CN102118031A - Method for calculating instantaneous reactive power of power system based on vector recognition and SVC (static var compensator) compensation device - Google Patents

Abstract

The invention discloses a method for calculating the instantaneous reactive power of a power system based on vector recognition and an SVC (static var compensator) compensation device. The method comprises the following steps that: (1) a control system acquires the voltage of a three-phase system, the current of the three-phase system and the current instantaneous vale of the sine wave signal of the current of a transistor controlled reactor at each voltage zero passage moment; (2) the control system obtains the effective values of the real part and imaginary part of each sine variable by use of the current instantaneous value and the instantaneous value before 1/6 period in a vector recognition manner after each time of data acquisition; (3) the control system converts each sine variable to the same coordinate system according to Park conversion, and calculates the active component of active power and the active component of reactive power of each phase; and (4) the control system reduces the active component of the reactive power of each phase in a system bus by taking the active component of the reactive power of each phase as a compensation object of the SVC. The method disclosed by the invention has the advantages of simple calculation and the like, can be used for detecting three-phase reactive power in real time, and is convenient to use.

Description

Electric power system instantaneous reactive computational methods and SVC compensation arrangement based on vector identification

[technical field]

The present invention relates to a kind of electric power system instantaneous reactive computational methods and employed SVC compensation arrangement of this method based on vector identification.Belong to transmission system and power distribution system equipment Energy Saving Control field.

[background technology]

Along with power system development, the demand of reactive power being carried out quick dynamic compensation is increasing.Therefore the real-time detection of reactive power with calculate the key technology that has just become reactive power compensation.

From the pertinent literature analysis, at present the main technique methods of calculating at reactive power has: the instantaneous reactive theoretical method, based on fourier transform method, detect mode such as electric current and voltage phase difference, these modes respectively have pluses and minuses.The method real-time that detects the electric current and voltage phase difference is poor, can not adapt to the demand of quick dynamic compensation.Also need to gather the signal of half cycle based on fourier transform method, low-response, using has limitation.Can calculate reactive power, response in real time soon based on the instantaneous reactive theoretical method, therefore be widely used in the field of quick dynamic compensation, for example SVC, STATCOM, APF etc.Itself need use α β matrixing, park conversion scheduling algorithm in a large number but instantaneous reactive is theoretical, computational methods complexity, amount of calculation are very big.

[summary of the invention]

The present invention has overcome the deficiency of above-mentioned technology, provide a kind of and can detect three phase reactive power in real time, calculate the electric power system instantaneous reactive computational methods based on vector identification simple, easy to use again, provide this method employed SVC compensation arrangement simultaneously.

For achieving the above object, the present invention has adopted following technical proposal:

Electric power system instantaneous reactive computational methods based on vector identification comprise the steps:

The first step, control system are gathered the current instantaneous value of sine wave signal of three-phase system voltage, three-phase system electric current, transistor Controlled Reactor TCR electric current constantly at each voltage zero-cross;

Second step, will utilize instantaneous value before current instantaneous value and 1/6 cycle to obtain the real part and the imaginary part effective value of each sinusoidal variable by vectorial RM after each image data;

The 3rd goes on foot, according to the Park conversion each sinusoidal variable is converted under the same coordinate system, calculates the active power active constituent and the reactive power active constituent of every phase;

The 4th step, with every phase reactive power active constituent as the target compensation of reactive power compensator, reduce the reactive power active constituent of every phase in the system busbar.

Gather three-phase system voltage and three-phase system electric current by transformer T1.

A kind of SVC compensation arrangement, include transformer T1, the elementary three-phase input end of transformer T1 is connected on the three-phase bus of system under test (SUT), and the three-phase output end of T1 level of transformer inserts filter Filter, Thyristor Controlled Reactor TCR and electric load Load in turn.

Described filter Filter is made up of three electric capacity and three inductance, and an end of three electric capacity is connected with the three-phase output end of T1 level of transformer respectively, and the other end of three electric capacity is respectively by linking together behind three inductance.

Connect into ring-type after described Thyristor Controlled Reactor TCR is provided with by three thyristor groups and three inductance interval and form, each thyristor groups is made up of reverse parallel connection thyristor together, node between the head end of each thyristor groups and the tail end of each inductance is as the input of Thyristor Controlled Reactor TCR, and three inputs are connected with the three-phase output end of T1 level of transformer respectively.

Described electric load Load is three slide rheostats, and three slide rheostat one ends are connected with the three-phase output end of T1 level of transformer respectively, and three slide rheostat other ends link together.

The invention has the beneficial effects as follows:

1, the present invention compares with traditional in the past reactive power calculating mode, can detect three phase reactive power in real time, has again to calculate advantage simple, easy to use, and therefore using in reactive power compensation field large-scale popularization has crucial meaning.

2, adopt method of the present invention can improve power factor, reduce idle component, reduce line loss.

[description of drawings]

Fig. 1 is the structure chart of SVC compensation arrangement of the present invention.

[embodiment]

The present invention at first introduces the electric power system instantaneous reactive computational methods based on vector identification, comprises the steps:

The first step, control system are gathered the three-phase system voltage U constantly at each voltage zero-cross _a, U _b, U _c, the three-phase system electric current I _a, I _b, I _c, transistor Controlled Reactor TCR current i _Ab, i _Bc, i _CaThe current instantaneous value of sine wave signal; Totally 9 instantaneous values.Three-phase system voltage and three-phase system electric current are gathered by transformer T1.

Second step, will utilize instantaneous value before current instantaneous value and 1/6 cycle to obtain the real part and the imaginary part effective value of each sinusoidal variable by vectorial RM after each image data;

The 3rd goes on foot, according to the Park conversion each sinusoidal variable is converted under the same coordinate system, calculates the active power active constituent and the reactive power active constituent of every phase;

The 4th step, with every phase reactive power active constituent as the target compensation of reactive power compensator, reduce the reactive power active constituent of every phase in the system busbar.

Be example with a collection capacity v below, collection capacity v is in above-mentioned 9 instant values.Gather this 9 instantaneous value data constantly in every phase voltage zero passage, each cycle of three-phase system voltage has 6 zero passages constantly, and per 2 zero passages just differ 1/6 cycle constantly.Sampled value before this real-time sampling value of known each sine wave signal and 1/6 cycle can obtain each sine wave signal real part and imaginary part, and specific algorithm is as follows:

$\mathrm{tga}=\frac{v*\frac{\sqrt{3}}{2}}{v*\frac{1}{2}-v_{\mathrm{last}}}$

$\mathrm{Amp}\left(v\right)=\frac{\sqrt{v_{\mathrm{last}}^2+v^2-2*v_{\mathrm{last}}*v*0.5}}{\sqrt{3}/2}$

$\cos a=\frac{1}{\sqrt{{\mathrm{tga}}^2-1}}$

V wherein _LastIt is 1/6 sampled value before the cycle.Because sine wave signal is in one-period 0,2 π scope, tga has 2 numerical value, so need judge this v is in which scope according to relation between instantaneous sampling value v and the tangent angle tga.

If v＞0 and tga＜0, then v gets cosa=-cosa at second quadrant;

If v＜0 and tga＞0, then v gets cosa=-cosa at second quadrant;

If v _Last＜0 and tga=0, then v gets cos a=1 at 0 degree;

If v _Last＞0 and tga=0, then v gets cosa=-1 at 180 degree;

In other cases, cosa=cosa;

sina＝cosa*tga

So just calculated the real part and the imaginary part effective value of each sinusoidal variable, according to the Park conversion each sinusoidal variable being converted under the same coordinate system then is the coordinate system transverse axis with voltage vector Vab for example, calculates the real component and the idle component of every phase.The matrix of Park conversion is as follows

$\left[\begin{array}{c}p\\ q\end{array}\right]=\left[\begin{array}{cc}\sin \mathrm{\ωt}& -\cos \mathrm{\ωt}\\ -\cos \mathrm{\ωt}& -\sin \mathrm{\ωt}\end{array}\right]*\left[\begin{array}{c}\mathrm{\α}\\ \mathrm{\β}\end{array}\right]$

Because system power and line voltage-phase also differ 30 degree, therefore every phase real component and idle component are tried to achieve through following mode:

fsina_ab＝fsinIa*fcosVab-fcosIa*fsinVab

fcosa_ab＝fcosIa*fcosVab+fsinIa*fsinVab

fArray[0][0]＝fcosa_ab*0.866-fsina_ab*0.5

fArray[1][0]＝fsina_ab*0.866+fcosa_ab*0.5

freIa＝fAmpIa*fArray[0][0]

fimIa＝fAmpIa*fArray[1][0]

fsina_ab＝fsinIb*fcosVab-fcosIb*fsinVab

fcosa_ab＝fcosIb*fcosVab+fsinIb*fsinVab

fArray[2][0]＝fcosa_ab*0.866-fsina_ab*0.5

fArray[3][0]＝fsina_ab*0.866+fcosa_ab*0.5

freIb＝fAmpIb*fArray[2][0]

fimIb＝fAmpIb*fArray[3][0]

fsina_ab＝fsinIc*fcosVab-fcosIc*fsinVab

fcosa_ab＝fcosIc*fcosVab+fsinIc*fsinVab

fArray[4][0]＝fcosa_ab*0.866-fsina_ab*0.5

fArray[5][0]＝fsina_ab*0.866+fcosa_ab*0.5

freIc＝fAmpIc*fArray[0][0]

fimIc＝fAmpIc*fArray[1][0]

After trying to achieve each phase active power component of electric power system and reactive power component, with the target compensation of every phase reactive power active constituent as reactive power compensator.The present invention can improve power factor, reduces idle component, reduce line loss.

Secondly the present invention has introduced the employed SVC compensation arrangement of a kind of said method, include transformer T1, the elementary three-phase input end of transformer T1 is connected on the three-phase bus of system under test (SUT), and the three-phase output end of T1 level of transformer inserts filter Filter, Thyristor Controlled Reactor TCR and electric load Load in turn.

Described filter Filter is made up of three electric capacity and three inductance, and an end of three electric capacity is connected with the three-phase output end of T1 level of transformer respectively, and the other end of three electric capacity is respectively by linking together behind three inductance.

Connect into ring-type after described Thyristor Controlled Reactor TCR is provided with by three thyristor groups and three inductance interval and form, each thyristor groups is made up of reverse parallel connection thyristor together, node between the head end of each thyristor groups and the tail end of each inductance is as the input of Thyristor Controlled Reactor TCR, and three inputs are connected with the three-phase output end of T1 level of transformer respectively.

Described electric load Load is three slide rheostats, and three slide rheostat one ends are connected with the three-phase output end of T1 level of transformer respectively, and three slide rheostat other ends link together.

Claims (6)

1. based on the electric power system instantaneous reactive computational methods of vector identification, it is characterized in that comprising the steps:

The first step, control system are gathered the current instantaneous value of sine wave signal of three-phase system voltage, three-phase system electric current, transistor Controlled Reactor (TCR) electric current constantly at each voltage zero-cross;

Second step, will utilize instantaneous value before current instantaneous value and 1/6 cycle to obtain the real part and the imaginary part effective value of each sinusoidal variable by vectorial RM after each image data;

The 3rd goes on foot, according to the Park conversion each sinusoidal variable is converted under the same coordinate system, calculates the active power active constituent and the reactive power active constituent of every phase;

The 4th step, with every phase reactive power active constituent as the target compensation of reactive power compensator, reduce the reactive power active constituent of every phase in the system busbar.

2. the electric power system instantaneous reactive computational methods based on vector identification according to claim 1 is characterized in that gathering three-phase system voltage and three-phase system electric current by transformer (T1).

3. SVC compensation arrangement, it is characterized in that including transformer (T1), the elementary three-phase input end of transformer (T1) is connected on the three-phase bus of system under test (SUT), and the secondary three-phase output end of transformer (T1) inserts filter (Filter), Thyristor Controlled Reactor (TCR) and electric load (Load) in turn.

4. a kind of SVC compensation arrangement according to claim 3, it is characterized in that described filter (Filter) is made up of three electric capacity and three inductance, one end of three electric capacity is connected with the secondary three-phase output end of transformer (T1) respectively, and the other end of three electric capacity is respectively by linking together behind three inductance.

5. a kind of SVC compensation arrangement according to claim 3, it is characterized in that connecting into ring-type after described Thyristor Controlled Reactor (TCR) is provided with by three thyristor groups and three inductance interval and form, each thyristor groups is made up of reverse parallel connection thyristor together, node between the head end of each thyristor groups and the tail end of each inductance is as the input of Thyristor Controlled Reactor (TCR), and three inputs are connected with the secondary three-phase output end of transformer (T1) respectively.

6. a kind of SVC compensation arrangement according to claim 3, it is characterized in that described electric load (Load) is three slide rheostats, three slide rheostat one ends are connected with the secondary three-phase output end of transformer (T1) respectively, and three slide rheostat other ends link together.