Partitioning-Based Unified Power Flow Algorithm for Mixed MTDCAC Power Systems
Abstract : This paper presents a unified power flow algorithm for large and complex mixed AC/DC power systems based on the partitioning of power grids, a version of the two-level Newton method, and the modified nodal analysis formulation. Partitioning significantly increases numerical efficiency without altering the accuracy of the power flow solution. This approach can be applied to any combination of multiple DC and possibly non-synchronized AC systems. It considers the steady-state interaction of AC and DC systems for a wide range of converter representations and control functions. Simplification of elements within the converter stations is not required. Both DC and AC-side converter losses are adequately accounted for by using a generalized converter loss model. The steady-state converter equations are derived in their most general form, with the AC and/or DC-side power exchange or voltages defined as controlled quantities.
? It improves the dynamic performance of the existing variable impedance type FACTS devicevia co-ordination with switching converter based FACTS devices.
? Application of power electronic devices in the form of flexible AC transmission system (FACTS) helps in achieving this target – operating the existing transmission system closer to its thermal limit.
? The current situation of power system presses for new installation of UPFC and/or replacement of existing SVC and TCSC by the UPFC.
? The investment cost is considerably reduced by using an existing FACTS device. Also, the existing SVC or TCSC is fully utilised with enhanced compensating functions.
? It improves the dynamic performance of the existing variable impedance type FACTS devicevia co-ordination with switching converter based FACTS devices.
? Application of power electronic devices in the form of flexible AC transmission system (FACTS) helps in achieving this target – operating the existing transmission system closer to its thermal limit.
? The current situation of power system presses for new installation of UPFC and/or replacement of existing SVC and TCSC by the UPFC.
? The investment cost is considerably reduced by using an existing FACTS device. Also, the existing SVC or TCSC is fully utilised with enhanced compensating functions.
• This makes the idea of the Hybrid Power Flow Controller (HPFC) proposed in an alternative solution without substantial compromise on versatility.
• It is important to ascertain the location for placement of UPFC which is suitable for various contingencies. An effective placement strategy for UPFC is proposed .
• The method uses Line Stability index which is sensitive to line flow to screen down the possible locations for UPFC.
• The Unified Power Flow Controller (UPFC) was proposed first time for real turn-off time control and dynamic compensation of ac transmission systems.
? A conventional UPFC system is a combination of a STATCOM and SSSC, which share a DC link capacitor, and comprises two transformers and two power converters, which are bulky and expensive.
? Consequently, although their performance is outstanding, the use of conventional UPFCs has been limited because of these shortcomings.
? Therefore, the use of conventional UPFCs has been limited, although their performance is outstanding. Consequently, the demand for a smaller, lower-cost topology has increased.
? By synthesizing an appropriate injection voltage, the performance of the power flow control could be verified.
? The voltage of the DC link was controlled well according to the reference of 150 V.
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