CN103869145B - A kind of detection method of power network normal voltage and distorted voltage component - Google Patents

Abstract

The detection method of the technical field the invention belongs to improve the Active Power Filter-APF of the quality of power supply, more particularly to a kind of power network normal voltage and distorted voltage component.Step 1：The two orthogonal elements e of space M are set up by three-phase any period voltage signal_r(t) and e_i(t).Step 2：By two orthogonal elements e_r(t) and e_iT () carries out sliding-model control and obtains { e_r1……e_rNAnd { e_i1……e_iN}.Step 3：Backstepping is calculated and solves element e_rT () projectsWith element e_iT () projectsStep 4：ByWithObtain the instantaneous value of voltage positive-sequence component.Step 5：Distorted voltage component is obtained compared with initial voltage.Therefore, the invention has the advantages that：Can line voltage be distorted with it is asymmetric when, extract real-time standard three-phase voltage and distorted voltage component.

Description

A kind of detection method of power network normal voltage and distorted voltage component

Technical field

Technical field the invention belongs to improve the Active Power Filter-APF of the quality of power supply, more particularly to a kind of power network standard The detection method of voltage and distorted voltage component.

Background technology

In recent years, with the continuous appearance and the execution that deepens continuously of national energy-saving policy, the improvement of power quality problem is made It is a part for power network development strategy, has received more and more attention.

Active Power Filter-APF (Active Power Filter, APF) is asked as a kind of harmonic pollution in electric power net that effectively suppresses The equipment of topic, shows powerful vitality, receives the extensive concern of power electronics circle, and with correlation technique and reason The development of opinion, the research of APF makes great progress.And APF is mainly and carries out detection by the electric current to grid side and go forward side by side Row compensation, therefore, the detection of distortion current just turns into the basis of whole performance quality.In practice, system power quality Important evaluation index is exactly the voltage waveform and amplitude of common node.Therefore, it can be preferably distortion to set up standard voltage shape The detection of electric current provides reference signal with calculating, is based on the theoretical important content of waveform compensation and theoretical foundation.

The content of the invention

The present invention mainly solves the technical problem existing for prior art；Can occur in line voltage there is provided one kind abnormal When becoming and be asymmetric, a kind of power network normal voltage and distorted voltage point of extract real-time standard three-phase voltage and distorted voltage component The detection method of amount.

Above-mentioned technical problem of the invention is mainly what is be addressed by following technical proposals：

The detection method of a kind of power network normal voltage and distorted voltage component, based on defined below：Node three-phase voltage is u_a、u_b、u_cFor：

Wherein,It is the positive sequence voltage instantaneous value of k voltage signal of a phases, E_k-sin(kωt+θ_ek-) It is the k negative sequence voltage instantaneous value of voltage signal, E_k0sin(kωt+θ_ek0) it is the k residual voltage instantaneous value of voltage signal, together Reason b, c phases；

It is characterised in that it includes following steps：

Step 1, voltage signal orthogonal elements acquisition module sets up vector space M's based on three-phase any period voltage signal Two orthogonal elements e_r(t) and e_i(t)；Wherein, the vector that vector space M is made up of the symmetrical sine voltage signal of three-phase positive sequence Space；Can be by element e for the either element in vector space M_r(t) and e_i(t) linear expression, i.e. element e_r(t) and e_i T () is a Complete Orthogonal base of space M；

Wherein,

Step 2, orthogonal elements discrete processes module obtains step 1 voltage signal orthogonal elements acquisition module

The two orthogonal elements e for arriving_r(t) and e_iT () carries out sliding-model control and obtains { e_r1……e_rNAnd { e_i1……e_iN}；

Wherein, e_rj={ e_raje_rbje_rcj}

e_ij={ e_iaje_ibje_icj, j is any positive integer in 1~N；

Step 3, element projection process module obtains element e according to the sliding-model control result backstepping that step 2 is obtained_r(t) Projection U_rkWith element e_iT () projects U_ik；I.e.：

Step 4, the projection U obtained according to step 3 by instantaneous value processing module_rkWith projection U_ikObtain voltage positive-sequence component Instantaneous value；I.e.：

Wherein, u_1akIt is the instantaneous value of A phase voltage positive-sequence components, u_1bkIt is B phase voltages The instantaneous value of positive-sequence component, u_1ckIt is the instantaneous value of C phase voltage positive-sequence components；

Step 5, the instantaneous value of the voltage positive-sequence component that step 4 is obtained compares with initial voltage and obtains distorted voltage point Amount；I.e.：

Wherein, u_ackIt is the distorted voltage component of A phases, u_akIt is the initial voltage component of A phases, u_1akFor The instantaneous positive-sequence component of A phases；Similarly u_bck u_cck。

Therefore, the invention has the advantages that：Can line voltage be distorted with it is asymmetric when, extract real-time standard three Phase voltage and distorted voltage component.

Brief description of the drawings

Accompanying drawing 1 is the detection principle diagram of normal voltage of the invention and distorted voltage component.

Specific embodiment

Below by embodiment, and with reference to accompanying drawing, technical scheme is described in further detail.

Embodiment：

In APF devices, according to its structure, no matter using which kind of compensation, be intended in compensation process to be exchanged is active Power is minimum, and compensation point voltage differs minimum with rated voltage, and this is also to be controlled most most beneficial for APF DC capacitor voltages Good running status.If node three-phase voltage is u_a、u_b、u_cIt is represented by：

Wherein, E_k+It is k positive sequence harmonic amplitude, E_k-It is k Negative sequence harmonic amplitude, E_k0It is k Zero-pharse harmonic amplitude.

For the vector space X that three-phase any period voltage signal is constituted, its element：

With

Definition of inner product be

If the vector space that the symmetrical sine voltage signal of three-phase positive sequence is constituted is M, space M must be that the son of space X is empty Between.Element

With

The element of space M is, and both inner products are

Can be by element e for the either element in the M of space_r(t) and e_i(t) linear expression, i.e. element e_r(t) and e_iT () is One Complete Orthogonal base of space M.Harmonic wave, fundamental wave negative sequence and zero-sequence component and orthogonal basis in three-phase any period voltage waveform It is satisfied by formula (0.5).Therefore the fundamental positive sequence of space X either element u (t) is asked for, and is equivalent to ask element u (t) to exist Projection on the M of space.

The real time extracting method of standard voltage shape is as follows：Any phase voltage first passed through in three-phase sets up the two of space M Orthogonal elements e_r(t) and e_iT (), by it, discretization is obtained within a primitive period

{e_r1……e_rNAnd { e_i1……e_iN}

Wherein：

e_rj={ e_raj e_rbj e_rcj, e_ij={ e_iaj e_ibj e_icj}

When the centrifugal pump of system voltage u (t) for detecting is { u₁……u_N, wherein k=20, j=k-N, u_j={ u_aj u_bj u_cj, system voltage u (t) is now tried to achieve to element e_rT () projects U_rkRecurrence formula it is as follows：

System voltage u (t) is tried to achieve to element e_iT () projects U_ikRecurrence formula be

Can be in the hope of the instantaneous value of normal voltage by formula (0.6) and the formula of formula (0.7) two

Thus the instantaneous value that also can obtain voltage distortion component is

Specific embodiment described herein is only to the spiritual explanation for example of the present invention.Technology neck belonging to of the invention The technical staff in domain can be made various modifications or supplement to described specific embodiment or be replaced using similar mode Generation, but without departing from spirit of the invention or surmount scope defined in appended claims.

Claims (1)

1. the detection method of a kind of power network normal voltage and distorted voltage component, based on defined below：Node three-phase voltage is u_a、 u_b、u_cFor：

$\left\{\begin{array}{c}{u}_a=\underset{k=1}{\overset{\mathrm{\∞}}{\mathrm{\Σ}}}\[E_{k+}\sin \left(k\mathrm{\ω}t+{\mathrm{\θ}}_{ek+}\right)+E_{k-}\sin \left(k\mathrm{\ω}t+{\mathrm{\θ}}_{ek-}\right)+E_{k0}\sin \left(k\mathrm{\ω}t+{\mathrm{\θ}}_{ek0}\right)\]\\ u_b=\underset{k=1}{\overset{\mathrm{\∞}}{\mathrm{\Σ}}}\[E_{k+}\sin \left(k\mathrm{\ω}t+{\mathrm{\θ}}_{ek+}-2\mathrm{\π}/3\right)+E_{k-}\sin \left(k\mathrm{\ω}t+{\mathrm{\θ}}_{ek-}+2\mathrm{\π}/3\right)+E_{k0}\sin \left(k\mathrm{\ω}t+{\mathrm{\θ}}_{ek0}\right)\]\\ u_c=\underset{k=1}{\overset{\mathrm{\∞}}{\mathrm{\Σ}}}\[E_{k+}\sin \left(k\mathrm{\ω}t+{\mathrm{\θ}}_{ek+}+2\mathrm{\π}/3\right)+E_{k-}\sin \left(k\mathrm{\ω}t+{\mathrm{\θ}}_{ek-}-2\mathrm{\π}/3\right)+E_{k0}\sin \left(k\mathrm{\ω}t+{\mathrm{\θ}}_{ek0}\right)\]\end{array}\right.,$

Wherein, E_k+sin(kωt+θ_ek+) it is the positive sequence voltage instantaneous value of k voltage signal of a phases, E_k-sin(kωt+θ_ek-) it is k times The negative sequence voltage instantaneous value of voltage signal, E_k0sin(kωt+θ_ek0) it is the residual voltage instantaneous value of k voltage signal, similarly b, c Phase；

It is characterised in that it includes following steps：

Step 1, voltage signal orthogonal elements acquisition module is based on three-phase any period voltage signal and is setting up the two of vector space M just Hand over element e_r(t) and e_i(t)；Wherein, the vector space that vector space M is made up of the symmetrical sine voltage signal of three-phase positive sequence； Can be by element e for the either element in vector space M_r(t) and e_i(t) linear expression, i.e. element e_r(t) and e_iT () is sky Between M a Complete Orthogonal base；

Wherein,

$e_i\left(t\right)=\left\{\begin{array}{ccc}cos\mathrm{\ω}t& cos(\mathrm{\ω}t-\frac{2}{3}\mathrm{\π})& cos(\mathrm{\ω}t+\frac{2}{3}\mathrm{\π})\end{array}\right\}$

Step 2, two orthogonal elements that orthogonal elements discrete processes module obtains step 1 voltage signal orthogonal elements acquisition module e_r(t) and e_iT () carries out sliding-model control and obtains { e_r1……e_rNAnd { e_i1……e_iN}；

Wherein, e_rj={ e_raj e_rbj e_rcj}

e_ij={ e_iaj e_ibj e_icj, j is any positive integer in 1~N；

Step 3, element projection process module obtains element e according to the sliding-model control result backstepping that step 2 is obtained_rT () projectsWith element e_iT () projectsI.e.：

$\begin{array}{c}{\tilde{U}}_{rk}=\frac{1}{N}\underset{j=k-N}{\overset{k}{\mathrm{\Σ}}}\left(u_{aj}{e}_{raj}+u_{bj}{e}_{rbj}+u_{cj}{e}_{rcj}\right)\\ ={\tilde{U}}_{r\left(k-1\right)}+\left(u_{ak}{e}_{rak}+u_{bk}{e}_{rbk}+u_{ck}{e}_{rck}\right)-\left(u_{a\left(k-N-1\right)}{e}_{ra\left(k-N-1\right)}+u_{b\left(k-N-1\right)}{e}_{rb\left(k-N-1\right)}+u_{c\left(k-N-1\right)}{e}_{rc\left(k-N-1\right)}\right)\end{array}$

$\begin{array}{c}{\tilde{U}}_{ik}=\frac{1}{N}\underset{j=k-N}{\overset{k}{\Σ}}(u_{aj}{e}_{iaj}+u_{bj}{e}_{ibj}+u_{cj}{e}_{icj})\\ ={\tilde{U}}_{i(k-1)}+(u_{ak}{e}_{iak}+u_{bk}{e}_{ibk}+u_{ck}{e}_{ick})-(u_{a(k-N-1)}{e}_{ia(k-N-1)}+u_{b(k-N-1)}{e}_{ib(k-N-1)}+u_{c(k-N-1)}{e}_{ic(k-N-1)})\end{array}$

Step 4, the projection obtained according to step 3 by instantaneous value processing moduleAnd projectionObtain the wink of voltage positive-sequence component Duration；I.e.：

Wherein, u_1akIt is the instantaneous value of A phase voltage positive-sequence components, u_1bkIt is B phase voltage positive sequences The instantaneous value of component, u_1ckIt is the instantaneous value of C phase voltage positive-sequence components；

Step 5, the instantaneous value of the voltage positive-sequence component that step 4 is obtained compares with initial voltage and obtains distorted voltage component； I.e.：

Wherein, u_ackIt is the distorted voltage component of A phases, u_akIt is the initial voltage component of A phases, u_1akIt is A phases Instantaneous positive-sequence component；Similarly u_bck u_cck。