The number of faults The percentag e of fault
38
2196
45
0.83％
4.49%
1.58%
91.23%
1.86%
Chinese 220kV power transmission line fault statistics in 2008
Basic Principles and Elements of Relay Protection
use electricity
Electrical equivalent model
Power station Turbine Generator Substation boosting transformer
Substation step-down transformer
Load
Reservoir
Logic circuits
Operation circuit
Tripping signal
The block diagram of relay protection device
The requirement of relay protection
A QF1 B QF2 QF5 C QF6 k1 D
S k S k max U imin U i U k max I ij I ijmax f min f f max
Abnormal Operation Condition
Over voltage low voltage
Overload The common abnormal state
NARI RCS-900 line protection device
NAS9210 series integrated protection device
Relay protection cabinet
Electric parameters being tested
Measurement circuit
State of Fault
Standard of Normal Operation Condition
Equality constraint ：
P P P 0 Q Q Q 0
Gi Lj S Gi Lj S
Inequality constraint ：
G
Transmission line
Power net Power system
M M
Dynamic system
Three state of power system
1 2 3
Standard of Normal Operation Condition
Abnormal Operation Condition
power network dispatching
Application server
RTU
Data acquisition and transmission
RTU RTU
generate power

transmit electricity
transformate power
distribute power
Relay protection of power system
--School of Energy Science and Engineering --ChenYu
Structure
1 2
Introduction of power system
Three state of power system
State Grid Corporation
North China 500KV AC(3) 2001 1900 MW ±500KV DC(3) 1989 / 2003/2207 7200 MW
South China
Taiwan
±500KV DC(1) 2004 / 02 3000 MW
Power system
3 4
Basic Principles and Elements of Relay Protection
The requirement of relay protection
Grid interconnection
500KV AC(2) 2006 / 06 1200 MW 500KV AC(1) 2003 / 09 800 MW Northwest Tibet East China Central China 120KV DC(1) 2005 / 06 360 MW 500KV AC(2) 2001 / 05 1200 MW Northeast
Oscillation
frequency increase
frequency step down
State of Fault and Its Threats
Fault type Threephase short circuit 20 Two phase short circuit 108 Two phase short circuit grounding Single phase grounding short circuit Other faults
QF3
QF4
Reliability
Speed
Selectivity
Sensitivity