4 research outputs found
A Supervisory Volt/VAR Control Scheme for Coordinating Voltage Regulators with Smart Inverters on a Distribution System
This paper focuses on the effective use of smart inverters for Volt/Var
control (VVC) on a distribution system. New smart inverters offer Var support
capability but for their effective use they need to be coordinated with
existing Volt/Var schemes. A new VVC scheme is proposed to facilitate such
coordination. The proposed scheme decomposes the problem into two levels. The
first level uses Load Tap Changer (LTC) and Voltage Regulators (VRs) and
coordinates their control with smart inverters to adjust the voltage level on
the circuit to keep the voltages along the circuit within the desired range.
The second level determines Var support needed from smart inverters to minimize
the overall power loss in the circuit. The results of the supervisory control
are sent to the devices which have their local controllers. To avoid frequent
dispatch, smart inverters are supervised by shifting their Volt/Var
characteristics as needed. This allows for the smart inverters to operate close
to their optimal control while meeting the limited communication requirements
on a distribution system. A case study using the IEEE 34 bus system shows the
effectiveness of this supervisory control scheme compared to traditional
volt/var schemes.Comment: Submitted to IEEE Transactions on Power System
Multi-Feeder Restoration using Multi-Microgrid Formation and Management
This papers highlights the benefit of coordinating resources on mulitple
active distribution feeders during severe long duration outages through
multi-microgrid formation. A graph-theory based multi-microgrid formation
algorithm is developed which is agnostic of the underlying energy management
scheme of the microgrids and solved in a rolling horizon fashion. The algorithm
is then enhanced to handle multiple feeders where formation of long laterals
needs to be avoided due to potential voltage control issues in distribution
systems. The algorithm is evaluated on a synthetic two feeder system derived
from interconnecting two IEEE 123 node system. The results indicate increased
service to loads in the system and better utilization of renewable resources.Comment: Submitted to IEEE PESGM 202
A Load Switching Group based Feeder-level Microgrid Energy Management Algorithm for Service Restoration in Power Distribution System
This paper presents a load switching group based energy management system
(LSG-EMS) for operating microgrids on a distribution feeder powered by one or
multiple grid-forming distributed energy resources. Loads on a distribution
feeder are divided into load switching groups that can be remotely switched on
and off. The LSG-EMS algorithm, formulated as a mixed-integer linear
programming (MILP) problem, has an objective function of maximizing the served
loads while minimizing the total number of switching actions. A new set of
topology constraints are developed for allowing multiple microgrids to be
formed on the feeder and selecting the optimal supply path. Customer comfort is
accounted for by maximizing the supply duration in the customer preferred
service period and enforcing a minimum service duration. The proposed method is
demonstrated on a modified IEEE 33-bus system using actual customer data.
Simulation results show that the LSG-EMS successfully coordinates multiple
grid-forming sources by selecting an optimal supply topology that maximizes the
supply period of both the critical and noncritical loads while minimizing
customer service interruptions in the service restoration process.Comment: 5 pages, 7 figures, submitted to 2021 IEEE PES General Meetin
A Novel Feeder-level Microgrid Unit Commitment Algorithm Considering Cold-load Pickup, Phase Balancing, and Reconfiguration
This paper presents a novel 2-stage microgrid unit commitment (Microgrid-UC)
algorithm considering cold-load pickup (CLPU) effects, three-phase load
balancing requirements, and feasible reconfiguration options. Microgrid-UC
schedules the operation of switches, generators, battery energy storage
systems, and demand response resources to supply 3-phase unbalanced loads in an
islanded microgrid for multiple days. A performance-based CLPU model is
developed to estimate additional energy needs of CLPU so that CLPU can be
formulated into the traditional 2-stage UC scheduling process. A per-phase
demand response budget term is added to the 1st stage UC objective function to
meet 3-phase load unbalance limits. To reduce computational complexity in the
1st stage UC, we replace the spanning tree method with a feasible
reconfiguration topology list method. The proposed algorithm is developed on a
modified IEEE 123-bus system and tested on the real-time simulation testbed
using actual load and PV data. Simulation results show that Microgrid-UC
successfully accounts for CLPU, phase imbalance, and feeder reconfiguration
requirements.Comment: 10 pages, submitted to IEEE Transactions on Smart Gri