CN-116207781-B - Two-stage photovoltaic power fluctuation smoothing method based on wavelet packet decomposition technology

CN116207781BCN 116207781 BCN116207781 BCN 116207781BCN-116207781-B

Abstract

The invention relates to the technical field of grid-connected photovoltaic power generation system operation, in particular to a two-stage photovoltaic power fluctuation smoothing method based on wavelet packet decomposition technology. And obtaining the HESS implementation adjustment command through a two-stage photovoltaic power fluctuation smoothing method. And decomposing the photovoltaic output power signal by using a wavelet packet method, and calculating the stabilized target power and the stored energy charging and discharging power by combining the amplitude-frequency information of the photovoltaic power signal and the performance characteristics of different types of stored energy, so as to realize the smoothing effect of the photovoltaic grid-connected power.

Inventors

WENG LIGUO
CHEN SICHAO
LIAN DEQIANG
LUO MAN
SHOU TING
LUO HAIFENG

Assignees

浙江中新电力工程建设有限公司
国网浙江杭州市萧山区供电有限公司

Dates

Publication Date: 20260508
Application Date: 20230112

Claims (3)

1. The two-stage photovoltaic power fluctuation smoothing method based on the wavelet packet decomposition technology is characterized by comprising the following steps of: S1, establishing a grid-connected photovoltaic-hybrid energy storage system, wherein the photovoltaic-hybrid energy storage system comprises a photovoltaic system PV, a hybrid energy storage system HESS and a local controller, and the hybrid energy storage system comprises a battery and a super capacitor; s2, acquiring a photovoltaic system power generation real-time power signal and short-term photovoltaic power output prediction data of 1 minute by using a local controller according to the grid-connected photovoltaic-hybrid energy storage system in the S1; s3, according to the national grid photovoltaic grid-connected standard suggestion, two photovoltaic active power fluctuation standards with different time scales are formed, wherein the photovoltaic active power fluctuation standards are respectively 1 minute and 10 minutes; S4, according to the related data in the S2, a two-stage photovoltaic power fluctuation smoothing method is adopted, wherein the two stages of the two-stage photovoltaic power fluctuation smoothing method comprise a filtering stage and an adjusting stage, the filtering stage adopts a wavelet packet decomposition technology to process future short-term photovoltaic power generation capacity prediction data, and the adjusting stage adopts a local controller to generate a command for adjusting HESS in real time according to photovoltaic active power fluctuation standards of different time scales, so that the fluctuation effect of smooth photovoltaic power generation power is obtained; Said step S4 comprises the sub-steps of: S4-1, selecting 1 minute as marginal charge/discharge response time between the battery and the supercapacitor according to the difference of response time between the balance battery and the supercapacitor; S4-2, filtering signals by adopting a six-layer wavelet packet decomposition strategy according to short-term prediction of photovoltaic power in the S2, and obtaining a first-stage power command of a battery and a supercapacitor; S4-3, judging whether the filtered grid-connected power meets the fluctuation standard or not by adopting the 1-minute photovoltaic active power fluctuation standard in S3, and adjusting the photovoltaic grid-connected power by adjusting the charge and discharge command of the super capacitor if the filtered grid-connected power does not meet the fluctuation standard, and if the filtered grid-connected power does not meet the fluctuation standard, turning to S4-4; s4-4, according to the filtered grid-connected power in S4-2, taking 1 minute as a time interval for adjusting the HESS command, judging whether the filtered grid-connected power meets the fluctuation standard by adopting the 10 minute photovoltaic active power fluctuation standard in S3, if not, adjusting the charge and discharge command of the battery, and adjusting the photovoltaic grid-connected power, and if so, directly turning to the step S4-5; S4-5, if the sampling duration is not reached, the algorithm continues, directly jumps to S4-2, adjusts the HESS command at the next moment, and if the sampling duration is reached, terminates the algorithm.
2. The method for smoothing two-stage photovoltaic power fluctuations based on wavelet packet decomposition technique according to claim 1, wherein: the grid-connected photovoltaic-hybrid energy storage system described in steps S1 and S2 satisfies the following power balance: Wherein, the Is grid-connected photovoltaic power after HESS smoothing; Is the original photovoltaic power; And For both variables, positive values represent discharge, negative values represent charge; The photovoltaic active power fluctuation standards of two different time scales are as follows: The national grid photovoltaic grid-connected standard suggests that for a photovoltaic power generation system with 50MW installed capacity, the photovoltaic active power fluctuation must not exceed 10% of the installed capacity within 1 minute and must not exceed 30% within 10 minutes; The photovoltaic power fluctuation rate within 1 minute is The maximum and minimum values of the photovoltaic power fluctuation limit within 1 minute are respectively And : Wherein, the And The maximum value and the minimum value of grid-connected photovoltaic power in a period of time; Is the installed capacity of the photovoltaic system; The photovoltaic power fluctuation rate within 10 minutes is Maximum and minimum photovoltaic power fluctuation limit within 10 minutes are And ; 。
3. The method for smoothing two-stage photovoltaic power fluctuations based on wavelet packet decomposition technique according to claim 1, wherein: said step S4-2 comprises the sub-steps of: S4-2-1, six-layer wavelet packet decomposition of high frequency component of short-term predictive data of photovoltaic power A different set of signals, the frequency bandwidth of each signal can be given as : Wherein the method comprises the steps of Is the number of layers; Is the sampling frequency; S4-2-2, the frequency bandwidth of the signal of the six-layer wavelet packet decomposition is 0.0078Hz according to the rule in S4-2-1, the marginal response time of the response frequency corresponding to 1 minute is 0.0167 Hz, and the signal corresponding to the response frequency of 1 minute is derived from the signal of the 6-layer wavelet packet decomposition - Is a low frequency part; low frequency part obtained by filtering For grid-connected power, high-frequency signals - The remaining high frequency portion is suppressed by the super capacitor; s4-2-3, combining power by filtering, the first stage commands of HESS can be divided into first stage battery power commands And first stage supercapacitor power : Wherein, the Grid-connected power filtered using wavelet packet decomposition, Is the original photovoltaic power.

Description

Two-stage photovoltaic power fluctuation smoothing method based on wavelet packet decomposition technology Technical Field The invention relates to the technical field of grid-connected photovoltaic power generation system operation, in particular to a two-stage photovoltaic power fluctuation smoothing method based on wavelet packet decomposition technology. Background In recent years, photovoltaic power generation has received increasing attention and development as an environmentally friendly renewable energy source. The permeability of photovoltaic power generation systems in the power grid has been rapidly increasing. However, grid-tied photovoltaic power generation system operation presents a number of technical challenges. In general, photovoltaic power generation is affected by irradiance changes or other environmental factors. Due to the strong fluctuation and intermittence of photovoltaic power generation, the photovoltaic power generation has great influence on the power quality and reliability of a power grid. Furthermore, the national grid has issued technical requirements for photovoltaic power plants, under different constraints, the maximum power fluctuations for different periods of time should be alleviated. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a two-stage photovoltaic power fluctuation smoothing method based on a wavelet packet decomposition technology, which is used for obtaining HESS implementation adjustment commands through the two-stage photovoltaic power fluctuation smoothing method. In order to achieve the above purpose, the invention is realized by the following technical scheme: a two-stage photovoltaic power fluctuation smoothing method based on wavelet packet decomposition technology comprises the following steps: S1, establishing a grid-connected photovoltaic-hybrid energy storage system, wherein the photovoltaic-hybrid energy storage system comprises a photovoltaic system (PV), a Hybrid Energy Storage System (HESS) and a local controller, and the hybrid energy storage system comprises a battery and a super capacitor; s2, acquiring a photovoltaic system power generation real-time power signal and short-term photovoltaic power output prediction data of 1 minute by using a local controller according to the grid-connected photovoltaic-hybrid energy storage system in the S1; s3, according to the national grid photovoltaic grid-connected standard suggestion, two photovoltaic active power fluctuation standards with different time scales are formed, wherein the photovoltaic active power fluctuation standards are respectively 1 minute and 10 minutes; S4, according to the related data in the S2, a two-stage photovoltaic power fluctuation smoothing method is adopted, the two stages of the two-stage photovoltaic power fluctuation smoothing method comprise a filtering stage and an adjusting stage, the filtering stage adopts a wavelet packet decomposition technology to process future short-term photovoltaic power generation capacity prediction data, and the adjusting stage adopts a local controller to generate commands for adjusting HESS in real time according to photovoltaic active power fluctuation standards of different time scales, so that the fluctuation effect of smooth photovoltaic power generation power is obtained. Preferably, the grid-connected photovoltaic-hybrid energy storage system described in steps S1 and S2 satisfies the following power balance: Pg(t)＝Po(t)+Pbat(t)+Psc(t) Wherein P g (t) is grid-connected photovoltaic power after HESS smoothing, P o (t) is original photovoltaic power, P bat (t) and P sc (t) are power of a battery and a super capacitor respectively, and for the two variables, positive values represent discharge and negative values represent charge; The photovoltaic active power fluctuation standards of two different time scales are as follows: The national grid photovoltaic grid-connected standard suggests that for a photovoltaic power generation system with 50MW installed capacity, the photovoltaic active power fluctuation must not exceed 10% of the installed capacity within 1 minute and must not exceed 30% within 10 minutes; the photovoltaic power fluctuation rate within 1 minute is R 1 (t), and the maximum and minimum values of the photovoltaic power fluctuation limit within 1 minute are P 1,max (t) and P 1,min (t), respectively: Wherein max { P g (t- Δt) } and min { P g (t- Δt) } are the maximum value and the minimum value of grid-connected photovoltaic power in a period of time, and P r is the installed capacity of the photovoltaic system; The photovoltaic power fluctuation rate within 10 minutes is R 10 (t), and the maximum and minimum values of the photovoltaic power fluctuation limit within 10 minutes are P 10,max (t) and P 10,min (t); preferably, the step S4 includes the following substeps: S4-1, selecting 1 minute as marginal charge/discharge response time between the battery and the supercapacitor