Solving the Problem of High Costs in Retrofit Projects for Aging Power Plants

In recent years, the stock market for photovoltaics has become enormous, with rapid iterations in system efficiency, decreasing system costs, and swift technological advancements, creating opportunities for technological upgrades. Especially after the photovoltaic industry achieved grid parity, the hidden value of existing power plants has increased significantly. The technological transformation of photovoltaic power plants involves integrating the Internet of Things, cloud computing, big data, artificial intelligence, new materials, and new technologies deeply with the photovoltaic power generation industry, transforming low-performance power plants into new intelligent photovoltaic power plants. However, to achieve this, several practical issues need to be considered.

1. Difficulties in Wired Communication Construction

During the initial construction of photovoltaic power plants, power cables and communication cables (optical fibers) are usually laid and buried together. Some older power plants did not lay communication cables during construction, requiring secondary construction for intelligent transformation. Excavation and similar operations can easily damage the existing power cables, causing personal injury or property damage.

2. High Construction Costs

   The construction costs for retrofitting photovoltaic power plants are also high. According to statistics, a 30MW photovoltaic power plant requires 6,300 meters of optical cable and 3,000 meters of cable trench. Additionally, there are circuit pre-settings, equipment commissioning, etc., leading to significant labor cost losses.

3. Poor Wireless Communication

There are many wireless communication solutions, but few practical application cases, mainly due to the following factors:

Short Transmission Distance: On-site equipment is beyond the wireless transmission range, preventing the equipment information from reaching the control room.

Limited Transmission Types: Some sites are in remote areas with no 2G/4G signal, hindering the adoption of DTU transmission solutions.

Environmental Interference: When the wireless transmission antenna is built into the combiner box, the combiner box and photovoltaic panels can block the wireless signal, preventing equipment information from being transmitted. Placing the antenna high up poses a risk of lightning strikes. Additionally, issues like harmonics generated by inverters can also interfere with wireless communication.

Increased Costs: Implementing wireless transmission necessitates antennas and communication modules, resulting in a cost that is approximately 100 higher for combiner box monitoring modules with wireless functionality compared to standard ones

4. New Solution

The FR-DCMG-MMPL power line carrier communication product is mainly used in DC transmission and distribution scenarios, such as photovoltaic combiner boxes, DC cabinets, telecom rooms, and communication base stations. It collects node data through power line carriers and communicates with the host computer via RS485. Its main functions include real-time monitoring of branch currents, bus voltage, box temperature, lightning arrester status, and DC circuit breaker status in the DC system, with capabilities for automatic alarm in abnormal states.

Power Line Carrier Communication Module: By using the power line carrier expansion module DC-DCMG-PLCx, communication with up to 24 nodes can be achieved.

Monitoring Function: Real-time monitoring of the combiner box’s power generation current, voltage, temperature, the status of lightning arresters in each PV string in the combiner box, DC circuit breaker status, and DC arc fault status.

isplay Content: Data such as detected voltage, current, temperature, and power generation can be displayed in a bar graph interface on an LCD, providing a more intuitive reading of current and other data.

5. Engineering Case Studies

Zhengtai 10MW PLC Combiner Box Communication Case

Gansu Hongyuan 5MW Old Power Station Technical Reform Case