## 1 Introduction
[26] modeled ECPSs and quantized the vulnerability of the systems using the theory of complex networks. [PERSON] et al. [27] described the relationship of communication networks and power grids with multiple support-dependence relations. [PERSON] et al. [28] summarized the effectiveness indicators of power grids based on the topology information of ECPSs. [PERSON] et al. [29] measured the damage of cyber attacks in terms of the load curtailment and addressed the problem of the transmission system security with an optimization model. [PERSON] et al. [30] considered ECPSs multi-agent dynamic systems and proposed a flocking-based paradigm for security control. [PERSON] et al. [31] introduced a two-player zero-sum game between the adversary and the defender to evaluate the performance of defense mechanisms with different network configurations. Although these models can be used to assess the vulnerability of ECPSs, the theory of complex networks can only be used to analyze the topological characteristics of ECPSs, not considering the electrical information. State equations of generators do not fit for analyzing large-scale transmission grids. In the third approach, scholars concentrate on the development of smart grid cyber-physical system testbeds for vulnerability analyses. [PERSON] et al. [32] presented a cyber-physical power system framework based on the service-oriented architecture for experimental results. [PERSON] et al. [33] provided a simulation environment to model the process of supervisory control and data acquisition (SCADA) system vulnerability exploitations. In Reference [34], the Optimized Network Engineering Tools (OPNET) was extended to simulate wide-area communication networks in power systemswhere the power system dynamic simulation was simplified as a virtual demander. NS-2 [35] was also a popular and open source discrete-event simulator developed to facilitate the simulation of communication networks. In some of the testbeds [36; 37], actual data acquisition and actuator components (remote terminal unit (RTU), phasor measurement unit (PMU), and intelligent electronic device (IED)) were integrated with the power system simulators using middleware to enable hardware-in-the-loop (HIL) simulations. In summary, different simulation platforms and approaches integrating existing simulators have been proposed with different purposes and limitations. Several simulation paradigms of communication networks (such as time delay or packet loss) are no longer a concern in smart grids. Our research focuses on establishing a complete evaluation procedure of vulnerability analysis with ECPSs considering cyber attacks. For this purpose, we have developed our study from three aspects in Figure 1: model, platform, and assessment. The model approach is suitable for large-scale systems (as shown in References [13; 38]). In this paper, we will first go on with the study of the simulation platform with advantages of easy programming, fast calculation, and no damage to systems, and secondly, propose a convincing and comprehensive vulnerability assessment from five aspects. This paper has two contributions. The first is a MATLAB-based platform (R2013a, The MathWorks, Inc., Natick, MA, USA, 2013) for the offline simulation and analysis of the vulnerability of ECPSs. This platform has advantages of easy programming, fast calculation, and no damage to systems. The protection procedure of ECPSs under cyber attacks and algorithms about detection and protection when dealing with a cascading failure are embedded by functions. The proposed simulation platform has great compatibility and expansibility in which operators can easily change the algorithm without changing the inputs.