Experimentally-calculated analysis of seismic resistance of GIS

The company "AtomSeismicProject" has done experimentally-calculated analysis of seismic resistance of Gas Insulated Substation on nominal voltage 330 kV (breef – GIS), developed and produced in "Electroapparat", JSC BI, Saint-Petersburg.

The aim of analyses was to determine seismic resistance of the item on seismic loads DLE (ductility level event) in different elevating systems and seismic magnitude on a scale MSK-64, seismic resistance estimation of equipment specified life configuration and its components gives an opportunity of spreading analyses results on other possible construction configurations.

Item (figure 1) was a complicated for testing and modeling construction consisting of standard elements and units (figures 2, 3, 4) connected by means of flanges, standing on supports produced from rolling sections (figure 5) (channel bars, double tees, angles). Fastener elements of gas insulated substation to supports is provided by nipping forks and free bearing. Besides, components of the substation are air tight and have internal pressure up to 0,9 MPa being made by insulating gas.

сейсмостойкость расчетная модель КРУЭ
Figure 1 – Calculated model GIS
Полюс выключателя
Figure 2 – Pole of a switching device
Звено КРУЭ
1 – tie bolt М30; 2 – high-speed earthing switch; 3 – current transformer; 4 – disconnector combined with earthing switch; 5 – joggle section; 6 – voltage transformer.
Figure 3 – GIS element
Звено КРУЭ 2
1 – connection bars; 2 – supporting formwork system ; 3 – disconnector combined with earthing switch; 4 – current transformer.
Figure 4 – GIS element
Опоры изделия 1 Опоры изделия 2
Опоры изделия 3 Опоры изделия 4
Figure 5 – item support

Experimental part consisted of determination of resonance frequency of item elements in the range of possible DLE influence up to 35 hz. Tests were done by the "free vibration measurement " for determination of natural frequencies and decrements item fade-out according to state standard 30630.1.1-99. Method of free-vibration excitation – applied shock by dynamometric hammer. Revealed dynamical behavior of the construction was used in the strength unit estimation for matching the model to the real item. Calculated mode shapes, figure 6.

Первая форма колебаний Вторая форма колебаний
а) first mode shape (9,5 Hz)
б) Second mode shape (11 Hz)
Figure 6 – Mode shapes
For seismic resistance verification there was done strength estimation of:

Split flange bolt of complete units;
Anchor bolts of supports;
Screw thread of attachment clips to support constructions;
Support constructions.
Experimentally-calculated seismic resistance estimation of the item showed that strength and working-capacity of the item stays in seismic exposure of:

Up to 9 points and ground elevation up to до 9 баллов +10 m;
Up to 8 points on a scale MSK-64 and ground elevation up to +35,0 м;
Up to 7 points on a scale MSK-64 and ground elevation up to +70,0 m,
and also sinusoidal vibration of frequency band from 0,5 to 35 hz with accelerating to 5 m/s2 (0,5g). Estimation of relocation bias from vibrational impact (figure 7) enables to give to the item mechanical fulfillment class M1 state standard 17516.1-90. 
Распределение модуля перемещений (мм) в элементах КРУЭ от вибрационного воздействия
Figure 7 – Displacement pattern module (мм) in GIS elements from vibrational impact