CN102368625A - Control method of battery energy storage system for restraining output power fluctuation of renewable energy source - Google Patents

Abstract

The invention relates to a control method of a battery energy storage system for inhibiting output power fluctuation of renewable energy sources. The control method is based on a low-pass filtering principle, the renewable energy output power value is filtered through a first-order Butterworth low-pass filter to obtain a renewable energy output power target value, and the difference between the renewable energy output power target value and the renewable energy output power measured value is compensated through charge and discharge control of the battery energy storage system, so that the purpose of restraining renewable energy output power fluctuation is achieved. The invention is based on the basic filtering principle, utilizes the renewable energy source to output power with good inhibition effect and adds

A feedback link is adopted to avoid the overcharge and the overdischarge of the battery, and innovation is carried out

When the feedback loop is in time, the output power of the energy storage system is indirectly changed by adjusting the size of the filtering time constant, so that the output power fluctuation of the renewable energy source is restrained, and meanwhile, the overcharge and the overdischarge of the battery are effectively avoidedThe stable operation of the battery energy storage system is maintained, and the service life of the battery is prolonged.

Description

The control method that suppresses the battery energy storage system of regenerative resource output-power fluctuation

Technical field

The present invention is a kind of control method that suppresses the battery energy storage system of regenerative resource output-power fluctuation; The energy storage control method of particularly a kind of state-of-charge based on battery energy storage system (SOC) and variable time constant filter belongs to distributed power generation energy supply technical field.

Background technology

Advantages such as renewable energy power generation is technological, and, distribution pollution-free, renewable with it like photovoltaic generation and wind power generation is wide have received increasing concern.Yet renewable energy power generation has the advantages that fluctuation is big, randomness is strong.Therefore, dispose the energy-storage system of a constant volume on the spot, can effectively suppress the fluctuation of renewable energy power generation power output, improve the ability that electrical network is admitted renewable energy power generation.

The control strategy of the energy-storage system of Chinese scholars proposition at present mainly contains two kinds:

1) one of which is basic filtering control method.The method is the basis with basic filtering principle; Adopt the low pass filter of deciding time constant filter that the power signal of regenerative resource is handled; To obtain its desired value, utilize the difference between control compensation regenerative resource power output desired value and the measured value that discharges and recharges of energy-storage system again.

2) it two is state-of-charge (SOC) feedback of battery energy storage system.The state-of-charge of battery energy storage system (SOC) is meant the real-time dump energy of battery.The method has been introduced the SOC feedback element on the basis of basic filtering control method, directly the output power value of energy-storage system is made amendment, so that the SOC value stabilization of battery is in certain scope.

The fluctuation that energy-storage system can the good restraining regenerative resource in first kind of control strategy; But filter time constant is single definite value; Regularly cause the super-charge super-discharge of battery energy storage system easily at the capacity one of energy-storage system; Thereby make battery out of service, cause the regenerative resource power output to occur than great fluctuation process; In second kind of control strategy; Introduced the SOC feedback element; When suppressing the regenerative resource output-power fluctuation, avoided the super-charge super-discharge of battery effectively, prolonged the useful life of battery; But the correction by the SOC feedback element obtains is directly revised the output power value of energy-storage system, has influenced the smooth effect of regenerative resource power output.

Summary of the invention

The objective of the invention is to consider the problems referred to above and provide a kind of when suppressing the regenerative resource output-power fluctuation; Avoided the super-charge super-discharge of battery effectively; Kept the stable operation of battery energy storage system, the control method of battery energy storage system of inhibition regenerative resource output-power fluctuation that has prolonged the useful life of battery.

Technical scheme of the present invention is: the control method that suppresses the battery energy storage system of regenerative resource output-power fluctuation; It is characterized in that this control method is based on lowpass filtering theory; Through the fertile low pass filter now of single order Bart the regenerative resource output power value is carried out filtering; Obtain regenerative resource power output desired value; Utilize the difference between control compensation regenerative resource power output desired value and the measured value that discharges and recharges of battery energy storage system, thereby reach the purpose that suppresses the regenerative resource output-power fluctuation.

The fertile time constant filter of low pass filter now of the single order Bart of above-mentioned employing; To select according to the spectrum analysis result of regenerative resource power output and the capacity of energy-storage system; At first regenerative resource typical case output power curve is carried out fast Fourier transform and obtain its frequency spectrum; According to battery energy storage system the frequency of the power fluctuation composition that will compensate, the designed filters time constant also will be taken all factors into consideration the capacity of battery energy storage system simultaneously.

Above-mentioned control method need be carried out stepping to state-of-charge (SOC) value of battery energy storage system, and when state-of-charge (SOC) value of battery energy storage system was being moved in the limits, energy-storage system adopts decided time constant filter control; When state-of-charge (SOC) value of battery energy storage system surpasses the operation limit value; Energy-storage system adopts variable time constant filter control; The state-of-charge of battery energy storage system (SOC) is meant the real-time dump energy of battery; Battery management system (BMS) is responsible for the information of battery is gathered and handled, and charging and discharging currents and Time Calculation through the battery real-time state-of-charge that goes out battery.Consult: battery management system (BMS) does not appear in previous contents, does battery management system (BMS) belong to battery energy storage system? (I think that BMS belongs to battery energy storage system---in ripple)

Above-mentioned control method is adjusted time constant filter according to the state-of-charge (SOC) of battery energy storage system; When suppressing the regenerative resource output-power fluctuation; Avoided the super-charge super-discharge of battery; Prolonged the life-span of battery, through the transfer function based on the energy-storage system power output of filtering principle is analyzed, the relation of energy-storage system output power value and time constant filter; According to the value of feedback of the state-of-charge (SOC) of battery energy storage system, through the adjustment time constant filter, change the output power value of energy-storage system indirectly, thereby state-of-charge (SOC) value stabilization that makes battery energy storage system is in certain scope.

Above-mentioned control method is the basis with the filtering principle, through the control that discharges and recharges of energy-storage system, and the fluctuation composition of a certain special frequency of compensation regenerative resource power output.

The time constant filter of the filter that above-mentioned control method adopted will be selected through renewable energy resources power output is carried out spectrum analysis under the condition that the energy-storage system capacity allows.

Above-mentioned control method is through state-of-charge (SOC) value of battery management system (BMS) battery energy storage system that provides; According to the size of energy-storage system output power value and the relation between the time constant filter; Adjust the size of time constant filter in real time, thereby state-of-charge (SOC) value stabilization that makes battery energy storage system is in certain scope.

Above-mentioned regenerative resource power output is P _rThe power output of battery energy storage system is P _BatThe power that injects power distribution network is P _LineBattery energy storage system power output reference value is P _{Bat_ref}

Can get according to principle of energy balance,

P _r+P _bat-P _line＝0 (1)

Wherein, P _BatFor just, represent the battery energy storage system discharge; P _BatFor negative, the charging of expression battery energy storage system;

Regenerative resource power output P _r,, obtain regenerative resource power output reference value P through the fertile low pass filter now of single order Bart _{R_ref}, itself and P _rSubtract each other the power output reference value P that obtains energy-storage system _{Bat_ref}, P _{Bat_ref}For just representing energy storage system discharges, be the charging of negative indication energy-storage system.The SOC value of battery that the energy storage controller is uploaded through BMS changes the size of time constant filter according to the method for adjustment of variable time constant filter, thereby the SOC value stabilization that makes battery is in certain scope;

Wherein, the fertile low pass filter now of single order Bart is shown below:

$H\left(s\right)=\frac{1}{1+\mathrm{sT}}---\left(2\right)$

Wherein, s is a differential operator; T is a time constant filter;

The fertile amplitude-frequency function of low pass filter now of single order Bart is the function of a monotone decreasing, equals at 0 o'clock in frequency, gets maximum 1; Frequency equals cut-off frequency w _cThe time, amplitude is 0.707;

The relation of each variable is following in the filtering control method:

$P_{r\_\mathrm{ref}}\left(s\right)=\frac{1}{1+\mathrm{sT}}\·P_r\left(s\right)---\left(3\right)$

$P_{\mathrm{bat}\_\mathrm{ref}}\left(s\right)=P_{r\_\mathrm{ref}}\left(s\right)-P_r\left(s\right)=-\frac{\mathrm{<figure-callout\; id="1"\; label="sT"\; filenames="111010104522.png,111010104540.png"\; state="\{\{state\}\}">sT</figure-callout>}}{1+\mathrm{sT}}\&CenterDot;P_r\left(s\right)---\left(4\right)$

S in (3) formula is represented with

, and can get after the difference:

$P_{r\_\mathrm{ref}}\left(t\right)=\frac{T_d}{T}[P_r\left(t\right)-P_{r\_\mathrm{ref}}(t-1)]+P_{r\_\mathrm{ref}}(t-1)---\left(5\right)$

By (4) Shi Kede,

P _{bat_ref}(t+1)＝P _{r_ref}(t)-P _r(t) (6)

Wherein, T _dBe computing cycle, P _{R_ref}(t-1) be the renewable energy power generation power P _{R_ref}(t) reference value in a last moment can be known by formula (6), in real system, calculates cycle T _dConfirm, so the reference signal P of next moment battery power output _{Bat_ref}(t+1) only with the renewable energy power generation power P of current time _r(t), the reference value Pr of previous moment renewable energy power generation power _{_ ref}(t-1) relevant with time constant filter T;

The state-of-charge SOC of battery is meant the battery current dump energy, and in the actual engineering, because cell memory capacity and operating voltage are lower, therefore big capacity energy-storage system all is made up of a plurality of battery pack connection in series-parallel; Battery management system (BMS) estimates the SOC value of each battery pack, and then through relatively obtaining the SOC value of whole energy-storage system;

On the basis of basic filtering control method, added the SOC FEEDBACK CONTROL, when the SOC value was in the limit value scope, energy-storage system adopted predefined time constant filter value to control; When the SOC value surpasses limit value,, little by little change the power output of battery, thereby the SOC value stabilization that makes battery has avoided effectively filling deeply deeply of battery to put in restricted portion through changing the size of time constant filter.

Battery SOC can carry out stepping according to its limit value, and SOC is divided into working range [SOC _Min, SOC _Max], adjusting range [SOC _Min, SOC _Low] U [SOC _High, SOC _Max], normal range (NR) (SOC _Low, SOC _High) and forbidden range with [0, SOC _Min) U (SOC _Max, 1].0≤SOC wherein _Min＜SOC _Low＜SOC _High＜SOC _Max≤1, as shown in Figure 5.SOC _MaxWith SOC _MinBe respectively the battery SOC bound, the SOC scope mustn't surpass [SOC when promptly battery operated _Min, SOC _Max], when SOC value of battery equals SOC _MaxThe time, the restriction charging of energy storage inverter only allows discharge, when SOC value of battery smaller or equal to SOC _MinThe time, energy storage inverter restriction discharge only allows charging.SOC _MaxWith SOC _MinThe purpose that is provided with sharply descends because of super-charge super-discharge causes the life-span for avoiding battery, general SOC _MaxGet 1, SOC _MinGet 0.3; SOC _HighWith SOC _LowThe bound of SOC value when being respectively the battery operate as normal, the purpose of its setting are to keep certain operation to regulate nargin, when SOC at (SOC _Low, SOC _High) in the scope during operation, time constant filter is constant, battery normally moves.When SOC at [SOC _Min, SOC _Low] U [SOC _High, SOC _Max] in the scope during operation, time constant filter begins to change, so that avoid or delay SOC to SOC _MinOr SOC _MaxApproach.SOC bound nargin is desirable 10%, i.e. SOC _Low=SOC _Min+ 0.1, SOC _High=SOC _Max-0.1.

The modification method of time constant filter mainly is SOC value and the regenerative resource fluctuation size present according to battery; Relation based on time constant filter and energy storage power output; Optimize and choose the time constant filter rate of change; Time constant filter to original is revised, thereby avoids or delay SOC to SOC _MinOr SOC _MaxApproach,, and prolong its life-span so that can guarantee the compensation effect that battery continues.Wherein, T _dBe control cycle; T _(t)Time constant filter for current time; T _(t+1)Be next time constant filter constantly; T _Min, T _MaxBound for time constant filter; C is the rate of change of time constant filter.C and T _dProduct be the correction of time constant filter, be shown below:

ΔT＝C·T _d (7)

Generally speaking, time constant filter is big more, and the required power of battery, capacity are many more.So when SOC operates in adjusting range [SOC _Min, SOC _Low] U [SOC _High, SOC _Max] time, its time constant filter should reduce, and when SOC approached its bound more, its time constant filter also should approach its lower limit T more _MinThereby, avoid or delay SOC to SOC _MaxOr SOC _MinApproach,, and prolong its life-span so that can guarantee the compensation effect that battery continues.

Variable time constant filter control method process is following:

The first step is gathered the SOC value that battery BMS system provides;

In second step, judge the SOC value, if SOC is greater than SOC _Max, energy storage inverter restriction charging only allows discharge, and jumped to for the 4th step; Otherwise, carry out next step;

The 3rd step is if SOC is less than SOC _Min, energy storage inverter restriction discharge only allows charging, carries out next step;

The 4th step is if SOC is less than SOC _HighAnd greater than SOC _Low, then battery forwarded for the 5th step to the fix time constant control of initial time constant filter;

If SOC is greater than SOC _High, then judge P _BatWhether greater than 0, if P _BatGreater than 0, then, if P _BatLess than 0, then, forwarded for the 5th step to;

If SOC is less than SOC _Low, then judge P _BatWhether greater than 0, if P _BatGreater than 0, then, if P _BatLess than 0, then, forwarded for the 5th step to;

In the 5th step, calculate current time renewable energy power generation power through filtered value P by formula (5) _{R_ref}(t), carry out next step;

In the 6th step, calculate next reference value P of electric power generation cell constantly by formula (6) _{Bat_ref}(t), and control command is issued to the energy storage inverter, returns the first step.

The present invention considers the regenerative resource power output because of receiving the influence of natural cause, has the big and strong characteristics of randomness of fluctuation, influences the stable operation of power distribution network.For suppressing the fluctuation of regenerative resource power output, the present invention is based on basic filtering principle, utilize the regenerative resource power output to suppress effective and adding SOC feedback element; Avoid the super-charge super-discharge of battery, and innovate, when adding the SOC feedback element; Through regulating the size of time constant filter; Change the power output of energy-storage system indirectly, thereby when suppressing the regenerative resource output-power fluctuation, avoided the super-charge super-discharge of battery effectively; Keep the stable operation of battery energy storage system, prolonged the useful life of battery.The present invention is a kind of energy storage control method based on real-time state-of-charge of battery and variable time constant, is a kind of control method of battery energy storage system of convenient and practical inhibition regenerative resource output-power fluctuation.

Description of drawings

Fig. 1 is the structure chart of regenerative resource of the present invention and energy-storage system;

Fig. 2 is the fertile low pass filter Bode diagram now of Bart of the present invention;

Fig. 3 is an energy-storage system power output transfer function Bode diagram sketch map of the present invention;

Fig. 4 is a battery SOC limit value sketch map of the present invention;

Fig. 5 is the variable time constant filter control method of a present invention structure chart;

Fig. 6 time constant filter method of adjustment control block diagram;

Fig. 7 is the variable time constant filter control flow chart of the present invention.

Embodiment

Embodiment:

Below according to Figure of description, to the further detailed presentations of technical scheme of the present invention.

Battery energy storage system and the renewable energy system structure chart that is incorporated into the power networks is as shown in Figure 1.Regenerative resource is connected to power distribution network through its energy converter, and battery energy storage system is connected to the ac bus place that regenerative resource is incorporated into the power networks through its two-way inverter.The energy storage controller is through gathering the power output signal of regenerative resource, according to the power output reference value that calculates energy-storage system based on the variable time constant filter control method of battery SOC, the fluctuation of regenerative resource power output suppressed.Arrow is represented energy Flow direction, P among the figure _rBe the regenerative resource power output; P _BatPower output for battery energy storage system; P _LineFor injecting the power of power distribution network; P _{Bat_ref}Be battery energy storage system power output reference value.

Can get according to principle of energy balance,

P _r+P _bat-P _line＝0 (1)

Wherein, P _BatFor just, represent the battery energy storage system discharge; P _BatFor negative, the charging of expression battery energy storage system.

When being meant energy-storage system the fluctuation composition of a certain frequency range suppresses in to the regenerative resource power output based on the variable time constant filter energy storage control method of battery SOC; Size according to SOC value of battery is revised time constant filter; So that the SOC value all-the-time stable of battery is avoided the super-charge super-discharge of battery in certain scope., its structure chart is as shown in Figure 2.Regenerative resource power output P _r,, obtain regenerative resource power output reference value P through the fertile low pass filter now of single order Bart _{R_ref}, itself and P _rSubtract each other the power output reference value P that obtains energy-storage system _{Bat_ref}, P _{Bat_ref}For just representing energy storage system discharges, be the charging of negative indication energy-storage system.The SOC value of battery that the energy storage controller is uploaded through BMS changes the size of time constant filter according to the method for adjustment of variable time constant filter, thereby the SOC value stabilization that makes battery is in certain scope.

Wherein, the fertile low pass filter now of single order Bart is shown below:

$H\left(s\right)=\frac{1}{1+\mathrm{sT}}---\left(2\right)$

Wherein, s is a differential operator; T is a time constant filter.Its amplitude-versus-frequency curve is as shown in Figure 3.

Can know that by Fig. 3 the fertile amplitude-frequency function of low pass filter now of single order Bart is the function of a monotone decreasing, equals at 0 o'clock in frequency, gets maximum 1; Frequency equals cut-off frequency w _cThe time, amplitude is 0.707.

The relation of each variable is following in the filtering control method:

$P_{r\_\mathrm{ref}}\left(s\right)=\frac{1}{1+\mathrm{sT}}\&CenterDot;P_r\left(s\right)---\left(3\right)$

$P_{\mathrm{bat}\_\mathrm{ref}}\left(s\right)=P_{r\_\mathrm{ref}}\left(s\right)-P_r\left(s\right)=-\frac{\mathrm{<figure-callout\; id="1"\; label="sT"\; filenames="111010104522.png,111010104540.png"\; state="\{\{state\}\}">sT</figure-callout>}}{1+\mathrm{sT}}\&CenterDot;P_r\left(s\right)---\left(4\right)$

The baud sketch map of battery energy storage system power output transfer function is as shown in Figure 4.

T is a time constant filter among Fig. 4, and w is the pairing frequency of time constant filter.Can be found out by Fig. 4: for time constant filter is T ₁Curve, the energy-storage system power output pass letter for frequency greater than w ₁Its power output amplitude of wave component be 1, promptly in theory energy-storage system can compensating frequency greater than w ₁All wave components; T among the figure ₁＞T ₂＞T ₃, w ₁＜w ₂＜w ₃, promptly the time constant is big more, and its corresponding frequency is just more little, and the frequency range that energy-storage system can compensate is just big more, and the output power value of energy-storage system is also just big more.

S in (3) formula is represented with

, and can get after the difference:

$P_{r\_\mathrm{ref}}\left(t\right)=\frac{T_d}{T}[P_r\left(t\right)-P_{r\_\mathrm{ref}}(t-1)]+P_{r\_\mathrm{ref}}(t-1)---\left(5\right)$

By (4) Shi Kede,

P _{bat_ref}(t+1)＝P _{r_ref}(t)-P _r(t) (6)

Wherein, T _dBe computing cycle, P _{R_ref}(t-1) be the renewable energy power generation power P _{R_ref}(t) reference value in a last moment.Can know by formula (6), in real system, calculate cycle T _dConfirm, so the reference signal P of next moment battery power output _{Bat_ref}(t+1) only with the renewable energy power generation power P of current time _r(t), the reference value P of previous moment renewable energy power generation power _{R_ref}(t-1) relevant with time constant filter T.

The state-of-charge SOC of battery is meant the battery current dump energy.In the actual engineering, because cell memory capacity and operating voltage are lower, therefore big capacity energy-storage system all is made up of a plurality of battery pack connection in series-parallel.Battery management system (BMS) estimates the SOC value of each battery pack, and then through relatively obtaining the SOC value of whole energy-storage system.

The present invention has added the SOC FEEDBACK CONTROL on the basis of basic filtering control method, when the SOC value was in the limit value scope, energy-storage system adopted predefined time constant filter value to control; When the SOC value surpasses limit value,, little by little change the power output of battery, thereby the SOC value stabilization that makes battery has avoided effectively filling deeply deeply of battery to put in restricted portion through changing the size of time constant filter.

The stepping of battery SOC limit value is as shown in Figure 5.SOC _HighWith SOC _LowBe the bound of battery operate as normal SOC value when just time constant filter is constant, when SOC surpassed these two limit values, time constant filter began to change; SOC _MaxWith SOC _MinThe maximin of SOC when battery operated is when SOC value of battery equals SOC _MaxThe time, the restriction charging of energy storage inverter only allows discharge, when SOC value of battery less than SOC _MinThe time, energy storage inverter restriction discharge only allows charging.

The modification method of time constant filter is as shown in Figure 6.Wherein, T _dBe control cycle; T _(t)Time constant filter for current time; T _(t+1)Be next time constant filter constantly; T _Min, T _MaxBound for time constant filter; C is the rate of change of time constant filter.C and T _dProduct be the correction of time constant filter, be shown below:

ΔT＝C·T _d (7)

The flow chart of variable time constant filter control method is as shown in Figure 7.

The first step is gathered the SOC value that battery BMS system provides;

In second step, judge the SOC value, if SOC is greater than SOC _Max, energy storage inverter restriction charging only allows discharge, and jumped to for the 4th step; Otherwise, carry out next step;

The 3rd step is if SOC is less than SOC _Min, energy storage inverter restriction discharge only allows charging, carries out next step;

The 4th step is if SOC is less than SOC _HighAnd greater than SOC _Low, then battery forwarded for the 5th step to the fix time constant control of initial time constant filter;

If SOC is greater than SOC _High, then judge P _BatWhether greater than 0, if P _BatGreater than 0, then, if P _BatLess than 0, then, forwarded for the 5th step to;

If SOC is less than SOC _Low, then judge P _BatWhether greater than 0, if P _BatGreater than 0, then, if P _BatLess than 0, then, forwarded for the 5th step to;

In the 5th step, calculate current time renewable energy power generation power through filtered value P by formula (5) _{R_ref}(t), carry out next step;

In the 6th step, calculate next reference value P of electric power generation cell constantly by formula (6) _{Bat_ref}(t), and control command is issued to the energy storage inverter, returns the first step.

The present invention is the control method of the battery energy storage system of inhibition regenerative resource output-power fluctuation, and this invention belongs to distributed power generation energy supply technical field.After energy-storage system adopts control method proposed by the invention; Can suppress the fluctuation of regenerative resource power output effectively; And the state-of-charge that keeps battery be the SOC value stabilization in certain scope, avoided the super-charge super-discharge of battery, prolonged the useful life of battery.

Claims (8)

1. control method that suppresses the battery energy storage system of regenerative resource output-power fluctuation; It is characterized in that this control method is based on lowpass filtering theory; Through the fertile low pass filter now of single order Bart the regenerative resource output power value is carried out filtering; Obtain regenerative resource power output desired value, utilize the difference between control compensation regenerative resource power output desired value and the measured value that discharges and recharges of battery energy storage system, thereby reach the purpose that suppresses the regenerative resource output-power fluctuation.

2. the control method of the battery energy storage system of inhibition regenerative resource output-power fluctuation according to claim 1; The fertile time constant filter of low pass filter now of single order Bart that it is characterized in that above-mentioned employing; To select according to the spectrum analysis result of regenerative resource power output and the capacity of energy-storage system; At first regenerative resource typical case output power curve is carried out fast Fourier transform and obtain its frequency spectrum; According to battery energy storage system the frequency of the power fluctuation composition that will compensate, the designed filters time constant also will be taken all factors into consideration the capacity of battery energy storage system simultaneously.

3. the control method of the battery energy storage system of inhibition regenerative resource output-power fluctuation according to claim 1; It is characterized in that above-mentioned control method need carry out stepping to state-of-charge (SOC) value of battery energy storage system; When state-of-charge (SOC) value of battery energy storage system was being moved in the limits, energy-storage system adopts decided time constant filter control; When state-of-charge (SOC) value of battery energy storage system surpasses the operation limit value; Energy-storage system adopts variable time constant filter control; The state-of-charge of battery energy storage system (SOC) is meant the real-time dump energy of battery; Battery management system (BMS) is responsible for the information of battery is gathered and handled, and charging and discharging currents and Time Calculation through the battery real-time state-of-charge that goes out battery.

4. the control method of the battery energy storage system of inhibition regenerative resource output-power fluctuation according to claim 1; It is characterized in that above-mentioned control method adjusts time constant filter according to the state-of-charge (SOC) of battery energy storage system; When suppressing the regenerative resource output-power fluctuation; Avoided the super-charge super-discharge of battery; Prolonged the life-span of battery, through the transfer function based on the energy-storage system power output of filtering principle is analyzed, the relation of energy-storage system output power value and time constant filter; According to the value of feedback of the state-of-charge (SOC) of battery energy storage system, through the adjustment time constant filter, change the output power value of energy-storage system indirectly, thereby state-of-charge (SOC) value stabilization that makes battery energy storage system is in certain scope.

5. the control method of the battery energy storage system of inhibition regenerative resource output-power fluctuation according to claim 1; It is characterized in that above-mentioned control method is the basis with the filtering principle; Through the control that discharges and recharges of energy-storage system, the fluctuation composition of a certain special frequency of compensation regenerative resource power output.

6. the control method of the battery energy storage system of inhibition regenerative resource output-power fluctuation according to claim 1; The time constant filter that it is characterized in that the filter that above-mentioned control method adopts; To under the condition that the energy-storage system capacity allows,, renewable energy resources power output select through being carried out spectrum analysis.

7. the control method of the battery energy storage system of inhibition regenerative resource output-power fluctuation according to claim 1; It is characterized in that state-of-charge (SOC) value of above-mentioned control method through battery management system (BMS) battery energy storage system that provides; According to the size of energy-storage system output power value and the relation between the time constant filter; Adjust the size of time constant filter in real time, thereby state-of-charge (SOC) value stabilization that makes battery energy storage system is in certain scope.

8. according to the control method of the battery energy storage system of each described inhibition regenerative resource output-power fluctuation of claim 1 to 7, it is characterized in that above-mentioned regenerative resource power output is P _rThe power output of battery energy storage system is P _BatThe power that injects power distribution network is P _LineBattery energy storage system power output reference value is P _{Bat_ref}

Get according to principle of energy balance,

P _r+P _bat-P _line＝0 (1)

Wherein, P _BatFor just, represent the battery energy storage system discharge; P _BatFor negative, the charging of expression battery energy storage system;

Regenerative resource power output P _r,, obtain regenerative resource power output reference value P through the fertile low pass filter now of single order Bart _{R_ref}, itself and P _rSubtract each other the power output reference value P that obtains energy-storage system _{Bat_ref}, P _{Bat_ref}For just representing energy storage system discharges, be the charging of negative indication energy-storage system; The SOC value of battery that the energy storage controller is uploaded through BMS changes the size of time constant filter according to the method for adjustment of variable time constant filter, thereby the SOC value stabilization that makes battery is in certain scope;

Wherein, the fertile low pass filter now of single order Bart is shown below:

$H\left(s\right)=\frac{1}{1+\mathrm{sT}}---\left(2\right)$

Wherein, s is a differential operator; T is a time constant filter;

The fertile amplitude-frequency function of low pass filter now of single order Bart is the function of a monotone decreasing, equals at 0 o'clock in frequency, gets maximum 1; Frequency equals cut-off frequency w _cThe time, amplitude is 0.707;

The relation of each variable is following in the filtering control method:

$P_{r\_\mathrm{ref}}\left(s\right)=\frac{1}{1+\mathrm{sT}}\&CenterDot;P_r\left(s\right)---\left(3\right)$

$P_{\mathrm{bat}\_\mathrm{ref}}\left(s\right)=P_{r\_\mathrm{ref}}\left(s\right)-P_r\left(s\right)=-\frac{\mathrm{sT}}{1+\mathrm{sT}}\&CenterDot;P_r\left(s\right)---\left(4\right)$

S in (3) formula is represented with

, and after the difference:

$P_{r\_\mathrm{ref}}\left(t\right)=\frac{T_d}{T}[P_r\left(t\right)-P_{r\_\mathrm{ref}}(t-1)]+P_{r\_\mathrm{ref}}(t-1)---\left(5\right)$

Get by (4) formula,

P _{bat_ref}(t+1)＝P _{r_ref}(t)-P _r(t) (6)

Wherein, T _dBe computing cycle, P _{R_ref}(t-1) be the renewable energy power generation power P _{R_ref}(t) reference value in a last moment is known by formula (6), in real system, calculates cycle T _dConfirm, so the reference signal P of next moment battery power output _{Bat_ref}(t+1) only with the renewable energy power generation power P of current time _r(t), the reference value P of previous moment renewable energy power generation power _{R_ref}(t-1) relevant with time constant filter T;

The state-of-charge SOC of battery is meant the battery current dump energy, and in the actual engineering, because cell memory capacity and operating voltage are lower, therefore big capacity energy-storage system all is made up of a plurality of battery pack connection in series-parallel; Battery management system (BMS) estimates the SOC value of each battery pack, and then through relatively obtaining the SOC value of whole energy-storage system;

On the basis of basic filtering control method, added the SOC FEEDBACK CONTROL, when the SOC value was in the limit value scope, energy-storage system adopted predefined time constant filter value to control; When the SOC value surpasses limit value,, little by little change the power output of battery, thereby the SOC value stabilization that makes battery has avoided effectively filling deeply deeply of battery to put in restricted portion through changing the size of time constant filter;

Battery SOC carries out stepping according to its limit value, and SOC is divided into working range [SOC _Min, SOC _Max], adjusting range [SOC _Min, SOC _Low] U [SOC _High, SOC _Max], normal range (NR) (SOC _Low, SOC _High) and forbidden range with [0, SOC _Min) U (SOC _Max, 1]; 0≤SOC wherein _Min＜SOC _Low＜SOC _High＜SOC _Max≤1, SOC _MaxWith SOC _MinBe respectively the battery SOC bound, the SOC scope mustn't surpass [SOC when promptly battery operated _Min, SOC _Max], when SOC value of battery equals SOC _MaxThe time, the restriction charging of energy storage inverter only allows discharge, when SOC value of battery smaller or equal to SOC _MinThe time, energy storage inverter restriction discharge only allows charging; SOC _MaxWith SOC _MinThe purpose that is provided with sharply descends because of super-charge super-discharge causes the life-span for avoiding battery, general SOC _MaxGet 1, SOC _MinGet 0.3; SOC _HighWith SOC _LowThe bound of SOC value when being respectively the battery operate as normal, the purpose of its setting are to keep certain operation to regulate nargin, when SOC at (SOC _Low, SOC _High) in the scope during operation, time constant filter is constant, battery normally moves; When SOC at [SOC _Min, SOC _Low] U [SOC _High, SOC _Max] in the scope during operation, time constant filter begins to change, so that avoid or delay SOC to SOC _MinOr SOC _MaxApproach; SOC bound nargin gets 10%, i.e. SOC _Low=SOC _Min+ 0.1, SOC _High=SOC _Max-0.1;

The modification method of time constant filter mainly is SOC value and the regenerative resource fluctuation size present according to battery; Relation based on time constant filter and energy storage power output; Optimize and choose the time constant filter rate of change; Its time constant filter is repaired, thereby avoided or delay SOC to SOC _MinOr SOC _MaxApproach,, and prolong its life-span so that can guarantee the compensation effect that battery continues; Wherein, T _dBe control cycle; T _(t)Time constant filter for current time; T _(t+1)Be next time constant filter constantly; T _Min, T _MaxBound for time constant filter; C is the rate of change of time constant filter; C and T _dProduct be the correction of time constant filter, be shown below:

ΔT＝C·T _d (7)

Generally speaking, time constant filter is big more, and the required power of battery, capacity are many more; So when SOC operates in adjusting range [SOC _Min, SOC _Low] U [SOC _High, SOC _Max] time, its time constant filter should reduce, and when SOC approached its bound more, its time constant filter also should approach its lower limit T more _MinThereby, avoid or delay SOC to SOC _MinOr SOC _MaxApproach,, and prolong its life-span so that can guarantee the compensation effect that battery continues;

Variable time constant filter control method process is following:

The first step is gathered the SOC value that battery BMS system provides;

In second step, judge the SOC value, if SOC is greater than SOC _{Max x}, energy storage inverter restriction charging only allows discharge, and jumped to for the 4th step; Otherwise, carry out next step;

The 3rd step is if SOC is less than SOC _Min, energy storage inverter restriction discharge only allows charging, carries out next step;

The 4th step is if SOC is less than SOC _HighAnd greater than SOC _Low, then battery forwarded for the 5th step to the fix time constant control of initial time constant filter;

If SOC is greater than SOC _High, then judge P _BatWhether greater than 0, if P _BatGreater than 0, then, if P _BatLess than 0, then, forwarded for the 5th step to;

If SOC is less than SOC _Low, then judge P _BatWhether greater than 0, if P _BatGreater than 0, then, if P _BatLess than 0, then, forwarded for the 5th step to;

In the 5th step, calculate current time renewable energy power generation power through filtered value P by formula (5) _{R_ref}(t), carry out next step;

In the 6th step, calculate next reference value P of electric power generation cell constantly by formula (6) _{Bat_ref}(t), and control command is issued to the energy storage inverter, returns the first step.

Images