CN111435789B - Photovoltaic stabilization method and system based on novel wavelet packet basis decomposition - Google Patents
Photovoltaic stabilization method and system based on novel wavelet packet basis decomposition Download PDFInfo
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Abstract
The invention discloses a photovoltaic stabilizing method based on a novel wavelet packet basis decomposition algorithm, which comprises the following steps: s1: acquiring short-time photovoltaic prediction data and generating photovoltaic fluctuation rate; s2: calculating the photovoltaic fluctuation rate through a novel wavelet packet basis decomposition algorithm to generate a first target power; s3: a scheduling signal is generated by a first target power. According to the invention, by improving the traditional wavelet packet basis decomposition algorithm and introducing the evaluation function, the operation speed and the operation efficiency of the algorithm can be improved through the additivity of the evaluation function, and different first power tracks can be formed based on the photovoltaic fluctuation ratios of different time periods, so that the highest approach degree of the scheduling signal and the first power tracks can be ensured at any time, and the photovoltaic stabilizing system can be enabled to adaptively distribute the integral output of the photovoltaic power generation unit and the photovoltaic stabilizing unit and improve the operation speed of the photovoltaic power generation unit and obtain better real-time performance and stabilizing effect.
Description
Technical Field
The invention relates to the technical field of photovoltaic fluctuation stabilization of power distribution networks, in particular to a photovoltaic stabilization method and system based on novel wavelet packet basis decomposition.
Background
With the increasing decrease of traditional energy sources and the increasing prominence of environmental problems, the strong development and utilization of renewable energy sources have become the basic national policy of China. The photovoltaic power generation is one of ideal sustainable energy sources, and has the characteristics of no pollution, no noise, safety, reliability and the like.
However, as the installed capacity of the photovoltaic power in the power grid gradually increases, random fluctuation of the photovoltaic power generation power can influence real-time power balance of the power grid, so that voltage and frequency fluctuation of the power grid is caused, and the power quality and stability of the power grid are influenced. And grid scheduling becomes difficult because these fluctuations are difficult to predict. The photovoltaic fluctuation stabilizing method for limiting the photovoltaic power fluctuation within a certain range is a key technology for large-scale application of photovoltaic power generation, reducing waste light and solving the current energy crisis.
The full-power converter (FSC) variable-speed pumped storage system is flexible and reliable in operation, rapid in working condition conversion and small in environmental pressure, is a most mature, economical and maximum-capacity energy storage mode currently acknowledged, utilizes hydraulic resources to stabilize photovoltaic power fluctuation, is a hot spot of current research, and has a large development space. However, compared with the photovoltaic fluctuation speed, the problem that the pumped storage dynamic power adjustment capability is slow still exists, and on the basis of considering the pumped storage dynamic response capability, how to reasonably distribute the output of the pump storage dynamic power adjustment capability to achieve a better stabilizing effect is a key point of the technology.
At present, a scholars apply wavelet packet decomposition to stabilize photovoltaic fluctuation by using an FSC variable-speed pumped storage system, the wavelet packet decomposition divides the photovoltaic fluctuation in a multi-level manner, and the output of the scholars is reasonably distributed according to the characteristic of photovoltaic fluctuation and the characteristic of energy storage on the basis of fully analyzing the amplitude-frequency characteristic of photovoltaic power, so that a better stabilizing effect is obtained. However, photovoltaic stabilization has real-time performance, and the traditional wavelet packet decomposition algorithm takes longer time, is fixed in layers and has no adaptability.
In summary, there are still problems in the photovoltaic power generation field that when the photovoltaic stabilizing device is used for stabilizing photovoltaic power fluctuation, the following performance of the photovoltaic power fluctuation is poor and the stabilizing effect is poor.
Disclosure of Invention
In view of the above, the invention provides a photovoltaic stabilizing method based on a novel wavelet packet-based decomposition algorithm, which solves the problems of longer processing time and no self-adaptability of the traditional photovoltaic stabilizing method by improving the processing method of the photovoltaic fluctuation rate.
In order to solve the technical problems, the technical scheme of the invention is to adopt a photovoltaic stabilizing method based on a novel wavelet packet basis decomposition algorithm, which is characterized by comprising the following steps: s1: acquiring short-time photovoltaic prediction data and generating photovoltaic fluctuation rate; s2: calculating the photovoltaic fluctuation rate through a novel wavelet packet basis decomposition algorithm to generate a first target power; s3: a scheduling signal is generated by a first target power.
Optionally, the S2 includes: s21: generating a photovoltaic power signal based on the photovoltaic fluctuation rate; s22: executing the novel wavelet packet-based decomposition algorithm on the photovoltaic power signal to generate a multi-layer wavelet packet signal; s23: and acquiring a node with the minimum evaluation function value in the multi-layer wavelet packet base and marking the node as the first target power.
Optionally, the S23 includes: s231: acquiring a first power track sequence; s232: acquiring an evaluation function for evaluating the approach degree of the wavelet packet signal and the first power track sequence; s233: starting from the decomposition of the first-layer wavelet packet, calculating the evaluation function value of the parent node and the evaluation function value of the child node until the node with the minimum evaluation function value is obtained.
Optionally, the S231 includes: s2311: collecting the photovoltaic power signals of a plurality of prediction periods to generate a sampling sequence; s2312: acquiring a first power track function formed by the sampling sequences of adjacent prediction periods; s2313: accumulating and summing a plurality of the first power track functions in a plurality of prediction periods to generate a second power track function; s2314: and generating the first power track sequence by performing discrete point taking on the second power track function.
Optionally, the S3 includes: s31: acquiring a second target power and generating a second power track sequence; s32: calculating the second target power through a novel wavelet packet basis decomposition algorithm and generating an optimal wavelet packet signal; s33: a first output power is generated based on the optimal wavelet packet signal and the second power trace sequence.
Optionally, the step S3 further includes: s34: generating a second output power based on the optimal wavelet packet signal, the photovoltaic power signal, and the first target power; s35: the scheduling signal is generated based on the first output power and the second output power.
Optionally, the photovoltaic stabilization method further includes determining whether the photovoltaic fluctuation rate is higher than a grid-connected standard, where the photovoltaic power generation unit performs grid connection when the photovoltaic fluctuation rate does not exceed the grid-connected standard; and under the condition that the photovoltaic fluctuation rate exceeds the grid-connected standard, the control center calculates the photovoltaic fluctuation rate through a novel wavelet packet base decomposition algorithm to generate a scheduling signal.
Correspondingly, the invention provides a photovoltaic stabilizing system based on a novel wavelet packet base decomposition algorithm, which comprises the following components: the photovoltaic power generation unit is used for acquiring the short-time photovoltaic prediction data and generating a photovoltaic fluctuation rate; the control center calculates the photovoltaic fluctuation rate to generate a first target power through a novel wavelet packet basis decomposition algorithm, and generates a scheduling signal through the first target power; and the photovoltaic stabilizing unit is used for receiving the scheduling signal and restraining photovoltaic power fluctuation.
Optionally, the photovoltaic stabilization unit comprises: a first photovoltaic stabilizing unit: a first output power for receiving the scheduling signal capable of suppressing the photovoltaic power fluctuation over a wide range; a second photovoltaic stabilizing unit: the second output power for receiving the scheduling signal enables rapid suppression of the photovoltaic power fluctuation in a smaller range.
Optionally, the control center includes: a first processing unit: for receiving the photovoltaic fluctuation rate and transmitting the scheduling signal to the photovoltaic stabilization unit; a second processing unit: the method comprises the steps of performing the novel wavelet packet decomposition operation and generating the scheduling signal; memory sharing unit: the photovoltaic control system is used for storing historical data such as the photovoltaic fluctuation rate and the scheduling signal and establishing communication connection between the first processing unit and the second processing unit.
The primary improvement of the invention is that the photovoltaic stabilizing method based on the novel wavelet packet base decomposition algorithm is provided, the operation speed and the operation efficiency of the algorithm can be improved through the additivity of the evaluation function by improving the traditional wavelet packet base decomposition algorithm and introducing the evaluation function, and different first power tracks can be formed based on the photovoltaic fluctuation rate of different time periods, so that the highest approach degree of a scheduling signal and the first power tracks can be ensured at all times, the photovoltaic stabilizing system can adaptively distribute the integral output of a photovoltaic power generation unit and a photovoltaic stabilizing unit and improve the operation speed of the photovoltaic power generation unit, and good instantaneity and stabilizing effect are achieved.
Drawings
FIG. 1 is a simplified flow chart of a photovoltaic stabilization method based on the novel wavelet packet-based decomposition algorithm of the present invention;
FIG. 2 is a simplified flow chart of the present invention for generating a first target power;
FIG. 3 is a simplified flow chart of the present invention for obtaining a node with a minimum evaluation function value;
FIG. 4 is a simplified flow chart of the present invention for acquiring a first power trace sequence;
FIG. 5 is a simplified flow chart of the present invention for generating a scheduling signal;
FIG. 6 is a simplified module connection diagram of the photovoltaic stabilization system of the present invention;
FIG. 7 is a simplified flow chart of a preferred embodiment of the control center of the present invention;
FIG. 8 is a circuit diagram of a preferred embodiment of the control center of the present invention;
FIG. 9 is a schematic diagram of a wavelet packet basis decomposition algorithm of the present invention;
FIG. 10 is a simplified module connection diagram of a preferred embodiment of the photovoltaic stabilization system of the present invention; and
fig. 11 is a graph of simulated data of the photovoltaic stabilizing effect of the present invention.
List of reference numerals
1: the control center 2: photovoltaic power generation unit 3: first photovoltaic stabilization unit
4: a second photovoltaic stabilizing unit 5: the first processing unit 6: a second processing unit
7: memory sharing unit
Detailed Description
In order to make the technical solution of the present invention better understood by those skilled in the art, the present invention will be further described in detail with reference to the accompanying drawings and specific embodiments.
As shown in fig. 1, a photovoltaic stabilization method based on a novel wavelet packet-based decomposition algorithm includes:
s1: acquiring short-time photovoltaic prediction data and generating photovoltaic fluctuation rate; preferably, the photovoltaic power generation unit (2) is grid-connected in case the photovoltaic fluctuation ratio does not exceed a grid-connection standard. And if the photovoltaic fluctuation rate exceeds the grid-connected standard, continuing to execute S2. Preferably, the short-time photovoltaic prediction data can be obtained by calculating weather prediction data of each prediction point in the prediction period. Preferably, the photovoltaic fluctuation ratio is defined as the fluctuation output power of the photovoltaic signal per unit time.
S2: calculating the photovoltaic fluctuation rate through a novel wavelet packet basis decomposition algorithm to generate a first target power; preferably, the first target power is defined as the target output power of the photovoltaic power generation unit 2 after the light Fu Gonglv is stabilized and is denoted as P PVObj (t)。
S3: by a first target power P PVObj (t) generating a scheduling signal. Preferably, the scheduling signal is defined as a scheduling instruction for controlling the plurality of photovoltaic stabilizing units, for controlling the output power of the plurality of photovoltaic stabilizing units.
According to the invention, by improving the traditional wavelet packet basis decomposition algorithm and introducing the evaluation function, the operation speed and the operation efficiency of the algorithm can be improved through the additivity of the evaluation function, and different first power tracks can be formed based on the photovoltaic fluctuation ratios of different time periods, so that the highest approach degree of the scheduling signal and the first power tracks can be ensured at any time, and the photovoltaic stabilizing system can reasonably distribute the integral output of the photovoltaic power generation unit and the photovoltaic stabilizing unit and improve the operation speed of the photovoltaic power generation unit and the photovoltaic stabilizing unit, thereby obtaining better real-time performance and stabilizing effect.
To facilitate understanding how the first target power P is generated PVObj (t) further refining the S2, as shown in fig. 2, comprising:
s21: generating a photovoltaic power signal f (t) based on the photovoltaic fluctuation rate;
s22: performing the novel wavelet packet base decomposition algorithm on the photovoltaic power signal f (t) to generate a multi-layer wavelet packet base such that f (t) corresponds to a wavelet packet series, wherein x k Represents the kth wavelet packet signal, where k=2 N -1；
S23: acquiring a node with the minimum evaluation function value in the multi-layer wavelet packet signal and marking the node as the first target power P PVObj (t)。
To facilitate understanding how the node with the smallest evaluation function value is obtained, the step S23 is further refined, as shown in fig. 3, including:
s231: acquiring a first power track sequence: x is x e ＝{x e1 ,x e2 …x em -a }; preferably, the first power track sequence is defined as a photovoltaic power generation power optimal fluctuation rate track sequence with fluctuation of photovoltaic power not exceeding the photovoltaic grid-connected national standard in any time period. Preferably, the first power trace sequence is capable of reflecting the overall trend of the output power.
S232: acquiring an evaluation function M for evaluating the approach degree of the wavelet packet base and the first power track sequence; preferably, the evaluation function M has additivity, namely:
M({x 1 })＝M(x 1 )，M({x 2 })＝M(x 2 )…,M({x k })＝M(x k )，
therefore, the evaluation function value after the combination and reconstruction of any wavelet packet signal sub-series is equal to the superposition of the evaluation function values of the sub-sequences before the reconstruction, and the evaluation function with additive property can effectively reduce the calculated amount and improve the operation speed and the operation efficiency of the algorithm.
S233: selecting different wavelet packet bases, starting from the decomposition of the first layer wavelet packet base, calculating the evaluation function value of the father node and the evaluation function value of the child node untilTo the node that acquired the smallest evaluation function value. Preferably, the parent node is defined as an upper node, and the child node is defined as a lower node. Specifically, as shown in fig. 9, the evaluation function values of the parent node and the child node are compared, and if the evaluation function value of the parent node is greater than the evaluation function value of the child node, the next-layer wavelet packet decomposition is continued. Comparing the evaluation function values of the father node and the child node, if the evaluation function value of the father node is smaller than the evaluation function value of the child node, marking the father node as the target power value after the light Fu Gonglv is stabilized as P PVObj (t)。
The traditional filtering algorithm and wavelet packet decomposition algorithm cannot distribute respective output according to the fluctuation characteristics of different photovoltaics and the characteristics of the energy absorption device due to frequency division and layering fixation, so that the stabilizing effect is poor. The improved novel wavelet packet decomposition algorithm disclosed by the invention comprehensively considers the characteristics and boundary conditions of each wavelet packet decomposition algorithm by introducing an evaluation function, and has the advantages of self-adaptive distribution of output force and good stabilizing effect.
To facilitate understanding how the first power track sequence is acquired, the step S231, as shown in fig. 4, further includes:
s2311: collecting the photovoltaic power signal f (t) of a plurality of prediction periods to generate a sampling sequence x s ＝{x s1 ,x s2 …x sn }；
S2312: acquiring a first power track function formed by the sampling sequence of adjacent prediction periods
Preferably, taking this embodiment as an example, the present invention defines the photovoltaic power fluctuation as a first power trace as not exceeding 5%. Wherein P is N Defined as the rated power of the photovoltaic power generation,
defined as the fluctuation of photovoltaic power within one minute of 5% of its rated capacity, T S Is defined as a unit time period;
s2313: generating a second power trajectory function by cumulatively summing the plurality of first power trajectory functions over a plurality of prediction periods:
wherein each calculation is a new P i (t) reassigning x si+1 ＝P i (iT s ) Refresh x s A sequence;
s2314: generating the first power track sequence by performing discrete point taking on the second power track function: x is x e ＝{x e1 ,x e2 …x em When m is defined as the number of discrete points selected equidistantly.
Further, as shown in fig. 5, the step S3 includes:
s31: obtaining a second target power f 1 (t) and generating a second power track sequence x e_ht ＝{x e_ht1 ,x e_ht2 …x e_htm And (f), where f 1 (t) is defined as the photovoltaic power that needs to be stabilized by the photovoltaic stabilizing unit: f (f) 1 (t)＝f(t)-P PVObj (t)；
S32: calculating the second target power through a novel wavelet packet basis decomposition algorithm and generating an optimal wavelet packet signal P HS_Obj (t)；
S33: based on the optimal wavelet packet signal P HS_Obj (t) and said second power trace sequence x e_ht ＝{x e_ht1 ,x e_ht2 …x e_htm Generating a first output power P HSObj (t)；
S34: based on the optimal wavelet packet signal P HS_Obj (t), the photovoltaic power signal f (t) and the first target power P HSObj (t) generating a second output power P FSC (t)；
S35: based on the first output power P HSObi (t) and the second output power P FSC (t) generating the scheduling signal.
Specifically, a second target power definition f is first defined 1 (t)＝f(t)-P PVObj (t) and a second workRate trace sequence x e_ht ＝{x e_ht1 ,x e_ht2 …x e_htm }；
Calculating (i-1) T S ～iT S Is a second power trace function of (a):
wherein i=1, 2 … n;
when the cascade hydropower station participates in stabilizing the photovoltaic power, according to the dynamic response characteristic of the cascade hydropower station, the maximum climbing rate of the regulated power of the cascade hydropower station does not exceed b: />
Calculating 0 to (n-1) T S Generating x by discrete point taking with optimized fluctuation power track function e_ht ＝x eh -P bast (t)。
Calculating the first output power P HSObj (t)＝P base (t)+P HS_Obj (t) calculating a second output power P FSC (t)＝f(t)-P PVObj (t)-P HS_Obj (t)。
Accordingly, as shown in fig. 6, the present invention provides a photovoltaic stabilization system based on a novel wavelet packet-based decomposition algorithm, including: the photovoltaic power generation unit is used for acquiring the short-time photovoltaic prediction data and generating a photovoltaic fluctuation rate; the control center calculates the photovoltaic fluctuation rate to generate a first target power through a novel wavelet packet basis decomposition algorithm, and generates a scheduling signal through the first target power; and the photovoltaic stabilizing unit is used for receiving the scheduling signal and restraining photovoltaic power fluctuation.
Further, the photovoltaic stabilization unit includes: a first photovoltaic stabilizing unit 3, configured to receive a first output power of the scheduling signal, and capable of suppressing the photovoltaic power fluctuation in a larger range; and the second photovoltaic stabilizing unit 4 is used for receiving the second output power of the scheduling signal and can quickly restrain the photovoltaic power fluctuation in a smaller range. The first photovoltaic stabilizing unit 3 may be an energy storage unit such as a cascade hydropower station capable of suppressing power fluctuation in a large range, and the second photovoltaic stabilizing unit 4 may be an energy storage unit such as an FSC pumped storage power station capable of rapidly suppressing power fluctuation in a small range. Preferably, the FSC pumped storage power station and the cascade hydropower station are arranged to stabilize the fluctuation of the output power of the photovoltaic power station, and the defects of the FSC pumped storage power station and the cascade hydropower station are complemented by utilizing the respective advantages, so that the light and water discarding phenomenon can be reduced while a better stabilizing effect is realized.
It should be noted that, although only the first photovoltaic stabilizing unit 3 and the second photovoltaic stabilizing unit 4 are shown in the present invention, the photovoltaic stabilizing units of the present invention are not limited to the first photovoltaic stabilizing unit 3 and the second photovoltaic stabilizing unit 4, and in order to ensure the photovoltaic stabilizing effect, the photovoltaic stabilizing units may be formed by a plurality of photovoltaic stabilizing devices, and any photovoltaic stabilizing system formed by using the photovoltaic stabilizing method of the present invention falls within the protection scope of the present invention.
Further, as shown in fig. 7, the control center 1 includes: the first processing unit 5: for receiving the photovoltaic fluctuation rate and transmitting the scheduling signal to the photovoltaic stabilization unit; the second processing unit 6: the method comprises the steps of performing the novel wavelet packet decomposition operation and generating the scheduling signal; memory sharing unit 7: the photovoltaic control system is used for storing historical data such as the photovoltaic fluctuation rate and the scheduling signal and establishing communication connection between the first processing unit and the second processing unit. The control center 1 may be configured by an EMS energy control system, as shown in fig. 8, the first processing unit 5 may be configured by an FPGA processor, the second processing unit 6 may be configured by a DSP processor, and both the first processing unit 5 and the second processing unit 6 may establish a communication connection with the memory sharing unit 7 through a serial high-speed interconnection interface (SRIO).
For ease of understanding, as shown in fig. 10, taking this embodiment as an example, the control center 1 is an energy management system EMS, the photovoltaic power generation unit 2 is a centralized photovoltaic power station of 100MW, the first photovoltaic stabilizing unit 3 is a cascade hydropower station of 150MW, and the second photovoltaic stabilizing unit 4 is an FSC pumped storage power station of 5 MW. The common connection point of the voltage of the alternating current bus is 220KV, and the voltage of the step-up transformer is increased to 50KV, so that electric power is transmitted to a power grid. The FSC pumped storage power station consists of a full-power converter, a synchronous generator and a water pump turbine. Energy is transferred between the motor stator and the grid through the full power converter. Specifically, in the power generation mode, the pump turbine is operated in a variable speed manner according to operating conditions and power requirements. In addition, the full-power converter converts electric energy with different voltage frequencies and phases into electric energy identical to the power grid through the AC/DC/AC converter. In contrast, in the power mode, the power directions are opposite, the output voltage frequency is regulated by the full-power converter, the rotating speed of the water wheel of the water pump is accurately controlled, and the power is absorbed from the power grid. The relation between the rotation speed and the output power is as follows:
P＝Kf(n 3 )；
wherein P is the absorption power of the water pump, n is the rotation speed of the rotor of the synchronous motor, f is the current frequency of the stator, P is the pole pair number of the motor, and k is the specific coefficient. Because the full-power converter completely isolates the motor from the power grid, the pumped storage power station can realize stepless speed regulation, the range and the speed of power regulation are improved, and the fluctuation of active power of a power system is well restrained. The energy management system EMS is a control center of the cascade water light accumulation complementary power generation system, and is used for collecting photovoltaic output power and photovoltaic predicted power, running an algorithm and sending a scheduling power instruction to a cascade hydropower station and a variable-speed pumped storage power station. After the cascade hydropower station receives the dispatching power instruction, the total power instruction is distributed to each stage of hydropower station according to external working conditions such as actual water head, water flow and the like.
Specifically, as shown in fig. 11, taking this simulation data as an example, when the power base value of the cascade hydropower station is 60MW, the maximum fluctuation amount before the stabilization is 19.08MW, the average fluctuation amount is 5.34MW, the target is 24.84% not reached, the maximum fluctuation amount 1 minute after the stabilization is 1.9MW, the average fluctuation amount is 0.67MW, and the target for the stabilization is not reached to 0.3%. The following characteristics of the actual power value and the target power value of the FSC pumped storage power station and the actual power value and the target power value of the cascade hydropower station are good, and the average accumulated errors in one minute are respectively as follows: 1.17MW, 2.38MW. Various performance indexes are shown in the figure, and compared with various performance indexes of a common filtering algorithm and a wavelet packet decomposition algorithm, the improved wavelet packet decomposition algorithm has obviously improved stabilizing effect.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that the above-mentioned preferred embodiment should not be construed as limiting the invention, and the scope of the invention should be defined by the appended claims. It will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the spirit and scope of the invention, and such modifications and adaptations are intended to be comprehended within the scope of the invention.
Claims (5)
1. A novel wavelet packet based decomposition-based photovoltaic stabilization method, comprising:
s1: acquiring short-time photovoltaic prediction data and generating photovoltaic fluctuation rate;
s2: generating a first target power by calculating the photovoltaic fluctuation rate; comprising the following steps:
s21: generating a photovoltaic power signal based on the photovoltaic fluctuation rate;
s22: performing wavelet packet-based decomposition on the photovoltaic power signal and generating a multi-layer wavelet packet signal;
s23: acquiring a node with the minimum evaluation function value in the multi-layer wavelet packet signal and marking the node as the first target power; comprising the following steps:
s231: acquiring a first power track sequence; comprising the following steps:
s2311: collecting the photovoltaic power signals of a plurality of prediction periods to generate a sampling sequence;
s2312: acquiring a first power track function formed by the sampling sequences of adjacent prediction periods;
s2313: accumulating and summing the plurality of first power track functions to generate a second power track function;
s2314: generating the first power track sequence based on the second power track function;
s232: acquiring an evaluation function based on the first power track sequence;
s233: selecting different wavelet packet signals to obtain a plurality of layers of low-frequency-band wavelet packet signals;
s234: acquiring a node with the minimum evaluation function value;
s3: processing the first target power and generating a scheduling signal; comprising the following steps:
s31: acquiring a second target power and generating a second power track sequence;
s32: calculating the second target power through novel wavelet packet basis decomposition and generating an optimal wavelet packet signal;
s33: generating a first output power based on the optimal wavelet packet signal and the second power trace sequence;
s34: generating a second output power based on the optimal wavelet packet signal, the photovoltaic power signal, and the first target power;
s35: the scheduling signal is generated based on the first output power and the second output power.
2. The method of claim 1, further comprising determining whether the photovoltaic fluctuation rate is above a grid-tie criteria, wherein,
under the condition that the photovoltaic fluctuation rate does not exceed a grid-connected standard, the photovoltaic power generation unit (2) is connected with the grid;
in case the photovoltaic fluctuation rate exceeds the grid-connected standard, the control center (1) generates a scheduling signal by calculating the photovoltaic fluctuation rate.
3. A photovoltaic stabilization system based on a novel wavelet packet basis decomposition algorithm, comprising:
the photovoltaic power generation unit is used for acquiring the short-time photovoltaic prediction data and generating a photovoltaic fluctuation rate;
the control center calculates the photovoltaic fluctuation rate to generate a first target power through a novel wavelet packet basis decomposition algorithm, and comprises the following steps:
s21: generating a photovoltaic power signal based on the photovoltaic fluctuation rate;
s22: performing wavelet packet-based decomposition on the photovoltaic power signal and generating a multi-layer wavelet packet signal;
s23: acquiring a node with the minimum evaluation function value in the multi-layer wavelet packet signal and marking the node as the first target power; comprising the following steps:
s231: acquiring a first power track sequence; comprising the following steps:
s2311: collecting the photovoltaic power signals of a plurality of prediction periods to generate a sampling sequence;
s2312: acquiring a first power track function formed by the sampling sequences of adjacent prediction periods;
s2313: accumulating and summing the plurality of first power track functions to generate a second power track function;
s2314: generating the first power track sequence based on the second power track function;
s232: acquiring an evaluation function based on the first power track sequence;
s233: selecting different wavelet packet signals to obtain a plurality of layers of low-frequency-band wavelet packet signals;
s234: acquiring a node with the minimum evaluation function value;
generating a scheduling signal with a first target power, comprising:
s31: acquiring a second target power and generating a second power track sequence;
s32: calculating the second target power through novel wavelet packet basis decomposition and generating an optimal wavelet packet signal;
s33: generating a first output power based on the optimal wavelet packet signal and the second power trace sequence;
s34: generating a second output power based on the optimal wavelet packet signal, the photovoltaic power signal, and the first target power;
s35: generating the scheduling signal based on the first output power and the second output power;
and the photovoltaic stabilizing unit is used for receiving the scheduling signal and restraining photovoltaic power fluctuation.
4. The photovoltaic stabilization system according to claim 3, wherein the photovoltaic stabilization unit comprises:
a first photovoltaic stabilizing unit: a first output power for receiving the scheduling signal capable of suppressing the photovoltaic power fluctuation over a wide range;
a second photovoltaic stabilizing unit: the second output power for receiving the scheduling signal enables rapid suppression of the photovoltaic power fluctuation in a smaller range.
5. The photovoltaic stabilization system of claim 4, wherein the control center comprises:
a first processing unit: for receiving the photovoltaic fluctuation rate and transmitting the scheduling signal to the photovoltaic stabilization unit;
a second processing unit: the method comprises the steps of performing the novel wavelet packet decomposition operation and generating the scheduling signal;
memory sharing unit: the photovoltaic power generation device is used for storing historical data of the photovoltaic fluctuation rate and the scheduling signal and establishing communication connection between the first processing unit and the second processing unit.
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