C. Functional Tests for Inverters and Controllers
Inverters and controllers designed to provide reverse or underpower functions shall be tested to certify the intended operation of this function. Two methods are provided:
Method 1: If the controller uses external current/voltage measurement to determine the reverse or underpower condition, then the controller shall be functionally tested by applying appropriate secondary currents and potentials as described above in 1. A) Reverse Power Relay Test.
Method 2: If external secondary current or potential signals are not used, then unit-specific tests must be conducted to verify that power cannot be exported across the point of common coupling for a period exceeding two seconds. These tests may be factory tests, if the measurement and control points are part of a single unit, or may be provided for in the field.
2. In-rush current test procedure 1
This test will determine the maximum in-rush current drawn by the unit. Two methods are provided:
Locked-rotor method: Use the test procedure defined in NEMA MG 1 (manufacturer's data is acceptable if available).
Start-up method: Install and set up the generating facility equipment as specified by the manufacturer. Using a calibrated oscilloscope or data-acquisition equipment with appropriate speed and accuracy, measure the current draw at the point of common coupling as the generating facility starts up and comes into parallel with EDTI's distribution system. Start-up shall follow the normal manufacturer-specified procedure. Sufficient time and current resolution and accuracy shall be used to capture the maximum current draw within 5%. In-rush current is defined as the maximum current draw from EDTI during the start-up process, using a 10-cycle moving average. During the test, the utility source, real or simulated, must be capable of maintaining voltage within +/–5% of rated at the connection to the unit under test. Repeat this test five times. Report the highest 10-cycle current as the in-rush current. A graphical representation of the time-current characteristic along with the certified in-rush current must be included in the test report and made available to EDTI.
Pacific Gas and Electric Company, Rule 21 – Generating Facility Interconnections, January 5, 2001.
3. Synchronization test procedure
This test verifies that the unit synchronizes within the specified voltage/frequency/phase angle requirements.
The test will start with only one of the three parameters:
- voltage difference between the generating facility and EDTI's distribution system,
- frequency difference or
- phase angle outside of the synchronization specification.
Initiate the synchronization routine and verify that the generating facility is brought within specification prior to synchronization. Repeat the test five times for each of the above three parameters. For manual synchronization with synch-check relay or manual control with auto-synchronization relay, the test must verify that paralleling does not occur until the parameters are brought within specifications.