ORIGINAL CONTRIBUTION Control of Electric Spring: A Lead–Lag Compensated Approach Mehul Dansinh Solanki 1 • S. K. Joshi 2 Received: 7 September 2020 / Accepted: 1 February 2021 / Published online: 1 March 2021 Ó The Institution of Engineers (India) 2021 Abstract Electric spring is a custom power device, pri- marily being used for the voltage stability/voltage regula- tion of a customer’s electrical installation. The idea of electric spring has primarily been derived from the concept of mechanical spring, to damp out the oscillations or variations in the voltage due to intermittency of renewable energy sources that are present in the distribution system. This paper explores the idea of electric spring through the development of its mathematical model and control strat- egy. A controller based on the Lead–Lag compensator for controlling the electric spring, which in turn is a power electronic converter and is controlling the voltage across the critical load by inserting a controlled voltage of an appropriate magnitude and phase in series with the non- critical load, is designed and validated through simulation. Keywords Custom power devices  Demand-side management  Flexible AC transmission system (FACTS)  Smart load  Voltage stability Introduction Quantum of electrical energy that is being consumed by a nation is an indicator of its progress , in socioeconomic terms. Conventionally, electrical energy generation has been heavily dependent on the fossil-based sources, viz. coal and diesel, which happens to be the prime source of emission of greenhouse gasses and causing pollution of the environment. Greater awareness and concern about envi- ronment has posed lot of restrictions on the emission of greenhouse gases, being proliferated by conventional generating sources, through stringent standards. There is a paradigm shift towards greater inclusion of non-polluting and green renewable energy sources (RES) in the grid along with the curtailment of polluting and emitting con- ventional fossil-based sources of electricity generation. To curb the menace of carbon emission, India has set an ambitious target of harnessing 60 GW of power through wind and 100 GW by solar, by the year 2022 and is planning to raise the share of RES by 60% of the total electricity generation, by the year 2030 [1, 2]. Bulk inclusion of RES leads to loss of stability of the electric grid due to its intermittency. Unpredictability of the RES causes market related issues, in the regime of restructured power system. Forgoing discussion reveals the fact that demand for electricity is increasing day by day which can only be catered by fossil-based bulk generating sources, is polluting the environment, on the other hand the cleaner option of the same, i.e., RES are causing pollution [3] of the electrical system itself. Area of demand-side management (DSM) [4] has been emerged as a method of reliably catering to the prevailing demand of electricity by managing the load rather than increasing the generation. DSM talks about peak load shaving or shedding, by deploying various DSM mecha- nisms, viz. on-off control, scheduling of delay-tolerant load, by providing battery storage, or by real-time pricing. Among these options, battery storage happens to be the best and most reliable option of DSM. In this approach of DSM, the bulk of energy demand is being catered by bulk & Mehul Dansinh Solanki solankimehuld@gmail.com 1 Electrical Engineering Department, Shantilal Shah Engineering College, Bhavnagar, India 2 Electrical Engineering Department, The Maharaja Sayajirao University of Baroda, Vadodara, India 123 J. Inst. Eng. India Ser. B (June 2021) 102(3):469–476 https://doi.org/10.1007/s40031-021-00553-1