The Rajasthan Rajya Vidyut Prasaran Nigam (RVPNL) has extended the time for implementing the standard operating procedure (SOP) for first-time charging (FTC) of battery energy storage systems installed at already commissioned and to-be-commissioned renewable energy projects until September 30, 2026.

If the renewable energy project developers fail to comply with the SOPs by the deadline, the renewable energy project may be disconnected from the grid, and/or the green energy open access/open access granted to the project may be withdrawn or disallowed by the competent authority without further notice.

Such projects must be installed under the Rajasthan Integrated Clean Energy Policy 2024.

The SOP states that the FTC of a renewable energy project will not be allowed without the associated battery storage system.

The SOP guidelines for the FTC of renewable energy projects linked with battery storage were issued in May.

According to the SOP, a battery energy storage system will comprise a power conversion system (PCS), an energy storage system, and a battery management system.

Under the SOP, Battery storage system developers must submit an undertaking confirming compliance with the Central Electricity Authority’s technical standards for grid connectivity. They must also provide details such as the battery manufacturer, battery type, battery design, self-discharge rate, depth of discharge, life cycle, and round-trip efficiency.

Developers must provide available test certificates for battery cells, their power ratings, and the favorable operating temperature range.

Developers must also submit details of the PCS used in the project, including the manufacturer, type of charge controller, inverter power rating and efficiency, minimum inverter response time, and available test certificates for the PCS.

The SOP requires several battery storage system parameters to be telemetered to the State Load Dispatch Center.

The PCS may consist of one or more parallel units and may include a bidirectional converter capable of operating in both battery-charging and battery-discharging modes.

The PCS must ensure that AC power is efficiently converted from the DC power of the battery arrays and bidirectionally transferred to or from the distribution line without causing harmonics beyond the limits prescribed under CEA regulations.

It must also include a remote synchronization feature, in addition to the standard synchronization used while starting the PCS online. The remote synchronization feature enables the PCS to synchronize its voltage and frequency with any other remote AC bus or generator.

The PCS must have black-start capability and four-quadrant control capability. It must also be capable of load following, including photovoltaic smoothing, with voltage maintained within ±5% of the nominal value under normal operating conditions and within ±10% under emergency conditions.

The PCS must have a synchro-check function to enable parallel operation with the grid, diesel generators, and photovoltaic generators.

The PCS must be capable of operating in four modes.

In active and reactive power control mode, the PCS controls the output active and reactive power supplied to the grid based on reference values that may be set locally or remotely.

In voltage and frequency control mode, the PCS controls its own voltage and frequency, enabling it to create an islanded grid. Voltage and frequency control are possible when the PCS operates in voltage-source mode.

In virtual synchronous generator mode, the PCS operates as a voltage source converter. Under this mode, the battery storage system can provide its own voltage and frequency to an islanded grid or operate in parallel with the utility grid in grid-connected mode.

In voltage and frequency droop mode for parallel operation, voltage droop enables reactive power sharing when the battery storage system operates in islanded mode or in parallel with other voltage sources. Frequency droop enables active power sharing when the battery storage system operates in islanded mode or in parallel with other voltage sources.

Recently, RVPNL issued draft guidelines mandating that battery storage systems installed with renewable energy captive and open access projects be charged during solar peak hours using power from their own generation.

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