**5. The implementation of recloser devices for autoconfiguration and automatic connecting/disconnecting decisions, in order to switch on the backup power supply**

To implement the above basic functions and the control algorithm, the system also integrates

**Figure 7.** Electric power diagram for switching to backup power supply in the case of a low-voltage smart microgrid using an electric generator set and the photovoltaic panels (courtesy of Sirius Trading & Services srl, Romania).

**a.** Monitoring the presence of voltage on the three sources (three-phase public grid, an elec-

**b.** Monitoring the state signals of the electric power generator set, such as the presence and level of fuel, the good operation of the filter, the command temperature of the shock, as

**c.** Connecting/disconnecting of the electric power generator set when the three-phase public

**d.** Checking confirmation commands from the circuit's commutation wires and providing

**e.** Counting the number of three-phase public grid voltage drops, disconnection time of the public grid, the number of connections, and time of operation per electric generator set

well as the heating resistor's temperature of the fuel (command).

the following additional functions:

90 Smart Microgrids

tric generator set and photovoltaic panels).

grid is available/unavailable, respectively.

alternatives if commands are unconfirmed.

As smart grids are composed of sensitive equipment at voltage interruptions in increasing proportion, higher-power-quality issues have become increasingly important. In order to reduce the rate of long-term interruptions and thus improve the quality of energy, for medium voltage (MV) distribution networks, it is proposed to use the recloser devices. Thus, it can prevent long outages by eliminating temporary malfunctions, before the fuses are operating in the system. Reclosers also offer control, measurement, automation, and telecommunication capabilities. This makes it possible to control in real time the intelligent network that now allows maneuvers for various purposes. Reclosers also provide consecutive automatic

**Figure 8.** The Tavrida electric recloser concept, up to 40.5 kV (RMS) rated maximum voltage and up to 1250 A (RMS) rated continuous current [10] (courtesy of Tavrida electric).

closing cycles to eliminate transient faults and minimize network interruption. The reclosers, **Figures 8**, **9**, and **10**, incorporate some breakers with vacuum extinguishing chambers (vacuum breaker), inside a polycarbonate shell for each pole, **Figures 11** and **12**. Each breaker, corresponding to each pole, is embedded in a polymer bush. This bush includes both current and voltage sensors. The breaker with contacts in vacuum is considered a nonmaintenance electrical switching apparatus. The drive mechanism has a high reliability and requires a revision at about 10 years or after 10,000 maneuvers.

one sensor per HV terminal, **Figures 11** and **12 (**Tavrida Electric recloser). Rogowski sensors are current sensors that produce a safe, low-voltage output [10]. The mechanism is operated by three separate magnetic actuators, one per pole, **Figure 11**. These magnetic actuators are mechanically interlocked to guarantee correct a three-phase operation. The device is latched into the closed position by magnetic latching. Each magnetic actuator utilizes a single coil which is used for both opening and reclosing operations [10] (Tavrida Electric recloser).

**Figure 10.** The REVAC recloser concept, up to 36 kV (RMS) rated maximum voltage and up to 630 A (RMS) rated

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continuous current [12] (courtesy of REVAC).

These recloser's devices can be successfully applied to the electric grids without isolated neutral. The conversion of the public grids to active (distribution/using) grids that use the high-tech smart devices like reclosers is expected to make in the future. Moreover, there is also considered

**Figure 11.** The Tavrida Electric recloser, the components of a pole (courtesy of Tavrida Electric) [10].

The implementation of the smart devices, as recloser type for automatic connecting/disconnecting decisions so that the branched or even looped operation could be possible by using the lines without any faults until the removal of the existing ones, allows auto-configuration of the smart microgrids.

Voltage sensing is carried out by conductive rubber screens that are capacitively coupled to the high-voltage (HV) terminals, and current sensing is performed by six Rogowski sensors,

**Figure 9.** The Thomas & Betts recloser concept, up to 38 kV (RMS) rated maximum voltage and up to 800 A (RMS) rated continuous current [11] (courtesy of Thomas & Betts).

**Figure 10.** The REVAC recloser concept, up to 36 kV (RMS) rated maximum voltage and up to 630 A (RMS) rated continuous current [12] (courtesy of REVAC).

closing cycles to eliminate transient faults and minimize network interruption. The reclosers, **Figures 8**, **9**, and **10**, incorporate some breakers with vacuum extinguishing chambers (vacuum breaker), inside a polycarbonate shell for each pole, **Figures 11** and **12**. Each breaker, corresponding to each pole, is embedded in a polymer bush. This bush includes both current and voltage sensors. The breaker with contacts in vacuum is considered a nonmaintenance electrical switching apparatus. The drive mechanism has a high reliability and requires a revi-

**Figure 8.** The Tavrida electric recloser concept, up to 40.5 kV (RMS) rated maximum voltage and up to 1250 A (RMS)

The implementation of the smart devices, as recloser type for automatic connecting/disconnecting decisions so that the branched or even looped operation could be possible by using the lines without any faults until the removal of the existing ones, allows auto-configuration

Voltage sensing is carried out by conductive rubber screens that are capacitively coupled to the high-voltage (HV) terminals, and current sensing is performed by six Rogowski sensors,

**Figure 9.** The Thomas & Betts recloser concept, up to 38 kV (RMS) rated maximum voltage and up to 800 A (RMS) rated

sion at about 10 years or after 10,000 maneuvers.

continuous current [11] (courtesy of Thomas & Betts).

rated continuous current [10] (courtesy of Tavrida electric).

of the smart microgrids.

92 Smart Microgrids

one sensor per HV terminal, **Figures 11** and **12 (**Tavrida Electric recloser). Rogowski sensors are current sensors that produce a safe, low-voltage output [10]. The mechanism is operated by three separate magnetic actuators, one per pole, **Figure 11**. These magnetic actuators are mechanically interlocked to guarantee correct a three-phase operation. The device is latched into the closed position by magnetic latching. Each magnetic actuator utilizes a single coil which is used for both opening and reclosing operations [10] (Tavrida Electric recloser).

These recloser's devices can be successfully applied to the electric grids without isolated neutral. The conversion of the public grids to active (distribution/using) grids that use the high-tech smart devices like reclosers is expected to make in the future. Moreover, there is also considered

**Figure 11.** The Tavrida Electric recloser, the components of a pole (courtesy of Tavrida Electric) [10].

**Figure 12.** The Tavrida Electric recloser, actuating the vacuum interrupter (courtesy of Tavrida Electric) [10].

grouping these within smart microgrids which have the autoconfiguration option [13]. Thus, the faults and contingencies will be limited or even removed, creating the frame for the supplied equipment (in a continuously increasing number due to the local and regional expansion) to operate until the removal of the fault. The characteristics of the analyzed public grids with isolated neutral regard their operation in general with a radial structure, **Figure 13**. Thereby, when a fault is produced, all the equipment is disconnected until the removal of the fault.

propagation. This is done by programming an opening/closing sequence, depending on the characteristics of the microgrid. For example, **Figure 15** is showing a possible process

**Figure 14.** Implementation of the recloser type devices for switching on the backup power supply. The case of two radial

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Reclosing interval can be defined: the open-circuit time between an automatic opening and the succeeding automatic reclosure [14]. Obviously, as reclosing interval increases, "risk of

Among the advantages of using these smart recloser devices, the following are mentioned:

**Figure 15.** Recloser operation mode, a possible process of programing reclosing.

of reclosing.

arc" reignition (RAR) will decrease.

structures of a public grid with isolated neutral.

In order to switch on the backup power supply, Substation 1 or Substation 2, respectively, **Figure 14**, is possible to the implementation of the recloser devices for autoconfiguration and automatic connecting/disconnecting decisions, in conjunction with a circuit breaker. And more important for this configuration is that this circuit breaker can also be assimilated with a smart recloser device, recloser 3, **Figure 14**.

These smart recloser devices can be used in order to monitor both the isolation resistance and other parameters of the considered microgrids. The actual implementation of the recloser devices for programming connecting/disconnecting process is also considered. Thus, the lines without any faults allow the continuity of power supply to consumers until the faults' removal. Furthermore, these electric grids, already active, are able to reconfigure based on the recloser devices to the initial operation mode, previous to the fault

**Figure 13.** Radial structure of a public grid with isolated neutral.

**Figure 14.** Implementation of the recloser type devices for switching on the backup power supply. The case of two radial structures of a public grid with isolated neutral.

grouping these within smart microgrids which have the autoconfiguration option [13]. Thus, the faults and contingencies will be limited or even removed, creating the frame for the supplied equipment (in a continuously increasing number due to the local and regional expansion) to operate until the removal of the fault. The characteristics of the analyzed public grids with isolated neutral regard their operation in general with a radial structure, **Figure 13**. Thereby, when a fault is produced, all the equipment is disconnected until the removal of the fault.

**Figure 12.** The Tavrida Electric recloser, actuating the vacuum interrupter (courtesy of Tavrida Electric) [10].

In order to switch on the backup power supply, Substation 1 or Substation 2, respectively, **Figure 14**, is possible to the implementation of the recloser devices for autoconfiguration and automatic connecting/disconnecting decisions, in conjunction with a circuit breaker. And more important for this configuration is that this circuit breaker can also be assimilated with

These smart recloser devices can be used in order to monitor both the isolation resistance and other parameters of the considered microgrids. The actual implementation of the recloser devices for programming connecting/disconnecting process is also considered. Thus, the lines without any faults allow the continuity of power supply to consumers until the faults' removal. Furthermore, these electric grids, already active, are able to reconfigure based on the recloser devices to the initial operation mode, previous to the fault

a smart recloser device, recloser 3, **Figure 14**.

94 Smart Microgrids

**Figure 13.** Radial structure of a public grid with isolated neutral.

propagation. This is done by programming an opening/closing sequence, depending on the characteristics of the microgrid. For example, **Figure 15** is showing a possible process of reclosing.

Reclosing interval can be defined: the open-circuit time between an automatic opening and the succeeding automatic reclosure [14]. Obviously, as reclosing interval increases, "risk of arc" reignition (RAR) will decrease.

Among the advantages of using these smart recloser devices, the following are mentioned:

**Figure 15.** Recloser operation mode, a possible process of programing reclosing.

• Increased economic efficiency: the unpredictable blackouts of electrical grids are removed, the maintenance time and costs are reduced, the weak points of the installations are quickly observed, and better organization of investment is possible.

**Author details**

Lucian Pîslaru-Dănescu<sup>1</sup>

Bucharest, Romania

Print ISSN: 1582-5175

IWCMC.2014.6906500

Catalogue. 2005

dx.doi.org/10.5772/intechopen.69603

Future Low Voltage Networks. July 31st 2014

2015;**6**(1):360-368. DOI: 10.1109/TSG.2014.2340446

α2 Simple Application Controllers. April 2005

Technical Catalogue Rev. 4. 1.2.2013, 2013

**References**

\* and Laurențiu Constantin Lipan2

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1 National Institute for Research and Development in Electrical Engineering ICPE-CA,

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[3] Boaski MAF, dos Santos C, Sperandio M, Bernardon DP, Ramos MJ, Porto DS. Coordination and selectivity of protection devices with reliability assessment in distribution systems. In: Volosencu C, editor. System Reliability; December 20 2017. ISBN 978-953-51-3706-1. Print ISBN 978-953-51-3705-4. DOI: 10.5772/intechopen.69603. http://

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[5] \*\*\* IEEE Guide for Safety in AC Substation Grounding, ANSI AEEC Std 80/86, New York

[6] Chousidis C, Nilavalan R, Lipan L. Expanding the use of CTS-to-self mechanism for reliable broadcasting on IEEE 802.11 networks. In: Proceedings of the IEEE International Conference on Wireless Communications and Mobile Computing Conference (IWCMC), 4-8 Aug, 2014. Nicosia, Cyprus: IEEE; 2014. pp. 1051-1056. DOI: 10.1109/

[7] Khan M, Ashton PM, Li M, Taylor GA, Pisica I, Liu J. Parallel detrended fluctuation analysis for fast event detection on massive PMU data. IEEE Transactions on Smart Grid.

[8] \*\*\*Mitsubishi Electric. Simple application controllers, Alpha & Alpha XL, Technical

[9] \*\*\*Mitsubishi Electric. Simple application controllers, Alpha XL, Programming Manual

[10] \*\*\*Tavrida Electric. Recloser based automation solutions for smart grid up to 40,5KV.

\*Address all correspondence to: lucian.pislaru@icpe-ca.ro

2 University Politehnica of Bucharest, Bucharest, Romania

[2] \*\*\*Mitsubishi Electric. FR-A540-22K. Technical Catalogue. 2005

