In this paper, we consider the Continuous Double Auction (CDA) scheme as a comprehensive power resource allocation approach on micro-grids. Users of CDA schemes are typically self-interested and so work to maximize self-profit. Meanwhile, security in CDAs has received limited attention, with little to no theoretical or experimental evidence demonstrating how an adversary cheats to gain excess energy or derive economic benefits. We identify two forms of cheating realised by changing the trading agent (TA) strategy of some of the agents in a homogeneous CDA scheme. In one case an adversary gains control and degrades other trading agents' strategies to gain more surplus. While in the other, K colluding trading agents employ an automated coordinated approach to changing their TA strategies to maximize surplus power gains. We propose an exception handling mechanism that makes use of allocative efficiency and message overheads to detect and mitigate cheating forms.