Talking about the application scenarios and economic benefit analysis of grid-side energy storage power stations

It should be able to store and manage records of remote signal changes, protection actions, accident tripping, as well as voltage, current, power, power factor, battery cell temperature (lithium-ion batteries), pressure (flow batteries), light, wind speed, and air pressure exceeding the limit, so that users can easily trace the history of system events and alarms, query statistics, and analyze accidents.

Figure 20 Historical event query

4.4.8 Power quality monitoring

It should be possible to continuously monitor the power quality of the entire microgrid system, including steady-state and transient states, so that managers can grasp the power quality of the power supply system in real time, so as to promptly discover and eliminate power supply instability factors.

1) The main interface of the power supply system should be able to display in real time the communication status of the monitoring device at each power quality monitoring point, the total distortion rate of the A/B/C phase voltage at each monitoring point, the percentage of three-phase voltage imbalance and the positive/negative/zero-sequence voltage values, and the percentage of three-phase current imbalance and the positive/negative/zero-sequence current values;

2) Harmonic analysis function: The system should be able to display the total harmonic distortion rate of A/B/C three-phase voltage, the total harmonic distortion rate of A/B/C three-phase current, the total distortion rate of odd harmonic voltage, the total distortion rate of odd harmonic current, the total distortion rate of even harmonic voltage, and the total distortion rate of even harmonic current in real time; it should be able to display the 2-63th harmonic voltage content rate, the 2-63th harmonic voltage content rate, the 0.5-63.5th interharmonic voltage content rate, and the 0.5-63.5th interharmonic current content rate in a bar graph;

3) Voltage fluctuation and flicker: The system should be able to display the A/B/C three-phase voltage fluctuation value, A/B/C three-phase voltage short flicker value, A/B/C three-phase voltage long flicker value; it should be able to provide the A/B/C three-phase voltage fluctuation curve, short flicker curve and long flicker curve; it should be able to display voltage deviation and frequency deviation;

4) Power and energy measurement: The system should be able to display the active power, reactive power and apparent power of the three phases A/B/C; it should be able to display the total active power, total reactive power, total apparent power and total power factor of the three phases; it should be able to provide active load curves, including daily active load curves (broken line type) and annual active load curves (broken line type);

5) Voltage transient monitoring: When power quality transient events such as voltage swell, voltage sag, and short-term interruption occur, the system should be able to generate an alarm, and the event can be notified to relevant personnel in the form of pop-up windows, flashing, sound, text message, phone call, etc.; the system should be able to view the waveforms before and after the corresponding transient event occurs.

6) Power quality data statistics: The system should be able to display the statistical data stored for 1 minute and 2 hours, including mean, maximum, minimum, 95% probability value, and root mean square value.

7) Event record viewing function: The event record should include the event name, status (action or return), waveform number, over-limit value, fault duration, and time of event occurrence.

Figure 21 Microgrid system power quality interface

4.4.9 Remote control function

It should be possible to remotely control the equipment in the entire microgrid system. System maintenance personnel can complete remote control operations through the main interface of the management system and follow the operation sequence of remote control preset, remote control return, and remote control execution to timely execute the corresponding operation commands of the dispatching system or station.

Figure 22 Remote control function

4.4.10 Curve Query

It should be possible to directly view various electrical parameter curves in the curve query interface, including three-phase current, three-phase voltage, active power, reactive power, power factor, SOC, SOH, charge and discharge capacity changes and other curves.

Figure 23 Curve Query

4.4.11 Statistical Reports

It has the function of scheduled meter reading and summary statistics. Users can freely query the power consumption of each distribution node in any time period since the normal operation of the system, that is, the statistical analysis report of the incoming power consumption of the node and the power consumption of each branch circuit. It can conduct statistical analysis on the exchange of electric energy between the microgrid and the external system; analyze the energy saving and benefits of the system operation; analyze the reliability of the microgrid power supply, including the annual power outage time and the number of annual power outages; and analyze the power quality of the grid-connected microgrid's grid-connected points.

Figure 24 Statistical report

4.4.12 Network topology diagram

The system supports real-time monitoring of the communication status of each device connected to the system, and can fully display the entire system network structure; it can diagnose the communication status of the equipment online, and automatically display the faulty equipment or components and their faulty parts on the interface when a network anomaly occurs.

Figure 25 Microgrid system topology interface

This interface mainly displays the microgrid system topology, including the system components, grid connection methods, circuit breakers, meters and other information.

4.4.13 Communication Management

The communication status of devices in the entire microgrid system can be managed, controlled, and data can be monitored in real time. System maintenance personnel can right-click the main program of the management system to open the communication management program, and then select communication control to start all ports or a certain port to quickly view the communication and data status of a certain device. The communication should support ModbusRTU, ModbusTCP, CDT, IEC60870-5-101, IEC60870-5-103, IEC60870-5-104, MQTT and other communication protocols.

Figure 26 Communication Management

4.4.14 User Rights Management

It should have the function of setting user rights management. User rights management can prevent unauthorized operations (such as remote control operation, operation parameter modification, etc.). You can define the login name, password and operation rights of users of different levels to provide reliable security for system operation, maintenance and management.

Figure 27 User permissions

4.4.15 Fault Recording

When a fault occurs in the system, it should be able to automatically and accurately record the changes in the relevant electrical quantities before and after the fault. By analyzing and comparing these electrical quantities, it plays an important role in analyzing and handling accidents, judging whether the protection is operating correctly, and improving the safe operation level of the power system. Among them, the fault recording can record a total of 16 items, each recording can trigger 6 segments of recording, and each recording can record 8 cycles before the fault and 4 cycles after the fault. The total recording time is 46 seconds. Each sampling point recording contains at least 12 analog quantities and 10 switch quantity waveforms.

Figure 28 Fault recording

4.4.16 Accident Recall

It can automatically record all real-time scanning data for a period of time before and after the accident, including switch position, protection action status, telemetry, etc., forming the data basis for accident analysis.

Users can define the start event of accident recall. When each event occurs, the relevant point data of the 10 scanning cycles before the accident and the 10 scanning cycles after the accident are stored. The start event and the monitored data points can be specified and modified by the user at will.

Figure 29 Accident Recollection

4.5 System Hardware Configuration List

5 Conclusion

In areas where the installed capacity of new energy sources accounts for a large proportion and the system peak-shaving demand is high, the reasonable configuration of large-capacity, medium- and long-term energy storage power stations is an objective need to support the construction of new power systems and the high proportion of new energy power consumption. Based on a large-capacity centralized grid-side energy storage demonstration project, this paper constructs a shared energy storage business model, explores the market-based provision of energy storage capacity leasing services, and constructs a capacity electricity price mechanism for grid-side energy storage power stations to promote energy storage power stations to participate in relevant power markets. After calculation and analysis, the investment return of the project is acceptable and basically feasible at the economic level. In the future, it is still necessary to accelerate the construction of various power markets, improve the transaction varieties and price mechanisms of the power auxiliary service market, promote energy storage power stations to participate in various power markets, and maximize the role of new energy storage power stations.