Universal branch model for the solution of optimal power flows in hybrid AC/DC grids

Abstract

This paper presents a universal model formulation for solving Optimal Power Flows for hybrid AC/DC grids. The prowess of the new formulation is that it (i) provides a direct link between AC and DC parts of the grid allowing for solving the entire network within a unified frame of reference (not sequentially) and (ii) can realistically model any element within the AC/DC power grid, ranging from conventional AC transmission lines to multiple types of AC/DC interface devices such as Voltage Source Converters (VSC) by introducing additional control variables. The model is formulated in such a way that it does not make a distinction, from a mathematical perspective, between AC and DC elements and the ensuing optimal power flow (OPF) problem can be solved via model-based optimization solvers as a mathematical programming problem. Simulations carried out using a variety of non-linear gradient-based solvers in AIMMS © on a small contrived and a large realistic test system (modified PEGASE) clearly show that the universal model is on par with existing methodologies for solving OPFs both in accuracy of the solution and computational e ciency. Meanwhile, simulations carried out on a series of AC and AC/DC test systems show that the model is scalable and stays computationally tractable for larger system sizes without sacrificing convergence time. Reactive Power Q t Constraint v f Voltage "from" g P v dp Voltage Droop Constraint v t Voltage "to" g G sw VSC losses correction Constraint i f Current "from" h S 2 f Loadability Constraint "from" i t Current "to" h S 2 t Loadability Constraint "to" S f Complex Power "from" L S 2 L

Energy Management of Multi-Area Islanded Hybrid Microgrids: A Stochastic Approach

“…The TSO algorithm employs a random value 𝒓 𝒍 , to ensure equilibrium between the exploration (when r1 ≥ 0.5) and exploitation (when r1 < 0.5) of The TSO algorithm. The three stages are implemented using Equations ( 39) to (42).…”

Herramienta de simulación para el análisis de flujo óptimo clásico utilizando multiplicadores de Lagrange

“…El flujo óptimo de potencia conocido por sus siglas en inglés como OPF, es una extensión del problema de despacho económico de carga convencional (Chen et al 2016;Das 2017). El OPF, se utiliza para determinar la potencia que debe generar cada unidad del sistema de generación para cubrir la demanda al mínimo costo (Alvarez-Bustos et al 2021).…”

Optimum Operational Planning of Wind-Integrated Power Systems With Embedded Multi-Terminal High Voltage Direct Current Links Using The Flexible Universal Branch Model

“…The ESO therefore solves instances of OPF problems to account for any changes in the system's steady-state operating points (generators' resource dispatch, transformers' tap changer positions, and other controller actions) to plan the system operation in a reliable and economic manner ahead of real-time operation. Yet, developing accurate models that are capable of representing the control actions of VSC converters, especially in the context of operating in a meshed MT-HVDC network is still an area of active research [10,11].…”

“…Besides that, existing OPF formulations mostly employ a sequential methodology to independently solve the AC and DC elements of the hybrid networks. As a result, the governing equations for each model (AC and DC) are different [10].…”