Voltage peak shaping for increased PV hosting capacity using a multi-frequency DVR

This work shows how a multi-frequency Dynamic Voltage Restorer (DVR) equipped with voltage peak-shaping capability can raise the amount of photovoltaic (PV) power that low-voltage (LV) distribution feeders are able to accept. Peak shaping is realized with Proportional-Resonant (PR) regulation, which lowers the crest factor of the waveform so that, for a fixed instantaneous peak-voltage limit, the fundamental component—and hence the injectable current—can be increased within the shaped feeder section before the same instantaneous peak-voltage limit is reached. Because the binding constraint is the instantaneous peak rather than the fundamental, flattening the crest releases headroom under that limit, which the PV inverters use to feed additional current into the grid, increasing the power-injection headroom of the feeder section. The multi-frequency injection and its multi-PR control were validated experimentally on laboratory hardware, and the resulting gain in hosting capacity was evaluated for two feeder arrangements, a 3-wire and a 4-wire one. In the 3-wire case, holding the crest at the 360 V ceiling raises the injectable active power from a baseline of 64.4 kW with the DVR disabled to 91.84 kW with the DVR enabled, at the same peak limit. The 4-wire arrangement performs even better: at the identical 360 V peak limit the injectable power reaches 120 kW. In both cases the DVR reshaped the voltage waveform while holding distortion low; the fundamental is unchanged by the reshaping itself, and it is the resulting peak-voltage headroom that permits a larger fundamental and hence a larger injected current. Overall, the multi-frequency DVR offers a practical, retrofit-based route to greater PV power-injection headroom that avoids reconductoring the feeder or altering its connections on the studied feeder section and represents an attractive alternative to conventional feeder reinforcement when rising distributed generation pushes voltages toward their limits.