CN103683309A - Active power classified distribution method for hybrid energy storage system applied to micro-grid - Google Patents

Abstract

The invention discloses an active power classified distribution method for a hybrid energy storage system applied to a micro-grid. The active power classified distribution method is characterized in that the micro-grid hybrid energy storage system formed by a super-capacitor energy storage module, a storage battery energy storage module and an energy storage coordinating controller is arranged. The distributed method includes the following steps that 1, total active power of a hybrid energy storage target, a super capacitive SOC measured value and a storage battery SOC measured value are obtained; 2, first-level distribution is performed on the total active power of the hybrid energy storage target; 3, second-level distribution is performed based on the super-capacitor SOC measured value; 4, the second-level distribution is performed based on the storage battery SOC measured value; 5, distribution results are output to complete the active power classification and distribution. The active power classification and distribution method can effectively avoid over charging and over discharging of a super-capacitor and a storage battery, the number of times for circulation of the storage battery is reduced, service life of the super-capacitor and the storage battery is prolonged, and stability and performance indexes of the micro-grid are improved.

Description

A kind of meritorious classification distribution method that is applied to mixed energy storage system in micro-electrical network

Technical field

The present invention relates to the application of energy storage technology in micro-electrical network, be specifically related to a kind of meritorious classification distribution method that is applied to mixed energy storage system in micro-electrical network.

Background technology

A typical micro-electrical network is comprised of multiple distributed power generation unit, energy storage and load, and is responsible for the power generation dispatching in micro-electrical network by microgrid energy management system.Wherein, energy storage, the improvement of the quality of power supply and uninterrupted power supply have very important effect, is the key factor that maintains micro-power grid operation for the stable control of micro-electrical network.Single energy-storage system only has the specific character in mass property or fast response characteristic, cannot meet the demand of the micro-electrical network of high-performance, and the hybrid energy-storing that has mass property and fast response characteristic concurrently is significant to improving micro-electric network performance index.The energy storage technology that is applicable to micro-electrical network mainly contains the energy storage of battery class, ultracapacitor energy storage, flywheel energy storage and super conductive magnetic storage energy etc., wherein battery class energy storage (comprising lead acid accumulator, lithium iron phosphate storage battery, sodium-sulphur battery etc.) is energy type energy-storage travelling wave tube, has mass property; Then three is power-type energy-storage travelling wave tube, has the characteristic of quick response, and lithium iron phosphate storage battery and super capacitor rely on the advantages such as their reliabilities are high, technology maturation to become the first-selection that is applied to hybrid energy-storing in micro-electrical network.Be applied to choosing of mixed energy storage system control algolithm in micro-electrical network most important, control the useful life that improper meeting has a strong impact on micro-grid stability and hybrid accumulator.

At present, for the power distribution method of hybrid energy-storing, generally have following several:

The first is to adopt how stagnant ring to regulate control strategy, according to the output characteristic of super capacitor and storage battery, distribute the two power output, optimized storage battery output, the performance index of micro-electrical network have been improved, but, this control method does not consider that super capacitor and storage battery put power stage restriction under state overcharging or crossing, and overcharge or cross, puts state and can cause damage to super capacitor and storage battery, has reduced super capacitor and service lifetime of accumulator;

The second is the control strategy based on energy storage SOC, this method is to bear to greatest extent hybrid energy-storing gross power meeting super capacitor under super capacitor SOC restrictive condition, in the charge or discharge function that does not meet the next cut-off super capacitor of restrictive condition, dump power is exported by storage battery, this method has effectively been avoided overcharging of super capacitor or has been crossed the state of putting, reduced to greatest extent the requirement to accumulator cell charging and discharging simultaneously, improved super capacitor useful life, but the method is not considered overcharging of storage battery or is crossed the restriction of putting, may cause damage to storage battery, the output characteristic of this control method and ultracapacitor and storage battery is irrelevant simultaneously, so easily enter cut-off state and the performance index of micro-electrical network declined at super capacitor, and this method arranges buffering area before entering cut-off power stage when energy storage SOC is not met the demands, micro-grid stability is declined.

Summary of the invention

The present invention is the weak point of avoiding above-mentioned prior art to exist, a kind of meritorious classification distribution method that is applied to mixed energy storage system in micro-electrical network is provided, can effectively avoid overcharging and excessively putting of super capacitor and storage battery, reduce the cycle-index of storage battery, extend super capacitor and service lifetime of accumulator, improved stability and the performance index of micro-electrical network.

In order to achieve the above object, the technical solution adopted in the present invention is:

A kind of feature that is applied to the meritorious classification distribution method of mixed energy storage system in micro-electrical network of the present invention is: the micro-electrical network mixed energy storage system consisting of super capacitor energy-storage module, batteries to store energy module and energy storage tuning controller is set, and the method that described meritorious classification distributes is carried out as follows:

Step 1, described energy storage tuning controller receive the total active-power P of hybrid energy-storing target of microgrid energy management system output _s ^*, the output of described super capacitor energy-storage module super capacitor SOC measured value S _cstorage battery SOC measured value S with described batteries to store energy module output _b;

Step 2, the output characteristic based on super capacitor and storage battery are carried out first order distribution in described energy storage tuning controller;

By described hybrid energy-storing target gross power P _s ^*utilize formula (1) and formula (2) to be decomposed into meritorious high frequency change component P _cs1 ^*with meritorious level and smooth component P _bs1 ^*:

${P_{\mathrm{cs}1}}^{*}={P_s}^{*}-{P_s}^{*}\×\frac{1}{1+\mathrm{sT}}---\left(1\right)$

${P_{\mathrm{bs}1}}^{*}={P_s}^{*}\×\frac{1}{1+\mathrm{sT}}---\left(2\right)$

In formula (1) and formula (2), the oeprator that s is Laplace transformation, T is the inertia time constant setting;

Step 3, utilize power transfer regulation rule to described meritorious high frequency change component P _cs1 ^*carry out based on super capacitor SOC measured value S _cthe second level distribute, described power transfer regulation rule carries out as follows:

Step 3.1, calculating super capacitor power adjustment Δ P _cb:

The super capacitor electric discharge defining in described super capacitor energy-storage module is positive direction, P _scNfor super capacitor rated power, and P _scN>0, the power variation that described super capacitor is adjusted by power adjustment process is defined as power adjustment Δ P _cb, S _cminand S _cmaxbe respectively super capacitor SOC work lower limit and the super capacitor SOC work upper limit, setting super capacitor SOC crosses and puts early warning value is S ₁, it is S that super capacitor SOC overcharges early warning value ₂, the discharge power adjustment cutoff of setting super capacitor SOC is S ' ₁, to adjust cutoff be S ' to charge power ₂, make described super capacitor SOC measured value S _cwith power adjustment Δ P _cbfunction f (S _c) between pass be:

$f\left(S_c\right)=\left\{\begin{array}{cc}{f}_1\left(S_c\right),& S_{c\min }\&le;S_c\&le;S_1\\ 0,& S_1<S_c<S_2\\ f_2\left(S_c\right),& S_2\&le;S_c\&le;S_{c\max }\end{array}\right.---\left(3\right)$

In formula (3), f ₁(S _c) and f ₂(S _c) be all described super capacitor SOC value S _cmonotonically increasing function, establish power adjustment Δ P _cbby super-capacitor module, when battery module discharges, be positive direction, f ₁(S _c)≤0, and f ₂(S _c)>=0;

Make S _c(t) be t super capacitor SOC measured value S constantly _c, Δ P _cb(t) be t power adjustment constantly, and t=0 constantly, sets Δ P _cb(t)=0; If J ₁and J ₂for locking signal variable, and:

Work as J ₁=0 o'clock, intermediate variable H ₁=S ' ₁-S _c(t), intermediate variable Δ P ₁=Δ P _cb(t);

Work as J ₁=1 o'clock, intermediate variable H ₁with intermediate variable Δ P ₁locked;

Work as J ₂=0 o'clock, intermediate variable H ₂=S ' ₂-S _c(t), intermediate variable Δ P ₂=Δ P _cb(t);

Work as J ₂=1 o'clock, intermediate variable H ₂with intermediate variable Δ P ₂locked;

Described power adjustment Δ P _cbsampling process carry out as follows:

Step 3.1.1, utilize formula (3) to obtain t correlation function f (S constantly _c(t));

Step 3.1.2, by following situation, obtain t+1 power adjustment Δ P constantly respectively _cb(t+1):

Situation one: as S ' ₁≤ S _c(t)≤S ' ₂time, J is set ₁=0, J ₂=0, utilize formula (4) to obtain Δ P _cb(t+1):

ΔP _cb(t+1)=0 (4)

Situation two: work as S _cmin≤ S _c(t)≤S ₁time, J is set ₁=0, J ₂=0, utilize formula (5) to obtain Δ P _cb(t+1):

ΔP _cb(t+1)=(-1)MAX[|f(S _c(t))|,|ΔP _cb(t)|] （5）

Situation three: work as S ₁<S _c(t) <S ' ₁time:

If

j is set ₁=0, J ₂=0, by formula (6), obtain Δ P _cb(t+1):

ΔP _cb(t+1)=(-1)MAX[|f(S _c(t))|,|ΔP _cb(t)|] （6）

If

j is set ₁=1, J ₂=0, by formula (7), obtain Δ P _cb(t+1):

${\mathrm{\&Delta;P}}_{\mathrm{cb}}(t+1)=[S_1^{\&prime;}-S_c\left(t\right)]\frac{{\mathrm{\&Delta;P}}_1}{H_1}---\left(7\right)$

Situation four: work as S ₂≤ S _c(t)≤S _cmaxtime, J is set ₁=0, J ₂=0, by formula (8), obtain Δ P _cb(t+1):

ΔP _cb(t+1)=MAX[f(S _c(t)),ΔP _cb(t)] （8）

Situation five: as S ' ₂<S _c(t) <S ₂time,

If

j is set ₁=0, J ₂=0, by formula (9), obtain Δ P _cb(t+1):

ΔP _cb(t+1)=MAX[f(S _c(t)),ΔP _cb(t)] （9）

If j is set ₁=0, J ₂=1, by formula (10), obtain Δ P _cb(t+1):

${\mathrm{\&Delta;P}}_{\mathrm{cb}}(t+1)=[S_2^{\&prime;}-S_c\left(t\right)]\frac{{\mathrm{\&Delta;P}}_2}{H_2}---\left(10\right)$

Step 3.1.3, by described power adjustment Δ P _cb(t+1) assignment is to Δ P _cb;

Step 3.2, calculate the final goal power output P of described super capacitor _cs ^*:

By formula (11), obtained the preliminary target output P of super capacitor _cs2 ^*:

P _cs2 ^*=P _cs1 ^*+ΔP _cb （11）

By formula (12), obtained the final goal power output P of super capacitor _cs ^*:

${P_{\mathrm{cs}}}^{*}=\left\{\begin{array}{cc}{P}_{\mathrm{scN}},& {P_{\mathrm{cs}2}}^{*}\&GreaterEqual;P_{\mathrm{scN}}\\ {P_{\mathrm{cs}2}}^{*},& -P_{\mathrm{scN}}<{P_{\mathrm{cs}2}}^{*}<P_{\mathrm{scN}}\\ -P_{\mathrm{scN}},& {P_{\mathrm{cs}2}}^{*}\&le;-P_{\mathrm{scN}}\end{array}\right.---\left(12\right)$

Step 3.3, by formula (13), obtain the power transfer amount Δ P that super capacitor is transferred to storage battery _cs:

ΔP _cs=P _cs ^*-P _cs1 ^* （13）

Step 4, utilize power limiting regulation rule to meritorious level and smooth component P _bs1 ^*with power transfer amount Δ P _cscarry out based on storage battery SOC measured value S _bthe second level distribute, described power limiting regulation rule carries out as follows:

Step 4.1, utilize formula (14) to obtain based on storage battery SOC measured value S _bthe input variable P that distributes of the second level _bs2 ^*

P _bs2 ^*=P _bs1 ^*-ΔP _cs （14）

Step 4.2, acquisition storage battery power output limit value P _bmaxwith power lower limit P _bmin:

The battery discharging defining in described batteries to store energy module is positive direction, the storage battery SOC value of battery discharging cut-off point is a, it is b that storage battery is crossed the storage battery SOC value of putting early warning point, the storage battery SOC value of accumulator super-charge early warning point is c, the storage battery SOC value of charge in batteries cut-off point is d, have 0≤a<b<c<d≤1, the rated power of storage battery is P _sbN, and P _sbN>0, utilizes formula (15) and formula (16) to obtain respectively storage battery power output upper limit P _bmaxwith power lower limit P _bmin:

$P_{b\max }=\left\{\begin{array}{cc}0,& d\&le;S_b<1\\ P_{\mathrm{sbN}}\&times;\frac{d-S_b}{d-c},& c\&le;S_b<d\\ P_{\mathrm{sbN}},& 0<S_b<c\end{array}\right.---\left(15\right)$

$P_{b\min }=\left\{\begin{array}{cc}0,& 0<S_b\&le;a\\ -P_{\mathrm{sbN}}\&times;\frac{S_b-a}{b-a},& a<S_b\&le;b\\ -P_{\mathrm{sbN}},& b<S_b<1\end{array}\right.---\left(16\right)$

Step 4.3, utilize formula (17) to obtain the final goal power output P of storage battery _bs ^*:

${P_{\mathrm{bs}}}^{*}=\left\{\begin{array}{cc}{P}_{b\max },& {P_{\mathrm{bs}1}}^{*}\&GreaterEqual;P_{b\max }\\ {P_{\mathrm{bs}2}}^{*},& P_{b\min }<{P_{\mathrm{bs}2}}^{*}<P_{b\max }\\ P_{b\min },& {P_{\mathrm{bs}1}}^{*}\&le;P_{b\min }\end{array}\right.---\left(17\right)$

Step 4.4, utilize formula (18) to obtain the difference power Δ P after storage battery amplitude limit is adjusted _bs:

ΔP _bs=P _bs2 ^*-P _bs ^* （18）

Step 5, described energy storage tuning controller are by the final goal power output P of described super capacitor _cs ^*distribute to described super capacitor energy-storage module, by the final goal power output P of described storage battery _bs ^*distribute to described batteries to store energy module and described storage battery amplitude limit is adjusted after difference power Δ P _bsdistribute to described microgrid energy management system, complete thus described meritorious classification distribution method.

Compared with the prior art, beneficial effect of the present invention is embodied in:

The present invention is directed to the output characteristic of energy storage and the SOC of energy storage two specific characters in micro-electrical network, the meritorious classification distribution method of hybrid energy-storing has been proposed, first order power division makes super capacitor and storage battery bear respectively high frequency change component and the level and smooth component in hybrid energy-storing gross power, can be so that micro-electrical network has higher performance index energy, and enough reduce the cycle-index of storage battery, increasing storage battery service life; Second level power division makes can quickly recover to normal region by super capacitor SOC under the prerequisite that does not change the total output of hybrid energy-storing, can be so that micro-electrical network continues to have higher performance index, second level power distribution method can effectively be avoided overcharging of super capacitor and storage battery or cross putting, extend the useful life of super capacitor and storage battery, buffering area is set in power adjustment process to reduce the impact of energy storage chugging to micro-electrical network, has improved the stability of micro-electrical network.

Accompanying drawing explanation

Fig. 1 is the topology diagram of micro-electrical network under hybrid energy-storing involved in the present invention;

Fig. 2 is the principle assumption diagram of hybrid energy-storing active power two-stage distribution method involved in the present invention.

Embodiment

In the present embodiment, under mixed energy storage system, micro-electrical network comprises wind generator system, photovoltaic generating system, mixed energy storage system, the parts such as micro-electrical network load and microgrid energy management system, as shown in Figure 1, wherein photovoltaic generating system and wind generator system all adopt the control method of maximal power tracing output, can utilize to greatest extent solar energy and wind energy, micro-electrical network load is connected on micro-electrical network bus by power transmission line, microgrid energy management system is in charge of the energy flow of whole micro-electrical network, and the power stage of the modules in micro-electrical network is dispatched, it is the upper strata control system of the modules in micro-electrical network.Micro-electrical network mixed energy storage system that setting consists of super capacitor energy-storage module, batteries to store energy module and energy storage tuning controller, and by energy storage tuning controller, realize meritorious classification and distribute; The method that meritorious classification distributes is carried out as follows:

Step 1, energy storage tuning controller receive the total active-power P of hybrid energy-storing target of microgrid energy management system output _s ^*, super capacitor energy-storage module output super capacitor SOC measured value S _cstorage battery SOC measured value S with the output of batteries to store energy module _b;

Microgrid energy management system gathers power, load power, the electrical network of each distributed power generation unit in micro-electrical network and the power requirement of micro-electrical network points of common connection is determined to the target gross power P of mixed energy storage system _s ^*, by SOC detection module, draw super capacitor SOC measured value S _cwith storage battery SOC measured value S _b.

Step 2, the output characteristic based on super capacitor and storage battery are carried out first order distribution in energy storage tuning controller;

By hybrid energy-storing target gross power P _s ^*utilize formula (1) and formula (2) to be decomposed into meritorious high frequency change component P _cs1 ^*with meritorious level and smooth component P _bs1 ^*:

${P_{\mathrm{cs}1}}^{*}={P_s}^{*}-{P_s}^{*}\&times;\frac{1}{1+\mathrm{sT}}---\left(1\right)$

${P_{\mathrm{bs}1}}^{*}={P_s}^{*}\&times;\frac{1}{1+\mathrm{sT}}---\left(2\right)$

In formula (1) and formula (2), the oeprator that s is Laplace transformation, T is the inertia time constant setting;

The energy density of batteries to store energy is large, has the feature of large capacity, and still, storage battery output inertia is larger, and reaction speed is relatively slow, frequently discharges and recharges and can reduce its useful life; The features such as it is large that ultracapacitor has power density, has extended cycle life, and efficiency for charge-discharge is high, and charge-discharge velocity is fast, but its energy density is little.Therefore, the object of hybrid energy-storing first order power division is to make batteries to bear the smooth in gross output, super capacitor is applicable to bearing the high-frequency fluctuation part in gross output, this method can be so that micro-electrical network has higher performance index energy, and enough reduce the cycle-index of storage battery, increasing storage battery service life.

The first order is controlled, be intended to filter out low frequency component and the high fdrequency component in the output of energy-storage system gross power, weak point is not consider the factors such as the SOC of energy-storage system and Power Limitation, easily cause a certain unit of energy-storage system to overcharge, cross and put or transship, seriously reduced the useful life of energy-storage system.Therefore, be necessary, for the Output rusults of hybrid energy-storing first order control, the export target power of storage battery and ultracapacitor to be carried out to power adjustment.Storage battery energy density is large, and super capacitor energy density is less, is not changing under the prerequisite of hybrid energy-storing gross power, in the short time, super capacitor charge/discharge power transfer accumulators can be adjusted to super capacitor SOC, and little on the SOC impact of storage battery; And the gross power that only changes hybrid energy-storing within the long time could be adjusted the SOC of storage battery.Therefore, the object that the second level is controlled will be by super capacitor charge/discharge power transfer accumulators to adjust super capacitor SOC, and the power output by restriction storage battery also will limit result feedback to microgrid energy management system, make its gross power output of redistributing hybrid energy-storing, and then adjust the SOC of storage battery.

Step 3.1, calculating super capacitor power adjustment Δ P _cb:

Super capacitor electric discharge in definition super capacitor energy-storage module is positive direction, P _scNfor super capacitor rated power, and P _scN>0, the power variation that super capacitor is adjusted by power adjustment process is defined as power adjustment Δ P _cb, S _cminand S _cmaxbe respectively super capacitor SOC work lower limit and the super capacitor SOC work upper limit, setting super capacitor SOC crosses and puts early warning value is S ₁, it is S that super capacitor SOC overcharges early warning value ₂, make super capacitor SOC measured value S _cby S _cmin≤ S _c≤ S ₁and S ₂≤ S _c≤ S _cmaxthe power forming is adjusted in district and is carried out power adjustment, and the discharge power adjustment cutoff of setting super capacitor SOC is S ' ₁, to adjust cutoff be S ' to charge power ₂, make super capacitor SOC measured value S _cby S ₁≤ S _c≤ S ' ₁and S ' ₂≤ S _c≤ S ₂the power adjustment forming is eliminated in buffering area and is carried out power adjustment Δ P _cbgradually become 0 adjustment, make super capacitor SOC measured value S _cwith power adjustment Δ P _cbfunction f (S _c) between pass be:

$f\left(S_c\right)=\left\{\begin{array}{cc}{f}_1\left(S_c\right),& S_{c\min }\&le;S_c\&le;S_1\\ 0,& S_1<S_c<S_2\\ f_2\left(S_c\right),& S_2\&le;S_c\&le;S_{c\max }\end{array}\right.---\left(3\right)$

In formula (3), f ₁(S _c) and f ₂(S _c) be all super capacitor SOC value S _cmonotonically increasing function, establish power adjustment Δ P _cbby super-capacitor module, when battery module discharges, be positive direction, f ₁(S _c)≤0, and f ₂(S _c)>=0;

Make S _c(t) be t super capacitor SOC measured value S constantly _c, Δ P _cb(t) be t power adjustment constantly, and t=0 constantly, sets Δ P _cb(t)=0; If J ₁and J ₂for locking signal variable, and:

Work as J ₁=0 o'clock, intermediate variable H ₁=S ' ₁-S _c(t), intermediate variable Δ P ₁=Δ P _cb(t);

Work as J ₁=1 o'clock, intermediate variable H ₁with intermediate variable Δ P ₁locked;

Work as J ₂=0 o'clock, intermediate variable H ₂=S ' ₂-S _c(t), intermediate variable Δ P ₂=Δ P _cb(t);

Work as J ₂=1 o'clock, intermediate variable H ₂with intermediate variable Δ P ₂locked;

Power adjustment Δ P _cbsampling process carry out as follows:

Step 3.1.1, utilize formula (3) to obtain t correlation function f (S constantly _c(t));

Step 3.1.2, by following situation, obtain t+1 power adjustment Δ P constantly respectively _cb(t+1):

Situation one: as S ' ₁≤ S _c(t)≤S ' ₂time, J is set ₁=0, J ₂=0, utilize formula (4) to obtain Δ P _cb(t+1):

ΔP _cb(t+1)=0 (4)

Now super capacitor SOC is interval in best effort, without power, shifts.

Situation two: work as S _cmin≤ S _c(t)≤S ₁time, be called power and adjust charging zone, J is set ₁=0, J ₂=0, sharp

By formula (5), obtain Δ P _cb(t+1):

ΔP _cb(t+1)=(-1)MAX[|f(S _c(t))|,|ΔP _cb(t)|] （5）

Now super capacitor SOC is too low, needs to supplement electric weight, Δ P _cb(t+1) take rapid Optimum super capacitor SOC as object value, make super capacitor SOC shift out as early as possible this interval.

Situation three: work as S ₁<S _c(t) <S ' ₁time, be called power adjustment charging transition region,

If

j is set ₁=0, J ₂=0, by formula (6), obtain Δ P _cb(t+1):

ΔP _cb(t+1)=(-1)MAX[|f(S _c(t))|,|ΔP _cb(t)|] （6）

Now super capacitor SOC moves gradually to power adjustment charging zone, Δ P _cb(t+1) take rapid adjustment super capacitor SOC as ascendant trend be object value.

If

j is set ₁=1, J ₂=0, by formula (7), obtain Δ P _cb(t+1):

${\mathrm{\&Delta;P}}_{\mathrm{cb}}(t+1)=[S_1^{\&prime;}-S_c\left(t\right)]\frac{{\mathrm{\&Delta;P}}_1}{H_1}---\left(7\right)$

Now super capacitor SOC adjusts charging zone away from power gradually, by Δ P _cb(t+1) gradually become 0, avoid Δ P _cb(t+1) sudden change causes the impact of micro-electrical network, has improved the stability of micro-electrical network.

Situation four: work as S ₂≤ S _c(t)≤S _cmaxtime, be called power and adjust region of discharge, J is set ₁=0, J ₂=0, by formula (8), obtain Δ P _cb(t+1):

ΔP _cb(t+1)=MAX[f(S _c(t)),ΔP _cb(t)] （8）

Now super capacitor SOC is too high, need emit electric weight, Δ P _cb(t+1) take rapid Optimum super capacitor SOC as object value, make super capacitor SOC shift out as early as possible this interval.

Situation five: as S ' ₂<S _c(t) <S ₂time, be called power adjustment electric discharge transition region,

If j is set ₁=0, J ₂=0, by formula (9), obtain Δ P _cb(t+1):

ΔP _cb(t+1)=MAX[f(S _c(t)),ΔP _cb(t)] （9）

Now super capacitor SOC moves gradually to power adjustment region of discharge, Δ P _cb(t+1) take rapid adjustment super capacitor SOC as downward trend be object value.

If

j is set ₁=0, J ₂=1, by formula (10), obtain Δ P _cb(t+1):

${\mathrm{\&Delta;P}}_{\mathrm{cb}}(t+1)=[S_2^{\&prime;}-S_c\left(t\right)]\frac{{\mathrm{\&Delta;P}}_2}{H_2}---\left(10\right)$

Now super capacitor SOC adjusts region of discharge away from power gradually, by Δ P _cb(t+1) gradually become 0, avoid Δ P _cb(t+1) sudden change causes the impact of micro-electrical network, has improved the stability of micro-electrical network.

Step 3.1.3, by power adjustment Δ P _cb(t+1) assignment is to Δ P _cb;

By the above-mentioned power to super capacitor, adjust, can make super capacitor SOC value S _cfor a long time in ideal operation district, the output of super capacitor is not cut off, thereby can continue to make micro-electrical network to obtain higher performance index, after fast quick-recovery super capacitor SOC, buffer strip is set makes power adjustment gradually become 0, thereby effectively avoided removing the impact that power adjustment causes micro-electrical network, improved the stability of micro-electrical network.

The final goal power output P of step 3.2, calculating super capacitor _cs ^*:

By formula (11), obtained the preliminary target output P of super capacitor _cs2 ^*:

P _cs2 ^*=P _cs1 ^*+ΔP _cb （11）

By P _cs2 ^*through super capacitor rated power P _scNrestriction, by the final goal power output P of formula (12) acquisition super capacitor _cs ^*:

${P_{\mathrm{cs}}}^{*}=\left\{\begin{array}{cc}{P}_{\mathrm{scN}},& {P_{\mathrm{cs}2}}^{*}\&GreaterEqual;P_{\mathrm{scN}}\\ {P_{\mathrm{cs}2}}^{*},& -P_{\mathrm{scN}}<{P_{\mathrm{cs}2}}^{*}<P_{\mathrm{scN}}\\ -P_{\mathrm{scN}},& {P_{\mathrm{cs}2}}^{*}\&le;-P_{\mathrm{scN}}\end{array}\right.---\left(12\right)$

This process has effectively been avoided overcharging of super capacitor or has crossed putting, thereby makes super capacitor injury-free;

Step 3.3, by formula (13), obtain the power transfer amount Δ P that super capacitor is transferred to storage battery _cs:

ΔP _cs=P _cs ^*-P _cs1 ^* （13）

Step 4, utilize power limiting regulation rule to meritorious level and smooth component P _bs1 ^*with power transfer amount Δ P _cscarry out based on storage battery SOC measured value S _bthe second level distribute, power limiting regulation rule carries out as follows:

Step 4.1, utilize formula (14) to obtain based on storage battery SOC measured value S _bthe input variable P that distributes of the second level _bs2 ^*

P _bs2 ^*=P _bs1 ^*-ΔP _cs （14）

Δ P in step 3 _csthe high frequency change component that distributes of the first order and the difference of super capacitor final goal power output, Δ P _csbe one and take the amount that super capacitor is positive direction to battery discharging, to transfer in storage battery output control, be that the data direction of positive direction is contrary with the charge in batteries that sets during storage battery power is controlled, it and meritorious level and smooth component form the original input variable of storage battery power signal jointly.

Step 4.2, acquisition storage battery power output limit value P _bmaxwith power lower limit P _bmin:

Battery discharging in definition batteries to store energy module is positive direction, the storage battery SOC value of battery discharging cut-off point is a, it is b that storage battery is crossed the storage battery SOC value of putting early warning point, the storage battery SOC value of accumulator super-charge early warning point is c, the storage battery SOC value of charge in batteries cut-off point is d, have 0≤a<b<c<d≤1, the rated power of storage battery is P _sbN, and P _sbN>0, utilizes formula (15) and formula (16) to obtain respectively storage battery power output upper limit P _bmaxwith power lower limit P _bmin:

$P_{b\max }=\left\{\begin{array}{cc}0,& d\&le;S_b<1\\ P_{\mathrm{sbN}}\&times;\frac{d-S_b}{d-c},& c\&le;S_b<d\\ P_{\mathrm{sbN}},& 0<S_b<c\end{array}\right.---\left(15\right)$

$P_{b\min }=\left\{\begin{array}{cc}0,& 0<S_b\&le;a\\ -P_{\mathrm{sbN}}\&times;\frac{S_b-a}{b-a},& a<S_b\&le;b\\ -P_{\mathrm{sbN}},& b<S_b<1\end{array}\right.---\left(16\right)$

Step 4.3, the total active power of storage battery is carried out to Power Limitation, utilize formula (17) to obtain the final goal power output P of storage battery _bs ^*:

${P_{\mathrm{bs}}}^{*}=\left\{\begin{array}{cc}{P}_{b\max },& {P_{\mathrm{bs}1}}^{*}\&GreaterEqual;P_{b\max }\\ {P_{\mathrm{bs}2}}^{*},& P_{b\min }<{P_{\mathrm{bs}2}}^{*}<P_{b\max }\\ P_{b\min },& {P_{\mathrm{bs}1}}^{*}\&le;P_{b\min }\end{array}\right.---\left(17\right)$

Due to P _bs2 ^*the Power Limitation that may surpass storage battery, causes according to target power stage of storage battery, will cause the power fluctuation of micro-electrical network, so need to be by P _bs2 ^*after the Power Limitation of storage battery, obtain the target output value P of storage battery _bs ^*.

Step 4.4, utilize formula (18) to obtain the difference power Δ P after storage battery amplitude limit is adjusted _bs:

ΔP _bs=P _bs2 ^*-P _bs ^* （18）

Step 5, energy storage tuning controller are by the final goal power output P of super capacitor _cs ^*distribute to super capacitor energy-storage module, by the final goal power output P of storage battery _bs ^*distribute to batteries to store energy module and storage battery amplitude limit is adjusted after difference power Δ P _bsdistribute to microgrid energy management system, complete thus the meritorious classification distribution method of hybrid energy-storing.

Energy storage tuning controller is by the final goal power output P of super capacitor _cs ^*distribute to super capacitor energy-storage module, by the final goal power output P of storage battery _bs ^*distributing to batteries to store energy module, is the final purpose to the meritorious classification distribution method of hybrid energy-storing module; Meanwhile, by difference power Δ P _bsoutput feeds back to microgrid energy management system, makes it adjust micro-grid power structure and changes the total active power demand of micro-electrical network to hybrid energy-storing, and then optimize storage battery SOC, avoids overcharging or excessively putting of storage battery, thus increasing storage battery service life.

To sum up, as shown in Figure 2, energy storage tuning controller receives the total active-power P of hybrid energy-storing that microgrid energy management system is sent to the control principle drawing of the active power classification distribution method of hybrid energy-storing _s ^*, utilize the meritorious classification distribution method of hybrid energy-storing provided by the invention to distribute it, wherein first order distribution is to utilize low-pass first order filter to isolate the total active-power P of hybrid energy-storing _s ^*in meritorious high frequency change component P _cs1 ^*with meritorious level and smooth component P _bs1 ^*, its objective is the meritorious high frequency change component P in total active power of utilizing super capacitor to export hybrid energy-storing _cs1 ^*, storage battery is only exported the meritorious level and smooth component P in the total active power of hybrid energy-storing _bs1 ^*thereby, reduce accumulator cell charging and discharging ring number of times, improve service lifetime of accumulator, can also improve the performance index of micro-electrical network simultaneously; It is respectively that the power first order being distributed based on super capacitor SOC and storage battery SOC limits and optimizes that the second level is distributed, based on super capacitor SOC to meritorious high frequency change component P _cs1 ^*carry out power transfer adjustment, by power transfer amount Δ P _cstransfer to storage battery output, be used for optimizing super capacitor SOC, and obtain the final goal power output P after super capacitor is optimized _cs ^*its object is adjusted to super capacitor SOC in rational working range exactly, so that super capacitor can normally be worked, make micro-electrical network keep higher performance index, avoid overcharging or crossing to put super capacitor is caused to damage because of super capacitor, in super capacitor SOC recovery process, for different situations, set the buffer strip of rapid Optimum and elimination adjustment amount, improve performance index and the stability of micro-electrical network; Based on storage battery SOC to meritorious level and smooth component P _bs1 ^*with with power transfer amount Δ P _csand carry out power limiting adjustment, obtain the final goal power output P of storage battery _bs ^*difference power Δ P after adjusting with storage battery limit value _bs, its object is exactly that the SOC of storage battery is adjusted in rational working range, avoids overcharging or excessively putting of storage battery, extends the useful life of storage battery; The final goal power output that finally obtains super-capacitor module and battery module is distributed in the second level, also draw the difference power after storage battery amplitude limit is adjusted simultaneously, and fed back to microgrid energy management system, so that micro-electrical network is adjusted the gross power output demand of hybrid energy-storing, also make the active power distribution of whole energy-storage system form a closed-loop control system simultaneously, thereby improved stability and the reliability of micro-electrical network.

Claims (1)

1. a meritorious classification distribution method that is applied to mixed energy storage system in micro-electrical network, it is characterized in that: the micro-electrical network mixed energy storage system consisting of super capacitor energy-storage module, batteries to store energy module and energy storage tuning controller is set, and the method that described meritorious classification distributes is carried out as follows:

Step 1, described energy storage tuning controller receive the total active-power P of hybrid energy-storing target of microgrid energy management system output _s ^*, the output of described super capacitor energy-storage module super capacitor SOC measured value S _cstorage battery SOC measured value S with described batteries to store energy module output _b;

Step 2, the output characteristic based on super capacitor and storage battery are carried out first order distribution in described energy storage tuning controller;

By described hybrid energy-storing target gross power P _s ^*utilize formula (1) and formula (2) to be decomposed into meritorious high frequency change component P _cs1 ^*with meritorious level and smooth component P _bs1 ^*:

${P_{\mathrm{cs}1}}^{*}={P_s}^{*}-{P_s}^{*}\&times;\frac{1}{1+\mathrm{sT}}---\left(1\right)$

${P_{\mathrm{bs}1}}^{*}={P_s}^{*}\&times;\frac{1}{1+\mathrm{sT}}---\left(2\right)$

In formula (1) and formula (2), the oeprator that s is Laplace transformation, T is the inertia time constant setting;

Step 3, utilize power transfer regulation rule to described meritorious high frequency change component P _cs1 ^*carry out based on super capacitor SOC measured value S _cthe second level distribute, described power transfer regulation rule carries out as follows:

Step 3.1, calculating super capacitor power adjustment Δ P _cb:

The super capacitor electric discharge defining in described super capacitor energy-storage module is positive direction, P _scNfor super capacitor rated power, and P _scN>0, the power variation that described super capacitor is adjusted by power adjustment process is defined as power adjustment Δ P _cb, S _cminand S _cmaxbe respectively super capacitor SOC work lower limit and the super capacitor SOC work upper limit, setting super capacitor SOC crosses and puts early warning value is S ₁, it is S that super capacitor SOC overcharges early warning value ₂, the discharge power adjustment cutoff of setting super capacitor SOC is S ' ₁, to adjust cutoff be S ' to charge power ₂, make described super capacitor SOC measured value S _cwith power adjustment Δ P _cbfunction f (S _c) between pass be:

$f\left(S_c\right)=\left\{\begin{array}{cc}{f}_1\left(S_c\right),& S_{c\min }\&le;S_c\&le;S_1\\ 0,& S_1<S_c<S_2\\ f_2\left(S_c\right),& S_2\&le;S_c\&le;S_{c\max }\end{array}\right.---\left(3\right)$

In formula (3), f ₁(S _c) and f ₂(S _c) be all described super capacitor SOC value S _cmonotonically increasing function, establish power adjustment Δ P _cbby super-capacitor module, when battery module discharges, be positive direction, f ₁(S _c)≤0, and f ₂(S _c)>=0;

Make S _c(t) be t super capacitor SOC measured value S constantly _c, Δ P _cb(t) be t power adjustment constantly, and t=0 constantly, sets Δ P _cb(t)=0; If J ₁and J ₂for locking signal variable, and:

Work as J ₁=0 o'clock, intermediate variable H ₁=S ' ₁-S _c(t), intermediate variable Δ P ₁=Δ P _cb(t);

Work as J ₁=1 o'clock, intermediate variable H ₁with intermediate variable Δ P ₁locked;

Work as J ₂=0 o'clock, intermediate variable H ₂=S ' ₂-S _c(t), intermediate variable Δ P ₂=Δ P _cb(t);

Work as J ₂=1 o'clock, intermediate variable H ₂with intermediate variable Δ P ₂locked;

Described power adjustment Δ P _cbsampling process carry out as follows:

Step 3.1.1, utilize formula (3) to obtain t correlation function f (S constantly _c(t));

Step 3.1.2, by following situation, obtain t+1 power adjustment Δ P constantly respectively _cb(t+1):

Situation one: as S ' ₁≤ S _c(t)≤S ' ₂time, J is set ₁=0, J ₂=0, utilize formula (4) to obtain Δ P _cb(t+1):

ΔP _cb(t+1)=0 (4)

Situation two: work as S _cmin≤ S _c(t)≤S ₁time, J is set ₁=0, J ₂=0, utilize formula (5) to obtain Δ P _cb(t+1):

ΔP _cb(t+1)=(-1)MAX[|f(S _c(t))|,|ΔP _cb(t)|] （5）

Situation three: work as S ₁<S _c(t) <S ' ₁time:

If

j is set ₁=0, J ₂=0, by formula (6), obtain Δ P _cb(t+1):

ΔP _cb(t+1)=(-1)MAX[|f(S _c(t))|,|ΔP _cb(t)|] （6）

If

j is set ₁=1, J ₂=0, by formula (7), obtain Δ P _cb(t+1):

${\mathrm{\&Delta;P}}_{\mathrm{cb}}(t+1)=[S_1^{\&prime;}-S_c\left(t\right)]\frac{{\mathrm{\&Delta;P}}_1}{H_1}---\left(7\right)$

Situation four: work as S ₂≤ S _c(t)≤S _cmaxtime, J is set ₁=0, J ₂=0, by formula (8), obtain Δ P _cb(t+1):

ΔP _cb(t+1)=MAX[f(S _c(t)),ΔP _cb(t)] （8）

Situation five: as S ' ₂<S _c(t) <S ₂time,

If

j is set ₁=0, J ₂=0, by formula (9), obtain Δ P _cb(t+1):

ΔP _cb(t+1)=MAX[f(S _c(t)),ΔP _cb(t)] （9）

If

j is set ₁=0, J ₂=1, by formula (10), obtain Δ P _cb(t+1):

${\mathrm{\&Delta;P}}_{\mathrm{cb}}(t+1)=[S_2^{\&prime;}-S_c\left(t\right)]\frac{{\mathrm{\&Delta;P}}_2}{H_2}---\left(10\right)$

Step 3.1.3, by described power adjustment Δ P _cb(t+1) assignment is to Δ P _cb;

Step 3.2, calculate the final goal power output P of described super capacitor _cs ^*:

By formula (11), obtained the preliminary target output P of super capacitor _cs2 ^*:

P _cs2 ^*=P _cs1 ^*+ΔP _cb （11）

By formula (12), obtained the final goal power output P of super capacitor _cs ^*:

${P_{\mathrm{cs}}}^{*}=\left\{\begin{array}{cc}{P}_{\mathrm{scN}},& {P_{\mathrm{cs}2}}^{*}\&GreaterEqual;P_{\mathrm{scN}}\\ {P_{\mathrm{cs}2}}^{*},& -P_{\mathrm{scN}}<{P_{\mathrm{cs}2}}^{*}<P_{\mathrm{scN}}\\ -P_{\mathrm{scN}},& {P_{\mathrm{cs}2}}^{*}\&le;-P_{\mathrm{scN}}\end{array}\right.---\left(12\right)$

Step 3.3, by formula (13), obtain the power transfer amount Δ P that super capacitor is transferred to storage battery _cs:

ΔP _cs=P _cs ^*-P _cs1 ^* （13）

Step 4, utilize power limiting regulation rule to meritorious level and smooth component P _bs1 ^*with power transfer amount Δ P _cscarry out based on storage battery SOC measured value S _bthe second level distribute, described power limiting regulation rule carries out as follows:

Step 4.1, utilize formula (14) to obtain based on storage battery SOC measured value S _bthe input variable P that distributes of the second level _bs2 ^*

P _bs2 ^*=P _bs1 ^*-ΔP _cs （14）

Step 4.2, acquisition storage battery power output limit value P _bmaxwith power lower limit P _bmin:

The battery discharging defining in described batteries to store energy module is positive direction, the storage battery SOC value of battery discharging cut-off point is a, it is b that storage battery is crossed the storage battery SOC value of putting early warning point, the storage battery SOC value of accumulator super-charge early warning point is c, the storage battery SOC value of charge in batteries cut-off point is d, have 0≤a<b<c<d≤1, the rated power of storage battery is P _sbN, and P _sbN>0, utilizes formula (15) and formula (16) to obtain respectively storage battery power output upper limit P _bmaxwith power lower limit P _bmin:

$P_{b\max }=\left\{\begin{array}{cc}0,& d\&le;S_b<1\\ P_{\mathrm{sbN}}\&times;\frac{d-S_b}{d-c},& c\&le;S_b<d\\ P_{\mathrm{sbN}},& 0<S_b<c\end{array}\right.---\left(15\right)$

$P_{b\min }=\left\{\begin{array}{cc}0,& 0<S_b\&le;a\\ -P_{\mathrm{sbN}}\&times;\frac{S_b-a}{b-a},& a<S_b\&le;b\\ -P_{\mathrm{sbN}},& b<S_b<1\end{array}\right.---\left(16\right)$

Step 4.3, utilize formula (17) to obtain the final goal power output P of storage battery _bs ^*:

${P_{\mathrm{bs}}}^{*}=\left\{\begin{array}{cc}{P}_{b\max },& {P_{\mathrm{bs}1}}^{*}\&GreaterEqual;P_{b\max }\\ {P_{\mathrm{bs}2}}^{*},& P_{b\min }<{P_{\mathrm{bs}2}}^{*}<P_{b\max }\\ P_{b\min },& {P_{\mathrm{bs}1}}^{*}\&le;P_{b\min }\end{array}\right.---\left(17\right)$

Step 4.4, utilize formula (18) to obtain the difference power Δ P after storage battery amplitude limit is adjusted _bs:

ΔP _bs=P _bs2 ^*-P _bs ^* （18）

Step 5, described energy storage tuning controller are by the final goal power output P of described super capacitor _cs ^*distribute to described super capacitor energy-storage module, by the final goal power output P of described storage battery _bs ^*distribute to described batteries to store energy module and described storage battery amplitude limit is adjusted after difference power Δ P _bsdistribute to described microgrid energy management system, complete thus described meritorious classification distribution method.