CN104701865A - Voltage flicker detecting and control method based on battery energy storage system - Google Patents

Abstract

The invention provides a voltage flicker detecting and control method based on battery energy storage system; the method comprises the steps: step (1) acquiring a single-phase voltage signal at a PCC (Program-controlled Computer) and changing the phase to obtain three-phase voltage and current signals; step (2), transforming the three-phase voltage and current signals obtained in the step (1) and obtaining instant active power and reactive power; step (3), filtering the obtained instant active power and extracting a DC component to calculate a voltage flicker enveloping signal; step (4) calculating voltage flicker parameters, including an amplitude value and a frequency; and step (5) solving a compensation command of the battery energy storage system and compensating active and reactive power to public nodes. The provided voltage flicker detecting and control method is capable of accurately detecting the corresponding parameters of the voltage flicker; the calculation method is simple and the engineering is easy in realization. The battery energy storage system is applied to a power distribution network to compensate the voltage flicker; in combination of the provided control method, the active and reactive power can be compensated at the same time and the voltage flicker in the power distribution network is restrained effectively.

Description

A kind of voltage flicker detection control method based on battery energy storage system

Technical field

The present invention relates to a kind of compensating control method, specifically relate to a kind of voltage flicker detection control method based on battery energy storage system.

Background technology

The irregular fluctuation causing public access point voltage in power distribution network of load, the voltage fluctuation of frequency between 1-10Hz becomes voltage flicker.Voltage flicker can cause the decrease in efficiency of electric equipment, causes the vibration of torque and power, even also can affect protection system, comparatively large to the hazard ratio of electrical network, therefore needs detect it and compensate.

Voltage flicker detection conventional at present has half-wave virtual value method, square demod-ulation method, full-wave rectification method etc., but the effect of these methods is unsatisfactory.Adopt and can improve Detection results based on the synchronization signal detection method of Wavelet Multi-resolution Transform, but this method needs that frequency division is strict, the wavelet basis of concentration of energy and synchronizing signal accurately, in actual applications and be not easy to realize.Therefore, design be convenient to realize and the obvious Voltage flicker detection of Detection results is very meaningful.

And in the compensation method of voltage flicker, traditional reactive power compensator SVC response speed is slow, effect is undesirable.Adopt STATCOM to suppress voltage flicker can obtain good inhibition, but in the power distribution network that impedance comparison is large, only compensating power effectively can not suppress voltage flicker, still needs to compensate certain active power.

Summary of the invention

For the deficiencies in the prior art, the present invention proposes a kind of voltage flicker detection control method based on battery energy storage system, battery energy storage system is linked into the common node place of power distribution network, for guarantee power factor is constant, only need know the active power needed for network load, then can utilize battery energy storage system compensating power and meritorious and idle fluctuating power, and then make the amplitude of the voltage at common node place and phase angle keep constant, suppress voltage flicker.

The object of the invention is to adopt following technical proposals to realize:

Based on a voltage flicker detection control method for battery energy storage system, its improvements are, described method comprises

(1) gather the single-phase voltage signal at PCC place, change phase place and obtain three-phase voltage and current signal;

(2) three-phase voltage that obtains of shift step (1) and three-phase current signal, obtains instantaneous active power and reactive power;

(3) filtering is carried out to the instantaneous active power that step (2) obtains, extract DC component and carry out calculating voltage flicker envelope signal;

(4) ask voltage flicker parameter, comprise amplitude and frequency;

(5) ask the compensation order of battery energy storage system and compensate meritorious and reactive power to common node.

Preferably, described step (1) comprises the single-phase voltage signal gathering PCC, changes phase place and obtains three-phase voltage and current signal, if u _a(t)=E _ksin (k ω t+ φ _k) (k>=1), in three-phase symmetrical system, respectively there is identical voltage waveform mutually and phase 120 °, replace current signal with voltage signal, can obtain thus:

$\left\{\begin{array}{cc}{u}_a\left(t\right)=u_a\left(t\right)& i_a\left(t\right)=u_a\left(t\right)\\ u_b\left(t\right)=-u_a\left(t\right)-u_c\left(t\right)& i_b\left(t\right)=u_b\left(t\right)\\ u_c\left(t\right)=-u_a(t-\frac{T}{6})& i_c\left(t\right)=u_c\left(t\right)\end{array}\right.,$ Wherein, u _afor A phase voltage amplitude; T is the time; E _kfundamental voltage amplitude; φ _kinitial phase angle; K is t phase adjust coefficient; ω is power frequency angular frequency; U is line voltage rated value; T is power frequency period.

Preferably, described step (2) utilizes instantaneous reactive power theory to convert three-phase voltage and three-phase current signal, obtains instantaneous active power and reactive power.

Preferably, described step (3) comprises DC component calculating voltage flicker envelope signal instantaneous active power being carried out to filtering extraction.

Further, describedly carry out filtering to instantaneous active power and extract DC component calculating voltage flicker envelope signal, filtering is calculated as: $p^{\′}\left(t\right)=\frac{1}{32}\underset{k=1}{\overset{32}{\mathrm{\Σ}}}p(t+\frac{\mathrm{kT}}{32})$

Then voltage signal is: $E\left(t\right)=\sqrt{\frac{2}{3}{p}^{\′}\left(t\right)}$

Wherein, p ' is active power superposition apparent value; P is active power value; E is voltage signal effective value.

Preferably, described step (4) comprises the amplitude and the frequency that utilize Fourier transform to calculate voltage flicker.

Further, utilize the envelope signal of fast Fourier transform FFT process voltage flicker, the amplitude of calculating voltage flickering and frequency, for the interference of harmonic inhabitation and noise, thus accurately obtain amplitude and the frequency parameter of voltage flicker.

Preferably, described step (5) comprises the compensation order being obtained battery energy storage system by voltage flicker calculation of parameter, controls battery energy storage system and compensates meritorious and reactive power to common node.

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

Battery energy storage system is linked into the common node place of power distribution network by the present invention, utilizes battery energy storage system to suppress voltage flicker.When detecting voltage flicker signal, only gather single-phase voltage signal, three-phase voltage and current signal is obtained by changing phase place, recycling instantaneous reactive power theory calculates instantaneous active power, calculate the envelope of voltage signal after filtering afterwards, recycling high accuracy Fourier calculates frequency and the amplitude of flickering, and then calculate the compensation order of battery energy storage system, battery energy storage system can system according to current feed-forward decoupling control policy, quick response, sends certain reactive power and active power with bucking voltage flickering.The Voltage flicker detection that application the present invention proposes can detect the relevant parameter of voltage flicker exactly, and algorithm is simple, is easy to Project Realization.Application battery energy storage system carries out voltage flicker compensation in power distribution network, in conjunction with the control method that the present invention proposes, can compensate meritorious and reactive power simultaneously, effectively suppresses the voltage flicker in power distribution network.

Accompanying drawing explanation

Fig. 1 is a kind of voltage flicker detection control Method And Principle figure based on battery energy storage system provided by the invention.

Fig. 2 is that voltage flicker provided by the invention detects the schematic diagram with compensation method.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in further detail.

The invention provides a kind of voltage flicker detection control method based on battery energy storage system, battery energy storage system is linked into the common node place of power distribution network, for guarantee power factor is constant, only need know the active power needed for network load, then can utilize battery energy storage system compensating power and meritorious and idle fluctuating power, and then make the amplitude of the voltage at common node place and phase angle keep constant, suppress voltage flicker.

Concrete steps of the present invention are as follows:

Step one, gathers the single-phase voltage signal at common node place, obtains three-phase voltage and current signal by changing phase place;

Step 2, utilizes instantaneous reactive power theory to convert three-phase voltage and three-phase current signal, obtains instantaneous active power and reactive power;

Step 3, carries out filtering to instantaneous active power, extracts DC component and carrys out calculating voltage signal;

Step 4, utilizes fast Fourier transform FFT (Fast Fourier Transformation) to calculate amplitude and the frequency of voltage flicker;

Step 5, is obtained the compensation order of battery energy storage system by voltage flicker calculation of parameter, control battery energy storage system and compensate corresponding meritorious and reactive power to common node.

Embodiment

As shown in Figure 1, the schematic diagram for utilizing battery energy storage system to carry out voltage flicker compensation.From the angle of power flow, the power that arc furnace even load absorbs can be decomposed into two components: constant (P ₀, Q ₀) and fluctuating power (Δ P, Δ Q).In order to solve the voltage flicker problem caused by this kind of load in power distribution network, optimal way is by compensating Q at PCC place access BESS ₀, Δ P and Δ Q, such electrical network only need provide P ₀and its power factor is 1, thus make the amplitude of PCC place voltage and phase angle keep constant, play the object suppressing voltage flicker.Although because the impact of loss and other factor, Q ₀, Δ P and Δ Q can not realize full remuneration, but the effect of suppression voltage flicker also can be made more desirable like this.

As shown in Figure 2, for voltage flicker detects the schematic diagram with compensation method.Voltage flicker, due to reason difference, is divided into periodically and aperiodicity flickering.The present invention mainly considers periodically flickering, flickering is regarded as the low frequency modulations of offset of sinusoidal voltage, can be expressed as:

$u\left(t\right)=A\left(t\right)\cos \mathrm{\ωt}=\sqrt{2}U(1+\mathrm{Ma}\left(t\right))\cos \mathrm{\ωt}$

In formula: ω is power frequency angular frequency; U is line voltage rated value; M is the amplitude of frequency modulation, is generally taken as 1%, reaches as high as 10%; A (t) is envelope signal; A (t) is modulation signal, is taken as the modulation signal of simulation arc furnace

$a\left(t\right)=\underset{m}{\mathrm{\Σ}}\frac{1}{m}\cos \mathrm{m\Ωt}$

In formula: Ω is the first-harmonic angular frequency of modulation signal; M is harmonic number.

Like this, flickering just can regard the narrow band signal of amplitude low frequency modulations as, utilizes instantaneous reactive power theory can ask for the envelope signal of voltage flicker.Concrete step comprises:

Step one, gathers the single-phase voltage signal at PCC place, obtains three-phase voltage and current signal by changing phase place.If u _a(t)=E _ksin (k ω t+ φ _k) (k>=1), consider in three-phase symmetrical system, respectively there is identical voltage waveform mutually and phase 120 °, replace current signal with voltage signal, can obtain thus:

$\left\{\begin{array}{cc}{u}_a\left(t\right)=u_a\left(t\right)& i_a\left(t\right)=u_a\left(t\right)\\ u_b\left(t\right)=-u_a\left(t\right)-u_c\left(t\right)& i_b\left(t\right)=u_b\left(t\right)\\ u_c\left(t\right)=-u_a(t-\frac{T}{6})& i_c\left(t\right)=u_c\left(t\right)\end{array}\right.$ T is power frequency period;

Step 2, utilizes instantaneous reactive power theory to convert three-phase voltage and three-phase current signal, obtains instantaneous active power and reactive power.Processing method in step one decreases the adverse effect that three-phase imbalance brings, and owing to not having phase difference between voltage and current signal, then instantaneous reactive power is zero, only need analyze instantaneous active power;

Step 3, carries out filtering to instantaneous active power, extracts DC component and carrys out calculating voltage flicker envelope signal.Filtering is calculated as:

$p^{\′}\left(t\right)=\frac{1}{32}\underset{k=1}{\overset{32}{\mathrm{\Σ}}}p(t+\frac{\mathrm{kT}}{32})$

Then voltage signal is:

$E\left(t\right)=\sqrt{\frac{2}{3}{p}^{\′}\left(t\right)}$

Step 4, utilizes the envelope signal of high-precision FFT Fourier transform to voltage flicker to process, calculates amplitude and the frequency of voltage flicker.The windowed interpolation method of high accuracy fourier algorithm can the interference of harmonic inhabitation and noise effectively, thus accurately can obtain the parameter such as amplitude, frequency of voltage flicker;

Step 5, is obtained the compensation order of battery energy storage system by voltage flicker calculation of parameter, control battery energy storage system and compensate corresponding meritorious and reactive power to common node.

Finally should be noted that: above embodiment is only in order to illustrate that technical scheme of the present invention is not intended to limit; those of ordinary skill in the field still can modify to the specific embodiment of the present invention with reference to above-described embodiment or equivalent replacement; these do not depart from any amendment of spirit and scope of the invention or equivalent replacement, are all applying within the claims of the present invention awaited the reply.

Claims (8)

1., based on a voltage flicker detection control method for battery energy storage system, it is characterized in that, described method comprises

(1) gather the single-phase voltage signal at PCC place, change phase place and obtain three-phase voltage and current signal;

(2) three-phase voltage that obtains of shift step (1) and three-phase current signal, obtains instantaneous active power and reactive power;

(3) filtering is carried out to the instantaneous active power that step (2) obtains, extract DC component and carry out calculating voltage flicker envelope signal;

(4) ask voltage flicker parameter, comprise amplitude and frequency;

(5) ask the compensation order of battery energy storage system and compensate meritorious and reactive power to common node.

2. a kind of voltage flicker detection control method based on battery energy storage system as claimed in claim 1, is characterized in that, described step (1) comprises the single-phase voltage signal gathering PCC, changes phase place and obtains three-phase voltage and current signal, if u _a(t)=E _ksin (k ω t+ φ _k) (k>=1), in three-phase symmetrical system, respectively there is identical voltage waveform mutually and phase 120 °, replace current signal with voltage signal, can obtain thus:

$\left\{\begin{array}{cc}{u}_a\left(t\right)=u_a\left(t\right)& i_a\left(t\right)=u_a\left(t\right)\\ u_b\left(t\right)={-u}_a\left(t\right)-u_c\left(t\right)& i_b\left(t\right)=u_b\left(t\right)\\ u_c\left(t\right)={-u}_a(t-\frac{T}{6})& i_c\left(t\right)=u_c\left(t\right)\end{array}\right.,$ Wherein, u _afor A phase voltage amplitude; T is the time; E _kfundamental voltage amplitude; φ _kinitial phase angle; K is t phase adjust coefficient; ω is power frequency angular frequency; U is line voltage rated value; T is power frequency period.

3. a kind of voltage flicker detection control method based on battery energy storage system as claimed in claim 1, it is characterized in that, described step (2) utilizes instantaneous reactive power theory to convert three-phase voltage and three-phase current signal, obtains instantaneous active power and reactive power.

4. a kind of voltage flicker detection control method based on battery energy storage system as claimed in claim 1, it is characterized in that, described step (3) comprises DC component calculating voltage flicker envelope signal instantaneous active power being carried out to filtering extraction.

5. a kind of voltage flicker detection control method based on battery energy storage system as claimed in claim 4, is characterized in that, describedly carries out filtering to instantaneous active power and extracts DC component calculating voltage flicker envelope signal, and filtering is calculated as: $p^{\′}\left(t\right)=\frac{1}{32}\underset{k=1}{\overset{32}{\mathrm{\Σ}}}p(t+\frac{\mathrm{kT}}{32})$

Then voltage signal is: $E\left(t\right)=\sqrt{\frac{2}{3}{p}^{\′}\left(t\right)}$

Wherein, p ' is active power superposition apparent value; P is active power value; E is voltage signal effective value.

6. a kind of voltage flicker detection control method based on battery energy storage system as claimed in claim 1, it is characterized in that, described step (4) comprises the amplitude and the frequency that utilize Fourier transform to calculate voltage flicker.

7. a kind of voltage flicker detection control method based on battery energy storage system as claimed in claim 6, it is characterized in that, utilize the envelope signal of fast Fourier transform FFT process voltage flicker, the amplitude of calculating voltage flickering and frequency, for the interference of harmonic inhabitation and noise, thus accurately obtain amplitude and the frequency parameter of voltage flicker.

8. a kind of voltage flicker detection control method based on battery energy storage system as claimed in claim 1, it is characterized in that, described step (5) comprises the compensation order being obtained battery energy storage system by voltage flicker calculation of parameter, controls battery energy storage system and compensates meritorious and reactive power to common node.