Energy is largely viewed as the basic necessity for the economic development of a country. Many day-to-day functions in today’s modern society come to a halt when electricity supply is interrupted.
A distribution transformer is an electrical component that lowers the medium voltage it receives to low voltage levels suitable for home or commercial use, which are typically 400V at three phase or 230V at single phase.
The low-voltage network is the final stage of power distribution that is connected directly to the ordinary low voltage consumers. It is the ‘last mile’ of electricity transmission which carries electric energy from distribution transformers to the electricity meters of industrial, commercial, and residential customers. This is the stage where suppliers can disperse a wide range of small-scale loads of electricity networks to their customers.
There is little known knowledge among consumers on the low-voltage network and how it affects their daily lives. Let’s explore the basics of low-voltage networks in Malaysia including the design, its maintenance and future.
Considerations for building low-voltage networks
In an interview with Energy Watch TNB Distribution Network Division shared, “Distribution of power takes into consideration multiple aspects – consumers load demand, distance from consumers, safety features, and the topology of an area which factors in the geographic features of a location.”
“Low voltage is distributed to customers through overhead lines, underground cables or a mixture of both configurations. In rural areas, low-voltage networks tend to be overhead, while in urban areas they are more likely to be underground,” they continued.
Underground systems do offer a few advantages – namely, protection against storms, avoiding tree branch falls, or other accidents and exposure risks. However, underground lines require ground excavation, and may prove difficult and costly in certain geographies. In addition, it usually takes longer hour to detect and restore electricity supply to consumers if the underground line is faulted.
The team also shared that for residential developments, these network lines tend to be overhead systems, but upon the property developer or local authority’s request, it may be designed as an underground system at cost.
While power distribution companies may have visibility over its high and medium-voltage networks, they typically do not have the same level of visibility on low-voltage networks. Additionally, low-voltage network operators must contend with voltage control issues – any miscalculation or system malfunction could impact the delivery of power supply to consumers’ homes.
To help distribution teams manage the network more carefully, innovations like Intranet-Based Load Management System (ILMAS), online readers and state-of-the-art substations are deployed by utilities. The ILMAS tool, for example, stores and provide analyzed report of low-voltage load reading data from data loggers for operators to take necessary action.
Other innovations include adoption of Geospatial Information Systems (GIS), to effectively manage asset data and to enhance operation efficiency with exact knowledge of the asset position and network information.
According to the Distribution Network Team, GIS technology is already available in certain areas in Klang Valley, such as Cheras, Putrajaya, Cyberjaya, Kuala Selangor, Sungai Besar, Banting and Sepang. “Nationwide low-voltage network connectivity GIS data is expected to be completed by 2024,” they stated.
GIS data management activities are divided into two categories:
- Medium Voltage (MV) data – comprised of medium voltage assets, network, and customers from 6.6kV up to 33kV
- Low Voltage (LV) data – comprised of low voltage assets, network, and customer meters
To accelerate the low voltage data production activities, GIS has embarked on mobile mapping technology since 2020 for data collection activities. This technology capture 360-degree panoramic images of TNB’s asset. The data collection at low voltage level involves capturing panoramic images with coordinates of electric asset like poles, feeder pillars, streetlights, conductors, and customer meters. The images and light detection and ranging (LiDAR) data captured from the mobile mapping will be processed and extracted in order to pin down Distribution Network’s assets on digital map. GIS data will support the establishment of TNB’s Smart Utility framework and with the ability to map the source of supply for TNB customers in geographical format will further enhance Distribution Network’s business operation in future.
The challenge of renewable integration
Integration of renewable energy into the grid is another challenge low-voltage network operators must contend with. In Malaysia, the government has announced a net-zero carbon aspiration to be achieved by 2050, which includes higher incorporation of renewables into the country’s grid.
Currently, the national Feed-in-tariff and Net Energy Metering mechanisms allow participants to generate their own power through clean technologies such as solar panels, and sell it back to the grid. However, the infusion of renewables requires significant planning and proper system readiness – otherwise it risks damaging existing infrastructure and causing blackouts.
Integration of renewable energy into the grid is another challenge low-voltage network operators must contend with
“Solar is an intermittent generator as it is not able to produce stable energy due to weather changes. This intermittency generation may cause instability to the network, most common is the voltage rise beyond the normal level. To ensure voltage stability, the company will need to deploy new technologies such as battery storages, or to invest in distribution transformer with on load tap changer to vary the voltage, ensuring voltage stability is achieved in the grid. Currently, this technology is under study,” said TNB Distribution Network Division.
“For the actual solar photovoltaic (PV) installation, it must be equipped with smart inverter features. Smart inverters are an emerging technology that can help integrate solar energy and other distributed energy resources (DERs) into the electric grid,” the Team continued.
Inverters are components that convert direct current (DC) electricity, which is what a solar panel generates, to alternating current (AC) electricity. But unlike normal inverters, ‘smart’ inverters can communicate with the grid and make autonomous decisions with its advanced infrastructure – making it a more sophisticated version of the device.
“Like traditional inverters, smart inverters convert the DC output of solar panels into the AC that can be used by consumers in their homes and businesses. Smart inverters go beyond this basic function to provide grid support functions, such as voltage regulation, frequency support, and ride-through capabilities,” they added.
With greater incorporation of renewables, there will also be greater incorporation of battery storage systems. Batteries help store renewable power and deliver it at a later time – a necessary feature since renewable sources like sunlight and wind are irregular by nature.
From the low-voltage network perspective, there is a need for battery storage energy systems (BESS) to comply with connection requirements stated in national standards. “BESS converters operate bidirectionally – via charging and discharging. In the event of TNB’s supply failure, the consumer has to ensure that there shall not be any reverse power/back feed from any internal source of generation (example solar PV, battery, or generator) to the TNB grid,” said the division.
High-load technologies and trends
Another key development in the energy consumer space is electric vehicles (EV). “Unlike normal loads, EVs are nonlinear and deliver dynamic loads which may scatter across the power system. The interconnection of a large fleet of EV to the power grid will expose risks to the power grid reliability and supply quality,” shared TNB Distribution Network Division.
EVs are also relatively large power consumers in terms of charging load, especially for fast charging systems which can absorb 240 kW of power or more. The division added, “Large-scale rollout of EV charging will significantly increase the power grid load demand; this is especially critical during on-peak hours of the power grid. On top of that, EV users tend to charge their vehicle simultaneously during the evening hour (after office hours).
Backbone of the nation’s power supply
Low-voltage networks make up an essential part of that – helping deliver power safely and effectively to consumers.
As of 2022, Malaysia’s national grid connected more than 472 major substations to 25,000 cct-km of transmission lines, linking everything into one single delivery system. Low-voltage networks make up an essential part of that – helping deliver power safely and effectively to consumers.
Innovations in power electronics and technology will help distribution companies better manage power supply to multiple customers across the country. As distribution-stage consumer technologies such as EVs and solar panels continue to gain traction, there will be a progressive need for low-voltage networks to integrate new components to improve grid reliability and safety.
Tools like smart meters will also help provide distribution companies with information on voltage quality and outage alerts – helping to improve the overall service and supply through the low-voltage network.
With continuous innovation from both demand-side and supply-side technologies, modern society can continue to safely rely on a stable and resilient power delivery system.