CN110571856A - Optimal control method for matching degree of optical storage power station and load time sequence - Google Patents

Abstract

The invention discloses an optimal control method for matching degree of a photovoltaic power storage station and a load time sequence, aiming at effectively improving the photovoltaic consumption level, reducing the investment and operation and maintenance cost of energy storage equipment and improving the utilization rate of the equipment. According to the invention, through controlling the charge and discharge power of the energy storage battery, the time sequence matching degree of the optical storage power station and the load is improved, and the power fluctuation of a line and the disturbance to a power grid are reduced. The method has the advantages of clear flow and clear physical concept, can effectively improve the photovoltaic consumption level, and reduces the investment and operation and maintenance cost of energy storage equipment.

Description

Optimal control method for matching degree of optical storage power station and load time sequence

Technical Field

the invention relates to an optimal control method for matching degree of a photovoltaic power storage station and a load time sequence, and belongs to the technical field of photovoltaic power generation.

Background

Distributed photovoltaic power generation in China is continuously and rapidly developed, and the installed capacity is rapidly increased, so that the distributed photovoltaic power generation becomes one of important power sources in a system. The development of distributed photovoltaic in the middle east region continues to be accelerated, and Jiangsu, Zhejiang, Shandong, Anhui and the like become main regions of the distributed photovoltaic installation.

because photovoltaic power generation has the characteristics of randomness and volatility, the difficulty of power and electric quantity balance of a system is increased by accessing high-capacity photovoltaic power generation into a power grid. According to the statistics of an actual power station, in a period of strong solar irradiation of 10-15 points, cloud layer movement may cause the output power of a photovoltaic power station to fluctuate violently in a short time, and impact is caused on the active power balance of the system. In recent years, the energy storage cost is continuously reduced, electric energy can be transmitted to a power grid to serve as a power supply, and can be absorbed from the power grid to serve as a load, so that the controllability is good, and the development is rapid. The photovoltaic and energy storage combined power station can effectively improve the controllability of the photovoltaic power station and enhance the flexibility of a power grid.

In order to effectively improve the photovoltaic consumption level, reduce the investment and operation and maintenance costs of energy storage equipment and improve the utilization rate of the equipment, a control method of an optical storage power station (including a combined power station of a photovoltaic power station and an energy storage power station, which is referred to as an optical storage power station for short) is urgently needed to be researched.

Disclosure of Invention

The invention aims to provide an optimal control method for the matching degree of the optical storage power station and the load time sequence.

the purpose of the invention is realized by the following technical scheme:

An optimal control method for matching degree of an optical storage power station and a load time sequence comprises the following steps:

step one, collecting historical output data of a photovoltaic power station: selecting historical output data of 365 days in the whole year, and eliminating abnormal data, wherein the value interval dt of the output data is 1-15 minutes;

Step two, collecting historical power load data: selecting historical power load data of 365 days in a whole year in a line, and eliminating abnormal data, wherein the time interval of the power load data is consistent with the time interval of the photovoltaic power generation output data;

Step three, calculating a matching power threshold value P of the output force of the light storage station and the power load_matchThe calculation formula is

Wherein, is Δ V_maxThe upper limit of voltage fluctuation is allowed, and the value range is 0.01-0.03 pu, V_NRated for the line voltage, R_line,PEThe line resistance R between the grid-connected point of the optical storage station and the upper-level transformer_line,LThe load is the line resistance between the upper-level transformers;

Step four, calculating the power deviation P of the photovoltaic output and the power load at each moment_err,tthe calculation formula is as follows:

P_err,t＝P_PV,t-P_L,t (2)

wherein, P_PV,tfor photovoltaic power generation power at time t, P_L,tThe value is the active value of the power load in the line at the moment t;

Step five, according to the power deviation P_err,tAnd the state of charge (SOC) of the energy storage battery, and calculating the charge and discharge power of the energy storage battery;

Stored energy electricityThe charging conditions of the cell were: photovoltaic output greater than electrical load, power deviation P_err,tis of a size e_ess<P_err,t<P_n,ess+P_matchstate of charge SOC of energy storage battery<SOC_maxWherein e is_essthreshold for initiating charging and discharging, P_n,essFor the rated power, SOC, of the energy storage battery_maxis the maximum allowable value; the calculation formula of the charging power of the energy storage battery is as follows:

P_ess,t＝min{max[K_ess(P_err,t-e_ess),P_err,t-P_match],P_n,ess} (3)

wherein K_essthe charge-discharge coefficient is 0 as an initial value and 1 as a maximum value;

The discharge conditions of the energy storage battery are as follows: photovoltaic output less than electrical load, power deviation P_err,tsatisfies-P_n,ess-P_match<P_err,t<-e_essState of charge SOC of energy storage battery>SOC_minWherein SOC is_minIs the minimum allowable value; the discharge power of the energy storage battery is calculated by the following formula:

P_ess,t＝max{min[K_ess(P_err,t+e_ess),P_err,t+P_match],-P_n,ess} (4)

When the charging and discharging conditions of the energy storage battery are not met, the output power of the energy storage battery is 0;

sixthly, calculating the output of the optical storage power station at each moment, wherein the calculation formula is as follows:

P_PE,t＝P_PV,t+P_ess,t (5)

Step seven, calculating the matching power generation power and the matching power consumption power of the output of the photovoltaic power storage station and the power load at each moment, wherein the calculation formula is as follows:

Wherein, P_matchPE,tthe generated power, P, is the matching of the output of the light storage station and the power load at the moment t_matchL,tMatching power consumption of the power output of the light storage station and the power load at the moment t;

Step eight, unmatched data are removed from the output of the optical storage station and the power load to obtain two groups of new array sequences, and a Pearson correlation coefficient between the two groups of sequences is calculated, wherein the calculation formula is as follows:

Wherein, P_matchPE,iFor the ith matched power generation value,To match the mean value of the generated power, P_matchL,iFor the ith matching power consumption value,The average value of the matching power is n, and n is the total number of the array sequences;

step nine, calculating annual matching power generation quantity and matching power consumption quantity of the output of the optical storage station and the power load, wherein the calculation formula is as follows:

E_matchPE＝∑P_matchPE,tdt (9)

E_matchL＝∑P_matchL,tdt (10)

Wherein E is_matchPVFor matching the output of the optical storage station with the annual power generation capacity of the electrical load, E_matchLmatching the power consumption quantity of the photovoltaic power storage station output and the power load all year round;

Step ten, calculating the time sequence matching degree K of the output force of the light storage station and the power load_matchThe calculation formula is as follows:

Wherein E_PEFor the annual generation of electricity in optical storage plants, E_Lthe annual power consumption of the power load;

Eleven, using delta K_essStep length of (1) gradually increasing charge-discharge coefficient K_essand repeating the fifth step to the tenth step, and taking the charge-discharge coefficient with the maximum time sequence matching degree as an optimal value.

The object of the invention can be further achieved by the following technical measures:

The matching degree optimization control method of the optical storage power station and the load time sequence is characterized in that the step length delta K_essIs 0.1.

compared with the prior art, the invention has the beneficial effects that: by controlling the charging and discharging power of the energy storage battery, the time sequence matching degree of the optical storage power station and the load is improved, and the power fluctuation of a line and the disturbance to a power grid are reduced. The method has the advantages of clear flow and clear physical concept, can effectively improve the photovoltaic consumption level, reduces the investment and operation and maintenance cost of energy storage equipment, and improves the utilization rate of the equipment.

Drawings

FIG. 1 is a flow chart of an embodiment of a method for energy storage optimization control;

FIG. 2 is a 365-day-all-year historical generated output curve of a photovoltaic power plant in an embodiment;

FIG. 3 is a historical curve of 365-day-all-year power load in the embodiment;

FIG. 4 is a diagram illustrating the relationship between the charge/discharge coefficient and the timing matching degree in the embodiment;

Fig. 5 is a charging/discharging power curve of the energy storage battery in the embodiment.

Detailed Description

the invention is further described with reference to the following figures and specific examples.

as shown in fig. 1, the method for optimally controlling the matching degree between the optical storage station and the load time sequence includes the following steps:

Step one, collecting historical output data of a photovoltaic power station. Selecting historical output data of 365 days in the whole year, and eliminating abnormal data, wherein the time interval dt of the generated output data is 5 minutes. Fig. 2 shows the historical generated output curve of a photovoltaic power plant for 365 days of the year.

And step two, collecting historical power load data. And selecting historical power loads of 365 days in the whole year in the line, and rejecting abnormal data. The time interval of the power load data and the time interval of the photovoltaic power generation data must be kept in agreement with 5 minutes. Fig. 3 shows the 365-day-all-year history of the electrical load.

Step three, calculating the matching power threshold value of the output force of the optical storage station and the power load, wherein the calculation formula is

Wherein, is Δ V_maxthe upper limit of the voltage fluctuation is expressed by a per unit value, and the value is 0.02pu, V_Nrated voltage of the line is 10kV, R_line,PEThe line resistance of the grid-connected point of the optical storage station is 2.35 omega, R away from the upper transformer_lineFor a load with a line resistance of 1.68 omega from the upper transformer, a matching power threshold of 0.99MW can be obtained. For convenience of calculation, the threshold value is taken to be 1 MW.

Step four, calculating the power deviation P of the photovoltaic output and the power load at each moment_err,tThe calculation formula is as follows:

P_err,t＝P_PV,t-P_L,t (2)

wherein, P_PV,tis the generated power of the photovoltaic at time t, P_L,tThe value of the in-line power load at time t is the active value.

step five, according to the power deviation P_err,tAnd the charge state SOC of the energy storage battery, and calculating the charge and discharge power of the energy storage battery.

The charging conditions of the energy storage battery are as follows: photovoltaic output greater than electrical load, power deviation P_err,tIs of a size e_ess<P_err,t<P_n,ess+P_matchState of charge SOC of energy storage battery<SOC_maxwherein e is_essthreshold of 0.2MW, P for initiating charging and discharging_n,essRated power of 1MW, SOC for energy storage battery_maxIs the maximum allowable value. The calculation formula of the charging power is as follows:

P_ess,t＝min{max[K_ess(P_err,t-e_ess),P_err,t-P_match],P_n,ess} (3)

Wherein K_essThe default initial value is 0 and the maximum value is 1 for the charge-discharge coefficient.

The discharge conditions of the energy storage battery are as follows: photovoltaic output less than electrical load, power deviation P_err,tsatisfies-P_n,ess-P_match<P_err,t<-e_essState of charge SOC of energy storage battery>SOC_minwherein SOC is_minIs the minimum allowed value. The formula for calculating the discharge power is as follows:

P_ess,t＝max{min[K_ess(P_err,t+e_ess),P_err,t+P_match],-P_n,ess} (4)

And when the charging and discharging conditions of the energy storage battery are not met, the output power of the energy storage battery is 0.

sixthly, calculating the output of the optical storage power station at each moment, wherein the calculation formula is as follows:

P_PE,t＝P_PV,t+P_ess,t (5)

Step seven, calculating the matching power generation power and the matching power consumption power of the output of the photovoltaic power storage station and the power load at each moment, wherein the calculation formula is as follows:

wherein, P_matchPE,tthe generated power, P, is the matching of the output of the light storage station and the power load at the moment t_matchL,tand the matching power of the output force of the photovoltaic power storage station and the power load at the time t.

when the absolute value of the deviation between the output of the optical storage station and the power load is less than or equal to 1MW, the output of the optical storage station is considered to be matched with the power load, the matched power generation power is equal to the output of the optical storage station, and the matched power utilization power is equal to the power of the power load; when the absolute value of the deviation between the light storage station output force and the power load is larger than 1MW, the light storage station output force is not matched with the power load, and the matching power generation power and the matching power consumption power are both equal to 0.

step eight, unmatched data are removed from the output of the optical storage station and the power load to obtain two groups of new array sequences, and a Pearson correlation coefficient between the two groups of sequences is calculated, wherein the calculation formula is as follows:

Wherein, P_matchPE,iFor the ith matched power generation value,To match the mean value of the generated power, P_matchL,iFor the ith matching power consumption value,to match the average of the power usage, n is the total number of array sequences.

Step nine, calculating annual matching power generation quantity and matching power consumption quantity of the output of the optical storage station and the power load, wherein the calculation formula is as follows:

E_matchPE＝∑P_matchPE,tdt (9)

E_matchL＝∑P_matchL,tdt (10)

Wherein E is_matchPVFor matching the output of the optical storage station with the annual power generation capacity of the electrical load, E_matchLThe power consumption quantity is matched with the annual power consumption quantity of the power load for the photovoltaic power storage station.

Step ten, calculating the time sequence matching degree of the output force of the optical storage station and the power load, wherein the calculation formula is as follows:

step elevenby Δ K_essStep size of 0.1 increases the charge-discharge coefficient K gradually_essLet K be_essSequentially taking values of 0, 0.1, 0.2, 0.3, …, 0.9 and 1, and repeating the fifth step to the tenth step until K is reached_ess>And 1, stopping circulation, and taking the charge-discharge coefficient with the maximum time sequence matching degree as an optimal value in the calculation result.

FIG. 4 shows the charge-discharge coefficient K_essThe relation between the light storage station output force and the time sequence matching degree of the power load can be seen, and the time sequence matching degree of the light storage station output force and the power load can be seen when K is_essWhen the value is 0.3, the time sequence matching degree of the optical storage power station and the load reaches the maximum value. Fig. 5 shows the charging and discharging power curve of the energy storage battery.

In addition to the above embodiments, the present invention may have other embodiments, and any technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of the claims of the present invention.

Claims (2)

1. the optimal control method for the matching degree of the optical storage power station and the load time sequence is characterized by comprising the following steps of:

Step one, collecting historical output data of a photovoltaic power station: selecting historical output data of 365 days in the whole year, and eliminating abnormal data, wherein the value interval dt of the output data is 1-15 minutes;

Step two, collecting historical power load data: selecting historical power load data of 365 days in a whole year in a line, and eliminating abnormal data, wherein the time interval of the power load data is consistent with the time interval of the photovoltaic power generation output data;

step three, calculating a matching power threshold value P of the output force of the light storage station and the power load_matchthe calculation formula is

wherein, is Δ V_maxThe upper limit of voltage fluctuation is allowed, and the value range is 0.01-0.03 pu, V_NRated for the line voltage, R_line,PEFor the line between the grid-connected point of the optical storage station and the superior transformerResistance, R_line,Lthe load is the line resistance between the upper-level transformers;

Step four, calculating the power deviation P of the photovoltaic output and the power load at each moment_err,tThe calculation formula is as follows:

P_err,t＝P_PV,t-P_L,t (2)

Wherein, P_PV,tFor photovoltaic power generation power at time t, P_L,tthe value is the active value of the power load in the line at the moment t;

Step five, according to the power deviation P_err,tand the state of charge (SOC) of the energy storage battery, and calculating the charge and discharge power of the energy storage battery;

the charging conditions of the energy storage battery are as follows: photovoltaic output greater than electrical load, power deviation P_err,tIs of a size e_ess<P_err,t<P_n,ess+P_matchstate of charge SOC of energy storage battery<SOC_maxWherein e is_essThreshold for initiating charging and discharging, P_n,essfor the rated power, SOC, of the energy storage battery_maxIs the maximum allowable value; the calculation formula of the charging power of the energy storage battery is as follows:

P_ess,t＝min{max[K_ess(P_err,t-e_ess),P_err,t-P_match],P_n,ess} (3)

Wherein K_essThe charge-discharge coefficient is 0 as an initial value and 1 as a maximum value;

the discharge conditions of the energy storage battery are as follows: photovoltaic output less than electrical load, power deviation P_err,tsatisfies-P_n,ess-P_match<P_err,t<-e_essstate of charge SOC of energy storage battery>SOC_minWherein SOC is_minIs the minimum allowable value; the discharge power of the energy storage battery is calculated by the following formula:

P_ess,t＝max{min[K_ess(P_err,t+e_ess),P_err,t+P_match],-P_n,ess} (4)

When the charging and discharging conditions of the energy storage battery are not met, the output power of the energy storage battery is 0;

Sixthly, calculating the output of the optical storage power station at each moment, wherein the calculation formula is as follows:

P_PE,t＝P_PV,t+P_ess,t (5)

step seven, calculating the matching power generation power and the matching power consumption power of the output of the photovoltaic power storage station and the power load at each moment, wherein the calculation formula is as follows:

Wherein, P_matchPE,tThe generated power, P, is the matching of the output of the light storage station and the power load at the moment t_matchL,tMatching power consumption of the power output of the light storage station and the power load at the moment t;

Step eight, unmatched data are removed from the output of the optical storage station and the power load to obtain two groups of new array sequences, and a Pearson correlation coefficient between the two groups of sequences is calculated, wherein the calculation formula is as follows:

Wherein, P_matchPE,iFor the ith matched power generation value,To match the mean value of the generated power, P_matchL,iFor the ith matching power consumption value,The average value of the matching power is n, and n is the total number of the array sequences;

Step nine, calculating annual matching power generation quantity and matching power consumption quantity of the output of the optical storage station and the power load, wherein the calculation formula is as follows:

E_matchPE＝∑P_matchPE,tdt (9)

E_matchL＝∑P_matchL,tdt (10)

Wherein E is_matchPVFor matching the output of the optical storage station with the annual power generation capacity of the electrical load, E_matchLMatching the power consumption quantity of the photovoltaic power storage station output and the power load all year round;

Step ten, calculating the time sequence matching degree K of the output force of the light storage station and the power load_matchThe calculation formula is as follows:

wherein E_PEfor the annual generation of electricity in optical storage plants, E_LThe annual power consumption of the power load;

Eleven, using delta K_essStep length of (1) gradually increasing charge-discharge coefficient K_essAnd repeating the fifth step to the tenth step, and taking the charge-discharge coefficient with the maximum time sequence matching degree as an optimal value.

2. the method of claim 1 wherein the step length Δ K is a function of the optimal matching between the optical storage plant and the load timing sequence_essis 0.1.