Power system stable operation requires, generating power of the system equivalent to the sum of all losses and affiliated load. Therefore, excess of load needs to be shed especially in islanding mode because generators are running at rated capacity. Different factors e.g. over current, low voltage level and frequency affect system performance but among them constant frequency is imperative for the steady functioning of power system because frequency is constant at every voltage level and hence, a dependable and reliable parameter to show imbalance situation. Additionally, active power deficit. System frequency is very sensitive to disturbance specially in islanding mode and is severely affected by the power imbalance between power generation and load which leads to overload or power generation loss. To shed excess load, U.F.L.S. (Under Frequency Load Shedding Scheme) is implemented. This research here presents Under Frequency Load Shedding Scheme for islanded distribution network. This proposed adaptive U.F.L.S scheme use swing equation to find power imbalance. It takes into consideration ROCOF (rate of change of frequency) and power imbalance and based on this data load is shed in single step which is better than cascading as other traditional U.F.L.S implements cascading steps and the response time to any magnitude of disturbance is also better than others. The adaptive U.F.L.S scheme is tested in Simscape Power System and Simulink (Software Packages in MATLAB) and the results shows that it stabilized the frequency thus stabilizing the system by shedding the right amount of imbalance load.
Nauman Ahmed Dr. Muhammad Naeem Arbab Hammad Israil Awan Shehla Noor "Adaptive Under-Frequency Load Shedding Scheme for Islanded Distribution Network based on Swing E International Journal of Engineering Works Vol. 7 Issue 03 PP. 183-188 March 2020 https://doi.org/10.34259/ijew.20.703183188
 Photovoltaic (PV) systems Characteristics of the utility interface, IEC 61727 Standard, December 2004.
 K. Christensen, “Technical Regulation for Thermal Power Station Units of 1.5 MW and higher,” Energinet.dk, Fredericia, Denmark, Regulation for grid connection TF 3.2.3, 2008.
 P. P. Barker and R. W. de Mello, “Determining the Impact of Distributed Generation on Power Systems 1 – Radial Distributed Systems,” IEEE Power Engineering Society Summer Meeting, vol. 3, pp. 1645-1656, 2000.
 S. P. Chowdhury, S. Chowdhury, P. A. Crossley, and C. T. Gaunt, “UK scenario of islanded operation of active distribution networks with renewable distributed generators,” International Journal of Electrical Power & Energy Systems 33, vol. 34, no. 12, pp. 2585-2591, 2011.
 R. A. Walling and N. W. Miller, “Distributed Generation Islanding Implications on Power System Dynamic Performance,” IEEE Power Engineering Society Summer Meeting, vol.1, pp. 92-96, 2002.
 IEEE Standard for Interconnecting Distributed Resources into Electric Power Systems, IEEE Standard 1547TM, 2003.
 Md. Quamrul, Ahsan, A. H. Chowdhury, S. S. Nawaz, I. H. Bhuyan, M. A. Haque, and H. Rahman, “Technique to Develop Auto Load Shedding and Islanding Scheme to Prevent Power System Blackout,” IEEE Transactions on Power Systems, pp. 198–205, 2012.
 X. Cao, I. Abdulhadi, C. Booth and G. Burt, “Defining the Role of Wide Area Adaptive Protection in Future Networks,” IEEE international Universities Power Engineering Conference (UPEC), pp.1-6, 2012.
 J. A. Laghari, H. Mokhlis, A. B. Halim, A. Bakar, M. Karimi and A. Shahriari, “A New Under-Frequency Load Shedding Scheme for Islanded Distribution Network” IEEE Innovative Smart Grid Technologies (ISGT), pp. 1–6, 2013.