Six DC Power System Features That Reduce 4G Network Energy Use
Wireless operators spend billions on energy to keep their 4G/LTE networks running. Rising energy costs, along with increasing numbers of 4G base stations being deployed in response to growing network demands, have carriers scrambling to find solutions that will bring down their operating expenses (OPEX).
Wireless operators spend billions on energy to keep their 4G/LTE networks running. Rising energy costs, along with increasing numbers of 4G base stations being deployed in response to growing network demands, have carriers scrambling to find solutions that will bring down their operating expenses (OPEX).
Fortunately, recent industry-wide technology developments in high efficiency and hybrid power management have paved the way for DC power systems with advanced functionality that enable carriers to conserve energy and spend less.
Six key technological characteristics of the latest DC power systems have emerged from these developments that operators should look for to reduce energy usage, bring down both hard and soft costs and optimize total cost of operation.
High AC-DC Power Conversion Efficiency
Newer AC-DC power conversion systems have raised the bar on rectifier efficiency levels. Previous generations set the industry standard at 92 percent efficiency, but the most recent state-of-the-art AC-DC power systems have brought about efficiency levels exceeding 96 percent.
Even a 4 percent difference can be much more impactful than one might suspect. The higher efficiency levels can actually cut power losses in half. And when such improvements in power efficiency are calculated across an operator’s entire network, the monetary savings can add up to millions of dollars per year.
For example, one advantage of high efficiency rectifiers is a reduction in the amount of air conditioning needed to keep the equipment cabinet cool. The higher the system efficiency, the less AC input power is required for DC output power conversion. This means less power is lost in the form of heat, so the air conditioner doesn’t have to work as hard to maintain a constant temperature. In fact, operators could choose to install a lower cost, less powerful A/C system. The benefits? More cost savings for the carrier.
Intelligent System Monitoring
Site monitoring and maintenance is another operating expense factor that should be considered. Innovative controller technology can save carriers thousands of dollars through remote system diagnosis, which helps decrease system downtime, and reduces both routine and alarm-generated maintenance visits.
Legacy controllers may offer system configuration, alarms and set up, but today’s more advanced systems, with intelligent web-based monitoring technology, can automate the simultaneous response management of hundreds of base station systems from the home office. Not only does this feature give carriers a real-time overview of power system health by showing readings, alarms, warnings and online/offline status, it also initiates automatic responses that eliminate the need for maintenance staff to travel to the site for resolution.
Example 1: Offsite monitoring enables battery back-up management from afar. High-accuracy battery sensors measure readings such as voltage, current and temperature. When certain environmental conditions, such as extreme heat or cold are detected, the system initiates an automated response that helps sustain battery health. The problem is solved without human intervention.
Example 2: The ability to run a diesel generator in cyclic mode also requires specialized intelligence. Remote monitoring and control can reduce diesel consumption (in some cases by more than 50 percent), increase efficiency, and lessen maintenance needs as well.
Offsite monitoring enables carriers to capture and analyze more data, leading to better maintenance decisions that save money and ensure maximum uptime. Some systems can compare power source usage, such as how much green energy has been used versus grid power. This provides information that can lead to improved power system performance and can identify operating expense savings.
Carbon Footprint Reduction
Cutting power consumption and heat loss by utilizing high efficiency AC-DC systems leads to reductions in an operator’s carbon footprint. This creates significant soft cost value. Lessening their environmental impact helps carriers fulfill strategic corporate goals that promote green, socially responsible operations.
Support for Alternative Energy
Most traditional base stations rely on a hybrid combination of power sources including grid power, diesel, and battery backup. Their power systems typically do not include the ability to incorporate alternative forms of energy, such as wind or solar. Inclusion of wind or solar power into the mix requires the addition of special equipment with flexible technology that allows carriers to meet the varying design KPIs at each site.
In order to integrate solar energy into a legacy system, for example, the carrier must purchase and install a separate DC power system that includes not only a power shelf that can handle solar inverters, but also a smart controller that is able to switch between available power sources, to maintain the highest efficiency possible.
As costs march ever upward and wireless networks broaden their reach into remote areas, demand is growing for DC power systems that are already designed with built-in support to accommodate solar, wind and other types of alternative energy. While the use of wind power is still in its nascent phase, solar power is starting to prove itself.
Rather than being “nice to have,” such features are now becoming highly desirable, even mandatory. The installation of telecom power systems with advanced support technology will help operators reduce their OPEX as they move toward inclusion of low-cost alternative energy to supply their power.
Power Density
Building DC power systems with higher efficiency and less heat generation is now allowing manufacturers to shrink their systems to create a smaller footprint, deliver higher power density, and decrease costs.
In the late 1970s switch mode rectifier (SMR) technology was first introduced. It was revolutionary for its power density and efficiency improvements. A breakthrough in the 1990s occurred when metal oxide semiconductor field effect transistor (MOSFET) technology was combined with improved soft switching topologies and control solutions, to yield significantly higher switching frequency and partly lossless switching. This further improved power density and efficiency.
The technology has continued to evolve, and today, efficiencies of up to 96 percent have been reached. Such high efficiency enables components and complete systems to be smaller, with less heat shielding required, while power output is increased.
Not only do these advanced power-dense systems take up less space in valuable telecom cabinets, they give carriers extra room to install other necessary equipment, preventing the need for construction of additional storage and eliminating related expenditures.
Design for Reliability
Today’s DC power systems are designed for reliability and provide a longer mean time between failure (MTBF) than older systems. Best-in-class switch mode rectifier systems are compliant with the most stringent emissions and immunity standards, including IEC61000-6-5 (Immunity for Power Stations and Substations), and should achieve MTBF greater than 300,000 hours.
Such an MTBF figure predicts an 87 percent probability of the rectifier operating for five years without a failure. While this reliability is very high, a contemporary modular system with N+1 redundancy built into a power shelf can further increase reliability.
Beyond that, the smart controllers integrated within some new power systems permit rectifiers to be placed into sleep mode when not required for recharging batteries. This not only reduces energy consumption and costs, but also extends MTBF.
Some smart controllers offer a DC-powered air conditioning solution. In the event of a mains / generator failure during hot weather, the controller will kick the energy supply over from DC-power to back-up batteries, to continue cooling the cabinet interior. This prevents over-heating of all equipment, including the batteries. When outside air temperatures cool down and chilled air is no longer needed, the smart controller will shut down the air conditioning unit. Features such as this help protect batteries and other equipment, prolong MTBF, reduce replacement and maintenance costs, and increase system reliability.
In the foreseeable future, the cost of power and the demand for more wireless bandwidth will continue to rise, which places an even heavier burden on operators to provide a more cost effective and operationally efficient network infrastructure, one that includes the incorporation of innovative, energy saving power systems.
Advancements in the features and functionality of the latest DC power systems now available on the market can minimize the pinch of acquisition expenditures by providing substantial reductions in energy usage, extending equipment life, enabling significant OPEX savings and dramatically improving overall power system ROI.
