This project will develop a coordinated real-time sub-transmission volt-var control tool (CReST-VCT) to optimize the use of reactive power control devices for stabilizing voltage fluctuations caused by intermittent photovoltaic (PV) outputs. In order to capture the full value of the volt-var optimization, the project team will couple this tool with an optimal future sub-transmission volt-var planning tool (OFuST-VPT) for short- and long-term planning analyses. Together, these real-time control and planning tools will remove a major roadblock in the increased penetrations of utility scale and residential PV.
CReST-VCT will be built based on algorithms that can coordinate the control logic of existing grid reactive power compensation devices from the sub-transmission network level down to the distribution networks, along with required var support from distributed PVs. This tool will also use advanced quasi-steady-state models and control algorithms for PV inverters, load-side management solutions, and a model reduction tool to reduce the complexity of distribution circuit models for sub-transmission analysis and optimization. In addition, OFuST-VPT will incorporate algorithms to optimize the type, size, and location of new compensation devices that provide the best coordination with existing devices and meet future PV integration needs. CReST-VCT will be demonstrated and validated on microgrid test systems at North Carolina State University with hardware-in-the loop simulations. Field demonstration will be performed on the Duke Energy system feeder test bed and selected sub-transmission networks.
The successful development of the CReST-VCT and OFuST-VPT tools will improve grid voltage stability, reduce system losses, and secure grid operations. These, in turn, will enable the SunShot’s Grid Performance and Reliability target metric of 100% PV penetration levels at peak load.