INTEGRATION OF RENEWABLE ENERGY SYSTEMS & CURTAILMENT OF GENERATION

Developed Power Systems need re-design. Opportunities for less developed power systems.

A blurb of my research work.

In response to a trilemma of climate change, security of energy supply and rising costs, most nations have set ambitious targets of decarbonizing, among other initiatives, their electricity supply system by increasing the penetration of renewable generation technologies, such as Wind and Solar, in their portfolio of energy systems connected to their hitherto passive and uni-directional power systems. This will always lead to failure of existing systems except a fundamental rethink in the design, operation and management of power systems is effected.

For example, increasing penetration of renewable generation technologies connected to the UK distribution system led to the mal-operation of legacy directional overcurrent protection system as the network grapples with the reality of bi-directional flow of power. Similar outcomes have been reported worldwide with the curtailment of Roof Top Solar generation in Southern Australia in the last few months.

In reaction to the problem of mal-operation of directional overcurrent protection system in the UK, relay manufacturers and the electricity supply industry have embarked on the installation of load blinding relays which haven’t solved the problem. The transition from legacy systems to new ones require careful thinking and assessments in order not to jeopardize the integrity, reliability, and stability of the existing system.

My research describes a process of managing the transition in a coordinated manner proposing changes to existing protection settings philosophy, while effecting a new directional overcurrent protection and control scheme that separates the protection function from its reverse power flow requirements.

The maximum amount of distributed generation (DG) that can be absorbed by a piece of electrical network for network demand (L), distributed generation (G), demand power factor (cosα), and generation power factor (cosβ) without the mal-operation of the directional overcurrent (DOC) protection system was determined using the Idowu Oyebanjo factor “K”,
where K = (cosβ – sinα)/(sinα+cosβ).

The theoretical minimum limit of “K”, Lmin, was determined using a number of integro-differential equations for the minimum function R=√{L^2 +G^2-2LGcos(α+β)}.

Lmin = LminG,α,β +/- √ LminG,α,β^2+ S^2- G^2

R = Maximum Reverse Power Flow

S = Installed Protection Settings on the DOC Relay

∆ = Relay Characteristic Angle of DOC Relay

Applying the following boundary conditions:

1 -135°<∆<+45°

2. R < S

3. LminG,α,β – √{ LminG,α,β^2+ S^2- G^2} < Lmin < G(cosβ – sinα)/(sinα +cosβ)

4. √(G^2 – S^2) < LminG,α,β

My becoming a Professor of Power Systems in the future will be based on developing these equations as they will be needed in a decarbonized world of power systems.

Idowu Oyebanjo PhD