RCS-931A UHV transmission line protection equipment

RCS-931A/B High Speed Protection for UHV Transmission Line

Application

RCS-931A/B is a microprocessor based protection equipment used for main and back-up high speed protection of 220 kV or more UHV transmission line.

Composition

The equipment comprises following parts:

  • High-speed main protection including phase-segregated current differential relay, zero sequence differential current relay and fast zone I of DPFC distance relay;
  • Backup protection including three zones phase-to-phase distance relay, three zones ground distance relay and two delayed zones of zero sequence directional overcurrent relay for RCS-931A; three zones phase-to-phase distance relay, three zones ground distance relay and four delayed zones zero sequence directional overcurrent relay for RCS-931B;
  • Single pole, 3 pole and 1/3 pole auto-reclosing for circuit breakers of single or double busbar configuration.

Outputs of the protection are phase-segregated.

General

  • The equipment uses an integral front panel and closed cabinet with high immunity. The wiring on the panel is simplified by using connectors for external connections. Commissioning and configuration in the site could be done convemiently by dedicated tuning and testing instrument developed by our company.
  • DSP and monolithic computer modular design are used for the equipment. The DSP performs protection algorithm and logic discrimination functions. The monolithic computer performs general starter, communication, event record, oscillogram record and other auxiliary functions. Data acquisition of these two parts are independent to each other. Positive pole of power supply of output relays could be closed only when the general starter starts. So unwanted operation of the protection due to any single component failure could be avoided.
  • On the premise of higher sampling rate 24 points per cycle, all protection calculation and logic discrimination could be done within one sampling period due to parallel calculation for all protection relays. Principal relays adopt complete cycle Fourier algorithm with high reliability and security. Event record and protection logic calculation are completed simultaneously and no mistake could be caused in the record due to operation of various CPUs during complicated fault conditions.
  • Man-machine interface consisted of LCD and a 9 button keypad on the panel is ver friendly to the user. A serial port is equipped for communication with PC. Commissioning and configuration could be done more conveniently on PC.

Features

  • High capacity memory and high speed DSP is adopted. Design of hardware is meticulous, succinct, reliable and with high redundancy. Power frequency circuit and electronic circuit are divided entirely so high electromagnetic compatibility could be got.
  • Operating speed is very high: 10 ms for close-by fault, 15 ms for middle part fault and 25 ms for remote fault.
  • Phase-segregated DPFC current differential relay is performed in this equipment with high operation speed and high reliability.
  • Capacitive current could be compensated accurately by data from both ends.
  • Sensitivity of the protection performed by zero sequence current differential relay and steady state compensated current differential relay is very high. It could select faulty phase correctly during high resistance fault condition.
  • Permissive command will be sent between differential protection at both ends during fault condition and reliability of the equipment is very high.
  • The equipment uses relative high ratio restraint and adaptive floating threshold. These make it high performance on anti-saturation of potential transformers.
  • The differential protection could adapt to change of power system operation mode. It suits double circuit installed on same pole and series compensated transmission line.
  • The DPFC distance relay has high operation speed and high reliability. It suits series compensated transmission line.
  • Swing blocking function of DPFC distance relay is perfect.
  • Capacity of the recorder is high enough. Information recorded is complete, safe and reliable. Format of the record is compatible with international COMTRADE format.
  • The equipment is equipped with ether net port and RS-485 serial ports and supports protocol IEC 60870-5-103.

Technical data

Ratings
DC control voltage 220 V, 110 V
Tolerance +15% - -20%
AC voltage 100 V /3
AC current 5 A, 1 A
Line voltage for recloser
100 V, 57.7 V
Frequency 50 Hz
 Protection relays (cont'd)
DPFC distance relay
Operation time < 10 ms (Uop >2Uz)
Pick-up range for impedance
0.1- 25 (In = 5 A)
0.5- 125 (In = 1 A)
Zero sequence directional relay
Minimum operating current
0.1 In
Minimum operating voltage
0.5 V -1 V
Zero sequence overcurrent relay
Pick-up range 0.1 In - 20 In
Tolerance < 5%
Range of time delay of delayed zones
0 s - 10 s
Distance protection
Pick- up range for impedance
0.01- 25 (In = 5 A)
0.05- 125 (In = 1 A)
Tolerance < 5%
Accurate operating voltage
< 0.25 V
Minimum accurate operating current
0.1 In
Maximum accurate operating current
30 In
Range of time delay of delayed zones
0 s - 10 s
Power consumption
AC current circuit at rated current
< 0.5 VA / ( In = 5 A)
< 0.25 VA / ( In = 1 A)
AC voltage circuit at rated voltage
< 0.5 VA /
DC control circuit quiescent < 20 W
energized < 35 W
Operation time of complete equipment
DPFC distance element
Close-by 3 - 10 ms
Middle part < 15 ms
Zone I of distance protection
20 ms
Pilot protection for whole line
< 25 ms
Starter
Pick-up range of I starter
0.1 In - 0.5 In
Pick-up range of zero sequence current starter
0.1 n - 0.5 In
Protection relays
Current differential relay
Restraint factor 0.75
DPFC directional relay
Minimum operating current
0.2 In
Minimum operating voltage
5 V
 Fault location
Accuracy 2.5%
Auto-recloser
Phase difference of synchronism checking
0-90,tolerance<3
Live line detector
Pick-up value >40 V, tolerance < -2 V
Dead line detector
Pick-up value <30 V, tolerance <+1.5 V
Recorder
Number of events to be recorded
128
Number of oscillograms to be record
24		 EMC test (cont'd)
Electrostatic discharge
IEC 60255-22-2, classIII
Fast transient disturbance
IEC 60255-22-4, classIV
Radiated electromagnetic field
IEC 60255-22-3, classIII
10 V/m, ( 25-1000 ) MHz
Number of groups of setting value
30
Communication
Serial port 2, ether net or RS-485
Port for time synchronism with GPS
1
Port for printer 1, local or network printer
Protocol IEC 60870-5-103
 Insulation test
Insulation IEC 60255-5
2 kV, AC, 1 min
Impulse IEC 60255-5
5 kV, 1.2/50s, 0.5J
Ambient temperature
Normal operation -5- 40
Extreme range - 10- 55		 Chassis
Weight 10 kg
Dimensions width 482.6 mm (19'')
height 177.8 mm (4U)
depth 325 mm
Flush type mounting, panel cutout
451 mm179 mm
EMC test
1 MHz bursts disturbance
IEC 60255-22-1, classIII