CN101826730B - Rotating coordinate system-based high-efficiency BANG-BANG software phase locked loop - Google Patents

Abstract

The invention discloses a Bang-Bang phase locked control algorithm used for grid connection of solar energy, wind energy and other renewable energy sources. The phase lock can be efficiently realized at a high speed by the following steps: constructing a rotating coordinate system and implementing a cross product; converting the complicated algorithm of the conventional digital phase discriminators and digital filters into low-frequency pulse direct current under the rotating coordinate system; and realizing low-pass filtering by implementing Bang_Bang regulation.

Description

A kind of efficient BANG-BANG software phase-lock loop based on rotating coordinate system

Technical field

The present invention relates to electrotechnics and nonlinear Control technology.The present invention is suitable for new energy grid-connected power, particularly solar energy, wind power grid generating.

Background technology

Existing electrical network Phase Lock Technique, has the phase-locked chip of zero passage detection and dedicated hardware.Software phlase locking is taking fast fourier transform (FFT) as representative.Hardware circuit, except increase circuit complexity, designs and applies also underaction.Fft algorithm complexity and dynamic response are poor, are suitable for the application such as view data processing, grid-connected phase-locked on except taking a large amount of DSP resources, be also difficult to meet system dynamic requirements.Consider grid-connected synchronous particularity, be that mains frequency excursion is generally 50Hz ± 1%, and require the phase-locked higher real-time that has, the present invention proposes a kind of efficient, software phlase locking algorithm at a high speed, only needs four multiplication and is judged and carried out four-quadrant location by logic, just can follow the tracks of fast line voltage and realize frequency and phase place locking, and because algorithm is equivalent to direct current low-pass filtering under rotational coordinates, therefore there is good interference free performance.

Summary of the invention

The present invention is the software phlase locking algorithm that a kind of Bang_Bang regulates.Construct a space vector according to line voltage

and to make its angular frequency be ω ₀, starting phase angle is θ ₀, then construct a rotating coordinate system being formed by (ω, θ), and select pair of orthogonal base

${\stackrel{\→}{U}}_q=[\cos (\mathrm{\ωt}+\mathrm{\θ}),\sin (\mathrm{\ωt}+\mathrm{\θ}){\stackrel{\→}{U}}_d=[-\sin (\mathrm{\ωt}+\mathrm{\θ}),\cos (\mathrm{\ωt}+\mathrm{\θ})]$

Do cross product

${\stackrel{\→}{V}}_0\×{\stackrel{\→}{U}}_q=a\stackrel{\→}{K},{\stackrel{\→}{V}}_0\×{\stackrel{\→}{U}}_d=b\stackrel{\→}{K}$

direction determined by right-hand rule, and a, the symbol combination of b has determined

with position relationship, for

for the quadrant position under the coordinate system of transverse axis.If

fall within II, III quadrant, will

rotate 180 °; If

fall within I quadrant and implement the angle increment of one-δ, if

fall within IV quadrant, implement the angle increment of one+δ.Thereby can make

stably follow the tracks of fast,

be that ω follows the tracks of ω ₀, θ follows the tracks of θ ₀thereby, realize phase-locked.

Core content of the present invention is, by structure rotating coordinate system and enforcement cross product, by the complicated algorithm of conventional digital phase discriminator and digital filter, be converted into the DC quantity of low frequency pulsating under rotating coordinate system, realize low-pass filtering by implementing Bang_Bang adjusting, can realize phase-locked efficient high-speed.

Specific implementation method

If closed loop frequency is f _s, line voltage frequency is f _g, rotating coordinate system angle increment

make it and synchronized, by

obtain

Due to, f _gtherefore=50 ± 5 can establish

Structure vector

If

and

If line voltage is u ₁=V _msin (ω ₀t+ θ ₀), can obtain u by differential circuit ₂=V _mcos (ω ₀t+ θ ₀), or cosine component can be by memory u ₁1/4th cycles of value displacement realize, i.e. u ₂=V _msin (ω ₀t+ θ ₀+ 90 °)=V _mcos (ω ₀t+ θ ₀), wherein V _mit is voltage magnitude.Further, establish $v_1=\sin ({\mathrm{\ω}}_{0}t+{\mathrm{\θ}}_0)=\frac{u_1}{V_m},v_2=\cos ({\mathrm{\ω}}_{0}t+{\mathrm{\θ}}_0)=\frac{u_2}{V_m},$ Wherein $V_m=\mathrm{LPF}\left(\sqrt{{u_1}^2+{u_2}^2}\right)$ By

obtain through low-pass filtering.At this structure

do respectively cross product

and and order ${\stackrel{\→}{V}}_0\×{\stackrel{\→}{U}}_q=a\stackrel{\→}{K},{\stackrel{\→}{V}}_0\×{\stackrel{\→}{U}}_d=b\stackrel{\→}{K}$ From cross product formula $a=\left|\right|{\stackrel{\→}{V}}_0\left|\right|\·\left|\right|{\stackrel{\→}{U}}_q\left|\right|\·\sin \mathrm{\α}=\sin \mathrm{\α},$ $b=\left|\right|{\stackrel{\→}{V}}_0\left|\right|\·\left|\right|{\stackrel{\→}{U}}_d\left|\right|\·\sin \mathrm{\β}=\sin \mathrm{\β}$

Will

be decided to be transverse axis

By β=ω t+ θ-ω ₀t-θ ₀=2 π t (f-f ₀)+(θ-θ ₀),

And f and f ₀differ very little (<5%) therefore α and β show as the DC quantity of low frequency pulsating, thereby can implement low-pass filtering to it, obtain a ₀=LPF (sin α), b ₀=LPF (sin β)

From a=sin α, in the time of sin α >0 be positioned at Left half-plane, otherwise RHP; From b=sin β, in the time of sin β >0

be positioned at poincare half plane, otherwise be positioned at lower half-plane.

Obtain state table below:

a 0	+	+	-	-
					b 0	+	-	-	+
U 1Position	Ⅰ	Ⅱ	Ⅲ	Ⅳ

If

be positioned at II, III quadrant, illustrates two vectorial wide aparts, therefore can be by

directly Rotate 180 °; If

be positioned at I quadrant, explanation

in advance should reduce

if

be positioned at IV quadrant, should strengthen

if

occur being continuously positioned at II, the situation of III quadrant, illustrates that off-grid or electrical network are abnormal.

For

regulated quantity δ, if the step-lengths such as employing should meet

preferably select

if adopt the step-length such as not, should make maximum step-length

to ensure that α converges to 0.

If

fall into for the second time II, III quadrant, should make regulated quantity δ double; Still invalid after doubling, prove that power network signal disappears or departs from allowed band.By

obtain

?

By iterative formula

obtain

right

do low-pass filtering, obtain

so far, realized the locking of diagonal frequencies and starting phase angle.

This algorithm is ensureing, under the prerequisite of equal phase-locked precision, to only have 1/3rd left and right of conventional PI algorithm operation time, for DSP has saved a large amount of calculation resources.On the DSP of the 32MIPS of Freescale, its time of implementation is less than 5 microseconds.

Claims (3)

1. the efficient BANG-BANG software phase-lock loop based on rotating coordinate system, is characterized in that, this software phase-lock loop is a kind of grid-connected phase-locked control algolithm for renewable energy source domain; In algorithm, construct a two-dimensional linear space being generated by (ω, θ), and chosen

wherein

with

can form one group of orthonormal basis; If line voltage angular frequency is ω ₀, initial phase angle is θ ₀, and voltage magnitude is V _m, can construct so a vector ${\stackrel{\&RightArrow;}{V}}_0=[\cos ({\mathrm{\&omega;}}_{0}t+{\mathrm{\&theta;}}_0),\sin ({\mathrm{\&omega;}}_{0}t+{\mathrm{\&theta;}}_0)];$ Do respectively cross product

$\begin{array}{c}{\stackrel{\&RightArrow;}{V}}_0\&times;{\stackrel{\&RightArrow;}{U}}_q=(\cos ({\mathrm{\&omega;}}_{0}t+{\mathrm{\&theta;}}_0)\stackrel{\&RightArrow;}{i}+\sin ({\mathrm{\&omega;}}_{0}t+{\mathrm{\&theta;}}_0)\stackrel{\&RightArrow;}{j})\&times;(\cos (\mathrm{\&omega;t}+\mathrm{\&theta;})\stackrel{\&RightArrow;}{i}+\sin (\mathrm{\&omega;t}+\mathrm{\&theta;})\stackrel{\&RightArrow;}{j})\\ =(\cos ({\mathrm{\&omega;}}_{0}t+{\mathrm{\&theta;}}_0)\sin (\mathrm{\&omega;t}+\mathrm{\&theta;})-\sin ({\mathrm{\&omega;}}_{0}t+{\mathrm{\&theta;}}_0)\cos (\mathrm{\&omega;t}+\mathrm{\&theta;}))\stackrel{\&RightArrow;}{k}\\ =\sin ((\mathrm{\&omega;}-{\mathrm{\&omega;}}_0)t+(\mathrm{\&theta;}-{\mathrm{\&theta;}}_0))\stackrel{\&RightArrow;}{k}\end{array}$

Cross product

$\begin{array}{c}{\stackrel{\&RightArrow;}{V}}_0\&times;{\stackrel{\&RightArrow;}{V}}_d=(\cos ({\mathrm{\&omega;}}_{0}t+{\mathrm{\&theta;}}_0)\stackrel{\&RightArrow;}{i}+\sin ({\mathrm{\&omega;}}_{0}t+{\mathrm{\&theta;}}_0)\stackrel{\&RightArrow;}{j})\&times;(-\sin (\mathrm{\&omega;t}+\mathrm{\&theta;})\stackrel{\&RightArrow;}{i}+\cos (\mathrm{\&omega;t}+\mathrm{\&theta;})\stackrel{\&RightArrow;}{j})\\ =(\cos ({\mathrm{\&omega;}}_{0}t+{\mathrm{\&theta;}}_0)\cos (\mathrm{\&omega;t}+\mathrm{\&theta;})+\sin ({\mathrm{\&omega;}}_{0}t+{\mathrm{\&theta;}}_0)\sin (\mathrm{\&omega;t}+\mathrm{\&theta;}))\stackrel{\&RightArrow;}{k}\\ =\cos ((\mathrm{\&omega;}-{\mathrm{\&omega;}}_0)t+(\mathrm{\&theta;}-{\mathrm{\&theta;}}_0))\stackrel{\&RightArrow;}{k}\end{array}$

And order

be a=sin ((ω-ω ₀) t+ (θ-θ ₀)),

b=cos((ω-ω ₀)t+(θ-θ ₀))

, according to a, the symbol of b can be determined

with

relative position relation; With

as transverse axis, as a coordinate system of longitudinal axis structure, if

be positioned at I, IV quadrant, regulates ω in BANG-BANG mode, implements a negative or positive angle increment and slows down or strengthen

angular velocity of rotation; If

be positioned at II, III quadrant, will

rotate 180 °,

follow the tracks of

realize soft phase-lockedly, realize a kind of grid-connected phase-locked control algolithm.

2. a kind of efficient BANG-BANG software phase-lock loop based on rotating coordinate system according to claim 1, wherein vector it is characterized in that:

vector can be constructed by following mode, and sinusoidal component is directly measured as u by line voltage ₁=V _msin (ω ₀t+ θ ₀), cosine component can obtain u by differential circuit ₂=V _mcos (ω ₀t+ θ ₀), or cosine component can be by memory u ₁1/4th cycles of value displacement realize, i.e. u ₂=V _msin (ω ₀t+ θ ₀+ 90 °)=V _mcos (ω ₀t+ θ ₀), wherein V _mit is voltage magnitude; Further, establish $v_1=\sin ({\mathrm{\&omega;}}_{0}t+{\mathrm{\&theta;}}_0)=\frac{u_1}{V_m},v_2=\cos ({\mathrm{\&omega;}}_{0}t+{\mathrm{\&theta;}}_0)=\frac{u_2}{V_m},$ Wherein $V_m=\mathrm{LPE}\left(\sqrt{{u_1}^2+{u_2}^2}\right),$ Thereby structure vector ${\stackrel{\&RightArrow;}{V}}_0=[v_2,v_1]=[\cos ({\mathrm{\&omega;}}_{0}t+{\mathrm{\&theta;}}_0),\sin ({\mathrm{\&omega;}}_{0}t+{\mathrm{\&theta;}}_0)].$

3. a kind of efficient BANG-BANG software phase-lock loop based on rotating coordinate system according to claim 1, wherein regulates realization by BANG-BANG

follow the tracks of

it is characterized in that: by a, b with

as transverse axis, as the quadrant location positioning a under a coordinate system of longitudinal axis structure, the symbol combination of b, thus determine with

position relationship; Regulate by BANG-BANG, even

in advance

be positioned at I quadrant, implement a negative angle increment and slow down

angular velocity of rotation, if in advance

be positioned at IV quadrant, implement a positive angle increment and strengthen

angular velocity of rotation, if

be positioned at II, III quadrant, will

rotate 180 °, can make

stably follow the tracks of fast,

thereby realize soft phase-locked.