Comparison of Advanced Microgrid Management Systems

Abstract

The advanced microgrid is pictured to be an essential part of the long run good grid attributable to its native intelligence, automation, ability, and distributed energy resources (DER) hosting capability. The enabling technology of advanced microgrids is that the microgrid management system (MGMS). during this article, we tend to discuss and review the idea of the MGMS and progressive solutions relating to centralized and distributed MGMSs within the primary, secondary, and tertiary levels, from that we tend to observe a general tendency toward decentralization. The distributed MGMS framework delivers not solely equivalent management functions because the centralized MGMS however conjointly bigger measurability, responsibility, and resiliency. we tend to severally discuss and demonstrate the distributed MGMS’s well-recognized improvement of responsibility and resiliency, mistreatment quantified indices, and numerical examples.

Introduction

As outlined by the U.S. Department of Energy, a microgrid could be a cluster of interconnected hundreds and DERs at intervals clearly outlined electrical boundaries that acts as one manageable entity with relevancy to the grid. A microgrid will connect and disconnect from the grid to modify it to control in either a grid-connected or islanded mode. However, because the industrial physics field acknowledges additional of this technology’s advantages, like DER integration, expense reduction, market participation, and increased responsibility and resiliency, the microgrid idea has evolved into what we tend to decision the advanced microgrid. With relevancy to the initial definition, rather than that specialize in its islanding capability to safeguard itself from outages and interruptions, the advanced microgrid more includes stress on generation and cargo management.

The advanced microgrid is in a position to actively balance the generation and demand, economically schedule and dispatch its generation resources, and attain high responsibility and resiliency. With these additional capabilities, the advanced microgrid are able to do multiple operational goals, like responsibility improvement, value reduction, and market participation. The vision is that advanced microgrids are going to be deployed within the distribution system to serve customers and host DERs. because the DER penetration level incessantly will increase, advanced microgrids can become an essential a part of the virtual power plants (VPPs) that backfeed power to the transmission to participate within the energy market. what is more, the advanced microgrids within the same distribution circuit may exchange power among themselves to extend responsibility and avoid transmission losses. The advanced microgrid can sure enough modification however the heritage transmission–distribution system interacts and have a good impact on the business model of utilities and aggregators.

The Advanced Microgrid's Key Element

The enabling technology that produces advanced microgrids potential is that the MGMS. the most MGMS management principles area unit model prophetic management, a multiagent system, distributed network management, cooperative management, and droop management. These techniques are enforced within the corresponding control layers and manage the microgrid’s parts, i.e., DERs, controllable hundreds, protection devices, and power quality devices. Microgrids area unit are usually hosted by the present distribution system through AN electrical association purpose called the purpose of con, the MGMS can economically operate common coupling (PCC). once the switch at the PCC is on, the MGMS can economically operate the microgrid by showing intelligence commercialism or importation power from the utility or can even participate within the energy market as a part of the VPP. During normal operation, the distribution management system (DMS) will request disconnection from the MGMS for load shedding or demand response purposes. Such missive of invitation can even be initiated by the MGMS to avoid disruptions caused by utility grid faults or natural disasters. once the switch at the PCC is off, the MGMS will coordinate the offered DERs to balance local generation and demand, while monitoring the host grid standing for reconnection.The main MGMS functions area unit summarized in Table one, whereas Figure one highlights the duration and hierarchy of each control operation. per their necessities, these management functions are usually categorized into three levels: primary, secondary, and tertiary, that is mostly referred to as a ranked MGMS. The fast response, device-level management tends to have a lower management hierarchy, whereas slower, system-level controls tend to own higher management hierarchies.

Primary Control

The primary control directly interacts with the devices within the microgrid and responds to system dynamics and transients. It is the bottom management layer that features the quickest response. Since the DERs square measure geographically distributed, the communications at the first level square measure typically unbroken to a minimum. Typically, for associate degree ac microgrid, the inertia characteristic of synchronous generators is electronically emulated in these VSIs to face up to frequency and voltage deviations.

The VSI has 2 management stages: electrical converter output management and power-sharing management:

1. electrical converter output management: The electrical converter output control directly manages the voltage and current output of the electrical converter. a typical approach is to implement associate degree outer voltage loop and inner current loop with proportional and integral controllers to control the voltage and current output.
2. Power-sharing control: the facility sharing control manages the output of individual energy resources within the microgrid to serve the , whereas keeping the system frequency and voltage in a suitable vary.

Secondary Control

The MGMS’s secondary control is accountable for the economical and reliable operation of the microgrid. The most management functions embody automatic generation management and therefore the microgrid energy management system (EMS). The secondary controller resets the frequency and voltage deviations of the droop-controlled VSIs and generators, then assigns to them new optimum long-run set points calculated from the microgrid EMS. The main objective of the EMS is to reduce the microgrid’s operational value and maximize its responsibility. In terms of the economic toll, the value operate typically consists of all or a set of the fuel cost, power bill, maintenance value, closure and startup value, emissions, and welfare and battery maintenance value, closure and startup value, emissions, and welfare and battery constrained improvement typically contains the cost of the loss of load. and therefore the needed responsibility indices square measure typically developed as constraints of the improvement downside. These square measure typically the generation and demand balance, power cable limit, energy storage capability limit, responsibility indices demand, and power ratings of the manageable generations. The manageable variable of the improvement downside is that the power output of the dispatchable units and therefore the call variables that mirror the unit’s on-off standing.

Tertiary Control

Tertiary management is that the highest MGMS level. It coordinates with neighboring microgrids, DERMSs, and DMSs. Typical tertiary management functions embody transmission system real power and reactive power support, subsidiary services, intentional islanding, and so forth. The duration of tertiary management is on the order of minutes or is event-driven. Conventionally, tertiary control is recognized as a scheme of the utility DMS, thus it's not thought-about a part of the MGMS.Within the distribution system, the microgrids, grid-hosted DERs, and manageable hundreds are mass to create a VPP that interfaces with the transmission through its feeder head, conjointly referred to as a grid support purpose (GSP), and provides real power and reactive power support to the majority grid. The VPP will give transmission primary frequency support, reactive power support, and energy market participation. The VPP is primarily managed by the utility-side

DERMS

The DERMS in associate degree of itself solves an improvement downside to maximize the profit by collaborating within the energy market, that is typically a centralized management answer. However, because the range of DERs, manageable hundreds, and microgrids continues to grow, this centralized controller can eventually be full. within the close to future, the MGMS is predicted to possess a bearing counterpart within the tertiary level to collaboratively solve the VPP improvement downside during a distributed manner.

Reliability Enhancement of The Distributed MGMS

The responsibility and resiliency advantages of microgrids square measure well known, and researchers ubiquitously report within the literature an equivalent superior qualities of the distributed MGMS. however the definitions of responsibility and resiliency square measure rather ambiguous. Moreover, the advantages ensuing from microgrid energy adequacy and from the distributed MGMS framework square measure often left dedifferentiated. The idea of responsibility places additional stress on the probability of device failure and therefore the resultant incidents. higher responsibility indicates the system is a smaller amount possible to fail or malfunction. and therefore the idea of resiliency emphasizes the system’s ability to mitigate associate degree live through adversity. during this section, we tend to discuss severally the ideas of responsibility and resiliency, and we distinguish and demonstrate the additional responsibility and resiliency options of the distributed MGMS mistreatment quantified indices and numerical examples. Current microgrid responsibility analysis is mostly targeted on the physical layer parts e.g., overhead lines, cables, transformers, circuit breakers, and therefore the DER itself. Investigators typically study microgrid responsibility during a renewable-based and islanding environment. These works in the main relate to the adequacy of DERs to balance the load. However, the controller failures within the centralized and distributed MGMS frameworks square measure nonetheless to be analyzed. In alternative analysis, like and, responsibility is often thought-about and developed as a part of the constraints for microgrid style and designing. For distributed MGMS analysis, responsibility enhancements square measure typically qualitatively conferred. Hence, this section aims to use a numerical example to quantify and demonstrate the responsibility variations between centralized and distributed MGMSs within the microgrid.

Conclusion

The distributed MGMS framework delivers not solely equivalent management functions because the centralized one however conjointly offers nice measurability, reliability, and resiliency. Moreover, we tend to mention the ideas of responsibility and resiliency and incontestable the additional responsibility and resiliency options of the distributed MGMS mistreatment quantified indices and numerical examples. In terms of responsibility, the numerical examples that we tend to conferred within the section “Reliability and Resiliency improvement of the Distributed MGMS” incontestable that, employing a controller with an equivalent responsibility level, away superior system-level responsibility is achieved with the distributed MGMS framework. in addition, the distributed MGMS answer will deliver an equivalent system-level responsibility because of the centralized answer, with a lot of less reliable controllers. For resiliency, we tend to incontestable associate degree attack-resilient distributed management technique that ensures resilient operation within the presence of sudden adversaries. Thus, system-level resiliency is achieved below the distributed MGMS framework.