PCC Circuit for Fast Local Control in AC-Coupled DERs
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Solution Overview
Problem
Existing energy management systems (EMS) in distributed energy resource (DER) systems face challenges with communication latency, which limits the speed of power flow control, and reliance on EMS for all power flow control, making the system vulnerable to failures and communication issues.
Innovation Solution
The implementation of a power output control and compensation (PCC) circuit within the power conversion system (PCS) of a DER system, which includes a current sensing device, a relay, and a processor to independently control power flow between a photovoltaic (PV) system and an electrical panel or load, reducing reliance on EMS for real-time power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If EMS is used for power flow control, then centralized coordination is achieved, but communication latency limits control speed
Solution Approach 1:
The patent segments the power flow control function by introducing a local controller at the electrical panel that operates independently from the central EMS. This local controller handles real-time power flow management between DERs and loads, while the EMS maintains high-level coordination. The segmentation eliminates communication latency bottlenecks for time-critical control operations.
Solution Approach 2:
The local controller acts as an intermediary between the EMS and the electrical panel/DERs. It receives setpoint commands from the EMS and executes local power flow control, bridging the gap between centralized coordination and distributed execution. This intermediary layer enables fast local response while maintaining centralized oversight.
2Extent of automation
If EMS controls all DERs, then system-wide power management is achieved, but system vulnerability to failures increases
Solution Approach 1:
The control architecture is segmented into independent layers: the local controller at the panel level and the central EMS. Each layer can operate autonomously, providing functional independence. If the EMS fails, the local controller continues to manage power flow based on local conditions, maintaining system reliability.
Solution Approach 2:
The system changes the operational parameters of control by enabling the local controller to autonomously adjust power flow based on real-time local conditions (DER output, load demand, electrical panel status). This parameter autonomy at the local level reduces dependency on continuous EMS communication, improving reliability during EMS outages.
3Speed
If local PCC circuit is implemented, then control speed increases, but device complexity increases
Solution Approach 1:
The local controller is designed as a multi-functional device that performs multiple tasks: monitoring DER output, measuring load demand, managing power flow, and providing backup control if EMS fails. By consolidating these functions into a single universal controller at the electrical panel, the patent avoids the need for separate dedicated devices for each function, thereby limiting the increase in overall system complexity.
4Reliability
If distributed control is implemented, then system reliability improves, but coordination difficulty increases
Solution Approach 1:
The control hierarchy is segmented into two distinct levels with clearly defined responsibilities. The local controller handles real-time distributed control for reliability, while the EMS handles strategic coordination. This segmentation of control functions simplifies the coordination problem by separating time-critical local decisions from longer-term system-wide coordination.
Solution Approach 2:
The system implements beforehand cushioning by providing the local controller with autonomous control capabilities that serve as a backup if EMS coordination fails. This prior preparation ensures that distributed control can maintain system reliability even when coordination becomes difficult or impossible due to communication failures.
Data Source
AI summary
A power output control and compensation (PCC) circuit operates within a distributed energy resource (DER) system. The PCC circuit is located in a battery power conversion system (PCS) and includes an input terminal to connect with a power source and an output terminal to connect with an electrical panel or load. A current sensing device is coupled between the input and the output terminals to measure a power level of the power source. A relay is coupled between the current sensing device and the output terminal and a processor selectively connects power from the power source to the electrical panel or the load based on the measured power level or based on other power measurements within the DER system. PCS-control of multiple power sources decreases cycle times for controlling distributed energy resources.