Tools for handling steady‐state under‐frequency regulation in isolated microgrids

Abstract

This study presents two approaches to handling under-frequency regulation in isolated microgrids. The first one is a governor power flow (PF) model in which the generators steady-state governor equations are modeled into a full Newton PF formulation resulting in an augmented sparse linearised system of equations to be solved at each iteration. As a result, it is possible to evaluate the under frequency problem in the case of microgrid islanding as well as to set the reference bus angle to evaluate the possibility of reconnection to the main grid. The second approach presents an optimal PF (OPF) formulation in which the generators governor equations are considered as additional equality constraints to determine the minimum amount of load shedding to keep the system frequency between specified limits. In both methods, it is also used an equation that provides voltage regulation in a droop-based control. The reactive power generation limits in the OPF approach are bounded by a proposed complementarity constraint-based method adapted for the generators' droop-controlled terminal voltage. The proposed approaches are evaluated and validated through the study of the EHV1 Network, a 61-bus 33/11-kV radial distribution system, and the New England test system. Ω L set of candidate buses to the load shedding p 1 , p 2 , p 3 active parameters of the ZIP model q 1 , q 2 , q 3 reactive parameters of the ZIP model K p f active load frequency dependency factor K q f reactive load frequency dependency factor V a k /V b k voltage auxiliary variables for complementarity constraints V k min /V k max min./max. voltage at bus k

Controle de frequência em redes de energia elétrica com alta penetração de renováveis por meio de cortes de carga e geração

“…A essa característica do sistema de se atingir um novo estado de equilíbrio em relação ao descompasso entre a potência gerada e consumida é denominada de regulação própria do sistema (La Gatta et al, 2019).…”

An interval power flow for unbalanced distribution systems based on the Three-Phase Current Injection Method

“…Note that the droop constant 𝐾 𝑓 is often referred to as the inverse of the generation unit statism and is generally less than 5% in the system base according to [32][33][34]. This constant may be associated mainly for rotating electrical machines and for Voltage Source Inverters (VSI) used for the connection of DG units into to distribution networks.…”

“…Uncertainties are modelled using interval arithmetic. Comparative analysis using different evaluation indices are performed for each case study being the simulations carried out using IEEE 13,33 and 69-bus test systems. Results are compared with MCS to demonstrate the viability and efficiency of the proposed method.…”

Alocação Ótima de Geradores Distribuídos em Microrredes Ilhadas Considerando Controle Droop de Frequência

“…Escolheu-se o AG por este ser um método bastante difundido na literatura. Ressalta-se que o FPO utilizado considera o efeito de droop de frequência e tensão nas unidades de geração distribuídas (La Gatta et al, 2019). A metodologia proposta é avaliada em uma microrrede ilhada de 33 barras (Hemmatpour et al, 2016).…”