PHEVs Charging Stations, Communications, and
Control Simulation in Real Time
Luis Herrera, Robert Murawski, Feng Guo, Ernesto Inoa, Eylem Ekici, and Jin Wang
Department of Electrical and Computer Engineering
The Ohio State University
205 Dreese Labs; 2015 Neil Avenue
Columbus, Ohio, 43210
E-mail: wang@ece.osu.edu
Abstract- This paper introduces a platform for real time
simulation and its contribution towards smart grid related
research, with focus on Plug-in Hybrid Electric Vehicles (PHEV)
charging stations. The current system is able to simulate in real
time key elements of a smart grid such as: high speed power
electronics, distributed energy resources (DER), and
communication networks. A description of the platform for real
time simulation is presented along with the integration of
communication emulation; achieved through OPNET’s System
in the Loop (SITL) package. In addition, an introduction to
Networked Control Systems (NCS) is presented and a case study
of PHEV charging stations which displays the latest results
accomplished with the current setup.
I. INTRODUCTION
The smart grid refers to the digitalization of the power grid
in order to further improve it in terms of efficiency,
reliability, and automation. Some of the main characteristics
of this intelligent grid include two-way communication, self-
monitoring, adaptive, and allowing customer choices.
Although the necessary technology to achieve this
modernization of the power grid exists, sufficient research
and validation of the technologies and methods is necessary
in order to speed up their adoption [1][2]. However, real
environment tests are usually expensive and difficult to
achieve in a laboratory setting, for this reason, real time
hardware in the loop (HIL) simulation becomes a
fundamental tool in order to test controllers, power
electronics circuits, and communication methods to
effectively incorporate them in the power grid.
PHEVs are becoming dynamic elements not only requiring
large amounts of power from the grid, but also supplying
power in times when localized distribution faces overload
capacity [3]. In addition, PHEVs can supply supplementary
services to the grid such as frequency regulation by
controlling the active power flow [4]. Communications thus
play a key role in managing the distribution of energy. It is
necessary for a charging station to know the state of the grid
in terms of demand, pricing, and health in order to better
estimate the times for charging [5]. In [6], an overview of
different communication methods applicable to PHEV
charging stations such as Power Line Carriers (PLC), IEEE
802.15.4 (Zigbee), ZWave, and cellular networks were
summarized. Furthermore, a Zigbee based communication
platform for testing optimization parameters in a PHEV
charging station was proposed in [7].
The integration of communication in different applications
of power systems and power electronics can be considered
part of Networked Control Systems (NCS) [8]. A NCS is a
type of closed loop control in which there is communication
between the remote controller and the plant. NCS have found
many applications ranging from: robotics, aircraft,
automobiles, and now could be applied to power electronics
and power systems. Nevertheless, there are several
communication factors which affect the performance of NCS
such as: latency, unreliable communications (packet losses),
bandwidth and packet size constraints, and packet
disordering. In terms of power electronics, in [9] different
topologies for applications of interconnected converters,
while generalizing types of control requirements and delays
for each topology were studied. In [10], a wireless PWM
control for parallel dc-dc buck converters was modeled using
a state space representation, in which the characteristics of
communication delays were considered. Lastly, a method for
modeling wide area measuring systems (WAMS) in power
grids have been proposed in [11] for a NCS.
A co-simulation of real time HIL of continuous (power
systems) and discrete (communication) models, provides a
more tangible method for simulating real world NCS systems.
Focusing on PHEV charging stations, some examples of real
time HIL simulation for testing different characteristics of
PHEVs have been proposed in [12], where a model of a
PHEV was developed and run in real time to test a Vehicle
Control Unit (VCU). When integrating both power and
communication simulations, Nutaro et al. [13] developed a
software simulation of a 17 bus power network with
communication between the loads and generators;
investigating the effects of factors such as bandwidth and
latency on the overall system stability. This work provides an
example of combining discrete and continuous models to
study communication requirements and its influence to a
power system.
Although real time HIL simulation platforms have been
developed, most focus on one aspect in modeling, either
continuous (power electronics, power systems) or discrete
(communication networks). A joint effort is proposed in this
paper in order to effectively model these two types of
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