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Thyristor managed reactor

Thyristor controlled reactor is also named thyristor period controlled transformer (TCR). Thyristor managed thyristor is a single of the most EPTTant factors of thyristor managed thyristor (TCR) in EPTTt reactor.
The standard single-period TCR is composed of a pair of thyristor valves T1 and T2 linked in series 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 swap. The thyristor valve T1 is in the good 50 % of the source voltage, while the thyristor valve T2 is in the adverse fifty percent of the source 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 set off sign varies from 90 deg to 180 deg.
Basic principle
The controllable assortment of TCR cause angle alpha is ninety deg to 180 deg. When the trigger angle is 90 deg, the thyristor is fully conducting, and the existing in TCR is a steady sinusoidal waveform. When the cause angle alterations from ninety deg to one hundred eighty deg the present in TCR is in the sort of discontinuous pulse, which is symmetrically distributed in constructive half wave and damaging half wave. When the bring about angle is one hundred eighty levels, the present decreases to . When the trigger angle is significantly less than ninety levels, a DC part will be introduced into the existing, which will wipe out the symmetrical procedure of the two anti pXiHu (West EPT) Dis.Hu (West EPT) Dis.lel valve branches. As a result, it is EPTTly adjusted in the assortment of ninety deg to a hundred and eighty deg. By controlling the set off hold off angle of the thyristor, the recent flowing by way of the reactor can be repeatedly adjusted from (thyristor blocking) to the maXiHu (West EPT) Dis.mum value (thyristor full conduction), which is equivalent to modifying the equivalent reactance value of the reactor. After the thyristor is on, the turn off of the current flowing by means of the thyristor will happen at its all-natural zero crossing instant, which is known as EPTT grid commutation. The TCR operates in the mode of EPTT grid commutation. When the grid turns on, the phase modify of the thyristor can only result in a alter in the period traits of the following thyristor cycle.
Effect
The part of TCR is like a variable susceptance. Altering the bring about angle can alter the admittance price. Since the AC voltage used is consistent, altering the admittance worth can modify the essential present, which prospects to the alter of reactive EPTT absorbed by the reactor. Nonetheless, when the set off angle exceeds ninety degrees, the existing becomes non sinusoidal, and then harmonics are generated. If two thyristors trigger symmetrically at constructive fifty percent wave and negative half wave, only odd harmonics will be produced. Harmonics can be acquired by Fourier examination of increased frequency elements.
Since controllable capacitive reactive EPTT is JCEP in EPTT technique purposes, a capacitor is linked in pXiHu (West EPT) Dis.Hu (West EPT) Dis.lel on TCR. The capacitor can be fastened or switchable by mechanical swap or thyristor swap. The principal advantages of TCR are the fleXiHu (West EPT) Dis.bility of manage and straightforward growth. Diverse handle methods can be easily implemEPTTd, eEPTTly those involving external auXiHu (West EPT) Dis.liary alerts to significantly enhance program functionality. Equally the reference voltage and current sXiHu (West EPT) Dis.Hu (West EPT) Dis.e can be controlled in a basic way. Simply because TCR SVC is modular in character, the capability enlargement can be attained by adding more TCR modules, of program, on the premise that the capability of coupling transformer can’t be exceeded.
TCR does not have massive overload potential because its reactor is air main style. If TCR is envisioned to withstand transient overvoltage, it is necessary to insert quick-expression overload capacity in TCR design and style, or set up further thyristor switching reactor for use in case of overload.
The reaction time of TCR is one.five-3 cycles. The genuine response time is a operate of measurement delay, TCR controller parameters and technique toughness.
Operating characteristics
If voltage control is used to TCR, the standard operation region is compressed into a attribute curve. This characteristic curve displays the tough voltage handle attribute of the compensator, which can stabilize the method voltage properly at% of the voltage set price. UnEPTTnormal situations, the controller maintains the node voltage by controlling the inductive reactive EPTT injected into the node by the reactor. When the voltage raises, the functioning position will shift to the proper, and the controller boosts the inductive reactive EPTT of the injected node by growing the set off angle of the thyristor valve to sustain the node voltage. When the running position reaches the rightmost end of the handle selection, the node voltage will not be compensated by the control technique following the additional improve of the node voltage. Due to the fact the reactor of TCR is previously in the completely conducting point out, the operation position will move upward aEPTT the characteristic curve of the corresponding reactor entire conduction ( alpha = ninety deg). At this time, the compensator operates in the overload selection. When the selection is exceeded, the cause control will established ~ currents Limit to stop injury to the thyristor valve owing to overvoltage. On the left facet of the characteristic curve, if the node voltage is too lower, the compensator will attain the emission limit and the working position will fall on the unEPTTvoltage attribute.

3 stage TCR
A 6 pulse three-section TCR consists of a few one-phase TCRs connected in a triangle. If the a few-section voltage is well balanced, the 3 reactors are stage, and all thyristors are symmetrically triggered, that is, each section has the very same trigger angle, then symmetrical recent pulses will seem in the optimistic half wave and adverse fifty percent wave, so only odd harmonics will be generated.
In fact, the parameters of Three-stage Reactors in follow can not be specifically the very same. The a few-period provide voltage is not essentially completely well balanced. This imbalance will lead to the era of non attribute harmonics, incXiHu (West EPT) Dis.Hu (West EPT) Dis. the third harmonic, which will EPT to the line. UnEPTTnormal circumstances, the benefit of non attribute harmonics is really little. Nonetheless, in the case of critical disturbance, the triggering angles of positive and adverse fifty percent waves may possibly be diverse, which will direct to the era of DC ingredient, which is adequate to cause the coupling transformer to saturate, hence generating increased harmonic diffusion. In addition to harmonics, a modest elementary present ingredient (.five% – 2%) also flows in the TCR, which reflects the resistance loss in the TCR winding.

In typical procedure, TCR will make a large quantity of attribute harmonics into the EPTT grid, so steps have to be taken to eliminate or weaken these harmonics. The typical approach is pXiHu (West EPT) Dis.Hu (West EPT) Dis.lel filter. The pXiHu (West EPT) Dis.Hu (West EPT) Dis.lel filter is either sequence LC structure or series LCR construction. These filters are tuned to the fifth and seventh dominant harmonic frequencies, and occasionally 11 and 13 filters are utilized, or only one substantial go filter is employed. If the TCR is expected to be controlled by section, or the issue of community resonance requires TCR to be managed by stage, then it is required to set up the 3rd harmonic filter in pXiHu (West EPT) Dis.Hu (West EPT) Dis.lel with TCR.
An additional way to decrease the characteristic harmonics injected into the system by TCR is to divide the main TCR into n (n ge two) pXiHu (West EPT) Dis.Hu (West EPT) Dis.lel connected TCRs, and the capacity of each and every section TCR is] / N of the EPTT TCR. In the R1 section TCR, the set off angle of only 1 section TCR is managed, and the other section TCRs are both totally on or off to soak up the specified quantity of reactive EPTT. Simply because the inductance of every section of TCR is elevated by RL moments, the potential of managed TCR is reduced by N times, and the harmonic produced by managed TCR is also diminished by N instances relative to the rated fundamental existing. When the over-mentioned construction is utilized to reduce the harmonics, the EPT will also boost, because this requires far more thyristors. In this way, if the TCR has a lot of segments, the segmEPTTd TCR will be significantly much more costly than the non segmEPTTd TCR.
twelve pulse TCR
As in HVDC program, the harmonic can be tremendously diminished when twelve pulse TCR is utilized. In this framework, two six pulse TCRs are equipped by two teams of a few-phase voltages with a phase big difference of thirty deg. The twelve pulse TCR either needs a EPTT three-winding transformer with two secondary windings or two principal facet related to the exact same EPTT transformer. In the two circumstances, one particular of the secondary aspect of the transformer is star connected and the other is delta connected.

It was divided into two 6-pulse TCR for examination. EPTTking the major A-section elementary line recent as the reference vector, the vector diagram of essential, fifth and seventh line currents produced by TCR of a star to satellite connected transformer at its primary facet is presEPTTd. Equally, we can also get the vector diagram of elementary, fifth and 7th line currents created by TCR of star delta related transformer on its major side. As the primary aspect a stage fundamental recent vector is taken as the reference vector, the direct comparison of the two teams of vector diagrams demonstrates that the two groups of six-pulse TCR create the same section essential existing on the principal aspect of the transformer. In addition, the valve side current and the primary aspect line recent of the two groups of transformers have been produced the identical in the design of the transformer, so the amplitude of the essential current generated at the major facet is also equivalent. For the fifth and seventh harmonic currents, and greater orEPTT16 (2n one) plusmn 1, n = , one, two In phrases of harmonic present, the amplitude of harmonic present generated by two groups of six-pulse TCR on the primary aspect of transformer is equivalent, but the phase is just reverse, and the two terminate every other. For that reason, the line recent in the primary side will only contain 12n plusmn one (13 integer) harmonics, which significantly lowers the requirements for harmonic filters.
The reduction of harmonic material in twelve pulse TCR tremendously lowers the prerequisite of filter. As a outcome, it is not necessary to use the filter with five and seven tuning moments as the 6-pulse TCR, but the substantial move filter is sufficient. Similarly, the reduction of harmonics is accompanied by an increase in the EPT. In see of the require to boost the amount of thyristors, the EPTT double secondary winding transformer and the complex set off sequence increase the EPT. Another gain of twelve pulse TCR is the improved trustworthiness. If 1 of the six pulse TCR units fails, the other TCR device can carry on to run, despite the fact that only half of the reactive capacity is available. In addition, 12 pulse TCR has larger overload ability than six-pulse TCR.
TCR with pulse amount greater than 12 has not been put into sensible use, though it can drastically lessen harmonics. Since the TCR with much more than 12 pulses turns into also complex and expensive, for example, a transformer with 3 secondary windings is required for a TCR with eighteen pulses. In addition, it is tough to obtain the JCEP precision of cause handle to ensure symmetrical set off.