Online detection and locating of faulty nodes using
ONLINE DETECTION AND LOCATING
OF FAULTY NODES USING HF SIGNAL
INJECTION IN SMART GRIDS
Mr. Labeeb .M
Asst. Prof. EEE Dept.
Demerits of Conventional methods of fault detection.
Fault detection using High Frequency signal injection .
Fault in a power system is an un predictable situation that
will lead to un balance in overall power system.
Common reason for establishing faulty nodes in power
system network are SLG,LL,LLG faults and Electricity theft.
Detection and localization of faulty node in a power system
has great importance in current scenario.
Impact on utility supply providers budget.
Early locating of fault and restoration of supply ensure safety
As far as quality of supply is considered detection and locating
of faulty node has to be done without interrupting the supply.
HF signal injection method is most suitable for online fault
DEMERITS OF CONVENTIONAL
Need high calibrated energy meters.
De- energization of Network is required.
Inability to apply on short range and multi layer networks .
FAULT DETECTION THROUH
HF SIGNAL INJECTION
An online method.
Communicate between Consumer and central unit through
Use A-band signal (3-95KHz) injection.
SMART METER REQUIREMENTS
High bandwidth meter transducer .
Facility to ascertain basic quantities-
V,I and f
PLC/ ZIGBEE / GSM
CENTRAL UNIT REQUIREMENTS
Predetermined information regarding
Number of nodes
Impendence between nodes at HF
PLC GSM ZIGBEE
High voltage coupler.
Current injection unit.
CURRENT INJECTION UNIT
CENELEC standard EN50065-1 limits imposed
voltages on nodes less than 1V
Injected current value is set based on estimated line
impedance to meet the standard.
Load flow analysis at High frequency(HF) is done for
detection an locating of faulty node
Test signal at high frequency is send to the network
Load impendence are calculated at high frequency for load
Load impedance at power frequency is converted to impdence
at high frequency using load models.
ZLi = 𝑅Li+j 2𝜋𝑓LLLi
𝐴 = 𝜋𝑟2
IMPEDENCE TRANSFORMATION (Contd..)
𝑍 𝐿𝐻 𝑓 = 𝐻 𝑓 𝑍 𝐿
𝑍 𝐿𝑖=Load impedance of 𝑖 𝑡ℎ node at power frequency
𝑓𝐿= Power frequency
𝑆𝑖=Apparent power at 𝑖 𝑡ℎ
𝑃𝑖=Real power at 𝑖 𝑡ℎ node
Measured load impendence are send to central unit for load
Predetermined impedance between nodes are combined with
load impedance at HF to form admittance matrix.
Central node develop new admittance matrix each time it get
new HF load impedance from smart meter.
𝑌𝑖𝑖 = 𝑘=0
𝑌𝑖𝑘 where i≠k
Ii=0 for Ii ≠1 for HF domain
From calculated impedance matrix central unit calculate
voltage at individual nodes (Vbus) using load flow analysis.
Periodically measured node voltage due to HF signal using
smart meter is stored in central unit as Vmeas matrix.
FAULT DETECTION AND
Predicted value for node voltage for test signal injection=Vbus
Node voltage measured using smart meter=Vmeas
If there is no fault Vdiff=0
∀ 𝑥 ∈ 𝑉𝑑𝑖𝑓𝑓 : if x ≥VT 𝑥 ∈ 𝐹𝑁𝐴
∀ 𝑥 ∈ 𝐹𝑁𝐴: if xi > xk k≠ 𝑖 xi=FN
FAULT DETECTION AND LOCALIZING
Graph showing fault near to node 34
The high frequency test signal injection method can be
used in live network without interfering the supply. This online
fault detection and localizing method is based on the analysis of
network characteristics using power flow analysis at high