Grid simulators are more advanced programmable AC power supplies with additional load simulation capabilities to bidirectionally source and sink AC power between the equipment under test (EUT) as per those testing specifications and requirements by applicable regulations such as IEC 61000 series and IEE 1547 for DER testing. Primary grid simulator manufacturers in the world include Chroma ATE, Cinergia, Pacific Power Source, Keysight Technologies and ActionPower. This article is primarily a technical comparison that targets the differences and application uses between ActionPower’s TITAN grid simulator and Chroma ATE’s 61815 regenerative grid simulator from user-experience and EUT- and use-case-oriented perspectives.
Introduction to ActionPower TITAN Grid Simulator
The ActionPower TITAN Grid Simulator is a regenerative, four-quadrant programmable AC power platform designed for advanced grid compliance testing, power hardware-in-the-loop (PHIL), and bidirectional energy interaction scenarios commonly encountered in modern DER validation. There are more options of grid emulators by ActionPower but in this article we only cover the technical details of their TITAN.
Unlike conventional AC power sources that primarily focus on voltage synthesis, TITAN is architected from the outset as a grid emulator, capable of operating seamlessly as both an AC source and an active grid-side load. This bidirectional capability allows TITAN to not only supply distorted or abnormal grid conditions to the EUT, but also to absorb returned energy from grid-tied converters, inverters, chargers, and power electronics under dynamic operating states.
From a system perspective, TITAN targets testing environments where dynamic grid behavior, fast transients, and energy flow reversibility are not optional but mandatory—such as PV inverters, ESS PCS, EV chargers, V2G systems, and microgrid controllers.
Core Architectural Design Philosophy
At the architecture level, TITAN adopts a high-power regenerative topology combined with centralized grid synthesis control. This allows the system to maintain:
- Continuous four-quadrant operation across voltage, current, and power directions
- Stable grid impedance emulation under rapidly changing load or generation states
- High-efficiency energy regeneration back to the utility grid, minimizing thermal dissipation
Unlike modular rack-parallel AC sources that scale power by stacking independent units, TITAN is typically deployed as an integrated cabinet or tower-class system, ensuring that key dynamic parameters such as slew rate, short-circuit current, and transient response—are preserved at high power levels.
This architectural choice becomes particularly relevant when testing EUTs above several hundred kilowatts, where parallelized rack systems may introduce coordination latency, uneven current sharing, or degraded transient performance.
Grid Emulation Capabilities and Compliance Scope
TITAN is designed to address a broad range of grid disturbance and compliance scenarios defined in international standards, including but not limited to:
- Voltage dips, swells, and interruptions (IEC 61000-4-11, IEC 61000-4-34)
- Harmonic and interharmonic voltage distortion (IEC 61000-4-7, IEC 61000-4-13)
- Frequency deviations, ROCOF, and phase jump events (IEEE 1547 / IEEE 1547.1)
- Unbalanced and asymmetrical three-phase grid conditions
Crucially, TITAN maintains tight RMS voltage regulation even when harmonic and interharmonic components are superimposed—a requirement explicitly emphasized in several IEC test methodologies. This enables repeatable and standards-aligned testing without external compensation or waveform correction layers.
EUT-Oriented Use Case Alignment
From a user and EUT integration standpoint, TITAN is commonly positioned in test setups where the grid simulator must interact with equipment that is electrically aggressive toward the grid, such as:
- Grid-following and grid-forming inverters operating under fault ride-through
- Regenerative EV chargers and V2G-enabled charging systems
- Energy storage PCS with frequent mode transitions between charge and discharge
- Multi-channel or parallel EUT configurations requiring synchronized grid behavior
In these scenarios, the ability of TITAN to actively sink power with controlled impedance characteristics, rather than relying on passive dumping or external loads, significantly simplifies test bench architecture and improves safety and repeatability.
Introduction to Chroma 61815 Regenerative Grid Simulator
The Chroma ATE 61815 Regenerative Grid Simulator is a high-power, bidirectional AC grid simulation platform primarily developed for compliance testing of grid-connected power electronic equipment. It is widely deployed in certification laboratories, inverter manufacturers, and test houses where adherence to standardized grid disturbance profiles is the dominant requirement.
Positioned as part of Chroma’s long-established power electronics test ecosystem, the 61815 series emphasizes standards-oriented waveform synthesis, regenerative energy handling, and compatibility with automated compliance workflows, particularly for DER, PV inverter, and PCS validation against IEC 61000 and IEEE 1547-related test procedures.
System Architecture and Power Topology
The 61815 adopts a regenerative AC power architecture that enables four-quadrant operation, allowing it to source and sink active power during grid-interactive testing. Returned energy from the EUT is regenerated back to the utility grid, significantly reducing heat dissipation and external load dependency compared with non-regenerative AC sources.
From a system design standpoint, Chroma typically implements the 61815 as a modular power system, where overall power capacity is scaled by parallelizing multiple internal or external power modules. This approach offers flexibility in system configuration and allows users to tailor installed power to specific test requirements without committing to a single monolithic cabinet.
Such modularity is particularly attractive in laboratory environments where test demand varies across projects, or where equipment needs to be repurposed across different voltage and power classes.
Grid Simulation and Disturbance Capability
The 61815 is engineered to generate a comprehensive range of grid disturbance conditions required by international grid-compliance standards, including:
- Programmable voltage dips, swells, and interruptions
- Frequency variation and phase shift events
- Harmonic and interharmonic voltage injection within defined limits
- Three-phase unbalance and asymmetrical grid conditions
These capabilities align closely with the procedural requirements outlined in IEC 61000-4 series and IEEE 1547.1 test methods, making the 61815 a common choice in certification-driven test scenarios, where waveform fidelity and repeatability are prioritized over extreme transient dynamics. In practice, waveform generation and disturbance sequencing are often executed through predefined profiles or scripted test routines, enabling standardized test execution and simplified reporting for compliance purposes.
Application Focus and Typical EUT Scenarios
The Chroma 61815 is frequently deployed in environments where the grid simulator functions primarily as a reference grid source, rather than an actively interacting grid participant. Typical EUTs include:
- Grid-following PV inverters undergoing type testing
- Energy storage PCS evaluated under steady-state charge/discharge conditions
- AC power conversion equipment subject to standardized grid fault sequences
- Products undergoing third-party or in-house certification validation
In these applications, the grid simulator’s role is to present controlled, repeatable grid conditions to the EUT, while absorbing returned energy in a stable and standards-compliant manner. The emphasis is placed on test reproducibility, automation compatibility, and procedural alignment, rather than on real-time grid impedance shaping or aggressive transient interaction.
Architecture & Application-Oriented Engineering Comparison
The following comparison focuses on architectural choices, dynamic performance characteristics, and typical application alignment rather than isolated specification values. Parameters are interpreted from a system-level testing perspective, especially under high-power and bidirectional operating conditions.
| Engineering Dimension | ActionPower TITAN Grid Simulator | Chroma ATE 61815 Grid Simulator |
|---|---|---|
| System Architecture | Integrated regenerative grid emulator, typically deployed as cabinet or tower-class system | Modular regenerative AC power system with scalable parallel configuration |
| Power Scaling Philosophy | High-power capability achieved within a single coordinated architecture | Power expansion via parallelization of multiple internal or external modules |
| Bidirectional Operation | Native four-quadrant operation designed for continuous source and sink interaction | Four-quadrant operation with emphasis on stable regenerative absorption |
| Dynamic Grid Interaction | Optimized for aggressive EUT interaction, including rapid mode transitions and fault events | Optimized for controlled and repeatable grid condition playback |
| Transient Performance at High Power | Maintains dynamic integrity (slew rate, current response) at hundreds of kW to MW levels | Dynamic performance depends on module coordination at higher power levels |
| Grid Impedance Behavior | Actively controlled grid impedance suitable for stress testing and PHIL scenarios | Grid behavior primarily defined by programmed voltage profiles |
| Harmonic & Interharmonic Injection | Supports harmonic/interharmonic superposition with strict RMS voltage regulation | Supports standard-compliant harmonic and interharmonic injection |
| Unbalanced & Asymmetrical Conditions | Designed to sustain unbalanced operation under dynamic load feedback | Typically applied under predefined unbalance test sequences |
| Energy Regeneration Handling | Continuous regeneration to utility grid under fluctuating EUT feedback | Regenerative operation optimized for compliance test cycles |
| Primary EUT Types | PV inverters, ESS PCS, EV chargers, V2G systems, grid-forming converters | PV inverters, PCS, AC power conversion equipment under certification tests |
| Typical Application Environment | R&D labs, system integration testing, PHIL and stress validation | Certification labs, production validation, standards-focused testing |
| User Interaction Model | EUT- and scenario-driven test setup with emphasis on dynamic behavior | Procedure-driven testing aligned with standardized test scripts |
| Best Fit Use Cases | High-power, high-dynamics, bidirectional grid stress and interaction testing | Standardized grid compliance and repeatable certification workflows |
Selection Guide Based on EUT and Test Objectives
Although both ActionPower TITAN and Chroma 61815 provide regenerative grid simulation, their optimal use cases differ when evaluated from an EUT behavior and testing objective perspective rather than nominal specifications.
High-Dynamics, Bidirectional EUTs
For grid-interactive equipment with frequent source–sink transitions—such as PV inverters, ESS PCS, V2G chargers, and grid-forming converters—the grid simulator must behave as an active grid participant. In these scenarios, an integrated grid emulator architecture like ActionPower TITAN typically offers more consistent dynamic performance, especially at higher power levels.
Standards-Driven Compliance Testing
When the primary goal is repeatable execution of standardized grid disturbance tests (IEC 61000 series, IEEE 1547.1), the grid simulator functions mainly as a reference grid source.
Modular regenerative systems such as Chroma 61815 are well aligned with certification-oriented workflows, where procedural consistency and automation are prioritized.
High-Power Scaling Considerations
As testing power scales toward hundreds of kilowatts or beyond, architectural choices become increasingly relevant. Integrated systems tend to preserve transient integrity under dynamic conditions, while modular systems offer configuration flexibility with performance tied to parallel coordination.
Key Takeaways
The distinction between TITAN and 61815 is fundamentally architectural rather than parametric.
- TITAN favors dynamic interaction, high-power integrity, and R&D-oriented system validation
- 61815 emphasizes modularity, repeatability, and standards-focused compliance testing
Selecting the appropriate grid simulator should therefore be driven by EUT behavior, test dynamics, and long-term validation strategy, not headline ratings alone.
