1 Impact of PEV as Load and Electric Storage on Distribution Operations

Transcription

1 1 Impact of PEV as Load and Electric Storage on Distribution Operations 1.1 Brief Description The objectives of this use case are to demonstrate that the distribution monitoring and controlling functions a) take into account the nearreal time behavior of the PEV as loads and as Electric Storage and b) have the needed input information for the close look-ahead times reflecting the behavior of the PEV as loads and as Electric Storage. The scope of the use case covers the collection of real-time information from large concentrations of connected PEV, from selected AMI sites, and from aggregated PEV load and storage models dependent on observable inputs (e.g., time of day and week, etc.). These object models will need to be developed based on processing data collected from PEV interfaces and AMI. These models will be updated with new information collected from the mentioned sources. Therefore, a PEV Analysis System will need to be developed within the utility IT systems. This system will need to be accessible by DMS and by the Aggregators. The information about the behavior of PEV as load and as Electric Storage combined with the information about regular loads, loads with DR and DER will be used by DMS functions for monitoring and controlling the operations of distribution and immediate transmission systems. The scope of the monitoring functions will include the following analyses: loading of distribution elements, voltage deviations and voltage imbalances, load transfer capabilities, loss components, dynamic voltage limits at the distribution and transmission buses, dispatchable real and reactive loads due to voltage and var control, DR, DER, PEV, and ES, and aggregated load characteristics at the buses of the transmission EMS models. It will also include monitoring the current reliability of the distribution system by running distribution contingency analysis periodically and by event. The controlling functions will include Service Restoration, Voltage, Var, and Watt Control, and Feeder Reconfiguration. The rationales of this use case are based on the fact that the PEV loads are different from other load by its mobility, more dynamic load patterns, and the ability to be used as energy storage. 1.2 Narrative The major advanced DMS functions to be used by distribution operations are as follows: Distribution Operation Model and Analysis (DOMA) Distribution Contingency Analysis (DCA) Fault Location, Isolation, and Service Restoration (FLIR) Impact_of_PEV_as_Load_and_Electric_Storage_on_Distribution_Operations.doc 1 May, 20

2 Voltage, Var, and Watt Control (VVWC) Feeder Reconfiguration (FR) DOMA function DOMA application is based on a real-time unbalanced distribution power flow for dynamically changing distribution operating conditions, including demand response, electric storage, eclectic vehicles, and distributed generation. It analyzes the results of the power flow simulations, checking the adequacy of loading, voltages, and current and voltage imbalances. The model is kept up-to-date by real-time updates of topology, facilities parameters, load patterns and allocation (including PEV loads), and relevant components of the transmission system. In the look-ahead mode, the application checks whether the scheduled or requested demand response, including PEV storage capabilities, may create adverse operating conditions in distribution. Based on this assessment, the schedule or request for load and DER management may be altered or recalled. The function runs periodically, by event, and on demand. The periodicity of the runs is in the range of 3-15 minutes. The by event runs should start within one minute and be completed in one minute. The function consists of the following sub-functions: Modeling transmission/sub-transmission system immediately adjacent to distribution circuits This sub-function provides topology and electrical characteristics of those substation transformers and transmission/sub-transmission portions of the system, where loading and voltage levels significantly depend on the operating conditions of the particular portion of the distribution system. The model also includes substation transformers and transmission/sub-transmission lines with load and voltage limits that should be respected by the application. The transmission related information exchange is accomplished over the EMS DMS interface Modeling distribution circuit connectivity This sub-function provides a topological model of distribution circuits, starting from the distribution side of the substation transformer and ending at the equivalent load center on the secondary of each distribution transformer. A topological consistency check is performed every time connectivity changes. The model input comes from SCADA/EMS, Distribution SCADA, from field crews, from DISCO operator, from AM/FM/GIS, from outage detections by AMI, WMS, and OMS databases, and engineers. Impact_of_PEV_as_Load_and_Electric_Storage_on_Distribution_Operations.doc 2 May, 20

3 Modeling distribution nodal loads This sub-function provides characteristics of real and reactive load connected to secondary side of distribution transformer or to primary distribution circuit in case of primary meter customers. These characteristics shall be sufficient to estimate kw and kvars at a distribution node at any given time and day and include the load shapes and load-to-voltage sensitivities (for real and reactive power) of various load categories, as well as financial attributes. In real-time mode, the nodal loads are balanced with real-time measurements obtained from corresponding primary circuits. A validity check is applied to real-time measurements. The load model input comes from Distribution SCADA, from CIS and Behavior Databases for DR, PEV, and ES, supported by AMI, customer EMS, and contractual agreements and linked with AM/FM/GIS, as well as from selected Smart Meters, from aggregators, and from weather forecast systems. The PEV load models shall include the current loads, the availability and capacity of PEV as Electric Storage, the contractual conditions of the electric storage use (capacity, duration, cost, etc.), and the estimates of short-term load forecast, for lookahead functions Modeling distributed energy resources. This sub-function provides characteristics of real and reactive load generated by DER, connected to secondary side of distribution transformer or to primary distribution circuits. These characteristics shall be sufficient to estimate the generated kw and kvars at a distribution node at any given time and day and shall include the generation schedules for short-term look-ahead timeframes and corresponding financial attributes. They also shall include capability curves. In real-time mode, the nodal generations are balanced with real-time measurements obtained from corresponding primary circuits. A validity check is applied to real-time measurements. The DER model input comes from Distribution SCADA, from CIS and Behavior Databases for DER, supported by AMI and linked with AM/FM/GIS, from selected Smart Meters, from aggregators, from contractual agreements, and from weather forecast systems Modeling distribution circuit facilities This sub-function models the following distribution circuit facilities for 60 Hz and higher frequency simulations: 1. Overhead and underground line segments 2. Switching devices 3. Substation and distribution transformers, including step-down/up transformers 4. Station, feeder, and LV capacitors and their controllers 5. Feeder series reactors 6. Voltage regulators (single- and three-phase) and their controllers Impact_of_PEV_as_Load_and_Electric_Storage_on_Distribution_Operations.doc 3 May, 20

4 7. LTC s and their controllers 8. Distribution generators (synchronous and converter-based) 9. Power Electronic Devices All facilities should be modeled with sufficient details to support the required accuracy of Distribution Operation Modeling and Analysis application Distribution power flow The sub-function models the unbalanced power flow including the impact of automatically controlled devices (i.e., LTCs, capacitor controllers, voltage regulators) and Real Time Pricing (RTP), solves radial and meshed networks with multiple supply busses (DER, Electric Storage) Evaluation of transfer capacity This sub-function estimates the available bi-directional transfer capacity for each designated tie switch. The determined transfer capacity is such that the loading of a tie switch does not lead to any voltage or current violations along the interconnected feeders. The transfer capacity analysis shall take into account the availability and cost of DER, DR, PEV, ES and Volt/Var control Power quality analysis This sub-function performs the power quality analysis by: 1. Comparing (actual) measured and calculated voltages against the limits 2. Determining the portion of time the voltage or imbalance are outside the limits 3. Determining the amount of energy consumed during various voltage deviations and imbalance 4. Recording the time when voltage violations occur 5. Summarizing and analyzing voltage quality parameters retrieved from AMI devices. The power quality parameters will significantly change with the change of the amount and location of PEV loads and will also depend on the use of this load as load or as electric storage. Impact_of_PEV_as_Load_and_Electric_Storage_on_Distribution_Operations.doc 4 May, 20

5 The sub-function provides the ability to estimate the expected voltage quality parameters during the planned changes in connectivity and reactive power compensation Loss analysis This sub-function bases its analysis on technical losses (e.g., I 2 R, core, dielectric) calculated for different elements of the distribution system (e.g., per feeder or substation transformer). For the defined area, these losses are accumulated for a given time interval (month, quarter, year, etc.). They are further compared with the difference between the energy input (based on measurements) into the defined area and the total of relevant billed kwh (obtained from CIS and AMI), normalized to the same time interval. The result of the comparison is an estimate of commercial losses (e.g., metering errors and theft) Estimates of voltage drop in the secondaries. Based on the voltages measured by AMI devices and loads aggregated at the secondary buses of the distribution transformers, the application will derive dependencies of the voltage drop between the bus and the customer terminals. These dependencies will be used as an attribute of the object model of the LV equivalent in the DMS computing applications. The voltage drops in the secondaries will significantly depend on the amount and location of the PEV loads Fault analysis This sub-function calculates a bolted three-phase, line-to-line-to-ground and line-to-ground fault currents for each protection zone associated with feeder circuit breakers and field reclosers. The minimum fault current is compared with protection settings while the maximum fault current is compared with interrupting ratings of breakers and reclosers. If the requirements are not met, the message is generated for the operator. The fault currents will change with the change of the amount and location of the electric storage Evaluation of operating conditions This sub-function determines the difference between the existing substation bus voltage and the substation bus voltages limits. The sub-function also estimates the available dispatchable real and reactive load obtainable via volt/var control, DER, DR, PEV, and ES. Operator or other applications can use this information for selective load reduction. The sub-function provides aggregated at the transmission buses operational parameters to be used in transmission operation models. These characteristics include: aggregated at the buses load-to-voltage dependencies, remedial action schemes parameters, DER protection behavior, etc. Impact_of_PEV_as_Load_and_Electric_Storage_on_Distribution_Operations.doc 5 May, 20

6 1.2.2 Contingency Analysis When there is a significant penetration of PEV with or without storage capabilities, the results of the contingency analysis may differ depending on the amount and location of the connected PEV. On the other hand, for some contingencies, utilizing the capabilities of PEV as electric storage in the supply (discharging) mode may reduce the number and/or duration of customer interruptions. The application performs an N-m contingency analysis in the relevant portion of distribution. The function runs in the following manners: 1. Periodically 2. By event (topology change, load change, availability of control change) 3. Study mode, in which the conditions are defined and the application is started by the user. The application informs the operator on the status of real-time distribution system reliability and prepares a list of decisions for load restoration and the need in enabling the supply of electric storage Fault Isolation and Service Restoration This sub-function running in near-real time may perform in two modes of operations: 1. Closed-loop mode, in which the sub-function is initiated by the Fault location sub-function. It generates a switching order (i.e., sequence) for the remotely controlled switching devices to isolate the faulted section, and restore service to the nonfaulted sections. The solution may include enabling the available PEV as electric storage (as well as DER, DR, and other ES) to support supply of loads connected to healthy sections of the feeder and avoid overloads of backup feeders. It may also include the use of PEV storage capacity to temporarily supply a number of customers until a slower backup source comes into service. The decision to use PEVs as a source of supply will be made based on the actual connectivity of PEV, on the contractual conditions of their use, and on their current behavioral models. The commands for execution of the switching order should be delivered over near real-time communications. 2. Advisory mode, in which the sub-function is initiated by the Fault location sub-function. It generates a switching order for remotely- and manually-controlled switching devices to isolate the faulted section and for remotely- and manuallycontrolled switching devices and DR, DER ES, and PEV storage devices to restore service to the non-faulted sections. The switching order is presented to operator for approval and execution When work is completed, the sub-function is instructed to generate a switching order for restoration of the normal configuration. The generated switching orders are based on considering the availability of remotely controlled switching devices, feeder paralleling, creation of islands supported by distributed energy resources, and on cold-load pickup currents. The cold-load pickup may Impact_of_PEV_as_Load_and_Electric_Storage_on_Distribution_Operations.doc 6 May, 20

7 significantly depend on the behavior of the PEV loads during the repair time. Charging of some of the PEV used as electric storage may be delayed to reduce the cold-load pickup current Voltage, Var, and Watt Control (VVWC) with DR, DER, PEV, and ES The application calculates the optimal settings of voltage controller of LTCs, voltage regulators, Distributed Energy Resources, power electronic devices, capacitor statuses, and may enable PEV electric storage means for optimizing the operations following current objectives. The application takes into account operational constraints if both distribution and transmission operations, and, if so opted, it takes into account real-time energy prices, when the objective is cost minimization. The optimization of voltage and var control is a complex task, which requires a large amount if input data and a sophisticated algorithm. The task will become much more complex and effective with significant penetration of DER, DR, PEV, ES, and power electronics. The optimization is based on searching the best combination of controllable variables applied to the power flow simulations. The power flow simulation with the best combination shall result in the optimal solution for the selected objective, respecting all imposed operational constraints. Because of the complex inter-relationships between the controllable variables, loads and power flows, a comprehensive operation model shall be used as a background of the VVWC application. This application is based on a real-time unbalanced distribution power flow for dynamically changing distribution operating conditions, including loads depending on voltage, demand response, electric storage, eclectic vehicles, distributed generation activities, and reactions of locally controlled distributed intelligence schemes. The model is kept up-to-date by real-time updates of topology, facilities parameters, load patterns, and relevant components of the transmission system. The application, if so opted, shall also issue operational requirements to Demand Response means, to Electric Storage devices, as well as to Electric Transportation installations in order to optimally achieve its objective. The application shall be able to utilize selected AMI data directly from the Smart Meters, as well as from the typified object models updated by AMI information (Fig. 1). Impact_of_PEV_as_Load_and_Electric_Storage_on_Distribution_Operations.doc 7 May, 20

8 Updates Integrated Volt/var/Watt Optimization Setpoints Setpoints/Statuses DR Triggers LTC/VR VAR SOURCES Distribution Operation Model DR execution DR/DER PEV/ES AMI Critical points Figure 1. Integration of Volt/Var/Watt Optimization with DR/DER/PEV/ES in Advanced DMS Impact_of_PEV_as_Load_and_Electric_Storage_on_Distribution_Operations.doc 8 May, 20

9 1.2.5 Multi-level Feeder Reconfiguration (MFR) This application recommends an optimal selection of feeder(s) connectivity for different objectives. It supports three modes of operation: 1. Closed-loop mode, in which the application is initiated by the Fault Location, Isolation and Service Restoration application, unable to restore service by simple (one-level) load transfer, to determine a switching order for the remotelycontrolled switching devices to restore service to the non-faulted sections by using multi-level load transfers, demand response, electric storage capabilities, including PEV, and DER devices. 2. Advisory mode, in which the application is initiated by SCADA alarms triggered by overloads of substation transformer, segments of distribution circuits, or by DOMA detecting an overload, or by operator who would indicate the objective and the reconfiguration area. In this mode, the application recommends a switching order to the operator. The switching order may include using multi-level load transfers, demand response, electric storage capabilities, including PEV, and DER devices. 3. Study mode, in which the application is initiated and the conditions are defined by the user. The application performs a multi-level feeder reconfiguration to meet one of the following objectives: a. Optimally restore service to customers utilizing multiple alternative sources. The application meets this objective by operating as part of Fault Location, Isolation and Service Restoration. b. Optimally unload an overloaded segment (load balancing). This objective is pursued if the application is triggered by the overload alarm from SCADA, or from the Distribution Operation Modeling and Analysis, or from Contingency analysis. These alarms are generated by overloads of substation transformer or segments of distribution circuits, or by operator demand. c. Minimize losses d. Minimize exposure to faults e. Equalize voltages The last three objectives are selected by engineer/planner. Impact_of_PEV_as_Load_and_Electric_Storage_on_Distribution_Operations.doc 9 May, 20

10 1.3 Actor (Stakeholder) Roles Describe all the people (their job), systems, databases, organizations, and devices involved in or affected by the Function (e.g. operators, system administrators, technicians, end users, service personnel, executives, SCADA system, real-time database, RTO, RTU, IED, power system). Typically, these actors are logically grouped by organization or functional boundaries or just for collaboration purpose of this use case. We need to identify these groupings and their relevant roles and understand the constituency. The same actor could play different roles in different Functions, but only one role in one Function. If the same actor (e.g. the same person) does play multiple roles in one Function, list these different actor-roles as separate rows. Actor Name Actor Type (person, device, system etc. Actor Description Domain Energy Market Clearinghouse Company/System Wide-area energy market operation system providing high-level market signals for ISO/RTO and Utility Operations ISO/RTO Company/System Wide-area power system control center providing highlevel load management and other signals for Utility Operations Utility Operations Company/System Distribution, transmission and generation management system providing operations with distribution/transmission/generation-related objectives, constraints, and input data; performing monitoring and, controlling of the power system operations. Utility Apps Systems DMS, OMS, WMS, GIS, Demand Response Management System, PEV Analysis System and Behavioral Model Databases, etc. Controlling DR, DER, PEV and ES charging/discharging; processing and storing data on load management programs, contracts, relevant historic information, creating behavioral models, collecting, processing, and storing customer-specific power quality and reliability chractestics, etc. Impact_of_PEV_as_Load_and_Electric_Storage_on_Distribution_Operations.doc 10 May, 20

11 Actor Name Actor Type (person, device, system etc. Actor Description Domain Metering/Billing/ Utility Back Office Systems CIS, AMI System Aggregator/Energ y Services Company Company Intermediary entity between Utility and group of customers Customer Premises with PEV Grouping (Community), Group Description Actor Name Actor Type (person, device, system etc.) Actor Description Replicate this table for each logic group. 1.4 Information exchanged Describe any information exchanged, including between which Actors. Impact_of_PEV_as_Load_and_Electric_Storage_on_Distribution_Operations.doc 11 May, 20

12 Interface # Information Object Name Information Object Description 1 Request for aggregated load management (congestion management) in a particular wide area, price signals. 1 Utility operation data and available dispatchable load by means of DR, DER, PEV and ES 2 Energy and Ancillary Service Prices From ISO/RTO and Utility Operations, may be in a day ahead timeframe, in a hours in advances, or in a near real time via RTP signal From and Utility Operations to ISO/RTO, near real-time and forecasts for look-ahead studies. From Energy Market Clearing House, to Aggregator and Utility Operations,, may be in a day ahead timeframe, in a hours or minutes in advances 2 Bids for ancillary services From Aggregator and Utility Operations to Energy Market Clearing House 3 Real Time Prices (market-based or reliability based), Direct triggers for enabling PEV storage use, charge interruptions, requests for near-real time measurements 3 Confirmations on execution of direct controls, requests, and reaction on RTP, transmission of requested real-time measurements From Utility Operations to Customer. VVWC and DOMA determine the voltage and loading critical sites and request near real-time measurement updates. VVWC under load reduction objective determines in which voltage-critical points load reduction would significantly increase the voltage and sends a triggering signal to this point for exercising discharge of PEV electric storage into grid. VVWC then lowers the voltage and adjusts capacitors to utilize the additional room created by the PEV discharge. The DCA and FLIR determines in which nodes the electric storage discharge would improve the restoration results and issue triggering signals to the corresponding sites. In case of an aggregated request for load reduction, the utility issues triggering commands to a large number of customers for demand response, electric storage discharge, and DER starts. From selected customers with BMS to Utility Operations Impact_of_PEV_as_Load_and_Electric_Storage_on_Distribution_Operations.doc 12 May, 20

13 4 Load and consumption data, Start and End times for DR, ES, PEV connection and discharge. Other measurements. From customer to Metering Billing. Paeriodic data (every 1-5 min), by event data 4 From Metering Billing to customer From ISO/RTO to Market Clearing House 6 From Market Clearing House to ISO/RTO From Aggregator/Energy Services Company to Customer 8 From Customer to Aggregator/Energy Services Company Impact_of_PEV_as_Load_and_Electric_Storage_on_Distribution_Operations.doc 13 May, 20

14 11 From Aggregator/Energy Services Company to ISO/RTO 11 From to ISO/RTO to Aggregator/Energy Services Company 12 From Aggregator/Energy Services Company to Metering/Billing 12 From Metering/Billing to Aggregator/Energy Services Company 12 Measurements and other data collected from customers From Metering/Billing to Utility Operations for processing in APPS 12 Request for information updates From Utility Operations to Metering/Billing 13 Exchange with object model updates, calculation results, switching orders, etc. From Application to Application to other utility IT systems 14 From Aggregator to Utility Operations 14 From Utility Operations to Aggregator Impact_of_PEV_as_Load_and_Electric_Storage_on_Distribution_Operations.doc 14 May, 20

15 Energy Market Clearinghouse 6 ISO/RTO Utility Operations App 13 App 3 12 Aggregator/Energy Services Company 8 12 Metering/Billing/ Utility Back Office 15 Meter ESI 5 4 Market and/or financial interfaces Sub Meter/ EUMD Customer EMS (optional) (Premise & Off-Premise) PEV (as load and electric storage) 7 Customer Premises Energy information interfaces Metering information interfaces PEV: Plug-in Electric Vehicle ISO: Independent System Operator RTO: Regional Transmission Operator ESI: Energy Services Interface EMS: Energy Management System (optional) EUMD: End Use Measurement Device Figure 2. Use Case Diagram Impact_of_PEV_as_Load_and_Electric_Storage_on_Distribution_Operations.doc 15 May, 20

16 Actor in Domain Category Standards Requirements and notes 8. Policy 7. Business Objectives 6. Business Procedures 5. Business Context 4. Semantic Understanding information objects standards this actor understands are identified here 3. Syntactic Interoperability transfer syntax standards are identified here 2. Network Interoperability Addressing and routing standards here 1. Basic Connectivity Physical standards here Shared Meaning of Content Object modeling Resource Identification Universal identifiers Time Synch & Sequencing Security and Privacy Logging & Auditing Transaction State Management System Preservation Quality of Service Discovery & Configuration System Evolution & Scalability Electromechanical Impact_of_PEV_as_Load_and_Electric_Storage_on_Distribution_Operations.doc 16 May, 20