- SNom or Smax:
Maximum apparent power for which the plant with its components is designed.
- level of simultaneous provision:
Due to the converter topology, typically the maximum active power and the maximum reactive power cannot be delivered simultaneously, the power capacity is dependent on each other, the P-Q diagram of the system is circular or elliptical. However, for the stabilising effect of the E-STATCOM plants, it is necessary that active and reactive power are provided simultaneously. Therefore, it must be defined up to which limit this must be possible as minimum requirement.
- Pg in MW:
Active power that must be provided simultaneously with reactive power Qg. - Qg in Mvar:
Reactive power that must be provided at the same time as active power Pg.
- Storage in MWs@P2:
The storage size is defined uniformly. Since in some topologies the usable energy content of the short-term energy storage system depends on the discharging or charging capacity due to the internal resistance of the short-term energy storage system, the storage size is defined with a charging/discharging capacity and is understood as energy that can be made available to the AC grid.
- RoCoF2:
Rate of change of frequency (RoCoF) for the maximum instantaneous reserve call of the E-STATCOM system.
- P1:
Instantaneous reserve call for a frequency change of 1 Hz/s according to the design limit of the implemented system protection plan of the Continental European synchronous zone.
- P2:
Instantaneous reserve call-off for a frequency change of 2 Hz/s, for locally higher frequency changes above the design limit. Maximum possible active power.
The energy content of the storage and the maximum active power contribution P2, result in the maximum period of supply of active power at 375 MWs/150 MW = 2.5 s. With a resting state of charge of 50% at 50 Hz, this results in a charge/discharge duration at 2 Hz/s of 1.25 s until 47.5 Hz or 52.5 Hz is reached.
- Qn in Mvar:
Nominal value of the reactive power. The maximum permanently dissipatable reactive power Qmax is set to the same value.
- TA,P in s:
The planned configuration for the acceleration time constant by which the inertial response is defined. The acceleration time constant relates to the inertia time constant H as TA,P = 2 x H
- Inertia contribution in GWs:
Inertia contribution resulting from the acceleration time constant and the reference power. P1 is defined as reference power. The inertia contribution results to Inertia contribution = 1/2 * TAN * P1. This inertia contribution is the contribution of each E-STATCOM plant to the total inertia contribution that according to [6] shall be provided by the German transmission system.
The power is to be provided over the respective defined voltage range for quasi-stationary operation.