table 1. Required disturbance ride-through capability for DER in the proposed 1547 revision. Performance Requirement Abnormal Operating Performance Category Voltage ridethrough (proposed) Frequency ride-through (proposed) Foundation Justification I German grid code for mediumvoltage-connected DER with rotating machines * Essential bulk system needs * Attainable by all state-of-the-art DER technologies II (Figure 10) NERC PRC-024-2* * All bulk system needs * Coordinated with existing reliability standards * Considering fault-induced delayed voltage recovery III California Rule 21 and Hawaii * All bulk system needs * Considering fault-induced delayed voltage recovery * Distribution system operation All categories (Figure 11) California Rule 21 and Hawaii** * All bulk system needs * Includes frequency response * L ow inertia grids capability with a default deadband of 36 mHz *Without stability exception but with an extended low-voltage ride-through duration for 65-88% V nom . **Exceeds PRC-024-2. Category II 1.30 May Ride-Through 0.16 s or May Trip 1.20 2 1s Permissive Operation Capability 1.10 1.10 p.u. Continuous Operation Capability 1.00 (Subject to Requirements of Clause 5) 0.88 p.u. 0.88 p.u. May Ride-Through or May Trip 0.90 Mandatory Operation Capability Voltage (p.u.) 0.80 0.70 Shall Trip 1.20 p.u. May 13 s 1 Ride-Through 1 0.65 p.u. 0.60 0.50 0.40 Permissive Operation Capability 0.45 p.u. 0.16 s 2 0.32 s 2s 21 s Legend Range of Adjustability Default Value 0.50 p.u. Shall Trip Zones 2s 0.16 s May Ride-Through or May Trip Zones Shall Ride-Through Zones and Operating Regions Describing Performance 0.30 0.20 May Ride-Through or May Trip 0.10 0.00 0.01 0.00 p.u. 0.1 0.00 p.u. 1 10 Shall Trip 100 1,000 Time (s) figure 10. The voltage ride-through requirements for DER in category II. (Source: Sponsor-Ballot Draft Standard for Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power Systems, IEEE P1547/D6.7.2, May 2017.) 58 ieee power & energy magazine november/december 2017