Toward Coordinated Transmission and Distribution Operations

Abstract

Proliferation of smart grid technologies has enhanced observability and controllability of distribution systems. If coordinated with the transmission system, resources of both systems can be used more efficiently. This paper proposes a model to operate transmission and distribution systems in a coordinated manner. The proposed model is solved using a Surrogate Lagrangian Relaxation (SLR) approach. The computational performance of this approach is compared against existing methods (e.g. subgradient method). Finally, the usefulness of the proposed model and solution approach is demonstrated via numerical experiments on the illustrative example and IEEE benchmarks.Index Terms-Distribution system operations, transmission system operations, Surrogate Lagrangian Relaxation.

TSO and DSO with large‐scale distributed energy resources: A security constrained unit commitment coordinated solution

“…There are five different case studies carried out in this research as given below: Case 1 (118‐bus TS and 2 × 33‐bus DSs) Case 2 (118‐bus TS and 4 × 33‐bus DSs) Case 3 (118‐bus TS and 8 × 33‐bus DSs) Case 4 (118‐bus TS and 16 × 33‐bus DSs) Case 5 (118‐bus TS and 32 × 33‐bus DSs) Here, IEEE 118 Bus system contains 54 generators, which is used as TS system while each IEEE 33‐bus system contains five DERs, which is considered as DS system. It should be noted that the total demand (Pd) of system for different hours as shown in Table is scaled proportionally on all busses of TS . Moreover, for particular DS, load at relevant boundary bus of TS system connected to that DS is scaled proportionally on all busses of that DS.…”

“…For this case study, two DSs are considered for 24‐hour results evaluation. Without coordinator, TSO needs to solve its own OPF‐based SCUC problem (54 quadratic functions) along with two quadratic penalty functions (one for each DSO) and approximately more than 553 constraints. Increasing number of DSs will involve more quadratic penalty functions, which will create difficulty in solving TSO objective function.…”

“…In this case study, the number of DSs is increased to four because in real power systems. In absence of coordinator, TSO objective consists of its OPF‐based SCUC problem (54 quadratic functions) and four quadratic penalty functions, which are subjected to approximately 673 constraints, as it can clearly be seen that number of quadratic penalty functions and constraints are increasing with increase in number of DSs. While considering presence of coordinator in hierarchy, quadratic penalty functions are shifted from TSO to coordinator.…”

“…Here, proposed method involves nine quadratic penalty functions in coordinator objective function while satisfying 379 constraints . Moreover, we have reduced TSO's computational effort by omitting seven quadratic penalty functions and 478 constraints.…”

“…Increasing number of DSs also increases number of constraints and put burden on optimization and coordination algorithms. In case of no coordinator involved, TSO solves its own OPF‐based SCUC problem (54 quadratic functions) along with 16 quadratic penalty functions, which are subject to approximately 1393 constraints . Increase in number of constraints also effect solvability of solver used.…”