| Title |
Derivation of Minimum Sending-end Voltage for Constant Load P+jQ in AC Two-bus System |
| Authors |
Gene-Que Lee ; SangJoong Lee ; JuChul Kim |
| DOI |
http://doi.org/10.5207/JIEIE.2022.36.10.036 |
| Keywords |
AC two-bus system; Constant power load; Discriminant; Minimum sending-end voltage |
| Abstract |
For a series circuit with a voltage source and a constant power load connected by an impedance, the magnitude of voltage source must be equal to or greater than a specific threshold value in order to feed its load. This implies that the minimum magnitude of source voltage depends on the magnitude of load power. This paper shows a two-bus power system which is composed of a voltage source, a transmission line impedance and a constant power load. And the authors find out the minimum sending-end voltage that enables the voltage source to successfully feed its load in example calculation. A formula for obtaining the minimum sending-end voltage in general two-bus system with load P+jQ and line impedance r+jx, is also proposed. We have been more accustomed to a load represented by constant impedance, however, in power systems, the loads are represented by kVA or P+jQ in general. The two-bus system can be interpreted as a Thevenin’s equivalent that has a constant power load instead of the external impedance load. In this case, the constant power load can be interpreted as the total consumers’ demand in a power system, and the minimum sending-end voltage can be interpreted as the least system voltage which the power provider must maintain to keep the entire system from voltage collapse. The proposed formula can be a useful tool for power system analysis. |