Download minute word #1 ( docx , 156 kB )

A2 -50
21, rue d’Artois, F-75008 PARIS
Meeting # 1
11 Sept 2013
MINUTE OF MEETING # 1 ZURICH 09/11 2013
1. Introduction
The working group met on Wednesday September the 11th in ETH at Zurich.
The subject was heavily discussed and the following salient points were raised:
 Increase of bidirectional power flow very difficult to control
 Reactive power transmission do exists
 Problem of voltage regulation and insufficient number of tapping were experienced, with risk of over fluxing
and core saturation
 IEC allows insufficient core overfluxing under load for step up operation
 Example of pump storage power plant where transformers are subject to multiple load inversion. Some new
transformers are equipped with fiber optics to raise evidence of differences in temperature rise between site
and test field
 Effect of capacitive loading on both core and shell type shall be envisaged
 Japanese practice with tertiary capacitor for var supply
 Experience of distribution networks where low voltage sides capacitor bank are fitted
 Three winding operation with generation on one secondary and load on an other
 Influence of PV and need for tap changer in distribution type transformers
 Power electronic harmonics does not seems to be a problem within usual grid code limits.
The need for more participants was expressed at the main committee meeting on Thursday and at least a member
from Protection and control was required via a liaison.
2. Next meeting
No fixed date was retained at the meeting due to the attendance. Nevertheless a meeting will be held in Paris during
the session, and if possible at least one web conference or meeting shall be made prior to it beginning of 2014.
Document1
p 1/3
3. Attendance
4. Work
Despite the limited attendance a forecast table of content was established and lecture of the inputs by Bob Singh was
made.
4.1 Table proposal







Document1
Introduction
Report of existing problems
o Example
o Different possible concerns and effects in transformers ( such as harmonics and winding hot spot,
overfluxing and core hot spot) linked to reverse power flow
o Effect of active and reactive power flow
Transformer construction and a few theory
o How is flux density fixed
• Core type
• Shell type
o Stray flux
• Where does the stray flux go
• Effect of capacitive load
o Voltage drop (and raise)
Forecasted load flow evolution on “smarter grid”
o Some general consideration on load flow and smart grid
Step up step down operation influence on design
o Typical configuration for distribution network
o double LVs transformers
Effect of flux density and stray flux
o Temperature rise (core, hot spot)
o Noise (due to “overfluxing” due to voltage and current or due to load)
o Other performances
Tap changer design
p 2/3








o Tap changer for both way power flow (asymmetrical pennant cycle ?)
o Does it affects the design of the tap changer ?
o Differences with conventional tap changer
o What about DETC ?
Step up step down operation influence on design
o Typical configuration for distribution network
o double LVs transformers
Effect of flux density and stray flux
o Temperature rise (core, hot spot)
o Noise (due to “overfluxing” due to voltage and current or due to load)
o Other performances
Tap changer design
o Tap changer for both way power flow (asymmetrical pennant cycle ?)
o Does it affects the design of the tap changer ?
o Differences with conventional tap changer
o What about DETC ?
Voltage regulation
o Tap changer control ( P&C inputs requested)
o System view of the transformer control policy U, I both , where LV ? HV? For distribution and
transmission
o Voltage drop ( effect of high impedance end power factor)
o Reactive power control
o Reactive power circulation
o Tapping range
o Regulated voltage (LV with HV taps ?)
o Tapping winding position (HV/LV)
o DETC ?
Effect of harmonics of current and voltage
o On no load losses
o On load losses
Mitigation and usage restrictions
o Typical example or real cases
Conclusion : advices
o Risks on existing fleet
o Special requirement for new specification
o Recommendation to standardization update ( 76-1 ?)
Bibliography
4.2 Work assignment
Some work assignment was proposed as follows
 Introduction:
JC RIBOUD
 Typical Configurations :
M ZOUITI
 Effects of harmonics : G GURSKY
 Example of Mitigation : B SINGH (if agreed)
Document1
p 3/3