Dynamic Co-Simulation Methods for Combined Transmission-Distribution System With Integration Time Step Impact on Convergence

Abstract

Combined Transmission and Distribution Systems (CoTDS) simulation for power systems requires development of algorithms and software that are numerically stable and at the same time accurately simulate dynamic events that can occur in practical systems. The dynamic behavior of transmission and distribution systems are vastly different, especially with the increased deployment of distribution generation. The time scales of simulation can be orders of magnitude apart making the combined simulation extremely challenging. This has led to increased research in applying co-simulation techniques for integrated simulation of the two systems. In this paper, a rigorous mathematical analysis on convergence of numerical methods in co-simulation is presented. Two methods for cosimulation of CoTDS are proposed using parallel and series computation of the transmission system and distribution systems. Both these co-simulation methods are validated against total system simulation in a single time-domain simulation environment. The series computation co-simulation method is shown to have better numerical stability at larger integration time steps. The series computation co-simulation method is additionally validated against commercial EMTP software and the results show remarkable correspondence.

Transmission and distribution co‐simulation: a review and propositions

“…PETSc is a suite of high‐performance linear and non‐linear solvers that provides abstractions for efficiently building and solving DAEs. In [85], two methods for co‐simulation of a combined transmission and distribution system (CoTDS) are proposed using parallel and series computation. The CoTDS dynamic co‐simulation is further used for a detailed fault‐induced delayed voltage recovery (FIDVR) simulation of T&D. Besides, in this reference electro‐magnetic transient program (EMTP) software is used for validation of MATLAB results.…”

Advancements in co‐simulation techniques in combined transmission and distribution systems analysis

“…The objective is to validate the proposed co‐simulation approach against integrated system model. Modelling the complete T&D as stand‐alone system while keeping the details is possible in two commercially available software: DIgSILENT PowerFactory and PSS ® SINCAL [10]. In this paper, the integrated system is modelled in DIgSILENT.…”

“…Each feeder circuit on the distribution system is represented as a lumped ‘equivalent ’ balanced load. A balanced system and lumped load assumptions may lead to incorrect results and unacceptable errors especially when connected to long distribution feeders with high‐levels of distributed energy resources (DER) penetrations [8–10].…”

“…Owing to the requirements for combined T&D analysis, several methods have been proposed for combined modelling. The related literature can be classified into two broad categories: (i) using unified stand‐alone T&D model [11, 12], and (ii) using co‐simulation approach [9, 10, 13, 14]. While, unified stand‐alone models simulate T&D systems in one common software platform, in a co‐simulation approach, T&D systems are solved independently using their own solvers and the boundary variables (variables at PCC) are exchanged to model their mutual effects.…”

Studying impacts of communication system performance on dynamic stability of networked microgrid

“…The communication system operates at nanosecond time scales, whereas the power system dynamics may be modelled in millisecond time scales. This adds complexity and scalability issues to custom‐built co‐simulation platforms as the system grows [4, 17].…”