Hierarchical controls selection based on PV penetrations for voltage rise mitigation in a LV distribution network

• This paper proposes a cost-effective technique to enhance PV integration into DNs.
• Hierarchical control is proposed for voltage regulation based on PV penetration (%).
• Power sharing among unity pf and smart VSI is included in the proposed controller.

In recent years, the penetration level of distributed energy resources (DER) in the low voltage (LV) networks are increasing rapidly which has resulted in causing the voltage rise problem, even at the far end customer point in distribution networks (DNs). This paper presents a coordinated hierarchical controls selection method for mitigating the overvoltage problem using available resources in DNs, for example, static synchronous compensators (STATCOM) and battery energy storage (BES) systems. The proposed method recommends the installation of new control devices, such as photovoltaic (PV) smart voltage source inverter (VSI) with reactive power compensation capability, residential BES installations, and power sharing among neighboring distributed generator (DG) units depending on PV penetration levels at the LV network. The requirements of the proposed installation of the compensation devices are based on three criteria: (i) higher PV penetration scenarios; (ii) satisfying relevant standards; and (iii) economic perspectives. The interactions among standard VSI (operated at unity power factor (pf)) and smart VSI (variable pf) are also considered in the proposed method to mitigate the voltage rise problems. The results show that only after exceeding certain PV penetrations, the LV network requires a coordinated operation from STATCOM/BES and advanced compensation devices to sustain terminal voltages within permissible (±6%) limits. The proposed method is verified with extensive case studies utilizing real PV irradiance and customer loads data with nonlinear dynamic DER models connected with an urban LV network in the PSCAD/EMTDC software environment.