Event-Based Frequency Analysis in an African Transmission System Using Phasor Measurement Data

The West Africa Power Pool Integrated Transmission System (WAPPITS) intends to develop variable renewable energy (VRE) projectsto increase electricity access. However, concerns exist that increases in VRE - predominantly inverter-based generation - will likely exacerbate existing frequency problems in WAPPITS. Additionally, existing frequency control challenges have resulted in the operation of the WAPPITS as three (3) separate synchronous blocks, increasing the concern that WAPPITS can be operated reliably with increased VRE penetration. This paper uses selected frequency response metrics to analyze WAPPITS’ frequency response performance during recent system events. In this study, we used a recently-deployed wide area monitoring, primarily data from phasor measurement units. Results showed that primary control reserves in the WAPPITS’ synchronous areas were either non-existent or inadequate. Under-frequency load shedding was frequently used to maintain system frequency within acceptable limits. Insufficient, primary frequency control and lack of an automatic generation control system complicates frequency response throughout the system.