On-line stator winding fault diagnosis in induction generators for renewable generation

Abstract

Abstract-Renewable generation systems are increasing its presence in electrical power systems. For this reason, it is more important than ever to count with reliable and secure generation systems. In this way, the use of on-line diagnostic techniques in the maintenance schemes can be useful. This paper is about on-line condition monitoring in induction generators for small hydro stations and wind farms. In particular, stator winding fault diagnosis is analyzed. Currently, there are diagnostic techniques that are used in induction motors, but they could be used in generators as well. This paper analyzes the induction generator characteristics and describes the appropriate diagnostic techniques. These techniques depend on the machine voltage. As most of the induction generators are low voltage machines, the diagnosis of stator winding faults will be based on the detection of inter-turn short circuits. Most of the inter-turn short circuit diagnostic techniques are noninvasive as they are based on voltage and line current monitoring.I. INTRODUCTION Renewable energy generation, particularly energy from wind, water, solar power and biomass is a central object of current energy policies. Renewable energy has an important role to play in reducing CO 2 emissions. It also helps to improve the security of energy supply by reducing the dependence on imported energy sources. Renewable energy sources are expected to be economically competitive with conventional energy sources in the medium to long term.Several types of electrical power generation sources are emerging with different degrees of development and future prospective but currently, wind generation is increasing its presence in an amazing way, due to several characteristics: the production has zero fuel cost, it is environmentally clean and the total energy production can be quite important. Hence, wind energy has turned out to be one of the most important and promising sources of renewable energy. The installed wind power increase expectations for the next few years are high. This energy source will represent a significant proportion of total installed power in the power system. Small hydro is a proven technology, which has now reached maturity. Ideal for electrification of remote sites, it also serves as a complement to national electrical production in the case of strong demand and consumption.Both wind and hydro systems convert renewable energy into mechanical energy first and into electrical energy afterwards. The electric generators can be either asynchronous or synchronous.

A brief status on condition monitoring and fault diagnosis in wind energy conversion systems

“…When scanning the available literature, it has been found that fault detection and diagnosis techniques are mainly arranged for inter-turn stator faults and stator or rotor asymmetries [20][21][22][23][24]. In all these works, authors are just applying wellestablished techniques to induction generators.…”

A Novel Approach for Detection of Shorted Turns Fault in Machine Using Combination of Flux and Instantaneous Power Signal

“…A combination of wavelet and power-spectral-density techniques for the detection of shorted turn faults in induction motors has been reported in [8]. Although, condition monitoring is normally done for induction motors [9], and it can also be carried out for induction generators as well [10].…”

“…Some of these factors are the rigidity of the foundation of the test motor and the accuracy of the shaft alignment. The motors must have a firm and rigid foundation to eliminate soft foot problems and to reduce vibration [10].…”

DFIG-based wind turbine fault diagnosis using a specific discrete wavelet transform

“…For small induction machines, the stator winding insulation degradation is one of the major causes [11], [21][22][23].…”