diagonal straight line changed from 1 to 0.
And the electric quantity demand of the load is changed in proportion to the integral of the area of the load, which is also changed in proportion to the photovoltaic permeability, so that the electric quantity demand of the load is a straight line which is decreased from 24 when the photovoltaic permeability is changed from 0 to 1, as shown in fig. 3.
As can be seen from fig. 3, when the photovoltaic permeability is 1, the power demand of the load is about 17 and 16.99, that is, the load demand at this time is 70.79% of the load all day, and the load supplied by the photovoltaic is 29.21%.
For the analysis of the critical case, when the maximum photovoltaic power reaches the load power of 1, i.e. when the photovoltaic permeability is 1, the output curve is shown in fig. 4.
Obviously, the photovoltaic is completely supplied to the load without any surplus part, and the problem of photovoltaic electric quantity transferring to the power grid is avoided. As shown in fig. 5, the load demand at this time is power demand under ideal conditions, the integral of each part of the load demand is power demand of each time interval, the power demand does not have a zero crossing point, and the power demand is 8.37 and 8.62 at the time when the photovoltaic power reaches the peak value at 11 time, which respectively accounts for 34.88% and 35.92% of the load all day. Namely, the total photovoltaic power requirement at this time is 16.99%, and corresponding to the above conclusion, the total photovoltaic power requirement accounts for 70.79% of the total daily load. And the upper power demand limit is 1 and the lower limit is 0.
(2) Second stage
When the photovoltaic permeability is greater than 1, the upper limit of the power demand of the load still does not become 1, because no matter how the photovoltaic permeability increases, there is a time during which the load cannot be supplied, such as a night time period, and therefore the upper limit power demand of the load does not change. And because the photovoltaic permeability is greater than 1, the situation that the photovoltaic power is greater than the load power can occur, the photovoltaic power is surplus, the redundant part cannot be supplied with the load and can only be sent to the power grid, the zero crossing point of the load power demand also occurs, obviously, the power demand cannot have a negative value, and therefore, the lower limit of the load power is 0. In summary, when the photovoltaic permeability is greater than 1, no matter how much the photovoltaic permeability increases, the upper limit of the power demand of the load is fixed to 1, and the lower limit is fixed to 0.
Therefore, the power demand of the load is mainly analyzed, as shown in fig. 6, when the photovoltaic permeability is increased from 1, although the photovoltaic power is still increased in an equal proportion, since the photovoltaic power is greater than the load power at this time, the increased photovoltaic power cannot sufficiently supply the load, and thus the power demand of the load is no longer increased in an equal proportion.
According to fig. 6, taking the case of the photovoltaic permeability of 2 as an example, four moments are defined, and the moment when the photovoltaic starts to exert force is denoted as t1Respectively recording two moments with equal photovoltaic and load as t according to time sequence2And t3And recording the photovoltaic ending output moment as t4. (in this ideal example, t1The instant is actually 6:25，t4the time is actually 18: 00)
when the photovoltaic permeability is greater than 1, the photovoltaic power supply quantity E at the moment is definedPVComprises the following steps:
Figure BDA0003136667150000071
defining the load demand electric quantity as follows:
Eload,need＝Eload-EPV
wherein P isloadIs the load power.
The power demand variation curve of the load is shown in fig. 7 in combination with the case that the photovoltaic permeability is less than 1.
During the change process which increases after the photovoltaic permeability is greater than 1, there occurs a phenomenon of electrical quantity self-balancing of the photovoltaic and the load when the photovoltaic permeability is equal to 3.44, the photovoltaic permeability is analyzed as follows for the case where it is equal to 3.44:
fig. 8 is a power curve of photovoltaic and load with a photovoltaic permeability of 3.44, from which a load demand curve can be derived. Due to the fact that the photovoltaic permeability is extended, the photovoltaic power is larger than the load power, the photovoltaic electric quantity is sent back to the power grid, and the time is t2And t3Within a time range. Thus dividing the time of day into 0-t2Period of time, t2-t3Time period and t3And 24, the first section and the third section respectively represent that the power demand and the electric quantity demand are greater than zero, namely power and electric quantity need to be obtained from the power grid, and the second section represents that the power demand and the electric quantity demand are less than zero, namely photovoltaic power is surplus and electric quantity can be transmitted to the power grid. At the moment, the electric quantity demand accumulated values of the three time intervals are respectively 6.88, -14.01 and 7.13, the absolute values of the three time intervals respectively account for 28.67%, 58.38% and 29.71% of the total electric quantity of the load in the whole day, namely, the sum of the first section and the third section is equal to the absolute value of the second section, namely, the surplus photovoltaic electric quantity is transferred to the part with insufficient electric quantity in the day through the energy transfer equipment, so that the electric quantity demand in the whole day can be just met, namely, the surplus photovoltaic electric quantity and the load which cannot be supplied by the photovoltaic can be achievedThe amount is self-balancing. See fig. 9.
The load supplied by the photovoltaic now accounts for 41.62% of the total day, and the load power demand accounts for 58.38% of the total power of the day.
It can be seen that in this ideal case, the self-balancing permeability is 3.44 and the photovoltaic permeability of the second stage ranges from 1 to 3.44.
(3) The third stage
And when the photovoltaic permeability is greater than the self-balancing permeability of 3.44, the power demand of the load does not change, and the change trend of the electric quantity demand does not change, if the photovoltaic configuration is continuously increased at the moment:
in terms of electric quantity, the electric quantity requirements of the first period and the third period are reduced, obviously, the total electric quantity requirement of the load is reduced, and in the limit condition, when the photovoltaic power tends to be infinite, namely the photovoltaic power is in the load area, the time period (t) of power supply is available (t)1To t4Time of day) is all powered by the photovoltaic (i.e., the rectangular shaped power delivery area), the photovoltaic supplies the load with 47.92% of power and the load has a power demand of 52.08%.
Compared with the photovoltaic permeability equal to 3.44, the electric quantity demand of the load in the limit case is reduced by 6.3%. And the photovoltaic permeability is increased from 1 to 3.44, the electricity demand of the load is reduced by 12.41%.
And secondly, supplementing the first step, if the energy transfer equipment is used for transferring redundant photovoltaic electric quantity, when the photovoltaic permeability is more than 3.44, the extra electric quantity cannot be supplied to the load, and extra benefits cannot be obtained for the energy transfer equipment.
Improving the photovoltaic configuration does not affect the power demand of the load from the power perspective, but adversely affects the power grid due to the existence of power transferred to the power grid.
From the above three phases, it can be seen that when the photovoltaic permeability increases from 0:
the upper limit of the power demand of the load is constantly and constantly 1 along with the increase of the photovoltaic permeability, the lower limit of the power demand is changed in an equal proportion when the photovoltaic permeability is less than 1, and is constantly and constantly 0 when the photovoltaic permeability is more than 1;
with the increase of the photovoltaic permeability, the electric quantity demand of the load is continuously reduced, the photovoltaic permeability is reduced in equal proportion when being smaller than 1, and the reduction speed is reduced when being larger than 1, and the reduction speed is similar to a logarithmic function form;
thirdly, when the photovoltaic permeability is 1, the load demand electric quantity accounts for 70.79% of the total electric quantity of the whole day;
and fourthly, the special photovoltaic permeability is 3.44, at the moment, the load required electric quantity accounts for 58.38% of the total electric quantity of the whole day, the photovoltaic light abandoning electric quantity is equal to the load required electric quantity, and the load electric quantity can be reduced by continuously increasing the photovoltaic power, but the slowing proportion is too low, and the power of a power grid which is sent backwards is too high, so that the power grid is adversely affected.
The following are example analyses: in the example, load data of a Jilin area is selected, the data length is 1 year (2014), and the sampling interval is 15 min; load maximum 146.73MW, load minimum 60.35 MW. Photovoltaic data is generated by selecting meteorological conditions in Jilin areas through Meteonorm7.3 software. The photovoltaic permeability is respectively 50%, 20% and 70%; the following three points are mainly analyzed: 1) peak-to-peak load vs. photovoltaic conditions; 2) a curve of maximum and minimum values of load data all year round, and a curve of maximum and minimum values after the load is increased by photovoltaic; 3) and adjusting the change rate trend of the upper limit and the lower limit of the capacity. Three different photovoltaic configurations were compared: first, formula definition can find that changing the photovoltaic configuration does not change the peak-to-peak ratio, so the peak-to-peak ratio curves are the same. It is not difficult to see that the capacity matching rate is 99.98% at 70% permeability, and when the photovoltaic permeability is lower than 70%, the capacity matching rate can be considered to be equal to 100%. The upper and lower limit variation rate curves of the three photovoltaic configurations are superimposed to obtain fig. 10 and fig. 11. The following data are available as in table 1.
TABLE 1 data corresponding to different photovoltaic permeabilities
Figure BDA0003136667150000091
From fig. 10a, it can be concluded that: when the photovoltaic permeability changes within a range of ensuring the capacity matching rate to be 100%, the reduction rate of the upper limit of the adjustment capacity initially varies greatly (20% to 50%), but after a certain critical point, the reduction range of the upper limit of the adjustment capacity gradually decreases. In fact, for a unimodal load, as long as the increased photovoltaic system output is large enough, the reduction of the upper limit of the regulation capacity must increase with the increase of the photovoltaic system configuration, but for the load in the jilin area, which is a bimodal load, it can be seen from the peak-to-peak rate data that the lowest peak-to-peak rate level in this area is 0.59, and the average value is 0.87, so that generally, the peak time of the photovoltaic output does not exceed four hours from the peak time of the load, and the value gradually decreases as the year ends approach, which means that the peak time of the photovoltaic output is further away from the second peak time, which results in the continued increase of the photovoltaic configuration on the basis, and the secondary peak cannot be well affected, that is, the further increase of the photovoltaic configuration is caused, but the reduction of the upper limit of the regulation capacity is less obvious. 2) As can be seen from fig. 10b, it is clear that the trend of the lower limit of the turndown capacity is clearly not affected by the above rule, and increasing the photovoltaic configuration necessarily leads to a significant reduction of the lower limit of the turndown capacity. 3) Therefore, according to the two points 1) and 2) and fig. 11, it can be known that, aiming at the load and photovoltaic characteristics in the Jilin area, on the premise of only considering the influence factor of the regulation capacity, it is obvious that excessive photovoltaic configuration is unfavorable for the regulation capacity of the power system, and when the photovoltaic configuration is at a lower level (about 20%), the average value of the upper and lower limit change rates is positive, and the regulation capacity of the power grid is obviously positively influenced; when the photovoltaic configuration is 50%, the average value of the upper and lower limit rates of change is-7.7%, which is approximately zero, and it can be considered that no or little influence is exerted on the grid. When the photovoltaic configuration continues to increase, the lower limit of the regulating capacity which needs to be obtained from the power grid is obviously too large, and can even reach more than 50% of the average value of the load, and the average value even exceeds 20%, which obviously is a great burden on the power grid.
The terms, diagrams, tables and the like in the embodiments of the present invention are used for further description, are not exhaustive, and do not limit the scope of the claims, and those skilled in the art can conceive of other substantially equivalent alternatives without inventive step in light of the teachings of the embodiments of the present invention, which are within the scope of the present invention.

Claims (1)

1. A demand evaluation method for regulating capacity of a power system containing high-proportion renewable energy is characterized by comprising the following steps: it comprises the following contents:
1) selecting indexes: drawing a two-dimensional image according to the selected index to describe the matching condition of the claim load and the photovoltaic under a certain configuration, analyzing the regulation capacity requirement under a certain matching condition,
(1) capacity matching rate Vs: the coincidence degree of the area enclosed by the photovoltaic output curve and the load curve;
Figure FDA0003136667140000011
(2) peak to peak ratio Vp: contract rate of absolute values of distances between the peak time moment of the photovoltaic curve and the peak time moment of the load;
Figure FDA0003136667140000012
wherein the peak time of the photovoltaic curve is tPVAnd the peak time of the load curve is tload，|tPV-tloadI is the peak resultant difference;
(3) rate of change of regulating capacity: defining the reduction of the upper limit of the adjusting capacity as a positive value and the increase of the lower limit of the adjusting capacity as a negative value;
reduction rate of upper limit of regulating power
Figure FDA0003136667140000013
Rate of increase of lower limit of regulating power
Figure FDA0003136667140000014
Rate of change of upper and lower limits of regulating power Vi＝Vcap+Vfloor
Wherein
Figure FDA0003136667140000015
Is the annual average value of the load, PminIs the minimum value of the load, PmaxIs the maximum load value;
2) when the photovoltaic permeability changes, the regulation capacity requirement of the load also changes, and the photovoltaic permeability change condition is divided into three stages to be analyzed
First stage
When the photovoltaic permeability is between 0 and 1, for the load, the photovoltaic is in an unsaturated state, all the photovoltaic can be used for supplying power to the load, the photovoltaic output is insufficient, the load needs to be supplied from the outside, namely, the capacity regulation demand part comprises a power demand part and an electric quantity demand part, and the two parts need to be changed along with the change of the photovoltaic permeability;
defining the photovoltaic effective output generation time t1End time t of effective photovoltaic output4Then the photovoltaic supplies the electrical quantity E of the loadPVThe calculation formula (c) is as follows:
Figure FDA0003136667140000016
and the calculation formula of the load demand electric quantity is as follows:
Eload,need＝Eload-EPV
wherein P isPVTo photovoltaic power, EloadFor the total daily power of the load, Eload，needThe target load total electric quantity of the whole day;
when the photovoltaic permeability is less than 1, obviously, the upper limit of the power demand of the load is constant and 1, and the lower limit of the power demand of the load is changed in equal proportion; the photovoltaic permeability changes proportionally according to the load power, and the load power demand is calculated by subtracting the photovoltaic power from the load power, namely, the photovoltaic power changes proportionally;
the load electric quantity demand is changed in proportion to the integral of the area of the photovoltaic permeability because the photovoltaic permeability is changed in proportion;
analyzing the critical condition, and when the maximum photovoltaic power reaches the load power 1, the photovoltaic permeability is 1;
at the moment, the photovoltaic power is completely supplied to the load without any surplus part, and the problem of transferring the photovoltaic power to the power grid is avoided; for the load demand, the load photovoltaic reduction is the power demand under the ideal condition, the integral of each part of the load demand is the electric quantity demand of each time interval, the power demand has no zero crossing point, the electric quantity demand takes the moment when the photovoltaic power reaches the peak value at the certain moment of 11 as a demarcation point, and the electric quantity demand is 8.37 and 8.62 which respectively account for 34.88 percent and 35.92 percent of the load in the whole day; at the moment, the total photovoltaic power requirement amount in the whole day is 16.99, which corresponds to the conclusion and accounts for 70.79% of the load in the whole day, and the upper limit of the power requirement is 1 and the lower limit is 0;
second stage
When the photovoltaic permeability is greater than 1, the upper limit of the power demand of the load still does not change to 1, because no matter how the photovoltaic permeability is increased, the power demand cannot be supplied to the load for a certain time, and the upper limit power demand of the load is not changed; since the photovoltaic permeability is greater than 1, the photovoltaic power is greater than the load power, the photovoltaic power is surplus, the redundant part cannot be supplied with the load and can only be transferred to the power grid, namely, the zero crossing point of the load power demand occurs, the power demand cannot have a negative value, and the lower limit of the load power is 0; in summary, when the photovoltaic permeability is greater than 1, no matter how the photovoltaic permeability increases, the upper limit of the power demand of the load is fixed to 1, and the lower limit is fixed to 0;
the electric quantity demand of the load is mainly analyzed, after the photovoltaic permeability is increased from 1, although the photovoltaic power is still increased in equal proportion, the photovoltaic power is larger than the load power, the power supply increased by the photovoltaic power cannot be sufficient for supplying the load, and the electric quantity demand of the load is not increased in equal proportion any more;
defining four moments under the condition that the photovoltaic permeability is 2, and recording the photovoltaic initial output moment t1Respectively recording two moments with equal photovoltaic and load according to time sequencet2And t3And recording the photovoltaic ending output moment as t4；
The photovoltaic permeability is defined as the photovoltaic power supply E at the moment when the photovoltaic permeability is greater than 1PVComprises the following steps:
Figure FDA0003136667140000021
defining the load demand capacity is still:
Eload,need＝Eload-EPV
wherein P isloadIs the load power;
analyzing the electric quantity demand change of the load by combining the condition that the photovoltaic permeability is less than 1; in the change process that increases after photovoltaic permeability is greater than 1, appear when photovoltaic permeability equals 3.44, photovoltaic and load electric quantity self-balancing phenomenon, and then the analysis photovoltaic permeability equals the 3.44 condition:
the photovoltaic permeability is 3.44, and the load power is obtained; due to the fact that the photovoltaic permeability is extended, the photovoltaic power is larger than the load power, the photovoltaic electric quantity is sent back to the power grid, and the time is t2And t3Within the time range; dividing the time of day into 0-t2Period of time, t2-t3Time period and t3-24, in a third period, the first and third periods represent that the power demand and the power demand are greater than zero, respectively, i.e. power and power are required to be obtained from the grid, and the second period represents that the power demand and the power demand are less than zero, i.e. photovoltaic power is surplus and power can be transmitted to the grid; at the moment, the electric quantity demand accumulated values in three time intervals are respectively 6.88, -14.01 and 7.13, the absolute values of the three are respectively 28.67%, 58.38% and 29.71% of the total electric quantity of the load in the whole day, namely, the sum of the first section and the third section is equal to the absolute value of the second section, namely, the surplus photovoltaic electric quantity is transferred to the part with insufficient electric quantity in the day through the energy transfer equipment, so that the electric quantity demand in the whole day can be just met, namely, the self-balancing state that the surplus photovoltaic electric quantity and the load cannot be supplied by the photovoltaic is achieved;
at the moment, the load supplied by the photovoltaic power system accounts for 41.62% of the total day, and the load power demand accounts for 58.38% of the total day power;
ideally, the self-balancing permeability is 3.44, and the second stage photovoltaic permeability ranges from 1 to 3.44;
third stage
When the photovoltaic permeability is greater than the self-balancing permeability of 3.44, the power demand of the load does not change, and the change trend of the electric quantity demand does not change, if the photovoltaic configuration is continuously increased:
in terms of electric quantity, electric quantity requirements in a first period and a third period are reduced, total electric quantity requirements of loads are reduced, and when photovoltaic power tends to be infinite under the limit condition, namely the photovoltaic is in a load area, all the power-supply periods are supplied by the photovoltaic, the electric quantity of the loads supplied by the photovoltaic is 47.92%, and the electric quantity requirements of the loads are 52.08%;
compared with the case that the photovoltaic permeability is equal to 3.44, the electric quantity demand of the load in the limit case is reduced by 6.3%. And the photovoltaic permeability is increased from 1 to 3.44, the electric quantity demand of the load is reduced by 12.41%;
supplementing the first step, if the energy transfer equipment is used for transferring redundant photovoltaic electric quantity, when the photovoltaic permeability is greater than 3.44, the excess electric quantity cannot be supplied to the load, and no additional benefit can be obtained for the energy transfer equipment;
improving the photovoltaic configuration does not affect the power demand of the load from the power perspective, but the power of the power grid is reversely transmitted, so that the power grid is adversely affected.
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