CN102244390B - Smooth energy storage system capacity optimization method for microgrid junctor power fluctuation - Google Patents

Abstract

The invention provides a smooth energy storage system capacity optimization method for microgrid junctor power fluctuation, comprising the following steps: 1) determining reasonable output power of renewable energy sources and load sample data, wherein the power output of the renewable energy sources and the sampling period of load samples take values which are more than or equal to1 minute and less than or equal to 1 hour, and the power output of the renewable energy sources and the load sample data comprise the sampling period or sampling frequency, the sampling start-stop time and the sampling length; 2) using a simulation method to determine the power of the energy storage system in accordance with the output power of the renewable energy sources and the load sample data; and 3) using the simulation method to determine the capacity of and the initial SOC state in accordance with the power output required by the energy storage system. A reasonable energy storage system capacity optimization scheme which can meet a junctor power control target, an internal electric source of the microgrid and the running constraints of the energy storage system is practical, simple and quick and is easy to realize. The method provided by the invention has wide application prospects in capacity planning, design and optimization of the energy storage system in the microgrid with high renewable energy resource permeability.

Description

The energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation

Technical field

The present invention relates to a kind of method of energy storage system capacity planning, design and optimization in microgrid, particularly relate to a kind of energy storage system capacity optimization method of controlling the level and smooth microgrid interconnection tie power fluctuation of target and net load (load deducts the regenerative resource power stage) output sum result of spectrum analysis based on interconnection power.

Background technology

The regenerative resource that wind-force, photovoltaic generation is representative of take has intermittence, randomness and the characteristics such as uncertain.Along with the regenerative resource permeability constantly increases, they have brought increasing challenge to the safe and reliable operation of electrical network.Microgrid is combined regenerative resource power supply system, load, controllable electric power, energy-storage system etc., by limited public contact point (being generally 1), with electrical network, is connected, and effective technological approaches is provided for the high permeability regenerative resource is grid-connected.Energy-storage system relies on it can fill the operation characteristic that can put, can effectively overcome the fluctuation of renewable energy system in microgrid, improves microgrid " close friend " degree to electrical network.

The microgrid internal electric source, by whether controlled, can be divided into uncontrollable power supply and controllable electric power; The former take wind-force, photovoltaic generation etc. is representative, and it is representative that the latter be take miniature gas turbine (MT), diesel engine generator, fuel cell etc.Energy-storage system coordinates the microgrid internal electric source, microgrid and external electrical network interconnection power can be controlled near steady state value, to offset the adverse effect of high regenerative resource permeability to electrical network.The factor that energy storage system capacity optimization method under the scene of regenerative resource permeability microgrid interconnection power control is at present considered is not comprehensive, so definite method of relevant energy storage system capacity is deep not enough, does not reach practical.

Summary of the invention

Technical problem to be solved by this invention is, provide a kind of can effectively providing to meet interconnection power and control target, microgrid internal electric source, the lower energy-storage system optimizing capacity scheme of energy-storage system operation constraint, practical, simple, fast and be easy to the energy storage system capacity optimization method of the level and smooth microgrid interconnection tie power fluctuation of realization.

The technical solution adopted in the present invention is: a kind of energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation includes following steps:

1) determine rational regenerative resource power output and load sample data, wherein, regenerative resource power stage and load sample sampling period get and are more than or equal to 1 minute, be less than or equal to a numerical value of 1 hour, described regenerative resource power stage and load sample data comprise sampling period or sample frequency, sampling beginning and ending time, sampling length;

2), according to regenerative resource power output and load sample data, utilize simulation method to determine energy-storage system power;

3), according to the output of energy-storage system power demand, utilize simulation method to obtain and determine capacity and initial SOC state.

2. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 1, is characterized in that, the described simulation method of utilizing is determined energy-storage system power, comprises the steps:

(1) determine the required controlled power output of microgrid P _ned, and it is carried out to discrete Fourier transform;

(2) based on the required controlled power output of microgrid P _nedresult of spectrum analysis, determine that meet microgrid interconnection power controls target P _tLfrequency domain scope and the time domain power stage corresponding to the required compensation frequency domain of this controllable electric power scope of the required compensation of controllable electric power of constraint;

(3) according to the ideal value of controllable electric power power stage, under the impact of considering energy-storage system efficiency for charge-discharge factor, determine the energy-storage system power stage can guarantee the energy-storage system continuous and steady operation, and then the required maximum of definite energy-storage system discharges and recharges power, that is its rated power.

3. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 2, is characterized in that, the required controlled power output of described definite microgrid P _ned, and it is carried out to discrete Fourier transform, specifically:

Set microgrid by batch (-type) regenerative resource, controllable electric power, energy-storage system and load structure, corresponding output is respectively by column vector P _gr, P _gc, P _eS0and P _lmean, for meeting microgrid interconnection power, control target P _tLdemand has following power constraint:

P _gr-P _L+P _ES0+P _gc＝P _TL

P _gr[n]-P _L[n]+P _ES0[n]+P _gc[n]＝P _TL[n] (1)

n∈{1，...，N _s}

In formula, P _*[n] represents column vector P _*in n element, i.e. n the power output [kW] that sampled point is corresponding, N _srepresent the sampled point number, the span of n is the same; P _*the sample frequency of the sampled data of representative, sampled point number and sampling beginning and ending time are all identical, make f _s, T _sbe respectively sample data P _*sample frequency [Hz] and sampling period [s]; P _eS0[n] can just can bear, and for just representing energy storage system discharges, is negative representative charging; P _tL[n] also can just can bear, and for just representing that microgrid is to the electrical network power output, for negative, represents that electrical network is to the microgrid injecting power;

Load is deducted to the regenerative resource power stage and be defined as net load P _lnet, that is:

P _Lnet＝P _L-P _gr (2)

Control target P at known microgrid interconnection power _tLafter, can determine the required controlled power output of microgrid sum P by formula (1), (2) _ned:

P _end＝P _TL+P _Lnet＝P _ES0+P _gc (3)

Formula (3) shows the required controlled power output of microgrid P _nedcontrol target and net load decision by microgrid interconnection power, provided by energy-storage system and controllable electric power.

To required controlled power output P in microgrid _nedcarry out spectrum analysis, obtain amplitude-frequency S as a result _nedand f _ned.

S _ned＝DFT(P _ned)＝[S _ned[1]，..，S _ned[n]，...，S _ned[N _s]] ^T (4)

f _ned＝[f _ned[1]，...，f _ned[n]，...，f _ned[N _s]] ^T

DFT (P _ned) represent sample data P _nedcarry out discrete Fourier transform.S _ned[n]=R _ned[n]+I _ned[n] i represents n frequency f in the Fourier transform result _nedthe amplitude that [n] is corresponding, R _ned[n], I _ned[n] is respectively for real part and the imaginary part of amplitude.F _nedfor with S _nedcorresponding column of frequencies vector.

4. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 2, is characterized in that, described based on the required controlled power output of microgrid P _nedresult of spectrum analysis, determine that meet microgrid interconnection power controls target P _tLfrequency domain scope and the time domain power stage corresponding to the required compensation frequency domain of this controllable electric power scope of the required compensation of controllable electric power of constraint, specifically:

Set f _gcthe compensation frequency range of controllable electric power is determined in representative according to result of spectrum analysis; S _gcrepresenting that controllable electric power is required provides the result of spectrum analysis that power stage is corresponding,

$S_{\mathrm{gc}}\left[n\right]=\left\{\begin{array}{cc}{S}_{\mathrm{ned}}\left[n\right]& f_{\mathrm{gc}}\&Element;{\mathrm{<figure-callout\; id="0"\; label="f\; gc"\; filenames="HDA0000075016470000011.png,HDA0000075016470000021.png"\; state="\{\{state\}\}">f</figure-callout>}}_{\mathrm{gc}}\\ 0+0i& f_{\mathrm{gc}}\&NotElement;f_{\mathrm{gc}}\end{array}\right.---\left(5\right)$

To S _gccarry out the discrete fourier inverse transformation the required controlled power Output rusults P that provides of controllable electric power is provided _gc:

P _gc＝IDFT(S _gc)＝[P _gc[1]，...，P _gc[n]，...，P _gc[N _s]] ^T (6)

In formula, IDFT (S _gc) represent S _gccarry out the discrete fourier inverse transformation;

Setting the inner controllable electric power power stage of microgrid is:

$P_{\mathrm{gc}}\left[n\right]=\underset{j=1}{\overset{N_{\mathrm{gc}}}{\mathrm{\&Sigma;}}}{P}_{\mathrm{gc},j}\left[n\right]---\left(7\right)$

In formula, N _gcrepresent that controllable electric power is by N _gcindividual electric power generating composition of the same type; J=1 ..., N _gcrepresent of the same type in j controllable electric power.P _{gc, j}[n] represented in corresponding n the sampling period, controllable electric power j power output size;

For guaranteeing operational efficiency and extending unit durability, controllable electric power power stage P _{gc, j}[n] needs to meet following constraint:

$u_{\mathrm{gc},j}\left[n\right]P_{\mathrm{gc},j}^{\min }\&le;P_{\mathrm{gc},j}\left[n\right]\&le;u_{\mathrm{gc},j}\left[n\right]P_{\mathrm{gc},j}^{\max }---\left(8\right)$

In formula, u _{gc, j}[n], for controllable electric power operation sign, gets 0 or 1; Get 0 o'clock, representative is n sampling period, and controllable electric power j is operation not; Get the representative operation at 1 o'clock;

minimum while representing respectively controllable electric power j operation, maximum power output, cause decrease in efficiency and shortened equipment life for avoiding too low power stage,

get the rated power of 0.3 times;

get the rated power of 1 times;

From formula (7), (8), controllable electric power power output sum P in microgrid _gcneed to meet following constraint:

$\underset{j=1}{\overset{N_{\mathrm{gc}}}{\mathrm{\&Sigma;}}}{u}_{\mathrm{gc},j}{P}_{\mathrm{gc},j}^{\min }\&le;P_{\mathrm{gc}}\left[n\right]\&le;\underset{j=1}{\overset{N_{\mathrm{gc}}}{\mathrm{\&Sigma;}}}{u}_{\mathrm{gc},j}{P}_{\mathrm{gc},j}^{\max }---\left(9\right)$

$\min \left\{P_{\mathrm{gc},j}^{\min }\right\}\&le;P_{\mathrm{gc}}\left[n\right]\&le;\underset{j=1}{\overset{N_{\mathrm{gc}}}{\mathrm{\&Sigma;}}}{P}_{\mathrm{gc},j}^{\max },$ P _gc[n]＞0 (10)

Determine the output of controllable electric power ideal power, at first will select rational controllable electric power frequency domain compensation scope f _gcadopt try and error method, from DC component, gradually frequency range is extended to high band, utilize the controllable electric power power stage corresponding to analytical method check different compensation frequency range of front whether to meet formula (10), and then determine and can meet controllable electric power power output constraint, can guarantee again the controllable electric power compensation frequency range that energy storage system capacity is as far as possible little, and then obtain the idealized power stage of controllable electric power.

5. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 2, is characterized in that, described energy-storage system power stage, and energy-storage system rated power definite:

According to controllable electric power ideal power output P _gc, the energy-storage system power demand is exported by column vector P _eS0=[P _eS0[1] ..., P _eS0[n] ..., P _eS0[N _s]] ^tmean:

P _ES0[n]＝P _ned[n]-P _gc[n] (11)

Energy-storage system overall efficiency η _eSmean, the actual power that discharges and recharges of energy-storage system, use P _eS=[P _eS[1] ..., P _eS[n] ..., P _eS[N _s] ^tmean:

$P_{\mathrm{ES}}\left[n\right]=\left\{\begin{array}{cc}{P}_{\mathrm{ES}0}\left[n\right]/{\mathrm{\&eta;}}_{\mathrm{ES},d}& P_{\mathrm{ES}0}\left[n\right]\&GreaterEqual;0\\ P_{\mathrm{ES}0}\left[n\right]{\mathrm{g\&eta;}}_{\mathrm{ES},c}& P_{\mathrm{ES}0}\left[n\right]<0\end{array}\right.---\left(12\right)$

In formula, η _{eS, c}and η _{eS, d}represent respectively energy-storage system charge efficiency and discharging efficiency;

In whole sample cycle, for guaranteeing the energy-storage system continuous and steady operation, needing to meet clean charge/discharge electric weight in the energy-storage system running, be zero, that is:

$\mathrm{\&Delta;E}=\underset{n=1}{\overset{\mathrm{Ns}}{\mathrm{\&Sigma;}}}\left(P_{\mathrm{ES}}\right[n\left]\right)=0---\left(13\right).$

6. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 5, is characterized in that, for guaranteeing the output of system power target, meets:

$\mathrm{\&Delta;E}=\underset{n=1}{\overset{\mathrm{Ns}}{\mathrm{\&Sigma;}}}\left(P_{\mathrm{ES}}\right[n\left]\right)=0$

Microgrid interconnection power is controlled to target P _tLthe whole upwards translation of whole translation downwards or controllable electric power power stage realizes; The translational movement absolute value is designated as Δ P, by iterative computation, obtains; After translation, the energy-storage system power demand is output as:

P _ES0[n]＝P _ned[n]-ΔP-P _gc[n] (14)

Utilize formula $P_{\mathrm{ES}}\left[n\right]=\left\{\begin{array}{cc}{P}_{\mathrm{ES}0}\left[n\right]/{\mathrm{\&eta;}}_{\mathrm{ES},d}& P_{\mathrm{ES}0}\left[n\right]\&GreaterEqual;0\\ P_{\mathrm{ES}0}\left[n\right]{\mathrm{g\&eta;}}_{\mathrm{ES},0}& P_{\mathrm{ES}0}\left[n\right]<0\end{array}\right.$ Obtain the actual performance number that discharges and recharges of energy-storage system after consideration discharges and recharges power loss; In whole sample data in the cycle, the actual power P that discharges and recharges of the energy-storage system obtained _eSthe maximum of absolute value is the energy-storage system power-handling capability:

$P_{\mathrm{ES}}^n=\max \left\{\right|P_{\mathrm{ES}}\left[n\right]\left|\right\}---\left(15\right)$

7. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 1, is characterized in that, the described simulation method of utilizing obtains definite capacity and initial SOC state, comprises the steps:

(1) the energy-storage system real output data based on definite, add up the energy-storage system charge/discharge electricity amount of each sample point, obtains the energy hunting of different sampling instant energy-storage systems with respect to initial condition;

(2) for energy-storage system energy hunting in the cycle in whole sample data, calculate the poor of energy-storage system maximum, least energy, consider energy-storage system SOC restriction, obtain the capacity that energy-storage system should possess, that is energy-storage system rated capacity value;

(3), after determining energy storage system capacity, SOC is no more than restriction range when guaranteeing the energy-storage system operation, set the SOC initial value will be satisfied condition.

8. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 7, is characterized in that, the different sampling instant energy-storage systems of described acquisition, with respect to the energy hunting of initial condition, specifically adopt following formula:

$E_{\mathrm{ES},\mathrm{ac}}\left[m\right]=\underset{0}{\overset{m}{\mathrm{\&Sigma;}}}\left(P_{\mathrm{ES}}\right[m]g{T}_s/3600),$ m＝0，...，N _s (16)

In formula, T _s/ 3600 mean chronomere's " second " convert be chronomere " hour "; E _{eS, ac}[m] represents energy-storage system energy hunting with respect to initial condition m sampling instant, that is m the sampling period before corresponding, that is, from the 0th to m sampling period, energy-storage system accumulative total charge-discharge energy sum [kWh].

9. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 7, is characterized in that, describedly obtains the capacity that energy-storage system should possess, that is energy-storage system rated capacity value, specifically adopts following formula:

$E_{\mathrm{ES}}^n=\frac{\max \left\{E_{\mathrm{ES},\mathrm{ac}}\right[m\left]\right\}-\min \left\{E_{\mathrm{ES},\mathrm{ac}}\right[m\left]\right\}}{{\mathrm{SOC}}_{\max }-{\mathrm{SOC}}_{\min }}---\left(17\right)$

In formula, SOC _maxand SOC _minrepresent respectively the upper and lower limit constraint of SOC in the energy-storage system actual motion, max{E _{eS, ac}[m] }-min{E _{eS, ac}[m] } represented the absolute value of energy-storage system ceiling capacity fluctuation in the whole sample data cycle.

10. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 7, is characterized in that, described SOC initial value will satisfied condition be to adopt following formula to obtain:

$\mathrm{SOC}\left[m\right]=\mathrm{SOC}\left[n\right]-\frac{E_{\mathrm{ES},\mathrm{ac}}\left[m\right]}{E_{\mathrm{ES}}^n}---\left(18\right)$

In formula, SOC[0] represent the initial SOC value of energy-storage system;

If energy storage system capacity satisfies the demands, in the time of guaranteeing the energy-storage system operation, SOC is no more than restriction range, and the SOC initial value need to meet following initial value computing formula:

$\mathrm{SOC}\left[0\right]={\mathrm{SOC}}_{\min }+\frac{\max \left\{E_{\mathrm{ES},\mathrm{ac}}\right[m\left]\right\}}{E_{\mathrm{ES}}^n}={\mathrm{SOC}}_{\max }+\frac{\min \left\{E_{\mathrm{ES},\mathrm{ac}}\right[m\left]\right\}}{E_{\mathrm{ES}}^n}---\left(19\right)$

The energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation of the present invention, the result of spectrum analysis that the interconnection power of take is controlled target and net load (load deducts the regenerative resource power stage) output sum is basis, can consider the interconnection power target requirement after the energy-storage system compensation, controllable electric power output power limit in microgrid, the energy-storage system efficiency for charge-discharge, SOC operation restriction waits constraint, provide and reasonably can meet interconnection power control target, the microgrid internal electric source, energy-storage system optimizing capacity scheme under energy-storage system operation constraint, the method practicality, simply, fast and be easy to realize.Aspect energy storage system capacity planning in high regenerative resource permeability microgrid, Design and optimization, have broad application prospects and huge society, economic benefits.

The accompanying drawing explanation

Fig. 1 is the microgrid structural representation;

Fig. 2 is the output of microgrid photovoltaic, load, net load curve;

Fig. 3 is the required controlled power output of microgrid;

Fig. 4 is the required controlled power output spectrum of microgrid analysis result;

Fig. 5 is power stage constraint and the energy storage system capacity that different miniature combustion engine compensation cycle lower limits are corresponding

Wherein, (a) being the corresponding power stage upper limits of different MT compensation cycle lower limits, is (b) the corresponding desired volumes of the different energy-storage system compensation cycle upper limits;

Fig. 6 is optimum capacity program analysis result of calculation

Wherein, be (a) output of MG controlled power, (b) be the energy-storage system energy hunting.

Embodiment

Provide specific embodiment below in conjunction with accompanying drawing, how the energy storage system capacity optimization method that further illustrates level and smooth microgrid interconnection tie power fluctuation of the present invention is realized.

The energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation of the present invention, comprise the steps:

One, before determining energy storage system capacity, at first need to select rational regenerative resource power output and load sample data according to application scenarios.The sampling period of sample data (or sample frequency), sampling beginning and ending time, sampling length are directly relevant to the particular problem of intending research.Control scene for microgrid interconnection power, energy-storage system is mainly used in compensating the mismatch between the interior regenerative resource power stage of microgrid and workload demand, and its time yardstick is generally several minutes levels to 1 hour.That is, the sampling period gets and is more than or equal to 1 minute, is less than or equal to a numerical value of 1 hour.If the sampling period of load monitoring system is 5 minutes, the regenerative resource power stage specimen sample cycle also is chosen as 5 minutes.Certainly, if the specimen sample cycle, to be less than this numerical value better.Without loss of generality, for the capacity under this kind of application scenarios of energy-storage system, determine, it is 1 minute that the present invention selects regenerative resource power stage and load sample sampling period.

The length of sample data fragment selects to need the discharge capacity of energy-storage system in the As soon as possible Promising Policy fragment and charge volume (deduction discharges and recharges power loss) about equally.When meeting this necessary condition, when the primary power in the time of can guaranteeing the level and smooth microgrid interconnection tie power fluctuation of energy-storage system and end, energy equates substantially.Because operation of power networks generally be take 1 day as unit, therefore data slot length is chosen as 1 day.In addition, the regenerative resources such as photovoltaic, wind power generation have stronger seasonality, and data slot can be chosen typical case's day data of Various Seasonal (summer, winter).

After determining rational regenerative resource power output and load sample data, can determine successively energy-storage system power, capacity and initial SOC state.

Two, power determination

Control target requirement for meeting microgrid interconnection power, guarantee the energy-storage system continuous and steady operation, should guarantee that energy-storage system possesses enough large power definite rational energy-storage system power stages of discharging and recharging.For given regenerative resource power stage, load sample data, the required maximum of energy-storage system that meets interconnection power control goal constraint discharges and recharges power and can utilize simulation method to obtain.So-called simulation method consists of following several steps:

1) determine the required controlled power output of microgrid P _ned, and it is carried out to discrete Fourier transform.

Suppose that microgrid is by batch (-type) regenerative resource, controllable electric power, energy-storage system and load structure, corresponding output is respectively by column vector P _gr, P _gc, P _eS0and P _lmean.Control target P for meeting microgrid interconnection power _tLdemand has following power constraint:

P _gr-P _L+P _ES0+P _gc＝P _TL

P _gr[n]-P _L[n]+P _ES0[n]+P _gc[n]＝P _TL[n] (1)

n∈{1，...，N _s}

In formula, P _*[n] represents column vector P _*in n element, i.e. n the power output [kW] that sampled point is corresponding, N _srepresent the sampled point number.P _*the sample frequency of the sampled data of representative, sampled point number and sampling beginning and ending time are all identical, make f _s, T _sbe respectively sample data P _*sample frequency [Hz] and sampling period [s].P _eS0[n] can just can bear, and for just representing energy storage system discharges, is negative representative charging; P _tL[n] also can just can bear, and for just representing that microgrid is to the electrical network power output, for negative, represents that electrical network is to the microgrid injecting power.

Load is deducted to the regenerative resource power stage and be defined as net load P _lnet, that is:

P _Lnet＝P _L-P _gr (2)

Control target P at known microgrid interconnection power _tLafter, can determine the required controlled power output of microgrid sum P by formula (1), (2) _ned:

P _ned＝P _TL+P _Lnet＝P _ES0+P _gc (3)

Formula (3) shows the required controlled power output of microgrid P _nedcontrol target and net load decision by microgrid interconnection power, provided by energy-storage system and controllable electric power.

To required controlled power output P in microgrid _nedcarry out spectrum analysis, obtain amplitude-frequency S as a result _nedand f _ned.

S _ned＝DFT(P _ned)＝[S _ned[1]，...，S _ned[n]，...，S _ned[N _s]] ^T (4)

f _ned＝[f _ned[1]，...，f _ned[n]，...，f _ned[N _s]] ^T

DFT (P _ned) represent sample data P _nedcarry out discrete Fourier transform.S _ned[n]=R _ned[n]+I _ned[n] i represents n frequency f in the Fourier transform result _nedthe amplitude that [n] is corresponding, R _ned[n], I _ned[n] is respectively for real part and the imaginary part of amplitude.F _nedfor with S _nedcorresponding column of frequencies vector.

2) based on the required controlled power output of microgrid P _nedresult of spectrum analysis, can determine that meeting microgrid interconnection power controls target P _tLfrequency domain scope and the time domain power stage corresponding to the required compensation frequency domain of this controllable electric power scope of the required compensation of controllable electric power of constraint.

Suppose f _gcthe compensation frequency range of controllable electric power is determined in representative according to result of spectrum analysis; S _gcrepresenting that controllable electric power is required provides the result of spectrum analysis that power stage is corresponding.Wherein, compensate amplitude size corresponding to frequency range constant, the outer amplitude of compensation frequency range set to 0---mean that controllable electric power corresponding to its compensation frequency range provides at power stage.

$S_{\mathrm{gc}}\left[n\right]=\left\{\begin{array}{cc}{S}_{\mathrm{ned}}\left[n\right]& f_{\mathrm{gc}}\&Element;{\mathrm{<figure-callout\; id="0"\; label="f\; gc"\; filenames="HDA0000075016470000011.png,HDA0000075016470000021.png"\; state="\{\{state\}\}">f</figure-callout>}}_{\mathrm{gc}}\\ 0+0i& f_{\mathrm{gc}}\&NotElement;f_{\mathrm{gc}}\end{array}\right.---\left(5\right)$

To S _gccarry out the discrete fourier inverse transformation the required controlled power Output rusults P that provides of controllable electric power can be provided _gc:

P _gc＝IDFT(S _gc)＝[P _gc[1]，...，P _gc[n]，...，P _gc[N _s]] ^T (6)

In formula, IDFT (S _gc) represent S _gccarry out the discrete fourier inverse transformation.

The inner controllable electric power of microgrid generally by bavin send out, MT etc. forms, and is to simplify the problem complexity, the present embodiment is set the inner controllable electric power power stage of microgrid and is consisted of than the power of low capacity output sum a plurality of of same type,

$P_{\mathrm{gc}}\left[n\right]=\underset{j=1}{\overset{N_{\mathrm{gc}}}{\mathrm{\&Sigma;}}}{P}_{\mathrm{gc},j}\left[n\right]---\left(7\right)$

In formula, N _gcrepresent that controllable electric power is by N _gcindividual electric power generating composition of the same type.J=1 ..., N _gcrepresent of the same type in j controllable electric power.P _{gc, j}[n] represented in corresponding n the sampling period, controllable electric power j power output size.

For guaranteeing operational efficiency and extending unit durability, controllable electric power power stage P _{gc, j}[n] needs to meet following constraint:

$u_{\mathrm{gc},j}\left[n\right]P_{\mathrm{gc},j}^{\min }\&le;P_{\mathrm{gc},j}\left[n\right]\&le;u_{\mathrm{gc},j}\left[n\right]P_{\mathrm{gc},j}^{\max }---\left(8\right)$

In formula, u _{gc, j}[n], for controllable electric power operation sign, gets 0 or 1.Get 0 o'clock, representative is n sampling period, and controllable electric power j is operation not; Get the representative operation at 1 o'clock.

minimum while representing respectively controllable electric power j operation, maximum power output, cause decrease in efficiency and shortened equipment life for avoiding too low power stage,

generally get the rated power of 0.3 times;

generally get the rated power of 1 times.

From formula (7), (8), controllable electric power power output sum P in microgrid _gcneed to meet following constraint:

$\underset{j=1}{\overset{N_{\mathrm{gc}}}{\mathrm{\&Sigma;}}}{u}_{\mathrm{gc},j}{P}_{\mathrm{gc},j}^{\min }\&le;P_{\mathrm{gc}}\left[n\right]\&le;\underset{j=1}{\overset{N_{\mathrm{gc}}}{\mathrm{\&Sigma;}}}{u}_{\mathrm{gc},j}{P}_{\mathrm{gc},j}^{\max }---\left(9\right)$

$\min \left\{P_{\mathrm{gc},j}^{\min }\right\}\&le;P_{\mathrm{gc}}\left[n\right]\&le;\underset{j=1}{\overset{N_{\mathrm{gc}}}{\mathrm{\&Sigma;}}}{P}_{\mathrm{gc},j}^{\max },$ P _gc[n]＞0 (10)

The purpose of energy storage system capacity optimization is exactly to obtain to meet the minimum compensation capacity that interconnection power is controlled target call.The actual analysis result shows, the compensation capacity of energy-storage system is directly related with the compensation frequency range.Suppose f _eSthe compensation frequency range of energy-storage system is determined in representative according to result of spectrum analysis; S _eSrepresent that the required controlled power that provides of energy-storage system exports corresponding result of spectrum analysis.For avoiding energy-storage system and controllable electric power output to influence each other, make f _eSwith f _gcmutually disjoint; And f _eSuf _gc=f _ned, now interconnection power control target requirement will meet naturally.

In general, same bin width, the required energy storage system capacity of high compensation frequency range can be less than low compensation frequency range.The low frequency component that the general suitable compensation of controllable electric power starts from DC component, energy-storage system compensates all the other wave components, and hence one can see that under the prerequisite that meets constraint formula (1), f _gcscope is wider, and the frequency range of the required compensation of energy-storage system is just less, and energy storage system capacity is also just less.When definite controllable electric power compensation frequency range, can adopt try and error method, from DC component, gradually frequency range is extended to high band, utilize the controllable electric power power stage corresponding to the different compensation of analytical method check frequency range of front whether to meet constraint (10), and then determine and can meet controllable electric power power output constraint, can guarantee again the controllable electric power compensation frequency range that energy storage system capacity is as far as possible little, and then obtain the idealized power stage of controllable electric power.

3) according to the ideal value of controllable electric power power stage, under the impact of considering the factors such as energy-storage system efficiency for charge-discharge, determine the energy-storage system power stage can guarantee the energy-storage system continuous and steady operation, and then the required maximum of definite energy-storage system discharges and recharges power, that is its rated power.

At definite controllable electric power ideal power output P _gcafterwards, the output of energy-storage system power demand can be by column vector P _eS0=[P _eS0[1] ..., P _eS0[n] ..., P _eS0[N _s]] ^tmean:

P _ES0[n]＝P _ned[n]-P _gc[n] (11)

In actual energy-storage system, have certain loss in its charge and discharge process, the efficiency that energy-storage system discharges and recharges a circulation is called the energy-storage system overall efficiency, uses η _eSmean.According to the power stage value of required energy-storage system, consider the overall efficiency of energy-storage system, can determine the actual power that discharges and recharges of energy-storage system, use P _eS=[P _eS[1] ..., P _eS[n] ..., P _eS[N _s]] ^tmean:

$P_{\mathrm{ES}}\left[n\right]=\left\{\begin{array}{cc}{P}_{\mathrm{ES}0}\left[n\right]/{\mathrm{\&eta;}}_{\mathrm{ES},d}& P_{\mathrm{ES}0}\left[n\right]\&GreaterEqual;0\\ P_{\mathrm{ES}0}\left[n\right]{\mathrm{g\&eta;}}_{\mathrm{ES},c}& P_{\mathrm{ES}0}\left[n\right]<0\end{array}\right.---\left(12\right)$

In formula, η _{eS, c}and η _{eS, d}represent respectively energy-storage system charge efficiency and discharging efficiency, if supposition energy-storage system efficiency for charge-discharge is equal,

after considering and discharging and recharging power loss, when electric discharge, after the loss of energy-storage system actual discharge power deduction, need to meet required discharge power requirement, its value for required discharge power divided by discharging efficiency; When charging, the actual charge power of energy-storage system is the value after required charge power deduction charging loss, should be required charge power and is multiplied by charge efficiency.

Interconnection power after the energy-storage system compensation not only will meet the control target call, also will guarantee that energy-storage system can continuous and steady operation., require in whole sample cycle, in the energy-storage system running, satisfied (putting) power consumption that only fills is zero, that is: for this reason

$\mathrm{\&Delta;E}=\underset{n=1}{\overset{\mathrm{Ns}}{\mathrm{\&Sigma;}}}\left(P_{\mathrm{ES}}\right[n\left]\right)=0---\left(13\right).$

When the power that utilizes energy-storage system to given frequency range compensates, what compensate due to the power fluctuation to each frequency is complete cycle amount, if do not consider the loss that discharges and recharges of energy-storage system, the required charge capacity of energy-storage system should equal discharge electricity amount, that is to say that constraints (13) will meet naturally.Yet, energy-storage system actual efficiency η _eSbe less than 100%, now, the actual charge volume of energy-storage system should be less than discharge capacity, i.e. Δ E>0.For guaranteeing that the output of system power target meets constraint (13), can control target P by microgrid interconnection power _tLthe whole upwards translation of whole translation downwards or controllable electric power power stage realizes.The translational movement absolute value is designated as Δ P, can obtain by iterative computation.After translation, the energy-storage system power demand is output as:

P _ES0[n]＝P _ned[n]-ΔP-P _gc[n] (14)

Utilize formula (12) can obtain the actual performance number that discharges and recharges of energy-storage system after consideration discharges and recharges power loss.

In whole sample data in the cycle, the actual power P that discharges and recharges of the energy-storage system obtained _eSthe maximum of absolute value is the maximum that energy-storage system should possess and discharges and recharges power, that is the energy-storage system power-handling capability:

$P_{\mathrm{ES}}^n=\max \left\{\right|P_{\mathrm{ES}}\left[n\right]\left|\right\}---\left(15\right)$

Three, capacity and initial SOC determine

Control the demand of target for meeting level and smooth interconnection power, energy-storage system should possess enough large capacity.For definite energy-storage system power stage, the required heap(ed) capacity of energy-storage system can utilize simulation method to obtain equally.Its calculation procedure is as follows:

1) the energy-storage system real output data based on definite, add up the energy-storage system charge/discharge electricity amount of each sample point, can obtain the energy hunting of different sampling instant energy-storage systems with respect to initial condition, that is:

$E_{\mathrm{ES},\mathrm{ac}}\left[m\right]=\underset{0}{\overset{m}{\mathrm{\&Sigma;}}}\left(P_{\mathrm{ES}}\right[m]g{T}_s/3600),$ m＝0，...，N _s (16)

In formula, T _s/ 3600 mean chronomere's " second " convert be chronomere " hour ".E _{eS, ac}[m] represents energy-storage system energy hunting with respect to initial condition m sampling instant, that is m (from the 0th to the m) sampling period before corresponding, energy-storage system accumulative total charge-discharge energy sum [kWh].

2) for energy-storage system energy hunting in the cycle in whole sample data, calculate the poor of energy-storage system maximum, least energy, consider energy-storage system SOC restriction, obtain the capacity that energy-storage system should possess, that is energy-storage system rated capacity value:

$E_{\mathrm{ES}}^n=\frac{\max \left\{E_{\mathrm{ES},\mathrm{ac}}\right[m\left]\right\}-\min \left\{E_{\mathrm{ES},\mathrm{ac}}\right[m\left]\right\}}{{\mathrm{SOC}}_{\max }-{\mathrm{SOC}}_{\min }}---\left(17\right)$

In formula, SOC _maxand SOC _minrepresent respectively the upper and lower limit constraint of SOC in the energy-storage system actual motion.Ideally, SOC _max=1, SOC _min=0.Ring energy-storage system life-span, SOC for fear of overcharging, cross film playback while considering the energy-storage system actual motion _maxand SOC _minshould be suitably in [0,1] interior value; Max{E _{eS, ac}[m] }, min{E _{eS, ac}[m] } represent respectively in the whole sample data cycle that energy-storage system is with respect to minimum, the ceiling capacity of initial condition, max{E _{eS, ac}[m] }-min{E _{eS, ac}[m] } represented the absolute value of energy-storage system ceiling capacity fluctuation in the whole sample data cycle.

3), after determining energy storage system capacity, if in the time of will guaranteeing the energy-storage system operation, SOC is no more than restriction range, the SOC initial value need to meet certain requirement.

After obtaining energy storage system capacity by formula (17), can judge whether the gained capacity meets constraint by verification energy-storage system SOC range of operation.SOC may be defined as energy-storage system dump energy level, and Related Computational Methods is:

$\mathrm{SOC}\left[m\right]=\mathrm{SOC}\left[n\right]-\frac{E_{\mathrm{ES},\mathrm{ac}}\left[m\right]}{E_{\mathrm{ES}}^n}---\left(18\right)$

In formula, SOC[0] represent the initial SOC value of energy-storage system.

If energy storage system capacity satisfies the demands, in the time of guaranteeing the energy-storage system operation, SOC is no more than restriction range, and the SOC initial value need to meet certain requirement.Can show that according to formula (17), (18) SOC initial value computing formula is as follows:

$\mathrm{SOC}\left[0\right]={\mathrm{SOC}}_{\min }+\frac{\max \left\{E_{\mathrm{ES},\mathrm{ac}}\right[m\left]\right\}}{E_{\mathrm{ES}}^n}={\mathrm{SOC}}_{\max }+\frac{\min \left\{E_{\mathrm{ES},\mathrm{ac}}\right[m\left]\right\}}{E_{\mathrm{ES}}^n}---\left(19\right)$

From SOC initial value computing formula, after the energy-storage system minimum capacity that meets constraint is determined, the SOC initial value of corresponding unique satisfied constraint has also just been determined.Although some harshness of this condition, in real system, this initial condition can move a period of time at energy-storage system and naturally be met after reaching stable state.

Below with high regenerative resource permeability microgrid data, verify that energy storage system capacity determines method.Microgrid consists of miniature combustion engine (being abbreviated as MT), 250kW load and the energy-storage system of 120kW photovoltaic, 2*75kW, as shown in Figure 1.Wherein, photovoltaic power output data are China's certain electric power saving Testing & Research Institute photovoltaic plant pilot system whole day sampled data on August 5th, 2009, and the sampling period is 1 minute, as shown in accompanying drawing 2 solid lines.The photovoltaic Maximum Power Output is 86.4kW, and minimum power is 0, and average output power is 17.05kW.The load data peak load is 250kW, and waveform is with reference to the first distributed energy storage system of the U.S. that is positioned at Chemical Station on July 10th, the 2006 load waveform of first operation day, as shown in 2 pairs of line of accompanying drawing.The MT that in microgrid, controllable electric power is 75kW by two rated power forms, and during every MT operation, minimum operate power is 22.5kW (i.e. the rated power of 0.3 times), and maximum operate power is 75kW (i.e. the rated power of 1 times).From formula (10), during the MT operation, power stage sum minimum value is 22.5kW, and maximum power is 150kW.For without loss of generality, suppose that the MT real work determining heat pattern (otherwise can't regulate to process, following the tracks of the photovoltaic exporting change) with electricity.The comprehensive efficiency for charge-discharge η of energy-storage system _eSbe taken as 88%, and supposition charging and discharging efficiency is equal, is 93.81%; The SOC upper limit gets 1, and lower limit gets 0.3.Microgrid interconnection power is controlled target P _tLfor-100kW, guarantee that the power that electrical network injects to microgrid is 100kW.The Power Exchange amount between microgrid and electrical network of it should be noted that not necessarily only has a value in one day, can be different in the peak valley time period, i.e. and given interconnection power ratio control P in literary composition _tLcan be variate, but without loss of generality, this example be only considered fixed value.

At first, determine the required controlled power output of microgrid P _ned, and it is carried out to discrete Fourier transform.

Photovoltaic output P in known microgrid _gr, the load P _land microgrid interconnection target P _tL, by formula (2), (3), can obtain respectively microgrid net load P _lnetwith the required controlled power output of microgrid sum P _ned, respectively as shown in accompanying drawing 2 dotted lines and accompanying drawing 3.Based on discrete Fourier transform, the required controlled power of microgrid is exported to P _nedcarry out spectrum analysis, its result as shown in Figure 4.Accompanying drawing 4 has provided sample data in the Nyquist frequency f _n=8.333 * 10 ^-3amplitude-frequency characteristic before Hz.

Based on result of spectrum analysis, can determine and can meet the constraint of controllable electric power power output, can guarantee again the controllable electric power compensation frequency range that energy storage system capacity is as far as possible little, and then obtain the idealized power stage for the controllable electric power of this compensation frequency range.For explaining conveniently, band limits is described by corresponding periodic quantity.If the compensation cycle scope is [T _l, T _u), T _l, T _urepresent respectively compensation cycle lower limit and the upper limit.Because energy-storage system self can not produce power, therefore MT needs compensating direct current component (corresponding frequency is 0Hz), compensation cycle upper limit T _ube made as infinity.Generally speaking, the compensating frequency scope is larger, and the controllable electric power power fluctuation is larger, as shown in accompanying drawing 5a.Adopt try and error method to search and meet T corresponding to the maximum compensation range of MT that the MT power fluctuation retrains [22.5,150] kW _l=130 minutes, as shown in accompanying drawing 5a.The MT compensation range is larger, and the required compensation range of energy-storage system is less, and its desired volume is just less, as shown in accompanying drawing 5b.

From accompanying drawing 5a, the maximum compensation range that meets MT power stage constraint for [130 ,+∞) minute, the MT power stage P that this compensation range is corresponding _gcsee accompanying drawing 6a solid line, its power stage scope is [22.686,137.664] kW, meets the constraint of MT power output.

After guaranteeing that energy-storage system deduction discharges and recharges loss, sample data in the cycle actual charge/discharge electricity amount equate, by P _tLwhole translation Δ P=0.258kW downwards, the energy-storage system power demand that is met energy-storage system continuous and steady operation constraint (13) is exported P _eS0, the comprehensive efficiency for charge-discharge of consideration energy-storage system 88%, determine the actual power P that discharges and recharges of energy-storage system _eS, as shown in accompanying drawing 6a dotted line.Can determine energy-storage system rated power, capacity and SOC initial value according to formula (15), (17), (19), as shown in table 1.

The optimum capacity scheme of table 1

Definite energy-storage system power, capacity are carried out to verification, and in its running, the SOC size is as shown in accompanying drawing 6b dotted line, and known SOC maximum and minimum value are respectively 100%, 30%, just equals the constraint of SOC bound; During end of run, to charge and discharge electric weight be 0 to the actual accumulative total of energy-storage system, sees accompanying drawing 6b solid line, therefore definite capacity scheme can guarantee the energy-storage system continuous and steady operation.

Claims (9)

1. the energy storage system capacity optimization method of a level and smooth microgrid interconnection tie power fluctuation, is characterized in that, includes following steps:

1) determine rational regenerative resource power output and load sample data, wherein, regenerative resource power stage and load sample sampling period get and are more than or equal to 1 minute, be less than or equal to a numerical value of 1 hour, described regenerative resource power stage and load sample data comprise sampling period or sample frequency, sampling beginning and ending time, sampling length;

2) according to regenerative resource power output and load sample data, utilize simulation method to determine energy-storage system power,

The described simulation method of utilizing is determined energy-storage system power, comprises the steps:

(1) determine the required controlled power output of microgrid P _ned, and it is carried out to discrete Fourier transform;

(2) based on the required controlled power output of microgrid P _nedresult of spectrum analysis, determine that meet microgrid interconnection power controls target P _tLfrequency domain scope and the time domain power stage corresponding to the required compensation frequency domain of this controllable electric power scope of the required compensation of controllable electric power of constraint;

(3) according to the ideal value of controllable electric power power stage, under the impact of considering energy-storage system efficiency for charge-discharge factor, determine the energy-storage system power stage can guarantee the energy-storage system continuous and steady operation, and then the required maximum of definite energy-storage system discharges and recharges power, that is its rated power;

3) according to the output of energy-storage system power demand, utilize simulation method to determine capacity and initial SOC state.

2. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 1, is characterized in that, the required controlled power output of described definite microgrid P _ned, and it is carried out to discrete Fourier transform, specifically:

Set microgrid by batch (-type) regenerative resource, controllable electric power, energy-storage system and load structure, corresponding output is respectively by column vector P _gr, P _gc, P _eS0and P _lmean, for meeting microgrid interconnection power, control target P _tLdemand has following power constraint:

P _gr-P _L+P _ES0+P _gc=P _TL

P _gr[n]-P _L[n]+P _ES0[n]+P _gc[n]=P _TL[n] （1）

n∈{1,...,N _s}

In formula, P _*[n] represents column vector P _*in n element, i.e. n the power output [kW] that sampled point is corresponding, N _srepresent the sampled point number, the span of n is the same; P _*the sample frequency of the sampled data of representative, sampled point number and sampling beginning and ending time are all identical, make f _s, T _sbe respectively sample data P _*sample frequency [Hz] and sampling period [s]; P _eS0[n] can just can bear, and for just representing energy storage system discharges, is negative representative charging; P _tL[n] also can just can bear, and for just representing that microgrid is to the electrical network power output, for negative, represents that electrical network is to the microgrid injecting power;

Load is deducted to the regenerative resource power stage and be defined as net load P _lnet, that is:

P _Lnet=P _L-P _gr （2）

Control target P at known microgrid interconnection power _tLafter, can determine the required controlled power output of microgrid sum P by formula (1), (2) _ned:

P _ned=P _TL+P _Lnet=P _ES0+P _gc （3）

Formula (3) shows the required controlled power output of microgrid P _nedcontrol target and net load decision by microgrid interconnection power, provided by energy-storage system and controllable electric power;

To required controlled power output P in microgrid _nedcarry out spectrum analysis, obtain amplitude-frequency S as a result _nedand f _ned,

S _ned=DFT(P _ned)=[S _ned[1],...,S _ned[n],...,S _ned[N _s]] ^T （4）

f _ned=[f _ned[1],...,f _ned[n],...,f _ned[N _s]] ^T

DFT (P _ned) represent sample data P _nedcarry out discrete Fourier transform, S _ned[n]=R _ned[n]+I _ned[n] i represents n frequency f in the Fourier transform result _nedthe amplitude that [n] is corresponding, R _ned[n], I _ned[n] respectively for real part and the imaginary part of amplitude, f _nedfor with S _nedcorresponding column of frequencies vector.

3. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 1, is characterized in that, described based on the required controlled power output of microgrid P _nedresult of spectrum analysis, determine that meet microgrid interconnection power controls target P _tLfrequency domain scope and the time domain power stage corresponding to the required compensation frequency domain of this controllable electric power scope of the required compensation of controllable electric power of constraint, specifically:

Set f _gcthe compensation frequency range of controllable electric power is determined in representative according to result of spectrum analysis; S _gcrepresenting that controllable electric power is required provides the result of spectrum analysis that power stage is corresponding,

$S_{\mathrm{gc}}\left[n\right]=\left\{\begin{array}{cc}{S}_{\mathrm{ned}}\left[n\right]& f_{\mathrm{gc}}\&Element;f_{\mathrm{gc}}\\ 0+0i& f_{\mathrm{gc}}\&NotElement;f_{\mathrm{gc}}\end{array}\right.---\left(5\right)$

To S _gccarry out the discrete fourier inverse transformation the required controlled power Output rusults P that provides of controllable electric power is provided _gc:

P _gc=IDFT(S _gc)=[P _gc[1],...,P _gc[n],...,P _gc[N _s]] ^T （6）

In formula, IDFT (S _gc) represent S _gccarry out the discrete fourier inverse transformation;

Setting the inner controllable electric power power stage of microgrid is:

$P_{\mathrm{gc}}\left[n\right]=\underset{j=1}{\overset{N_{\mathrm{gc}}}{\mathrm{\&Sigma;}}}{P}_{\mathrm{gc},j}\left[n\right]---\left(7\right)$

In formula, N _gcrepresent that controllable electric power is by N _gcindividual electric power generating composition of the same type; J=1 ..., N _gcrepresent of the same type in j controllable electric power, P _{gc, j}[n] represented in corresponding n the sampling period, controllable electric power j power output size;

For guaranteeing operational efficiency and extending unit durability, controllable electric power power stage P _{gc, j}[n] needs to meet following constraint:

$u_{\mathrm{gc},j}\left[n\right]P_{\mathrm{gc},j}^{\min }\&le;P_{\mathrm{gc},j}\left[n\right]\&le;u_{\mathrm{gc},j}\left[n\right]P_{\mathrm{gc},j}^{\max }---\left(8\right)$

In formula, u _{gc, j}[n], for controllable electric power operation sign, gets 0 or 1; Get 0 o'clock, representative is n sampling period, and controllable electric power j is operation not; Get the representative operation at 1 o'clock;

minimum while representing respectively controllable electric power j operation, maximum power output, cause decrease in efficiency and shortened equipment life for avoiding too low power stage,

get the rated power of 0.3 times; get the rated power of 1 times;

From formula (7), (8), controllable electric power power output sum P in microgrid _gcneed to meet following constraint:

$\underset{j=1}{\overset{N_{\mathrm{gc}}}{\mathrm{\&Sigma;}}}{u}_{\mathrm{gc},j}{P}_{\mathrm{gc},j}^{\min }\&le;P_{\mathrm{gc}}\left[n\right]\&le;\underset{j=1}{\overset{N_{\mathrm{gc}}}{\mathrm{\&Sigma;}}}{u}_{\mathrm{gc},j}{P}_{\mathrm{gc},j}^{\max }---\left(9\right)$

$\min \left\{P_{\mathrm{gc},j}^{\min }\right\}\&le;P_{\mathrm{gc}}\left[n\right]\&le;\underset{j=1}{\overset{N_{\mathrm{gc}}}{\mathrm{\&Sigma;}}}{P}_{\mathrm{gc},j}^{\max },P_{\mathrm{gc}}\left[n\right]>0---\left(10\right)$

Determine the output of controllable electric power ideal power, at first will select rational controllable electric power frequency domain compensation scope f _gcadopt try and error method, from DC component, gradually frequency range is extended to high band, utilize the controllable electric power power stage corresponding to analytical method check different compensation frequency range of front whether to meet formula (10), and then determine and can meet controllable electric power power output constraint, can guarantee again the controllable electric power compensation frequency range that energy storage system capacity is as far as possible little, and then obtain the idealized power stage of controllable electric power.

4. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 1, is characterized in that, described energy-storage system power stage, and energy-storage system rated power definite:

According to controllable electric power ideal power output P _gc, the energy-storage system power demand is exported by column vector P _eS0=[P _eS0[1] ..., P _eS0[n] ..., P _eS0[N _s]] ^tmean:

P _ES0[n]=P _ned[n]-P _gc[n] （11）

Energy-storage system overall efficiency η _eSmean, the actual power that discharges and recharges of energy-storage system, use P _eS=[P _eS[1] ..., P _eS[n] ..., P _eS[N _s]] ^tmean:

$P_{\mathrm{ES}}\left[n\right]=\left\{\begin{array}{cc}{P}_{\mathrm{ES}0}\left[n\right]/{\mathrm{\&eta;}}_{\mathrm{ES},d}& P_{\mathrm{ES}0}\left[n\right]\&GreaterEqual;0\\ P_{\mathrm{ES}0}\left[n\right]\&CenterDot;{\mathrm{\&eta;}}_{\mathrm{ES},c}& P_{\mathrm{ES}0}\left[n\right]<0\end{array}\right.---\left(12\right)$

In formula, η _{eS, c}and η _{eS, d}represent respectively energy-storage system charge efficiency and discharging efficiency;

In whole sample cycle, for guaranteeing the energy-storage system continuous and steady operation, needing to meet clean charge/discharge electric weight in the energy-storage system running, be zero, that is:

$\mathrm{\&Delta;E}=\underset{n=1}{\overset{\mathrm{Ns}}{\mathrm{\&Sigma;}}}\left(P_{\mathrm{ES}}\right[n\left]\right)=0---\left(13\right).$

5. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 4, is characterized in that, for guaranteeing the output of system power target, meets:

$\mathrm{\&Delta;E}=\underset{n=1}{\overset{\mathrm{Ns}}{\mathrm{\&Sigma;}}}\left(P_{\mathrm{ES}}\right[n\left]\right)=0$

Microgrid interconnection power is controlled to target P _tLthe whole upwards translation of whole translation downwards or controllable electric power power stage realizes; The translational movement absolute value is designated as Δ P, by iterative computation, obtains; After translation, the energy-storage system power demand is output as:

P _ES0[n]=P _ned[n]-ΔP-P _gc[n] （14）

Utilize formula $P_{\mathrm{ES}}\left[n\right]=\left\{\begin{array}{cc}{P}_{\mathrm{ES}0}\left[n\right]/{\mathrm{\&eta;}}_{\mathrm{ES},d}& P_{\mathrm{ES}0}\left[n\right]\&GreaterEqual;0\\ P_{\mathrm{ES}0}\left[n\right]\&CenterDot;{\mathrm{\&eta;}}_{\mathrm{ES},c}& P_{\mathrm{ES}0}\left[n\right]<0\end{array}\right.$ Obtain the actual performance number that discharges and recharges of energy-storage system after consideration discharges and recharges power loss; In whole sample data in the cycle, the actual power P that discharges and recharges of the energy-storage system obtained _eSthe maximum of absolute value is the energy-storage system power-handling capability:

$P_{\mathrm{ES}}^n=\max \left\{\right|P_{\mathrm{ES}}\left[n\right]\left|\right\}---\left(15\right).$

6. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 1, is characterized in that, the described simulation method of utilizing is determined capacity and initial SOC state, comprises the steps:

(1) the energy-storage system real output data based on definite, add up the energy-storage system charge/discharge electricity amount of each sample point, obtains the energy hunting of different sampling instant energy-storage systems with respect to initial condition;

(2) for energy-storage system energy hunting in the cycle in whole sample data, calculate the poor of energy-storage system maximum, least energy, consider energy-storage system SOC restriction, obtain the capacity that energy-storage system should possess, that is energy-storage system rated capacity value;

(3), after determining energy storage system capacity, SOC is no more than restriction range when guaranteeing the energy-storage system operation, set the SOC initial value will be satisfied condition.

7. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 6, is characterized in that, the different sampling instant energy-storage systems of described acquisition, with respect to the energy hunting of initial condition, specifically adopt following formula:

$E_{\mathrm{ES},\mathrm{ac}}\left[m\right]=\underset{0}{\overset{m}{\mathrm{\&Sigma;}}}\left(P_{\mathrm{ES}}\right[m]\&CenterDot;T_s/3600),m=0,...,N_s---\left(16\right)$

In formula, T _s/ 3600 mean chronomere's " second " convert be chronomere " hour "; E _{eS, ac}[m] represents energy-storage system energy hunting with respect to initial condition m sampling instant, that is m the sampling period before corresponding, that is, from the 0th to m sampling period, energy-storage system accumulative total charge-discharge energy sum [kWh].

8. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 6, is characterized in that, describedly obtains the capacity that energy-storage system should possess, that is energy-storage system rated capacity value, specifically adopts following formula:

$E_{\mathrm{ES}}^n=\frac{\max \left\{E_{\mathrm{ES},\mathrm{ac}}\right[m\left]\right\}-\min \left\{E_{\mathrm{ES},\mathrm{ac}}\right[m\left]\right\}}{{\mathrm{SOC}}_{\max }-{\mathrm{SOC}}_{\min }}---\left(17\right)$

In formula, SOC _maxand SOC _minrepresent respectively the upper and lower limit constraint of SOC in the energy-storage system actual motion, max{E _{eS, ac}[m] }-min{E _{eS, ac}[m] } represented the absolute value of energy-storage system ceiling capacity fluctuation in the whole sample data cycle.

9. the energy storage system capacity optimization method of level and smooth microgrid interconnection tie power fluctuation according to claim 8, is characterized in that, described SOC initial value will satisfied condition be to adopt following formula to obtain:

$\mathrm{SOC}\left[m\right]=\mathrm{SOC}\left[0\right]-\frac{E_{\mathrm{ES},\mathrm{ac}}\left[m\right]}{E_{\mathrm{ES}}^n}---\left(18\right)$

In formula, SOC[0] represent the initial SOC value of energy-storage system;

If energy storage system capacity satisfies the demands, in the time of guaranteeing the energy-storage system operation, SOC is no more than restriction range, and the SOC initial value need to meet following initial value computing formula:

$\mathrm{SOC}\left[0\right]{=\mathrm{SOC}}_{\min }+\frac{\max \left\{E_{\mathrm{ES},\mathrm{ac}}\right[m\left]\right\}}{E_{\mathrm{ES}}^n}={\mathrm{SOC}}_{\max }+\frac{\min \left\{E_{\mathrm{ES},\mathrm{ac}}\right[m\left]\right\}}{E_{\mathrm{ES}}^n}---\left(19\right).$

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