How the NewFeed Relay Strengthens Solar, Grid and Backup Power Systems in South Africa

South Africa’s electrical landscape is undergoing rapid evolution. Solar PV installations, grid feeders, and backup generation systems are increasingly operating together in hybrid configurations.

This shift brings new protection challenges: reverse power flow from solar, voltage/frequency swings during load-shedding, high harmonic content from inverters and variable-speed drives (VSDs), and coordination issues between grid, BESS and diesel generation.

The NewElec NewFeed Relay is engineered for precisely this environment, offering advanced feeder and motor protection, power-quality diagnostics, and smart communication. In this article, we explore how NewFeed adds measurable value in solar farms, grid distribution and backup power systems and how it upgrades legacy protection schemes.

Why modern systems need smarter protection

Distribution networks in South Africa now face multiple simultaneous trends:

• High penetration of embedded generation (solar, often behind the meter).
• Long feeders and “weak” network zones where radial protection coordination is complex.
• Mixtures of inverter-based resources, diesel generators, battery energy storage (BESS) and conventional grid supply.
• Sensitive industrial loads and motors exposed to disturbances.

Traditional feeder relays were designed for one-way radial power flow from the substation to the load, with relatively simple fault profiles. But in this new environment, several new fault and disturbance modes arise:

• Reverse power flow into the network due to embedded generation.
• Voltage and frequency variations triggered by switching, load shedding or inverter behaviour.
• Harmonic distortion and imbalance caused by inverters, drives and non-linear loads.
• Hybrid source changeover where feeder protection must work seamlessly across grid, generator and battery systems.

For example, a GE document on feeder protection remarks that microprocessor-based relays “improve the operation of the distribution system through flexibility, programmability, and communications” in the face of unusual fault events.

In the embedded generation context, a technical standard for municipal interconnection in South Africa states that “reverse power protection” is required for generators and embedded systems. Thus, a modern relay like NewFeed becomes essential, not a luxury.

1. Solar PV and embedded generation: key protection issues

Reverse power flow and islanding risk

Solar and embedded generation can push power back upstream into the grid or into adjacent feeders. This changes the direction of flow and can upset protection coordination. A research paper on reverse-power flow protection in PV systems explains that “excess power may feed back into the substation and transmission grid … which may cause over-voltage on the feeder side, increase of the current magnitude during faults and … incorrect operation of the protective equipment.” 

The City of Cape Town’s SSEG handbook defines “reverse power flow blocking” as a necessity for embedded generation. The NewFeed Relay helps by detecting and acting on reverse power direction, allowing safe export limits and protecting both the plant and utility transformer.

Voltage and frequency instability

Inverter-based solar systems can change output quickly (for instance, when cloud cover passes). These rapid fluctuations can affect feeder voltage and system frequency, especially at high PV penetration. A summary of the anti-islanding function for solar systems notes that protection monitors voltage, frequency and reverse power flow, and trips when any exceed the defined limits. 

By including under-/over-voltage (ANSI 27/59) and under-/over-frequency (ANSI 81) protection functions as well as voltage unbalance (ANSI 46), the NewFeed Relay is designed to cope with the dynamic behaviour of solar-fed systems.

Harmonics and power quality impact

With large numbers of inverters, drives and nonlinear loads present, harmonics become a serious issue. According to A. Eberle’s explanation of harmonics: “Harmonics arise due to non-linear loads. They lead to distortion of the sine wave of voltage and current and affect the efficiency and service life of electrical devices and systems.” 

Another research paper found that harmonic distortion in distribution systems “can increase power losses by up to 20%.” The NewFeed Relay monitors harmonics (e.g., THD, individual orders) and gives engineers insight into whether the feeder is within acceptable PQ limits, enabling proactive maintenance and avoiding equipment damage.

Hybrid solar + generator + grid configurations

In many South African sites, solar PV is combined with diesel generators and grid backup. Protection must therefore coordinate across multiple sources. The NewFeed Relay’s integrated protection suite and motor/feeder diagnostics assist in these hybrid applications, enabling more reliable transitions between supply sources and reducing trip-outs during changeover.

2. Grid feeder protection in distribution networks

Distribution feeders are now more challenged than ever. Whether in municipalities, mining sites or industrial campuses, feeders may have:

• Mixed loads (motors, drives, lighting, IT).
• Embedded generation and export potential.
• Long radial runs with changing load profiles.
• Ageing infrastructure with less margin for error.

A key reference on feeder protection notes that feeders must be protected reliably during “unusual fault events such as high impedance ground faults and adjacent feeder faults” and that microprocessor-based relays offer flexibility in such situations.

Here are ways the NewFeed Relay creates value in feeder protection:

Full ANSI-based coverage

The relay supports a wide range of protection functions: overcurrent (50/51), earth-fault (50N/51N/64), thermal overload (49), undervoltage/overvoltage (27/59), under/over-frequency (81), phase failure/unbalance (46), reverse power, directional power, and more. This gives a single platform engineers can rely on, replacing multiple single-function relays and simplifying coordination.

Sequence component monitoring

Negative-sequence currents indicate imbalance and motor heating risk. Zero-sequence currents point to earth-fault or grounding issues. Being able to monitor and act on these components enables better protection of motors and feeders under modern operating conditions (drives, solar, generation). Research into motor and feeder protection stresses harmonic attenuation and bandwidth to limit nonlinearities, a feature that modern relays support.

Power quality visibility

Beyond fault clearing, modern feeder relays increasingly serve as monitoring devices for PQM. Harmonics, voltage trends, swells/dips, unbalance and frequency excursions can all be recorded and reported. Armed with this data, engineers can reduce nuisance trips, extend equipment lifespan and improve operational uptime.

Smart distribution network readiness

Communications protocols, remote settings groups, event logging and SCADA integration are no longer optional. The relay must integrate with network management systems. The GE feeder-protection reference emphasises how dynamic setting groups and communication tools improve performance.

3. Backup power systems: generators, BESS and UPS

Backup power systems are now multi-layered. Diesel generators still dominate many South African facilities, but battery systems, solar backing and UPS are increasingly part of the mix. Protection must therefore handle:

• Rapid changes in load when switching between sources.
• Nonlinear behaviour from battery inverters and UPS systems.
• Voltage/frequency instability during source transfer.
• Harmonic injection from BESS or UPS into feeders.

Here is how the NewFeed Relay supports these systems:

BESS and UPS integration

Battery and UPS systems often generate atypical waveforms and harmonic content. If the protection relay cannot differentiate between normal inverter behaviour and a true fault, nuisance tripping may occur. By providing harmonic monitoring and discerning control logic, the NewFeed Relay reduces false trips and ensures critical loads remain protected.

Changeover coordination and source transitions

Switching between grid, generator, and battery involves risk of voltage dips, frequency perturbations, unbalance or inrush currents. The relay’s advanced logic allows engineers to set dynamic behaviour during transitions, coordinate with breaker logic, supervise voltage/frequency recovery and respond appropriately. This gives more predictable behaviour during source transitions.

4. Comparing NewFeed with Legacy Systems

Across many South African operations, legacy relays such as the 320 Series Relay, GA/GA+ or GM0 are still in use. These units are reliable in their domain but limited in their functionality:

• Designed for one-way radial distribution without embedded generation.
• Basic fault detection (overcurrent, earth-fault) without harmonics or sequence monitoring.
• Limited or no communications capability.
• No built-in PQ measurement or inverter-type behaviour support.

By contrast, the NewFeed Relay delivers modern capabilities:

• Harmonics and PQ measurement (THD, harmonic orders) are crucial when inverters, drives and BESS are present.
• Reverse power and embedded generation export supervision are mandatory for modern solar networks.
• Full sequence component analysis and advanced logic settings.
• Embedded communications for remote monitoring and integration into SCADA.
• Starter integration and feeder control for motor-heavy sites.

For readers planning an upgrade, the Product Comparison Page (NewFeed vs KG Relay and KH Relay vs GA/GA+/GM0) provides a detailed feature-to-feature breakdown.

5. Industry-Specific Use Cases for South Africa

Solar Farms and Commercial PV Installations

In a ground-mount or rooftop PV installation, the NewFeed Relay helps engineers manage export limits, detect reverse power flow, monitor PQ issues at the inverter point of connection, and provide precise digital event records for troubleshooting.

Industrial Manufacturing Facilities

Large process plants with motors, drives, backup generation and embedded solar benefit from NewFeed’s comprehensive feeder protection across both LV and MV networks. The relay’s ability to monitor harmonics and unbalance extends motor life and reduces unplanned trips.

Water Treatment and Pumping Stations

Pump stations are often in remote or rural areas with long feeders, prime pumping motors, and backup generators. The NewFeed Relay protects against feeder unbalance, voltage dips, harmonics from drives, and supports generator-fed operation during outages, reducing downtime and avoiding pumping interruptions.

Mines and Processing Plants

Mining operations demand high reliability under challenging conditions. The NewFeed Relay supports hybrid power systems (solar + generator + grid), tracks and mitigates harmonics from crushers and drives, and allows early detection of feeder imbalance or PQ stress that would otherwise cause motor failures or conveyor stoppages.