IEEE Electrification Magazine - June 2018 - 80

with rapidly changing system conditions during
power outages.

Co-CyPS: a Cross-layer Framework
in smart cities, as previously mentioned, security enhancement solutions such as a firewall can only provide
fine-grained protection for a single device, while individual devices can suffer from misconfigurations that result in
severe global conflicts. in addition, since communication
networks cannot tolerate even short-term transient outages, they must be continuously available; therefore, the system-wide properties of the electric grid must be integrated
and adequately maintained at all times. furthermore,
communication networks cannot afford complex security solutions due to their mission and time-critical
upper-layer power system applications. However, detection and mitigation techniques that are located only in
the power-system application layer would not be effective, especially when the system measurement redundancy is not sufficiently high. in this case, coordinated
attacks can be launched by intelligent attackers who ob-

tain electric grid information, such as grid topology and
transmission-line parameters. to bridge the gap between
the two directions, a cross-layer cyberphysical security
framework is necessary for electric grids in smart cities
with the goal of defending, detecting, and mitigating cyberthreats at the earliest possible stage. this can reduce
maintenance costs and optimize the availability for reliable power-system operations.
the cross-layer security framework can be implemented between communication network and power system
applications in smart cities, serving as the intermediate in
the co-cyPs. it will be deployed at the location where traffic aggregates, such as the control center gateway substation or microgrid control center. the schematic of the
framework is depicted in figure 4. according to the timeline, the cybersecurity enhancement framework is divided
into three phases: defense, detection, and mitigation.

Defense
the cyberattack defense scheme is implemented before
cyberattacks are launched. due to the limited resources

Power Distribution Grids
Microgrids
Physical-Security
Enhancement Resources
* Measurement Selection
* Grid Parameter Flexibility
Using Power Electronic Devices

Model-Based Anomaly
Detection in Power Application

Power-Distribution System
Contingency Analysis

Physical Anomaly Detection by
Power Electronic Converter

Cyberphysical
Interdependence Analysis

Cross-Layer
Moving Target
Defense

Cybersecurity Enhancement
Resources
* Access Control
* Authentication
* Identification
* Encryption

Cross-Layer
Cyberattacks Detection

Specification-Based Instruction
Detection

Real-Time Uncertainty-Aware
Network Verification

Communication Network

Figure 4. A cross-layer cybersecurity enhancement framework.

I EEE E l e c t r i f i c a t i on M a gaz ine / J UN E 2018

Emergency
Response Mitigation

Communication Network
Attack Propagation Analysis

Table of Contents for the Digital Edition of IEEE Electrification Magazine - June 2018