With more functions and capabilities, microgrids are not only providing energy to remote areas most in need of power – but they are also playing a supporting role in the energy transition. They offer value and reliability while reducing carbon emissions, diversifying energy resources, and cutting costs. The microgrids of the past have gradually evolved into smart microgrids, achieving revolutionary breakthroughs in control theory and technology.
Smart microgrids are distributed energy resource (DER) power systems with the complete range of functions – generation, transmission, and distribution – to ensure safe consumption of energy on the user side. Working as distributed generation systems, they can improve the energy utilization rate of terminals through power scheduling with advanced information and communications technology (ICT).
Newer smart microgrids have at least two significant advantages. First, they are intelligent on the power generation side – monitoring and controlling the power generation of internal DERs, and balancing inbound power from utility grids and internal storage devices based on total loads in real-time. Second, they are intelligent on the power consumption side. With centralized controls and the utilization of distributed energy resource management systems (DERMS), today’s microgrids are now able to control power balance, optimize system operation, carry out fault detection and protection, and manage power quality.
TBEA’s smart microgrid R&D
Huang Lang, senior R&D scientist at TBEA Electric, has focused on smart microgrid technologies for more than 10 years. He recently met with pv magazine to discuss the history of TBEA’s advancements in microgrids over the years.
TBEA began exploring microgrids in 2014. And at an early stage, it researched power electronics transformer technologies, which are essential to power grids, as it continued to build on its already established track record with high-voltage electrical equipment. In 2015, the company joined a national Chinese R&D initiative (the 863 Program) focused on bidirectional inverters. Later in 2016, after significant investment and R&D, TBEA launched its core equipment for microgrids – the power router. This has been a significant technological development for smart microgrids.
“From 2014 to 2018, we only did R&D work in our laboratory of TBEA’s New Energy Research Institute. But in 2019, based on deep business analysis, TBEA’s management team saw the opportunity for microgrids reaching its turning point for marketization,” said Huang Lang. “And we thus separated the microgrid department from the research institute and built up the product line.”
“The unique characteristic of TBEA’s microgrid solution lies in the principle of microgrid as a service, or ‘MGaaS’. We provide an integrated energy system led by our core technical equipment, the multi-port power router, which is supported by TBEA’s DERMS solution and modular energy storage system,” said Lang. “The purpose of our system is to solve the most concerning challenges for customers, such as large energy consumption with cost reduction potential, high electricity quality requirements for electricity quality, and those with high electricity prices but low energy efficiency.”
TBEA’s microgrid system solution is comprised of three core products.
The company invented its power router in 2016, and has a specially designed module that integrates internal communications, power electronics conversion, advanced system controls, artificial intelligence, and other technologies for intelligent routing in a local power grids to efficiently use primary and secondary distributed energy. Its latest version has intelligent redundancy based on modular LPHS topology, with a low-loss system design based on silicon carbide devices, and online cluster efficiency optimization. TBEA says all of these advanced smart technologies provide the product with higher reliability and efficiency. Differing from historic traditional solutions of dispersed inverters, energy storage converters, gateway cabinets, and central controllers, the TBEA power router solution integrates primary and secondary equipment to improve the power efficiency.
TBEA’s Energy Management System (TEMS)
If the power router is considered the heart of the microgrid, then TBEA’s energy management system (TEMS) can be treated as the brain for the grid – controlling the entire system.
For power generation of the microgrid, comprised primarily of DERs – such as solar PV, wind, and even fuel cells – TEMS controls the output of these distributed power sources according to the specified voltage and frequency. TEMS supports the overall control strategy of the microgrid system and a scheduled dispatchment can be made and predicted according to the output of all major power sources.
For widely adopted energy storage systems used in microgrids, connected via inverters, TEMS sends instructions to determine operational functions and power generation. When the microgrid is connected to a utility grid, the storage system can ensure the stable output of the distributed power supply and assist with peak-shaving when at full electric load capacity. When disconnected from the main grid, the energy storage system focuses on maintaining the system stability and reducing power fluctuations for end users.
In terms of grid loads, the TEMS solution controls and predicts multiple power loads. The loads of the microgrid is managed in two stages – key loads and controllable loads. The key loads are given priority and protected with consistent power supply, while controllable loads can be cut off from the system in emergency situations. The company solution is able to react quickly according to the situation.
According to Lang, the TEMS solution provides “panoramic perception, real-time data collection, online monitoring, and accurate prediction abilities.” With self-correcting multi-algorithm support, the company says it can predictively support multiple time duration forecasts, including zero to four hours, zero to 24 hours and zero to 168 hours, with more than 90% accuracy. To improve power quality, it is able to support frequency curtailment and self-adjust voltage requirements. The system is also able to optimize according to electricity prices by most effectively using internal transactions, trading, and the external utility grid. “We have an example in an industrial park grid, where the average power cost dropped by 30% with this TEMS installed,” Lang noted proudly.
TBEA’s smart inverter is the final core element for the company’s smartgrid solution – which helps to maximize the efficiency of storage. TBEA’s latest high-voltage inverter offering, scheduled to launch in the second half of 2020, is designed for 1.5 MW of capacity, and fit for 1,500 V battery systems. The company says that its design will improve the energy density of the entire system comprehensively, in order to effectively reduce the costs of power consumption.
TBEA currently has several smartgrid demonstration projects now running that are proving the advantages of the company’s new solution. The TBEA Xi’an Industrial Park microgrid demonstration project was completed in 2019 and is functioning smoothly. This 863 Program-backed project consists of a 2.14 MW rooftop PV system, a 1 MWh lithium iron phosphate (LFP) battery storage system, and charging piles of 960 kW. Compared with traditional solar+storage projects, the company says that it records a 28% increase in total generation, and a 60% reduction in operation costs, with the smart energy management system.
Another field study, the Dongguan Songshan Lake Integrated Energy Project, is backed by China Southern Power Grid. For this site, TBEA provided a 2 MW power router system and fulfilled complicated connection requirements, with four different AC and DC voltage levels – including 10kV AC, 10kV DC, 380V AC and ± 375V DC. The company says it is now providing reliable power supplies for the Dongguan Easy Data Center and other loads. TBEA has worked with national grids and state-owned energy companies on other microgrid projects “in which the reliability, stability and economic factors of the smartgrid system have been continuously verified,” said Lang.
Future of smartgrids
TBEA says it will continue to explore and expand its microgrid technology for business applications such as industrial and commercial parks, data centers, islands, and areas without electricity. It will continue to optimize its algorithms and products. Looking ahead, it aims to provide more advanced smartgrid solutions.
As an experienced electricity researcher and microgrid scientist, Huang shared his thoughts about future trends for power systems: “In the future, low carbonization, digitization, and decentralization will be the mainstream of the world’s energy pattern.” He adds that power systems will gradually incorporate the trends of comprehensive power electronics, cluster nestification, and system digitization. “The flexible soft-switching based on power electronics’ transformer topology, the honeycomb active distribution network based on multi-port power routers, and the energy routing technology backed by power routers will become the core of the future of microgrids,” he says.