Centralized Control of Distributed Single-Phase Inverters Arbitrarily Connected to Three-Phase Four-Wire Microgrids

Abstract

This paper proposes an effective technique to control the power flow among different phases of a three-phase four-wire distribution power system by means of single-phase converters arbitrarily connected among the phases. The aim is to enhance the power quality at the point-of-common-coupling of a microgrid, improve voltage profile through the lines, and reduce the overall distribution losses. The technique is based on a master/slave organization where the distributed single-phase converters act as slave units driven by a centralized master controller. Active, reactive, and unbalance power terms are processed by the master controller and shared proportionally among distributed energy resources to achieve the compensation target at the point-of-common-coupling. The proposed control technique is evaluated in simulation considering the model of a real urban power distribution grid under non-sinusoidal and asymmetrical voltage conditions. The main results, concerning both steady-state and transient conditions, are finally reported and discussed

Multiobjective approach for power flow and unbalance control in low-voltage networks considering distributed energy resources

“…To regulate the power flow in each m-phase (m = a, b and c) of the network, PBC uses certain coefficients representing the percentage of actual power capability to be dispatched by DERs, called scalar coefficients (αPm, αQm). These coefficients are calculated in the CC and then broadcasted to every DER participating in the PBC [3].…”

“…Thereupon, CC broadcasts scalar coefficients (αPm, αQm) to every DER. For a proper operation of the power unbalance compensation, it is necessary knowing the m-phase to which each DER is connected, so the DER can send a request to the CC and then update a phase list [3].…”

“…), energy storage, and a single-or three-phase inverter (e.g., DC-AC converter) that performs the interconnection between the primary energy source (PES) and the distribution network. Besides injecting active power into the network, DERs can perform ancillary services in order to enhance the system power quality and reliability [2], [3], [4]. Some of these ancillary services are: voltage support under low-voltage ride-through, reactive compensation, harmonic mitigation, and power unbalance reduction, mainly due to load unbalance and intermittent power generation from single-phase converters.…”

“…It occurs because the distributed units are arbitrarily connected to the grid worsening the power unbalance. In [3] it was shown how to distributedly compensate load unbalance through coordinating single-phase DERs arbitrarily connected to a three-phase network. To optimize the use of energy, a generation energy cost dispatch system was proposed in [6] and [7], but no energy quality issues were explored.…”

Validação Experimental de uma Microrrede com Controle Centralizado e Despachável

“…Métodos de operação centralizada de microrredes, em contrapartida, mesmo sendo dependentes de infraestrutura de comunicação e requererem algoritmos complexos de controle, apresentam maior robustez às condições indesejáveis citadas [8]. Ademais, com o advento de tecnologias de informação e comunicação (TIC) direcionadas à área de energia [9], estratégias de controle centralizado têm propiciado soluções mais aprimoradas e adequadas à coordenação de agentes distribuídos em redes elétricas.…”