Novel fast and secure approach for reverse power protection in synchronous generators

Abstract

The purpose of the reverse power (RP) protection is essentially to prevent severe damage to the generator prime mover. For this aim, directional relays are usually utilised. RP condition (RPC) leads to initial oscillations of power and frequency which might exceed the RP threshold and lead to mal-operation of the relay. Therefore, assigning a time delay is essential to reduce the oscillations. However, this strategy increases the relay trip time, which leads to enhancing the motoring time and the risk of damage to the prime mover. This study proposes a novel algorithm to detect RPC in synchronous generators, based on some easily accessible quantities including active power (P), load angle (δ), internal voltage (E A), terminal voltage (V) and the phase difference between voltage and current (θ). This scheme utilises two criterions including the sign of θ and also comparing V with tangential component of E A on V (E A Cosδ). This algorithm is independent of the size and type of load and is also capable of discriminating RPC with other potential faults. The performance of the proposed approach has been verified with Matlab software and the obtained simulation results show the fastest operation and highest reliability of the proposed technique compared to others.

Preventive protection of marine electrical power system from the transition of generating sets to motoring mode

“…Let us consider the method of protecting the GS from the transition to the motoring mode, which is widely used by companies across the world. According to this method, the reverse power value is used as a diagnostic indicator [9,10]. One of the operating GSs might fail, for example, in case of a failure of the fuel supply system to the diesel engine.…”

“…One of the areas for such projects is developing methods that ensure the timely shutdown of the GS when it switches to motoring mode due to drive motor failure [9,11]. According to researches [9,10], the formation of cutoff signal for the GS during transition to motoring mode can lead to serious primary motor damage if done with a time delay. In order to solve the issue, unique algorithms are suggested.…”

Fast and Secure Angular-Based Detection Algorithm for Reverse Power Occurrence in Synchronous Generators

“…As a result, this issue is considered as the main drawback of this method. Another study [8], which was presented by the authors, detects RPC, using some electrical parameters on the basis of differences in over and under excitation modes in lagging and leading operation of synchronous motors and generators. The mentioned method improved the operation time of the relay in comparison with directional and flux-based methods.…”

“…But, the speed of operation and also the reliability and fault discrimination of this method can still be reinforced. It is noteworthy that, over the past years, all the investigations about RPP have been limited to [2][3][4][5][6][7][8]. On the other side, during the recent years various contributions have been presented for generator protection against possible faults such as loss of excitation (LOE) and out of step (OOS).…”

“…Besides, OOS is considered as another important protection which can be detected by P and δ on the basis of equal area criteria [19][20][21][22][23][24]. So, the suitable operation of the aforementioned techniques in detection of various potential faults and also better performance of parameter-based RPR [8] in comparison with conventional directional methods in synchronous generators becomes the most significant motivation for the authors to present a new technique for generator RPP in order to enhance the accuracy and also improve the speed of the previous introduced schemes.…”