**Reactive Power Management Considering Stochastic Optimization under the Portuguese Reactive Power Policy Applied to DER in Distribution Networks**

**Tiago Abreu 1, Tiago Soares 1,\*, Leonel Carvalho 1, Hugo Morais 2, Tiago Simão <sup>3</sup> and Miguel Louro <sup>3</sup>**


Received: 1 October 2019; Accepted: 21 October 2019; Published: 23 October 2019

**Abstract:** Challenges in the coordination between the transmission system operator (TSO) and the distribution system operator (DSO) have risen continuously with the integration of distributed energy resources (DER). These technologies have the possibility to provide reactive power support for system operators. Considering the Portuguese reactive power policy as an example of the regulatory framework, this paper proposes a methodology for proactive reactive power management of the DSO using the renewable energy sources (RES) considering forecast uncertainty available in the distribution system. The proposed method applies a stochastic sequential alternative current (AC)-optimal power flow (SOPF) that returns trustworthy solutions for the DSO and optimizes the use of reactive power between the DSO and DER. The method is validated using a 37-bus distribution network considering real data. Results proved that the method improves the reactive power management by taking advantage of the full capabilities of the DER and by reducing the injection of reactive power by the TSO in the distribution network and, therefore, reducing losses.

**Keywords:** decision-aid; distributed energy resources; distribution system operator; reactive power management; uncertainty
