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In-depth HPLC Applications for Building New Power Systems

[Shanghai, China, May 11, 2022]

The Chinese central government's proposal in 2021 to build new renewable energy power systems has brought unprecedented development opportunities to service providers engaged in distributed photovoltaics (PV), electricity spot market transactions, and orderly power usage. This places higher requirements on efficiency and performance for power grid supply and demand. High-speed power line carrier communications (HPLC) is a manifestation of IoT communication technologies, which allows for frequent collection of user load data via the power consumption data collection system, serving as the communications bedrock for efficient new power system operations.

The following introduces the eight in-depth HPLC applications — frequent data collection, automatic transformer district identification, proactive power outage reporting, communication performance monitoring and network optimization, unified ID management, automatic archive synchronization, precise clock management, and phase topology identification.

Strengthening HPLC to Bolster New Power Systems

New power systems are the most important transformation in the energy framework of the future. Unlike traditional power grid planning and construction, new power systems connect power generation, power grids, and users, to apply in-depth "source-grid-load-storage" interactions.

To adapt to service changes, the low-voltage power utilization and collection system will be upgraded to meet the need for bidirectional power flow and multi-load power usage. This can help with the implementation of marketing-distribution convergence, local consumption of distributed renewable energy, and real-time flexible source and load adjustments.

Connectivity technologies are essential to seeing through this transition, as they significantly boost network scale, service bandwidth, and real-time communications. Low-voltage power distribution and utilization are trending towards more connected solutions. In-depth deployment of IoT communication technologies in the low-voltage power distribution and utilization field, as exemplified by HPLC, is a crucial step toward building the power systems of the future.

Values of HPLC in a new power system

Interpretation of the Eight HPLC Applications

Frequent data collection: Power metering data, including instantaneous data, can be collected on a frequent basis, and used to analyze the aging trends of power supply lines, as well as to monitor the voltage quality and load fluctuation of power grids. Power grid terminal sensing data can be fully collected at a minute level, providing key support for a wide range of high-value power grid services.

The advantages of minute-level collection are as follows:
◦ Distributed PV access: Collects real-time information, such as active/reactive power, voltage distribution, grid-connected current, power quality, and switch status. Collects energy yields from PV meters to implement local unified management and control of distributed PV across the entire transformer district.
◦ Electricity spot market transactions: Accurately predicts loads, ensuring real-time balance between power supply and demand. Completes electricity sales on the spot market within minutes, maximizing economic benefits.
◦ Device status monitoring: Performs local calculation and analysis to collect data on device operations, such as meter inaccuracy and module in-position detection. Obtains the operating conditions in real time via data collectors that are connected to the sensors.
◦ Power quality monitoring: Collects real time data on the voltage, current, and three-phase imbalance threshold-crossing. Supports load imbalance and timely phase change load balancing. Collects data on the voltage qualification rate, and reports low voltage alarms.
◦ Real-time line loss: Refines transformer district line loss, collects and calculates power utilization data across all periods, and detects and reports power exception alarms in a timely manner.
◦ Detection of abnormal cable connections and suspected power outage: Monitors and analyzes abnormal areas and fault points based on the voltage and current of the transformer district's master meter and user meters. Determines power outage information based on the RS-485 interface status of the data collector.

Automatic transformer district identification: This application has been commercially deployed, and the average accuracy of identifying user-transformer relationships has soared to a staggering 99%, improving the line loss management efficiency of transformer districts, as well as economic feasibility of power grids.

HiSilicon offers an industry-leading user-transformer relationship identification solution, which does not require replacing or adding devices. This solution is capable of onsite upgrades that automatically match user-transformer relationships, and enable you to manage high-loss transformer districts and refine line loss.

Identification process

In terms of technical implementation, PLC is used to automatically sense and collect channel characteristics and changes, such as voltage zero-crossing signals, signal strength, and power line noise. Nominal-the best (NTB) and signal-to-noise ratio (SNR) are used to comprehensively evaluate transformer district characteristic parameters, and select the network with the optimal characteristic parameters.
◦ The precision of the zero-crossing circuit is within 20 μs, so that the 220 V characteristics of power lines can be effectively identified.
◦ A powerful algorithm is used to calculate NTB statistics among networks, outperforming industry peers.
◦ SNR characteristics provide an effective supplement to protocols, thereby boosting the identification success rate.

Power outage reporting: Refers to the proactive reporting of power outage or recovery events. This makes repair work proactive, rather than passive, improving power supply reliability and customer service assurance.

HiSilicon uses an AI-based electrical topology solution to calculate the actual physical line loss and line impedance. An alarm is generated before a fault occurs, and the power failure point can be accurately located, to support quick repairs. There is no need to replace existing devices or transmit characteristic current signals to the power grid, so that power quality remains unaffected and power grid security risk is mitigated.

In order to implement the solution technology, devices are grouped based on SNR information. The timestamp difference is precisely calculated to differentiate layers. In addition, the mapping between inbound and outbound cables is identified based on the power information.

Communication performance monitoring and network optimization: This application makes network risks predictable via communication performance monitoring data, such as the node signal strength, adjacent node information, and network path information, to allow for network optimization. The application also allows you to evaluate the operating states of devices provided by chip and module vendors, analyze network operations, and adjust HPLC performance parameters to optimize the communication network. The network operating state is visualized, and a data collection framework is provided to report warnings about transformer districts or meters with potential communication risks.
◦ Obtains network topology for all transformer districts.
◦ Obtains adjacent network information for all transformer districts.
◦ Reports the uplink and downlink communication success rates for more than 90% carrier modules.
◦ Reports the online status and offline times of more than 90% carrier modules.

In short, the master station evaluates the communication risks of transformer districts or meters based on the obtained information, generates warnings for potential risks, and analyzes the causes of problems based on geographical and user information, thereby providing crucial guidance for onsite O&M personnel.

ID management: Relies on the globally unified IoT ID management system to establish comprehensive IoT device IDs for HPLC chipsets. Thanks to this, carrier assets for power grid devices can enjoy full lifecycle management of carrier assets. The identity authentication mechanism for each chip and module is used to prevent unauthorized device access and bolster network security.

ID management process

Archive synchronization: Uses transformer district identification to synchronize meter archives and device parameters in both directions, ensuring optimal archive accuracy. This application also improves the consistency of user-transformer relationships and marketing-distribution network systems. Archive synchronization features two modes: 1. Upon receiving a new meter event reported by a data concentrator, the collection system compares this new event with the archive in the marketing system, and then delivers the correct archive to the data concentrator. For an incorrect archive, technical personnel need to check the meter information onsite. 2. Upon receiving a new meter event reported by a data concentrator, the collection system synchronizes the archive in the marketing system, and then delivers new meter parameters to the data concentrator.

Clock management: Clock synchronization and precise management between meters and data concentrators provide technical support for the implementation of time-of-use and multistep electricity price policies. The precise clock management process is as follows:
◦ A data concentrator monitors meter clock errors in the transformer district: It periodically collects clock information of downstream meters, compares the clock information with its own, and reports an event to the master station whenever a clock error occurs.
◦ The master station evaluates the clock deviation of the data concentrator in real time and synchronizes the clock.
◦ For transformer districts with serious clock problems, the master station initiates real-time meter error collection, obtains the clock information of meters via transparent transmission, compares the clock information with that of the master station, and filters out meters with clock errors.
◦ The master station initiates a point metering time calibration for meters whose clock exceeds the broadcast time calibration range.

Phase topology identification: Accurately identifies the relationships between phases A, B, and C of each meter and the line topology. This enhances the three-phase imbalance and phase-based line loss management of the power distribution network, and provides for a more reliable power supply.
◦ The reporting rate and accuracy of phase topology identification is now 99% (except for meters connected to data collectors).
◦ The reporting rate and accuracy of abnormal cable connection is also 99% (except for meters connected to data collectors).

Future Prospects for HPLC Applications in New Power Systems

HPLC has played an important role in the centralized metering services of power grids, and the service transformation of new power systems places more stringent requirements on in-depth HPLC applications. For example, services such as grid-connected PV and electricity spot market transactions require real-time frequent data collection. Product solutions can be accurately evaluated based on the detection of AC and NTB zero-crossing, to ensure the accuracy of transformer district identification. Test indicators such as HPLC white noise, impulse noise, and single-frequency noise are added for the dual-mode standard, and other test indicators such as sensitivity and anti-adjacent-channel interference are added for HRF to improve communications reliability. Electrical topology identification and minute-level data collection can be used to improve the line loss management efficiency of transformer districts, and the economic feasibility of power grids.

HPLC is widely regarded as the optimal communications solution for low-voltage transformer districts, and will be deployed across more applications, extract more value from data, and refine line loss, thereby improving power supply reliability and realizing bona fide transformer district autonomy. In the power distribution field, HPLC will also help implement power distribution automation. When used with devices such as IoT smart sensors, edge computing converged gateways, and transformer district converged terminals, HPLC can implement full-process data measurement, collection, and transmission, forging the way toward a plug-and-play, interconnected world.

PLC has been widely used in the power grid centralized metering market, and will surely expand into energy fields like distributed PV, orderly charging of electric vehicles, and energy storage, as well as smart home and outdoor lighting sectors.

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