CN104467031A - Reactive power allocating method for battery energy storage power station - Google Patents

Abstract

The invention discloses a reactive power allocating method for a battery energy storage power station. Units are classified according to real-time active power of all units in the battery energy storage power station, the maximum output reactive power values of all the units are calculated in a classified mode according to the reactive power dispatching instruction values and the classification result, and the reactive power allocation is carried out on all the units in the whole battery energy storage power station. By means of the real-time working state of the energy storage units in the battery energy storage power station, the reactive power allocation of the battery energy storage power station can be safely, stably and conveniently achieved, and the technical effects of reactive power responding and energy storage equipment service life prolonging are achieved.

Description

The reactive power distribution method of battery energy storage power station

Technical field

The invention belongs to battery energy storage power station technical field, more specifically say, relate to a kind of reactive power distribution method of battery energy storage power station.

Background technology

In the last few years, in succession carried out the Demonstration Application of various battery energy storage power station both at home and abroad and be incorporated into the power networks.Theory and practice proves, the introducing of scale battery energy storage power station can improve intermittent new energy power supply runnability and ability of regulation and control effectively, contributes to strengthening electrical network access capability.Can predict, scale energy storage and on a small scale distributed battery energy-accumulating power station proportion in power distribution network from now on will constantly increase, and produce actively impact to following power network development.

Along with the development of battery and integrated technology thereof, the application model of large-scale distributed and centralized battery energy storage power station progressively becomes a kind of preferred version.Several Large Copacity energy-storage batteries conventional at present in battery energy storage power station have the types such as sodium-sulphur battery, flow battery and lithium battery.

One of critical function of battery energy storage power station provides reactive power by energy accumulation current converter.After battery energy storage power station is incorporated to power distribution network on a large scale, how to distribute at the inner real-time optimization carrying out reactive power of scale battery energy storage power station is the key issue needing to solve.But the patent, document, technical report etc. of the reactive power distribution aspect of batteiy energy-accumulating power station are considerably less at present, need further investigation and explore.

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art, a kind of reactive power distribution method of battery energy storage power station is provided, in conjunction with the instantaneous operating conditions of energy storage unit each in battery energy storage power station, safety and stability, realize easily battery energy storage power station reactive power distribute.

For achieving the above object, the reactive power distribution method of battery energy storage power station of the present invention, comprises the following steps:

S1: the real-time active-power P of every platform unit at current control period t gathering battery energy storage power station _n, n represents unit sequence number, and span is n=1,2 ..., N, N represent the quantity of unit, according to real-time active-power P _nclassify to unit, sorting technique is:

A, work as P _n≠ 0, using n-th unit as " meritorious unit ", be defined as the 1st class;

B, work as P _n=0, using n-th unit as " idle unit ", be defined as the 2nd class;

S2: according to reactive power dispatch command value Q _sETTwith the classification results of step S1, calculate the maximum output reactive power value of every platform unit;

S3: according to reactive power dispatch command value Q _sETTwith the maximum output reactive power value of every platform unit, reactive power distribution is carried out to the every platform unit in whole battery energy storage power station.

Further, in step S2, the computational methods of maximum output reactive power value are:

The maximum reactive power value Q of A, the 1st class i-th unit _{i_1}ref (t+1) _maxfor:

$Q_{i\_1}\mathrm{ref}{(t+1)}_{\max }=\left\{\begin{array}{cc}\sqrt{S^2-P_{\mathrm{MAX}}^2,}& Q_{\mathrm{SETT}}\&GreaterEqual;0\\ -\sqrt{S^2-P_{\mathrm{MAX}}^2},& Q_{\mathrm{SETT}}<0\end{array}\right.$

Wherein, the span of i is i=1,2 ..., M ₁, M ₁represent the quantity of unit in the 1st class, S represents the apparent power value of unit, P _mAXrepresent the maximum discharge and recharge active power value of unit;

The maximum reactive power value Q of B, the 2nd class jth platform unit _{j_2}ref (t+1) _maxfor:

$Q_{j\_2}\mathrm{ref}{(t+1)}_{\max }=\left\{\begin{array}{cc}\mathrm{xS}& Q_{\mathrm{SETT}}\&GreaterEqual;0\\ -\mathrm{xS}& Q_{\mathrm{SETT}}<0\end{array}\right.$

Wherein, the span of j is j=1,2 ..., M ₂, M ₂represent the quantity of unit in the 2nd class, x represents the idle ratio of unit.

Further, the method that in step S3, reactive power is distributed is:

When | Q _sETT|≤M ₁× | Q _{i_1}ref (t+1) _max|| time, the idle output set point of every next control cycle of platform unit is:

$\begin{array}{c}{Q}_{i\_1}\mathrm{ref}(t+1)=\frac{Q_{\mathrm{SETT}}}{M_1}\\ Q_{j\_2}\mathrm{ref}(t+1)=0\end{array};$

Work as M ₁× | Q _{i_1}ref (t+1) _max|≤| Q _sETT|≤M ₂× | Q _{j_2}ref (t+1) _max| time, the idle output set point of every next control cycle of platform unit is:

Q _{i_1}ref(t+1)＝Q _{i_1}ref(t+1) _max

$Q_{j\_2}\mathrm{ref}(t+1)=\left\{\begin{array}{cc}{Q}_{j\_2}\mathrm{ref}{(t+1)}_{\max }& j<\mathrm{\&alpha;}\\ Q_{\mathrm{SETT}}-M_1\&times;Q_{i\_1}\mathrm{ref}{(t+1)}_{\max }-\mathrm{\&alpha;}\&times;Q_{j\_2}\mathrm{ref}{(t+1)}_{\max }& j=\mathrm{\&alpha;}+1\\ 0& \mathrm{\&alpha;}+1<j\&le;M_2\end{array}\right.$

Wherein, $\mathrm{\&alpha;}=\left[\frac{\left|Q_{\mathrm{SETT}}\right|-M_1\&times;\left|Q_{i\_1}\mathrm{ref}{(t+1)}_{\max }\right|}{\left|Q_{j\_2}\right|\mathrm{ref}{(t+1)}_{\max }}\right],$ [] expression rounds;

When | Q _sETT|>=M ₁× | Q _{i_1}ref (t+1) _max|+M ₂× | Q _{j_2}ref (t+1) _max| time, the idle output set point of every next control cycle of platform unit is:

$\begin{array}{c}{Q}_{i\_1}\mathrm{ref}(t+1)=Q_{i\_1}\mathrm{ref}{(t+1)}_{\max }\\ Q_{j\_2}\mathrm{ref}(t+1)=Q_{j\_2}\mathrm{ref}{(t+1)}_{\max }\end{array}.$

The reactive power distribution method of battery energy storage power station of the present invention, first according to the real-time active power of every platform unit of battery energy storage power station, unit is classified, then according to reactive power dispatch command value and classification results, the maximum output reactive power value of classified calculating every platform unit, carries out reactive power distribution to the every platform unit in whole battery energy storage power station.

Reactive power distribution method proposed by the invention, is easy to realize and grasp, can be realized the control objectives of the distribution of battery energy storage power station reactive power and running state monitoring by the method in practical engineering application.Compare with traditional reactive power mean allocation method; the present invention is by classifying to the unit of battery energy storage power station; the minimum start and stop number of times achieving unit improves battery energy storage power station resource utilization, has taken into account the technique effect of reactive power response and energy storage device raising in useful life.

Accompanying drawing explanation

Fig. 1 be the reactive power distribution method of battery energy storage power station of the present invention realize block diagram;

Fig. 2 is under static Active power mode, the reactive power distribution curve figure of battery energy storage power station;

Fig. 3 is under Fig. 2 example, the reactive power distribution curve figure of each unit adopting the present invention to obtain;

Fig. 4 is that the dynamic active power of battery energy storage power station unit exports;

Fig. 5 is under the dynamic active power pattern of Fig. 4, the reactive power distribution curve figure of energy-accumulating power station.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described, so that those skilled in the art understands the present invention better.Requiring particular attention is that, in the following description, when perhaps the detailed description of known function and design can desalinate main contents of the present invention, these are described in and will be left in the basket here.

Embodiment

Fig. 1 be the reactive power distribution method of battery energy storage power station of the present invention realize block diagram.As shown in Figure 1, the realization of the reactive power distribution method of battery energy storage power station of the present invention needs configuration machine component generic module and idle computing module, and its concrete steps comprise:

S1: every platform unit of computer-assisted classification module acquires battery energy storage power station is at the real-time active-power P of current control period t _n, n represents unit sequence number, and span is n=1,2 ..., N, N represent the quantity of unit, according to real-time active-power P _nclassify to unit, sorting technique is:

A, work as P _n≠ 0, namely n-th unit has the output of active power, using n-th unit as " meritorious unit ", is defined as the 1st class;

B, work as P _n=0, namely n-th unit without the output of active power using n-th unit as " idle unit ", be defined as the 2nd class.

S2: idle computing module is according to reactive power dispatch command value Q _sETTwith the classification results of step S1, calculate the idle capacity of every platform unit, i.e. maximum output reactive power value, circular is: first gather the apparent power value S of every platform unit, idle ratio x and maximum discharge and recharge active power value P _mAX, idle ratio x refers to that reactive power accounts for the ratio of gross power, and therefore its span is 0 < x < 1, and these three parameters are all configured by unit itself and determine, can not change because of using state.In the present invention, the unit in battery energy storage power station all adopts same model, and therefore these three parameters are all identical.Then the maximum output reactive power value of classified calculating belonging to unit:

A, " meritorious unit ": according to apparent power value and its maximum discharge and recharge active power value of current class unit, can calculate the maximum reactive power value that this " meritorious unit " can ensure to export.

The maximum reactive power value Q of the 1st class i-th unit _{i_1}ref (t+1) _maxfor:

$Q_{i\_1}\mathrm{ref}{(t+1)}_{\max }=\left\{\begin{array}{cc}\sqrt{{S_{i\_1}}^2-P_{\mathrm{MAX}\_i\_1}^2},& Q_{\mathrm{SETT}}\&GreaterEqual;0\\ -\sqrt{{S_{i\_1}}^2-P_{\mathrm{MAX}\_i\_1}^2},& Q_{\mathrm{SETT}}<0\end{array}\right.$

Wherein, the span of i is i=1,2 ..., M ₁, M ₁represent the quantity of unit in the 1st class.

When maximum reactive power value is timing, be maximum just idle fan-out capability, work as Q _{i_1}ref (t+1) _maxfor time negative, for time negative, it is maximum negative idle fan-out capability.

B, " idle unit ": because idle unit operation is in pure reactive power compensation state, so its reactive power maximum is the apparent power S of unit _{j_2}x _{j_2}doubly, that is:

The maximum reactive power value Q of the 2nd class jth platform unit _{j_2}ref (t+1) _maxfor:

$Q_{j\_2}\mathrm{ref}{(t+1)}_{\max }=\left\{\begin{array}{cc}\mathrm{xS}& Q_{\mathrm{SETT}}\&GreaterEqual;0\\ -\mathrm{xS}& Q_{\mathrm{SETT}}<0\end{array}\right.$

Wherein, the span of j is j=1,2 ..., M ₂, M ₂represent the quantity of unit in the 2nd class.

S3: according to reactive power dispatch command value Q _sETTwith the maximum output reactive power value of every platform unit, reactive power distribution is carried out to the every platform unit in whole battery energy storage power station.Specifically, be exactly according to reactive power dispatch command value Q _sETTsize, judge to need the unit that calls, then according to the maximum reactive power value that every class unit can export, set the idle output of every next control cycle of platform unit, its concrete grammar is:

The absolute value of the maximum output reactive power value of each unit is pressed classifiers selection, is then undertaken without the distribution of work by following three kinds of situations:

Situation 1: when | Q _sETT|≤M ₁× | Q _{i_1}ref (t+1) _max|| time, only need to call " meritorious unit " and just can meet the demands, do not need to call " idle unit ", the idle output set point of so every next control cycle of platform unit is:

$\begin{array}{c}{Q}_{i\_1}\mathrm{ref}(t+1)=\frac{Q_{\mathrm{SETT}}}{M_1}\\ Q_{j\_2}\mathrm{ref}(t+1)=0\end{array}$

Visible, in situation 1, the unit of each " meritorious unit " class shares out equally reactive power.

Situation 2: work as M ₁× | Q _{i_1}ref (t+1) _max|≤| Q _sETT|≤M ₂× | Q _{j_2}ref (t+1) _max| time, call " meritorious unit " and part " leave unused unit " and just can meet the demands, the idle output set point of every next control cycle of platform unit is:

Q _{i_1}ref(t+1)＝Q _{i_1}ref(t+1) _max

$Q_{j\_2}\mathrm{ref}(t+1)=\left\{\begin{array}{cc}{Q}_{j\_2}\mathrm{ref}{(t+1)}_{\max }& j<\mathrm{\&alpha;}\\ Q_{\mathrm{SETT}}-M_1\&times;Q_{i\_1}\mathrm{ref}{(t+1)}_{\max }-\mathrm{\&alpha;}\&times;Q_{j\_2}\mathrm{ref}{(t+1)}_{\max }& j=\mathrm{\&alpha;}+1\\ 0& \mathrm{\&alpha;}+1<j\&le;M_2\end{array}\right.$

Wherein, [] expression rounds.Visible, at least want α platform " idle unit " to export by maximum output reactive power value, then use one " idle unit " to supplement the reactive power demand of vacancy, other " idle unit " is never called.

Situation 3: when | Q _sETT|>=M ₁× | Q _{i_1}ref (t+1) _max|+M ₂× | Q _{j_2}ref (t+1) _max| time, all call " meritorious unit " and " leave unused unit " can not meet reactive power requirement completely, now " meritorious unit " and " idle unit " is all by maximum idle fan-out capability output reactive power, and namely the idle output set point of every next control cycle of platform unit is:

$\begin{array}{c}{Q}_{i\_1}\mathrm{ref}(t+1)=Q_{i\_1}\mathrm{ref}{(t+1)}_{\max }\\ Q_{j\_2}\mathrm{ref}(t+1)=Q_{j\_2}\mathrm{ref}{(t+1)}_{\max }\end{array}.$

Visible, the present invention, when carrying out concrete reactive power and distributing, adopts minimum unit to follow the tracks of to complete total reactive power as far as possible, can reduce the start-stop time of unit, thus extend unit durability.

In order to beneficial effect of the present invention is described, simulating, verifying is carried out to the reactive power distribution method that the present invention proposes.

Fig. 2 is under static Active power mode, the reactive power distribution curve figure of battery energy storage power station.As shown in Figure 2, under static Active power mode, namely the meritorious power given value of setting is a fixed value, adopt specific reactive power dispatch curve to verify the reactive power control method that the present invention proposes, this specific power dispatching curve by reactive power for just and rise, reactive power for just and transfinite, reactive power for just and decline, reactive power for negative and rise, reactive power is for negative and to transfinite and reactive power formed, to verify all kinds of energy storage machine group scheduling order of priority in Reactive Power Control strategy herein for negative and 6 stages that declined.

Fig. 3 is under Fig. 2 example, the reactive power distribution curve figure of each unit adopting the present invention to obtain.As shown in Figure 3, under static Active power mode, active power is set as 60kW, and active power realizes active power output by calling energy storage unit BESS1 ~ 4.Therefore, BESS1 ~ 4 are " meritorious unit ", and BESS5 ~ 10 are " idle unit ".Just be and ascent stage, when total reactive power is within the scope of the total idle fan-out capability of energy storage unit BESS1 ~ 4, adopt equalitarian distribution method priority scheduling " meritorious unit " to complete total reactive power and export at reactive power set-point; When total reactive power exceeds the total idle fan-out capability scope of energy storage unit BESS1 ~ 4, adopt the mode of minimum number of units to call energy storage unit BESS5 ~ 10 successively and complete total reactive power output.When reactive power set-point is greater than total reactive power fan-out capability of battery energy storage power station, each energy storage unit will export by its maximum idle fan-out capability.

Fig. 4 is that the dynamic active power of battery energy storage power station unit exports.As shown in Figure 4, the active power of battery energy storage power station unit is dynamic change.Fig. 5 is under Fig. 4 dynamic active power pattern, the reactive power distribution curve figure of energy-accumulating power station.As shown in Figure 5, under dynamic active power pattern, while active power change, by the reactive power dispatch command of given change, the reactive power investigating each unit of energy-accumulating power station is distributed and total reactive power tracking situation, verifies Reactive Power Control strategy validity in this paper.For explaining that the present invention controls in detail, access time, interval 1 ~ 5 was described.Table 1 is the reactive power value of all kinds of unit in time interval 1 ~ 5.

Table 1

In time interval 1, active power set-point is-18kW, completes total active power output by calling energy storage unit BESS9,10.Reactive power dispatch command value is 500kVar, by calling " meritorious unit " BSSE9,10 and " idle unit " BESS1 ~ 6 have 8 units altogether and complete total reactive power and follow the tracks of, wherein BESS9,10 and BESS1 ~ 5 all export with its maximum just idle power output, remaining reactive power vacancy 23.4kVar is exported by BESS6.

In time interval 2, active power set-point is 18kW, completes total active power output by calling energy storage unit BESS1,2.Reactive power dispatch command value is 200kVar, by calling " meritorious unit " BESS1,2 and idle B of Unit ESS3 ~ 4 have 4 units altogether and complete total reactive power and follow the tracks of, wherein BESS1,2 and BESS3 all export with its maximum just idle power output, remaining reactive power vacancy 31.4kVar is exported by BESS4;

In time interval 3, active power set-point is 0, and now all energy storage units are idle unit.Reactive power dispatch command value is-800kVar, exceedes the maximum negative idle power output that all energy storage units are total, and therefore all units all export with its maximum negative idle power output;

In time interval 4, energy storage unit BESS1 ~ 8 are all in maximum state of charge, and energy storage unit BESS9,10 is in stopped status.Reactive power dispatch command value is-500kVar, " meritorious unit " BESS1 ~ 8 and idle B of Unit ESS9 ~ 10 have 10 units altogether and complete total reactive power and follow the tracks of by calling, wherein BESS1 ~ 9 all export with its maximum just idle power output, and remaining reactive power vacancy-56.6kVar is exported by BESS10;

In time interval 5, energy storage unit BESS3 ~ 10 are all in maximum discharge condition, and energy storage unit BESS1,2 is in stopped status.Reactive power dispatch command value is-500kVar, " meritorious unit " BESS3 ~ 10 and idle B of Unit ESS1 ~ 2 have 10 units altogether and complete total reactive power and follow the tracks of by calling, wherein BESS1 and BESS3 ~ 10 all export with its maximum just idle power output, and remaining reactive power vacancy-56.6kVar is exported by BESS2.

Although be described the illustrative embodiment of the present invention above; so that those skilled in the art understand the present invention; but should be clear; the invention is not restricted to the scope of embodiment; to those skilled in the art; as long as various change to limit and in the spirit and scope of the present invention determined, these changes are apparent, and all innovation and creation utilizing the present invention to conceive are all at the row of protection in appended claim.

Claims (3)

1. a reactive power distribution method for battery energy storage power station, is characterized in that, comprise the following steps:

S1: the real-time active-power P of every platform unit at current control period t gathering battery energy storage power station _n, n represents unit sequence number, and span is n=1,2 ..., N, N represent the quantity of unit, according to real-time active-power P _nclassify to unit, sorting technique is:

A, work as P _n≠ 0, using n-th unit as " meritorious unit ", be defined as the 1st class;

B, work as P _n=0, using n-th unit as " idle unit ", be defined as the 2nd class;

S2: according to reactive power dispatch command value Q _sETTwith the classification results of step S1, calculate the maximum output reactive power value of every platform unit;

S3: according to reactive power dispatch command value Q _sETTwith the maximum output reactive power value of every platform unit, reactive power distribution is carried out to the every platform unit in whole battery energy storage power station.

2. reactive power distribution method according to claim 1, is characterized in that, in described step S3, the computational methods of maximum output reactive power value are:

The maximum reactive power value Q of A, the 1st class i-th unit _{i_1}ref (t+1) _maxfor:

$Q_{i\_1}\mathrm{ref}{(t+1)}_{\max }=\left\{\begin{array}{cc}\sqrt{S^2-P_{\mathrm{MAL}}^2},& Q_{\mathrm{SETT}}\&GreaterEqual;0\\ -\sqrt{S^2-P_{\mathrm{MAX}}^2},& Q_{\mathrm{SETT}}<0\end{array}\right.$

Wherein, the span of i is i=1,2 ..., M ₁, M ₁represent the quantity of unit in the 1st class, S represents the apparent power value of unit, P _mAXrepresent the maximum discharge and recharge active power value of unit;

The maximum reactive power value Q of B, the 1st class jth platform unit _{j_2}ref (t+1) _maxfor:

$Q_{j\_2}\mathrm{ref}{(t+1)}_{\max }=\left\{\begin{array}{cc}\mathrm{xS}& Q_{\mathrm{SETT}}\&GreaterEqual;0\\ -\mathrm{xS}& Q_{\mathrm{SETT}}<0\end{array}\right.$

Wherein, the span of j is j=1,2 ..., M ₂, M ₂represent the quantity of unit in the 2nd class, x represents the idle ratio of unit.

3. reactive power distribution method according to claim 1, is characterized in that, in described step S4 without the method for the distribution of work is:

When | Q _sETT|≤M ₁× | Q _{i_1}ref (t+1) _max|| time, the idle output set point of every next control cycle of platform unit is:

$Q_{i\_1}\mathrm{ref}(t+1)=\frac{Q_{\mathrm{SETT}}}{M_1};$

Q _{j_2}ref(t+1)＝0

Work as M ₁× | Q _{i_1}ref (t+1) _max|≤| Q _sETT|≤M ₂× | Q _{j_2}ref (t+1) _max| time, the idle output set point of every next control cycle of platform unit is:

Q _{i_1}ref(t+1)＝Q _{i_1}ref(t+1) _max

$Q_{j\_2}\mathrm{ref}(t+1)=\left\{\begin{array}{cc}{Q}_{j\_2}\mathrm{ref}{(t+1)}_{\max }& j\&le;\mathrm{\&alpha;}\\ Q_{\mathrm{SETT}}-M_1\&times;Q_{i\_1}\mathrm{ref}{(t+1)}_{\max }-\mathrm{\&alpha;}\&times;Q_{j\_2}\mathrm{ref}{(t+1)}_{\max }& j=\mathrm{\&alpha;}+1\\ 0& \mathrm{\&alpha;}+1<j\&le;M_2\end{array}\right.$

Wherein, $\mathrm{\&alpha;}=\left[\frac{\left|Q_{\mathrm{SETT}}\right|-M_1\&times;\left|Q_{i\_1}\mathrm{ref}{(t+1)}_{\max }\right|}{\left|Q_{j\_2}\mathrm{ref}{(t+1)}_{\max }\right|}\right],$ [] expression rounds;

When | Q _sETT|>=M ₁× | Q _{i_1}ref (t+1) _max|+M ₂× | Q _{j_2}ref (t+1) _max| time, the idle output set point of every next control cycle of platform unit is:

Q _{i_1}ref(t+1)＝Q _{i_1}ref(t+1) _max

Q _{j_2}ref(t+1)＝Q _{j_2}ref(t+1) _max。