Surge Protection for DC Microgrids


DC Microgrid

OVERVIEW

Today's increased reliance on very sensitive electronics makes surge protection an important topic for DC Microgrids. The Insurance Institute for Business & Home Safety study found that $26 billion dollars was lost due to non-lightning power surges. In addition, there are about 25 million lightning strikes in the US each year that cause between $650M to $1B in losses according to the Insurance Information Institute, State Farm©.


Wind Turbine

This page discusses how to best protect your DC Microgrid and all the associated components like Inverters, Power Conversion Modules, Power Panels, Energy Storage Systems or ESS, Battery Chargers, Solar Tracking Modules, Sensors and other alternative energy sources.

Selecting SPD for PV Microgrids

NEC/NFPA 70 require that Surge Protective Devices (SPDs) shall be UL1449 Listed. This means selecting a surge protector is easier than it has ever been. There are only a few choices available for SPDs that are UL Listed for any of the most commonly used surge standards including UL1449 5th Edition, UL497B, and UL497E.

Main Service Panel | Power Conversion Cabinet | Battery Storage Cabinet | Control & Monitoring Cabinet

Recommended SPD for Main Service Panel

Location	Equipment	System	Surge Protector Model#	Link
	Main Panelboard	480Vac	MDS750E-480D

Recommended SPD for Power Conversion Cabinet

Equipment	System	Surge Protector Model#
Power Conversion System Cabinet	480Vac Power Input	DS74US-480D
	P/S 120-240Vac Power Input	DS72US-230S/G
	DC/DC Converter 1500Vdc Power Input	DS50PVS-1500/51
	P/S 24Vdc Power Output	DS220S-24DC
	Control Unit Ethernet Cat 6A	MJ8-C6A
	Wireless	P8AX09-6G-N/FF
	4-20mA	DLA-24D3

Recommended SPD for Battery Storage Cabinet

Location	Equipment	System	Surge Protector Model#	Link
	Battery Storage Cabinet	24-1500Vdc Power Input	DS220S-24DC DS50PVS-1500/51
		Communications Ethernet Cat 6A	MJ8-C6A

Recommended SPD for Control and Monitoring Cabinet

Equipment	System	Surge Protector Model#
Control & Monitoring Cabinet	24Vdc Power Input	DS220S-24DC
	Network Switch Ethernet Cat 6A	MJ8-C6A
	Network Switch POE Cat. 6A	MJ8-POE-C6A
	Energy Mgnt RS232	DLA-12D3
	Energy Mgnt 4-20mA	DLA-24D3
	SCADA Wireless	P8AX09-6G-N/FF

Types of Microgrids
Off-grid/remote
Off-grid microgrids always operate in island mode due to a lack of electrical infrastructure from the utility grid. In the past, these microgrids ran mainly on diesel or propane, but today, renewable power sources such as solar are not only more common, but also sustainable, economic options when paired with a battery storage system.
Grid-connected
As defined by the U.S. Department of Energy, grid-connected microgrids are a group of interconnected customer loads and distributed energy resources within clearly defined electrical boundaries. These microgrids act as individual, controlled entities that can connect and disconnect from the primary grid.
Networked
Also known as nested microgrids, networked microgrids serve a large geographic area. They consist of separate distributed energy resources that are connected to the same utility grid circuit segment. These microgrids are usually managed by a supervisory control system that coordinates all member segments.

Microgrid Technologies
Micro-Hydropower System
A micro-hydropower system consists of a turbine, pump, or waterwheel to turn the energy of flowing water into rotational energy, which then becomes electricity. A micro-hydropower system can generate as much as 100 kilowatts of electricity, while a 10-kilowatt system can generally power a large home, small resort, or hobby farm.
Solar Photovoltaic System
A photovoltaic (PV) system comprises a series of solar panels, inverter, and other hardware that use energy from the sun to generate electricity. PV systems can range anywhere in size from small, portable systems to utility-scale generation plants.
Combined Heat and Power System (Cogen)
Also known as cogeneration, combined heat and power (CHP) systems generate electricity and capture the heat for use as thermal energy, such as steam or hot water. This thermal energy can then be used for space heating, cooling, domestic hot water, and industrial processes. The two most common CHP configurations are combustion turbine (or reciprocating engine) with a heat recovery unit or steam boiler with a steam turbine.
Biomass System
Biomass refers to organic material that can be processed and burned to produce energy. Direct-fired combustion systems burn biomass to generate high-pressure steam. The high-pressure steam produced by these plants then drives a turbine generator to make electricity. After use by the turbine, the lower pressure steam can heat a building. Biomass systems work great in colder climates or in buildings that have a constant need for hot water.
Battery Energy Storage System
A battery energy storage system (BESS) stores electrical energy that can be used at a later time. The system’s converter charges and discharges batteries to store or provide power. BESS systems use a controller to perform tasks such as peak shaving and load shifting, or serve as a temporary back-up power source based on system needs. They pair well with intermediate generation sources like solar photovoltaic systems.
Hydrogen Storage and Generation
Hydrogen is an emerging storage source that has gained viability in recent years. This system uses excess energy to power an electrolyzer and generate hydrogen from water. The hydrogen can be stored and used to create energy at a later date using either a fuel cell or gas turbine. While not as efficient as a battery storage system, it can serve as an excellent method to store energy for long durations.
Pumped Hydro Storage
Pumped hydro is a form of energy storage that uses a turbine in conjunction with an upper and lower reservoir. During times of excess energy production, the turbines can spin backward, pumping water to an upper reservoir. When there’s a need for more energy on the grid, this process is reversed so water runs from the upper reservoir to the lower reservoir while passing through the turbine, causing it to spin and generate power. This storage method accounts for roughly 95% of the utility-scale storage in the United States.