IEEE Power & Energy Magazine - March/April 2020 - 58

calculation methods with the new ones used in the prototype
EMS, which are an order of magnitude faster.

UHV ac Technical Standards
Building and operating a UHV ac transmission system is pioneering work. So far, only a few countries have established
UHV systems in operation. Since there are very limited UHV
transmission-line standards to guide system development, the
State Grid has encouraged the development of national and
international UHV ac guidelines. The current series includes
363 corporate, 145 industrial, 66 national, and 19 international standards. They were established from experience with
UHV ac transmission-line projects.
CIGRE established the following working groups (WGs)
to advance UHV:
✔✔ WG A3.22: Technical Requirements for Substation
Equipment Exceeding 800 kV
✔✔ WG B3.22: Technical Requirements for Substations
Exceeding 800 kV
✔✔ WG C4.306: Insulation Coordination of UHV ac
-Systems
✔ ✔ WG A3.28: Switching Phenomena and Testing
Requirements for UHV and Extra-HV Equipment
✔✔ WG B3.29: Field Test Technology on UHV Substation
Construction and Operation.
In 2008, the IEC and CIGRE recommended 1,000 kV
as the standard rated voltage, and the IEC approved it, on
22 May 2009, as the highest voltage for UHV ac equipment.
Since 2009, four IEC UHV ac standards have been approved:
1) a specification for 1,000-kV series-compensation equipment for transmission lines, 2) a specification for a 1,000-kV
controllable shunt reactor, 3) a guide related to acceptance
testing of 1,000-kV equipment, and 4) a recently approved
standard that applies to on-site acceptance tests of electrical
equipment where the highest ac transmission-system voltages
exceed 800 kV-(IEC TS 63042-301:2018, UHV ac Transmission Systems-Part 301: On-Site Acceptance Tests).

Three IEEE standards relate to UHV ac technologies.
1) IEEE Standard 1862-2014, IEEE Recommended Practice for Overvoltage and Insulation Coordination of
Transmission Systems at 1,000 kV ac and Above. This
standard covers the selection of UHV ac transmission-line and substation insulation-level methods. It
establishes reliability standards for operating during overvoltage and lightning overvoltage and recommends a calculation method for insulation coordination between transmission lines and substations. The
standard also recommends the overvoltage-control
measures for UHV ac systems of 1,000 kV and above.
2) IEEE Standard 1860-2014, IEEE Guide for Voltage Regulation and Reactive Power Compensation
at 1,000 kV ac and Above. This standard provides
voltage control and reactive compensation. It establishes standards and requirements for voltage
control and reactive-power compensation to ensure
system and equipment safety. It is applicable to the
planning, design, operation, and research of power
facilities with voltage levels of 1,000 kV and higher.
3) IEEE Standard 1861-2014, IEEE Guide for On-Site
Acceptance Tests of Electrical Equipment and System
Commissioning of 1,000 kV ac and Above. This standard provides guidance for on-site power-equipment
acceptance testing. It presents standards and requirements for test items, conditions, methods, and test
results. This standard describes specifications and
requirements for acceptance-test field procedures and
commissioning UHV ac-power equipment.

Best Practices and Recommendations

UHV ac transmission technology is groundbreaking. Besides
the common issues that challenge ac networks at low voltage levels, 1,000-kV UHV ac transmission projects face difficulties related to external insulation characteristics at high
altitudes, in heavy pollution, and during heavy icing. Their
designs must account for overvoltage
and insulation coordination, the EM
table 2. The comparison of the state-estimation execution time (ms).
environment, the ability to perform
Matrix
RHS
F/B
live maintenance, and so forth.
Method
Forma-tion
Factoriza-tion
Calculation
Substitution
For countries that want to incorpoTradi-tional
462.5
338.7
494.8
24.5
rate UHV transmission into their grids,
it is highly recommended to start with
New
15.7
13.4
48.4
2.5
a pilot project. Knowledge and expeRHS: right-hand side vector; F/B: forward/backward.
rience are important to achieve UHV
ac transmission success. Pilot projects
assess the performance and characteristable 3. The comparison of the power-flow
execution time (ms).
tics of the UHV ac transmission lines,
substations, equipment, and system, that
Branchis, shunt reactors, surge arresters, circuit
Matrix
RHS
F/B
Power
Method
Forma-tion Factoriza-tion Calcu-lation Substi-tution Calcu-lation
breakers, GIS, voltage transformers,
current transformers, and insulators.
Tradi-tional 6.3
80.6
87.7
25.1
3.7
They also offer opportunities to gain
New
5.3
14.7
5.4
0.7
1.6
experience in research, manufacturing,

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IEEE Power & Energy Magazine - March/April 2020

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