CN103560591A - Optimizing method for output smoothness of mobile energy storage power station - Google Patents

Abstract

The invention discloses an optimizing method for output smoothness of a mobile energy storage power station. The optimizing method is characterized in that the battery storage capacity of the mobile energy storage power station is determined to be 15-25% of a new energy installed power-generating capacity. By the adoption of the method, the battery capacity of the mobile energy storage power station can be rapidly determined, the output smoothness of the mobile energy storage power station is guaranteed, optimal economy is achieved, and investment cost is saved.

Description

A kind of optimization method of mobile energy-accumulating power station output smoothing

Technical field

The present invention relates to design and the manufacture of mobile energy-accumulating power station, particularly a kind of optimization method of mobile energy-accumulating power station output smoothing.

Background technology

Battery capacity and the charge-discharge magnification of different application scenarios and the different desired mobile energy-accumulating power station of control target are not identical.Generally speaking, solving power quality problem does not need too large stored energy capacitance, and peak load shifting and tracking electrical network power curve need larger stored energy capacitance.For the higher electrical network of intelligent degree, as wind, light, storing cogeneration system, if capacity ratio is suitable, can save a large amount of costs of investment.

Energy storage power determines by the actual output of renewable energy power generation and desired value difference, and battery energy storage capacity is generally definite by the level and smooth strategy of renewable energy source power and energy scheduling strategy.But prior art does not provide concrete grammar, to determine that battery capacity moves energy-accumulating power station output effect when what numerical value best.

For above-mentioned problem, provide rational optimization method, in the output smoothing that guarantees mobile energy-accumulating power station, having best economy is the problem that prior art need to solve.

Summary of the invention

Technical problem to be solved by this invention is, a kind of optimization method of mobile energy-accumulating power station output smoothing is provided, and determines that the concrete numerical value of battery capacity has best economy in the output smoothing that guarantees mobile energy-accumulating power station.

For achieving the above object, technical scheme of the present invention is that a kind of optimization method of mobile energy-accumulating power station output smoothing, is characterized in that: described optimization method determines that the battery storage capacity of mobile energy-accumulating power station is 15%～25% of generation of electricity by new energy installed capacity.

The battery storage capacity E of mobile energy-accumulating power station in described optimization method _eSSfor storage power P _eSSintegration in time, its expression formula in S territory is:

$E_{\mathrm{ESS}}=\frac{1}{s}{P}_{\mathrm{ESS}}=\frac{1}{s}\frac{\mathrm{\τs}}{1+\mathrm{\τs}}{P}_{\mathrm{win}}=\frac{\mathrm{\τ}}{1+\mathrm{\τs}}{P}_{\mathrm{win}}$

After being scaled time-domain, expression formula is:

$E_{\mathrm{ESS}}\left(s\right)=e^{-t/z}{P}_{\mathrm{win}}\left(t\right)={\∫}_0^t{e}^{-t/z}{P}_{\mathrm{win}}(t-u)\mathrm{du};$

P wherein _eSSthe power that mobile energy-accumulating power station absorbs or emits; P _winit is the power output of generating set; τ is time constant; f _cfor cut-off frequency, power fluctuation intermediate frequency zone and low frequency range by frequency, be 0.01H _z; According to

$\mathrm{\τ}=\frac{1}{2\mathrm{\π}{f}_c}$

Determine τ=15.9s

Wherein τ is time constant; Power fluctuation intermediate frequency zone and low frequency range by frequency, be 0.01H _z.

The target of stabilizing of described optimization method fluctuates for stabilizing hour level.

An optimization method for mobile energy-accumulating power station output smoothing, owing to adopting above-mentioned method, determines the battery capacity of mobile energy-accumulating power station fast, guarantees the output smoothing of mobile energy-accumulating power station and has best economy, saves input cost.

Embodiment

Due to intermittence and the randomness of generation of electricity by new energy, there is fluctuation in its power output, utilizes energy-storage system can absorb fast or discharge active power, reactive power, and the level and smooth regenerative resource climbing rate of generating electricity by way of merging two or more grid systems, suppresses grid-connected voltage fluctuation, enhancing stability.

The mobile energy-accumulating power station of access wind energy turbine set of take is example, battery capacity optimization while consider suppressing the short time (second level) interior wind power fluctuation.Because wind power fluctuation is widely distributed in each frequency range of frequency domain, grid-connected rear also different on the impact of electric power system, therefore the definite wind-powered electricity generation fluctuation band limits that will stabilize is determined most important to energy storage system capacity.

From wind power angle analysis, existence due to the rotor inertia of wind-driven generator itself, therefore the high-frequency of wind speed fluctuation part is absorbed by rotor inertia, can not be reflected on wind power, general band limits is that fluctuations in wind speed more than 1Hz is very little to wind power influence of fluctuations, and when fluctuations in wind speed frequency is during lower than 0.1Hz, the velocity of wave motion of this part power is slower, the response speed of the automatic generation control in electrical network (AGC) can be caught up with completely, for reliable compensation is reduced to 0.01Hz by frequency range boundary, this part power fluctuation major part is compensated by AGC.Therefore, really need wind power frequency fluctuation scope that energy-storage system stabilizes at 0.01Hz between 1Hz.

Ignoring under the condition of loss, blower fan output wind power equals energy-storage system absorbed power and blower fan to electrical network injecting power sum:

P _win=P _ESS+P _g

P in above formula _eSSthe power (order is just absorbed as) that energy-storage system absorbs or emits; P _gthe power that is input to electrical network after energy-storage system is stabilized, due to P _eSScorresponding to the power fluctuating in wind power, so this part can obtain with high pass filter:

$P_{\mathrm{ESS}}=\frac{\mathrm{\τs}}{1+\mathrm{\τs}}{P}_{\mathrm{win}}$

Same P _winpower output for wind turbine generator; And

for high pass filter, τ is time constant,

f _cfor cut-off frequency, corresponding edge frequency 0.01Hz; Through energy-storage system, stabilizing the power that rear fan is input to electrical network can be expressed as:

$P_g=\frac{1}{1+\mathrm{\τs}}{P}_{\mathrm{win}}$

In above formula

for low pass filter, τ is time constant.

f _cfor cut-off frequency, corresponding edge frequency 0.01Hz.

Therefore,, in wind energy turbine set energy-storage system control strategy, active power of output reference value is P _eSS, the reference value of output reactive power is made as 0, also can arrange according to actual needs.It is pointed out that the parameter selection of low pass filter does not affect the stability of battery energy storage control system.

The size of mobile energy-accumulating power station battery capacity, had both affected the economy of energy-storage system, and the wind power that affects again energy-storage system is stabilized effect.

The design of timeconstantτ must be able to make energy-storage units effectively stabilize wind power fluctuation, therefore, it is more remarkable that the value of τ is stabilized more greatly effect, yet also will significantly improve the cost of investment of energy storage device, and it is the key of τ value design that balance is stabilized relation between effect and cost of investment.

Wave component in wind field wind power output power is absorbed by energy storage device, and the memory capacity of battery energy storage system is storage power P _eSSintegration in time, its expression formula in S territory is shown below:

$E_{\mathrm{ESS}}=\frac{1}{s}{P}_{\mathrm{ESS}}=\frac{1}{s}\frac{\mathrm{\τs}}{1+\mathrm{\τs}}{P}_{\mathrm{win}}=\frac{\mathrm{\τ}}{1+\mathrm{\τs}}{P}_{\mathrm{win}}$

After being transformed to time-domain, above formula is expressed as:

$E_{\mathrm{ESS}}\left(s\right)=e^{-t/z}{P}_{\mathrm{win}}\left(t\right)={\∫}_0^t{e}^{-t/z}{P}_{\mathrm{win}}(t-u)\mathrm{du}$

Due to the meritorious output of wind field at any time always between 0 to P _windmaxbetween, thus the stored energy of battery energy storage system be limited to up and down 0 to τ P _windmaxbetween, consider limiting case, during stored energy capacitance design, its P _windmaxfor take the power peak-peak that low pass filter export target is equilbrium position, can predict and determine by wind power; Therefore the selection of τ just will determine stored energy capacitance, because power fluctuation intermediate frequency zone and low frequency range is 0.01Hz by frequency, by

can obtain, τ=15.9s, so time constant minimum value 15.9s, this numerical value is according to stored energy capacitance minimal design.Present stage, the power fluctuation of stabilizing in the short time is the major control target of new forms of energy energy-storage system.The fluctuation of stabilizing hour level if take is target, and the battery capacity of mobile energy-accumulating power station is 15%～25% of new forms of energy installed capacity.

The present invention is above exemplarily described; obviously specific implementation of the present invention is not subject to the restrictions described above; as long as the various improvement that adopted technical solution of the present invention to carry out, or directly apply to other occasion without improvement, all within protection scope of the present invention.

Claims (3)

1. an optimization method for mobile energy-accumulating power station output smoothing, is characterized in that: described optimization method determines that the battery storage capacity of mobile energy-accumulating power station is 15%～25% of generation of electricity by new energy installed capacity.

2. the optimization method of a kind of mobile energy-accumulating power station output smoothing according to claim 1, is characterized in that: the battery storage capacity E of mobile energy-accumulating power station in described optimization method _eSSfor storage power P _eSSintegration in time, its expression formula in S territory is:

$E_{\mathrm{ESS}}=\frac{1}{s}{P}_{\mathrm{ESS}}=\frac{1}{s}\frac{\mathrm{\τs}}{1+\mathrm{\τs}}{P}_{\mathrm{win}}=\frac{\mathrm{\τ}}{1+\mathrm{\τs}}{P}_{\mathrm{win}}$

After being scaled time-domain, expression formula is:

$E_{\mathrm{ESS}}\left(s\right)=e^{-t/z}{P}_{\mathrm{win}}\left(t\right)={\∫}_0^t{e}^{-t/z}{P}_{\mathrm{win}}(t-u)\mathrm{du};$

P wherein _eSSthe power that mobile energy-accumulating power station absorbs or emits; P _winit is the power output of generating set; τ is time constant; f _cfor cut-off frequency, power fluctuation intermediate frequency zone and low frequency range by frequency, be 0.01H _z; According to

$\mathrm{\τ}=\frac{1}{2\mathrm{\π}{f}_c}$

Determine τ=15.9s

Wherein τ is time constant; Power fluctuation intermediate frequency zone and low frequency range by frequency, be 0.01H _z.

3. the optimization method of a kind of mobile energy-accumulating power station output smoothing according to claim 1, is characterized in that: the target of stabilizing of described optimization method fluctuates for stabilizing hour level.