Projects:2019s1-182 Power System Inertia Modelling in a Renewable Energy and Battery Storage Based Microgrid

Abstract

This thesis talks about the power system inertia based on the SA Grid. We analyse the current status of the problem of SA power system, and learn from other countries project. By comparing with each other, we choose battery storage system to be the solutions of South Australia. In this thesis, we build a basic model of the grid, and analyse the change of conventional generators and renewable energy source, the different reaction of the voltage and current waveform, and the RoCoF of the system. After that, we model the real SA power grid. Finally, we can jump to the conclusion: battery storage system does improve the power system inertia.

Introduction

• Case 1: Brazil and Paraguay November 2009

When the Itaipu hydroelectric dam on the Paraguay-Brazil border suddenly stopped producing 17,000 megawatts of power, outages quickly spread through both countries. The key reason for the blackout is that the disturbance was triggered by the automatic disconnection of 765 kV transmission line whose inertia is less.

• Case 2: South Australia September 2016

In 2016, South Australia was hit with a strong storm that caused serious damage to the electricity transmission infrastructure leaving 1.7 million people without power. The key reason of the huge blackout is that there was significantly lower inertia in SA in the most recent event, due to a lower number of on-line synchronous generators. This resulted in a substantially faster rate of the change of frequency (RoCoF) compared to the other events, exceeding the ability of the under-frequency load shedding schemes (UFLS) to arrest the frequency fall before it dropped below 47 Hz.

Power system inertia in SA Grid

In South Australia, the power system inertia shows a steady decrease from 2013 to 2017

SA Power Grid Model

Figure of SA Power Grid Modelling by PowerFactory

Power System Inertia Study Based on a Simple Model

The power system inertia studies are taken on a simple power system model which includes one synchronous generator, two transformers, one wind farm, one PV farm, one battery storage system, one SVC, one synchronous condenser, one external grid and one load.

The frequency and RoCoF (rate of change of frequency) of the synchronous generator are monitored by the plotting data of them. The load is simulated increasing 20% up in active power and 10% up in reactive power. At the same time, the changing of frequency and RoCoF of the synchronous generator is recorded synchronously due to the changing of load.

A simple power system model by PowerFactory

Four cases are studied in this power system inertia studies.

• Case 1: basic no renewable energy
• Case 2: with lower renewable energy
• Case 3: with more renewable energy
• Case 4: with Battery Storage System

Comparison of Frequency change in 4 cases:

Comparison of RoCoF change in 4 cases:

Conclusions

• 1. Power system Inertia in SA is decreasing, and limited connection through Victoria, hence the system inertia has reduced and will reduce further.
• 2. SA Power network Model has been developed, which shows existing transmission grid, and current renewable energy generation options and flexible to integrates future results
• 3. Preliminary results have been given, it shows that generation demand variance has a significant impact on RoCoF

Selected References

• [1] South Australian Electricity Report, November 2018 AEMO
• [2] South Australian Renewable Energy Report 2017
• [3] A low carbon investment plan for South Australia. Planning report. Government of South Australia (2015, December).
• [4] Application of Energy Storage in High Penetration Renewable Energy System
• [5] Battery Storage Technologies, Applications and Trend in Renewable Energy

Members

  Qinghua Li
  Da Di

Supervisors

  Associate Professor Nesimi Ertugrul