Benefits of HTS Power Cables – Fitting More Power into Existing Space

Increase reliability and security of power grid:  “Smart,” controllable HTS cables can make the power networks in which they are installed self-protecting – able to adjust rapidly and automatically to disruptions in power network equipment caused by weather, willful destruction or other factors.

Increase power transmission capabilities in existing rights-of-way:  HTS cables have a very small installed physical footprint, making them easier to site even in dense, older urban areas.  HTS cables can carry more power than conventional cables.  The high ampacity of HTS cables allows 3 to 5-times the power for AC systems and up to 10 times the power for DC systems to be delivered at equivalent voltage, or equivalent power to be delivered at reduced voltage. For instance, a HTS cable operating at 115 kV can have the same MVA rating than a 345 kV cable.  This combination of high power capacity and compact size makes HTS cables a superior solution in situations where conventional cables and/or overhead lines would be difficult or impossible to site.

Reduce or eliminate environmental impacts in new and existing rights-of-way:  Underground solutions with HTS cables are faster to gain approval than time-consuming overhead installations requiring extensive permitting and environmental impact studies and reviews.  In addition, an installation with HTS cable can provide the same transfer power capacity as an overhead installation, unlike conventional underground copper cables, which requires multiple circuits and significantly more land use.   HTS cables can be installed in a narrow trench using low impact methods, eliminating the traffic congestion and run-off concerns associated with conventional cable installations.  HTS cables contain no oil, eliminating containment issues associated with conventional oil-filled cables.  The shielded construction of cold dielectric cables also eliminates external electromagnetic fields common to overhead and underground transmission technologies.

Minimize permitting by reusing rights-of-way:  HTS cables eliminate the need to increase system voltages to increase system capacity, allowing capacity increases in existing permitted rights-of-way.  Additionally, cold dielectric cables do not generate external electromagnetic fields (EMF), thus eliminating a major source of concern of impacted abutters.  HTS cables significantly reduce the disruptions caused by the cable construction and installation activities.

Greater control of AC power flow within the grid:  HTS power cables have significantly lower impedance than conventional cables.  This characteristic means that they can be strategically placed in the grid to draw flow away from overtaxed conventional cables or overhead lines, thereby relieving network congestion.   Low impedance cables can also provide solutions to grid congestion problems and enable new grid configurations.  HTS cable offers the ability to control power flows with conventional, proven technology (e.g., series reactors, phase angle regulators).  This combination yields market and reliability benefits typically associated with other “controllable” forms of transmission, e.g., FACTS or DC transmission.

Shorten project implementation time - Complete underground solutions faster:  Because the permitting cycle can be completed faster, HTS cable systems are expected to offer a strategy to ease grid congestion more quickly and to enable significantly faster project completion when compared to projects that utilize conventional cable systems.

Lower installation costs than traditional copper-wire cables:  Installation of HTS cable is significantly easier, thus less expensive, than the installation of conventional cable.  HTS cable can be installed in a single, narrow trench using commonly available installation equipment, with no conductor spacing requirements because they are thermally independent of the environment.  Conventional cables installations require wide conductor spacing (i.e. wide trench) and expensive thermal backfills to control heating of the cable and the ground. In addition, because HTS cables can operate at lower voltages, more expensive high voltage equipment and transformation losses can be avoided. With HTS cable, utilities may solve power flow problems with shorter circuit lengths, e.g., connecting to the more pervasive 115/138/161 kV system rather than tying back to the more distant EHV backbone transmission system.