Projects:2021s1-13006 Weather Station Solar Powered Battery System Optimisation

Introduction

ElectraNet operates a number of weather stations across the state of South Australia, from Leigh Creek to Mount Gambier. These weather stations are solar powered and equipped with batteries, allowing them to operate in remote areas without an external power source. ElectraNet is looking to change the operating capabilities of the DC power system and to better optimise the power system. The operational requirements, sensor power budget and historic weather data will be used to guide the evaluation and design of the 12 V DC power system. This includes assessing the solar panel sizing and performance at different locations in the state, and under different operating conditions. The charger and battery performance will also be considered, with a focus on the impact of temperature on battery capacity over the planned life of the system. The enclosure design is also expected to contribute to the performance of the overall DC power system. The outcomes of the project will include a power budget, the design of the DC power system, and selection of components including the solar panel, charger, battery, and enclosure that meet the requirements of the weather sensor and remote terminal unit. The system lifecycle will also be evaluated, including the operability and maintainability of the system.

Project team

Project students

• Riley Bass
• Matthew Grear

Supervisors

• A/Prof Dr. Nesimi Ertugrul
• Dr. Gabriel Haines (ElectraNet)

Objectives

Develop a full design of a new and optimised PV and battery powered weather station that meets the following requirements:

1. The system is DC and completely off grid.
2. The battery must remain above 50% state of charge (SOC) for at least 7 days with minimal solar irradiance.
3. The battery must last at for least 5 years.
4. Preferred one design to fit all weather station locations.
5. The ability to accommodate future component upgrades.

Background

DC Solar Powered Weather Station Block Diagram

Dynamic Line Ratings

A cheap, consistent, and reliable flow of electricity is desired by all customers. It is the Transmission Network Service Providers (TNSP’s) duty is to continually discover, innovate and maintain ways to deliver these outcomes. In South Australia, TNSP ElectraNet have implemented Dynamic Line Ratings (DLR) throughout their Network.

Traditionally, Static Thermal Ratings have been used in transmission lines, to determine the amount of permissible current through the given line . Reality, however, suggests that the permissable amapacity of transmission lines are constantly changing, depending on various factors. Dynamic Line Ratings form a method to actively alter the ampacity current rating of transmission based on live weather data . Some of the varying factors contributing to the DLR are wind speed, wind direction, solar irradiation, and ambient temperature. In good cooling conditions (for example, low ambient temperature) DLR raises limits to allow higher current to pass through the relevant transmission line, and in hot conditions (for example high ambient temperature), DLR reduces the current limit on the line to prevent overloading issues. Figure 1 gives an example of how changes in weather conditions can change line capacities. In comparison to Static Ratings, DLR enables Transmission Networks to optimise grid usage, minimise grid congestion and capitalise on economic opportunities [1]. This is increasingly important, as the proportion of Non-Scheduled Generation (Solar PV and Wind) continues to rise, and more line capacity is needed at times to meet the output of these renewable energy sources.