Optimal reactive power planning in an industrial microgrid: a case study of Urmia Petrochemical plant

• An insightful reactive power compensation in real MGs by spatio-temporal constraints. • Maintaining problem optimality considering the objectives and constraints. • Benchmarking centralized and distributed reactive power compensation for industrial MGs. • Simultaneous voltage quality improvement, power losses minimization, and power factor correction during capacitor placement. In real industrial microgrids (MGs), the length of the primary delivery feeder to the connection point of the main substation is sometimes long. This reduces the power factor and increases reactive power absorption along the primary delivery feeder from the external network. Besides, the giant induction electro-motors as the working horse of industries requires remarkable amounts of reactive power for electro-mechanical energy conversions. To reduce power losses and operating costs of the MG as well as to improve the voltage quality, this study aims at providing an insightful model for optimal placement and sizing of reactive power compensation capacitors in an industrial MG. In the presented model, the objective function considers voltage profile and network power factor improvement at the MG connection point. Also, it realizes power flow equations within which all operational security constraints are considered. Various reactive power compensation strategies including distributed group compensation, centralized compensation at the main substation, and distributed compensation along the primary delivery feeder are scrutinized. A real industrial MG, say as Urmia Petrochemical plant, is considered in numerical validations. The obtained results in each scenario are discussed in depth. As seen, the best performance is obtained when the optimal location and sizing of capacitors are simultaneously determined at the main buses of the industrial plants, at the main substation of the MG, and alongside the primary delivery feeder. In this way, 74.81% improvement in power losses reduction, 1.3% lower active power import from the main grid, 23.5% improvement in power factor, and 37.5% improvement in network voltage deviation summation are seen in this case compared to the base case.