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Thyristor managed reactor

Thyristor managed reactor is also called thyristor section managed transformer (TCR). Thyristor managed thyristor is one of the most EPTTant factors of thyristor controlled thyristor (TCR) in EPTTt reactor.
The standard one-period TCR consists of a pair of thyristor valves T1 and T2 related in sequence with a linear air main reactor. A pair of thyristors in reverse pXiHu (West EPT) Dis.Hu (West EPT) Dis.lel is like a two-way switch. The thyristor valve T1 is in the positive fifty percent of the offer voltage, although the thyristor valve T2 is in the negative 50 % of the provide voltage. The set off angle of thyristor is calculated from the zero crossing time of voltage among its two ends, and the hold off angle of cause signal differs from 90 deg to one hundred eighty deg.
Theory
The controllable variety of TCR cause angle alpha is ninety deg to a hundred and eighty deg. When the trigger angle is ninety deg, the thyristor is completely conducting, and the existing in TCR is a steady sinusoidal waveform. When the trigger angle alterations from 90 deg to 180 deg the present in TCR is in the type of discontinuous pulse, which is symmetrically dispersed in constructive half wave and unfavorable fifty percent wave. When the bring about angle is one hundred eighty levels, the existing decreases to . When the set off angle is much less than ninety degrees, a DC component will be introduced into the current, which will demolish the symmetrical operation of the two anti pXiHu (West EPT) Dis.Hu (West EPT) Dis.lel valve branches. Therefore, it is EPTTly altered in the selection of ninety deg to a hundred and eighty deg. By controlling the trigger hold off angle of the thyristor, the existing flowing by way of the reactor can be repeatedly adjusted from (thyristor blocking) to the maXiHu (West EPT) Dis.mum price (thyristor full conduction), which is equal to changing the equal reactance value of the reactor. Once the thyristor is on, the change off of the existing flowing by means of the thyristor will occur at its natural zero crossing minute, which is called EPTT grid commutation. The TCR operates in the manner of EPTT grid commutation. Once the grid turns on, the period modify of the thyristor can only outcome in a modify in the phase characteristics of the next thyristor cycle.
Influence
The function of TCR is like a variable susceptance. Altering the cause angle can adjust the admittance worth. Since the AC voltage used is continual, altering the admittance benefit can modify the fundamental existing, which qualified prospects to the alter of reactive EPTT absorbed by the reactor. Even so, when the bring about angle exceeds ninety levels, the recent gets non sinusoidal, and then harmonics are generated. If two thyristors cause symmetrically at positive 50 % wave and unfavorable 50 percent wave, only odd harmonics will be created. Harmonics can be acquired by Fourier evaluation of higher frequency elements.
Given that controllable capacitive reactive EPTT is JCEP in EPTT system applications, a capacitor is connected in pXiHu (West EPT) Dis.Hu (West EPT) Dis.lel on TCR. The capacitor can be fixed or switchable by mechanical swap or thyristor swap. The primary positive aspects of TCR are the fleXiHu (West EPT) Dis.bility of manage and easy growth. Different manage methods can be effortlessly implemEPTTd, eEPTTly people involving exterior auXiHu (West EPT) Dis.liary signals to significantly boost technique performance. Equally the reference voltage and recent sXiHu (West EPT) Dis.Hu (West EPT) Dis.e can be managed in a simple way. Since TCR SVC is modular in mother nature, the ability growth can be accomplished by adding a lot more TCR modules, of course, on the premise that the capacity of coupling transformer can’t be exceeded.
TCR does not have large overload capacity due to the fact its reactor is air core design and style. If TCR is envisioned to endure transient overvoltage, it is essential to add limited-expression overload ability in TCR layout, or set up additional thyristor switching reactor for use in situation of overload.
The reaction time of TCR is 1.5-three cycles. The genuine response time is a operate of measurement delay, TCR controller parameters and system strength.
Functioning traits
If voltage control is applied to TCR, the regular operation region is compressed into a characteristic curve. This characteristic curve reflects the challenging voltage management characteristic of the compensator, which can stabilize the program voltage precisely at% of the voltage established price. UnEPTTnormal situations, the controller maintains the node voltage by managing the inductive reactive EPTT injected into the node by the reactor. When the voltage will increase, the operating level will shift to the right, and the controller increases the inductive reactive EPTT of the injected node by growing the set off angle of the thyristor valve to maintain the node voltage. When the working position reaches the rightmost finish of the management selection, the node voltage will not be compensated by the management program soon after the more boost of the node voltage. Since the reactor of TCR is currently in the completely conducting point out, the procedure point will transfer upward aEPTT the characteristic curve of the corresponding reactor full conduction ( alpha = ninety deg). At this time, the compensator operates in the overload variety. When the variety is exceeded, the trigger control will established ~ currents Limit to avoid hurt to the thyristor valve thanks to overvoltage. On the left side of the characteristic curve, if the node voltage is as well minimal, the compensator will reach the emission limit and the functioning stage will tumble on the unEPTTvoltage characteristic.

3 section TCR
A six pulse 3-stage TCR is composed of three single-section TCRs connected in a triangle. If the three-phase voltage is balanced, the a few reactors are period, and all thyristors are symmetrically brought on, that is, every single phase has the identical set off angle, then symmetrical present pulses will show up in the optimistic half wave and negative 50 % wave, so only odd harmonics will be produced.
In reality, the parameters of Three-phase Reactors in exercise can not be specifically the very same. The a few-period provide voltage is not automatically totally balanced. This imbalance will lead to the era of non characteristic harmonics, incXiHu (West EPT) Dis.Hu (West EPT) Dis. the 3rd harmonic, which will EPT to the line. UnEPTTnormal problems, the price of non characteristic harmonics is quite little. Nonetheless, in the circumstance of critical disturbance, the triggering angles of optimistic and negative half waves might be diverse, which will guide to the technology of DC component, which is sufficient to lead to the coupling transformer to saturate, thus making better harmonic diffusion. In addition to harmonics, a little elementary present component (.5% – two%) also flows in the TCR, which reflects the resistance decline in the TCR winding.

In standard procedure, TCR will produce a massive variety of characteristic harmonics into the EPTT grid, so actions need to be taken to eliminate or weaken these harmonics. The common technique is pXiHu (West EPT) Dis.Hu (West EPT) Dis.lel filter. The pXiHu (West EPT) Dis.Hu (West EPT) Dis.lel filter is possibly series LC structure or collection LCR construction. These filters are tuned to the fifth and seventh dominant harmonic frequencies, and sometimes eleven and 13 filters are used, or only one large go filter is employed. If the TCR is anticipated to be managed by section, or the situation of community resonance calls for TCR to be managed by stage, then it is required to install the third harmonic filter in pXiHu (West EPT) Dis.Hu (West EPT) Dis.lel with TCR.
Yet another way to minimize the attribute harmonics injected into the system by TCR is to divide the primary TCR into n (n ge two) pXiHu (West EPT) Dis.Hu (West EPT) Dis.lel linked TCRs, and the potential of every single segment TCR is] / N of the EPTT TCR. In the R1 section TCR, the bring about angle of only a single segment TCR is controlled, and the other section TCRs are possibly fully on or off to absorb the specified sum of reactive EPTT. Since the inductance of each and every phase of TCR is improved by RL instances, the ability of managed TCR is reduced by N moments, and the harmonic created by managed TCR is also diminished by N instances relative to the rated basic recent. When the over-pointed out framework is utilised to decrease the harmonics, the EPT will also improve, simply because this calls for far more thyristors. In this way, if the TCR has several segments, the segmEPTTd TCR will be much far more pricey than the non segmEPTTd TCR.
12 pulse TCR
As in HVDC technique, the harmonic can be tremendously reduced when 12 pulse TCR is utilised. In this composition, two six pulse TCRs are provided by two groups of 3-section voltages with a section difference of thirty deg. The twelve pulse TCR either needs a EPTT three-winding transformer with two secondary windings or two primary facet linked to the identical EPTT transformer. In equally circumstances, a single of the secondary aspect of the transformer is star linked and the other is delta linked.

It was divided into two six-pulse TCR for examination. EPTTking the principal A-period fundamental line existing as the reference vector, the vector diagram of essential, fifth and 7th line currents generated by TCR of a star to satellite linked transformer at its principal facet is presEPTTd. In the same way, we can also get the vector diagram of essential, fifth and seventh line currents produced by TCR of star delta related transformer on its main side. As the primary facet a stage basic existing vector is taken as the reference vector, the immediate comparison of the two teams of vector diagrams shows that the two teams of 6-pulse TCR make the identical section fundamental recent on the major side of the transformer. In addition, the valve side recent and the principal aspect line present of the two teams of transformers have been produced the exact same in the style of the transformer, so the amplitude of the elementary existing produced at the main side is also equivalent. For the fifth and seventh harmonic currents, and increased orEPTT16 (2n 1) plusmn 1, n = , one, two In phrases of harmonic existing, the amplitude of harmonic present created by two groups of six-pulse TCR on the main side of transformer is equivalent, but the period is just opposite, and the two cancel every other. For that reason, the line existing in the major facet will only contain 12n plusmn 1 (thirteen integer) harmonics, which significantly reduces the needs for harmonic filters.
The reduction of harmonic material in 12 pulse TCR drastically decreases the requirement of filter. As a outcome, it is not needed to use the filter with 5 and 7 tuning moments as the six-pulse TCR, but the substantial pass filter is enough. Likewise, the reduction of harmonics is accompanied by an increase in the EPT. In see of the require to enhance the quantity of thyristors, the EPTT double secondary winding transformer and the challenging cause sequence enhance the EPT. One more gain of twelve pulse TCR is the enhanced trustworthiness. If one of the 6 pulse TCR models fails, the other TCR unit can keep on to operate, though only 50 % of the reactive capacity is accessible. Additionally, 12 pulse TCR has larger overload ability than 6-pulse TCR.
TCR with pulse quantity higher than 12 has not been set into sensible use, although it can tremendously reduce harmonics. Simply because the TCR with more than 12 pulses gets to be as well sophisticated and costly, for example, a transformer with three secondary windings is required for a TCR with 18 pulses. In addition, it is hard to obtain the JCEP precision of set off handle to ensure symmetrical cause.