South Africa (NRS 097 / RPP) — ride-through requirements

The LVRT, HVRT, FRT envelopes a grid-scale battery must meet under South Africa (NRS 097 / RPP), digitized breakpoint by breakpoint and checked against the clause it came from.

By Sergey Syrvachev — Director of Product Engineering at HyperStrong

Applies to: both connections — RPP categories A3/B/C on transmission or distribution.

Part of: the grid-code ride-through chart — compare this against 65 other standards in 44 countries.

What this is, and is not. A reading aid compiled from the clause cited below — not a compliance document. The primary text governs. Every value here was read from a current primary source.

Breakpoints

Times are seconds from the start of the disturbance. Voltage is per-unit of nominal; frequency in hertz. An LVRT curve is a lower boundary (stay connected while voltage is on or above it), an HVRT curve an upper boundary, and FRT gives the band between its High and Low boundaries. These are the boundaries, not the behaviour: what holding one demands of the converter — reactive current injection, thermal stress, protection timing — is stepped through in the LVRT / HVRT ride-through visual.

EventDutyBreakpointsStatus
low-voltage ride-through (LVRT)ride-through0.001s → 0 pu; 0.15s → 0 pu; ↗ 2s → 0.85 pu; 20s → 0.85 pu; 20.001s → 0.9 pu; 60s → 0.9 puverified
high-voltage ride-through (HVRT)ride-through0.001s → 1.2 pu; 2s → 1.2 pu; 2.001s → 1.1 puverified
frequency ride-through (FRT)ride-throughHigh: 0.2s → 52 Hz; 4s → 52 Hz; 4.001s → 51.5 Hz; 60s → 51.5 Hz; 60.001s → 51 Hz | Low: 0.2s → 47 Hz; 6s → 47 Hz; 6.001s → 47.5 Hz; 10s → 47.5 Hz; 10.001s → 48 Hz; 60s → 48 Hz; 60.001s → 49 Hzverified

Where these values come from

  • LVRTGrid Connection Code for Renewable Power Plants (RPPs) connected to the Electricity Transmission or Distribution System in South Africa, Version 3.1, January 2022 - clause 5.2.1(b)(3) 'withstand voltage drops to zero ... for a minimum period of 0.150 seconds' and Figure 4 'Voltage Ride through Capability for the RPPs of Category A3, B and C utilising non-synchronous machines' (time axis breakpoints 0.0 / 0.15 / 2.0 / 4.0 / 20.0 s; 85% level marked). The code defines a linear recovery ramp; the vertices are read from the clause and the chart draws the segment between them.
  • HVRTGrid Connection Code for RPPs in South Africa, Version 3.1, January 2022, clause 5.2.1(b)(4) and Figure 4 Area D (p.16); Umax from Table 1 (p.12).
  • FRTSA RPP Grid Code v3.1 (Jan 2022), clause 5.1(4) (RPP shall be capable of operating for the minimum operating range illustrated in Figures 1 and 2), 5.1(5) 'When the frequency on the NIPS is higher than 51.5 Hz for longer than 4 seconds, the RPP shall be disconnected from the grid' and 5.1(6) 'When the frequency on the NIPS is less than 47.0 Hz for longer than 200ms, the RPP may be disconnected'; Figure 2 'Minimum frequency operating range of a RPP (during a system frequency disturbance)' (p.13) — upper boundary steps at 4 s (52 -> 51.5) and 60 s (51.5 -> 51.0); lower boundary steps at 200 ms (-> 47), 6 s (47 -> 47.5), 10 s (47.5 -> 48) and 60 s (48 -> 49); continuous range 49.0-51.0 Hz.

Last checked against the source document on .

How South Africa compares

Each event this code defines, put side by side with every other code that defines it:

Other grid codes in Africa