Largest US grid operator PJM begins annual review of proposed large load adjustments ↧ ↧ Largest US grid operator PJM begins annual review of proposed large... PJM Interconnection, the largest US grid operator, said Tuesday it has begun its annual ​review of proposed Large-Load adjustments to ‌its 2027 Long-Term Load Forecast, using new guidelines to better gauge how likely projects are to materialize.