CN104300567A - Hybrid energy storage control method for stabilizing intermittent power supply power fluctuation - Google Patents

Abstract

The invention discloses a hybrid energy storage control method for stabilizing intermittent power supply power fluctuation. According to the method, a super capacitor with large power density and high dynamic response speed is adopted as system buffer stored energy for preferentially stabilizing the power fluctuation, and the voltage of the super capacitor is prevented from being out of limit by adjusting the power of a storage battery set. The storage battery set is divided into a charge set and a discharge set which are independent and are controlled respectively, and the circulating charge and discharge frequency of the storage battery set is reduced to the maximum extent. Based on the mutual adjustment rule of the charge set and the discharge set of the storage battery set of a charge state, the storage battery set is prevented from being deeply charged or discharged, and the service life of the storage battery set is prolonged.

Description

A kind of hybrid energy-storing control method stabilizing the fluctuation of intermittent power

Technical field

The present invention relates to the hybrid energy-storing control method stabilizing the fluctuation of intermittent power, belong to micro-capacitance sensor energy storage technology.

Background technology

Because the fluctuation of the intermittent output power of power supply such as wind-powered electricity generation, photovoltaic is large, the feature that randomness is strong, needs the power fluctuation problem that energy storage device brings to stabilize intermittent power supply in microgrid.Traditional method adopts single batteries to store energy element to realize stabilizing of system power, but because discharge and recharge frequently often can not meet on the impact of battery life and single energy-storage travelling wave tube the needs that system power stabilizes, storage battery and super capacitor are had complementary advantages and are formed the power adjustments ability that mixed energy storage system strengthens energy-storage system by the present invention, utilize that super capacitor power density is large, discharge and recharge feature often preferentially stabilizes power fluctuation, maintain super-capacitor voltage within limit value by the subsequent adjustment of batteries.Charge in batteries group and discharge composition are not independently controlled, and based on batteries state-of-charge, charging group and electric discharge group is mutually adjusted, to optimize batteries charge and discharge process, extend energy-storage travelling wave tube useful life.

Summary of the invention

Goal of the invention: the problem large for intermittent output power of power supply fluctuation, randomness is strong, and the harmful effect that the frequent discharge and recharge of single batteries causes battery life, the invention provides a kind of hybrid energy-storing control method stabilizing the fluctuation of intermittent power, the power adjustments ability of energy-storage system is strengthened by composition mixed energy storage system of storage battery and super capacitor being had complementary advantages, batteries is divided into charging group and electric discharge group simultaneously, effectively raises the life-span of batteries.

Technical scheme: for achieving the above object, the technical solution used in the present invention is:

A kind of hybrid energy-storing control method stabilizing the fluctuation of intermittent power, hybrid energy-storing is formed by batteries and super capacitor, batteries is divided into independent two the storage battery groupings controlled, the grouping of each group storage battery includes more than one storage battery, two group storage batteries is called the first batteries and the second batteries; Super capacitor, the first batteries and the second batteries are connected on the DC bus of hybrid energy-storing by two-way DC/DC converter respectively, realize the double-direction control of super capacitor, the first batteries and the second batteries; The DC bus of hybrid energy-storing is connected on public electric wire net by DC/AC converter, and intermittent power supply is connected on public electric wire net by DC/AC converter; The target stabilizing the power fluctuation of intermittent power supply be utilize hybrid energy-storing absorb intermittent power supply exert oneself in wave portion, make intermittent power grid power smooth; Batteries adopts the batteries based on state-of-charge to mutually adjust rule and realizes state control, is specially:

Using the first batteries as charging accumulator group, using the second batteries as electric discharge batteries, storage battery in charging accumulator group is in charged state or charging complete state, and the storage battery in electric discharge batteries is in discharge condition or waits for discharge condition; Prescribe a time limit under the state-of-charge of the part or all of storage battery in electric discharge batteries arrives state-of-charge, regulate this part or all of storage battery to charging accumulator group, the part or all of storage battery reaching the state-of-charge upper limit in charging accumulator group is adjusted to electric discharge batteries simultaneously, redistribute charging accumulator group and electric discharge batteries, form the first new batteries and the second batteries; In electric discharge batteries, some storage batterys that variety of priority driven carrying capacity is minimum or the overall mode exported with rated power of electric discharge batteries regulate super-capacitor voltage within nominal working range; In charging accumulator group, some storage batterys that variety of priority driven carrying capacity is maximum or charging accumulator group entirety enter electric discharge batteries.

Preferably, the two-way DC/DC converter be connected with super capacitor adopts the Double-loop Control Strategy of outer voltage, current inner loop, the two-way DC/DC converter be connected with storage battery to adopt the control strategy of power outer shroud, current inner loop.

Preferably, the target stabilizing the power fluctuation of intermittent power supply be utilize hybrid energy-storing absorb intermittent power supply exert oneself in wave portion, make intermittent power grid power smooth, be specially:

P _s＝P _g+P _h

Wherein, P _gfor intermittent power supply is exerted oneself, P _hfor hybrid energy-storing stabilizes power, P _sfor stabilizing rear intermittent power grid power; Exert oneself intermittent power supply P _gdeduct the level and smooth component obtained through low-pass filtering to be hybrid energy-storing and to stabilize power P _h, transfer function is:

$P_h\left(s\right)=-\frac{T_{g}s}{1+T_{g}s}{P}_g\left(s\right)$

Wherein, T _gfor time constant filter.

Preferably, hybrid energy-storing AC DC/AC converter adopts PQ to control (P is active power, and Q is reactive power) mode and exports P _hto stabilize the power fluctuation of intermittent power supply, super capacitor, the first batteries and the second batteries carry out Power Exchange by the DC bus of two-way DC/DC converter and hybrid energy-storing, use mixed energy storage system energy control method to control super-capacitor voltage within limit value; In order to control super-capacitor voltage within upper lower limit value, i.e. U _{sc_min}<U _sc<U _{sc_max}, as super-capacitor voltage U _scarrive the pre-control value U of the upper limit _{sc_up}or the pre-control value U of lower limit _{sc_down}time, make super-capacitor voltage U by the adjustment of the first batteries and the second batteries _scwithin being returned to upper lower limit value; Wherein, U _{sc_min}<U _{sc_down}<U _sc<U _{sc_up}<U _{sc_max}, U _{sc_min}for super-capacitor voltage lower limit, U _scfor super-capacitor voltage value, U _{sc_max}for super-capacitor voltage higher limit.

Preferably, after being regulated by the first batteries and the second batteries, super-capacitor voltage recovery value is designated as U _{sc_ref}, the discharge and recharge rated power of the first batteries and the second batteries is designated as P _cbat, P _dbat, mixed energy storage system energy control method is specially:

(1) U is worked as _sc≤ U _{sc_down}, super-capacitor voltage reaches the pre-control value of lower limit, now m=1, and charging accumulator group does not work, and electric discharge batteries is with rated power P _dbatsend power, until super-capacitor voltage returns to set point U _{sc_ref};

(2) U is worked as _sc>=U _{sc_up}, super-capacitor voltage reaches the pre-control value of the upper limit, now m=3, and electric discharge batteries does not work, and charging accumulator group is with rated power P _cbatabsorbed power, until super-capacitor voltage returns to set point U _{sc_ref};

(3) U is worked as _{sc_down}<U _sc<U _{sc_up}, super-capacitor voltage is in normal range (NR), and the power carrying out intermittent power supply by super capacitor is separately stabilized, now m=2, and charging accumulator group and electric discharge batteries all do not work.

Preferably, the state-of-charge lower limit of the first batteries and the second batteries is designated as SOC _up, the state-of-charge upper limit of the first batteries and the second batteries is designated as SOC _down, the state-of-charge of charging accumulator group is designated as SOC _cbat, the state-of-charge of electric discharge batteries is designated as SOC _dbat, the batteries based on state-of-charge is mutually adjusted rule and is specially:

(1) SOC is worked as _cbat≤ SOC _upand SOC _dbat>=SOC _downtime, charging accumulator group, electric discharge batteries do not adjust, and carry out separately independently charge and discharge control, to maintain super-capacitor voltage in normal range (NR) according to super-capacitor voltage size;

(2) SOC is worked as _cbat>SOC _upor SOC _dbat<SOC _downtime, show that charging accumulator group reaches charging adjustment state or electric discharge batteries reaches electric discharge adjustment state, now charging accumulator group and electric discharge batteries are mutually adjusted, to avoid the discharge and recharge of the batteries degree of depth, make the capacity of batteries utilize optimization simultaneously.

Beneficial effect: the hybrid energy-storing control method stabilizing the fluctuation of intermittent power provided by the invention, batteries is divided into the independent charging accumulator group controlled and electric discharge batteries under the condition that capacity is constant, independently control, decrease batteries discharge and recharge number of times, effectively improve the reduced lifetime problem that batteries discharge and recharge frequently causes.

Accompanying drawing explanation

Fig. 1 of the present inventionly stabilizes system block diagram;

Fig. 2 is super capacitor DC/DC control block diagram;

Fig. 3 is batteries DC/DC control block diagram;

Fig. 4 is mixed energy storage system energy control method block diagram;

Fig. 5 mutually adjusts regular block diagram based on the batteries of state-of-charge;

Fig. 6 (a) is intermittent DG power curve;

Fig. 6 (b) is hybrid energy-storing power curve;

Fig. 6 (c) is for stabilizing rear system grid connection power curve;

Fig. 7 is hybrid energy-storing DC bus-bar voltage curve;

Fig. 8 (a) is super-capacitor voltage curve;

Storage battery charge and discharge group state-of-charge change curve when Fig. 8 (b) is independent control;

Battery discharging group state-of-charge change curve when Fig. 8 (c) is independent control;

Fig. 8 (d) is batteries state-of-charge change curve during unified control;

Fig. 9 is the inventive method flow chart.

Embodiment

Below in conjunction with accompanying drawing, the present invention is further described.

Be illustrated in figure 1 and a kind ofly stabilize system based on hybrid energy-storing, a kind of hybrid energy-storing control method stabilizing the fluctuation of intermittent power, hybrid energy-storing is formed by batteries and super capacitor, batteries is divided into independent two the storage battery groupings controlled, the grouping of each group storage battery includes more than one storage battery, two group storage batteries is called the first batteries and the second batteries; Super capacitor, the first batteries and the second batteries are connected on the DC bus of hybrid energy-storing by two-way DC/DC converter respectively, realize the double-direction control of super capacitor, the first batteries and the second batteries; The DC bus of hybrid energy-storing is connected on public electric wire net by DC/AC converter, and intermittent DG (Distributed Generation, distributed generator) is connected on public electric wire net by DC/AC converter; Batteries can adopt the model of ideal source and internal resistance series connection, the model that super capacitor can adopt ideal capacitance and resistance to be in series.

The two-way DC/DC converter (DC/DC (C)) be connected with super capacitor adopts the Double-loop Control Strategy of outer voltage, current inner loop, as shown in Figure 2; Utilize the feature that super capacitor rapid dynamic response speed, power density are large, control fast and stable DC bus-bar voltage by outer voltage, ensure that DC/AC converter stabilizes requirement steady operation according to system; The buffering leveling of super capacitor can avoid the frequent discharge and recharge of batteries, reduces the power index requirement of batteries simultaneously.The two-way DC/DC converter (DC/DC (E be connected with storage battery _c), DC/DC (E _d)) adopt the control strategy of power outer shroud, current inner loop, as shown in Figure 3; Storage battery energy density is large, as follow-up energy storage, according to super-capacitor voltage U _scadjustment need, controlled by power outer shroud, the first batteries and the second batteries regulate super-capacitor voltage within nominal working range in the mode that rated power exports.

The target stabilizing the power fluctuation of intermittent DG be utilize hybrid energy-storing absorb intermittent DG exert oneself in wave portion, make the grid-connected power smooth of intermittent DG; Be specially:

P _s＝P _g+P _h

Wherein, P _gfor intermittent power supply is exerted oneself, P _hfor hybrid energy-storing stabilizes power, P _sfor stabilizing rear intermittent power grid power; Exert oneself intermittent power supply P _gdeduct the level and smooth component obtained through low-pass filtering to be hybrid energy-storing and to stabilize power P _h, transfer function is:

$P_h\left(s\right)=-\frac{T_{g}s}{1+T_{g}s}{P}_g\left(s\right)$

Wherein, T _gfor time constant filter.

Hybrid energy-storing AC DC/AC converter adopts PQ to control (P is active power, and Q is reactive power) mode and exports P _hto stabilize the power fluctuation of intermittent DG, super capacitor, the first batteries and the second batteries carry out Power Exchange by the DC bus of two-way DC/DC converter and hybrid energy-storing, use mixed energy storage system energy control method to control super-capacitor voltage within limit value; In order to control super-capacitor voltage within upper lower limit value, i.e. U _{sc_min}<U _sc<U _{sc_max}, as super-capacitor voltage U _scarrive the pre-control value U of the upper limit _{sc_up}or the pre-control value U of lower limit _{sc_down}time, make super-capacitor voltage U by the adjustment of the first batteries and the second batteries _scwithin being returned to upper lower limit value; Wherein, U _{sc_min}<U _{sc_down}<U _sc<U _{sc_up}<U _{sc_max}, U _{sc_min}for super-capacitor voltage lower limit, U _scfor super-capacitor voltage value, U _{sc_max}for super-capacitor voltage higher limit.Mixed energy storage system energy control method as shown in Figure 4.

In the diagram, after being regulated by the first batteries and the second batteries, super-capacitor voltage recovery value is designated as U _{sc_ref}, the discharge and recharge rated power of the first batteries and the second batteries is designated as P _cbat, P _dbat, as shown in Figure 4:

(1) U is worked as _sc≤ U _{sc_down}, super-capacitor voltage reaches the pre-control value of lower limit, now m=1, and charging accumulator group does not work, and electric discharge batteries is with rated power P _dbatsend power, until super-capacitor voltage returns to set point U _{sc_ref};

(2) U is worked as _sc>=U _{sc_up}, super-capacitor voltage reaches the pre-control value of the upper limit, now m=3, and electric discharge batteries does not work, and charging accumulator group is with rated power P _cbatabsorbed power, until super-capacitor voltage returns to set point U _{sc_ref};

(3) U is worked as _{sc_down}<U _sc<U _{sc_up}, super-capacitor voltage is in normal range (NR), and the power carrying out intermittent power supply by super capacitor is separately stabilized, now m=2, and charging accumulator group and electric discharge batteries all do not work.

Batteries is divided into the independent charging accumulator group controlled and electric discharge batteries under the condition that capacity is constant, batteries discharge and recharge number of times can be reduced to greatest extent.K ₁, k ₂represent the state of two group storage battery groupings respectively, k ₁=1, k ₂=0, represent that the first batteries is charging accumulator group, the second batteries is electric discharge batteries, k ₁=0, k ₂=1, represent that the first batteries is for electric discharge batteries, the second batteries is charging accumulator group.For making full use of the capacity of each self-contained storage battery group, prevent the discharge and recharge of the batteries degree of depth, the batteries based on state-of-charge mutually adjusts rule as shown in Figure 5.

In Figure 5, the state-of-charge lower limit of the first batteries and the second batteries is designated as SOC _up, the state-of-charge upper limit of the first batteries and the second batteries is designated as SOC _down, the state-of-charge of charging accumulator group is designated as SOC _cbat, the state-of-charge of electric discharge batteries is designated as SOC _dbat, be specially:

(1) SOC is worked as _cbat≤ SOC _upand SOC _dbat>=SOC _downtime, charging accumulator group, electric discharge batteries do not adjust, and carry out separately independently charge and discharge control, to maintain super-capacitor voltage in normal range (NR) according to super-capacitor voltage size;

(2) SOC is worked as _cbat>SOC _upor SOC _dbat<SOC _downtime, show that charging accumulator group reaches charging adjustment state or electric discharge batteries reaches electric discharge adjustment state, now charging accumulator group and electric discharge batteries are mutually adjusted, to avoid the discharge and recharge of the batteries degree of depth, make the capacity of batteries utilize optimization simultaneously.

For verifying validity of the present invention, making below in conjunction with example and illustrating.

Simulation model is as shown in Figure 1 built in MATLAB/Simulink.Major parameter is as follows: intermittent DG ideal voltage source is simulated, and output power range 21.5 ~ 69kW, mean value is about 45kW.The maximum charge-discharge electric power P of super capacitor _{sc_max}=25kW, U _{sc_min}=300V, U _{sc_max}=450V, U _{sc_down}=330V, U _{sc_up}=420V, U _{sc_ref}=370V, R ₃=0.1 Ω.The specified charge-discharge electric power P of batteries _cbat=P _dbat=15kW, rated voltage E ₁=E ₂=400V, internal resistance R ₁=R ₂=0.5 Ω, SOC _down=0.2, SOC _up=0.8.

T is not less than with the maximum power output duration according to super capacitor _scdetermine that its capacitance is C:

$C=\frac{{2P}_{\mathrm{sc}\_\max }{t}_{\mathrm{sc}}}{U_{\mathrm{sc}\_\mathrm{up}}^2-U_{\mathrm{sc}\_\mathrm{down}}^2}$

According to batteries with rated power P _dbatoutput duration is not less than t _batdetermine that its capacity is S:

S＝P _dbatt _bat

This case for reducing simulation time, gets t while the validity of checking institute extracting method _sc=3s, t _bat=180s, can obtain C=2F, S=0.75kWh, then the capacity of each independent batteries controlled is 0.375kWh.

The power curve of intermittent DG is as shown in Fig. 6 (a), the power fluctuation part of hybrid energy-storing control method to DG described in this case is adopted to stabilize, hybrid energy-storing power curve is as shown in Fig. 6 (b), stabilize rear DG and inject the power of electrical network as shown in Fig. 6 (c), known grid-connected power smooth, maintain mean value about 45kW, the power fluctuation of hybrid energy-storing to DG serves good stabilizes effect.

The above is only the preferred embodiment of the present invention; be noted that for those skilled in the art; under the premise without departing from the principles of the invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (6)

1. stabilize the hybrid energy-storing control method of intermittent power fluctuation for one kind, it is characterized in that: form hybrid energy-storing by batteries and super capacitor, batteries is divided into independent two the storage battery groupings controlled, the grouping of each group storage battery includes more than one storage battery, two group storage batteries is called the first batteries and the second batteries; Super capacitor, the first batteries and the second batteries are connected on the DC bus of hybrid energy-storing by two-way DC/DC converter respectively, realize the double-direction control of super capacitor, the first batteries and the second batteries; The DC bus of hybrid energy-storing is connected on public electric wire net by DC/AC converter, and intermittent power supply is connected on public electric wire net by DC/AC converter; The target stabilizing the power fluctuation of intermittent power supply be utilize hybrid energy-storing absorb intermittent power supply exert oneself in wave portion, make intermittent power grid power smooth; Batteries adopts the batteries based on state-of-charge to mutually adjust rule and realizes state control, is specially:

Using the first batteries as charging accumulator group, using the second batteries as electric discharge batteries, storage battery in charging accumulator group is in charged state or charging complete state, and the storage battery in electric discharge batteries is in discharge condition or waits for discharge condition; Prescribe a time limit under the state-of-charge of the part or all of storage battery in electric discharge batteries arrives state-of-charge, regulate this part or all of storage battery to charging accumulator group, the part or all of storage battery reaching the state-of-charge upper limit in charging accumulator group is adjusted to electric discharge batteries simultaneously, redistribute charging accumulator group and electric discharge batteries, form the first new batteries and the second batteries; In electric discharge batteries, some storage batterys that variety of priority driven carrying capacity is minimum or the overall mode exported with rated power of electric discharge batteries regulate super-capacitor voltage within nominal working range; In charging accumulator group, some storage batterys that variety of priority driven carrying capacity is maximum or charging accumulator group entirety enter electric discharge batteries.

2. the hybrid energy-storing control method stabilizing the fluctuation of intermittent power according to claim 1, it is characterized in that: the two-way DC/DC converter be connected with super capacitor adopts the Double-loop Control Strategy of outer voltage, current inner loop, the two-way DC/DC converter be connected with storage battery to adopt the control strategy of power outer shroud, current inner loop.

3. the hybrid energy-storing control method stabilizing the fluctuation of intermittent power according to claim 1, it is characterized in that: the target stabilizing the power fluctuation of intermittent power supply be utilize hybrid energy-storing absorb intermittent power supply exert oneself in wave portion, make intermittent power grid power smooth, be specially:

P _s＝P _g+P _h

Wherein, P _gfor intermittent power supply is exerted oneself, P _hfor hybrid energy-storing stabilizes power, P _sfor stabilizing rear intermittent power grid power; Exert oneself intermittent power supply P _gdeduct the level and smooth component obtained through low-pass filtering to be hybrid energy-storing and to stabilize power P _h, transfer function is:

$P_h\left(s\right)=-\frac{T_{g}s}{1+T_{g}s}{P}_g\left(s\right)$

Wherein, T _gfor time constant filter.

4. the hybrid energy-storing control method stabilizing the fluctuation of intermittent power according to claim 1, is characterized in that: hybrid energy-storing AC DC/AC converter adopts PQ control mode to export P _hto stabilize the power fluctuation of intermittent power supply, super capacitor, the first batteries and the second batteries carry out Power Exchange by the DC bus of two-way DC/DC converter and hybrid energy-storing, use mixed energy storage system energy control method to control super-capacitor voltage within limit value; In order to control super-capacitor voltage within upper lower limit value, i.e. U _{sc_min}<U _sc<U _{sc_max}, as super-capacitor voltage U _scarrive the pre-control value U of the upper limit _{sc_up}or the pre-control value U of lower limit _{sc_down}time, make super-capacitor voltage U by the adjustment of the first batteries and the second batteries _scwithin being returned to upper lower limit value; Wherein, U _{sc_min}<U _{sc_down}<U _sc<U _{sc_up}<U _{sc_max}, U _{sc_min}for super-capacitor voltage lower limit, U _scfor super-capacitor voltage value, U _{sc_max}for super-capacitor voltage higher limit.

5. the hybrid energy-storing control method stabilizing the fluctuation of intermittent power according to claim 4, is characterized in that: after being regulated by the first batteries and the second batteries, super-capacitor voltage recovery value is designated as U _{sc_ref}, the discharge and recharge rated power of the first batteries and the second batteries is designated as P _cbat, P _dbat, mixed energy storage system energy control method is specially:

(1) U is worked as _sc≤ U _{sc_down}, super-capacitor voltage reaches the pre-control value of lower limit, now m=1, and charging accumulator group does not work, and electric discharge batteries is with rated power P _dbatsend power, until super-capacitor voltage returns to set point U _{sc_ref};

(2) U is worked as _sc>=U _{sc_up}, super-capacitor voltage reaches the pre-control value of the upper limit, now m=3, and electric discharge batteries does not work, and charging accumulator group is with rated power P _cbatabsorbed power, until super-capacitor voltage returns to set point U _{sc_ref};

(3) U is worked as _{sc_down}<U _sc<U _{sc_up}, super-capacitor voltage is in normal range (NR), and the power carrying out intermittent power supply by super capacitor is separately stabilized, now m=2, and charging accumulator group and electric discharge batteries all do not work.

6. the hybrid energy-storing control method stabilizing the fluctuation of intermittent power according to claim 4, is characterized in that: the state-of-charge lower limit of the first batteries and the second batteries is designated as SOC _up, the state-of-charge upper limit of the first batteries and the second batteries is designated as SOC _down, the state-of-charge of charging accumulator group is designated as SOC _cbat, the state-of-charge of electric discharge batteries is designated as SOC _dbat, the batteries based on state-of-charge is mutually adjusted rule and is specially:

(1) SOC is worked as _cbat≤ SOC _upand SOC _dbat>=SOC _downtime, charging accumulator group, electric discharge batteries do not adjust, and carry out separately independently charge and discharge control, to maintain super-capacitor voltage in normal range (NR) according to super-capacitor voltage size;

(2) SOC is worked as _cbat>SOC _upor SOC _dbat<SOC _downtime, show that charging accumulator group reaches charging adjustment state or electric discharge batteries reaches electric discharge adjustment state, now charging accumulator group and electric discharge batteries are mutually adjusted, to avoid the discharge and recharge of the batteries degree of depth, make the capacity of batteries utilize optimization simultaneously.