* The International Development Association, the World Bank's affiliate for concessionary lending, has approved a $22.1 million credit to Haiti to help expand power generation there.

Two 7.8 megawatt diesel generating units will be installed at the Carrefour power plant, which is being built near the capital city of Port-au-Prince with IDA funds. A four-year supply of spare parts also will be purchased.

Improvements also will be made at existing power plants. A new cooling tower will be built at the Varreux diesel electric power plant in Port-au-Prince, and auxiliary equipment for several other plants will be purchased. Spare parts needed to maintain three hydro-turbine generators at the Peligre hydroelectric plant, which provides more than half the electric power for Port-au-Prince, also will be bought.

The IDA credit is for 50 years, with a 10-year grace period.

* The IDA has approved a $15 million credit to Malawi to help finance an $18.2 million housing project which will benefit more than 3,000 families.

Two Malawi government agencies will oversee the project. The Malawi Housing Corp. will develop 2,230 plots, and the New Building Society will provide mortgage financing for 2,000 houses.

The Housing Corp. will build homes on two sites during the first year of the project. In subsequent years, it will reserve at least 30 percent of the plots for construction by individuals, or by contractors acting for groups of individuals.

The project will be reviewed annually to ensure that the program is benefiting the widest possible range of income groups.

An additional 500 plots will be developed in existing housing areas, and the Housing Corp. will provide loans for building materials to 1,000 low-income families.

In addition, technical assistance will be provided to help Malawi's housing sector continue growing. A training program will be set up to help small local contractors meet housing standards. A four-year land demarcation and land survey claims adjudication program also will be established.

The New Building Society will provide $1.3 million for the projects, the Malawi Housing Corp., $600,000, and the government of Malawi, $500,000. The remaining $800,000 will be raised from mortgage down payments. The New Building Society also will provide an additional $3.1 million for refinancing land development.

The IDA credit is for a term of 50 years, including 10 grace years. The credit carries no interest, but is subject to annual charges of 0.5 percent on undisbursed balances and 0.75 percent on disbursed balances.