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Communication Systems for Grid Integration of Renewable Energy Resources
F. Richard Yu, Peng Zhang, Weidong Xiao, Paul Choudhury
TL;DR
Intermittent renewable generation is difficult to integrate into the power grid, making communication systems important for accommodating distributed generation and managing renewable generators and power systems. The paper reviews available technologies, presents communication systems for Bear Mountain Wind Farm and photovoltaic systems, and outlines research challenges and possible solutions. Its supported conclusion is that hybrid communication technologies are used for renewable-energy grid integration, including supervisory control, data acquisition, power protection, and control.
Problem
Intermittent renewable sources make integrating renewable energy resources into power-grid infrastructure challenging.
Method
The paper reviews communication technologies and presents systems used in Bear Mountain Wind Farm and photovoltaic power systems, alongside research challenges and possible solutions.
Results
The paper documents a hybrid mix of communication technologies for renewable-energy grid integration, including systems for supervisory control and data acquisition, power protection, and control.
Takeaways & Limitations
Communication systems support the integration of distributed renewable generation and the monitoring, operation, and protection of renewable generators and power systems.
Abstract
from arXiv · showhide
There is growing interest in renewable energy around the world. Since most renewable sources are intermittent in nature, it is a challenging task to integrate renewable energy resources into the power grid infrastructure. In this grid integration, communication systems are crucial technologies, which enable the accommodation of distributed renewable energy generation and play extremely important role in monitoring, operating, and protecting both renewable energy generators and power systems. In this paper, we review some communication technologies available for grid integration of renewable energy resources. Then, we present the communication systems used in a real renewable energy project, Bear Mountain Wind Farm (BMW) in British Columbia, Canada. In addition, we present the communication systems used in Photovoltaic Power Systems (PPS). Finally, we outline some research challenges and possible solutions about the communication systems for grid integration of renewable energy resources.
I. INTRODUCTION
Intermittent renewable generation and distributed installation make grid integration challenging, increasing the need for communication systems that support monitoring, operation, and protection. The paper reviews communication options, examines wind and photovoltaic applications, and identifies research challenges.
- Intermittent renewable sources make integrating significant renewable generation into power-grid infrastructure challenging.
- Distributed renewable generators affect grid operation and require new grid infrastructure beyond the traditional centralized, one-way electricity model.
- Communication systems enable distributed generation and support monitoring, operation, protection, and network reconfiguration across grid equipment.
- Available communication options include fiber optics, copper-wire lines, power-line communications, and wireless technologies, with no settled standard of choice.
- Utilities must balance bandwidth, latency, reliability, security, scalability, and cost when operating multiple applications over communication networks.
- The paper reviews communication technologies, presents Bear Mountain Wind Farm and photovoltaic systems, and outlines research challenges and possible solutions.Bear Mountain Wind Farm uses thirty four ENERCON wind turbine generators with a generation capacity of 102 MW.
II. OVERVIEW OF COMMUNICATION SYSTEMS FOR GRID INTEGRATION OF RENEWABLE ENERGY
Grid-integration communication systems combine high-bandwidth backbone networks with lower-bandwidth access networks. The reviewed technologies include fiber, microwave, wired PLC, wireless systems, and related standards.
- Communication system architecture: Grid communication systems typically use a high-bandwidth backbone and lower-bandwidth access networks connecting facilities to the backbone.Fiber optics and digital microwave radio commonly serve as backbone technologies, while access networks may use copper, PLC, or wireless systems.
- Power line communications: Power line communications transport data over existing electrical wires and support applications including utility metering, control, and distributed energy generation.Newer PLC technologies can provide bit rates of up to 200 Mb/s.
- Power line communications: PLC standardization involves HomePlug, the Universal Powerline Association, HD-PLC, ITU-T G.hn/G.9960, IEEE P1901, and NIST-related specifications.ITU-T adopted G.hn/G.9960 for high-speed PLC, while IEEE P1901 develops medium-access-control and physical-layer specifications.
- Power line communications: PLC signals share unshielded power-line cables that can both generate and receive electromagnetic interference.This shared medium creates an operational limitation for PLC deployments.
- Power line communications: PLC modules are usually more expensive than wireless modules, while wireless communication can be more practical for battery-powered meters without power lines.The comparison is especially relevant to applications where no powered wiring is available.
B. Wireless Home (Local) Area Networks
Wireless local-area technologies such as ZigBee and Wi-Fi support energy-management and smart-meter communication, while cellular and WiMAX networks offer wider-area connectivity. Their utility use involves trade-offs in power consumption, cost, specialization, and deployment scale.
- Wireless Home (Local) Area Networks: ZigBee Smart Energy connects home-area-network devices with smart meters and other devices, enabling utilities to communicate directly with end consumers.The underlying home-area framework supports automated control of lighting, appliances, and other household devices.
- Wireless Home (Local) Area Networks: Wi-Fi provides high data rates but requires careful consideration of power consumption when used in utilities.Its widespread use in laptops and phones does not remove this utility-specific constraint.
- Wide-area wireless networks: Public cellular networks can reduce costs by leveraging existing networks and telecommunications expertise, but may not meet all utility requirements because they are not specialized for machine-to-machine applications.The relevant trade-off is between infrastructure reuse and utility-specific requirements.
- Wide-area wireless networks: WiMAX uses licensed spectrum that is described as potentially more secure and reliable, but licensed networks are more expensive and WiMAX has not yet been deployed at scale.The limited deployment creates risks for utility applications compared with more established cellular technologies.
D. Interoperability of Different Communication Systems
Interoperable communication standards are important for integrating renewable energy into the grid, but the standards landscape is large and complex. Wind variability and intermittency further increase demands on communication systems for observability, control, security, reliability, and safety.
- D. Interoperability of Different Communication Systems: Without interoperable communication standards, integrating renewable energy into the grid would be very difficult.Utilities and regulatory groups are addressing interoperability through workgroups and policy initiatives including IEEE P2030.
- D. Interoperability of Different Communication Systems: NIST’s IEEE P2030 interoperability project sought to define coordination among energy technology, information technology, electric power systems, and end-user applications.The initiative was announced in June 2009.
- D. Interoperability of Different Communication Systems: Wind farms can connect to transmission or distribution networks, but high variability and intermittency make their operation challenging for power systems.Large-scale wind integration can affect system observability and controllability.
- D. Interoperability of Different Communication Systems: Communication systems transmit measurements and control signals between wind farms and power systems, supporting monitoring, control, peak-load shaving, and voltage support.Communication deficiencies could negatively affect system security, reliability, and safety.
- D. Interoperability of Different Communication Systems: The paper presents the communication systems used in the Bear Mountain Wind Farm project in British Columbia, Canada.This case study grounds the discussion of grid-integration communication systems in a real renewable-energy project.
A. Introduction to Bear Mountain Wind Farm (BMW)
Bear Mountain Wind Farm is a 102 MW, 34-turbine project whose communication infrastructure supports integration into British Columbia’s transmission network. Its SCADA system links monitoring, data acquisition, control, protection, and external interfaces, with defined fallback behavior during communication failures.
- A. Introduction to Bear Mountain Wind Farm (BMW): Bear Mountain Wind Farm consists of thirty four ENERCON wind turbine generators with a generation capacity of 102 MW.It was the first large-scale wind farm integrated into British Columbia’s transmission network and entered commercial operation in December 2009.
- A. Introduction to Bear Mountain Wind Farm (BMW): BMW’s communication infrastructure supports active-power coordination, reactive-power control, wind-farm protection, and system protection.The infrastructure was specifically designed to support reliable and flexible operation.
- A. Introduction to Bear Mountain Wind Farm (BMW): The BMW communication system carries information for monitoring system status, controlling dynamic energy flows, and transferring sensing and control data across the power grid.Energy flows through the grid while information flows through communication networks among BMW and connected power-system components.
- A. Introduction to Bear Mountain Wind Farm (BMW): BMW SCADA provides data acquisition, remote monitoring, external data exchange, electrical-variable measurement, substation switching, voltage control, and meteorological-data collection.Its interfaces include SCADA REMOTE, PDI, GDA, SCU, VCS, and METEO functions.
- A. Introduction to Bear Mountain Wind Farm (BMW): Authorized SCADA users can access operating states, analyze event data, and modify wind-energy-converter and voltage-control parameters.These controls support tuning under varying power-system conditions and closed-loop voltage regulation at the point of interconnection.
- A. Introduction to Bear Mountain Wind Farm (BMW): If SCADA communication fails or control signals are interrupted, each affected generator automatically defaults to autonomous voltage control at 15% capacity and 1.0 power factor.The paper emphasizes that SCADA’s response to communication breakdowns must be determined case by case.
C. Communication System for Power System Protection & Control and Remedial Action
BMW’s grid integration uses layered communication infrastructure for protection, control, telemetry, alarms, and SCADA. Its RAS combines fiber-based relay communication with power-line-carrier and radio links to support system-level protection and control.
- BMW adds a new 138kV substation at the point of interconnection, with PLC systems linking protection devices and control, telemetry, and alarm data.
- At Chetwynd, SEL relay protection information passes through an SEL 2032 processor to a 2400bps RTU and then to the utility control center via power-line carriers.
- RAS uses pre-planned control actions for predictable contingencies, protecting multiple remotely located equipment and improving whole-system reliability.
- Single-mode fiber pairs on the ADSS line carry Mirrored Bits between SEL 421 relays and provide a separate BMW SCADA channel.
- BMW data, protection information, and line telemetry reach the control center through ADSS fiber and power-line carrier, with updates every 4 seconds.
D. Research Challenges
The paper identifies communication challenges spanning interoperability, real-time monitoring, wireless deployment, SCADA utilization, reliability, and islanding detection. It links robust, standardized, and reliable communications to improved wind-farm operation and grid support.
- Standardization of protocols: Proprietary protocols create communication barriers; standardization, scalability, and interoperability can reduce maintenance effort and improve communication availability.
- Standardization of protocols: Wind intermittency requires high-speed, accurate dynamic control based on real-time system-state estimation, motivating communication frameworks for synchrophasor data.
- Application of wireless technologies: Wireless communications for distributed monitoring, authorization, and control may improve wind-generation reliability and efficiency while reducing life-cycle cost.
- Make use of full capabilities of wind farm SCADA and wind turbine reactive capability: Robust two-way communications can activate advanced wind-farm SCADA and reactive-power functions, improving efficiency, control speed, and grid support.
- Enhance communication systems reliability: Communication failures can constrain wind-farm operation and force output reductions, whereas reliable systems can increase wind-energy yield for owners, utilities, and customers.
- Islanding detection and operation through communication systems: Frequency or voltage-drift methods may detect islanding too slowly or unreliably, while wireless communications or PLC could support faster, more accurate detection and control.
A. Introduction to Photovoltaic Power Systems (PPS)
Photovoltaic power systems range from residential installations below 10kW to commercial and utility-scale systems above 100kW. Communication systems support local, remote, web-based, and metering-quality monitoring across these scales.
- Grid-connected solar systems are classified as residential, commercial, or utility scale.
- Residential installations are below 10kW, commercial systems range from 10kW to 100kW, and utility-scale systems exceed 100kW.
- Utility-scale systems introduced data acquisition for monitoring, while RS232 or USB supports on-site debugging, configuration, and monitoring of one-inverter systems.
- Web-based tools provide current and historical system data, with inverters sending generation information to servers through the Internet.
- RS-485 commonly connects inverters to data loggers, while Ethernet and Internet provide broader monitoring connectivity.
- Monitoring covers array production, inverter output and status, AC-grid conditions, weather, component temperatures, and solar irradiance.
C. Communication Systems for PPS Advanced Applications: Fault Diagnosis
Advanced PPS communication systems enable module-level monitoring and support fault diagnosis, islanding detection, and energy-efficient operation. The paper highlights unresolved tradeoffs involving wireless power use, reliability, coverage, and localization.
- Communication Systems for PPS Advanced Applications: Fault Diagnosis: Minor shading and other non-optimal conditions can substantially reduce photovoltaic-array output, yet output-terminal sensing may not reliably identify the cause.
- Communication Systems for PPS Advanced Applications: Fault Diagnosis: Wireless monitoring can expose the status of individual solar modules, which is useful when panels are installed in difficult-to-access areas.
- Power consumption of the end device: Wireless PPS communications require balancing power consumption, reliability, coverage, throughput, and latency under dynamically changing conditions.
- Power consumption of the end device: Energy-efficient communication networks for solar integration could reduce solar-project life-cycle cost, including losses from non-optimal operation or communications.
- Reliability, coverage, and flexibility: Although wireless communication offers control flexibility, interference, shadowing, and fading can make it unreliable.
- Addressing and localization: Addressing and localization algorithms from wireless sensor networks may help identify failed photovoltaic panels quickly.
- Islanding detection: Wireless or PLC communication could provide fast and accurate islanding detection and control for photovoltaic power systems.
V. CONCLUSIONS
The paper reviews communication technologies for renewable-energy grid integration, presents systems used in the Bear Mountain Wind Farm and photovoltaic systems, and identifies interoperability and research challenges.
- Two-way communications enable the accommodation of distributed renewable energy generation.
- The paper reviews several communication technologies available for grid integration of renewable energy resources.
- Because future systems will use a hybrid mix of technologies, interoperable standards are important.
- The Bear Mountain Wind Farm case includes communication systems for supervisory control and data acquisition, power protection, and control.
- The paper also introduces communication systems used in photovoltaic power systems.
- Distinctive renewable-energy integration characteristics pose communication-system challenges that merit further research.