Power Analysis for a Limited Bus Grid System with Distribution Generators

Abstract

It has been recognized recently that when injecting renewable energy source power to a load buses which connected to some distributed feeders in a power grid system, a stability problem occurs particularly when having high fault duties that exceeding the circuit breaker ratings at some substations. In this paper an analysis of power flow, short circuit, stability and protection are given in detail to an example of limited 7-bus power grid system. Comparison are illustrated between power grid with and without distributed generators regarding bus voltages, fault currents, critical power angles, selected current transformers and over current relay settings in each bus. It discusses the selection of optimum slack bus in Gauss Seidel method, and shows that the system with distributed generators is more stable although the fault currents are higher than the system without distributed generators.

Wind Generation Impact on Symmetrical Fault Level at Grid Buses

“…The analysis of network strength at the point of WTGs connection (PCC) and a comparison of WTGs to support the AC network are discussed in [11]; the system modeling is very simple where the grid at PCC is represented as infinite bus. [12] provides an investigation of a case study network (small grid) concerning short circuit analysis among other processes with and without DGs using Matlab program; a maximum increase of 75.25% in FL has been recorded when DGs are placed in certain buses. In [13], the FL contributions of different WTGs for faults at the terminal of the generator where simulated using simplified model to determine FL characteristics for symmetrical faults.…”

Transient Stability Simulation of 33 kV Power Grid

“…Voltage stability is related to change in the load. This stability is the ability of a power system to maintain steady voltages at all busses from a given initial condition after being subjected to a disturbance [6]. Voltage instability increases by load demand or change in system condition which cause the incontrollable drop in voltage.…”

“…With abnormal low voltage it is lead to voltage collapse also contributes to blackout of the grid system [2]. The problems were reported with power flow and contingency in terms of blackout after main grid supply outages with overload and high fault current on distribution system [4] [6]. Critical clearing time is known as maximum time duration that a fault may occurs in a power system without loss of stability.…”