Multi-Zone Protection (MZP)
Enabling robust protection of distributed networks
The unique ability of Refase to access many measurements over a wide geographical area, or traversing multiple feeder sections within a substation, enables convenient centralised protection and control functions. With multi-zone protection – incorporating up to 16 protected sections per fibre – combined with intelligent and highly-selective auto-reclose (AR or DAR). Means that we can provide very granular unit protection of lines, cables, and other assets – including at very remote locations where it would be challenging and costly to install conventional monitoring equipment.
Each Refase system can issue time-critical trip and control commands, typically using GOOSE communications, and can interface with existing SCADA systems. Sample Value data streams can be provided to existing substation equipment where necessary.
Our unique multi-zone protection capability can be applied to feeders, hybrid circuits (composed of multiple underground cable and overhead line sections), busbars within substations, and individual sections of offshore wind farm export cables. This approach is also ideal for monitoring, protecting, and controlling distributed generation – particularly wind farms.
There are several technical, practical, and cost benefits arising from this integrated, centralised protection approach:
- Auto-reclose of healthy sections, with highly granular selectivity, reduces outages and customer minutes lost (CML)
- Minimised loss of income following faults – particularly for remote generators and offshore wind farms where maintenance is challenging
- Avoids double exposure to fault currents caused by manual fault location
- Highly cost-effective busbar protection
- Faster-acting multi-ended differential protection, due to elimination of the typical wide-area communications delay of 2-6 ms, and elimination of other complications such as asymmetrical delay
- Enables rapid and discrete post-event response – all measurements are accurately time synchronised which facilitates examining fault records for complex events
- Readily supports new grid connections with minimal civil engineering works
- Multiple uses from same instrumentation infrastructure
Through our development partners field deployments with Scottish Power Energy Networks and Statnett, the platform is proven to support modern digital substation protocols, including IEC 61850-9-2 Sampled Values, IEC 61850-8-1 GOOSE, and IEC 61850-9-3 (IEEE 1588 PTPv2). The hardware also supports PRP and HSR redundancy protocols.