AEL-LPSG Low Power Synchronous Generators Application

The Low Power Synchronous Generators Application, "AEL-LPSG", has been designed to study the procedure and the maneuvers requiredfor the synchronization of synchronous generators with the grid, with the aim of delivering the generated energy as done in actual powerplants.

The "AEL-LPSG" application allows the user to go deeper into the working principles and control of synchronous generators to show thestep-by-step synchronization process with the electrical grid. For this, the application includes a synchronous generator coupled to a motor(which will act as driving force, simulating a turbine) along with a series of modulessuch as a single-phase transformer, an AC/DC converter and a voltage regulatorwhich form the generator excitation circuit. It is also included a motor controller forthe turbine-generator speed control, an analog overcurrent relay as grid protectiondevice and a network analyzer to monitor the generation electrical parameters suchas the active and reactive powers generated, frequency, voltage, current, powerfactor, etc.

This application offers two possibilities regarding the generation group control.The first option, the manual control of synchronousgenerators kit, includes a PWM signal generator module for the control of the synchronous generator excitation current (and thereforethe output voltage). This enables the user to carry out the no load, under load andshort circuit test aimed to obtain the characteristic curves and the equivalent circuitof the synchronous generator. This kit also includes a synchronization module whichwill allow the user to monitor and carry out manually the synchronization process.

For that, the synchronization module has two analog voltmeters (grid and generationvoltage), two frequency meters (grid and generator frequency), a digital synchroscopeand two push-buttons for closing and opening the synchronization switch.

The second option, the synchronous generator automatic control module, offers the possibility to control automatically every electricaland mechanical paremeter of the generator-turbine group. The most signifcantcontrol parameters are the turbine speed, the generator frequency, the excitationcurrent, the voltage at the generator output and the active, reactive and apparentpowers. Moreover, this control module is at the same time an advanced protectionfor generators and turbines. It meets the ANSI standards regarding the protectionparameters for generators and turbines (ANSI 81O, ANSI 81U, ANSI 59, ANSI 27,ANSI 50/51, ANSI 32R/F, ANSI IOP 32, ANSI MOP 32, ANSI 46, Voltage Asymmetry,Generator Ground Fault, Phase Rotation, ANSI IEC 255 , Generator Lagging Power Factor, among others). It is required to acquire at leastone of the two previously described options to be able to work with the modules included in the base unit.In order to acquire a greater experience with the study of synchronous generators, it is recommended to acquire a set of resistive andinductive loads with the aim of studying the island operation of synchronous generators (isolated from the national grid). These loads willallow the user to go deeper into the basic concepts about the behaviour of synchronous generators working under load, such as generationand demand in isolated systems, voltage drops or the output voltage control by means of the excitation current regulation.

It is also recommended to acquire a kit for the study of faults in synchronous generators, consisting of an advanced differential protectionrelay with configurable numerical programming which allows showing the features of three-phase differential protection, two power switchmodules as interrupting devices, a fault injection module for the injection of single-phase, two-phase or three-phase, to earth, faults anda module with three-phase inductances as buffering element for the faults at the generator induced side.

In addition, it is recommended as well a rotor protection module for the study of faults at the synchronous generator excitation side and athree-phase harmonic filter for the reduction of the harmonics resulting from the regulation of the generator excitation current.

The "AEL-LPSG" is one of the most complete and versatile applications regarding the in-depth study of synchronous generators, both inisland and parallel to grid operations. Furthermore, it is compatible with any type of energy transmission line which makes it possible tostudy the impact of synchronous generators on real grids, analysing events such as power transfer among several machines working inparallel, sudden decouplings and its consequences and endless meanuevers related to electric generators.

Finally, for the most optimal management of the application, it is recommended the Energy Manager and Data Acquisition Software,EMG-SCADA. This awesome tool allows the user to monitor all the curves for the grid and generator electrical parameters, watch thevoltage dips, energy losses in transmission lines and voltage drops. In addition, it allows saving all the acquired data to watch and compareit later. It is possible to see clearly and with accuracy the effects of reactive power compensation on the monitored power curves, maximumand minimum energy demand, load unbalances and the variation of the power factor in the nodes of the system.