Design et futur interruptorum circuituum directi medii voltus solidi-statorum

Quomodo operantur disjunctores solidi statis mediis tensibus:
Disjunctores DC solidi statis utuntur semiconductore potenti ad interrumpendum currentem defectus. Simplex topologia disjunctoris DC solidi status ostenditur in Figura 1. Quattuor diodes et IGCT repraesentant principalem viam conductionis, dum absorber surgorum utitur ad deponendum inductivitatis lineae casu defectus. Quando disjunctor DC excitat, IGCT desinit. Propter energiam inductive conservatam, voltus trans semiconductores celeriter crescit et absorber surgorum incipit ducere currentem. Ut deponatur inductivitas lineae, protectio voltus absorberis surgorum debet esse altior quam nominale voltus rete. Etiam oportet ut semiconductores potentes sustineant protectionem voltus absorberis surgorum. Principale praebet solidi status disjunctoris DC celeritas interruptionis et absens partes motiles. Cum semiconductores potentes collocati sunt in principali via conductionis, occurrunt on-state perditiones.

Figura 1: Simplificata designatio disjunctoris circuiti solidi status

Disjunctores circuiti solidi status solummodo dependunt ab interruptore solidi status ad portandum nominalem onus et ad interrumpendum currentem. Cum arcus electricus eliminatus est, alia machina necessaria est ad dissipandum conservatam energiam in inductivitate circuiti. Hoc saepe perficitur per varistor metal-oxidis (MOV) paralleliter connectum. MOV habet characteristicam non-linearem voltus/currentis.
Sua resistentia permanet alta (effectu agendo tamquam circuitus apertus) donec voltus trans eum attingit certum valorem, ubi sua resistentia decidit permitting currentem duci per apparatum. Quando conducit, MOV etiam claudicat voltum trans se ad constantem valorem.
Huiusmodi apparatus frequenter utitur in systemibus altis tensibus ut absorber surgorum et ut apparatus protectionis pro componentibus sensibilis voltu.
Duas topologias bi-directionales disjunctorum circuiti solidi status ostenduntur in Figura 2. Quando disjunctor clausus est, ambo dispositiva semiconductoria excitantur, permittentes currentem fluere in ambabus directionibus. Durante interruptionem currentis, ambo dispositiva desinunt, cogentes voltum trans dispositiva crescere donec MOV incipiat ducere et claudicare voltum trans dispositiva. Conducens MOV agit ad dissipandum conservatam energiam intra inductivitatem circuiti.
Cum IGCTs ostendantur in Figura 2 (a), GTOs etiam usi sunt in vetustioribus designis basatis in eadem topologia circuiti.

 
Figura 2   a) Simplicis disjunctoris circuiti solidi status bidirectionalis basati in IGCT, (b) Simplicis disjunctoris circuiti solidi status bidirectionalis basati in IGBT

Figura 3 ostendit numerum alternativarum designatorum quae hoc conceptum applicant ad systemata mediis tensibus. In his systematis, plures dispositiva series connectuntur ad augendum totalem voltus sustinentiam disjunctoris solidi status. Diodes etiam saepe series connectuntur cum principalibus commutatoribus rumpendi ad meliorandum reversum voltus systematis, propter limitatam reversam potentiam dispositivorum existentium sicut IGCT et GTO. Circuitus ostenditur in Figura 3 (c) includit RC snubbers paralleliter connectos qui requiruntur pro systematis GTO-based ad auxiliandum desinitioni dispositivorum, et etiam continet duas interessantes features quae possunt applicari ad alios disjunctores circuiti solidi status. Primo, includit resistorem paralleliter connectum qui utitur ad limitandum currentem defectus durante interruptionem currentis. Durante operationem normalem, hic resistor shorted out est per principales commutatores semiconductores et ideo non contribuit ad on-state perditiones disjunctoris. Secundo, commutator mechanicus series connectus est ad praebendum physicam isolationem.
Cum designata ostenta in hac sectione primarie sint designata pro systematis ac potentiis, debet fieri ut haec designata applicentur ad applicationes dc minimis modificationibus.

 
Figura 3: a) Disjunctor circuiti bidirectionalis medii tensibus basatus in IGCT, (b) Disjunctor circuiti bidirectionalis medii tensibus basatus in IGCT, (c) Disjunctor circuiti bidirectionalis basatus in GTO

Simplificatum diagramma bloccum disjunctoris circuiti solidi status ostenditur in Figura 4. Interruptor solidi status circuiti constat ex serie dispositivorum solidi status ad secure tractandum DC bus voltus. Celer controller inversus temporis coordinatus praebet signum gate drive pro commutatoribus in interruptore qui synchronous aperiunt et claudunt. Celer controller inversus temporis recipit mandata vel a manuale input, ab aliis disjunctoribus in rete, vel a celeribus sensoribus qui detectant locales currentes defectus. Controller inversus temporis praebet controllem inversum temporis pro overcurrent states, et celer instantaneous trip si overcurrent limit attingitur. Haec operationalia parametra possunt ajustari pro unoquoque disjunctore secundum eius locum in rete, praebendo ordinatum, sequenced responsionem ad conditiones defectus.

 
Figura 4: Simplificatum diagramma systematis typici MVDC disjunctoris circuiti solidi status

Interruptor solidi status praebet primarium functionem assembly complete disjunctoris circuiti celer protectionem defectus et isolationem. Assembly complete disjunctoris circuiti etiam debet praebere modum securum disconnectendi interruptorem ab rete potenti quando maintenance vel service requiritur.
Preliminaris layout pro 8 MW load-level interruptor ostenditur in photo 1. Hic interruptor
constat ex sex 4,500 V IGBTs (CM900HB-66H) series connectis. Interruptor 8 MW est
circa 23” latitudinis x 9” altitudinis  11” profunditatis et pondo est circa 60 lb. IGBTs montantur
super cold plates aluminium aqua-refrigerati, quae, in vicem, montantur super frame mechanicum electrically insulating. Aqua lines non-metallicae sufficienter resistive sunt ad limitandum currentem leakage down lines.
Hoc requirit parvum, closed-loop cooling system et long-lasting ion-exchange cartridge ad maintinendum
resistivitatem aquae refrigerantis.
Hoc requirit parvum, closed-loop cooling system et long-lasting ion-exchange cartridge ad maintinendum resistivitatem aquae refrigerantis.
In photo 1 ostenditur preliminaris layout mechanicus interruptoris 10 kV, 8 MW (800 A) IGBT. IGBTs montantur super cold plates aqua-refrigeratas. Non-metallic cooling lines inter adjacent cold plates designed sunt ad stand off full switch voltage quando switch apertus est.
Parallel arrays of these assemblies are used to meet the overall current requirements for the load.

 
Photo 1: Preliminaris layout mechanicus interruptoris 10 kV, 8 MW (800 A) IGBT. IGBTs montantur super cold plates aqua-refrigeratas

Compare the advantages and disadvantages of Solid-State Circuit breakers with other circuit breakers briefly:
While solid-state circuit breakers can achieve substantially faster interruption speed compared to conventional electro-mechanical-based circuit breakers, one major drawback of solid-state breakers is their high on-state losses. With contact resistance as small as a few micro-ohms, electro-mechanical contacts in classical circuit breakers introduce negligible on-state losses. In contrast, most solid-state devices introduce a voltage drop of at least two volts, therefore as a large current flows through the breaker, the on-state losses of a solid-state circuit
breaker can be significantly higher than those of a classical circuit breaker. The increased energy loss also leads to increased requirements for cooling. Traditionally large metallic heatsinks are used to passively cool power semiconductor devices, however, they can contribute to substantial portions of the systems’ overall size and weight. While the installation of active cooling systems such as forced air (fan) or liquid cooling might help to reduce the size and weight of the overall system, they introduce additional complexities such as increased acoustic signature, energy losses, and maintenance issues.
According to figure 5, the values are given in relation to the highest value per group.
For every criterion, small values are considered to be preferable. A small area, therefore, indicates an overall good performance of a switching concept.
Based on the findings, the solid-state circuit-breaker shows a good overall performance. Due to its fast switching capabilities, the turn-off time is small and only low current amplitudes occur. Also, the reliability and the complexity of the switching process can be considered to be good. However, the solid-state breaker suffers from high losses, compared to mechanical or hybrid switches.
An alternative concept with low losses, medium relative costs, and good reliability is the snubber mechanical breaker. Also, the conventional hybrid breaker shows an overall medium performance. It suffers from high peak currents due to the mechanical switch. The concepts taken from HVDC systems do not have a good performance within the voltage and power levels investigated. However, for higher voltages and powers, this might change. Finally, the concept of a pure mechanical-breaker is still interesting for low and low-medium voltage applications since it’s the only well-proven one.

Figura 5: Overview of all switching concepts for DC circuit breakers

Table 1 summarizes the characteristics of the four circuit breaker technologies:
It should be noted that the time of preparation of this table is 2012.

 
Tabula 1: Summary of circuit breakers technologies for low power DC applications