Vol: 1 Issue: 1
DETERMINING LOAD FLOW ANALYSIS FOR A HYBRID POWER SYSTEM USING NEWTON RAPHSON’S ITERATIVE APPROACH.
Ekum, A. Eyam and Archibong, E. Etim
1. INTRODUCTION
Up until recently, most power systems were unidirectional, transferring generated electricity from transmission systems to distribution systems, where customers are connected. However, there is now a bidirectional power flow because electricity may be produced and used within the distribution system [1]. EV charging stations might also act as generators to feed extra energy to the utility grid, while battery systems could act like loads when they are being charged. As a result, the system as a whole becomes more complicated and the electrical power system develops into an intelligent, AC/DC hybrid system. Given that existing distribution systems must evolve to accommodate the growing use of DC generators and loads, it follows that the conventional AC-oriented power flow analysis must also adapt to meet the new needs of a hybrid power system. Numerous studies on the AC/DC load flow are provided, with a focus on high voltage DC (HVDC) transmission systems, but these techniques are not convenient for hybrid distribution systems since they perform poorly in systems where DC bus penetration is significant, which makes the algorithm more complex. Future smart AC/DC distribution systems are likely to have numerous intersecting AC and DC nodes, branches, different AC or DC generators, and coupled loads, so decoupled methods that divide the main AC/DC grid into several sub-grids might not be appropriate to use for coupled AC/DC distribution systems [1]. Additionally, it is noted in [2] that the sequential technique is more difficult than the unified method, may sometimes have convergence issues, and requires more time to solve since the whole AC solution must be computed each time a parameter on the DC side is changed. Additionally, it is shown for the sequential technique that as the number of repetitive loops rises, algorithm dependability declines and complexity increases [3]. Due to its quadratic nature, the Newton-Raphson iterative technique has the benefit that it converges more quickly than other methods. Since AC/DC distribution systems include AC and DC microgrids, this presentation has focused on an integrated technique for load flow analysis. The suggested method contributes by using AC/DC voltage source converters to present a Newton-Raphson-based iterative method for overall system-level power transfers between AC and DC sub-networks, and by taking into consideration various connection types in a hybrid distribution system with DC/DC converters. The suggested load flow approach may acquire power flow across converters linked at various buses while accounting for all converter losses. By integrating AC and DC line flows, this technique reduces the complexity of the algorithm and has the benefit of a quicker convergence time with excellent accuracy when compared to other techniques. For AC/DC distribution systems, the researchers of [4] suggested a unified load flow analysis technique based on the reduced gradient method. However, the technique lacks models for DC/DC converters, and converter operating modes like constant voltage control and constant duty ratio are disregarded. A-dditionally, DC/DC converters are used in constant duty ratio and constant output voltage modes. Because the equations provided are general, the suggested approach may be applied to various converter types [5].