CN116345428A - Fluctuation power stabilizing method and system based on hydrogen-electricity hybrid energy storage system - Google Patents

Abstract

The invention provides a fluctuation power stabilizing method and system based on a hydrogen-electricity hybrid energy storage system, which are used for establishing the hydrogen-electricity hybrid energy storage system, and comprises a supercapacitor array, a hydrogen energy storage unit, an auxiliary power supply and a converter, wherein the hydrogen energy storage unit comprises an electrolytic tank, a fuel cell and a hydrogen storage tank; performing frequency analysis on the original rapid fluctuation power through empirical mode decomposition and Hilbert-Huang transform to obtain a sliding range of demarcation frequency, distributing fluctuation power with frequency higher than the demarcation frequency to a supercapacitor array, and distributing fluctuation power with frequency lower than the demarcation frequency to a hydrogen energy storage unit; calculating the discharge power of an auxiliary power supply based on the power requirements of the supercapacitor array and the hydrogen energy storage unit to compensate for the loss power; and setting a sliding adjustment rule, and performing sliding adjustment on the demarcation frequency to adjust the distribution of the fluctuation power and improve the power absorption rate.

Description

Fluctuation power stabilizing method and system based on hydrogen-electricity hybrid energy storage system

Technical Field

The invention relates to the technical field of hybrid energy storage of electric power systems, in particular to a fluctuation power stabilizing method and system based on a hydrogen-electricity hybrid energy storage system.

Background

In recent years, with the progress of shortage of global fossil energy and the strong advancement of environmental protection, global energy structures are undergoing significant changes, and renewable energy sources represented by wind power and photovoltaic are rapidly developing. However, the continuous increase of the scale of the wind power photovoltaic installation brings great economic benefit and environmental benefit, and simultaneously brings great challenges to the power grid. Renewable energy power generation is greatly affected by natural conditions such as wind speed, illumination, temperature and the like, output power has strong volatility, intermittence and randomness, and cannot be completely connected to the grid for consumption, so that certain energy waste is caused.

The energy storage system is installed near the wind power plant and the photovoltaic power station, and the method becomes an important means for stabilizing the power generation fluctuation of renewable energy sources. However, various working conditions which occur when wind power fluctuation is stabilized are difficult to be handled by single energy storage, a hybrid energy storage system is mostly adopted at present, a great deal of researches are conducted on the hybrid energy storage system consisting of a storage battery and a super capacitor, and the combination has the advantages of good variable working condition characteristics and easiness in control. However, when the power is subjected to rapid fluctuation, the storage battery is short in cycle life, frequent in daily maintenance and environment pollution risk, and the cost of the super capacitor is high independently, so that the super capacitor is insufficient to cope with different working conditions. In addition, the research on hybrid energy storage systems is mainly configured with capacity, but under the condition of determining parameters such as system capacity, how to improve the fluctuation power stabilizing effect by an operation control method is rarely mentioned, which is very important in engineering application.

Disclosure of Invention

The invention provides a fluctuation power stabilizing method and system based on a hydrogen-electricity hybrid energy storage system, which are used for solving the technical problem of improving the fluctuation power stabilizing effect under the condition of determining parameters such as system capacity and the like.

In order to solve the technical problems, the invention provides a fluctuation power stabilizing method and system based on a hydrogen-electricity hybrid energy storage system, comprising the following steps:

step S1: the method comprises the steps of establishing a hydrogen-electricity hybrid energy storage system, wherein the hydrogen-electricity hybrid energy storage system comprises a supercapacitor array, a hydrogen energy storage unit, an auxiliary power supply and a converter, and the hydrogen energy storage unit comprises an electrolytic tank, a fuel cell and a hydrogen storage tank;

step S2: performing frequency analysis on the original rapid fluctuation power through empirical mode decomposition and Hilbert-Huang transform to obtain a sliding range of demarcation frequency, distributing fluctuation power with frequency higher than the demarcation frequency to a supercapacitor array, and distributing fluctuation power with frequency lower than the demarcation frequency to a hydrogen energy storage unit;

step S3: calculating the discharge power of an auxiliary power supply based on the power requirements of the supercapacitor array and the hydrogen energy storage unit to compensate for the loss power;

step S4: and setting a sliding adjustment rule, and performing sliding adjustment on the demarcation frequency to adjust the distribution of the fluctuation power and improve the power absorption rate.

Preferably, the empirical mode decomposition in step S2 is expressed as:

wherein P is _rf (t) represents the rapid fluctuation power at the time t, n represents the number of the set eigenmode components, and c _i Representing the eigenmode component, r _n Representing the residual component.

Preferably, the hilbert-yellow transform in step S2 comprises the steps of:

step S21: the eigenvalue component c _i Convolving with 1/pi t, the expression is:

wherein τ represents a concept of time;

step S22: c (t) and H [ c (t) ] are combined to analyze the signal z (t), and the expression is:

wherein a (t) and

respectively representing the instantaneous amplitude and the instantaneous phase of the signal;

step S23: calculating instantaneous frequency:

preferably, in step S3, the discharge of the auxiliary power supply is calculatedPower P _m The expression of (t) is:

wherein P is _m,sc (t) represents auxiliary power supply output power requirements, P, generated based on supercapacitor array operating states _m,hu (t) is the auxiliary power supply output power demand, alpha, generated based on the operating conditions of the hydrogen unit _i For the proportionality coefficient of each state quantity, P _sc (t)、P _el (t) and P _fc (t) actual operating power, SOC, of the supercapacitor, the electrolyzer and the fuel cell, respectively _sc (t) and LOH _hst (t) the state of charge of the supercapacitor array and the hydrogen storage level of the hydrogen storage tank, respectively.

Preferably, the calculation formula of the charge state of the supercapacitor array is as follows:

wherein E is _sc,r Representing the rated capacity of the super capacitor array, E _sc And (t) represents the residual electric quantity in the super capacitor at the moment t.

Preferably, the calculation formula of the hydrogen storage level of the hydrogen storage tank is:

wherein E is _hst,r Indicating the rated capacity of the hydrogen storage tank E _hst And (t) represents the residual hydrogen amount in the hydrogen storage tank at the time t.

Preferably, the sliding adjustment rule includes:

1) When P _sc (t)＜P _sc,max 、SOC _sc (t)＜SOC _sc,max 、P _el (t)>P _el,r When the boundary frequency is regulated down;

2) When P _sc (t)＜P _sc,max 、SOC _sc (t)＜SOC _sc,max 、P _el (t)>0、LOH _hst (t)＞LOH _hst,max When the boundary frequency is regulated down;

3) When P _sc (t)＞-P _sc,max 、SOC _sc (t)＞SOC _sc,min 、P _fc (t)>P _fc,r When the boundary frequency is regulated down;

4) When P _sc (t)＞-P _sc,max 、SOC _sc (t)＞SOC _sc,min 、P _fc (t)>0、LOH _hst (t)＜LOH _hst,min When the boundary frequency is regulated down;

5) When P _sc (t)＞P _sc,max 、P _el (t)＜P _el,r 、LOH _hst (t)＜LOH _hst,max When the boundary frequency is increased;

6) When P _sc (t)＞0、SOC _sc (t)＞SOC _sc,max 、P _el (t)＜P _el,r 、LOH _hst (t)＜LOH _hst,max When the boundary frequency is increased;

7) When P _sc (t)＜-P _sc,max 、P _fc (t)＜P _fc,r 、LOH _hst (t)＞LOH _hst,min When the boundary frequency is increased;

8) When P _sc (t)＜0、SOC _sc (t)＜SOC _sc,max 、P _fc (t)＜P _fc,r 、LOH _hst (t)＞LOH _hst,min When the boundary frequency is increased;

P _sc (t)、P _el (t)、P _fc (t) represents the actual operating power, SOC of the super capacitor array, the electrolytic cell and the fuel cell respectively _sc (t) represents the state of charge of the supercapacitor array, LOH _hst (t) represents the hydrogen storage level of the hydrogen storage tank, P _sc,max Representing the maximum charging power of the super capacitor array, -P _sc,max Represents the maximum discharge power of the super capacitor array, P _el,r And P _fc,r Respectively represents rated power and SOC of an electrolytic cell and a fuel cell _sc,max And SOC (System on chip) _sc,min Respectively represent the upper limit and the lower limit of the charge state of the super capacitor, LOH _hst,max And LOH (Low-Density parity) _hst,min Respectively represent the upper limit of the hydrogen storage level of the hydrogen storage tankAnd a lower limit.

Preferably, the step frequency of the sliding adjustment is set to be 1×10 ^-6 Hz。

The invention also provides a fluctuation power stabilizing system based on the hydrogen-electricity hybrid energy storage system, which comprises the hydrogen-electricity hybrid energy storage system, a frequency analysis module, an auxiliary power supply power compensation module and a sliding distribution adjustment module;

the hydrogen-electricity hybrid energy storage system comprises a super capacitor array, a hydrogen energy storage unit, an auxiliary power supply and a converter, wherein the hydrogen energy storage unit comprises an electrolytic tank, a fuel cell and a hydrogen storage tank;

the frequency analysis module is used for carrying out frequency analysis on the original rapid fluctuation power through empirical mode decomposition and Hilbert-Huang transform to obtain a sliding range of the demarcation frequency;

the auxiliary power supply power compensation module is used for adjusting the discharge power of the auxiliary power supply so as to compensate the loss power;

the sliding distribution adjusting module is used for carrying out sliding adjustment on the demarcation frequency according to a set sliding adjustment rule.

Preferably, the sliding adjustment rule set by the sliding allocation adjustment module includes:

1) When P _sc (t)＜P _sc,max 、SOC _sc (t)＜SOC _sc,max 、P _el (t)>P _el,r When the boundary frequency is regulated down;

2) When P _sc (t)＜P _sc,max 、SOC _sc (t)＜SOC _sc,max 、P _el (t)>0、LOH _hst (t)＞LOH _hst,max When the boundary frequency is regulated down;

3) When P _sc (t)＞-P _sc,max 、SOC _sc (t)＞SOC _sc,min 、P _fc (t)>P _fc,r When the boundary frequency is regulated down;

4) When P _sc (t)＞-P _sc,max 、SOC _sc (t)＞SOC _sc,min 、P _fc (t)>0、LOH _hst (t)＜LOH _hst,min When the boundary frequency is regulated down;

5) When P _sc (t)＞P _sc,max 、P _el (t)＜P _el,r 、LOH _hst (t)＜LOH _hst,max When the boundary frequency is increased;

6) When P _sc (t)＞0、SOC _sc (t)＞SOC _sc,max 、P _el (t)＜P _el,r 、LOH _hst (t)＜LOH _hst,max When the boundary frequency is increased;

7) When P _sc (t)＜-P _sc,max 、P _fc (t)＜P _fc,r 、LOH _hst (t)＞LOH _hst,min When the boundary frequency is increased;

8) When P _sc (t)＜0、SOC _sc (t)＜SOC _sc,max 、P _fc (t)＜P _fc,r 、LOH _hst (t)＞LOH _hst,min When the boundary frequency is increased;

P _sc (t)、P _el (t)、P _fc (t) represents the actual operating power, SOC of the super capacitor array, the electrolytic cell and the fuel cell respectively _sc (t) represents the state of charge of the supercapacitor array, LOH _hst (t) represents the hydrogen storage level of the hydrogen storage tank, P _sc,max Representing the maximum charging power of the super capacitor array, -P _sc,max Represents the maximum discharge power of the super capacitor array, P _el,r And P _fc,r Respectively represents rated power and SOC of an electrolytic cell and a fuel cell _sc,max And SOC (System on chip) _sc,min Respectively represent the upper limit and the lower limit of the charge state of the super capacitor, LOH _hst,max And LOH (Low-Density parity) _hst,min Indicating the upper limit and the lower limit of the hydrogen storage level of the hydrogen storage tank, respectively.

The beneficial effects of the invention at least comprise: by establishing the hydrogen-electricity hybrid energy storage system, adopting an auxiliary power supply to perform power compensation, distributing the rapid fluctuation power by setting the demarcation frequency, and simultaneously, by adaptively sliding the demarcation frequency, the rapid fluctuation power absorption rate of the hydrogen-electricity hybrid energy storage system under the premise of unchanged capacity is improved, and the normal operation of each element of energy storage is ensured and the fluctuation power is effectively stabilized.

Drawings

FIG. 1 is a flow chart of a method according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a hybrid hydro-electric energy storage system according to an embodiment of the invention;

FIG. 3 is a schematic diagram of a fast fluctuating power of an embodiment of the present invention;

FIG. 4 is a schematic diagram of a Hilbert spectrum according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of the super capacitor array operating domain and the hydrogen storage unit operating domain with the demarcation frequency not slid and the auxiliary power not activated;

FIG. 6 is a schematic diagram of the untreated power of FIG. 5;

FIG. 7 is a schematic diagram of the super capacitor array operating domain and the hydrogen storage unit operating domain when the demarcation frequency is sliding and the auxiliary power source is activated;

FIG. 8 is a schematic diagram of the state of charge of the supercapacitor array and the capacity of the hydrogen storage tank when the auxiliary power supply is started and the boundary frequency is slid;

FIG. 9 is a schematic diagram of auxiliary power supply motion power and demarcation frequency slip.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is evident that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by a person skilled in the art without any inventive effort, are intended to be within the scope of the present invention, based on the embodiments of the present invention.

As shown in fig. 1, the embodiment of the invention provides a method and a system for stabilizing fluctuation power based on a hydrogen-electricity hybrid energy storage system, which comprise the following steps:

step S1: the establishment of a hydrogen-electricity hybrid energy storage system is shown in fig. 2, and comprises a supercapacitor array, a hydrogen energy storage unit, an auxiliary power supply and a converter, wherein the hydrogen energy storage unit comprises an electrolytic tank, a fuel cell and a hydrogen storage tank.

The super capacitor array is responsible for processing a high-frequency part in the rapid fluctuation power, absorbing positive power to store electric energy and discharging electric energy at a negative value.

And the hydrogen energy storage unit is responsible for processing the middle-low frequency part of the rapid fluctuation power. The electrolyzer absorbs positive power to produce hydrogen, stores the produced hydrogen in the hydrogen storage tank, and supplies the hydrogen to the fuel cell for hydrogen consumption and discharge when negative power compensation is needed.

Fast fluctuating power, representing the difference between the original output power of renewable energy generation and the allowed grid-tie power, or other fluctuating power generated in the power system that varies between positive and negative values, is typically on the order of hours and minutes.

The stabilization means that positive power in the rapid fluctuation power is absorbed by the hybrid energy storage system to store energy, and negative power is discharged by the hybrid energy storage system to compensate energy.

Step S2: and carrying out frequency analysis on the original rapid fluctuation power through empirical mode decomposition and Hilbert-Huang transform to obtain a sliding range of demarcation frequency, distributing fluctuation power with frequency higher than the demarcation frequency to the supercapacitor array, and distributing fluctuation power with frequency lower than the demarcation frequency to the hydrogen energy storage unit.

Specifically, empirical mode decomposition and Hilbert-Huang transform are a signal processing method, in which the Hilbert-Huang transform requires first performing empirical mode decomposition on the original signal to obtain intrinsic mode components (IMF) c in different frequency ranges _i And residual component r _n I is the number of preset intrinsic mode components IMF, c _i One-to-one correspondence with IMFs.

The empirical mode decomposition is expressed as:

wherein P is _rf (t) represents the rapid fluctuation power at the time t, n represents the number of the set eigenmode components, and c _i Representing the eigenmode component, r _n Representing the residual component.

The hilbert-yellow transform comprises the steps of:

step S21: the eigenvalue component c _i And 1/pit is convolved, and the expression is:

wherein τ represents a concept of time;

step S22: c (t) and H [ c (t) ] are combined to analyze the signal z (t), and the expression is:

wherein a (t) and

respectively representing the instantaneous amplitude and the instantaneous phase of the signal;

step S23: calculating instantaneous frequency:

step S3: and calculating the discharge power of the auxiliary power supply based on the power requirements of the supercapacitor array and the hydrogen energy storage unit so as to compensate the loss power.

The auxiliary power supply is used for compensating the internal operation loss of the hybrid energy storage system. Typically, the fluctuating power requires that the total charge and total discharge handled by the hybrid energy storage system be substantially equal over a period of time. However, when the hybrid energy storage system works, heat is generated inside, a part of electric quantity is wasted due to the main loss, and the fuel cell is most serious, so that the actual charging quantity cannot meet the requirement of the discharging quantity. Therefore, an auxiliary power supply is designed in the system to maintain the charge-discharge balance of the hybrid energy storage system.

The discharge power of the auxiliary power supply is determined by the running state of the hybrid energy storage system, and the discharge power P thereof _m The expression of (t) is:

wherein P is _m,sc (t) represents auxiliary power supply output power requirements, P, generated based on supercapacitor array operating states _m,hu (t) is the auxiliary power supply output power demand, alpha, generated based on the operating conditions of the hydrogen unit _sc,i Scaling factor, alpha, representing state quantity of supercapacitor array _hu,i A proportionality coefficient representing the state quantity of the hydrogen unit, P _sc (t)、P _el (t) and P _fc (t) actual operating power, SOC, of the supercapacitor, the electrolyzer and the fuel cell, respectively _sc (t) and LOH _hst (t) the state of charge of the supercapacitor array and the hydrogen storage level of the hydrogen storage tank, respectively.

In the embodiment of the invention, the SOC of the super capacitor array _sc The calculation formula of (t) is:

wherein E is _sc,r Representing the rated capacity of the super capacitor array, E _sc (t) represents the residual electric quantity in the super capacitor at the moment t;

hydrogen storage level LOH of hydrogen storage tank _hst The calculation formula of (t) is:

wherein E is _hst,r Indicating the rated capacity of the hydrogen storage tank E _hst And (t) represents the residual hydrogen amount in the hydrogen storage tank at the time t.

Step S4: and setting a sliding adjustment rule, and performing sliding adjustment on the demarcation frequency to adjust the distribution of the fluctuation power and improve the power absorption rate.

Specifically, the demarcation frequency f _c (t) the time is required to be changed according to the running state so as to meet the requirements of different working conditions; thus, the sliding ranges [0, f of the demarcation frequencies obtained according to step S2 _c,max ]Boundary frequency f _c (t) will be based on hybrid energy storageThe working condition of the internal equipment of the system is [0, f _c,max ]Sliding in section f _c,max The frequency representing the power allocated to the hydrogen storage unit is not allowed to be higher than this value.

In the embodiment of the invention, the step frequency of the sliding adjustment is set to be 1 multiplied by 10 ^-6 Hz to achieve the purpose of accurate adjustment, the slip adjustment rules include:

1) When P _sc (t)＜P _sc,max 、SOC _sc (t)＜SOC _sc,max 、P _el (t)>P _el,r When the boundary frequency is regulated down;

2) When P _sc (t)＜P _sc,max 、SOC _sc (t)＜SOC _sc,max 、P _el (t)>0、LOH _hst (t)＞LOH _hst,max When the boundary frequency is regulated down;

3) When P _sc (t)＞-P _sc,max 、SOC _sc (t)＞SOC _sc,min 、P _fc (t)>P _fc,r When the boundary frequency is regulated down;

4) When P _sc (t)＞-P _sc,max 、SOC _sc (t)＞SOC _sc,min 、P _fc (t)>0、LOH _hst (t)＜LOH _hst,min When the boundary frequency is regulated down;

5) When P _sc (t)＞P _sc,max 、P _el (t)＜P _el,r 、LOH _hst (t)＜LOH _hst,max When the boundary frequency is increased;

6) When P _sc (t)＞0、SOC _sc (t)＞SOC _sc,max 、P _el (t)＜P _el,r 、LOH _hst (t)＜LOH _hst,max When the boundary frequency is increased;

7) When P _sc (t)＜-P _sc,max 、P _fc (t)＜P _fc,r 、LOH _hst (t)＞LOH _hst,min When the boundary frequency is increased;

8) When P _sc (t)＜0、SOC _sc (t)＜SOC _sc,max 、P _fc (t)＜P _fc,r 、LOH _hst (t)＞LOH _hst,min When the boundary frequency is increased;

P _sc (t)、P _el (t)、P _fc (t) represents the actual operating power, SOC of the super capacitor array, the electrolytic cell and the fuel cell respectively _sc (t) represents the state of charge of the supercapacitor array, LOH _hst (t) represents the hydrogen storage level of the hydrogen storage tank, P _sc,max Representing the maximum charging power of the super capacitor array, -P _sc,max Represents the maximum discharge power of the super capacitor array, P _el,r And P _fc,r Respectively represents rated power and SOC of an electrolytic cell and a fuel cell _sc,max And SOC (System on chip) _sc,min Respectively represent the upper limit and the lower limit of the charge state of the super capacitor, LOH _hst,max And LOH (Low-Density parity) _hst,min Indicating the upper limit and the lower limit of the hydrogen storage level of the hydrogen storage tank, respectively.

The reason for the sliding of the split frequency is that the characteristic that the super capacitor can process high-frequency fluctuation and simultaneously process low-frequency fluctuation is utilized, and a part of low-frequency power which is originally processed by the hydrogen energy storage unit is distributed to the super capacitor array for processing in the idle or low-power operation time period of the super capacitor array device, so that the hydrogen energy storage unit is helped to absorb the distributed power which cannot be executed. This portion of the distributed power that cannot be performed may be due to the distributed power being greater than the rated power of the device, or the hydrogen storage tank having a hydrogen storage level that reaches an upper or lower limit.

The invention also provides a fluctuation power stabilizing system based on the hydrogen-electricity hybrid energy storage system, which comprises the hydrogen-electricity hybrid energy storage system, a frequency analysis module, an auxiliary power supply power compensation module and a sliding distribution adjustment module;

the hydrogen-electricity hybrid energy storage system comprises a super capacitor array, a hydrogen energy storage unit, an auxiliary power supply and a converter, wherein the hydrogen energy storage unit comprises an electrolytic tank, a fuel cell and a hydrogen storage tank;

the frequency analysis module is used for carrying out frequency analysis on the original rapid fluctuation power through empirical mode decomposition and Hilbert-Huang transform to obtain a sliding range of the demarcation frequency;

the auxiliary power supply power compensation module is used for adjusting the discharge power of the auxiliary power supply so as to compensate the loss power;

the sliding distribution adjusting module is used for carrying out sliding adjustment on the demarcation frequency according to a set sliding adjustment rule.

The sliding adjustment rules set by the sliding allocation adjustment module are as follows:

list one

Specifically:

1) When P _sc (t)＜P _sc,max 、SOC _sc (t)＜SOC _sc,max 、P _el (t)>P _el,r When the boundary frequency is regulated down;

2) When P _sc (t)＜P _sc,max 、SOC _sc (t)＜SOC _sc,max 、P _el (t)>0、LOH _hst (t)＞LOH _hst,max When the boundary frequency is regulated down;

3) When P _sc (t)＞-P _sc,max 、SOC _sc (t)＞SOC _sc,min 、P _fc (t)>P _fc,r When the boundary frequency is regulated down;

4) When P _sc (t)＞-P _sc,max 、SOC _sc (t)＞SOC _sc,min 、P _fc (t)>0、LOH _hst (t)＜LOH _hst,min When the boundary frequency is regulated down;

5) When P _sc (t)＞P _sc,max 、P _el (t)＜P _el,r 、LOH _hst (t)＜LOH _hst,max When the boundary frequency is increased;

6) When P _sc (t)＞0、SOC _sc (t)＞SOC _sc,max 、P _el (t)＜P _el,r 、LOH _hst (t)＜LOH _hst,max When the boundary frequency is increased;

7) When P _sc (t)＜-P _sc,max 、P _fc (t)＜P _fc,r 、LOH _hst (t)＞LOH _hst,min When the boundary frequency is increased;

8) When P _sc (t)＜0、SOC _sc (t)＜SOC _sc,max 、P _fc (t)＜P _fc,r 、LOH _hst (t)＞LOH _hst,min When the boundary frequency is increased;

P _sc (t)、P _el (t)、P _fc (t) represents the actual operating power, SOC of the super capacitor array, the electrolytic cell and the fuel cell respectively _sc (t) represents the state of charge of the supercapacitor array, LOH _hst (t) represents the hydrogen storage level of the hydrogen storage tank, P _sc,max Representing the maximum charging power of the super capacitor array, -P _sc,max Represents the maximum discharge power of the super capacitor array, P _el,r And P _fc,r Respectively represents rated power and SOC of an electrolytic cell and a fuel cell _sc,max And SOC (System on chip) _sc,min Respectively represent the upper limit and the lower limit of the charge state of the super capacitor, LOH _hst,max And LOH (Low-Density parity) _hst,min Indicating the upper limit and the lower limit of the hydrogen storage level of the hydrogen storage tank, respectively.

The invention is further illustrated by the following specific examples:

as shown in fig. 3, the fluctuation amount of the wind power original power output in 43 minutes of a certain 2MW wind farm before grid connection needs to be stabilized, and the equipment parameters of the hydrogen-electricity hybrid energy storage system are shown in table 2 as the rapid fluctuation power input of the invention.

TABLE 2

Inputting fast fluctuating power into P _rf (t) performing empirical mode decomposition, setting the number of IMFs to 5, and obtaining intrinsic mode components IMF1-5 and residual component r _n The obtained IMF1 and IMF2 are main components, the duty ratio reaches 94.01%, and the frequency range is 1.27×10 ^-4 Hz to 1.39X10 ^-3 Hz, HHT analysis is carried out on IMF1 and IMF2 of main components to obtain Hilbert spectrum shown in figure 4.

From the frequencies of IMF1 and IMF2, it is known that the frequency is fastSpeed ripple power input P _rf Each positive and negative alternation of (t) is concentrated on the order of hours and minutes, and is analyzed in the graph to find that when the frequency is less than 2.77×10 ^-4 Almost vanishes at Hz, so let the maximum cut-off frequency f _c,max ＝2.77×10 ^-4 Hz, the bearing frequency of the hydrogen energy storage unit is lower than f _c The super capacitor array is responsible for power fluctuations in other frequency ranges.

Inputting fast fluctuating power into P _rf (t) performing empirical mode decomposition, setting the number of IMFs to 5, and obtaining intrinsic mode components IMF1-5 and residual component r _n The obtained IMF1 and IMF2 are main components, the duty ratio reaches 94.01%, and the frequency range is 1.27×10 ^-4 Hz to 1.39X10 ^-3 Hz. Therefore, only the IMF1 and IMF2 need to be subjected to HHT analysis to obtain the Hilbert spectrum, as shown in fig. 4.

Thus according to the maximum cut-off frequency f _c,max Super capacitor array operation domain P obtained by power distribution _sc,ref (t) and Hydrogen storage Unit operating Domain P _hu,ref (t) As shown in FIG. 5, the auxiliary power supply is not operated at this time, f _c Fixed as f _c,max Does not slide, P _sc,ref (t) positive value represents charging of super capacitor array, negative value represents discharging, and hydrogen energy storage unit P _hu,ref Positive values of (t) represent electrolyzer power consumption hydrogen production and negative values represent fuel cell power consumption hydrogen discharge. It can be seen that the frequency of power fluctuations assigned to the supercapacitor is significantly greater.

As is evident from a combination of table 2 and fig. 5, there is a peak power in the distribution domain that is much greater than the rated power of the energy storage device if the auxiliary power supply is not operating and f _c Without sliding, this portion of the power will not be processed, as shown in FIG. 6.

At this time, the auxiliary power supply P _m (t) auxiliary power supply, demarcation frequency f _c (t) adaptively sliding according to the established rule, the actual operation domain and the unexecuted operation domain of the super capacitor array and the hydrogen energy storage unit are as shown in FIG. 7, the energy storage device is operated within the rated power, and the unexecuted operation domain is at P _m,sc (t) and f _c Under the action of (t), the value is almost 0.

SOC of super capacitor array _sc (t) and LOH of Hydrogen storage tank _hst And (t) as shown in fig. 8, the upper limit and the lower limit are not broken through, and the charge-discharge balance of the hydrogen-electricity hybrid energy storage system is realized.

Auxiliary power supply P _m (t) and demarcation frequency f _c The variation of (t) is shown in FIG. 9, where P _m (t) display P respectively _m,sc (t) and P _m,hu (t). In the early stage of operation for rapid increase of SOC _sc (t) and LOH _hst (t)，P _m (t) is larger and then gradually decreases, and later in order to increase the energy storage level of the hybrid energy storage system, the energy storage level is rapidly pulled up again. Cut-off frequency f _c Variation of (t) compared to P _m (t) is more gradual, which also means that the large magnitude spike power for this month is less.

The invention effectively proved by the specific embodiment is applied to the scene that the model and the parameters of each device in the hybrid energy storage system are determined, stabilizes the effectiveness of the fluctuation power, and has good application prospect.

The foregoing embodiments may be combined in any way, and all possible combinations of the features of the foregoing embodiments are not described for brevity, but only the preferred embodiments of the invention are described in detail, which should not be construed as limiting the scope of the invention. The scope of the present specification should be considered as long as there is no contradiction between the combinations of these technical features.

It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims (10)

1. A fluctuation power stabilizing method and system based on a hydrogen-electricity hybrid energy storage system are characterized in that: the method comprises the following steps:

step S1: the method comprises the steps of establishing a hydrogen-electricity hybrid energy storage system, wherein the hydrogen-electricity hybrid energy storage system comprises a supercapacitor array, a hydrogen energy storage unit, an auxiliary power supply and a converter, and the hydrogen energy storage unit comprises an electrolytic tank, a fuel cell and a hydrogen storage tank;

step S2: performing frequency analysis on the original rapid fluctuation power through empirical mode decomposition and Hilbert-Huang transform to obtain a sliding range of demarcation frequency, distributing fluctuation power with frequency higher than the demarcation frequency to a supercapacitor array, and distributing fluctuation power with frequency lower than the demarcation frequency to a hydrogen energy storage unit;

step S3: calculating the discharge power of an auxiliary power supply based on the power requirements of the supercapacitor array and the hydrogen energy storage unit to compensate for the loss power;

step S4: and setting a sliding adjustment rule, and performing sliding adjustment on the demarcation frequency to adjust the distribution of the fluctuation power and improve the power absorption rate.

2. The method for stabilizing the fluctuation power of the hybrid energy storage system based on hydrogen and electricity according to claim 1, wherein the method comprises the following steps: the expression of the empirical mode decomposition in step S2 is:

wherein P is _rf (t) represents the rapid fluctuation power at the time t, n represents the number of the set eigenmode components, and c _i Representing the eigenmode component, r _n Representing the residual component.

3. The method for stabilizing the fluctuation power based on the hydrogen-electricity hybrid energy storage system according to claim 2, wherein the method comprises the following steps: the hilbert-yellow transform in step S2 comprises the steps of:

step S21: the eigenvalue component c _i Convolving with 1/pi t, the expression is:

wherein τ represents a concept of time;

step S22: c (t) and H [ c (t) ] are combined to analyze the signal z (t), and the expression is:

wherein a (t) and

respectively representing the instantaneous amplitude and the instantaneous phase of the signal;

step S23: calculating instantaneous frequency:

4. a method of stabilizing fluctuating power based on a hybrid hydro-electric energy storage system according to claim 3, characterized by: in step S3, the discharge power P of the auxiliary power supply is calculated _m The expression of (t) is:

wherein P is _m,sc (t) represents auxiliary power supply output power requirements, P, generated based on supercapacitor array operating states _m,hu (t) is the auxiliary power supply output power demand, alpha, generated based on the operating conditions of the hydrogen unit _i For the proportionality coefficient of each state quantity, P _sc (t)、P _el (t) and P _fc (t) actual operating power, SOC, of the supercapacitor, the electrolyzer and the fuel cell, respectively _sc (t) and LOH _hst (t) the state of charge of the supercapacitor array and the hydrogen storage level of the hydrogen storage tank, respectively.

5. The method for stabilizing the fluctuating power based on the hybrid hydrogen-electric energy storage system according to claim 4, wherein the method comprises the following steps: the calculation formula of the charge state of the super capacitor array is as follows:

wherein E is _sc,r Representing the rated capacity of the super capacitor array, E _sc And (t) represents the residual electric quantity in the super capacitor at the moment t.

6. The method for stabilizing the fluctuating power based on the hybrid hydrogen-electric energy storage system according to claim 4, wherein the method comprises the following steps: the calculation formula of the hydrogen storage level of the hydrogen storage tank is as follows:

wherein E is _hst,r Indicating the rated capacity of the hydrogen storage tank E _hst And (t) represents the residual hydrogen amount in the hydrogen storage tank at the time t.

7. The method for stabilizing the fluctuation power of the hybrid energy storage system based on hydrogen and electricity according to claim 1, wherein the method comprises the following steps: in step S4, the sliding adjustment rule includes:

1) When P _sc (t)＜P _sc,max 、SOC _sc (t)＜SOC _sc,max 、P _el (t)>P _el,r When the boundary frequency is regulated down;

2) When P _sc (t)＜P _sc,max 、SOC _sc (t)＜SOC _sc,max 、P _el (t)>0、LOH _hst (t)＞LOH _hst,max When the boundary frequency is regulated down;

3) When P _sc (t)＞-P _sc,max 、SOC _sc (t)＞SOC _sc,min 、P _fc (t)>P _fc,r When the boundary frequency is regulated down;

4) When P _sc (t)＞-P _sc,max 、SOC _sc (t)＞SOC _sc,min 、P _fc (t)>0、LOH _hst (t)＜LOH _hst,min When the boundary frequency is regulated down;

5) When P _sc (t)＞P _sc,max 、P _el (t)＜P _el,r 、LOH _hst (t)＜LOH _hst,max When the boundary frequency is increased;

6) When P _sc (t)＞0、SOC _sc (t)＞SOC _sc,max 、P _el (t)＜P _el,r 、LOH _hst (t)＜LOH _hst,max When the boundary frequency is increased;

7) When P _sc (t)＜-P _sc,max 、P _fc (t)＜P _fc,r 、LOH _hst (t)＞LOH _hst,min When the boundary frequency is increased;

8) When P _sc (t)＜0、SOC _sc (t)＜SOC _sc,max 、P _fc (t)＜P _fc,r 、LOH _hst (t)＞LOH _hst,min When the boundary frequency is increased;

P _sc (t)、P _el (t)、P _fc (t) represents the actual operating power, SOC of the super capacitor array, the electrolytic cell and the fuel cell respectively _sc (t) represents the state of charge of the supercapacitor array, LOH _hst (t) represents the hydrogen storage level of the hydrogen storage tank, P _sc,max Representing the maximum charging power of the super capacitor array, -P _sc,max Represents the maximum discharge power of the super capacitor array, P _el,r And P _fc,r Respectively represents rated power and SOC of an electrolytic cell and a fuel cell _sc,max And SOC (System on chip) _sc,min Respectively represent the upper limit and the lower limit of the charge state of the super capacitor, LOH _hst,max And LOH (Low-Density parity) _hst,min Indicating the upper limit and the lower limit of the hydrogen storage level of the hydrogen storage tank, respectively.

8. The method for stabilizing the fluctuating power based on the hydrogen-electricity hybrid energy storage system according to claim 8, wherein the method comprises the following steps: the step frequency of the sliding adjustment is set to be 1 multiplied by 10 ^-6 Hz。

9. A fluctuation power stabilizing method based on a hydrogen-electricity hybrid energy storage system is characterized by comprising the following steps of: the system comprises a hydrogen-electricity hybrid energy storage system, a frequency analysis module, an auxiliary power supply power compensation module and a sliding distribution adjustment module;

the hydrogen-electricity hybrid energy storage system comprises a super capacitor array, a hydrogen energy storage unit, an auxiliary power supply and a converter, wherein the hydrogen energy storage unit comprises an electrolytic tank, a fuel cell and a hydrogen storage tank;

the frequency analysis module is used for carrying out frequency analysis on the original rapid fluctuation power through empirical mode decomposition and Hilbert-Huang transform to obtain a sliding range of the demarcation frequency;

the auxiliary power supply power compensation module is used for adjusting the discharge power of the auxiliary power supply so as to compensate the loss power;

the sliding distribution adjusting module is used for carrying out sliding adjustment on the demarcation frequency according to a set sliding adjustment rule.

10. The surge power stabilization-based hybrid hydrogen-electric energy storage system of claim 9, wherein:

the sliding adjustment rule set by the sliding allocation adjustment module comprises:

1) When P _sc (t)＜P _sc,max 、SOC _sc (t)＜SOC _sc,max 、P _el (t)>P _el,r When the boundary frequency is regulated down;

2) When P _sc (t)＜P _sc,max 、SOC _sc (t)＜SOC _sc,max 、P _el (t)>0、LOH _hst (t)＞LOH _hst,max When the boundary frequency is regulated down;

3) When P _sc (t)＞-P _sc,max 、SOC _sc (t)＞SOC _sc,min 、P _fc (t)>P _fc,r When the boundary frequency is regulated down;

4) When P _sc (t)＞-P _sc,max 、SOC _sc (t)＞SOC _sc,min 、P _fc (t)>0、LOH _hst (t)＜LOH _hst,min When the boundary frequency is regulated down;

5) When P _sc (t)＞P _sc,max 、P _el (t)＜P _el,r 、LOH _hst (t)＜LOH _hst,max When the boundary frequency is increased;

6) When P _sc (t)＞0、SOC _sc (t)＞SOC _sc,max 、P _el (t)＜P _el,r 、LOH _hst (t)＜LOH _hst,max When the boundary frequency is increased;

7) When P _sc (t)＜-P _sc,max 、P _fc (t)＜P _fc,r 、LOH _hst (t)＞LOH _hst,min When the boundary frequency is increased;

8) When P _sc (t)＜0、SOC _sc (t)＜SOC _sc,max 、P _fc (t)＜P _fc,r 、LOH _hst (t)＞LOH _hst,min When the boundary frequency is increased;

P _sc (t)、P _el (t)、P _fc (t) represents the actual operating power, SOC of the super capacitor array, the electrolytic cell and the fuel cell respectively _sc (t) represents the state of charge of the supercapacitor array, LOH _hst (t) represents the hydrogen storage level of the hydrogen storage tank, P _sc,max Representing the maximum charging power of the super capacitor array, -P _sc,max Represents the maximum discharge power of the super capacitor array, P _el,r And P _fc,r Respectively represents rated power and SOC of an electrolytic cell and a fuel cell _sc,max And SOC (System on chip) _sc,min Respectively represent the upper limit and the lower limit of the charge state of the super capacitor, LOH _hst,max And LOH (Low-Density parity) _hst,min Indicating the upper limit and the lower limit of the hydrogen storage level of the hydrogen storage tank, respectively.

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