Upload
violator
View
218
Download
0
Embed Size (px)
Citation preview
8/3/2019 nps4AD3
http://slidepdf.com/reader/full/nps4ad3 1/5
Development of Digital Protective Relay Tester under IEC61850CHEN Hui,CHEN Jiong-cong,LIANG Xiao-bing,YU Nan-hua
Electric Power Research Institute of Guangdong Power Grid Corporation,
Guangzhou 510080,P.R. China
E-MAIL:[email protected]
Abstract:The novel tester of digital protective relay based on
IEC61850 is proposed in this paper. The tester’s system
architecture is based on multi-CPU(CPU+DSP) high speed
hardware platform and real time operation system, it can
receive and sample the analog test data on time, which is then
converted into digital test data according to IEC61850 protocol.This tester also has the GOOSE trip signal which receive, the
analysis digital protection device sends out,and the circuit
breaker position contact signal encoding, the group frame,
transmits GOOSE the switch status to give the digitized relay
protection installment and so on. The transient simulation
testing platform is established, which can construct the electric
quantity of each test cycle in the period of protection’s operation
for sending under IEC61850. Due to the special recursive
algorithm and detecting the action of protection,the tester can
complete the closed loop experiment of tripping-reclose-tripping
forever. With the help of man machine interface, it ’s very
convenient to performance dynamic simulation test、 static
simulation test and transient simulation test. This tester also get
the fine results in the check of transient simulation test.
Keywords: IEC61850; digital protection ; digital relay
protection tester;closed loop experiment;real time operation
system
0. Introduction
In recent years, with the rapid development of integratedsubstation automation technology and communication technology,all kinds of unconventional optic-electronic measurement system
gradually replaced electromagnetic mutual-inductance measurementsystems. As the release of IEC61850 substation automation
communication protocol, the realizing digitization in substationhas become the future direction of substation automation technology
development[1]~[4].The use of digital protection will inevitable bring changes in
corresponding test, testing equipment and testing methods. After adopting new digital protection devices, because of getting
information and transmitting control commands in accord with the
transmission IEC61850 statute of communication network, it’sdifferent from traditional relay protection in test methods [5]~[8]. Inorder to ensure the safe and stable operation of digital substation, we
need to research on test methods, means and standard, on this basis,and develop new protective relay tester.
In the IEC61850 framework, the optic-electronic transformer
of process level will transmit digital sample value which is
converted internal by the optical fiber transmission to merge unit
(MU), the merge unit do synchronous processing after the secondaryside data collection from each optic-electronic transformer, group
frame according to IEC61850-9, and transmit to new digital protective relay device through the optical fiber [9]~[11].
This tester will simulate all the operation from optic-electronic
transformer to merge unit and from relay protection to intelligentswitch, it includes the functions and characters as follows:1.It canreceive multichannel analog signals(voltage and current), and group
frame one by one according to IEC61850-9 which is transmitted to
relay protection internal in real time[12]~[13].2.It has several digitalinput port and digital output port, the action signal from relay protection is transmitted to this tester in the form of GOOSE signal
or digital output, then the tester transmits the signal to switch devicein dynamic simulation laboratory or digital input in protection tester by its own digital output.3.With the internal simulation test platform,
it can finish the closed loop experiment according to the chosen
simulation fault module or fault situation[14]. This test system is baseon the existing power system dynamic simulation experiment whichconsists of mature and widely used technology, relay protection
static test and electro-magnetic transient simulation test, it makestraditional test methods play an important role in the new digital protection test, experiments and simulation analysis experiments.
1. Hardware design
This tester ’s global design of hardware framework is shown infigure 1-1.
dual-
port
RAM
DSP
Management
CPU
AD
sampling
module
Optical
fiber interface 1
Optical
fiber
interface 2
GPS
module
Optic-electronic
isola
tion
8 pairs
of digitalinput
terminal
Optic-electronic
isolation
8 pairs
of digital
output
terminal
Human-
machine
interface
Current and
voltage
converter
Dynamic
simulation
experiment
transformer
interface
Protection device
samples valuesinput interface
Protection device
GOOSE information
output interface
External
switch
interface
Protection
device trip
junction
Fig.1-1 The structure of tester hardware
8/3/2019 nps4AD3
http://slidepdf.com/reader/full/nps4ad3 2/5
1.1 Processor
Due to the high requirement of test system for real-time data
processing, in order to realize the function of many complex tasks
for a test device, the selection of the core processor hardware iscrucial. This tester chooses the real-time system with combinationof low-power CPU and DSP, CPU is mainly responsible for the
management, man-machine interface and communication with
DSP,and DSP has the strong data processing ability and high speed,
which is mainly responsible for data acquisition, encoding frame,
sending and receiving GOOSE signals and communication with
CPU. The data communication between CPU and DSP is mainlyfinished through dual-port RAM on DSP.
1.2 A/D sampling and control
Considering the need of common unilateral and bilateral line protection, and double ring, three ring transformer protection test,it’s composed of 27 analog channels. This tester has to transmit the
input analog signals to conventional small electrical signals through
internal current and voltage convertor, then the signals go into 16 bitA/D sampling module which is controlled by FPGA on DSP board.
1.3 Digital input and digital output
Some digital protection trip signals are still generated by
traditional hard trip logic circuit, in order to detect open and closedhard junction state in the test procedure, 8 digital input channels areestablished, and every channel has corresponding anti-jammingmeasures.
According to IEC61850 protocol, the protection sends open
and closed digital signals to on-site intelligent switch to control the breaker by Ethernet network, so this digital protective relay tester must imitate some intelligent switch functions, namely, it will outputhard logic junction, and trip simulation test device or dynamic
simulation test system switches when it receives trip data frames,
this tester establishes 8 digital output channels in all.
1.4 Network communication
This digital protective relay tester is mainly communicatedwith protection by Ethernet network, which includes samplingtransmitting signals from tester to protection and logic signals from
protection to tester, such as tripping breaker signals, blockingsignals and warning signals.
2 Design thinking
This digital protective relay tester mainly consists of twoimportant functions: analog experiment and simulation experiment,it also includes management and analysis modules of experiment
data. There functions depend on the realization of IEC61850
protocol in sampling value transmission model and GOOSEinformation model transmission. According to the demand function,this tester is determined specific software and hardwareconfigurations after its function division. The management CPU
runs on the Windows2000 operation system which is famous with
stability, using Microsoft Visual c + + development environment,the human-machine interface management software is developedwhich embeds simulation experiment function and communicationfunction with DSP, and realizes data management and analysis in the
experiment or after the experiment. The DSP runs on the small
famous real time operation system-µC/OS, due to the different priorities in task and the real-time dispatch in management CPU, itcan finish all the tasks consequence in proper sequence. The
management CPU and DSP work in the form of principal andsubordinate style on the whole, management CPU is principal and
DSP is subordinate, executing task and obtaining parameters have toget the commands from management CPU at any time, if DSP need
to upload data forwardly, it has to send notice signals tomanagement CPU, and the management CPU will check DSPwhether there is command to deal with.
2.1 Analog experiment
In the analog experiment, the original analog output fromtransformer in dynamic simulation laboratory or relay protection
testing system is connected to this tester, then the tester will send
sampling value messages according to IEC61850 protocol to relay protection in real time one by one.
Considering the protection configuration and IEC61850 protocol requirements, analog experiment can complete on single,double side of current ,distance, longitudinal distance , longitudinalorientation and longitudinal differential line protection test, and
element protection test with two sides or three sides in transformer
protection.In order to record the condition of disturbance and protection
action in the experiment in real time, a disturbance recording tacheis added which records the changes of system voltage ,current,
analog input and GOOSE input in the experiment fully, to provide
proof for experiment and analysis of protection action. The structureof analog experiment is shown in figure 2-1.
The interface from dynamic
simulation experiment or
relay protection testing
system
Digital protective relay tester
Digital relay protection
Switch signals
Analog signals of voltage and
current
S w i t c
h s i g n
a l s
o p t i c a l f i b
e r
( G O O S E m
e s s a g e
t r a n s m i s s i o n
)
o p t i c a l f i b
e r
( s a m p l i n g v
a l u e
t r a n s m i s s i o n
)
Fig.2-1 The structure of analog experiment
8/3/2019 nps4AD3
http://slidepdf.com/reader/full/nps4ad3 3/5
2.2 Transient simulation
A transient simulation software test platform base on
ATP/EMTP is established in the tester, when the transient simulation
software runs in the background in test system, it can collecttransient current and voltage data from protected device, then thesedata is grouped frame and transmitted according to IEC61850
protocol, so the closed loop experiment is realized by detecting protection action and controlling the simulation calculator program,the structure of transient simulation is shown in figured 2-2.
Digital protective
relay tester Digital relay
protection
1. Send simulation experiment data
2.Change model and send
simulation experiment data
3.Change model again and send
simulation experiment data
Trip
Reclose
Trip forever
4.Change model at last and send
simulation experiment dataFault,Trip,Reclose,Trip forver
o p t i c a l f i b
e r
( G O O S E m
e s s a g e
t r a n s m i s s i o n
)
o p t i c a l f i b
e r
( s a m p l i n g
v a l u e
t r a n s m i s s i o n
)
Fig.2-2 The structure of transient experiment
Considering the ease-of – use for user operation, several kinds
of conventional pre-set system models are provided for users tochoose, such as line fault and transformer fault model. Meanwhile,
considering the user-opening in simulation experiment, thissimulation platform also provides all the simulation software
interface for user operation and management, if users define breaker node according to prescribed format, then a complex system modelwith their own need is built freely and put into normal operation.
2.3 Realization of sampling value transmission
To ensure the stability of the standard, IEC61850 uses
separation method of application and communication. The abstractmodel of sampling value is defined in 7-2, whose specific
communication service mapping(SCSM) is defined in 9-1 and 9-2.As the 9-1 protocol is carried out easier than 9-2 protocol, but lack
the flexible configuration like 9-2. Considering present applicationstatus, this tester will adopt the realization way of 9-1.
For the realization of 9-1 protocol, in order to ensure the hard
real-time of message transmission, without delay in communicationstack, the PDU at application layer will be encoded at presentation
layer, then it is mapped to data link layer and physical layer directly, both the transport layer and network layer is empty.(1) Application layer
According to achievement function for the tester, only 9
channel data in 12 will be realized in 9-1 protocol(because
three-phase current for protection is same with three-phase currentfor measurement), in this tester, 27 analog input channel is predefined, so before the application protocol data unit(APDU) is
placed in sending buffer, 3 application service data unit(ASDU) will
be connected for an APDU. The frame format of APDU is shown infigure 2-3.
TagASDU number
(3)Length ASDU1 ASDU2 ASDU3
APCI(Application
Protocol Control
Information)
ASDU(Application
Service Data Unit)
Fig.2-3 The APDU frame format of tester
(2) Presentation layer The data in sampling value buffer is encoded by abstract
syntax notation 1(ASN.1), the encoding format is TLV whichconsists of tag, length and value. But the APDU in 9-1 protocol uses
simple encoding, writing 0x80 for mark value, it represents thecontext class.
(3) Data link layer The Switching Ethernet is chosen, by default, the destination
of message is broadcast. The Ethernet type is set as 0x88BA, andthe priority service for message transmission is supported.
2.4 Realization of GOOSE information model
transmission
In order to ensure the reliability and real-time among kinds of intelligent electronic device(IED) communication with each other,
generic substation event(GSE) model is defined in IEC61850.Generic object oriented substation events(GOOSE) model as a kindof GSE, is mainly for trip command transmission in process bus. In
order to avoid the delay in communication stack and ensure the
rapidity for message transmission, a PDU is defined specially inapplication layer ,like sampling value transmission model, which ismapped to data link layer and physical layer without TCP/IP protocol, after encoded in presentation layer.
(1) Application layer Being different from sampling value model transmission, the
PDU on the layer uses ASN.1 standard, and it can ’t be simplified, soit depends on the support of MMS type to describe. For example,
the IMPORTS components need reference Data parameters in MMSto be described in ASN.1.(2) Presentation layer
Using ASN.1 basic Encoding Rules(BER) to encode PDU in
application layer.(3) Data link layer
It follows ISO/IEC 8802.3 protocol (Ethernet protocol),Ethernet type is set for 0x88B8, and the message transmission
priority service is support, whose default priority is 4. The particular
range of distribution of multicast addresses is allocated from01-0C-CD-01-00-00 to 01-0C-CD-01-01-FF.
2.5 Multitask scheme design under µC/OS
µC/OS is a kind of open source and free embedded operatingsystem for small and medium-sized system development [15], in
which a task is a thread and each task using CPU exclusively. Everytask is an infinite loop, it is always in the following one among 5kinds of states: dormancy state, ready state, running state, hang-up
8/3/2019 nps4AD3
http://slidepdf.com/reader/full/nps4ad3 4/5
state(waiting for event to occur), and interrupted state. Theconversion relationship among 5 states is shown in figure 2-4.µC/Os can manage 64 tasks, and 56 tasks can be used by users.Each task priority must be different, on the condition of ready state,
µC/OS always run the highest priority task, 0 for the highest, and 63
for the lowest.
hang-up
state
interrupt
ed state
ready
state
dormancy
state
running
state
interrupt
Depriving
permission
waitting
Interrupt
stop
Getting CPU
permission
Registering
task
Canceling
task
Task is
cancelled
T a s k i s
c a n c e l l e d
Resuming
task
Fig.2-4 The status switch of mission
According to the functional need analysis, two system tasks,
and three user tasks are set.
(1) "Watchdog" task: This is the highest priority task in system level,it’s also the highest priority task in the entire system, setting priority5. To ensure the stable operation of the system, the system feed thedog timely, if suddenness occurs, "watchdog" program will send a
reset signal to the system.
(2) GOOSE signal received task: another system level task, setting
priority 6. Received from the network interfaces for GOOSE signalsand delivered to the user task 2 through the message queue.
(3) User task1: it checks and verifies the command from themanagement CPU in the dual-port RAM, the priority level is set to16, and it’s delivered to user task3 through message queue, then
informs user task3 download data from dual-port RAM.
(4) User task2: GOOSE signals is received from the message queueto analyze and output through output port. Its priority is set to 17.(5) User task3: it downloads and uploads data from dual-port RAM,its priority is set to 18.
Each task transferring relationship is shown in figure 2-5.
Watchdog
GOOSE
received
Checking and
verifying data from
dual-port RAM
Receiving and
outputing GOOSE
Downloading and
uploading data
from dual-port
RAM
Fig.2-5 task priority and transferring relationship
3 Transient simulation experiment test
To check the transient simulation function of the tester, we
take ” phase-to-phase fault section I input, and recloser input” for
example, control and schedule simulation experiment after establishing the power system electromagnetic transient simulationmodel, then input corresponding message to the digital protection in
accordance with IEC61850-9 protocol, and observe the action of digital protection.
After checking and testing, the simulation experiment results
is shown in table 3-1.
Table 3-1 The simulation experiment results
Setting value(Ω) Imposed conditions Action conditions
2.85 chronic fault2.669Ω
Protection tripping
without reclosing, asshown in figure 3-1
2.54Protection doesn’t
trip
2.85transient fault
2.669Ω
Protection tripping
with reclosing, as
shown in figure 3-2
2.54Protection doesn’t
trip
2.85transient fault
2.669Ω
Failure again after
reclosing
Protection tripping
with reclosing, then
tripping forever, as
shown in figure 3-3
2.54Protection doesn’t
trip
Fig.3-1 The phase current and voltage waveform describing Protection
tripping without reclosing
Fig.3-2 The phase current and voltage waveform describing Protection
tripping with reclosing
8/3/2019 nps4AD3
http://slidepdf.com/reader/full/nps4ad3 5/5
Fig.3-3 The phase current and voltage waveform describing Protection
tripping with reclosing, then tripping forever
These waveforms tell that the transient simulation experimentfunction can complete closed-loop transient simulation testing ondigital protection successfully.
4 Conclusions
The emergence of IEC61850 to realizes interoperability
between relay protection of different manufacturers, so that moreand more Digital protection based on optical fiber communicationgradually replaced traditional protection devices.
Periodic testing on relay protection will play an extremely
important role to ensure the safe operation of power system,however, the traditional relay protection is impossible to completethe testing mission for digital relay protection. To establish a digital protective relay tester which suits new digital protection and inherits
the traditional testing method is important to ensure reliable action
on digital protection and comprehensive promotion of digitalsubstation.
The tester based on IEC61850 protocol, with two functions of
analog experiment and transient closed-loop simulation experiment,and can conduct a comprehensive digital test on digital protection.After being tested and used , it can meet using requirement in
worksite well.
References
[1] XU Ning, ZHU Yongli, DI Jian,et al. Substation automation
object modeling based on IEC61850[J]. Electric Power
Automation Equipment, 2006, 26(3):85-89.[2] DOU Xiao-bo, TAO Hong-ping, HU Min-qiang, et. Design
and realization of IEC-61850 configuration tool based on
C#.NET[J], Electric Power Automation Equipment, 2007,27(11):67-70.
[3] BIAN Peng, PAN Zhen-cun, GAO Zhan-jun, et. Applicationof SCL in remote substation configuration management[J],
Electric Power Automation Equipment, 2004, 24(4):54-56[4] DENG Peng, YOU Da-hai, WANG Jian, WANG Yang-guang,
et. MMS-based communication between IEDs and substationor dispatch center[J], Electric Power Automation Equipment,
2005, 25(11):62-65
[5] GONG Jun-qiang, HUANG Yi-zhuang, XIA Ming-chao.Application of MMS in IEDs of power system[J], ElectricPower Automation Equipment, 2004, 24(6):72-75
[6] HUANG Weisong, GE Hui. Application of file transfer
model defined in IEC61850[J], Electric Power Automation
Equipment, 2008, 28(6):111-114[7] FAN Chen, CHEN Xiao-chuan. Application of XML Schemain substation IED configuration[J], Electric Power AutomationEquipment, 2007, 27(3):120-123
[8] WU Zai-jun, HU Min-qiang. Analysis of
IEC61850-communication networks and system insubstations[J], Electric Power Automation Equipment, 2002,22(11): 70-72
[9] XU Bin, LIU Zi-ying, Design of IED based on IEC61850
standard for distribution system line protection[J], Electric
Power Automation Equipment, 2007, 27(9):103-106[10] XU Ke1, WU Zai-jun, MIN Tao, et. Digital protection
platform based on IEC 61850[J], Electric Power Automation
Equipment, 2007, 27(2):79-84[11] ZENG Cheng; shan1, HE Hai, jun, XIE Pei yuan, et. Product
platform for microcomputer protection system based onµC/OS-II and DSP[J], Electric Power Automation Equipment,
2005, 25(7):57-60[12] FENG Shuo, HUANG Mei, LI Xiao-peng. Development of
fiber digital relay protection tester based onIEC61850[J].Relay,2008, 36(8):23-25
[13] ZHAO Shun-lin. Researching and Simulation of Computer
Relay Protection Testing Device[D], Thesis of Master Degreefrom Shichuan University. 2006.
[14] DOU Xiao-bo, WU Zai-jun, HU Min-qiang. Information
Model and Mapping Implementation of Merging Unit Basedon IEC61850[J],.Power System Technology, 2006,
30(2):80-86[15] Jean J. Labrosse. μC/OS-II The Real-Time Kernel, Second
Edition, CMP Books.
Biography
CHEN Hui(1985-),male,JiangXi Nanchang,Han,Master ,the main
research directions for the Power System and its Automation。
Email:[email protected]
CHEN Jiong-cong(1979-),male,GuangXi Wuzhou,Han,Master ,
the main research directions for the Power System and its
Automation。Email:[email protected]
LIANG Xiao-bing(1973-),male,HeBei Tangshan,Han,Master ,
the main research directions for the Power System and its
Automation。Email:[email protected]
YU Nan-hua(1976-),male,JiangXi Jiujiang,Han,Doctor ,the main
research directions for the Power System and its Automation。
Email:[email protected]