Cooperative control method for stabilizing wind and light fluctuation of electrolytic cell-storage battery

Abstract

The invention relates to a cooperative control method for stabilizing wind-light fluctuation through an electrolytic cell-storage battery, and belongs to the technical field of wind-light-hydrogen storage combined power generation system control. According to the sequential relation between the fluctuation characteristics of wind power and photovoltaic and the dynamic characteristics of the electrolytic cell-storage battery, in the upward fluctuation stage, an alkaline electrolytic cell is preferentially used for increasing power; secondly, increasing power by using a PEM electrolytic bath and a storage battery; in the downward fluctuation stage, the alkaline electrolytic bath is preferentially used for reducing power, and then the PEM electrolytic bath and the storage battery are used for reducing power / discharging; meanwhile, on the basis of the dynamic characteristic constraint of the alkaline electrolytic cell, the power of the PEM electrolytic cell and the storage battery is adjusted in real time according to the state of charge (SOC) of the storage battery, overcharge and overdischarge of the storage battery can be effectively avoided, wind and light are effectively absorbed, and fluctuation of the wind and light is stabilized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of control of wind-solar-hydrogen storage combined power generation system, in particular to a method for electrolytic cell-battery coordinated control for smoothing wind-solar fluctuation. BACKGROUND

[0002] Wind power and photovoltaic new energy generation has become a hot spot in recent years due to its characteristics of cleanliness, high efficiency, and no pollution. However, wind power and photovoltaic new energy generation has strong volatility, intermittency and randomness, which has increasingly serious adverse effects on system reliable operation and economic operation.

[0003] At present, in order to smooth fluctuation, power type storage and energy type storage are combined to form hybrid storage to smooth wind power and photovoltaic fluctuation. Wind power and photovoltaic new energy generation can convert part of the electric energy into hydrogen energy by electrolyzing water to produce hydrogen, which can realize wind power fluctuation smoothing and long-term energy storage, providing a new idea for solving the problem that traditional storage methods cannot realize long-term energy storage.

[0004] At present, there are a few studies on the combination of electrolytic cell and super capacitor storage to smooth wind power and photovoltaic fluctuation. Electrolytic cell can be divided into alkaline electrolytic cell (energy type) and PEM electrolytic cell (power type), and the combination of the two types of electrolytic cell and storage to absorb wind power and photovoltaic and smooth their fluctuation is a current research hotspot, but the current research has limited effect on smoothing wind power and photovoltaic fluctuation. SUMMARY

[0005] In order to overcome the problems in the background art, the application provides a method for electrolytic cell-battery coordinated control for smoothing wind-solar fluctuation, which can effectively avoid overcharging and overdischarging of the battery and effectively absorb wind-solar and smooth their fluctuation.

[0006] To achieve the above purpose, the application is realized by the following technical scheme:

[0007] The electrolytic cell-battery coordinated control method for smoothing wind-solar fluctuation comprises:

[0008] Step 1, according to the time sequence relationship between the fluctuation characteristics of wind power and photovoltaic and the dynamic characteristics of electrolytic cell-battery, determine the upward fluctuation and downward fluctuation stages of wind-solar fluctuation in a dispatching period;

[0009] Step 2,

[0010] In the upward fluctuation stage, the alkaline electrolytic cell is preferentially used to increase power, and then the PEM electrolytic cell and the battery are used to increase power;

[0011] In the downward fluctuation stage, the alkaline electrolytic cell is preferentially used to decrease power, and then the PEM electrolytic cell and the battery are used to decrease power / discharge.

[0012] Step 3, based on the dynamic characteristics of the alkaline electrolyzer, the power of the battery and the PEM electrolyzer is adjusted according to the state of charge SOC of the battery.

[0013] Further, the output power of the fan is P wind , the output power of the photovoltaic is P pv , and t is the reference sampling time 1s.

[0014] If the wind and light fluctuation is in the upward fluctuation stage, P total (T)≥P total (T-1), then the upward power P AEM (T) required by the alkaline electrolyzer to absorb the wind and light fluctuation in the time interval ΔT at time T is calculated as:

[0015] ΔP total (T)=P total (T)-P total (T-1)

[0016] P AEM (T)=min{ΔP total (T),R AEM ΔT}

[0017] In the formula, R AEM is the ramp rate of the alkaline electrolyzer; P total is the combined power of wind and light; and T is the smoothing time.

[0018] Wherein, P total =P pv +P wind .

[0019] T=kt,k=1,2,3,...,n, and t is the reference sampling time 1s.

[0020] Further, if the power difference ΔP total (T) of the combined power of wind and light in the time interval ΔT is less than the amount of power of the alkaline electrolyzer, then the alkaline electrolyzer performs the power-up, and the battery and the PEM electrolyzer do not act; otherwise, the PEM electrolyzer and the battery need to perform power-up; the total power P res (T) to be upgraded of the PEM electrolyzer and the battery is:

[0021] P res (T)=ΔP total (T)-P AEM (T)

[0022] Further, the dynamic characteristics of the battery and the PEM electrolyzer at time T are determined to allocate power, first, the maximum available charging power of the battery at time T is determined according to the charging power characteristics of the battery For:

[0023]

[0024] In the formula, The maximum charging power of the battery, E is the remaining chargeable amount of the battery at time T max The maximum capacity of the battery;

[0025] Then, the maximum available charging power of the PEM electrolyzer at time T is determined according to the ramp-up characteristics of the PEM electrolyzer, that is:

[0026]

[0027] In the formula, P PEM_norm The rated power of the PEM electrolyzer, λ PEM The overload power ratio, R PEM The ramp-up rate.

[0028] Finally, the maximum wind and solar power that can be absorbed is determined according to the maximum available power of the battery and the PEM electrolyzer According to The battery and the PEM electrolyzer are allocated to the charging power according to the SOC state of the battery:

[0029]

[0030]

[0031] In the formula, And The charging power allocation coefficient of the battery and the PEM electrolyzer, and

[0032] The state of charge SOC of the battery at time T is:

[0033]

[0034] In the formula, η c The charging efficiency of the battery, E is the rated capacity of the battery.

[0035] Further, if the wind and solar fluctuations are in the downward fluctuation phase, P total (T) < P total (T-1) and P BS (T-1) ≥ 0, the alkaline electrolyzer is calculated to absorb the downward required power PAEM (T) is:

[0036] ΔP total (T) = P total (T-1) - P total (T)

[0037] P AEM (T) = min{ΔP total (T), D AEM ΔT}

[0038] wherein D AEM is the power reduction rate of the alkaline electrolyzer.

[0039] Further, if the power difference ΔP total (T) of the wind-solar combined power within the time interval ΔT is less than the power reduction amount of the alkaline electrolyzer, the alkaline electrolyzer is powered down, and the battery and the PEM electrolyzer are not powered down; otherwise, the PEM electrolyzer and the battery need to be powered down; the total power P res (T) to be reduced by the PEM electrolyzer and the battery is:

[0040] P res (T) = ΔP total (T) - P AEM (T).

[0041] Further, the difference between P res (T) at time T and the power reduction capability of the battery and the PEM electrolyzer is ΔP res (T), according to the dynamic characteristics of the battery, the maximum power reduction capability of the battery is the battery power P BS (T-1) at the last time, and the power reduction rate of the PEM electrolyzer is D PEM , the maximum power reduction capability of the PEM electrolyzer at time T is determined as: The maximum power reduction capability of the system is:

[0042]

[0043] If the power reduction distribution of the battery and the PEM electrolyzer is performed according to the SOC state of the battery:

[0044]

[0045] wherein, and are the charging power distribution coefficients of the battery and the PEM electrolyzer, and

[0046] If ​If the power of the battery and the PEM electrolyzer are both reduced to 0, the system cannot meet the reduced power, so the battery needs to be discharged to make up for the power. First, the discharge power characteristics of the battery are determined, and the discharge power of the battery at time T is:

[0047]

[0048] In the formula, is the maximum discharge power of the battery, is the remaining dischargeable amount of the battery at time T, E min is the minimum capacity of the battery; and

[0049] The state of charge SOC of the battery during discharge is:

[0050]

[0051] In the formula, η d is the discharge efficiency of the battery.

[0052] Further, the power distribution of the battery and the PEM electrolyzer is based on the state of charge SOC of the battery, and specifically,

[0053] When the total power P res (T) of the PEM electrolyzer and the battery to be increased or decreased is greater than 0, the PEM electrolyzer and the battery jointly consume, and the state of charge SOC of the battery is divided into three working conditions:

[0054] Working condition 1, when the state of charge SOC of the battery is in the range of SOC min ≤ SOC(T) ≤ SOC max , the PEM electrolyzer and the battery jointly consume; when the battery and the PEM electrolyzer need to increase power, the greater the SOC of the battery, the less the increase power allocated, and the more the PEM electrolyzer allocates; when the battery and the PEM electrolyzer need to decrease power, the greater the SOC of the battery, the greater the decrease power allocated, and the less the PEM electrolyzer allocates, which is expressed as,

[0055]

[0056] Working condition 2, when the state of charge (SOC) of the battery is in the range of SOC(T) < SOC min , the total power P res (T) is preferentially consumed by the battery, and if there is a surplus, the PEM electrolyzer is consumed;

[0057] Working condition 3, when the state of charge (SOC) of the battery is in the range of SOC(T) ≥ SOC max , the total power P res(T) by PEM electrolytic cell, battery stop charging

[0058] Advantages of the present application:

[0059] The present application according to the wind and light fluctuation in a scheduling cycle in the upward fluctuation and downward fluctuation stage: in the upward fluctuation stage, prefer to use the alkaline electrolytic cell to increase power, secondly use the PEM electrolytic cell and the battery to increase power; in the downward fluctuation stage, prefer to use the alkaline electrolytic cell to reduce power, secondly use the PEM electrolytic cell and the battery to reduce power / discharge; the present application takes the dynamic characteristics of the alkaline electrolytic cell as the basis for absorbing wind and light power, according to the dynamic characteristics of the PEM electrolytic cell and the battery combination mode to suppress wind and light fluctuation, more in line with the actual application, using control strategy to allocate power for the PEM electrolytic cell and the battery, which can effectively avoid overcharging and overdischarging of the battery, and effectively absorb wind and light and suppress its fluctuation. BRIEF DESCRIPTION OF DRAWINGS

[0060] Figure 1 is the control method flow chart of the present application. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical scheme and beneficial effects of the present application more clear, the technical scheme of the present application will be described in detail below, obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0062] In order to more clearly illustrate the present application, the following embodiments will be described in detail.

[0063] EMBODIMENT

[0064] According to the time sequence relationship between the fluctuation characteristics of wind power and photovoltaic power and the dynamic characteristics of electrolytic cell-battery, the upward fluctuation and downward fluctuation stage of wind and light fluctuation in a scheduling cycle is determined.

[0065] In the upward fluctuation stage, prefer to use the alkaline electrolytic cell to increase power, secondly use the PEM electrolytic cell and the battery to increase power;

[0066] In the downward fluctuation stage, prefer to use the alkaline electrolytic cell to reduce power, secondly use the PEM electrolytic cell and the battery to reduce power / discharge;

[0067] Based on the dynamic characteristics of the alkaline electrolytic cell, according to the state of charge SOC of the battery, the power of the PEM electrolytic cell and the battery is adjusted in real time, as follows:

[0068] Step 1, the output power of the fan is P wind , the output power of photovoltaic is Ppv Combined wind and solar power (P) total =P pv +P wind t is the baseline sampling time of 1 second. The smoothing time is T = kt, k = 1, 2, 3, ..., n.

[0069] Step 2, if P total (T)≥P total (T-1), then calculate the required uplift power P of the alkaline electrolyzer at time T to absorb the wind and solar fluctuations within the time interval ΔT. AEM (T) is:

[0070] ΔP total (T)=P total (T)-P total (T-1)

[0071] P AEM (T)=min{ΔP total (T),R AEM ΔT}

[0072] In the formula, R AEM This represents the ramp rate of the alkaline electrolytic cell.

[0073] Step 3, if the combined wind and solar power differs by ΔP within the time interval ΔT total If (T) is less than the power boosting capacity of the alkaline electrolyzer, then the alkaline electrolyzer will boost the power, and the battery and PEM electrolyzer will not operate; conversely, if (T) is greater than the alkaline electrolyzer, then both the PEM electrolyzer and the battery are needed to boost the power. The total power P to be boosted by the PEM electrolyzer and battery is... res (T) is:

[0074] P res (T)=ΔP total (T)-P AEM (T).

[0075] Step 4: Determine the dynamic characteristics of the battery and PEM electrolyzer at time T to allocate power. First, based on the battery's charging power characteristics, determine the maximum available charging power of the battery at time T. for:

[0076]

[0077] In the formula, Maximum charging power of the battery E represents the remaining rechargeable capacity of the battery at time T. max This is the maximum capacity of the battery.

[0078] Then, based on the ramp-up characteristics of the PEM electrolyzer, the maximum available charging power of the PEM electrolyzer at time T is determined as follows:

[0079]

[0080] In the formula, P PEM_norm The rated power of the PEM electrolyzer is λ, and the overload power ratio is λ. PEM The climbing rate is R PEM .

[0081] Finally, the maximum absorbable wind and solar power was determined based on the combined maximum available power of the storage battery and the PEM electrolyzer. Then according to Distribute boost power to the battery and PEM electrolyzer based on the battery's state of charge (SOC):

[0082]

[0083]

[0084] In the formula, and The charging power allocation coefficient for the storage battery and the PEM electrolyzer, and

[0085] The state of charge (SOC) of the battery at time T is:

[0086]

[0087] In the formula, η c E represents the charging efficiency of the battery, and E represents the rated capacity of the battery.

[0088] Step 5, if P total (T) < P total (T-1) and P BS If (T-1)≥0, then calculate the power reduction P required by the alkaline electrolyzer to absorb the downward fluctuations of wind and solar energy within the time interval ΔT at time T. AEM (T) is:

[0089] ΔP total (T)=P total (T-1)-P total (T)

[0090] P AEM (T)=min{ΔP total (T),D AEM ΔT}

[0091] In the formula, D AEM This refers to the power reduction rate of the alkaline electrolyzer.

[0092] Step 6, if the combined wind and solar power differs by ΔP within the time interval ΔT total(T) is less than the power reduction amount of the alkaline electrolyzer, the power is reduced by the alkaline electrolyzer, and the battery and the PEM electrolyzer are not in action; otherwise, the PEM electrolyzer and the battery need to reduce power. The total power P res (T) is:

[0093] P res (T) = ΔP total (T) - P AEM (T)

[0094] Step 7, determine P res (T) and the difference between the battery and the PEM electrolyzer is ΔP res (T), according to the dynamic characteristics of the battery, the maximum power reduction of the battery is the battery power at the last time P BS (T-1), the power reduction rate of the PEM electrolyzer is D PEM , determine the maximum available power reduction of the PEM electrolyzer at T The maximum power reduction of the system is which can be expressed as:

[0095]

[0096] If then the battery and the PEM electrolyzer are reduced according to the SOC state of the battery:

[0097]

[0098] In the formula, and are the charging power distribution coefficients of the battery and the PEM electrolyzer, and

[0099] If it means that the power of the battery and the PEM electrolyzer cannot be reduced to 0 to meet the system power reduction, so the battery needs to be discharged to make up for this part of the power. First, the discharge power characteristics of the battery, the discharge power of the battery at T is:

[0100]

[0101] In the formula, is the maximum discharge power of the battery, is the remaining dischargeable amount of the battery at T, E min is the minimum capacity of the battery.

[0102] The state of charge SOC of the battery during discharging is:

[0103]

[0104] In the formula, η d is the discharge efficiency of the battery.

[0105] The cooperative control method of power distribution of the battery and the PEM electrolyzer according to the state of charge (SOC) of the battery in steps 3 and 6 is described in detail as follows:

[0106] When the total power P res (T)≥0, it is jointly consumed by the PEM electrolyzer and the battery. According to the state of charge (SOC) of the battery, it can be divided into the following three working conditions:

[0107] Working condition 1: when the state of charge (SOC) of the battery is in the range of SOC min ≤SOC(T)≤SOC max , it is jointly consumed by the PEM electrolyzer and the battery. When the battery and the PEM electrolyzer need to increase power, the greater the SOC of the battery, the less the power increase distributed to the battery, and the more the power increase distributed to the PEM electrolyzer; when the battery and the PEM electrolyzer need to decrease power, the greater the SOC of the battery, the greater the power decrease distributed to the battery, and the less the power decrease distributed to the PEM electrolyzer, which can be expressed as:

[0108]

[0109] Working condition 2: when the state of charge (SOC) of the battery is in the range of SOC(T)<SOC min , the total power P res (T) is preferentially consumed by the battery, and if there is excess, it is consumed by the PEM electrolyzer.

[0110] Working condition 3: when the state of charge (SOC) of the battery is in the range of SOC(T)≥SOC max , the total power P res (T) is consumed by the PEM electrolyzer, and the battery stops charging.

[0111] The method of the present application can effectively avoid overcharging and overdischarging of the battery, and effectively consume wind and light and smooth their fluctuations.

[0112] Finally, it should be pointed out that the above preferred embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present application.

Claims

1. A collaborative control method for smoothing wind and solar energy fluctuations using an electrolyzer and a storage battery, characterized in that, Includes the following: Step 1: Based on the temporal relationship between the fluctuation characteristics of wind power and photovoltaic power and the dynamic characteristics of electrolyzer-battery, determine the upward and downward fluctuation phases of wind and solar power fluctuations within a scheduling cycle. Step 2, During the upward fluctuation phase, alkaline electrolyzers are used first to increase power, followed by PEM electrolyzers and batteries. During the downward fluctuation phase, alkaline electrolyzers are used first to reduce power, followed by PEM electrolyzers and batteries to reduce power / discharge. Step 3: Based on the dynamic characteristics constraints of the alkaline electrolyzer, the power of the PEM electrolyzer and the battery is adjusted in real time according to the state of charge (SOC) of the battery.

2. The collaborative control method according to claim 1, characterized in that, With the output power of the fan as P wind The output power of the photovoltaic is P pv t is the baseline sampling time of 1 second; If the landscape is fluctuating upwards, P total (T)≥P total (T-1), then calculate the required uplift power P of the alkaline electrolyzer at time T to absorb the wind and solar fluctuations within the time interval ΔT. AEM (T) is: ΔP total (T)=P total (T)-P total (T-1) P AEM (T)=min{ΔP total (T),R AEM ΔT} In the formula, R AEM P represents the ramp rate of the alkaline electrolyzer; total The combined wind and solar power output is represented by T, which is the smoothing time. Among them, P total =P pv +P wind ; T = kt, k = 1, 2, 3, ..., n, t is the reference sampling time 1 second.

3. The cooperative control method according to claim 2, characterized in that, If the combined wind and solar power output differs by ΔP within the time interval ΔT total If (T) is less than the power boosting capacity of the alkaline electrolyzer, then the alkaline electrolyzer will boost the power, and the battery and PEM electrolyzer will not operate; conversely, if (T) is greater than the alkaline electrolyzer, then the PEM electrolyzer and battery need to boost the power; the total power P to be boosted by the PEM electrolyzer and battery is... res (T) is: P res (T)=ΔP total (T)-P AEM (T)。 4. The collaborative control method according to claim 3, characterized in that, To allocate power based on the dynamic characteristics of the battery and PEM electrolyzer at time T, the maximum available charging power of the battery at time T is first determined according to its charging power characteristics. for: In the formula, Maximum charging power of the battery E represents the remaining rechargeable capacity of the battery at time T. max This is the maximum capacity of the battery; Then, based on the ramp-up characteristics of the PEM electrolyzer, the maximum available charging power of the PEM electrolyzer at time T is determined as follows: In the formula, P PEM_norm λ is the rated power of the PEM electrolyzer. PEM R is the overload power ratio. PEM The rate of ascent; Finally, the maximum absorbable wind and solar power was determined based on the combined maximum available power of the storage battery and the PEM electrolyzer. Then according to Distribute boost power to the battery and PEM electrolyzer based on the battery's state of charge (SOC): In the formula, and The charging power allocation coefficient for the storage battery and the PEM electrolyzer, and The state of charge (SOC) of the battery at time T is: In the formula, η c E represents the charging efficiency of the battery, and E represents the rated capacity of the battery.

5. The collaborative control method according to claim 1, characterized in that, If the landscape is fluctuating downwards, P total (T) < P total (T-1) and P BS If (T-1)≥0, then calculate the power reduction P required by the alkaline electrolyzer to absorb the downward fluctuations of wind and solar energy within the time interval ΔT at time T. AEM (T) is: ΔP total (T)=P total (T-1)-P total (T) P AEM (T)=min{ΔP total (T),D AEM ΔT} In the formula, D AEM This refers to the power reduction rate of the alkaline electrolyzer.

6. The cooperative control method according to claim 5, characterized in that, If the combined wind and solar power output differs by ΔP within the time interval ΔT total If (T) is less than the power reduction amount of the alkaline electrolyzer, then the alkaline electrolyzer will reduce the power, and the battery and PEM electrolyzer will not operate; otherwise, the PEM electrolyzer and battery will need to reduce the power. The total power P to be reduced by the PEM electrolyzer and battery is... res (T) is: P res (T)=ΔP total (T)-P AEM (T)。 7. The cooperative control method according to claim 6, characterized in that, Determine P at time T res The difference between (T) and the power reduction of the battery and PEM electrolyzer is ΔP. res (T), based on the dynamic characteristics of the battery, the maximum derating power of the battery is determined to be the battery power P at the previous moment. BS (T-1), the power reduction rate of the PEM electrolyzer is D. PEM Determine the maximum available power reduction of the PEM electrolyzer at time T. The maximum power reduction of the system It can be represented as: like Then, power reduction is allocated to the battery and PEM electrolyzer according to the battery's SOC state: In the formula, and The charging power allocation coefficient for the storage battery and the PEM electrolyzer, and like This indicates that reducing the power of both the battery and the PEM electrolyzer to zero is insufficient to meet the system's power reduction requirements; therefore, the battery needs to discharge to compensate for this power loss. First, considering the battery's discharge power characteristics, the discharge power of the battery at time T is determined as follows: In the formula, This is the maximum discharge power of the battery. E represents the remaining dischargeable capacity of the battery at time T. min This is the minimum capacity of the battery; The state of charge (SOC) of a battery during discharge is: In the formula, η d This refers to the discharge efficiency of the battery.

8. The cooperative control method according to claim 4 or 7, characterized in that, The power distribution between the battery and the PEM electrolyzer is based on the battery's state of charge (SOC). Specifically, When the total power P of the PEM electrolyzer and battery to be increased or decreased res (T)≥0, the energy is jointly absorbed by the PEM electrolyzer and the battery, and the operating conditions are divided into 3 types based on the battery's state of charge (SOC): Operating condition 1, when the battery's state of charge (SOC) ranges from 1 to 10. min ≤SOC(T)≤SOC max When the battery is in use, it is consumed by both the PEM electrolyzer and the battery. When the battery and PEM electrolyzer need to increase their power output, the higher the battery's SOC, the less power is allocated to the battery, and the more power is allocated to the PEM electrolyzer. When power reduction is required in both the battery and the PEM electrolyzer, the higher the battery's State of Charge (SOC), the greater the allocated power reduction, and the less power is allocated to the PEM electrolyzer. This is expressed as follows: Operating condition 2, when the state of charge (SOC) of the battery is less than SOC(T) < SOC min At that time, the total power P res (T) Priority will be given to the disposal of storage batteries. If there are any surpluses, they will be disposed of by PEM electrolysis cells. Operating condition 3, when the state of charge (SOC) of the battery is in the range of SOC(T) ≥ SOC max At that time, the total power P res (T) is absorbed by the PEM electrolytic cell, and the battery stops charging.

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