Smart Grid Standards. Dr.-Ing. Abdalkarim Awad Informatik 7 Rechnernetze und Kommunikationssysteme

Transcription

1 Smart Grid Standards Informatik 7 Rechnernetze und Kommunikationssysteme

2 Some Smart Grid Related Standards IEC and DNP3: Substation IEC 61698/61970: Transmission and distribution IEC 61400: Wind Turbines IEEE : PMU OpenADR: Automated Demand Response ZigBee: Home Automation BACnet: Building Automation 2

3 Distributed Network Protocol DNP3 DNP3 becomes IEEE 1815 Set of communication protocols between data acquisition and control equipment It plays a crucial role in SCADA systems Used by control centers, RTU and IEDs It has five layers Master/slave Originally the physical layer used serial communication, but now Ethernet can be found user Application Transport Data Link Physical 3

4 IEC 61850: Substation IEC: International Electrotechnical Commission Communication Networks and Systems in Substations Was developed to provide inter-operability intelligent electronic devices (IEDs) for: Protection, Monitoring, Control and automation in substations Addresses Communications and Information modeling 4

5 IEC primary parts Part 6-1: Substation Configuration Language (SCL) Part 7-2: Abstract Communications Service Interface (ACSI) and base types Part 7-3: Common Data Classes (CDC) Part 7-4: Logical Nodes Part 8-1: Specific Communications Service Mappings (SCSM) -MMS & Ethernet Part 9-2: SCSM -Sampled Values over Ethernet Part 10-1: Conformance Testing 5

6 Three IEC61850 Protocols MMS (Manufacturing Message Specification) GOOSE (Generic Object Oriented Substation Event) SV (Sampled Values) 6

7 The Power Substation 7

8 The Power Substation Circuit Breaker (CB) 8

9 Intelligent Electronic Device (IED) Microprocessor-based controllers of power system equipment e.g. circuit breaker, protective relay... Receive digitalized data from sensors and power equipment Issue control commands in case of anomalies to maintain the desired status of power grid e.g. tripping circuit breakers 9

10 Example 10

11 IEC Standard in Substation Autmation MMS GOOSE Sampled Values 11

12 Example Source: esting.html 12

13 Industrial Ethernet Network 13

14 Prioritization In IEC control applications, it is required that the control message transfers occur within 3 ms. Faults can produce a data message storm. Strict priority. 14

15 Generic Substation Events (GSE) Generic Substation Events (GSE) Control model defined in IEC Provides a fast and reliable mechanism of transferring event data over the complete substation networks Multicast GSE subdivided into GOOSE (Generic Object Oriented Substation Events) GSSE (Generic Substation State Events). SV (Sampled Values) 15

16 GOOSE: Generic Object Oriented Substation Event GOOSE messages are sent when event occurs Publisher/Subscriber model Ethernet message (not TCP/IP) Multicast and priority tagging To guarantee delivery, GOOSE message is sent several times No ACK Examples of GOOSE messages : - Autoreclosing (between relay and BCU/CB) - Intertripping (between relay and relay) - Blocking (between relay and relay/bcu) - Interlocking (between BCU and BCU) 16

17 Sampled Values Similar to GOOSE Transmits high speed streams of data set samples encoded in multicast or unicast Ethernet frames. The protocol uses a publisher/subscriber model, in which a publisher transmits unacknowledged data to subscribers. Periodic (4000 sample per second) 17

18 Communication Stack of IEC Time Critical SV GOOSE SNTP MMS TCP/IP TCP/IP Ethernet Link Layer (with Priority, VLAN) Ethernet 100 MB/s Fiber 18

19 GOOSE and SV messages Application layer directly accesses link layer for speed no TCP/IP Uses Ethernet frame directly with Priority/VLAN 802.1Q tag Use priority 4 due to criticality or messages. VLAN use is optional. Fields in payload - source ID, status bits, analog values, time stamp, sequence number, time to live, quality bits, test modes. Typical packets bytes long. Preamble DA SA 1Q tag Type Payload FCS TPID PCP DEI VID 12 bit 3 bits 1 bit 12 bit TPID: Tag Protocol Identifier PCP: Priority Code Point DIE : Drop Eligible Indicator VID: VLAN identifier 19

20 Drivers for Wide Area Monitoring To avoid large area disturbances To improve usage of existing power transfer capacity To secure power system integrity 20

21 Wide Area Monitoring 21

22 Structure Data acquisition, carried by Phasor Measurement Units (PMU) Data delivery through wide area communication system to PDC-Phasor Data Concentrator Data Processing, through the system protection Center (SPC) Command delivery Command execution 22

23 Measures Voltage, Current, phase PMU1 IEEE C WAN PDC Historian Phasor Data Concentrator HMI App1 PMU2 APn Bay1 Bayn LAN e.g., DNP3 Modbus IEC60870 Substation Automation System WAN Command Data e.g., DNP3 Modbus IEC60870 PDC-Phasor Data Concentrator HMI -Human Machine Interface LAN -Local Area Network PMU -Phasor Measurement Unit Dr.- Ing. Abdalkarim Awad 23

24 Architecture SuperPDC PDC PDC PMU PMU PMU PMU PMU 24

25 Phasor Measurement Unit (PMU) The phasor measurement unit (PMU) is a power system device capable of measuring the synchronized voltage and current phasor in a power system. Synchronicity among phasor measurement units (PMUs) is achieved by same-time sampling of voltage and current waveforms using a common synchronizing signal from the global positioning satellite (GPS). The ability to calculate synchronized phasors makes the PMU one of the most important measuring devices in the future of power system monitoring and control 25

26 Synchronized Measurements A PMU at a substation measures voltage and current phasors: Very precise synchronization with μs accuracy. Compute MW/MVAR and frequency. Measurements are reported at a rate of times a second. Can track grid dynamics in real time Traditional SCADA refresh rate is seconds to minutes 26

27 Phasor Data Concentrator (PDC) Each utility has its own Phasor Data Concentrator (PDC) to: Aggregate/align data from various PMUs based on time tag Measurements from each utility s PDC is sent to the Central Facility: Where the measurements are synchronized across utilities 27

28 OpendPDC Complete set of applications for processing streaming time-series data in real-time Measured data is gathered with GPS-time from multiple input sources, time-sorted and provided to user defined actions, dispersed to custom output destinations for archival The openpdc implements a number of standard phasor protocols which can be used to receive data from devices. The supported protocols:ieee C37.118, IEEE 1344, BPA PDCstream, FNET, SEL Fast Message, 28

29 PMU for Wide Area Monitoring and Control Potential PMU Applications Wide-Area Visualization and Monitoring; Angle and Frequency Monitoring; Inter-area Oscillation Detection & Analysis; Proximity to Voltage Collapse; State Estimation; Fast Frequency Regulation; Transmission Fault Location Estimation; Dynamic Model Validation. 29

30 PMU Block Diagram Functional block diagram of the elements in a PMU. 30

31 Phasor: reminder A pure sinusoidal waveform can be represented by a unique complex number known as a phasor. A sinusoidal signal x( t) Xmcos( t ) The phasor representation of this sinusoid is given by Xm j Xm x( t) e (cos( ) sin( ))

32 Phasor: reminder Classical Definition of a Phasor The RMS cosine-reference voltage and current phasors are. 32 i j v j I e I I V e V V i v

33 Convention for synchrophasor representation 33

34 Phasor If the sinusoid is not a pure sine wave, the phasor is assumed to represent its fundamental frequency component. The most commonly used method of calculating phasors from sampled data is that of Discrete Fourier Transform (DFT). 34

35 Important of the Phasor Measurement P 1 V 2 * V 1 2 X L sin Bus1 XL Bus2 V1 PMU1 PMU2 V2 35

36 Compute MW & MVAR j v V V e V v v j i I I e I i i P VI cos( ) v i Q VI sin( ) v i 36

37 Synchronized Measurements Location 2 Location 1 Phase angular difference between the two buses can be determined if the two local clocks are synchronized. Synchronizing pulses obtained from GPS satellites. 37

38 Role of GPS Constellation of 24 satellites orbiting at 20,200 km Developed by US dept of defense Available for free for civilian use Beyond navigation use, it provides time reference: Protection systems derive usage of GPS from the timing signal 4 satellites are needed for knowing timing and location position Satellites have atomic clocks Provides coordinated universal time (UTC) which is international atomic time compensated for leap seconds for slowing of earths rotations can obtain accurate timing pulse every second with an accuracy of 1 microsecond 38

39 PMU Facts PMU uses discrete Fourier transform (DFT) to obtain the fundamental frequency components of voltage / current(half cycle or Full cycle) Data samples are taken over one cycle / multiple cycles. Resolution of the A / D converter is 16 bits. 39

40 Example Power Flow= 5 pu Frequency=50 The power is estimated using bus 1 and 2 (Φ1-Φ2) Error of time stamp at 1 is 0.1 ms and at bus2 is 0 Find the error in estimated power Bus1 j0.1 Bus2 V1=1.0 PMU1 PMU2 V2=1.0 40

41 Example 0.1 ms corresponds to: θ=(0.1ms/20ms)*2π = rad V1V 2 P sin( 1 2) X 10sin( ) Feq=50 Hz 41

42 Example P P V1V 2 sin( 1 2 X pu ) V1V X 2 sin( )

43 Signals with 50 and 51 Hz Blue: Cos(2*π*50*t) Red: Cos(2*π*51*t) 43

44 Table of synchrophasor values at a 10 fps reporting rate Fps: Frame per second 44

45 Relevant PMU Standards C A general transient data recording file format standard C a complete revision and dealt with issues concerning use of PMUs in electric power systems C Covers synchrophasor measurements for power systems Adds frequency & rate of change of frequency (ROCOF) and dynamic operation C Dr.-Ing. Defines Abdalkarim real-time Awad synchronized phasor measurement 45

46 C

47 Example of frame transmission order The SYNC word is transmitted first and CHECK word last. Two- and four-byte words including integer and floating-point numbers are transmitted most significant byte first (network or big endian order). All frame types use this same order and format. 47

48 Required PMU reporting rates 48

49 Word definitions common to all frame types 49

50 Word definitions common to all frame types 50

51 Sync (2 bytes) Frame synchronization word. Leading byte: AA hex Second byte: Frame type and Version, divided as follows: Bit 7: Reserved for future definition Bits 6 4: 000: Data Frame 001: Header Frame 010: Configuration Frame 1 011: Configuration Frame 2 100: Command Frame (received message) Bits 3 0: Version number, in binary (1 15), version 1 for this initial publication. 51

52 Word definitions common to all frame types 52

53 Example A PMU sent a packet that starts with following four bytes (decimal) 170,49,1,198 What is the 170? Determine the type of frame? Data Configuration Command header What is the size of the frame? 53

54 Example 170=0xAA (0x mean hexadecimal) It is the SYNC byte 49=0x31= b 0 (Bit 7: Reserved for future definition) 011: configuration frame : version 1 It is a configuration frame (Config-2) and the version (1) Then comes the two bytes size Size=198+1*256=

55 Configuration frame 55

56 Configuration frame 56

57 Word definitions unique to configuration frame 57

58 To send a value (e.g., voltage) It is possible to send it as a float or integer If Integer We need to scale it Example: to send as 16 bit integer Scale it e.g 1000*18.45=18450 At the receiver side: we convert it back using the same scale 18450/1000=18.45 In C37.118, PhasorMag=value*PHUNIT/

59 FORMAT (2 Bytes) Data format in data frames, 16-bit flag. Bits 15 4: Unused Bit 3: 0 = FREQ/DFREQ 16-bit integer, 1 = floating point Bit 2: 0 = analogs 16-bit integer, 1= floating point Bit 1: 0 = phasors 16-bit integer, 1 = floating point Bit 0: 0 = phasor real and imaginary (rectangular), 1 = magnitude and angle (polar) 59

60 Example Explain the following two bytes for FORMAT field First byte (MSB)= 0 Second byte=8 So we have Bits 15 4: Unused Bits 3 0: Bit 0=0 phasor real and imaginary (rectangular) Bit1=0 phasors 16-bit integer Bit2=0 analogs 16-bit integer Bit3=1 FREQ/DFREQ 32 bit float 60

61 PHUNIT (4 bytes) Conversion factor for phasor channels. Four bytes for each phasor. Most significant byte: 0 = voltage; 1 = current. Least significant bytes: An unsigned 24-bit word in 10 5 V or amperes per bit to scale 16-bit integer data. (If transmitted data is in floating-point format, this 24-bit value should be ignored.) 61

62 62

63 Data Frame Data frame organization 63

64 PHASORS(4/8) 16-bit integer values: Rectangular format: Real and imaginary, real value first 16-bit signed integers, range to Polar format: Magnitude and angle, magnitude first Magnitude 16-bit unsigned integer range 0 to Angle 16-bit signed integer, in radians 10 4, range to

65 PHASORS(4/8) 32-bit values in IEEE floating-point format: Rectangular format: Real and imaginary, in engineering units, real value first Polar format: Magnitude and angle, magnitude first and in engineering units Angle in radians, range π to +π 65

66 FREQ(2/4) Frequency deviation from nominal, in millihertz (mhz) Range nominal (50 Hz or 60 Hz) to Hz 16-bit integer or 32-bit floating point. 16-bit integer:16-bit signed integers, range to bit floating point: actual frequency value in IEEE floating-point format. 66

67 Example If the voltage is Determine the content of the PHASORS bytes for the same FORMAT in the previous example and the PHUNIT has the following 4 bytes (0,0,47,175) Based on the format field, we have to send the phasors as 16 bit Byte0=00 (most significant Byte) Byte1=00 Byte2= Byte3=175 PHUNIT=47* =

68 Example Vr= Vi=0 Before sending, we have to scale the value ScaledVr=Vr*100000/12207=20729 This value is 16 bit We have to send each byte ScaledVr=20729=0x50F9 ScaledVi=0=0x

69 Example We have to send the real part and then the imaginary part, therefore Fist byte=0x50=80 Second byte=0xf9=249 Third byte=0x00 Forth byte=0x00 The PDC will do 80* = *12207/ =

70 Cyclic redundancy codes (CRC) CRC-CCITT g(x) = x 16 + x 12 + x

71 Communication options: Serial IP protocol x message TCP/UDP header x message IP header TCP/UDP header x message Transp. header IP header TCP/UDP header x message Transp. trailer OPTIONS: TCP only, UDP only, TCP/UDP 71

72 Bibliography High Performance IEC GOOSE and Protection Relay Testing by Hachidai Ito and Kenichiro Ohashi, Toshiba Corporation, Japan IEEE C Standard Smart Grid: Technology and Applications, 2012, ISBN , Wiley, by Janaka Ekanayake, Kithsiri Liyanage, Jianzhong Wu, Akihiko Yokoyama, Nick Jenkins Smart Grid : Applications, Communications, and Security by Lars T. Berger and Krzysztof Iniewski Hamed Mohsenian-Rad, Communications & Control in Smart Grid (Slides) 72