Analysis and control of PV inverters operating in VAR mode at night

Abstract

Although the number of PV installations is rapidly growing, the effective utilization of PV inverters remains low. On average, most of today's grid-tie PV inverters operate an average of 6-8 hours per day. In order to increase the utilization of grid-tie PV inverters, they can be operated in reactive power compensation mode when PV power is unavailable. While injecting reactive power into the grid can be easily realized by applying the appropriate phase shift between current reference and grid voltage, the task gets more complex when PV power is not available since the inverter needs to draw power from the grid, regulate the DC bus, and inject the desired level of reactive power. This paper will provide a detailed analysis of PV inverters' operation in VAR compensation mode when active power is not available. A new control scheme is proposed that enables inverter to absorb little active power from grid, regulate its DC bus voltage within limits, and inject the desired level of reactive power. Simulation and experimental results are provided to validate the analysis. I.

Variable speed drives for power factor correction in the water sector

“…operate the power electronics in the front end of the drive) and 2) regulate the voltage of the drive's DC bus [49]. Typically, active power to overcome inversion losses is supplied by a portion of the electricity already demanded from the grid or generated by the renewable resource [49].…”

“…Typically, active power to overcome inversion losses is supplied by a portion of the electricity already demanded from the grid or generated by the renewable resource [49]. In this case, that power must be drawn from the grid.…”

“…In addition, it must be in excess of inversion losses to ensure adequate charging of the DC bus [49]. One study recommends that the "active power command," or the portion of any control logic that would allow for DC charging, be set to −K × P losses where K > 1 [49].…”

Real‐time reactive power distribution in microgrids by dynamic programing

“…A first step is to divide the microgrid into smaller clusters. Recent microgrid studies ( [1], [22], [23], [24] and a review in [4]), indicate that microgrids are not arbitrarily meshed topologies, but in fact designed with a typical structure: peripheral clusters that are assembled around a central PCC. Examine, for instance, the study system in [22], where this clustered structure is explicitly shown.…”

An evaluation of options to mitigate voltage rise due to increasing PV penetration in distribution networks

“…±0.9 PF. The final prosumer option to be evaluated is solar inverters with a Q(V) characteristic, where the ±Q limits are independent of P (statcom functionality), as some solar inverters now have this mode [7]. In this analysis, it is assumed that the inverters operating in the Q(V) modes do not have communications with a network control centre to enable Q(V) setting changes.…”