The distribution network is the final link in the power system, traditionally responsible for distributing electrical energy. However, with the widespread integration of distributed renewable energy sources, the emergence of diverse loads such as electric vehicles, and the advancement of the electricity market, the operating model of the distribution network is undergoing profound changes. It is evolving from a traditional endpoint distribution network to a modern distribution network capable of source-grid-load-storage interaction. This transformation is not only reflected in the changes in power flow patterns but also in the integration of power flow, information flow, and business flow.
Changes in Distribution Network Operation
Impact of Distributed Renewable Energy
The rapid development of distributed photovoltaics (PV) has significantly altered the traditional operating patterns of the power system. Firstly, with the increased penetration of distributed PV, a substantial amount of electrical energy is being fed back into the grid, causing reverse overloads in local areas, low-voltage lines, and even main transformers at system substations. Secondly, the development of distributed PV and controllable loads such as charging stations has changed the load characteristics of the power system, increasing the volatility, intermittency, and randomness of renewable energy generation. These changes significantly heighten the difficulty of grid regulation. Lastly, the extensive use of distributed PV, charging stations, and frequency conversion equipment presents higher demands on the power quality and safe, stable operation of the distribution network.
The Role of Energy Storage in Regulation and Support
Energy storage, as a crucial regulatory resource, plays a key role in the adjustment and support of the distribution network. It is a major component for adapting to the new forms of distribution networks. Specifically, energy storage plays an important role in the following areas:
Addressing the Challenges of Distributed Renewable Energy Integration
1. Industrial and Commercial User-Side Energy Storage: Utilizing the peak-shaving and valley-filling capabilities.
2. Distributed Energy Storage at Distribution Network Nodes: Integrating energy storage at local substations and switching stations.
3. Grid-Side Energy Storage: Installing energy storage at substations in load centers.
4. New Business Models: Exploring microgrids and integrated photovoltaic-storage systems to facilitate the efficient local absorption of distributed renewable energy, thus reducing the impact on the distribution network.
Enhancing the Adjustability and Flexibility of the Distribution Network
With the integration of distributed renewable energy and controllable loads like charging stations, the demand for regulation within the distribution network has surged, and the volatility of loads over both short and long periods has increased. Energy storage, with its flexible regulation capabilities, can achieve friendly interaction and efficient operation between sources, grids, loads, and storage. In regions with tight power supply capacities, constructing integrated solar-storage-charging projects can ensure that charging stations charge the storage system when idle and discharge stored energy to fill gaps when charging electric vehicles. Additionally, as electric vehicles become more prevalent, they can play a regulatory role in the distribution network through Vehicle-to-Grid (V2G) technology.
Providing Operational Reliability for the Distribution Network
Energy storage systems have millisecond-level rapid response capabilities, providing quick support during voltage and frequency drops in the distribution network, thus enhancing the reliability of power supply. Furthermore, energy storage can operate in voltage source mode and support transient stability, strengthening the robustness of the distribution network.
Participating in the Electricity Market and Providing Ancillary Services
With the progression of the electricity market and the gradual establishment of market and profit mechanisms, future user-side energy storage systems can, under suitable measurement and dispatch conditions, participate independently in the electricity market. They can also offer ancillary services such as peak shaving, frequency regulation, and voltage regulation through virtual power plants, thereby supporting the distribution network.
Future Development of Distribution Networks
Energy storage is a key technology for achieving the flexible, intelligent, and digital transformation of distribution networks. By integrating with large-scale distributed renewable energy sources and controllable loads such as charging stations, a distribution network capable of source-grid-load-storage interaction can be built. This will effectively promote the absorption of renewable energy and the efficient allocation of resources. This integration not only improves the overall efficiency and reliability of the power system but also lays a solid foundation for optimizing future energy structures and ensuring the healthy development of the electricity market.
In conclusion, the distribution network is transitioning from a traditional power distribution role to a modern, multifunctional power system hub. The application of energy storage technology will play an indispensable role in this transformation, driving the distribution network towards a more intelligent, efficient, and sustainable future.