Interactive Distribution Expansion and Measurement Planning Considering Controlled Partitioning

To model interactions among system expansion, controlled partitioning (CP), and observability, an integrated multi-period framework is developed in this paper for simultaneous planning of distribution systems and measurements with CP constraints (DSMP-CP) in unbalanced multi-phase networks. The proposed framework, employing the network AC model, is formulated as a mixed-integer quadratically-constrained programing problem. This problem minimizes investment costs (including the costs of feeder reinforcement, distributed generation (DG) placement, and allocation of micro-phasor measurement units and their measuring channels) and operation costs (including the costs of DG operation, energy purchased from the upstream grid (UG), re-dispatching of DG and UG injections, and energy curtailment). A phase-based observability function is also introduced to ensure the observability of all phases of buses. Furthermore, the concept of zero-injection (ZI) property is proposed for ZI groups considering physical connections and mutual impedances among phases to enhance observability efficiency and avoid suboptimal solutions. To enhance problem tractability and eliminate linearization errors, a duality-based solution approach is proposed employing an exactness loop with recursive re-linearization. The performance of the proposed framework is evaluated by testing it on the unbalanced IEEE 111-node and 256-node distribution test systems.