An overview of DC microgrid operation and control (2024)

FAQs

What are the control strategies of DC microgrid? ›

However coordinate control needs some line of communication between the units in order to achieve the coordination in the dc MGs. According to the communication method, there are three basic control strategies which are distributed control, centralized control, and decentralized control.

In DC microgrid structure, sources with DC output are connected to DC bus directly, whereas sources with AC output are interfaced to DC bus through AC/DC converter [8]. As the number of DC-generating renewable energy sources is higher as compared to AC-generating sources, lesser converter units are required.

Microgrid operation. Voltage and frequency regulation, real and reactive power control, load forecasting and scheduling, microgrid monitoring, protection, and black start are all part of microgrid control.

The primary level is controlled by the bus voltage in a microgrid. The difference in voltages that are produced will be reduced at the secondary level, which guarantees smoother operation at the tertiary level. The present flow from/to an external DC source is controlled by the tertiary power [12].

Conventionally, the dc-dc converters have been controlled by linear voltage mode and current mode control methods. These controllers offer advantages such as fixed switching frequencies and zero steady-state error and gives a better small-signal performance at the designed operating point.

Though there is a variety in the classification and definitions of microgrid control, the widely accepted hierarchical structure of microgrid control includes primary, secondary, and tertiary control levels. The tertiary control level principally focuses on system level scheduling, optimization, and energy management.

Through the comparison of both configurations, the bipolar DC microgrid presented several advantages, such as a higher number of voltage levels (two instead of one), increased efficiency and a power supply with increased quality [17].

Centralized management, control, and backup power for reduced operating expense, improved reliability, and lower energy consumption. Ability to intelligently share power across various building loads for lowering the amount of incoming power required.

A DC micro grid system has been proposed as a power network that enables the introduction of a large amount of solar energy using distributed photovoltaic generation units.

What is microgrid in simple words? ›

A microgrid is a group of interconnected loads and distributed energy resources that acts as a single controllable entity with respect to the grid. It can connect and disconnect from the grid to operate in grid-connected or island mode.

A microgrid is a local energy system which incorporates three key components; Generation, Storage and Demand all within a bounded and controlled network. It may or may not be connected to the grid. Different end-users have a range of requirements from their energy supply systems.

Primary control copes with the preliminary power sharing control and current/voltage regulations [8]. Secondary control, a higher level than primary, deals with the voltage compensation and sharing performance enhancement [9].

DC microgrid fault types can be divided into converter fault, DC bus fault, and branch line fault according to fault position, and can be specifically divided into positive grounding fault, negative grounding fault, and inter pole short circuit fault according to fault polarity [12], [13], [14], [15].

In a typical electrical grid, the basics of the voltage control are provided by the synchronous generators. These generators are equipped with automatic voltage regulators that adjust the excitation field keeping the voltage at the generator's terminals within the target range.

There are two kinds of control strategies used in DC choppers namely time ratio control and current limit control. In all situations, the average value of the o/p voltage can be changed. The differences between these two can be discussed below.

Droop control method is a well known method in DC microgrids, where the reference voltage of each source is calculated using its nominal output voltage, output current and a droop coefficient.