Faster Testing

With HIGHVOLT’s new pow­er sup­ply plat­form for test equip­ment, a pow­er elec­tron­ic sup­ply unit is now avail­able for the first time—marking anoth­er step for­ward into the future of pow­er sup­ply tech­nol­o­gy.

Text: Martin Buschendorf

New devel­op­ments and tech­no­log­i­cal progress change our lives. Long-dis­tance calls made from a phone booth or phones with a rotary dial are now just a chap­ter in the his­to­ry books. Nowa­days, almost every­one uses a smart­phone and couldn’t imag­ine life with­out the huge range of func­tions besides phone calls that these devices offer. Anoth­er change that is famil­iar to us all today is the move from the com­bus­tion engine to the elec­tric car.

The Rein­hausen Group has seen its own fair share of developments—drawing boards for design­ing on-load tap-chang­ers or test­ing tech­nol­o­gy are yet more exam­ples of things that have been con­signed to the past. In fact, tech­no­log­i­cal progress has tak­en hold across every indus­try, and con­ven­tion­al sys­tems are being replaced with smart ones. As a glob­al tech­nol­o­gy leader, HIGHVOLT is also opt­ing for intel­li­gent solu­tions for its prod­ucts. Volt­age con­trol involv­ing a mechan­i­cal­ly oper­at­ed reg­u­lat­ing transformer—a method that has been around for dec­ades—is grad­u­al­ly being replaced by an pow­er sup­ply plat­form known as the elec­tron­ic pow­er source (EPS).

What the electronic power source does

In order to explain just how big a step this is, this arti­cle intends to pro­vide a brief overview of what the EPS does, how it dif­fers from the cur­rent solu­tion, and what inno­va­tions and cus­tomer ben­e­fits it brings with it. To achieve a test volt­age of sev­er­al hun­dred thou­sand volts, the avail­able line volt­age is con­vert­ed to a much high­er lev­el via trans­form­ers. This works in a sim­i­lar way to a pri­ma­ry sub­sta­tion used by a domes­tic ener­gy sup­pli­er. To pre­vent the object that is the sub­ject of the test from being destroyed, the out­put volt­age needs to be reg­u­lat­ed.

And there’s a lit­tle trick that can be used to do this, which involves reg­u­la­tion tak­ing place straight away at the low-volt­age side. The effect of the trans­fer ratio can then be seen at the out­put. To put it in sim­pler terms, if you have connect­­ed a sys­tem with a max­i­mum volt­age of 500,000 volts to a 400-volt grid and then set 200 volts at the input, there will be 250,000 volts at the out­put. Sim­i­lar­ly, if 40 volts are set at the input, there will be 50,000 volts at the out­put, and so on.

 

Pre­vi­ous­ly, a reg­u­lat­ing trans­former was used to achieve this. This mech­a­nism con­veys a cur­rent col­lec­tor across the wind­ings with the aid of a mechan­i­cal dri­ve, adjust­ing the volt­age from 0 to 400 volts as a result. The size of the struc­ture used can vary sig­nif­i­cant­ly depend­ing on the con­nect­ed load and con­nec­tion volt­age. The sup­ply grid is loaded asym­met­ri­cal­ly on two of three phas­es.

It is at pre­cise­ly these points that the EPS comes in. At the grid con­nec­tion, there is an elec­tron­ic pow­er circuit—known as the active front-end—provided direct­ly by col­leagues at MR PQ. This is used to rec­ti­fy the AC volt­age from the grid and then feed it into a DC link capac­i­tor. From there, a spe­cial­ly devel­oped pow­er invert­er with IGBTs act­ing as semi­con­duc­tor switch­es pro­vides a vari­able, fine­ly adjustable out­put volt­age between 0 and 690 volts.

The grid load is dis­trib­uted even­ly across all three phas­es and the reg­u­la­tion pro­ce­dure becomes much more pre­cise and far faster—without the need for any mechan­i­cal mov­ing parts. To pre­vent the need to man­age lots of dif­fer­ent designs, the rec­ti­fi­er and the pow­er invert­er can be con­nect­ed in a mod­u­lar man­ner, and the sys­tem can be scaled sim­ply by chang­ing the num­ber of iden­ti­cal mod­ules incor­po­rat­ed into the sys­tem.

Low­er oper­at­ing costs, short­er test times, sim­ple expan­sion options, and quick and easy repairs — the new sys­tem deliv­ers a whole range of ben­e­fits

This pro­vides a whole host of ben­e­fits to cus­tomers. In addi­tion to the more pre­cise and faster volt­age reg­u­la­tion that has already been described, excess ener­gy in the res­o­nant cir­cuit can now be fed back from the correspond­ing test­ing sys­tems to the pow­er grid. Of par­tic­u­lar inter­est is the vari­able sys­tem fre­quen­cy, which can be set to be­tween 0 and 500 hertz.

This enables our cus­tomers to per­form tests for the entire glob­al mar­ket using 50 hertz and 60 hertz—regardless of their actu­al loca­tion and the asso­ci­at­ed line fre­quen­cy lim­its in dif­fer­ent coun­tries. Addi­tional fre­quen­cy vari­a­tions can also be used to expand the test range or to take spe­cial mea­sure­ments for the pur­pose of locat­ing faults—measurements that were not pos­si­ble pre­vi­ous­ly. In addi­tion, the sys­tem enables har­mon­ics to be active­ly com­pen­sat­ed or applied in spe­cif­ic ways.

Modular system

Essen­tial­ly, the cus­tomer receives a sys­tem that can be extend­ed as need­ed and will be well placed to meet what­ever future demands it faces. What’s more, should there ever be a prob­lem, the indi­vid­ual mod­ules can be repair­ed quick­ly, mean­ing that the sys­tem will only be out of action for a few hours.

The mod­u­lar design enables cus­tomers to ben­e­fit from the full range of func­tions that the sys­tem offers from the out­set and upgrade it eas­i­ly at any time. A whole host of prop­er­ties that are cur­rent­ly deliv­ered through add-on com­po­nents come already inte­grat­ed in the EPS, such as har­mon­ic com­pen­sa­tion, short-cir­cuit detec­tion, and emer­gency shut­down.

The sup­ply plat­form is being intro­duced in stages. Facil­i­ties with a sin­gle-phase out­put volt­age for AC sys­tems of type WP (trans­former-based) and type WRM (based on the res­o­nance prin­ci­ple) will be the first to be equip­ped with the EPS. This will be fol­lowed by the adap­ta­tion for mod­u­lar DC test equip­ment. The devel­op­ment of the three-phase EPS means that trans­former test sys­tems for low-volt­age and medi­um-volt­age trans­form­ers will soon be avail­able with the new EPS fea­ture too. The func­tions pro­vid­ed by the sys­tem are con­stant­ly being expand­ed.

Customer benefits

The biggest chal­lenge when it came to devel­op­ing the EPS was achiev­ing a low noise lev­el. Tests can only be done if what is known as the par­tial dis­charge back­ground noise lev­el is much low­er than the sig­nal being mea­sured. The experts at HIGHVOLT have suc­ceed­ed in reduc­ing this noise lev­el to < 1 pC (pic­o­coloumb), mean­ing that it is below the lev­el of con­ven­tion­al feed-ins.

Despite the exten­sive enhance­ments the EPS offers, it does not cost cus­tomers any more to pur­chase and even saves them mon­ey dur­ing oper­a­tion thanks to short­er test times, sim­ple expan­sion options, and quick and easy repairs. Not only that, but cus­tomers also ben­e­fit from a much wider range of func­tions that they can select based on their needs.


YOUR CONTACT


Do you have any ques­tions about the elec­tron­ic pow­er source?
Mar­tin Buschen­dorf is here to help:
M.Buschendorf@highvolt.com


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