Planning of HVDC System Applied to Korea Electric Power Grid

Abstract

This paper proposes pre-analysis on planning of high-voltage direct current (HVDC) transmission system applied to Korea electric power grid. HVDC transmission system for interface lines has been considered as alternative solution for high-voltage AC transmission line in South Korea since constructing new high-voltage AC transmission lines is challenging due to political, environmental and social acceptance problems. However, the installation of HVDC transmission system as interface line in AC grid must be examined carefully. Thus, this paper suggests three scenarios to examine the influences of the installation of HVDC transmission system in AC grid. The power flow and contingency analyses are carried out for the proposed scenarios. Power reserves in metro area are also evaluated. And then the transient stability analysis focusing on special protection scheme (SPS) operations is analyzed when critical lines, which are HVDC lines or high voltage AC lines, are tripped. The latest generic model of HVDC system is considered for evaluating the impacts of the SPS operations for introducing HVDC system in the AC grid. The analyses of proposed scenarios are evaluated by electromechanical simulation.

Fig. 1. Planned power plant in east-sea side and theproposed transmission for its installations in theKorea electric power grid

Fig. 2. Generator angle responses when two 765 kV T/L #3lines are tripped: (a) without generator trip; (b) with1 generator trip

Fig. 3. Bus voltage responses when two 765 kV T/L #3lines are tripped: (a) without generator trip; (b) with1 generator trip

Fig. 4. Transmitted power responses with 1 generator tripwhen two 765 kV T/L #3 lines are tripped

Fig. 5. Generator angle responses in SN 2 when 765 kVT/L #1 two-lines are tripped: (a) 2 generators trip;(b) 3 generators trip

Fig. 6. Bus voltage responses in SN 2 when 765 kV T/L #1two-lines are tripped: (a) 2 generators trip; (b) 3generators trip

Fig. 7. HVDC responses when 765 kV T/L #1 two-lines aretripped with 3 generators trip: (a) active power; (b)reactive power; (c) alpha; (d) gamma; (e) DCvoltage; (f) DC current

Fig. 8. Generator angle responses when 765 kV T/L #3two-lines are tripped in SN 3: (a) without generatortrip; (b) 1 generator trip

Fig. 9. Bus voltage responses when 765 kV T/L #3 two-lines are tripped in SN 3: (a) without generator trip;(b) 1 generator trip

Fig. 10. HVDC responses when 765 kV T/L #3 two-linesare tripped with 1 generator trip: (a) active power:(b) reactive power; (c) alpha; (d) gamma; (e) DCvoltage; (f) DC current

Fig. 11. (a) Generator angle; (b) Bus voltage when 765 kVT/L #1 two-lines are tripped with 2 generators tripby applying overload capability

Fig. 12. HVDC responses when 765 kV T/L #1 two-linesare tripped with 2 generators trip by applyingoverload capability: (a) active power; (b) reactivepower; (c) alpha; (d) gamma; (e) DC voltage; (f)DC current

Table 1. Proposed scenarios of interface transmission systems for planned generations

Table 2. Interface power flows and interface line loadings of SN 1 in N ？ 1 contingency

Table 3. Interface power flows and interface line loadings of SN 2 in N ？ 1 contingency

Table 4. Interface power flows and interface line loadings of SN 3 in N ？ 1 contingency

Table 5. Power reserve in metro area with the proposed scenarios

Table 6. SPS analyses of critical line trip on SN 1

Table 7. SPS analyses of critical line trip on SN 2

Table 10. SPS analyses of critical line trip on SN 3