CN103094907A - Control algorithm of static var generator based on virtual flux linkage direct control technology - Google Patents

Abstract

The invention relates to a control algorithm of static var generator based on virtual flux linkage direct control technology. The control algorithm of static var generator based on the virtual flux linkage direct control technology includes the following steps. Firstly, direct current lateral voltage is sampled and a periodic average value is obtained. Secondly, proportion integral transformation is performed on the voltage and active lost current amplitude is obtained. Thirdly, an active lost current is multiplied with the voltage to obtain an active power reference value and a system lateral reactive power reference value is zero. Fourthly, a real reactive power and a lost active power of a converter are worked out through the virtual flux linkage technology and the real power and the reference value are compared in a hysteresis mode. A switch instrument is used for directly controlling on-off of the converter and achieves reactive compensation for the load. The virtual flux linkage technology is used for obtaining instant active power and instant reactive power. A control grid and the converter respectively provide the active power and the reactive power in a corresponding mode to achieve the effect of compensation management.

Description

Static reacance generator control algolithm based on the direct control technology of virtual magnetic linkage

Technical field

The present invention relates to a kind of static reacance generator control algolithm based on the direct control technology of virtual magnetic linkage, belong to Automation of Electric Systems product and Power Quality Detection thereof, control technology field.

Background technology

In reply new energy development and electric power system scale constantly enlarge HVDC Transmission Technology, but current conversion station adopts the cut-off devices such as IGBT, IGCT to consist of the current conversion station high voltage direct current transmission, to passive mains supply, have advantages of that flexible load disturbance and independent regulation two ends are idle.In the control algolithm of such current transformer, based on virtual magnetic linkage theory, meritorious and reactive power are directly controlled and adjusted, can keep easily the stable of direct voltage and system frequency, control based on the alternating voltage feedback, idle by regulating, improving the quality of power supply and Systems balanth, is a kind of good direct Power Control algorithm of current transformer.

Along with the development of power electronic technology, various uses non-linear, impact equipment have brought a large amount of harmonic pollutions to electrical network, bring thus power factor low, and harmonic pollution is serious, and the problem such as system loss increasing.The FACTS equipment of various reactive power compensations and harmonic wave control arises at the historic moment.The compensation performance of the reactive-load compensation equipments such as static reacance generator is decided by the detection method of reactive current and the control of offset current, and current detection method and control algolithm face the problems such as bad dynamic performance, amount of calculation is large, engineering feasibility is less.It has its source in and has adopted instantaneous reactive power theory and related detecting method, or needs complicated hardware circuit, or needs loaded down with trivial details mathematical computations.

From the instantaneous meritorious angle of transmitting current transformer with quadergy, to keep DC-side Voltage Stabilization and to regulate reactive power as the control target of system, in conjunction with the virtual magnetic linkage direct Power Control and the reactive power adjustment technology that adopt in the direct current transportation current transformer, can make the control algolithm of administering harmonic wave and compensating reactive power equipment more directly perceived, quick, easy.

Summary of the invention

technique effect of the present invention can overcome defects, a kind of static reacance generator control algolithm based on the direct control technology of virtual magnetic linkage is provided, detect and control algolithm hardware realization complexity for traditional static reacance generator, need to carry out a large amount of mathematical operations, affect the shortcoming of system real time, the present invention is from instantaneous meritorious angle and dc capacitor voltage fluctuation and the generation active loss principle of transmitting system with quadergy, with the meritorious energy of regulating the electrical network input with keep the dc voltage bus to stabilize to the control target of system, the direct control technology of virtual magnetic linkage is proposed.

For achieving the above object, the present invention adopts following technical scheme: it comprises the steps:

(1) to the dc voltage sampling, get its cycle mean value;

(2) this voltage is carried out the proportional integral conversion, obtain the active loss current amplitude;

(3) active loss electric current and voltage multiply each other and obtain the active power reference value, and the system side reactive power reference qref is zero;

(4) consume active power by the actual reactive power of virtual magnetic linkage technique computes system and current transformer, actual power and reference value are carried out stagnant chain rate, directly control the realization of converter switches state to the reactive power compensation of load by switch list.

Obtain instantaneous gaining merit with idle by virtual magnetic linkage technology, control electrical network and current transformer corresponding active power and reactive power is provided respectively, reach the compensation regulation effect.Adopt the direct Power Control technology can make current transformer have High Power Factor, low THD, algorithm and control simple advantage, the instant idle and harmonic compensation that solves load.

The direct control technology of virtual magnetic linkage has following characteristics:

(1) can control fast independently respectively active power and reactive power, keep the stable of dc voltage and system side frequency.

(2) value of alternating current, alternating voltage and the direct voltage by measuring current transformer and utilize virtual flux linkage model directly to control the size of through-put power has amount of calculation little, and algorithm is directly perceived, the advantage that is easy to realize.

Description of drawings

Fig. 1 is the converter topologies figure of static reacance generator;

Fig. 2 is that the input space is divided 12 sector vectograms;

Fig. 3 is for adopting virtual magnetic linkage direct control-algorithm block diagram;

Fig. 4 is the logic switch table.

Embodiment

Fig. 1 is the PWM converter topologies that static reacance generator uses, and according to the PWM control law, effectively compensate System Reactive Power electric current or harmonic current, and it is constant that the dc capacitor voltage of current transformer just must keep.But dc capacitor voltage fluctuates, and the variation of dc voltage can be caused by two parts: the reactive power exchange of DC side and AC and the loss power of compensation arrangement i.e. meritorious exchange.The voltage fluctuation of capacitor that reactive power causes, but its integration in one-period is zero; Can consumed energy but power electronic device is cut-off inevitably, the existence of active power consumes the energy that stores on electric capacity, makes capacitance voltage constantly descend.

The control target of pwm converter is to make system power that the active current of load and the active currents such as loss of compensation arrangement are provided, and the electric current that compensation arrangement sends is reactive current and the harmonic current of system.

For stable DC side voltage, and the reactive power of dynamic compensation load, the present invention adopts and regulates respectively for system's instantaneous active power and reactive power based on the direct Power Control algorithm of virtual magnetic linkage.

The virtual motor of the Objective Concept of virtual magnetic linkage hypothesis is drawn, and can think the line voltage U _ab, U _bcAnd U _caBe by generation that virtual magnetic linkage is responded to, satisfy

Wherein

$U_L=\left(\begin{array}{c}{U}_{\mathrm{L\α}}\\ U_{\mathrm{L\β}}\end{array}\right)=\sqrt{\frac{2}{3}}\left(\begin{array}{cc}1& \frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}\end{array}\right)\left(\begin{array}{c}{U}_{\mathrm{ab}}\\ U_{\mathrm{bc}}\end{array}\right)---\left(1\right)$

Similarly, for current i _L:

$i_L=\left(\begin{array}{c}{i}_{\mathrm{L\α}}\\ i_{\mathrm{L\β}}\end{array}\right)=\sqrt{\frac{2}{3}}\left(\begin{array}{cc}\frac{3}{2}& 0\\ \frac{\sqrt{3}}{2}& \sqrt{3}\end{array}\right)\left(\begin{array}{c}{i}_a\\ i_b\end{array}\right)---\left(2\right)$

Come instantaneous active power and the reactive power of computing system by setting up virtual flux linkage model

Direct Power Control has possessed High Power Factor, low THD, algorithm and has controlled the advantages such as simple.The employing direct Power Control is regulated respectively for instantaneous active power and the reactive power of FACTS system.

The direct Power Control strategy is generally by adopting logic switch table (as shown in Figure 4), simultaneously to instantaneous meritorious and idle the adjusting.With instantaneous active power p and p _ref± H _pAnd instantaneous reactive power q and q _ref± H _qCompare, send into the power hysteresis comparator, output signal S _pAnd S _q, determine according to following rule:

$S_p=\left\{\begin{array}{cc}1& p<p_{\mathrm{ref}}-H_p\\ 0& p>p_{\mathrm{ref}}+H_p\end{array}\right.---\left(4\right)$

$S_q=\left\{\begin{array}{cc}1& q<q_{\mathrm{ref}}-H_q\\ 0& q>q_{\mathrm{ref}}+H_q\end{array}\right.---\left(5\right)$

Wherein, H _pRing width for the active power hysteresis comparator; H _qRing width for the reactive power hysteresis comparator.

In order to guarantee direct voltage U _dcGuarantee to stablize p _RefrDetermined by the DC voltage control feedback loop:

p _refr＝V _dcr∫(U _{dc_refr}-U _dcr)dt (6)

For reaching the full remuneration target, guarantee that the system side power factor is 1, q _RefiValue zero.

Switch list is according to S _p, S _qDetermine the needed on off state of system, i.e. s with θ _a, s _bAnd s _cValue, wherein

According to

N=1,2 ..., 12, determine θ is at which θ _nScope in.As shown in Figure 2.

According to S _p, S _qWith θ at which θ _nThree signals in scope can determine s according to switch list _a, s _bAnd s _cValue, s _as _bs _c=000～111, corresponding to U ₀～U ₇Zero vector is set is in order to reduce the switch on and off number of times and to make load and power supply does not carry out energy exchange.

Fig. 3 is for adopting virtual magnetic linkage direct control-algorithm block diagram, and is at first constant for keeping capacitance voltage, introduces current transformer DC side direct voltage as negative feedback.Passing ratio integral element obtains the active current amplitude, and the product of active current and direct voltage is active power reference value p _Refr, simultaneously in order to make system reach power factor near 1, with q _RefiBe made as 0, carry out stagnant chain rate with active loss power and the System Reactive Power power of real-time detection, calculating, gained output directly determines by switch list the conducting state that current transformer is required, realizes to the direct control of active power with to the adjustment of reactive power, immediately realizes the reactive power compensation of loading.It should be understood that multiple modification, modification and additional embodiment are all possible, so within the embodiment of all modification, modification will regard the protection range that is in the present patent application as.

Before this method, system and material description should be understood the disclosure and be not limited to described ad hoc approach opinion, system and material, because these may change.Be understood that equally the term that uses in specification just for specific scheme and embodiment are described, does not limit to the limited field of this explanation.

Claims (1)

1. the static reacance generator control algolithm based on the direct control technology of virtual magnetic linkage, is characterized in that, comprises the steps:

(1) to the dc voltage sampling, get its cycle mean value;

(2) this voltage is carried out the proportional integral conversion, obtain the active loss current amplitude;

(3) active loss electric current and voltage multiply each other and obtain the active power reference value, and the system side reactive power reference qref is zero;

(4) consume active power by the actual reactive power of virtual magnetic linkage technique computes system and current transformer, actual power and reference value are carried out stagnant chain rate, directly control the realization of converter switches state to the reactive power compensation of load by switch list.

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