Transient Stability Analysis of a Multi-Machine Power System Integrated with Renewables

Abstract

The impact on the stability of power systems is rising as the penetration level of renewable energy with sporadic natures rises rapidly on the grid. However, the impact of different types of renewable energy sources (wind, solar) and their combination on system stability varies even with the same penetration level. This paper concentrates mainly on the stability analysis of multi-machine systems connected to various types of renewable energy sources. The study presents a simple and novel control technique named automatic reactive power support (ARS) for both single and combinations of renewable sources by injecting the available reactive power into the system during fault through converters to enhance system stability. The permanent magnet synchronous generator (PMSG) and doubly fed induction generator (DFIG) are both considered as wind generators in this paper for comparison. In addition, transient stability enhancement is carried out by improving critical clearing time of a three-phase fault in the power system. With the creation of a 3-phase fault at various buses, stability analysis is carried out on the 9-bus WSCC test bus system and also on the 68-bus IEEE test system. Comparative analysis of six test case conditions is provided and the considered cases are without renewable source, with DFIG as a wind generator, PMSG as a wind generator, solar PV farm, wind farm with DFIG and solar PV in combination and the combination of wind farm with PMSG and solar PV. Moreover, the improvement in critical clearing time of the system is compared using conventional and proposed controls with all the aforementioned renewable sources. Comparative results show that the proposed control technique improves system stability and also that the combination of renewable energy sources ought to enhance the critical clearing time of system.

A Novel Approach to Using Dual-Field Excited Synchronous Generators as Wind Power Generators

“…When the DESG is used as a wind generator, both the turbine and rotor parts will be included in the mathematical model to represent the dynamics of motion. This representation is derived from [34,35], considering the two-mass model (combining both generator and turbine).…”

“…A WSCC nine-bus, three-machine system, shown in Figure 15, connected with wind power generation at bus 8, is the multi-machine system considered for the stability analysis, and a DESG is used as a wind power generator. The mathematical models of the complete power system and DFIG are considered from [34,35]. A mathematical model of the DESG is presented in Section 2.1.…”

“…The extraction of the maximum power and reactive power control is achieved by controlling the field currents of the DESG in [32,33]. The stability of the power system is improved by modifying the rotor-side converter controller of the DFIG with the use of the post-disturbance terminal bus frequency of the DFIG in [34], and the same is achieved in [35] by supplying the reactive power through the grid-side converter during the fault period, with the adjustment of the real power supply.…”

A hybrid DMO-RERNN based UPFC controller for transient stability analysis in grid connected wind-diesel-PV hybrid system

“…Agarala et al [32] have realized simple and innovative control system called automatic reactive power support (ARS) for single and combined renewable sources to improve system stability. Permanent Magnet Synchronous Generator (PMSG) and Doubly Fed Induction Generator (DFIG) were deemed from wind generators in this paper for comparison.…”

A General Equivalent Modeling Method for DFIG Wind Farms Based on Data-Driven Modeling

“…Increasing the penetration of large-scale wind farms (WFs), wind power has become an important power source in power systems [1,2]. Wind power has randomness and volatility, which brings deep changes in the operation mechanism [3][4][5]. To support rapid development and reduce the operation risks, simulation technology is increasingly indispensable to reflect the behavior of the actual power systems and lead scientific construction of new-type electric power systems.…”