The method is fast and quite accurate. Also, the ML-based
detection algorithm works in a non-invasive manner as it does
not interfere with the normal power system operation. In a
power grid, measurement data from some metering instru-
ments might be missing occasionally due to communication
loss or faulty instruments. A trained ML-model might still be
able to correctly classify a set of measurement data as normal
or malicious even when parts of the dataset are missing. We
leverage such characteristics of the ML method in our IDS
to detect attacks, especially the control mode related attacks
on the PV system. We simulate the PV control modes to run
power flow using the power simulator MATPOWER [6] and
generate exhaustive datsets for our study. We test several ML
algorithms and compare their performance. The contributions
of our work can be summarized as below:
•We give one of the first studies where simultaneous
attacks on PVs operating in different control modes
are considered, under a strong attacker model which
assumes capability of manipulating individual PV bus
measurements to remain hidden.
•For the various configurations, we create several base-
line datasets using a standard test distribution network
with real-world PV generation and load demand data
(where small errors of the energy meter readings are
unavoidable). We make these datasets publicly available
to facilitate further research in this direction.
•We evaluate the performance of many ML algorithms by
conducting extensive experiments including cases where
parts of measurement data are missing. The results show
that the ML-based techniques, specifically multi-layer
perceptron and random forest algorithms are effective and
efficient in detecting attacks on various PV control modes
(accuracy of around 95% even with missing data).
II. LITERATURE REVIEW
Cyberattack scenarios in the broader context of smart grid
have been well studied in the literature. Study on DER
integrated grids has also been popular among the energy
and cybersecurity research communities. Qi et al. [5] sug-
gested a holistic framework for defence against cyberattcks
in a network with high DER penetrations. The resilience
design aspects at cyber, physical device and utility levels
had been broadly discussed. In the same vein, Johnson et
al. [7] proposed engineering design control of the DER
devices and enclaving (i.e., segmentation) of the network with
several DERs to enhance the cyberattack resiliency. In [8], the
authors summarized the current industry practices for DER
cybersecurity and also suggested some strategies to improve
the security postures. Specifically for IDS, signature-based
and behavioural-based solutions were studied in [9] to detect
few types of attacks on PV inverters. For voltage control
manipulation in low voltage distribution grid, [10] gives a
contextual anomaly detection method based on an artificial
neural network. Chavez et al. [11] showed the importance of
physical system features, in addition to the network traffic
features, to identify certain types of attacks in a distribution
network. They collect and use a combination of cyber-security
data and power system and control information to propose a
hybrid IDS for DER systems. Unsupervised [2] ML algorithms
have been tested on a proposed edge-based IDS for PV system
security. In [4], a more conventional approach of supervised
learning ML methods were used to detect attacks, considering
synchronized data from PV systems.
In a different direction, Li et al. [12] use raw electrical
waveform data and a high-dimensional data-driven approach to
detect and identify cyber-physical attacks in distribution power
grids with PVs. Another approach that has been widely studied
in the power system context is the application of physics-based
techniques for attack detection [13], [14]. However, these
solutions rely quite heavily on the availability and accuracy of
all measurement data. For cases with missing measurements
or meter reading errors, the performance and accuracy of such
solutions would be limited.
Overall, most of these works discussed here focus on single
operating mode and the attacker doesn’t particularly focus on
remaining hidden. In contrast, here we consider simultaneous
attacks on PVs operating in different control modes where the
attacker manipulates PV bus measurements to remain hidden.
III. THREAT MODEL AND ATTACK MODES
Before we discuss in detail the possible threats on PV unit
operations, we briefly describe the various possible operating
modes of a PV unit. Once the attacker gets control, it actively
tries to stay hidden by manipulating the measurement data of
the bus associated with the DER by sending data as if the
DER were not attacked. As such, an analysis of individual PV
bus measurements wouldn’t reveal any attack.
A. PV Operating Modes
We consider three PV operating modes, namely, limit active
power mode (Max P), Constant power factor (PF) mode, and
voltage-reactive power mode (volt-var). Due to variability in
solar irradiance, the active power output from the PV unit
changes and it is limited by the capacity of PV unit and
associated inverters.
In limit active power mode (Max P), a DER is set to deliver
a defined maximum amount of active power. In constant power
factor (PF) mode, the active power output is proportional to
the reactive power output. Lastly, the voltage-reactive power
mode (volt-var mode) of operation is an important regulation
mode where the DER reactive power output is a function of the
voltage at the point of common coupling (PCC) or the DER
terminal for a standalone unit. PV inverter can be set to operate
at any characteristics between the most and least aggressive
curves defined as per UL 1741, and depicted in Fig. 1. Our
default setting (blue line in Fig. 1) is as per the interconnection
Rule 21 of California Public Utilities Commission, and also
per the PV inverter application guide [15].
B. PV Attack Modes
As the penetration of DERs including PVs into the grid is
becoming high, any maloperation in the PV control modes