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Communication Signal for Rapid ShutdownSunSpec Interoperability Specification

Contributors:

XXX

AbstractThis document defines a multi-vendor, multi-device (e.g. inverter, module, string combiner, etc.) communication interoperability specification to support NEC 2014 and NEC 2017 and UL 1741 module-level rapid shutdown requirements. The intended audience for this document includes hardware and software designers and implementers of communication systems.

Communication Signal for Rapid Shutdown 1 www.sunspec.org

Prepared by the SunSpec Alliance

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Copyright © SunSpec Alliance 2009-20165. All Rights Reserved.

License Agreement and Copyright Notice

THIS DOCUMENT AND THE INFORMATION CONTAINED HEREIN IS PROVIDED ON AN "AS IS" BASIS AND THE SUNSPEC ALLIANCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY OWNERSHIP RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

THIS DOCUMENT MAY BE USED, COPIED, AND FURNISHED TO OTHERS, WITHOUT RESTRICTIONS OF ANY KIND, PROVIDED THAT THIS DOCUMENT ITSELF MAY NOT BE MODIFIED IN ANYWAY, EXCEPT AS NEEDED BY THE SUNSPEC TECHNICAL COMMITTEE AND AS GOVERNED BY THE SUNSPEC IPR POLICY. THE COMPLETE POLICY OF THE SUNSPEC ALLIANCE CAN BE FOUND AT WWW.SUNSPEC.ORG.


Natsuko Gillot, 11/18/15,

http://www.sunspec.org/

Revision History

Revision Date Reason1 09-02-2015 First Draft in SunSpec Template

2 09-09-2015 General requirements revised per discussion at 9/9/15 Work Group meeting.

3 10-7-2015 Section 3.1 Power Line Communication Requirements added,

4 10-15-2015 Changes added from 10/14/15 meeting

5 10-28-2015 Revision to Section 3.1.2, notes from 10/28/15 meeting

6 11-4-2015 Add Wireless Protocol

10 11-25-15Add all changes discussed at meetings through November 25. Add revised Wireless Section 6

11 12-16-15 Add revised Wireless Proposal.

12 1-18-16Changes defined frequencies, add Section 5.4.2 on Continuous Phase, make editorial changes throughout the document.

13 2-26-16Incorporates edited copy throughout document and removed the wireless section to a separate document.

14 3-2-16 Incorporates edits from March 2, 2016 meeting



17 4-11-16Incorporates edits from March 31, 2016 meeting and add Definition table and description of optional requirements.

18 ??5-18-16 ??Incorporated edits from May 18, 2016 meeting.

19 5-27-16Incorporates changes inferred from the output of the Amplitude/EMC subgroup chaired by Michael Viotto

20 6-1-2016 Updated table 4.4 to incorporate input.


About the SunSpec Alliance

The SunSpec Alliance is a trade alliance of developers, manufacturers, operators and service providers, together pursuing open information standards for the distributed energy industry. SunSpec standards address most operational aspects of PV, storage and other distributed energy power plants on the smart grid—including residential, commercial, and utility-scale systems— thus reducing cost, promoting innovation, and accelerating industry growth.

Over 70 organizations are members of the SunSpec Alliance, including global leaders from Asia, Europe, and North America. Membership is open to corporations, non-profits, and individuals. For more information about the SunSpec Alliance, or to download SunSpec specifications at no charge, please visit www.sunspec.org.

About the SunSpec Specification Process

SunSpec Alliance specifications are initiated by SunSpec members desiring to establish an industry standard for mutual benefit. Any SunSpec member can propose a technical work item. Given sufficient interest and time to participate, and barring any significant objections, a workgroup is formed. The workgroup meets regularly to advance the agenda of the team.

The output of the workgroup is generally in the form of an Interoperability Specification. These documents are considered to be normative, meaning that there is a matter of conformance required to support interoperability. The revision and associated process of managing these documents is tightly controlled. Other documents are informative, or make some recommendation with regard to best practices, but are not a matter of conformance. Informative documents can be revised more freely and frequently to improve the quality and quantity of information provided.

SunSpec Interoperability Specifications follow this lifecycle pattern of DRAFT, TEST, APPROVED and SUPERSEDED.

For more information or to download a SunSpec Alliance specification, go to http://www.sunspec.org/specifications.


http://www.sunspec.org/

Table of Contents1 Overview .......................................................................................................................................... 8

2 Specification Objectives .............................................................................................................. 8

3 General Requirements ................................................................................................................. 9

3.1 System Configuration .......................................................................................................................... 9

3.1.1 Initiator ................................................................................................................................................................. 9

3.1.2 Master .................................................................................................................................................................... 9

3.1.3 Slave .....................................................................................................................................................................10

3.1.4 Master/Slave Interactions .........................................................................................................................10

3.2 Operational Considerations ........................................................................................................... 10

3.3 Safety Considerations ....................................................................................................................... 10

4 Modes of Operation .................................................................................................................... 11

4.1 Active Mode .......................................................................................................................................... 11

4.2 Shutdown Mode .................................................................................................................................. 11

4.2.1 Reduced power consumption during the night ................................................................................11

4.2.2 Ease of installation ........................................................................................................................................11

4.2.3 Supply of electronics ....................................................................................................................................11

4.3 Mode Transitions ............................................................................................................................... 12

4.4 Mode Specification Table .................................................................................................................13

5 Power Line Communication (PLC) Requirements ...........................................................13

5.1 Master Transmitter Requirements ..............................................................................................13

5.1.2 Transmitter Out-of-Band Emission Requirements .........................................................................14

5.1.3 Transmitter In-Band Emission Requirements ..................................................................................15

5.2 Slave Receiver Specifications ......................................................................................................... 16

5.2.2 Receiver Out-of-Band Rejection Specifications ................................................................................17

5.2.29 Receiver In-Band Rejection Specifications ......................................................................................18

5.3 PLC Specification Table .................................................................................................................... 19

6 Test Specification ........................................................................................................................ 20

6.1 Protocol Information Conformance Statement ........................................................................20

6.2 Communication System Test Plan ................................................................................................20

6.2.1 Objective ............................................................................................................................................................20

6.2.2 Test Administrator ........................................................................................................................................20


6.2.3 Test Scope ......................................................................................................................................................... 20

6.2.4 Procedure ..........................................................................................................................................................20

6.2.5 Certification ......................................................................................................................................................20

6.3 PLC Test Plan ....................................................................................................................................... 20

6.3.1 Objectives ..........................................................................................................................................................20


6.3.3 Test Scope ......................................................................................................................................................... 20

6.3.4 Procedure ..........................................................................................................................................................20

6.3.5 Certification ......................................................................................................................................................20

6.4 Wireless Test Plan ............................................................................................................................. 20

6.4.1 Objectives ..........................................................................................................................................................20


6.4.3 Test Scope ......................................................................................................................................................... 20

6.4.4 Procedure ..........................................................................................................................................................20

6.4.5 Certification ......................................................................................................................................................21

7 Appendix A: References ............................................................................................................ 21

8 Appendix B: Selection of PLC carrier frequency ...............................................................21

9 Appendix C – Spread frequency shift keying (S-FSK) principle ...................................22

10 Appendix D: Additional Informative Information .........................................................23

2 Overview .......................................................................................................................................... 9

3 Specification Objectives .............................................................................................................. 9

4 General Requirements .............................................................................................................. 10

4.1 System Configuration ........................................................................................................................10

4.1.1 Initiator .............................................................................................................................................................. 10

4.1.2 Master ................................................................................................................................................................. 10

4.1.3 Slave .....................................................................................................................................................................11

4.1.4 Master/Slave Interactions .........................................................................................................................11

4.2 Operational Considerations ........................................................................................................... 11

4.3 Safety Considerations ....................................................................................................................... 11

5 Modes of Operation .................................................................................................................... 12

5.1 Active Mode .......................................................................................................................................... 12

5.2 Shutdown Mode .................................................................................................................................. 12

5.2.1 Reduced power consumption during the night ................................................................................12

5.2.2 Ease of installation ........................................................................................................................................12


5.2.3 Supply of electronics ....................................................................................................................................12

5.3 Mode Transitions ............................................................................................................................... 13

5.4 Mode Specification Table .................................................................................................................14

6 Power Line Communication (PLC) Requirements ...........................................................14

6.1 Master Transmitter Requirements ..............................................................................................14

6.1.2 Transmitter Out-of-Band Emission Requirements .........................................................................15

6.1.3 Transmitter In-Band Emission Requirements ..................................................................................15

6.2 Slave Receiver Specifications ......................................................................................................... 16

6.2.2 Receiver Out-of-Band Rejection Specifications ................................................................................17

6.2.3 Receiver In-Band Rejection Specifications .........................................................................................17

6.3 PLC Specification Table .................................................................................................................... 18

7 Test Specification ........................................................................................................................ 19

7.1 Protocol Information Conformance Statement ........................................................................19

7.2 Communication System Test Plan ................................................................................................19

7.2.1 Objective ............................................................................................................................................................19


7.2.3 Test Scope ......................................................................................................................................................... 19

7.2.4 Procedure ..........................................................................................................................................................19

7.2.5 Certification ......................................................................................................................................................19

7.3 PLC Test Plan ....................................................................................................................................... 19

7.3.1 Objectives ..........................................................................................................................................................19


7.3.3 Test Scope ......................................................................................................................................................... 19

7.3.4 Procedure ..........................................................................................................................................................19

7.3.5 Certification ......................................................................................................................................................19

7.4 Wireless Test Plan ............................................................................................................................. 19

7.4.1 Objectives ..........................................................................................................................................................19


7.4.3 Test Scope ......................................................................................................................................................... 19

7.4.4 Procedure ..........................................................................................................................................................19

7.4.5 Certification ......................................................................................................................................................20

8 Appendix A: References ............................................................................................................ 20

9 Appendix B: Selection of PLC carrier frequency ...............................................................20

10 Appendix C – Spread frequency shift keying (S-FSK) principle .................................21


11 Appendix D: Additional Informative Information .........................................................22


Table of Figures Figure 1..........................................................................................................................................16

Figure 2..........................................................................................................................................17

Figure 3..........................................................................................................................................18

Figure 4..........................................................................................................................................19

Figure 5 Selection of PLC carrier frequency.................................................................................22

Figure 6 FSK on Frequency Domain.............................................................................................23


Nomenclature

Abbreviation Meaning

Definitions (not sure if ok to use definitions from other sources)

Term MeaningComponents Equipment intended to be used in a PV Rapid Shutdown

System to initiate, disconnect, isolate or attenuate the controlled conductors of a PV system. (UL 1741, Section 2.49D). UL 1741 refers to components as PV Rapid Shutdown Equipment (PVRSE).

Communication Protocols Formal descriptions of digital message formats and rules. (Techopedia)

Initiation Device A manual or automatic switching device, input port or signal that will result in the activation of the rapid shutdown system function(s). An initiation device is intended to meet the function of the initiation methods mentioned in Section 690.12 of the National Electrical Code (UL 1741, Section 2.49B). The Initiation Device is the same as the Initiator.

Master The equipment that is responsible for transmitting a communication signal that reflects the current state of the Initiation Device. (from Section 3.1.2)

PV Power Source A dc array or aggregate of arrays that generates dc power. (from NEC, Section 690.2)

Slave The equipment that is responsible for receiving the communication signal transmitted by a Master and is capable of initiating a state change of PV power source components based on the signal received. (from Section 3.1.3)

System System made up of components intended to disconnect, isolate or attenuate the controlled conductors of a PV system. (revised from UL 1741, Section 2.49E)


Larry Sherwood, 05/18/16,

Not sure if need with a generic definition.

1 OverviewThe 2014 National Electrical Code (NEC) includes a requirement for rapid shutdown of controlled conductors outside the array boundary. As of August 2015, this version of the NEC is in effect in 23 states.

The 2017 National Electrical Code (NEC) is likely to include a requirement for module level shutdown. This section of the NEC will likely become effective January 1, 2019 rather than January 1, 2017 for the rest of the code. States and local jurisdictions adopt the new editions of the NEC at different times.

Both the 2014 and 2017 Rapid Shutdown requirements only apply to PV systems installed on buildings (i.e. they do not apply to ground-mount systems).

California will likely adopt the 2017 NEC in 2020. Based on past history, the following states are likely to adopt the 2017 NEC in 2017: Alabama, Arkansas, Colorado, Idaho, Kentucky, Maine, Massachusetts, Minnesota, Montana, Nebraska, New Mexico, North Dakota, Oregon, Rhode Island, South Dakota, Texas, Vermont, Washington, and Wyoming.

UL 1741 is currently being revised to add requirements for PV Rapid Shutdown Equipment (PVRSE) and PV Rapid Shutdown Systems (PVRSS). The current revision to the UL 1741 standard creates requirements for PVRSE and PVRSS designed to meet the 2014 NEC. A future revision will revise the requirements for PVRSE and PVRSS to meeting the 2017 NEC.

To meet the requirements of the 2017 NEC and UL 1741, modules, inverters, charge controllers, and other equipment may need to communicate with each other. Different manufacturers could develop different communication protocols to accomplish the rapid shutdown system functionality. Proprietary solutions would make support of multi-vendor solutions more complex and costly.

It is desirable to have a single communication specification that would provide interoperability between the different components from different manufacturers that are required to participate in the rapid shutdown system.

It is possible to achieve NEC compliance without a communication signal. This specification does not apply in that case.

2 Specification ObjectivesThe objectives of this specification are to:

Identify the communication requirements specified or implied by NEC 2014, NEC 2017 and UL 1741 that pertain to module-level rapid shutdown.

Describe a communication framework that is open, flexible, scalable, and available royalty-free to manufacturers of power electronics, PV modules, inverters, and PV balance-of-system components.

Define parameters and operating ranges associated with aspects of communication systems that support module-level rapid shutdown such that disparate components can be


evaluated for conformance to this specification and multi-vendor interoperability can be established.

As such, this specification represents an important addition to the library of SunSpec interoperability specifications that are offered at no cost to the Distributed Energy industry.

3 General RequirementsThis SunSpec Communication Signal for Rapid Shutdown Specification defines how to propagate the shutdown state of a PV system to the individual power production components.

These general requirements apply to any PV system components and communication networks supporting the rapid shutdown system communication capabilities defined in relevant NEC and UL standards. General requirements are divided into categories: system configuration, application protocol, operational, and safety requirements.

If a component and communication network meets the optional requirement in Section 4.2.3.4 of this specification, then the components can be designated as meeting the option requirement.

This document describes requirements and constraints associated with powerline communication networks that are used to support this application.

3.1 System ConfigurationA rapid shutdown communication System is a collection of Components and Communication Protocols that are used to implement rapid shutdown requirements as defined by NEC 2014 or NEC 2017. Components of a rapid shutdown communication System are Initiator(s), Master(s), and Slave(s).

Communication Signal for Rapid Shutdown is designed to support rapid shutdown requirements of any PV system governed by NEC 2014, NEC 2017, or applicable UL standard(s), irrespective of system configuration or physical network choice. Issues that commonly effect application protocol performance—including cross-talk from other protocols, noise, and line impedance—must be accounted for.

Insert Figure depicting a rapid shutdown communication System.

3.1.1 InitiatorAn Initiator is the equipment that is responsible for initiating the rapid shutdown mechanism in the System.

The term Initiator, in this context, is defined in the 2017 NEC.

3.1.1.1 Requirement: A System must have one or more Initiators.

3.1.2 MasterA Master is the equipment that is responsible for transmitting a communication signal that reflects the current state of the Initiation Device. The portion of the PV system controlled by a


single Master is referred to as a Subsystem. The minimum and maximum Subsystem supported by a single Master is manufacturer dependent and must be specified.

3.1.2.1 Requirement: A System must have at least one Master.

3.1.2.2 Requirement: A Subsystem must have only one Master.

[3.1.2.3] Requirement: A Master must specify the min / max number of PV strings and min / max DC power rating for the Subsystem to ensure the transmission signal arrives across the entire Subsystem with adequate strength per receive power specifications.comply with the minimum output voltage and minimum output source impedance specified in Section 5.3

3.1.3 SlaveA Slave is the equipment that is responsible for receiving the communication signal transmitted by a Master and is capable of initiating a state change of PV power source components based on the signal received.

3.1.3.1 Requirement: A Subsystem must have at least one Slave.

3.1.4 Master/Slave InteractionsMaster/slave interactions are at the heart of Communication Signal for Rapid Shutdown operation. By optimizing for efficiency and simplicity, low-cost and reliable system solutions are possible.

3.1.4.1 Requirement: Master must transmit a permission to operate signal to slaves when the Initiator indicates rapid shutdown is not active.

3.1.4.2 Requirement: Master must stop transmitting a permission to operate signal to slaves when the Initiator indicates rapid shutdown is active.

3.1.4.3 Requirement: Slave must be able to receive a permission to operate signal and initiate the ability for the associated power-producing equipment to produce power.

3.1.4.4 Requirement: Slave must detect the absence of a permission to operate signal and initiate the shutdown of power production by associated power producing equipment.

3.2 Operational ConsiderationsOperational simplicity is a key goal of the Communication Signal for Rapid Shutdown. Features that open the possibility to unwanted truck rolls or other unnecessary human interaction are to be avoided if at all possible

3.2.1.1 Requirement: Must provide a mechanism to bring PV system(s) back online after a rapid shutdown event.

Local regulations may add requirements for start-up activation.



Need to revise this requirement based on Subgroup work. Focus on the strength of the signal.

3.3 Safety ConsiderationsMandatory features of the Communication Signal for Rapid Shutdown specification represent minimum functionality required to achieve NEC 2014 or NEC 2017 safety standards.

3.3.1.1 Requirement: Communication Signal for Rapid Shutdown must support shut down in a manner that meets the function safety requirements of UL 1741.

3.3.1.2 Requirement: System must energize only when Initiator mechanism is set to “ready to operate” position.

3.3.1.3 Requirement: Must conform to applicable UL standard(s).

4 Modes of OperationTwo modes of operation are defined for a System: Active Mode and Shutdown Mode. Active Mode is characterized by the typical state of a PV system, generating power unimpeded by the Rapid Shutdown System. For this condition to persist, the Initiator must be set to the “on” state. If the Initiator is set to “off” state, the respective Master (including all Subsystems) must enter the Shutdown Mode. Transitioning from Active Mode to Shutdown Mode must comply with overall timing constraints as set forth in NEC 2017. There are no timing constraints when transitioning from Shutdown Mode to Active Mode.

4.1 Active ModeNo specifications or restrictions are placed on PV generators during the Active (power producing) Mode. The Rapid Shutdown System must continuously monitor the Initiator for a change in allowable operating state.

4.2 Shutdown ModeNEC 2017 specifications require the illuminated PV generators and complete PV system to be de-energized to a maximum as required in 2017 NEC and as specified in Section XXX (of this Specification) when in the Shutdown Mode. Instead of completely zeroing output power capability, it is desirable to provide a non-zero output within the range offered as allowable by NEC 2017.

When in shutdown mode, the slave(s) providing a low voltage, low current standby signal offer the following advantages:

4.2.1 Reduced power consumption during the nightThe presence of the standby signal of the slaves indicates the presence of daylight. It allows to turn-off the keep alive signal of the master overnight and reduces thereby the power consumption of the system.

4.2.2 Ease of installationThe installer can verify the correct polarity, the count of modules per string, the string associated wires etc. without a special tool to inject the keep alive signal. He has the additional benefit of working on safe voltage levels and a limited power now.



Insert Section reference.

4.2.3 Supply of electronicsWhen in shutdown mode, it is possible for the slaves, instead of providing a standby signal only, to provide enough standby power to supply the keep alive circuitry (e.g. the master or signal generator and a circuit who measures and signals the Shutdown operation) from the illuminated PV generator. This prevents a deadlock with purely PV powered systems. With this feature no AC supply is needed to power up the system

4.2.3.1 Requirement: The output power capability of PV system in Shutdown Mode must stay below the maximum voltage specifications stated per NEC 2017.

4.2.3.2 Requirement: The minimum current available in the shutdown state must be sufficient to guarantee operation of equipment monitoring the state of the modules. In the case of field installation measurements, a typical low-impedance type multi-meter can have a 10kΩ input impedance so the current capability of the constant output voltage must be at least 0.1mA.

4.2.3.3 Requirement: : Each PV generator must provide constant output voltage VOFF, with current compliance IOFF,MAX, when in the Shutdown state.

4.2.3.4 Optional Requirement (Standby Power): Each PV generator must provide constant output voltage VOFF, with current compliance IOFFHI,MAX , when in the Shutdown state.

In the case, where offering power to the master is desirable, higher current capability is required.

4.3 Mode TransitionsNEC 2017 regulations allow for 30 seconds from the initiation event until the system must be fully settled in the de-energized Shutdown mode. In order to facilitate interoperability, it is important that the total time to de-energize is equitably allocated to the constituent steps of the de-energization process.

A typical de-energization process (mode transition) can be considered as the following sequence of events.

T1: Initiator signals Shutdown state to Master

T2: Master ceases to send KeepAlive Communications Signal to Slaves

T3: Slaves de-energize all PV Power Sources

T4: Inverter stored charge is eliminated

There are no timing requirements placed on the system with respect to a mode transition from Shutdown to Active Modes.



Edit


Edit

4.4 Mode Specification Table Symbol Mode Specification Min. Nom. Max. Unit Remark

VOFF PV Power Source voltage in Shutdown TBD0.65 TBD TB

D1.0 V

Accommodates % or fixed methodsTolerance spec includes accuracy and impedance

IOFFOutput current for Voff tolerance window Max current atwhich output drops 0.1V 0.0101 NA mA

IOFFPWRMaximum output current in standby power mode

IOFF,MAXMaximum output current in standby signal mode 0.1 0.5 1 mA

IOFFHI,MAXOutput current for Voff tolerance window for high power option

TBD400 TBD

NATB

DmA

1. Need informative note to describe where this can/should be used.2. Need second note describing total current in array should not exceed 8 amps. M. Viotto to propose language.

NSTRING TBD 10Max Parallel Strings for High Power Shutdown Systems

FC Suggested Crystal FrequencyTB

D16MHz

This is an informative note. Please move to informative section.

T1 Time for Initiator to relay to Master NA TBD 2 sAdd note about total time limit of 30 seconds.

T2 Time for Master to stop KeepAlive NA TBD 2 s

T3 Time for Slave to de-energize PV Power Sources NA TBD 13 s

T4 Time for Inverter stored charge to be eliminated NA TBD 13 s

5 Power Line Communication (PLC) RequirementsA Master communicates with all Slaves in the Subsystem over Power Line Communications. The Master continuously transmits a “Keep Alive” bit sequence to indicate PV Power Sources have permission to operate in the Active Mode. If the Master ceases to transmit the Keep Alive sequence then the Subsystem enters the Shutdown Mode. Three other bit sequences are defined and reserved for future use.

5.1 Master Transmitter Requirements



Remember 2014 NEC requirement when define these values.


Seth Kahn to make recommendation on different option.


Seth Kahn to make recommendation on different option.

The Master broadcasts a Keep Alive signal using a spread frequency shift keying (S-FSK) transmitter. The transmitter must provide the receivers with signals at satisfactory level for demodulation. It must develop sufficient power on a given load impedance and must have a well-defined output impedance.

[5.1.1.1] Requirement: Transmitter must send a ‘permission to operate’ signal when an Initiator indicates rapid shutdown is not active, corresponding to one of fourthe code words defined as W1, W2, W3, W4. Code words are transmitted continuously in a repetitive cyclical fashion with no headers or time spacing in-between.

[5.1.1.2] Requirement: Transmitter must have ZOUT an output impedance in the range specified for ZOUT in the transmission frequency band FM to FS.

[5.1.1.3] Requirement: Transmitter must provide and PTX open circuit output power voltage in the range specified for VTX on 50 ohm load.

5.1.1.1[5.1.1.4] Requirement: The Master must transmit Keep Alive signal using a mark and space tone frequency of FM and FS respectively.

5.1.1.2[5.1.1.5] Requirement: The Master must maintain the transmission of a mark or a space tone for TS duration, resulting in an effective bit rate of RS.

5.1.1.3[5.1.1.6] Requirement: The Master must maintain phase coherency when transitioning between mark and space tones

5.1.2 Transmitter Out-of-Band Emission RequirementsThe transmitter must not generate spurious out-of-band signals that could interfere with other communication systems or with PV system components like MPP tracker or AFCI

5.1.2.1 Requirement: the Out-of-Band spurious frequency components must not exceed the levels defined in Table 1 and depicted in Figure 1.

Out-of-Band Spectral Mask

F [kHz] 0 20072 20072FM –

11.2550FM –

2011.25FS +

2011.25FS +

5011.25 1000P [dBm] -40 -40 -20 -20 20 20 -20 -20

Table 1



Subgroup

Figure 1

5.1.3 Transmitter In-Band Emission RequirementsTo ensure easy separation of the carriers in the demodulator, the in-band spectrum of the two FSK carriers must be limited.


5.1.3.1 Requirement: the In-Band frequency components must not exceed the levels defined in Table 2 and depicted in Figure 2.

The frequency and amplitude values are relative to the actual frequency and power of each of the two FSK carriers.

In-Band Spectral MaskF-Fc [kHz] -50 -9 -9 -5 -5 5 5 9 9 50P [dBc] -30 -30 -20 -20 0 0 -20 -20 -30 -30

Table 2

Figure 2

5.2 Slave Receiver SpecificationsThe receiver must be able to handle a large range of input signal amplitude. Maximum amplitude is received with maximum TX power and minimum PV string attenuation, and conversely, minimum signal is received with minimum TX power and maximum PV string attenuation.


5.2.1.1 Requirement: Receiver must decode the FSK signals at FM and FS as sent by the transmitter.

[5.2.1.2] Requirement: Receiver must decode indicate the presence of KeepAlive signals without gaps or interruptions over at least a 1 hourwith a probability of at least 99% observation period in the presence of an uninterrupted SunSpec-compliant FSK signal having an amplitudes in the range VIRXSENSE mVA – VIRXMAX mV r.m.sA.

[5.2.1.3] Requirement: Receiver must have pass-through impedance with absolute value less thanin the range specified for ZRXS and ZRXM at FSM and FMS frequencies respectively.

[5.2.1.4] Requirement: Receiver shallmust indicate the absence of KeepAlive signals without any false alarms over at least a 1 hour observation period in the presence of a standardized noise and interference test signal as specified have a false-detection probability of less than PFALSE as demonstrated in conditions set forth in the SunSpec Rapid Shutdown Compatibility Test Plan.

The receiver must not attenuate excessively the FSK signal, i.e. it must have limited input impedance in the PLC band.

5.2.2 Receiver Out-of-Band Rejection Specifications

The receiver must not be perturbed by signals outside the receive band.

5.2.2.1 Requirement: Receiver must tolerate the presence of out-of-band signals having rejection ratio values as defined in Table 3 and depicted in Figure 3, for a sensitivity reduction of no more than 3dB.

5.2.3 5.2.4

0

5.2.53

5.2.63

5.2.77

5.2.87

5.2.91

5.2.101

5.2.111

5.2.121

200

5.2.132

5.2.143

5.2.153

5.2.161

5.2.17

5.2.18-

5.2.19-

5.2.20-

-40

5.2.21-

5.2.22- 5.2.23

0 0

5.2.24-

5.2.25-

5.2.26-

-30

5.2.27-

5.2.28-

Table 3


Charles Razzell, 05/27/16,

Redundant with requirement 5.2.1.3


Is 99% too low?

Figure 3

5.2.29[5.2.3] Receiver In-Band Rejection Specifications

The receiver must be able to separate the two carrier frequencies of the FSK modulated RF signal.

5.2.29.1[5.2.3.1] Requirement: Receiver must reject in-band signals by values defined in Table 3 and depicted in Figure 4.

Rx In-Band Rejection


F-Fc [kHz] -50 -9 -9 -3 -3 3 3 9 9 50RR [dB] -30 -30 -20 -20 0 0 -20 -20 -30 -30

Table 4

Figure 4

5.3 PLC Specification TableSymbol Master Specification Min. Nom. Max. Unit Remark

W1 Code Word 1 100010011010111 Keep AliveW2 Code Word 2 001111110111010 ReservedW3 Code Word 3 111001000001100 ReservedW4 Code Word 4 010100101100001 Reserved

FM Mark Frequency 468.75131.25 kHz 6.25kHz × 21

FS Space Frequency 143.75481.25 kHz 6.25kHz × 23

TS Bit Period 5.12 msRS Bit Rate 195.3125 HzZTX Transmitter Output Impedance 402 50 605 Ω

PTXVTX

Transmitter Power into 50ΩOutput Voltage into >100 kΩ

190.75 201.0 231.25 dBmV r.m.s. (100mW)

IRXMAXVRX

MAX

Receiver Input Current Voltage Max 250 +36

mdBmAV

r.m.s.

VTX/4 (potential difference developed across ZRX63 mA @99% success rate)

IRXSENSEVR

XSENSE

Receiver Input Current Voltage Minimum Sensitivity -10 10

mdBmAV

r.m.s.

VTX/100 (potential difference developed across ZRX)0.31mA @99% success rate

ZRXSReceiver Output Line Impedance @ FS

5 50 Ω



Discuss after receive subcommittee report

ZRXM Receiver Line Impedance @ FM 5 50 ΩPFALSE Probability of false detection Per SunSpec testing

6 Test Specification6.1 Protocol Information Conformance Statement6.2 Communication System Test Plan6.2.1 Objective

6.2.2 Test Administrator

6.2.3 Test Scope

6.2.4 ProcedureEntry criteria

Step-by-step plan

Exit criteria

6.2.5 Certification

6.3 PLC Test Plan6.3.1 Objectives


6.3.3 Test Scope


Step-by-step plan

Exit criteria

6.3.5 Certification

6.4 Wireless Test Plan


6.4.1 Objectives


6.4.3 Test Scope


Step-by-step plan

Exit criteria

6.4.5 Certification

7 Appendix A: References2014 National Electrical Code, National Fire Protection Association (section 690.12 includes Rapid Shutdown requirements)

2017 National Electrical Code, National Fire Protection Association (will be adopted in summer 2016) (section 690.12 includes Rapid Shutdown requirements)

UL 1741, draft sections on Rapid Shutdown Equipment and Rapid Shutdown Systems

8 Appendix B: Selection of PLC carrier frequencyThe carrier frequency range is chosen in consideration of the specific circumstances of a PV-system. The following points justify the choice of this range:

• Frequency range of available arc fault detection units

Arc faults generate typical signatures in AC and DC. The AC signature is a pink noise influenced by the impedance of the PV-generator. The amplitude rises with an increase in frequency. Up-to-date available arc fault detection units analyze frequencies between 1kHz and up to 450 kHz. Sending a keep alive signal within the detection range can cause false tripping and will reduce the sensitivity of detecting real arcs.

• Inverter noise

Inverter noise is a mix of common mode and differential mode noise. The switching frequency and the harmonics are typically in the range of 5 kHz to 200 kHz. The amplitude decreases with an increase in frequency. The inverter noise influences the reception and detection of the keep alive signal at these frequencies in a negative way because it reduces the signal to noise ratio.

• Injected noise or radio signals

Above approximately 550 kHz the sensitivity of a PV-generator for injected noise rises with an increase in frequency. Examples for such noise sources are switching power supplies, radio stations, electric motors, welding equipment and, gas discharge lamps, etc.) This noise influences


the detection of the keep alive signal at these frequencies negatively because of damping the signal to noise ratio.

• Crosstalk

Above approximately 550 kHz the parasitical line elements dominate. With increase in frequency the keep alive signal can also be seen at a nearby cable. A crosstalk of the keep alive signal can unintentionally activate a close-by PV-generator.

• Line attenuation

Above approximately 300 kHz the parasitical line elements begin to dominate. They form resonant points and cause bypass paths for frequencies at this points. Also the inductance of the wires comes more and more into effect. The line attenuation damps the keep alive signal at high frequencies and reduces the signal to noise ratio.

The Figure below visualizes the combination of these effects:

Figure 5 Selection of PLC carrier frequency

The overlap and combination of the effects described above form a frequency gap between 450 kHz and 500 kHz – the ideal frequency range for the carrier frequency of the keep alive signal.

9 Appendix C – Spread frequency shift keying (S-FSK) principle

S-FSK is a modulation and demodulation technique combining some of the advantages of a classical spread spectrum system, i. e., immunity against narrowband interferences with the advantages of a classical FSK system, low-complexity, and well-investigated implementations.


The transmitter assigns the space frequency f_S to “data 0” and the mark frequency f_M to “data 1”. The difference between S-FSK and the classical FSK lies in the fact that f_S and f_M are placed far from each other (spreading). By placing f_S far from f_M, their transmission quality becomes independent, i.e., each frequency will have its have its own attenuation factor and local narrow-band noise spectrum.

The receiver performs conventional FSK demodulation at the two possible frequencies (the half-channels) resulting in two demodulated signals d_S and d_M. If the average reception quality of the two half-channels is similar, then the decision unit decides on the higher of the two demodulated channels (“data 0” if d_S>d_M, “data 1” if d_S<d_M). If, however, the average reception quality of one half-channel is significantly better than the quality of the other half-channel, then the decision unit compares the demodulated signal of the better channel with a threshold T, thus ignoring the worse channel.

Figure 6 FSK on Frequency Domain

10Appendix D: Additional Informative InformationWith typical system designs and module characteristics there will be less than 30 modules connected in series. Therefore, an output voltage of VOFF in the sub-volt range will satisfy the NEC requirement of a maximum of 30 Volts after a rapid shutdown initiation.

The Master suggested crystal frequency is 16 MHz in order to synthesize specified tone frequencies


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